Review Article Reactor Neutrinosdownloads.hindawi.com/journals/ahep/2013/453816.pdfMiddle and long-baseline oscillation experiments at Daya Bay, Double Chooz, and RENO provided very

Hindawi Publishing CorporationAdvances in High Energy PhysicsVolume 2013 Article ID 453816 34 pageshttpdxdoiorg1011552013453816

Review ArticleReactor Neutrinos

Soo-Bong Kim1 Thierry Lasserre2 and Yifang Wang3

1 KNRC Department of Physics and Astronomy Seoul National University Seoul 151-742 Republic of Korea2 CEA Irfu SPP Centre de Saclay 91191 Gif-sur-Yvette France and Astroparticule et Cosmologie APC 10 rue Alice Domon et LeonieDuquet 75205 Paris Cedex 13 France

3 Institute of High Energy Physics Yu-Quan road 19B Beijing 100049 China

Correspondence should be addressed to Yifang Wang yfwangihepaccn

Received 18 August 2012 Accepted 20 December 2012

Academic Editor Koichiro Nishikawa

Copyright copy 2013 Soo-Bong Kim et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

We review the status and the results of reactor neutrino experiments Short-baseline experiments have provided the measurementof the reactor neutrino spectrum and their interest has been recently revived by the discovery of the reactor antineutrino anomalya discrepancy between the reactor neutrino flux state of the art prediction and the measurements at baselines shorter than onekilometer Middle and long-baseline oscillation experiments at Daya Bay Double Chooz and RENO provided very recently themost precise determination of the neutrino mixing angle 120579

13 This paper provides an overview of the upcoming experiments and

of the projects under development including the determination of the neutrino mass hierarchy and the possible use of neutrinosfor society for nonproliferation of nuclear materials and geophysics

1 Introduction 80 Years ofReactor Neutrino Physics

Invented by Pauli [1] in 1930 named by Amaldi in 1934 andlater modeled in the Fermi theory of beta decay [2] Theweakly coupling neutrino was first searched for by Reinesand Cowan Starting at the Hanford nuclear reactor (Wash-ington) they later moved to the new Savannah River Plant(South Carolina) to perform their definitive and ground-breaking experimental detectionThis breakthrough had twoimportant consequences resolving and clarifying the unsat-isfactory situation of a fundamental particle needed for theconsistency of theory but first thought to be unobservableand demonstrating the possibility of using neutrinos as asensitive probe of particle physics Indeed several years afterthe completion of the pioneering Reines and Cowanrsquos workneutrinos were beginning to be used regularly to investigatethe weak interactions the structure of nucleons and theproperties of their constituent quarks

In the first crude experiment of 1953 [3] Reines andCowanrsquos goal was to demonstrate unambiguously a reactioncaused in a target by a neutrino produced elsewhere Theexperiment pioneered the delayed coincidence technique tosearch for the reaction ]

119890+ 119901 rarr 119890

++ 119899 where an electron

antineutrino from the Hanford nuclear reactor interactedwith a free proton in a large tank filled with cadmium-loaded liquid scintillator The positron and the resultantannihilation gamma rays are detected as a prompt signalwhile the neutron is thermalized in the liquid scintillatorand subsequently captured by the cadmium The excitednucleus then emits gamma radiation which is detected as thedelayed signal The first result at two standard deviationswas followed in 1956 and 1958 by more precise experiments[4ndash6] where the significance improved to over four standarddeviations In addition to the detection the reaction cross-section was measured to be 11 plusmn 26 times 10

minus44 cm2 [6]Nowadays reactor neutrinos like Daya Bay KamLAND orDouble Chooz are still detected through similar experimentalmethods

2 Nuclear Reactors and Neutrinos

Nuclear reactors are very intense sources of neutrinos thathave been used all along the neutrinorsquos history from itsdiscovery up to the most recent oscillation studies With anaverage energy of about 200MeV released per fission and 6neutrinos produced along the 120573-decay chains of the fission

2 Advances in High Energy Physics

products one expects about 2times 1020 ]119904 emitted in a 4120587 solidangle from a 1GW reactor (thermal power) Since unstablefission products are neutron-rich nuclei all 120573 decays are of120573minus type and the neutrino flux is actually pure electronic

antineutrinos (]119890)

The neutrino oscillation search at a reactor is alwaysbased on a disappearance measurement using the powerfulinverse beta decay (IBD) detection process to discriminatethe neutrino signal from backgrounds The observed neu-trino spectrum at a distance 119871 from a reactor is comparedto the expected spectrum If a deficit is measured it canbe interpreted in terms of the disappearance probabilitywhich in the two neutrino mixing approximation reducesto

119875119890119890= 1 minus sin22120579 sin2 (Δ119898

2119871

4119864) (1)

where Δ1198982 is the difference between the squared masses ofthe two neutrino states and 120579 is the mixing angle fixing theamplitude of the oscillation

Here we will especially consider reactor antineutrinodetector at short distances below 100m from the reactor corein particular ILL-Grenoble Goesgen Rovno KrasnoyarskSavannah River and Bugey [7ndash15] These experiments haveplayed an important role in the establishment of neutrinophysics and especially neutrino oscillations over the lastfifty years Unlike modern long-baseline reactor experimentsmotivated by the measurement of the last unknown mixingangle 120579

13[16ndash18] which measure 119875

119890119890by comparing the event

rate and spectrum in two detectors at different distances theaforementioned short baseline experiments can only employone detector and therefore depend on an accurate theoreticalprediction for the emitted ]

119890flux and spectrum to measure

119875119890119890Until late 2010 all data from reactor neutrino experiments

appeared to be fully consistent with the mixing of ]119890 ]120583

and ]120591with three mass eigenstates ]

1 ]2 and ]

3 with

the squared mass differences |Δ119898231| ≃ 24 10

minus3eV2 andΔ1198982

21|Δ1198982

31| ≃ 0032 The measured rate of ]e was found

to be in reasonable agreement with that predicted from theldquooldrdquo reactor antineutrino spectra [19ndash21] though slightlylower than expected with the measuredexpected ratio at0980plusmn0024 including recent revisions of the neutronmeanlifetime 120591

119899= 8815 s in 2011 (PDG)

In preparation for the Double Chooz reactor experiment[16] the Saclay reactor neutrino group reevaluated the spe-cific reactor antineutrino flux for 235U 239Pu 241Pu and 238UIn 2011 they reported their results [22] which correspond to aflux that is a few percent higher than the previous predictionThis also necessitates a reanalysis of the ratio of the observedevent rate to the predicted rate for 19 published experimentsat reactor-detector distances below 100m

21 Reference Antineutrino Spectra Fission reactors releaseabout 1020 ]

119890GWminus1sminus1 which mainly come from the beta

decays of the fission products of 235U 238U 239Pu and241Pu The emitted antineutrino spectrum is then givenby

119878tot (119864]) = sum

119896

119891119896119878119896(119864]) (2)

where 119891119896refers to the contribution of the main fissile

nuclei to the total number of fissions of the kth branchand 119878

119896to their corresponding neutrino spectrum per

fissionThe distribution of the fission products of uranium

or plutonium isotopes covers hundreds of nuclei each ofthem contributing to 119878

119896(119864) through various 120573 decay chains

At the end the total antineutrino spectrum is a sum ofthousands of 120573-branches weighted by the branching ratio ofeach transition and the fission yield of the parent nucleusDespite the impressive amount of data available in nucleardatabases the ab initio calculation of the emitted antineutrinospectrum is difficult Moreover when looking at the detectedspectrum through the IBD process the 1806MeV thresholdand the quadratic energy dependence of the cross-sectionenhance the contribution of transitions with large endpoints(1198640gt 4MeV) Systematic errors of the nuclear data and the

contribution of poorly known nuclei become a real limitationfor the high energy part of the antineutrino spectrumUncertainties below the 10 level seem to be out of reachwiththe ab initio approach preventing any accurate oscillationanalysis

In order to circumvent this issue measurements of total120573 spectra of fissile isotopes were performed in the 1980s atILL [19ndash21] a high flux research reactor in Grenoble FranceThin target foils of fissile isotopes 235U 239Pu and 241Puwere exposed to the intense thermal neutron flux of thereactor A tiny part of the emitted electrons could exit the corethrough a straight vacuum pipe to be detected by the highresolution magnetic spectrometer BILL [23] The electronrates were recorded by a pointwise measurement of thespectrum in magnetic field steps of 50 keV providing anexcellent determination of the shape of the electron spectrumwith subpercent statistical error The published data weresmoothed over 250 keV Except for the highest energy binswith poor statistics the dominant error was the absolutenormalization quoted around 3 (90 CL) with weakenergy dependence

In principle the conversion of a 120573-spectrum into anantineutrino spectrum can be done using the energy conser-vation between the two leptons

119864119890+ 119864] = 1198640 (3)

with 1198640 the endpoint of the 120573 transition However this

approach requires to know the contribution of all singlebranches in the ILL sectra and this information is notaccessible from the integral measurement Therefore a spe-cific conversion procedure was developped using a set of30 ldquovirtualrdquo 120573-branches fitted on the data The theoretical

Advances in High Energy Physics 3

expression for the electron spectrum of a virtual branch wasof the form119878virtual (119885 119860 119864119890) = 119870⏟⏟⏟⏟⏟⏟⏟

NormtimesF(119885 119860 119864

119890)⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Fermi function

times 119901119890119864119890(119864119890minus 1198640)2

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Phasespace

times (1 + 120575 (119885 119860 119864119890))⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Correction

(4)

where 119885 and 119860 are the charge and atomic number of theparent nucleus and 119864

0is the endpoint of the transition

The origin of each term is described by the underbracesThe 120575 term contains the corrections to the Fermi theory Inthe ILL papers it included the QED radiative correctionsas calculated in [24] The 119885 dependence comes from theCoulomb corrections Since a virtual branch is not connectedto any real nucleus the choice of the nuclear charge wasdescribed by the observed mean dependence of 119885 on 119864

0in

the nuclear databases

119885 (1198640) = 495 minus 07119864

0minus 009119864

2

0 119885 le 34 (5)

The 119860 dependence is weaker and linked to the determi-nation of 119885 through global nuclear fits

Once the sum of the 30 virtual branches is fitted to theelectron data each of them is converted to an antineutrinobranch by substituting 119864

119890by 1198640minus 119864] in (4) and applying

the correct radiative corrections The predicted antineutrinospectrum is the sum of all converted branches At the end ofthis procedure an extra correction term is implemented in aneffective way as

Δ119878branch (119864]) ≃ 065 (119864] minus 400) (6)

This term is an approximation of the global effect of weakmagnetism correction and finite size Coulomb correction[25]

The final error of the conversion procedure was estimatedto be 3-4 (90 CL) to be added in quadrature with theelectron calibration error which directly propagates to theantineutrino prediction From these reference spectra theexpected antineutrino spectrum detected at a reactor can becomputed All experiments performed at reactors since thenrelied on these reference spectra to compute their predictedantineutrino spectrum

22 New Reference Antineutrino Spectra Triggered by theneed for an accurate prediction of the reactor antineutrinoflux for the first phase of the Double Chooz experimentwith a far detector only the determination of antineutrinoreference spectra has been revisited lately [22] In a firstattempt a compilation of the most recent nuclear datawas performed for an up-to-date ab initio calculation ofthe antineutrino fission spectra The asset of this approachis the knowledge of each individual 120573 branch providinga perfect control of the conversion between electron andantineutrino spectra As a powerful cross-check the sumof all the branches must match the very accurate electronspectra measured at ILL Despite the tremendous amountof nuclear data available this approach failed to meet therequired accuracy of few for two main reasons as follows

(i) The majority of the 120573 decays are measured using 120573-120574 coincidences which are sensitive to the so-calledpandemonium effect [26] The net result is an exper-imental bias of the shape of the energy spectra withthe high energy part being overestimated relative tothe low energy part New measurements are ongoingwith dedicated experimental setups to correct for thepandemonium effect but in the case of the referencespectra many unstable nuclei have to be studied

(ii) As mentioned above an important fraction of thedetected neutrinos has a large energy (gt4MeV)The associated 120573 transitions mostly come from veryunstable nuclei with a large energy gap between theparent ground state and the nuclear levels of thedaughter nucleus Their decay scheme is often poorlyknown or even not measured at all

A reference data set was constituted based on all fissionproducts indexed in the ENSDF database [27] All nucleimeasured separtely to correct for the pandemonium effectwere substitutedwhen not in agreementwith the ENSDFdata(67 nuclei from [28] and 29 nuclei from [29]) A dedicatedinterface BESTIOLE reads the relevant information of thisset of almost 10000 120573-branches and computes their energyspectrum based on (4) Then the total beta spectrum of onefissioning isotope is built as the sum of all fission fragmentspectra is weighted by their activityThese activities are deter-mined using a simulation package called MCNP Utility forReactor Evolution (MURE [30]) Following this procedurethe predicted fission spectrum is about 90 of the referenceILL 120573 spectra as illustrated in Figure 2 for the 235U isotopeThe missing contribution is the image of all unmeasureddecays as well as the remaining experimental biases of themeasurements To fill the gap one can invoke models of thedecay scheme of missing fission products Reaching a goodagreement with the ILL electron data remains difficult withthis approach

Another way to fill the gap is to fit the missing contri-bution in the electron spectrum with few virtual branchesThe same ILL procedure can be used except that the virtualbranches now rest on the base of physical transitions Thismixed approach combines the assets of ab initio and virtualbranches methods as follows

(i) The prediction still matches accurately the referenceelectron data from the ILL measurements

(ii) 90 of the spectrum is built with measured 120573 transi-tions with ldquotruerdquo distributions of endpoint branchingratios nuclear charges and so forth This suppressesthe impact of the approximations associated with theuse of virtual beta branches

(iii) All corrections to the Fermi theory are applied at thebranch level preserving the correspondence betweenthe reference electron data and the predicted antineu-trino spectrum

The new predicted antineutrino spectra are found about3 above the ILL spectra This effect is comparable forthe 3 isotopes (235U 239Pu and 241Pu) with little energy


119864 (MeV)1 2 3 4 5 6 7 8

minus006

minus004

minus002

0

002

004

006

119885 = 46

119885(119864) used in ILL paper119885(119864) from ENSDF

(119873tr

ue120584

minus119873

fit 120584)119873

true

120584

(a)

1 2 3 4 5 6 7 8minus006

minus004

minus002

0

002

004

006

120584 kinetic energy (MeV)

(119873tr

ue120584

minus119873

conv

120584)119873

true

120584(b)

Figure 1 Numerical tests of the conversion-induced deviations from a ldquotruerdquo spectrum built from a set of known branches (see text fordetails) (a) Effect of various 119885(119864) polynomials used in the formula of the virtual branches (b) Deviation of converted spectra with theeffective correction of (6) (solid line) or with the correction applied at the branch level

0 2 4 6 8 10203040506070

1198640 (MeV)

Figure 2 The effective nuclear charge 119885 of the fission fragments of235U as a function of 119864

0 The area of the each box is proportional

to the contribution of that particular 119885 to the fission yield in thatenergy bin The lines are fits of quadratic polynomials Black color-ENSDF database other colors illustrate the small sensitivity todifferent treatment of the missing isotopes

dependence The origin and the amplitude of this bias couldbe numerically studied in detail following a method initiallydevelopped in [31] A ldquotruerdquo electron spectrum is definedas the sum of all measured branches Since all the branchesare known the ldquotruerdquo antineutrino spectrum is perfectlydefined as well with no uncertainty from the conversionApplying the exact same conversion procedure than in theeighties on this new electron reference confirms the 3 shiftbetween the converted antineutrino spectrum and the ldquotruerdquospectrum

Further tests have shown that this global 3 shift isactually a combination of two effects At high energy (119864 gt

4MeV) the proper distribution of nuclear charges providedby the dominant contribution of the physical 120573-branches

induces a 3 increase of the predicted antineutrino spectrumOn the low energy side it was shown that the effective linearcorrection of (6) was not accounting for the cancellationsoperating between the numerous physical branches when thecorrection is applied at the branch level (see Figure 1)

Beyond the correction of these above biases the uncer-tainty of the new fission antineutrino spectra couldnrsquot bereduced with respect to the initial predictions The nor-malisation of the ILL electron data a dominant source oferror is inherent to any conversion procedure using theelectron reference Then a drawback of the extensive use ofmeasured 120573-branches in the mixed approach is that it bringsimportant constraints on the missing contribution to reachthe electron data In particular the inducedmissing shape canbe difficult to fit with virtual branches preventing a perfectmatch with the electron reference These electron residualsare unfortunately amplified as spurious oscillations in thepredicted antineutrino spectrum leading to comparable con-version uncertainties (see red curve in Figure 3) Finally thecorrection of the weak magnetism effect is calculated in aquite crude way and the same approximations are used sincethe eighties

In the light of the above results the initial conversionprocedure of the ILL data was revisited [32] It was shownthat a fit using only virtual branches with a judicious choiceof the effective nuclear charge could provide results withminimum bias A mean fit similar to (5) is still used butthe nuclear charge of all known branches is now weighted byits contribution in the total spectrum that is the associatedfission yield As shown in Figure 2 the result is quite stableunder various assumptions for theweighting of poorly known


2 3 4 5 6 7 8

0

005

01

015

119864120584 (MeV)

minus005

(120601minus120601

ILL)120601

ILL

Our result11012663

ILL inversionSimple 120573 shape

Figure 3 Comparison of different conversions of the ILL electrondata for 235U Black curve cross-check of results from [19] followingthe same procedure Red curve results from [22] Green curveresults from [32] using the same description of 120573 decay as in [22]Blue curve update of the results from [22] including correctionsto the Fermi theory as explained in the text The thin error barsshow the theory errors from the effective nuclear charge119885 and weakmagnetism The thick error bars are the statistical errors

nuclei The bias illustrated in the left plot of Figure 1 iscorrected

The second bias (Figure 1(b)) is again corrected byimplementing the corrections to the Fermi theory at thebranch level rather than using effective corrections as in(6) Using the same expression of these corrections than in[22] the two independent new predictions are in very goodagreement (Figure 3) confirming the 3 global shift Notethat the spurious oscillations of the Mueller et al spectra areflattened out by this new conversion because of the betterzeroing of electron residuals

A detailed review of all corrections to the Fermi theory isprovided in [32] including finite size corrections screeningcorrection radiative corrections and weak magnetism Toa good approximation they all appear as linear correctionterms as illustrated in Figure 4 in the case of a 10MeVendpoint energyThis refined study of all corrections leads toan extra increase of the predicted antineutrino spectra at highenergy as illustrated by the blue curve in Figure 3 The neteffect is between 10 and 14 more detected antineutrinosdepending on the isotope (see Table 1)

The corrections of Figure 4 are knownwith a good relativeaccuracy except for the weak magnetism term At the presenttime a universal slope factor of about 05 per MeV isassumed neglecting any dependence on nuclear structure[25] Accurate calculation for every fission product is out ofreach Using the conserved vector current hypothesis it ispossible to infer the weak magnetism correction from theelectromagnetic decay of isobaric analog states Examples ofthe slope factors computed from the available data are shownin Table I of [32] While most examples are in reasonableagreement with the above universal slope some nuclei withlarge value of log119891119905 have a very large slope factorMoreover areview of the nuclear databases [33] shows that 120573 transitionswith log119891119905 gt 7 contribute between 15 and 30 to the totalspectrum Still the data on the weak magnetism slopes arescarce and none of them corresponds to fission products At

0 2 4 6 8 10

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

119864120584 (MeV)

1198710

1198710

119866120584

0 2 4 6 8 10

119866120573

119864119890 (MeV)

S

S C

C

120575WM

120575WM

Figure 4 Shown is the relative size of the various corrections tothe Fermi theory for a hypothetical 120573 decay with 119885 = 46 119860 =

117 and 1198640= 10MeV The upper panel shows the effect on the

antineutrino spectrum whereas the lower panel shows the effect onthe 120573 spectrum 120575WM weak magnetism correction 119871

0 C Coulomb

and weak interaction finite size corrections S screening correction119866]120573 radiative corrections

Table 1 Relative change of the new predicted events rates withrespect to the ILL reference (in)The relative change of the emittedflux is always close to 3 dominated by the few first bins because theenergy spectra are dropping fast

(119877new minus 119877ILL)119877ILL235U 239Pu 241Pu 238U

Values from [22] 25 31 37 98Values from [32] 37 42 47 mdash

this stage it is difficult to conclude if the uncertainty of theweak magnetism correction should be inflated or not Theprescription of the ILL analysis 100 corresponds to about1 of the detected neutrino rate The best constraints couldactually come from shape analysis of the reactor neutrino datathemselves The Bugey and Rovno data are accurate altoughdetailed information on the detector response might bemissing for such a detailed shape analysis The combinationof the upcoming Daya Bay Double Chooz and RENO datashould soon set stringent limits on the global slope factor

The error budget of the predicted spectra remains againcomparable to the first ILL analysis The normalizationerror of the electron data is a common contribution Theuncertainties of the conversion by virtual branches have beenextensively studied and quantified based on the numericalapproach The uncertainty induced by the weak magnetismcorrections is faute de mieux evaluated with the same100 relative error The final central values and errors aresummarized in table [22]

23 Off-Equilibrium Effects For an accurate analysis of reac-tor antineutrino data an extra correction to the referencefission spectra has to be applied It is often of the order of


the percent It comes from the fact that the ILL spectra wereacquired after a relatively short irradiation time between 12hours and 18 days depending on the isotopes whereas in areactor experiment the typical time scale is several months Anonnegligible fraction of the fission products have a lifetimeof several days Therefore the antineutrinos associated withtheir 120573 decay keep accumulating well after the ldquophotographat 1 dayrdquo of the spectra taken at ILL Very long-lived isotopescorrespond to nuclei close to the bottom of the nuclear valleyof stability Hence one naively expects these 120573 transitionsto contribute at low energy For a quantitative estimate ofthis effect the same simulations developed in [22] for theab initio calculation of antineutrino spectra were used Thesensitivity to the nuclear ingredients is suppressed becauseonly the relative changes between the ILL spectra and spectraof longer irradiations at commercial reactors were computedThe corrections to be applied are summarized in [22] Asexpected they concern the low energy part of the detectedspectrum and vanish beyond 35MeV The corrections arelarger for the 235U spectrum because its irradiation time 12 his shorter than the othersTheuncertaintywas estimated fromthe comparison between the results of MURE and FISPACcodes as well as from the sensitivity to the simulated coregeometry A safe 30 relative error is recommended

24 238U Reference Spectrum The 238U isotope is contribut-ing to about 8 of the total number of fissions in a stan-dard commercial reactor These fissions are induced by fastneutrons therefore their associated 120573-spectrum could notbe measured in the purely thermal flux of ILL A dedicatedmeasurement in the fast neutron flux of the FRMII reactor inMunich has been completed and should be published in thecoming months [34]

Meanwhile the ab initio calculation developed in [22]provides a useful prediction since the relatively small con-tribution of 238U can accommodate larger uncertainties inthe predicted antineutrino spectrum An optimal set of 120573-brancheswas tuned tomatch the ILL spectra of fissile isotopesas well as possible The base of this data set consists of theENSDF branches corrected for the pandemonium effect asdescribed in Section 22 Missing 120573 emitters are taken fromthe JENDL nuclear database [35] where they are calculatedusing the gross-theory [36] Finally the few remaining nucleiwere described using amodel based onfits of the distributionsof the endpoints and branching ratios in the ENSDFdatabasethen extrapolated to the exotic nuclei

The comparison with the reference 235U ILL data showathat the predicted spectrum agrees with the reference at theplusmn10 level

Then this optimal data set is used to predict a 238Uspectrum Again the activity of each fission product is cal-culated with the evolution code MURE The case of an N4commercial reactor operating for one year was simulatedAfter such a long irradiation time the antineutrino spectrumhas reached the equilibrium The results are summarizedin [22] The central values are about 10 higher than theprevious prediction proposed in [37]This discrepancymightbe due to the larger amount of nuclei taken into account in the

most recent work Nevertheless both results are comparablewithin the uncertainty of the prediction roughly estimatedfrom the deviation with respect to the ILL data and thesensitivity to the chosen data set

25 Summary of the New Reactor Antineutrino Flux Predic-tion In summary a reevaluation of the reference antineu-trino spectra associated to the fission of 235U 239Pu and241Pu isotopes [22] has revealed some systematic biases in thepreviously published conversion of the ILL electron data [19ndash21] The net result is a ≃ +3 shift in the predicted emittedspectra The origin of these biases was not in the principleof the conversion method but in the approximate treatmentof nuclear data and corrections to the Fermi theory Acomplementary work [32] confirmed the origin of the biasesand showed that an extra correction term should be addedincreasing further the predicted antineutrino spectra at highenergy These most recent spectra are the new reference usedfor the analysis of the reactor anomaly in the next sectionTheprediction of the last isotope contributing to the neutrino fluxof reactors 238U is also updated by ab initio calculations

The new predicted spectra and their errors are presentedin [22] The deviations with respect to the old referencespectra are given in Table 1

3 Investigating Neutrino Oscillations

31 Exploring the Solar Oscillation The sun is a well-definedneutrino source to provide important opportunities of inves-tigating nontrivial neutrino properties because of the widerange of matter density and the great distance from the sun tothe earth Precise measurement of solar neutrinos is a directtest of the standard solar model (SSM) that is developed fromthe stellar structure and evolution

Solar neutrinos have been observed by several experi-ments Homestake with a chlorine detector SAGE GALLEXand GNO with gallium detectors Kamiokande and Super-Kamiokande with water Cherenkov detectors and SNOwith a heavy water detector Most recently Borexino hassuccessfully observed low energy solar neutrinos with theirenergy spectrum using a liquid scintillator detector of ultralow radioactivity

The first observation of solar neutrinos by the Homestakeexperiment demonstrated the significantly smaller measuredflux than the SSM prediction known as ldquothe solar neutrinopuzzlerdquo at that time SAGE GALLEX and GNO are sen-sitive to the most abundant 119901119901 solar neutrinos and alsoobserved the deficit Kamiokande-II and Super-Kamiokandesucceeded in real-time and directional measurement ofsolar neutrinos in a water Cherenkov detector The solarneutrino problem was solved by SNO through the flavor-dependent measurement using heavy water In 2001 theinitial SNO charged current result combined with the Super-Kamiokandersquos high-statistics ]119890 elastic scattering result pro-vided direct evidence for flavor conversion of solar neutri-nos The later SNO neutral current measurements furtherstrengthened the conclusionThese results are consistent withthose expected from the largemixing angle (LMA) solution of


solar neutrino oscillation inmatter withΔ1198982sol sim 5times10minus5 eV2

and tan2120579sol sim 045The KamLAND reactor neutrino experiment at a flux-

weighted average distance of sim180 km obtained a result ofreactor antineutrino disappearance consistent with the LMAsolar neutrino solution The current solar neutrino andKamLAND data suggest that Δ1198982

21= (750plusmn020)times10

minus5 eV2

with a fractional error of 27 and sin2212057912= 0857 plusmn 0024

with a fractional error of 28

32 Exploring the Atmospheric Oscillation The Super-Kam-iokande obtained the first convincing evidence for theneutrino oscillation in the observation of the atmosphericneutrinos in 1998 A clear deficit of atmospheric muonneutrino candidate events was observed in the zenith-angle distribution compared to the no-oscillation expecta-tion The distance-to-energy 119871119864 distribution of the Super-Kamiokande data demonstrated ]

120583harr ]120591oscillations and

completely ruled out some of exotic explanations of theatmospheric neutrino disappearance such as neutrino decayand quantum decoherence

Accelerator experiments can better measure the valueof |Δ1198982atm| than the atmospheric neutrino observation dueto a fixed baseline distance and a well-understood neutrinospectrum K2K is the first long-baseline experiment to study]120583oscillations in the atmosphericΔ1198982 regionwith a neutrino

path length exceeding hundreds of kilometers MINOS isthe second long-baseline experiment for the atmosphericneutrino oscillation using a ]

120583beam The MINOS finds the

atmospheric oscillation parameters as |Δ1198982atm| = (232+012

minus008)times

10minus3eV2 and sin22120579atm gt 090 at 90 CL OPERA using

the CNGS ]120583beam reported observation of one ]

120591candidate

T2K began a new long-baseline experiment in 2010 andis expected to measure |Δ119898

2

atm| and sin2120579atm even morepricisely No]a is expected to be in operation soon for theaccurate measurement of atmospheric neutrino oscillationparameters

The current atmospheric neutrino and accelerator datasuggest thatΔ1198982

32(31)= (232

+012

minus008)times10minus3 eV2 with a fractional

error of 43 and sin2212057923

= 097 plusmn 003 with a fractionalerror of 31

33 Measuring the Last and Smallest Neutrino Mixing Angle12057913 In the presently accepted paradigm to describe the

neutrino oscillations there are three mixing angles (12057912 12057923

and 12057913) and one phase angle (120575) in the Pontecorvo-Maki-

Nakagawa-Sakata matrix [38ndash40] It was until 2012 that 12057913is

the most poorly known and smallest mixing angleMeasurements of 120579

13are possible using reactor neutrinos

and accelerator neutrino beams Reactor measurements havethe property of determining 120579

13without the ambiguities

associated matter effects and CP violation In addition thedetector for a reactor measurement is not necessarily largeand the construction of a neutrino beam is not needed Thepast reactor measurement had a single detector which wasplaced about 1 km from the reactors The new generationreactor experiments Daya Bay Double Chooz and RENOusing two detectors of 10 sim 40 tons at near (300 sim 400m)

200 m

EH3

EH1

EH2

AD6 AD4

AD3

AD1 AD2

AD5

L1L2

L3L4

D1D2

Daya Bay NPP

Ling Ao-II NPP

Ling Ao NPP

Figure 5 Layout of the Daya Bay experiment The dots representreactors labeled as D1 D2 L1 L2 L3 and L4 Six ADs AD1ndashAD6are installed in three EHs

and far (1 sim 2 km) locations have significantly improvedsensitivity for 120579

13down to the sin2(2120579

13) sim 001 level With

12057913determined and measurements of ]

120583rarr ]e and ]

120583rarr ]e

oscillations using accelerator neutrino beams impinging onlarge detectors at long baselines will improve the knowledgeof 12057913and also allow access to matter or CP violation effects

Previous attempts at measuring 12057913

via neutrino oscilla-tions have obtained only upper limits [41ndash43] the CHOOZ[41 42] and MINOS [44] experiments set the most stringentlimits sin22120579

13lt 015 (90 CL) In 2011 indications

of a nonzero 12057913

value were reported by two acceleratorappearance experiments T2K [45] and MINOS [46] andby the Double Chooz reactor disappearance experiment [4748] Global analyses of all available neutrino oscillation datahave indicated central values of sin22120579

13that are between

005 and 01 (see eg [49 50]) In 2012 Daya Bay andRENO reported definitive measurements of the neutrinooscillation mixing angle 120579

13 based on the disappearance

of electron antineutrinos emitted from reactors The 12057913

measurements by the three reactor experiments are presentedin the following sections

4 Daya Bay

TheDaya Bay collaboration announced onMarch 8 2012 thediscovery of a nonzero value for the last unknown neutrinomixing angle 120579

13[51] based on 55 days of data taking It

is consistent with previous and subsequent measurements[45ndash48 52] An improved analysis using 139 days of data isreported at international conferences and a paper is nowunder preparation [53]

41 The Experiment The Daya Bay nuclear power complexis located on the Southern coast of China 55 km to thenortheast ofHongKong and 45 km to the East of Shenzhen Adetailed description of theDaya Bay experiment can be foundin [54] As shown in Figure 5 the nuclear complex consists ofsix pressurized water reactors grouped into three pairs witheach pair referred to as a nuclear power plant (NPP) All six


Table 2 Vertical overburden muon rate 119877120583 and average muon energy 119864

120583of the three EHs and baselines from antineutrino detectors AD1-6

to reactors D1 D2 and L1-4 in meters

Halls Overburden (mwe) 119877120583(Hzm2) 119864

120583(GeV) ADs D1 D2 L1 L2 L3 L4

EH1 250 127 57 AD1 362 372 903 817 1354 1265EH1 250 127 57 AD2 358 368 903 817 1354 1266EH2 265 095 58 AD3 1332 1358 468 490 558 499EH3 860 0056 137 AD4 1920 1894 1533 1534 1551 1525EH3 860 0056 137 AD5 1918 1892 1535 1535 1555 1528EH3 860 0056 137 AD6 1925 1900 1539 1539 1556 1530

RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO

Figure 6 Schematic diagram of the Daya Bay detectors

cores are functionally identical pressurized water reactors of29GW thermal power [55] Three underground experimen-tal halls (EHs) are connected with horizontal tunnels Twoantineutrino detectors (ADs) are located in EH1 two (onlyone installed at this moment) in EH2 and four (only threeinstalled) ADs are positioned near the oscillation maximumin EH3 (the far hall) The baselines from six ADs to six coresare listed in Table 2 They are measured by several differenttechniques and cross-checked by independent groups asdescribed in [53]The overburdens the simulated muon rateand average muon energy are also listed in Table 2

The ]es are detected via the inverse 120573 decay (IBD)reaction ]

119890+ 119901 rarr 119890

++ 119899 in a gadolinium-doped

liquid scintillator (Gd-LS) [56ndash58] Each AD has three nestedcylindrical volumes separated by concentric acrylic vessels asshown in Figure 6 The innermost volume holds 20 t of 01by weight Gd-LS that serves as the antineutrino target Themiddle volume is called the gamma catcher and is filled with21 t of undoped liquid scintillator (LS) for detecting gammarays that escape the target volumeThe outer volume contains37 t of mineral oil (MO) to provide optical homogeneityand to shield the inner volumes from radiation originatingfor example from the photomultiplier tubes (PMTs) or thestainless steel containment vessel (SSV) There are 192 8-inch PMTs (Hamamatsu R5912) mounted on eight laddersinstalled along the circumference of the SSV and withinthe mineral oil volume To improve uniformity the PMTs

are recessed in a 3mm thick black acrylic cylindrical shieldlocated at the equator of the PMT bulb

Three automated calibration units (ACU-A ACU-B andACU-C) are mounted at the top of each SSV Each ACU isequipped with a LED a 68Ge source and a combined sourceof 241Am-13C and 60CoTheAm-C source generates neutronsat a rate of 05HzThe rates of the 60Co and 68Ge sources areabout 100 Hz and 15 Hz respectively

The muon detection system consists of a resistive platechamber (RPC) tracker and a high-purity active water shieldThe water shield consists of two optically separated regionsknown as the inner (IWS) and outer (OWS) water shieldsEach region operates as an independent water Cherenkovdetector In addition to detecting muons that can producespallation neutrons or other cosmogenic backgrounds in theADs the pool moderates neutrons and attenuates gammarays produced in the rock or other structural materials in andaround the experimental hall At least 25mofwater surroundthe ADs in every direction Each pool is outfitted with a lighttight cover with dry nitrogen flowing underneath

Each water pool is covered with an overlapping arrayof RPC modules [59] each with a size of 2m times 2m Thereare four layers of bare RPCs inside each module The stripshave a ldquozigzagrdquo design with an effective width of 25 cm andare stacked in alternating orientations providing a spatialresolution of sim8 cm

Each detector unit (AD IWS OWS and RPC) is readout with a separate VME crate All PMT readout cratesare physically identical differing only in the number ofinstrumented readout channels The front-end electronicsboard (FEE) receives raw signals from up to sixteen PMTssums the charge among all input channels identifies over-threshold channels records timing information on over-threshold channels and measures the charge of each over-threshold pulse The FEE in turn sends the number ofchannels over threshold and the integrated charge to thetrigger system When a trigger is issued the FEE reads outthe charge and timing information for each over-thresholdchannel as well as the average ADC value over a 100 ns time-window immediately preceding the over-threshold condition(pre-ADC)

Triggers are primarily created internally within eachPMT readout crate based on the number of over-thresholdchannels (Nhit) as well as the summed charge (E-Sum) fromeach FEE The system is also capable of accepting externaltrigger requests for example from the calibration system


FID of delayed candidates

Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5

minus2 minus15 minus1 minus05 0 05 1 15 2

Figure 7 Discrimination of flasher events and IBD-delayed signalsin the neutron energy region The delayed signals of IBDs have thesame distribution for all six Ads while the flashers are different

42 Data Monte Carlo Simulation and Event ReconstructionThe data used in this analysis were collected from December24 2011 through May 11 2012

The detector halls operated independently linked onlyby a common clock and GPS timing system As such datafrom each hall were recorded separately and linked offlineSimultaneous operation of all three detector halls is requiredto minimize systematic effects associated with potentialreactor power excursions

Triggers were formed based either on the number ofPMTs with signals above a sim025 photoelectron (pe) thresh-old (Nhit triggers) or the charge sum of the over-thresholdPMTs (E-Sum trigger)

A small number of AD PMTs called flashers sponta-neously emit light presumably due to a discharge withinthe base The visible energy of such events covers a widerange from sub-MeV to 100MeV Two features were typicallyobserved when a PMT flashed The observed charge for agiven PMT was very high with light seen by the surroundingPMTs and PMTs on the opposite side of the AD saw lightfrom the flasher

To reject flasher events a flasher identification variable(FID) was constructed Figure 7 shows the discriminationof flasher events for the delayed signal of IBD candidatesThe inefficiency for selection was estimated to be 002 Theuncorrelated uncertainties among ADs were estimated to be001The contamination of the IBD selection was evaluatedto be lt 10minus4

The AD energy response has a time dependence adetector spatial dependence (nonuniformity) and a particlespecies and energy dependence (nonlinearity) The goal ofenergy reconstruction was to correct these dependences inorder tominimize theAD energy scale uncertaintyThe LEDswere utilized for PMT gain calibration while the energy scalewas determined with a 60Co source deployed at the detectorcenterThe sources were deployed once per week to check forand correct any time dependence

AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd

Reconstructed energy (MeV)

1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572

Figure 8 Asymmetry values for all six ADsThe sources 68Ge 60Coand Am-C were deployed at the detector center The alphas frompolonium decay and neutron capture on gadolinium from IBD andspallation neutronswere uniformly distributedwithin each detectorDifferences between these sources are due to spatial nonuniformityof detector response

A scan along the z-axis utilizing the 60Co source fromeach of the three ACUs was used to obtain nonuniformitycorrection functions The nonuniformity was also studiedwith spallation neutrons generated by cosmic muons andalphas produced by natural radioactivity present in the liquidscintillator The neutron energy scale was set by comparing60Co events with neutron capture on Gd events from theAm-C source at the detector center Additional details ofenergy calibration and reconstruction can be found in [54]Asymmetries in the mean of the six ADsrsquo response are shownin Figure 8 Asymmetries for all types of events in all the ADsfall within a narrow band and the uncertainty is estimated tobe 05 uncorrelated among ADs

A Geant4 [60] based computer simulation (Monte CarloMC) of the detectors and readout electronics was used tostudy detector response and consisted of five componentskinematic generator detector simulation electronics simula-tion trigger simulation and readout simulation The MC iscarefully tuned by takingmeasured parameters of themateri-als properties to match observed detector distributions suchas PMT timing charge response and energy nonlinearityAn optical model is developed to take into account photonabsorption and reemission processes in liquid scintillator

43 Event Selection Efficiencies and Uncertainties Two pres-elections were completed prior to IBD selection First flasher


Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12

Figure 9 The prompt energy spectrum from AD1 IBD selectionrequired 07 lt 119864

119901lt 120MeV Accidental backgrounds were

subtracted where the spectrum of accidental background wasestimated from the spectrum of all gt07MeV triggers

events were rejected Second triggers within a (minus2120583s 200120583s)window with respect to a water shield muon candidate (120583WS)were rejected where a 120583WS was defined as any trigger withNhitgt12 in either the inner or outerwater shieldThis allowedfor the removal of most of the false triggers that followeda muon as well as triggers associated with the decay ofspallation products Events in an AD within plusmn2120583s of a 120583WSwith energy gt20MeV or gt25GeV were classified as ADmuons (120583AD) or showering muons (120583sh) respectively

Within an AD only prompt-delayed pairs separated intime by less than 200120583s (1 lt 119905

119889minus 119905119901lt 200 120583s where 119905

119901

and 119905119889are time of the prompt and delayed signal resp) with

no intervening triggers and no 119864 gt 07MeV triggers within200120583s before the prompt signal or 200 120583s after the delayedsignal were selected (referred to as the multiplicity cut) Aprompt-delayed pair was vetoed if the delayed signal is incoincidence with a water shield muon (minus2 120583s lt 119905

119889minus 119905120583W119878

lt

600 120583s) or an AD muon (0 lt 119905119889minus 119905120583AD

lt 1000 120583s) or ashowering muon (0 lt 119905

119889minus 119905120583sh

lt 1 s) The energy of thedelayed candidate must be 60MeV lt 119864

119889lt 120MeV

while the energy of the prompt candidate must be 07MeV lt

119864119901lt 120 MeV The prompt energy the delayed energy and

the capture time distributions for data and MC are shown inFigures 9 10 and 11 respectively

The data are generally in good agreement with the MCThe apparent difference between data and MC in the promptenergy spectrum is due to nonlinearity of the detectorresponse however the correction to this nonlinearity wasnot performed in this analysis Since all ADs had similarnonlinearity (as shown in the bottom pannel of Figure 8)and the energy selection cuts cover a larger range than theactual distribution the discrepancies introduced negligibleuncertainties to the rate analysis

For a relative measurement the absolute efficienciesand correlated uncertainties do not factor into the error

Delayed energy (MeV)

0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV

Figure 10 The delayed energy spectrum from AD1 IBD selectionrequired 60 lt 119864


subtracted where the spectrum of accidental background wasestimated from the spectrum of single neutrons

1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s

Figure 11 The neutron capture time from AD1 IBD selectionrequired 1 lt 119905

119889minus 119905119901lt 200 120583s In order to compare data with MC a

cut on prompt energy (119864119901gt 3MeV) was applied to reject accidental

backgrounds

budget In that regard only the uncorrelated uncertaintiesmatter Extracting absolute efficiencies and correlated errorswere done in part to better understand our detector andit was a natural consequence of evaluating the uncorrelateduncertainties Efficiencies associated with the prompt energydelayed energy capture time Gd capture fraction and spill-in effects were evaluated with the Monte Carlo Efficienciesassociated with the muon veto multiplicity cut and livetimewere evaluated using data In general the uncorrelated uncer-tainties were not dependent on the details of our computersimulation

Table 3 is a summary of the absolute efficiencies and thesystematic uncertainties The uncertainties of the absolute


Table 3 Summary of absolute efficiencies and systematic uncertain-ties For our relative measurement only the uncorrelated uncertain-ties contribute to the final error in our relative measurement

Efficiency Correlated UncorrelatedTarget protons 047 003Flasher cut 9998 001 001Delayed energy cut 909 06 012Prompt energy cut 9988 010 001Multiplicity cut 002 lt001Capture time cut 986 012 001Gd capture ratio 838 08 lt01Spill-in 1050 15 002Livetime 1000 0002 lt001

efficiencies were correlated among the ADs No relativeefficiency except 120598

120583120598119898 was corrected All differences between

the functionally identical ADs were taken as uncorrelateduncertainties Detailed description of the analysis can befound in [53]

44 Backgrounds Backgrounds are actually the main sourceof systematic uncertainties of this experiment even thoughthe background to signal ratio is only a few percent Extensivestudies show that cosmic-ray-induced backgrounds are themain component while AmCneutron sources installed at thetop of our neutrino detector for calibration contribute alsoto a significant portion Although the random coincidencebackground is the largest its uncertainty is well undercontrol Table 4 lists all the signal and background rates aswell as their uncertainties A detailed study can be found in[53]

The accidental background was defined as any pair ofotherwise uncorrelated triggers that happen to satisfy theIBD selection criteria They can be easily calculated basedon textbooks and their uncertainties are well understoodWhen calculating the rate of accidental backgrounds listedin Table 4 A correction is needed to account for the muonveto efficiency and themultiplicity cut efficiency An alternatemethod called the off-windows method was developedto determine accidental backgrounds This result was alsovalidated by comparing the prompt-delayed distance ofaccidental coincidences selected by the off-windows methodwith IBD candidates The relative differences between off-windows method results and theoretical calculation of 6ADswere less than 1

Energetic neutrons entering an AD aped IBD by recoilingoff a proton before being captured on GdThe number of fastneutron background events in the IBD sample is estimated byextrapolating the prompt energy (119864

119901) distribution between 12

and 100MeV down to 07MeV Two different extrapolationmethods were used one is a flat distribution and the otherone is a first-order polynomial function The fast neutronbackground in the IBD sample was assigned to be equalto the mean value of the two extrapolation methods andthe systematic error was determined from the sum of theirdifferences and the fitting uncertainties As a check the fast

neutrons prompt energy spectrum associated with taggedmuons validates our extrapolation method

The rate of correlated background from the 120573-n cascadeof 9Li 8He decays was evaluated from the distribution ofthe time since the last muon and can be described by asum of exponential functions with different time constant[61] To reduce the number of minimum ionizing muons inthese data samples we assumed that most of the 9Li and8He production was accompanied with neutron generationThe muon samples with and without reduction were bothprepared for 9Li and 8He background estimation By con-sidering binning effects and differences between results withand without muon reduction we assigned a 50 systematicalerror to the final result

The 13C (120572119899)16O background was determined by mea-suring alpha decay rates in situ and then by using MC tocalculate the neutron yield We identified four sources ofalpha decays the 238U 232Th 227Ac decay chains and 210Potaking into account half lives of their decay chain products1643 120583s 03 120583s and 1781 ms respectively Geant4 was usedto model the energy deposition process Based on JENDL[62] (120572n) cross-sections the neutron yield as a function ofenergy was calculated and summed Finally with the in-situmeasured alpha decay rates and the MC determined neutronyields the 13C(120572119899)16O rate was calculated

During data taking the Am-C sources sat inside theACUs on top of each AD Neutrons emitted from thesesources would occasionally ape IBD events by scatteringinelastically with nuclei in the shielding material (emittinggamma rays) before being captured on a metal nuclei suchas Fe Cr Mn or Ni (releasing more gamma rays) Weestimated the neutron-like events from the Am-C sourcesby subtracting the number of neutron-like singles in the119885 lt 0 region from the 119885 gt 0 region The Am-C correlatedbackground ratewas estimated byMC simulation normalizedusing the Am-C neutron-like event rate obtained from dataEven though the agreement between data andMC is excellentfor Am-C neutron-like events we assigned 100 uncertaintyto the estimated background due to the Am-C sources toaccount for any potential uncertainty in the neutron capturecross-sections used by the simulation

45 Side-By-Side Comparison in EH1 Relative uncertaintieswere studied with data by comparing side-by-side antineu-trino detectors A detailed comparison using three monthsof data from ADs in EH1 has been presented elsewhere[54] An updated comparison of the prompt energy spectraof IBD events for the ADs in EH1 using 231 days of data(Sep 23 2011 to May 11 2012) is shown in Figure 12 aftercorrecting for efficiencies and subtracting backgroundAbin-by-bin ratio of the AD1 and AD2 spectra is also shown Theratio of total IBD rates in AD1 and AD2 was measured tobe 0987 plusmn 0004 (stat) plusmn 0003 (syst) consistent with theexpected ratio of 0982 The difference in rates was primarilydue to differences in baselines of the two ADs in addition toa slight dependence on the individual reactor onoff status Itwas known that AD2 has a 03 lower energy response thanAD1 for uniformly distributed events resulting in a slight tilt


Table 4 Signal and background summary The background and IBD rates were corrected for the 120598120583120598119898efficiency

AD1 AD2 AD3 AD4 AD5 AD6IBD candidates 69121 69714 66473 9788 9669 9452Expected IBDs 68613 69595 66402 99229 99402 98377DAQ livetime (days) 1275470 1273763 1262646Muon veto time (days) 225656 229901 181426 23619 23638 24040120598120583120598119898

08015 07986 08364 09555 09552 09547Accidentals (per day) 973 plusmn 010 961 plusmn 010 755 plusmn 008 305 plusmn 004 304 plusmn 004 293 plusmn 003

Fast neutron (per day) 077 plusmn 024 077 plusmn 024 058 plusmn 033 005 plusmn 002 005 plusmn 002 005 plusmn 002

9Li8He (per AD per day) 29 plusmn 15 20 plusmn 11 022 plusmn 012

Am-C correlated (per AD per day) 02 plusmn 02

13C(120572 119899) 16O background (per day) 008 plusmn 004 007 plusmn 004 005 plusmn 003 004 plusmn 002 004 plusmn 002 004 plusmn 002

IBD rate (per day) 66247 plusmn 300 67087 plusmn 301 61353 plusmn 269 7757 plusmn 085 7662 plusmn 085 7497 plusmn 084

0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12

AD1AD2Shifted AD1AD2

Prompt energy (MeV)0 5 10

(b)

Figure 12 The energy spectra for the prompt signal of IBD eventsin AD1 and AD2 (a) are shown along with the bin-by-bin ratio (b)Within (b) the dashed line represents the ratio of the total ratesfor the two ADs and the open circles show the ratio with the AD2energy scaled by +03

to the distribution shown in Figure 12(b) The distribution ofopen circles was created by scaling the AD2 energy by 03The distribution with scaled AD2 energy agrees well with aflat distribution

46 Reactor Neutrino Flux Reactor antineutrinos result pri-marily from the beta decay of the fission products of fourmain isotopes 235U 239Pu 238U and 241Pu The ]e flux ofeach reactor (119878(119864)) was predicted from the simulated fissionfraction 119891

119894and the neutrino spectra per fission (119878

119894) [19ndash

22 32 37] of each isotope [63]

119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)

where 119894 and 119896 sum over the four isotopes 119864119894is the energy

released per fission and119882th is the measured thermal powerThe thermal power data were provided by the power

plant The uncertainties were dominated by the flow ratemeasurements of feedwater through three parallel coolingloops in each core [63ndash65] The correlations between theflow meters were not clearly known We conservativelyassume that they were correlated for a given core but wereuncorrelated between cores giving amaximal uncertainty forthe experiment The assigned uncorrelated uncertainty forthermal power was 05

A simulation of the reactor cores using commercialsoftware (SCIENCE [66 67]) provided the fission fraction asa function of burnupThe fission fraction carries a 5 uncer-tainty set by the validation of the simulation software The3D spatial distribution of the isotopes within a core was alsoprovided by the power plant although simulation indicatedthat it had a negligible effect on acceptance A complementarycore simulation package was developed based on DRAGON[68] as a cross-check and for systematic studies The codewas validated with the Takahama-3 benchmark [69] andagreed with the fission fraction provided by the power plantto 3 Correlations among the four isotopes were studiedusing the DRAGON-based simulation package and agreedwell with the data collected in [70] Given the constraintsof the thermal power and correlations the uncertaintiesof the fission fraction simulation translated into a 06uncorrelated uncertainty in the neutrino flux

The neutrino spectrum per fission is a correlated uncer-tainty that cancels out for a relative measurement Thereaction cross-section for isotope 119894 was defined as 120590

119894=

int 119878119894(119864])120590(119864])119889119864] where 119878119894(119864]) is the neutrino spectra per

Advances in High Energy Physics 13IB

D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3

Dec 27 Jan 26 Feb 25 Mar 26 Apr 25

Run timeDec 27 Jan 26 Feb 25 Mar 26 Apr 25


Predicted (sin2212057913 = 0)Predicted (sin2212057913 = 089)

Figure 13 The daily average measured IBD rates per AD in thethree experimental halls are shown as a function of time along withpredictions based on reactor flux analyses and detector simulation

fission and 120590(119864120583) is the IBD cross-section We took the

reaction cross-section from [10] but substituted the IBDcross-section with that in [71]The energy released per fissionand its uncertainties were taken from [72] Nonequilibriumcorrections for long-lived isotopes were applied following[22] Contributions from spent fuel [73 74] (sim03) wereincluded as an uncertainty

The uncertainties in the baseline and the spatial distribu-tion of the fission fractions in the core had a negligible effectto the results

Figure 13 presents the background-subtracted and effi-ciency-corrected IBD rates in the three experimental hallsPredicted IBD rate from reactor flux calculation and detectorMonte Carlo simulation are shown for comparison Thedashed lines have been corrected with the best-fit normal-ization parameter 120576 in (10) to get rid of the biases from theabsolute reactor flux uncertainty and the absolute detectorefficiency uncertainty

47 Results The ]119890rate in the far hall was predicted with

a weighted combination of the two near hall measurementsassuming no oscillation A ratio of measured-to-expectedrate is defined as

119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)

Table 5 Reactor-related uncertainties

Correlated UncorrelatedEnergyfission 02 Power 05IBD reactionfission 3 Fission fraction 06

Spent fuel 03Combined 3 Combined 08

where 119873119891and 119872

119891are the predicted and measured rates

in the far hall (sum of AD 4ndash6) and 119872119886and 119872

119887are the

measured IBD rates in EH1 (sum of AD 1-2) and EH2 (AD3)respectively The values for 120572 and 120573 were dominated by thebaselines and only slightly dependent on the integrated fluxof each core For the analyzed data set 120572 = 00439 and120573 = 02961 The residual reactor-related uncertainty in 119877 was5 of the uncorrelated uncertainty of a single coreThe deficitobserved at the far hall was as follows

R = 0944 plusmn 0007 (stat) plusmn 0003 (syst) (9)

The value of sin2212057913

was determined with a 1205942 con-

structed with pull terms accounting for the correlation of thesystematic errors [75] as follows

1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)

where 119872119889is the measured IBD events of the 119889th AD

with backgrounds subtracted 119861119889is the corresponding back-

ground 119879119889is the prediction from neutrino flux MC and

neutrino oscillations and 120596119889

119903is the fraction of IBD con-

tribution of the 119903th reactor to the 119889th AD determinedby baselines and reactor fluxes The uncorrelated reactoruncertainty is 120590

119903(08) as shown in Table 5 120590

119889(02) is the

uncorrelated detection uncertainty listed in Table 8 120590119861is the

background uncertainty listed in Table 4 The correspondingpull parameters are (120572

119903 120576119889 and 120578

119889)Thedetector- and reactor-

related correlated uncertainties were not included in theanalysis the absolute normalization 120576 was determined fromthe fit to the data

The survival probability used in the 1205942 was

119875sur = 1 minus sin2212057913sin2 (1267Δ1198982

31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231

= 232 times 10minus3eV2 sin22120579

12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020

minus021times 10minus5eV2 The uncertainty in Δ119898

2

31had

negligible effect and thus was not included in the fitThe best-fit value is

sin2212057913= 0089 plusmn 0010 (stat) plusmn 0005 (syst) (12)


Weighted baseline (km)

09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913

Figure 14 Ratio of measured versus expected signal in eachdetector assuming no oscillation The error bar is the uncorrelateduncertainty of each ADThe expected signal was corrected with thebest-fit normalization parameter The oscillation survival probabil-ity at the best-fit value is given by the smooth curve The AD4 andAD6 data points were displaced by minus30 and +30m for visual clarityThe 1205942 versus sin22120579

13is shown in the inset

with a 1205942NDF of 344 All best estimates of pull param-eters are within its one standard deviation based on thecorresponding systematic uncertainties The no-oscillationhypothesis is excluded at 77 standard deviations Figure 14shows the measured number of events in each detectorrelative to those expected assuming no oscillation A sim15oscillation effect appears in the near halls The oscillationsurvival probability at the best-fit values is given by thesmooth curve The 1205942 versus sin22120579


The observed ]119890spectrum in the far hall was compared to

a prediction based on the near hall measurements120572119872119886+120573119872119887

in Figure 15 The distortion of the spectra is consistent withthe expected one calculated with the best-fit 120579

13obtained

from the rate-only analysis providing further evidence ofneutrino oscillation

5 Double Chooz

The Double Chooz detector system (Figure 16) consists ofa main detector an outer veto and calibration devices Themain detector comprises four concentric cylindrical tanksfilled with liquid scintillators or mineral oil The innermost8mm thick transparent (UV to visible) acrylic vessel housesthe 10m3 ]-target liquid a mixture of n-dodecane PXEPPO bis-MSB and 1 g gadoliniuml as a beta-diketonatecomplex The scintillator choice emphasizes radiopurity andlong-term stability The ]-target volume is surrounded by the120574-catcher a 55 cm thick Gd-free liquid scintillator layer ina second 12mm thick acrylic vessel used to detect 120574-raysescaping from the ]-targetThe light yield of the 120574-catcherwaschosen to provide identical photoelectron (pe) yield acrossthese two layers Outside the 120574-catcher is the buffer a 105 cm

0

500

1000

1500

2000

Far hallNear halls (weighted)

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12

No oscillationBest fit


(b)

Figure 15 (a) Measured prompt energy spectrum of the far hall(sum of three ADs) compared with the no-oscillation predictionfrom the measurements of the two near halls Spectra were back-ground subtracted Uncertainties are statistical only (b)The ratio ofmeasured and predicted no-oscillation spectra The red curve is thebest-fit solution with sin22120579

13= 0089 obtained from the rate-only

analysis The dashed line is the no-oscillation prediction

thick mineral oil layer The buffer works as a shield to 120574-rays from radioactivity of PMTs and from the surroundingrock and is one of the major improvements over the CHOOZdetector It shields from radioactivity of photomultipliers(PMTs) and of the surrounding rock and it is one of themajor improvements over the CHOOZ experiment 390 10-inch PMTs are installed on the stainless steel buffer tankinner wall to collect light from the inner volumesThese threevolumes and the PMTs constitute the inner detector (ID)Outside the ID and optically separated from it is a 50 cmthick inner veto liquid scintillator (IV) It is equipped with78 8-inch PMTs and functions as a cosmic muon veto and asa shield to spallation neutrons produced outside the detectorThe detector is surrounded by 15 cm of demagnetized steelto suppress external 120574-rays The main detector is covered byan outer veto system The readout is triggered by customenergy sum electronics The ID PMTs are separated into twogroups of 195 PMTs uniformly distributed throughout thevolume and the PMT signals in each group are summed


Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV

Stainless steel vessel holding 390 PMTs

Acrylic vessels

120584-target (NT)

7 m

7 m

Figure 16 A cross-sectional view of the Double Chooz detectorsystem

The signals of the IV PMTs are also summed If any of thethree sums is above a set energy threshold the detector is readout with 500MHz flash-ADC electronics with customizedfirmware and a dead time-free acquisition system Uponeach trigger a 256 ns interval of the waveforms of both IDand IV signals is recorded Having reduced the ambientradioactivity enables us to set a low trigger rate (120Hz)allowed the ID readout threshold to be set at 350 keV wellbelow the 102MeV minimum energy of an IBD positrongreatly reducing the threshold systematics The experimentis calibrated by several methods A multiwavelength LED-fiber light injection system (LI) produces fast light pulsesilluminating the PMTs from fixed positions Radio-isotopes137Cs 68Ge 60Co and 252Cf were deployed in the targetalong the vertical symmetry axis and in the gamma catcherthrough a rigid loop traversing the interior and passing alongboundaries with the target and the buffer The detector wasmonitored using spallation neutron captures on H and Gdresidual natural radioactivity and daily LI runs The energyresponse was found to be stable within 1 over time

51 Chooz Reactor Modeling Double Choozrsquos sources ofantineutrinos are the reactor cores B1 and B2 at the Electricitede France (EDF) Centrale Nucleaire de Chooz two N4 typepressurized water reactor (PWR) cores with nominal thermalpower outputs of 425GWth eachThe instantaneous thermalpower of each reactor core 119875

119877

th is provided by EDF as afraction of the total power It is derived from the in-coreinstrumentation with the most important variable being thetemperature of the water in the primary loop The dominantuncertainty on the weekly heat balance at the secondaryloops comes from the measurement of the water flow At thenominal full power of 4250MW the final uncertainty is 05(1 120590 CL) Since the amount of data taken with one or twocores at intermediate power is small this uncertainty is usedfor the mean power of both cores

The antineutrino spectrum for each fission isotope istaken from [22 32] including corrections for off-equilibriumeffects The uncertainty on these spectra is energy dependentbut is on the order of 3 The fractional fission rates 120572

119896

of each isotope are needed in order to calculate the meancross-section per fission They are also required for thecalculation of themean energy released per fission for reactor119877

⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)

The thermal power one would calculate given a fission isrelatively insensitive to the specific fuel composition since the⟨119864119891⟩119896differ by lt6 however the difference in the detected

number of antineutrinos is amplified by the dependence ofthe norm andmean energy of 119878

119896(119864) on the fissioning isotope

For this reasonmuch effort has been expended in developingsimulations of the reactor cores to accurately model theevolution of the 120572

119896

Double Chooz has chosen two complementary codesfor modeling of the reactor cores MURE and DRAGON[30 76ndash78] These two codes provide the needed flexibilityto extract fission rates and their uncertainties These codeswere benchmarked against data from the Takahama-3 reactor[79] The construction of the reactor model requires detailedinformation on the geometry and materials comprising thecore The Chooz cores are comprised of 205 fuel assem-blies For every reactor fuel cycle approximately one yearin duration one-third of the assemblies are replaced withassemblies containing fresh fuel The other two-thirds ofthe assemblies are redistributed to obtain a homogeneousneutron flux across the coreThe Chooz reactor cores containfour assembly types that differ mainly in their initial 235Uenrichment These enrichments are 18 34 and 4 Thedata set reported here spans fuel cycle 12 for core B2 andcycle 12 and the beginning of cycle 13 for B1 EDF providesDouble Chooz with the locations and initial burnup of eachassembly Based on these maps a full core simulation wasconstructed usingMURE for each cycleThe uncertainty dueto the simulation technique is evaluated by comparing theDRAGON and MURE results for the reference simulationleading to a small 02 systematic uncertainty in the fissionrate fractions 120572

119896 Once the initial fuel composition of the

assemblies is known MURE is used to model the evolutionof the full core in time steps of 6 to 48 hours This allowsthe 120572119896rsquos and therefore the predicted antineutrino flux to

be calculated The systematic uncertainties on the 120572119896rsquos are

determined by varying the inputs and observing their effecton the fission rate relative to the nominal simulation Theuncertainties considered are those due to the thermal powerboron concentration moderator temperature and densityinitial burnup error control rod positions choice of nucleardatabases choice of the energies released per fission andstatistical error of the MURE Monte Carlo The two largestuncertainties come from the moderator density and controlrod positions

In far-only phase of Double Chooz the rather largeuncertainties in the reference spectra limit the sensitivity to


Table 6 The uncertainties in the antineutrino prediction Alluncertainties are assumed to be correlated between the two reactorcores They are assumed to be normalization and energy (rate andshape) unless noted as normalization only

Source Normalization only Uncertainty ()119875th Yes 05⟨120590119891⟩Bugey Yes 14

119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18

12057913 To mitigate this effect the normalization of the cross-

section per fission for each reactor is anchored to the Bugey-4rate measurement at 15m [10]

⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)

where119877 stands for each reactorThe second term corrects thedifference in fuel composition between Bugey-4 and each ofthe Chooz cores This treatment takes advantage of the highaccuracy of the Bugey-4 anchor point (14) and suppressesthe dependence on the predicted ⟨120590

119891⟩119877 At the same time the

analysis becomes insensitive to possible oscillations at shorterbaselines due to heavy Δ1198982 sim 1 eV2 sterile neutrinos Theexpected number of antineutrinos with no oscillation in the119894th energy bin with the Bugey-4 anchor point becomes asfollows

119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)

where 120598 is the detection efficiency 119873119901is the number of

protons in the target 119871119877is the distance to the center of

each reactor and 119875119877

th is the thermal power The variable⟨119864119891⟩119877is the mean energy released per fission defined in (13)

while ⟨120590119891⟩119877is the mean cross-section per fission defined

in (14) The three variables 119875119877th ⟨119864119891⟩119877 and ⟨120590119891⟩119877are time

dependent with ⟨119864119891⟩119877and ⟨120590

119891⟩119877depending on the evolution

of the fuel composition in the reactor and 119875119877th depending onthe operation of the reactor A covariance matrix 119872exp

119894119895=

120575119873exp119894120575119873

exp119895

is constructed using the uncertainties listed inTable 6

The IBD cross-section used is the simplified form fromVogel and Beacom [71]The cross-section is inversely propor-tional to the neutron lifetimeTheMAMBO-II measurementof the neutron lifetime [80] is being used leading to 119870 =

0961 times 10minus43 cm2MeV minus2

52 Modeling the Double Chooz Detector The detectorresponse uses a detailed Geant4 [81 82] simulation withenhancements to the scintillation process photocathode

optical surface model and thermal neutron model Simu-lated IBD events are generated with run-by-run correspon-dence of MC to data with fluxes and rates calculated asdescribed in the previous paragraph Radioactive decays incalibration sources and spallation products were simulatedusing detailed models of nuclear levels taking into accountbranching ratios and correct spectra for transitions [83ndash85]Optical parameters used in the detector model are based ondetailed measurements made by the collaboration Tuning ofthe absolute and relative light yield in the simulationwas donewith calibration data The scintillator emission spectrumwas measured using a Cary Eclipse Fluorometer [86] Thephoton emission time probabilities used in the simulationare obtained with a dedicated laboratory setup [87] Forthe ionization quenching treatment in our MC the lightoutput of the scintillators after excitation by electrons [88]and alpha particles [89] of different energies was measuredThe nonlinearity in light production in the simulation hasbeen adjusted to match these dataThe finetuning of the totalattenuation was made using measurements of the completescintillators [87] Other measured optical properties includereflectivities of various detector surfaces and indices ofrefraction of detector materials

The readout system simulation (RoSS) accounts for theresponse of elements associated with detector readout suchas from the PMTs FEE FADCs trigger system andDAQThesimulation relies on the measured probability distributionfunction (PDF) to empirically characterize the response toeach single PE as measured by the full readout channel TheGeant4-based simulation calculates the time at which eachPE strikes the photocathode of each PMT RoSS convertsthis time per PE into an equivalent waveform as digitizedby FADCs After calibration the MC and data energies agreewithin 1

A set of Monte Carlo ]119890events representing the expected

signal for the duration of physics data taking is created basedon the formalism of (16) The calculated IBD rate is used todetermine the rate of interactions Parent fuel nuclide andneutrino energies are sampled from the calculated neutrinoproduction ratios and corresponding spectra yielding aproperly normalized set of IBD-progenitor neutrinos Oncegenerated each event-progenitor neutrino is assigned a ran-dom creation point within the originating reactor core Theevent is assigned a weighted random interaction point withinthe detector based on proton density maps of the detectormaterials In the center-of-mass frame of the ]minus119901 interactiona random positron direction is chosen with the positronand neutron of the IBD event given appropriate momentabased on the neutrino energy and decay kinematics Thesekinematic values are then boosted into the laboratory frameThe resulting positron and neutronmomenta and originatingvertex are then available as inputs to the Geant4 detectorsimulation Truth information regarding the neutrino originbaseline and energy are propagated along with the event foruse later in the oscillation analysis

53 Event Reconstruction The pulse reconstruction providesthe signal charge and time in each PMT The baseline mean(119861mean) and rms (119861rms) are computed using the full readout


window (256 ns) The integrated charge (119902) is defined as thesum of digital counts in each waveform sample over theintegration window once the pedestal has been subtractedFor each pulse reconstructed the start time is computed asthe time when the pulse reaches 20 of its maximum Thistime is then corrected by the PMT-to-PMT offsets obtainedwith the light injection system

Vertex reconstruction in Double Chooz is not used forevent selection but is used for event energy reconstruction Itis based on amaximum charge and time likelihood algorithmwhich utilizes all hit and no-hit information in the detectorThe performance of the reconstruction has been evaluated insitu using radioactive sources deployed at known positionsalong the 119911-axis in the target volume and off-axis in the guidetubes The sources are reconstructed with a spatial resolutionof 32 cm for 137Cs 24 cm for 60Co and 22 cm for 68Ge

Cosmic muons passing through the detector or thenearby rock induce backgrounds which are discussed laterThe IV trigger rate is 46 sminus1 Allmuons in the ID are tagged bythe IV except some stoppingmuonswhich enter the chimneyMuons which stop in the ID and their resulting Michel 119890can be identified by demanding a large energy deposition(roughly a few tens of MeV) in the ID An event is tagged asa muon if there is gt5MeV in the IV or gt30MeV in the ID

The visible energy (119864vis) provides the absolute calorimet-ric estimation of the energy deposited per trigger 119864vis is afunction of the calibrated 119875119864 (total number of photoelec-trons)

119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)

where 119875119864 = sum119894119901119890119894= sum119894119902119894gain119894(119902119894) Coordinates in the

detector are 120588 and 119911 119905 is time 119898 refers to data or MonteCarlo (MC) and 119894 refers to each good channelThe correctionfactors 119891

119906 119891119904 and 119891MeV correspond respectively to the

spatial uniformity time stability and photoelectron per MeVcalibrations Four stages of calibration are carried out torender 119864vis linear independent of time and position andconsistent between data and MC Both the MC and data aresubjected to the same stages of calibration The sum over allgood channels of the reconstructed raw charge (119902

119894) from the

digitized waveforms is the basis of the energy estimationThe119875119864 response is position dependent for both MC and dataCalibration maps were created such that any 119875119864 response forany event located at any position (120588 119911) can be converted intoits response as ifmeasured at the center of the detector (120588 = 0119911 = 0) 119875119864119898

⨀= 119875119864119898(120588 119911) times 119891

119898

119906(120588 119911) The calibration maprsquos

correction for each point is labeled 119891119898

119906(120588 119911) Independent

uniformity calibration maps 119891119898119906(120588 119911) are created for data

and MC such that the uniformity calibration serves tominimize any possible difference in position dependenceof the data with respect to MC The capture peak on H(2223MeV) of neutrons from spallation and antineutrinointeractions provides a precise and copious calibration sourceto characterize the response nonuniformity over the fullvolume (both NT and GC)

The detector response stability was found to vary in timedue to two effects which are accounted for and corrected bythe term119891

119898

119904(119905) First the detector response can change due to

Table 7 Energy scale systematic errors

Error ()Relative nonuniformity 043Relative instability 061Relative nonlinearity 085Total 113

variations in readout gain or scintillator response This effecthas beenmeasured as a +22monotonic increase over 1 yearusing the response of the spallation neutrons capturing onGdwithin theNT Second few readout channels varying overtime are excluded from the calorimetry sum and the averageoverall response decreases by 03 per channel excludedTherefore any response119875119864

⨀(119905) is converted to the equivalent

response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined

as the day of the first Cf source deployment during August2011The remaining instability after calibration is used for thestability systematic uncertainty estimation

Thenumber119875119864⨀1199050

perMeV is determined by an absoluteenergy calibration independently for the data and MCThe response in 119875119864

⨀1199050for H capture as deployed in the

center of the NT is used for the absolute energy scale Theabsolute energy scales are found to be 2299 119875119864

⨀1199050MeV

and 2277119875119864⨀1199050

MeV respectively for the data and MCdemonstrating agreement within 1 prior to this calibrationstage

Discrepancies in response between the MC and dataafter calibration are used to estimate these uncertaintieswithin the prompt energy range and the NT volume Table 7summarizes the systematic uncertainty in terms of theremaining nonuniformity instability and nonlinearity Therelative nonuniformity systematic uncertainty was estimatedfrom the calibration maps using neutrons capturing onGd after full calibration The rms deviation of the relativedifference between the data andMC calibration maps is usedas the estimator of the nonuniformity systematic uncertaintyand is 043 The relative instability systematic error dis-cussed above is 061 A 085 variation consistent withthis nonlinearity was measured with the 119911-axis calibrationsystem and this is used as the systematic error for relativenonlinearity in Table 7 Consistent results were obtainedwhen sampling with the same sources along the GT

54 Neutrino Data Analysis Signals and Backgrounds The ]119890

candidate selection is as follows Events with an energy below05MeV where the trigger efficiency is not 100 or identifiedas light noise (119876max119876tot gt 009 or rms(119905start) gt 40 ns) arediscarded Triggers within a 1ms window following a taggedmuon are also rejected in order to reduce the correlated andcosmogenic backgrounds The effective veto time is 44 ofthe total run time Defining Δ119879 equiv 119905delayed minus 119905prompt furtherselection consists of 4 cuts

(1) time difference between consecutive triggers (promptand delayed) 2 120583s lt Δ119879 lt 100 120583s where the lowercut reduces correlated backgrounds and the upper cut


Table 8 Cuts used in the event selection and their efficiency for IBDevents The OV was working for the last 689 of the data

Cut Efficiency 119864prompt 1000 plusmn 00119864delayed 941 plusmn 06Δ119879 962 plusmn 05Multiplicity 995 plusmn 00Muon veto 908 plusmn 00Outer veto 999 plusmn 00

is determined by the approximately 30 120583s capture timeon Gd

(2) prompt trigger 07MeV lt 119864prompt lt 122MeV(3) delayed trigger 60MeV lt 119864delayed lt 120MeV and

119876max119876tot lt 0055(4) multiplicity no additional triggers from 100 120583s pre-

ceding the prompt signal to 400 120583s after it with thegoal of reducing the correlated background

The IBD efficiencies for these cuts are listed in Table 8A preliminary sample of 9021 candidates is obtained

by applying selections (1ndash4) In order to reduce the back-ground contamination in the sample candidates are rejectedaccording to two extra cuts First candidates within a 05 swindow after a high energy muon crossing the ID (119864

120583gt

600MeV) are tagged as cosmogenic isotope events and arerejected increasing the effective veto time to 92 Secondcandidates whose prompt signal is coincident with an OVtrigger are also excluded as correlated background Applyingthe above vetoes yields 8249 candidates or a rate of 362 plusmn 04eventsday uniformly distributed within the target for ananalysis livetime of 22793 days Following the same selectionprocedure on the ]

119890MC sample yields 84396 expected events

in the absence of oscillationThemain source of accidental coincidences is the random

association of a prompt trigger fromnatural radioactivity anda later neutron-like candidate This background is estimatednot only by applying the neutrino selection cuts describedbut also using coincidence windows shifted by 1 s in orderto remove correlations in the time scale of n-captures in Hand Gd The radioactivity rate between 07 and 122MeV is82 sminus1 while the singles rate in 6ndash12MeV energy region is18 hminus1 Finally the accidental background rate is found to be0261 plusmn 0002 events per day

The radioisotopes 8He and 9Li are products of spallationprocesses on 12C induced by cosmic muons crossing thescintillator volume The 120573-119899 decays of these isotopes consti-tute a background for the antineutrino search 120573-119899 emitterscan be identified from the time and space correlations totheir parent muon Due to their relatively long lifetimes(9Li 120591 = 257ms 8He 120591 = 172ms) an event-by-eventdiscrimination is not possible For the muon rates in ourdetector vetoing for several isotope lifetimes after eachmuonwould lead to an unacceptably large loss in exposure Insteadthe rate is determined by an exponential fit to the Δ119905

120583] equiv

119905120583minus 119905] profile of all possible muon-IBD candidate pairs The

analysis is performed for three visible energy 119864vis120583

ranges thatcharacterize subsamples of parent muons by their energydeposition not corrected for energy nonlinearities in the IDas follows

(1) Showering muons crossing the target value are sele-cted by119864vis

120583gt 600MeV and feature they an increased

probability to produce cosmogenic isotopesThe Δ119905120583]

fit returns a precise result of 095plusmn011 eventsday forthe 120573-119899-emitter rate

(2) In the 119864vis120583

range from 275 to 600MeV muonscrossing GC and target still give a sizable contributionto isotope production of 108 plusmn 044 eventsday Toobtain this result from a Δ119905

120583] fit the sample of muon-IBD pairs has to be cleaned by a spatial cut onthe distance of closest approach from the muon tothe IBD candidate of 119889

120583] lt 80 cm to remove themajority of uncorrelated pairs The correspondingcut efficiency is determined from the lateral distanceprofile obtained for 119864vis

120583gt 600MeV The approach is

validated by a comparative study of cosmic neutronsthat show an almost congruent profile with very littledependence on 119864vis

120583above 275MeV

(3) The cut 119864vis120583

lt 275MeV selects muons crossingonly the buffer volume or the rim of the GC Forthis sample no production of 120573-119899 emitters inside thetarget volume is observed An upper limit of lt03eventsday can be established based on a Δ119905

120583] fitfor 119889120583] lt 80 cm Again the lateral distribution of

cosmic neutrons has been used for determining thecut efficiency

The overall rate of 120573119899 decays found is 205+062minus052

eventsdayMost correlated backgrounds are rejected by the 1ms veto

time after each tagged muon The remaining events arisefrom cosmogenic events whose parent muon either missesthe detector or deposits an energy low enough to escapethe muon tagging Two contributions have been found fastneutrons (FNs) and stopping muons (SMs) FNs are createdby muons in the inactive regions surrounding the detectorTheir large interaction length allows them to cross thedetector and capture in the ID causing both a prompt triggerby recoil protons and a delayed trigger by capture on GdAn approximately flat prompt energy spectrum is expecteda slope could be introduced by acceptance and scintillatorquenching effects The time and spatial correlations distribu-tion of FN are indistinguishable from those of ]

119890events The

selected SM arise frommuons entering through the chimneystopping in the top of the ID and eventually decaying Theshort muon track mimics the prompt event and the decayMichel electron mimics the delayed event SM candidates arelocalized in space in the top of the ID under the chimneyand have a prompt-delayed time distribution following the22 120583s muon lifetime The correlated background has beenstudied by extending the selection on 119864prompt up to 30 MeVNo IBD events are expected in the interval 12MeV le

119864prompt le 30MeV FN and SM candidates were separated viatheir different correlation time distributions The observed


Table 9 Summary of observed IBD candidates with correspondingsignal and background predictions for each integration periodbefore any oscillation fit results have been applied

Reactors One reactor Totalboth on 119875th lt 20

Livetime (days) 13927 8866 22793IBD candidates 6088 2161 8249] Reactor B1 29109 7746 36855] Reactor B2 34224 13317 47541Cosmogenic isotope 1741 1108 2849Correlated FN and SM 933 594 1527Accidentals 364 231 595Total prediction 66371 22997 89368

prompt energy spectrum is consistent with a flat continuumbetween 12 and 30MeV which extrapolated to the IBD selec-tion window provideing a first estimation of the correlatedbackground rate of asymp075 eventsday The accuracy of thisestimate depends on the validity of the extrapolation of thespectral shape Several FN and SM analyses were performedusing different combinations of IV and OV taggings Themain analysis for the FN estimation relies on IV taggingof the prompt triggers with OV veto applied for the IBDselection A combined analysis was performed to obtain thetotal spectrum and the total rate estimation of both FN andSM (067 plusmn 020) eventsday summarized in Table 9

There are four ways that can be utilized to estimatebackgrounds Each independent background component canbe measured by isolating samples and subtracting possiblecorrelations Second we can measure each independentbackground component including spectral informationwhenfitting for 120579

13oscillations Third the total background rate is

measured by comparing the observed and expected rates asa function of reactor power Fourth we can use the both-reactor-off data to measure both the rate and spectrumThe latter two methods are used currently as cross-checksfor the background measurements due to low statisticsand are described here The measured daily rate of IBDcandidates as a function of the no-oscillation expected ratefor different reactor power conditions is shown in Figure 17The extrapolation to zero reactor power of the fit to thedata yields 29 plusmn 11 events per day in excellent agreementwith our background estimate The overall rate of correlatedbackground events that pass the IBD cuts is independentlyverified by analyzing 225 hours of both-reactors-off data[48] The expected neutrino signal is lt03 residual ]

119890events

Calibration data taken with the 252Cf source were usedto check the Monte Carlo prediction for any biases in theneutron selection criteria and estimate their contributions tothe systematic uncertainty

The fraction of neutron captures on gadolinium is evalu-ated to be 865 near the center of the target and to be 15lower than the fraction predicted by simulation Thereforethe Monte Carlo simulation for the prediction of the numberof ]119890events is reduced by factor of 0985 After the prediction

of the fraction of neutron captures on gadolinium is scaled

0

10

20

30

40

50

DataNo oscillation

Best fit90 CL interval

Obs

erve

d ra

te (d

ayminus1)

0 10 20 30 40 50Expected rate (dayminus1)

Figure 17 Daily number of ]119890candidates as a function of the

expected number of ]119890 The dashed line shows the fit to the data

along with the 90 C L bandThe dotted line shows the expectationin the no-oscillation scenario

to the data the prediction reproduces the data within 03under variation of selection criteria

The 252Cf is also used to check the neutron capture timeΔ119879 The simulation reproduces the efficiency (962) of theΔ119905119890+119899cut with an uncertainty of 05 augmentedwith sources

deployed through the NT and GCThe efficiency for Gd capture events with visible energy

greater than 4MeV to pass the 6MeV cut is estimated to be941 Averaged over theNT the fraction of neutron captureson Gd accepted by the 60MeV cut is in agreement withcalibration data within 07

The Monte Carlo simulation indicates that the numberof IBD events occurring in the GC with the neutron cap-tured in the NT (spill-in) slightly exceeds the number ofevents occurring in the target with the neutron escaping tothe gamma catcher (spill-out) by 135 plusmn 004 (stat) plusmn030(sys) The spill-inout effect is already included in thesimulation and therefore no correction for this is neededThe uncertainty of 03 assigned to the net spill-inoutcurrent was quantified by varying the parameters affectingthe process such as gadolinium concentration in the targetscintillator and hydrogen fraction in the gamma-catcher fluidwithin its tolerances Moreover the parameter variation wasperformed with multiple Monte Carlo models at low neutronenergies

55 Oscillation Analysis The oscillation analysis is based ona combined fit to antineutrino rate and spectral shape Thedata are compared to theMonte Carlo signal and backgroundevents from high-statistics samples The same selections areapplied to both signal and background with correctionsmade to Monte Carlo only when necessary to match detector


performance metrics The oscillation analysis begins byseparating the data into 18 variably sized bins between 07 and122MeV Two integration periods are used in the fit to helpseparate background and signal fluxes One set contains dataperiods where one reactor is operating at less than 20 of itsnominal thermal power according to power data provided byEDF while the other set contains data from all other timestypically when both reactors are running All data end upin one of the two integration periods Here we denote thenumber of observed IBD candidates in each of the bins as119873

119894

where 119894 runs over the combined 36 bins of both integrationperiods The use of multiple periods of data integration takesadvantage of the different signalbackground ratios in eachperiod as the signal rate varies with reactor power whilethe backgrounds remain constant in time This techniqueadds information about background behavior to the fit Thedistribution of IBD candidates between the two integrationperiods is given in Table 9 A prediction of the observednumber of signal and background events is constructedfor each energy bin following the same integration perioddivision as the following data

119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894

119875]119890rarr ]119890is the neutrino

survival probability from thewell-known oscillation formulaand 119873exp119877

119894is given by (16) The index 119887 runs over the three

backgrounds cosmogenic isotope correlated and accidentalThe index 119877 runs over the two reactors Chooz B1 andB2 Background populations were calculated based on themeasured rates and the livetime of the detector duringeach integration period Predicted populations for both null-oscillation signal and backgrounds may be found in Table 9

Systematic and statistical uncertainties are propagated tothe fit by the use of a covariance matrix 119872

119894119895in order to

properly account for correlations between energy bins Thesources of uncertainty 119860 are listed in Table 10 as follows

119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895

)119860on the right-hand

side of (18) represents the covariance of119873pred119894

and119873pred119895

dueto uncertainty 119860 The normalization uncertainty associatedwith each of the matrix contributions may be found from thesum of each matrix these are summarized in Table 10 Manysources of uncertainty contain spectral shape componentswhich do not directly contribute to the normalization errorbut do provide for correlated uncertainties between theenergy bins The signal covariance matrix119872sig

119894119895is calculated

taking into account knowledge about the predicted neutrinospectra The 9Li matrix contribution contains spectral shapeuncertainties estimated using different Monte Carlo eventgeneration parameters The slope of the FNSM spectrumis allowed to vary from a nearly flat spectrum Since acci-dental background uncertainties are measured to a high

Table 10 Summary of signal and background normalization uncer-tainties in this analysis relative to the total prediction

Source Uncertainty ()Reactor flux 167Detector response 032Statistics 106Efficiency 095Cosmogenic isotope background 138FNSM 051Accidental background 001Total 266

precision from many off-time windows they are included asa diagonal covariance matrix The elements of the covariancematrix contributions are recalculated as a function of theoscillation and other parameters (see below) at each step ofthe minimization This maintains the fractional systematicuncertainties as the bin populations vary from the changesin the oscillation and fit parameters

A fit of the binned signal and background data to a two-neutrino oscillation hypothesis was performed by minimiz-ing a standard 1205942 function

1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879

+(120598FNSM minus 1)

2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)

The use of energy spectrum information in this analysisallows additional information on background rates to begained from the fit in particular because of the small numberof IBD events between 8 and 12MeV The two fit parameters120598FNSM and 120598 9Li are allowed to vary as part of the fit andthey scale the rates of the two backgrounds (correlated andcosmogenic isotopes) The rate of accidentals is not allowedto vary since its initial uncertainty is precisely determined in-situ The energy scale for predicted signal and 9Li events isallowed to vary linearly according to the 120572

119864parameter with

an uncertainty 120590120572119864= 113 A final parameter constrains the

mass splitting Δ119898231

using the MINOS measurement [90] ofΔ1198982

31= (232 plusmn 012)times10

minus3 eV2 where we have symmetrizedthe error This error includes the uncertainty introduced byrelating the effective mass-squared difference observed in a]120583disappearance experiment to the one relevant for reactor

experiments and the ambiguity due to the type of the neutrinomass hierarchy see for example [91] Uncertainties for theseparameters 120590FNSM 120590 9Li and 120590MINOS are listed as the initialvalues in Table 11 The best fit gives sin22120579

13= 0109 plusmn

0030(stat) plusmn 0025(syst) at Δ119898231

= 232 times 10minus3 eV2 with

a 1205942NDF = 42135 Table 11 gives the resulting values ofthe fit parameters and their uncertainties Comparing the


2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)

Double Chooz 2012 dataNo-oscillation best-fit backgroundsBest fit sin2(212057913) = 0109at Δ1198982

31 = 000232 eV2

Summed backgrounds (see insets)

Lithium 9Fast 119899 and stopping 120583Accidentals

One reactor lt 20 power

(1205942dof = 42135)

Figure 18 Measured prompt energy spectrum for each integration period (data points) superimposed on the expected prompt energyspectrum including backgrounds (green region) for the no-oscillation (blue dotted curve) and best-fit (red solid curve) backgrounds atsin22120579

13= 0109 and Δ1198982

31= 232 times 10

minus3eV2 Inset stacked spectra of backgrounds Bottom differences between data and no-oscillationprediction (data points) and differences between best-fit prediction and no-oscillation prediction (red curve) The orange band representsthe systematic uncertainties on the best-fit prediction

Table 11 Parameters in the oscillation fit Initial values are deter-mined bymeasurements of background rates or detector calibrationdata Best-fit values are outputs of the minimization procedure

Fit parameter Initial value Best-fit value9Li Bkg 1205989Li (125 plusmn 054) dminus1 (100 plusmn 029) dminus1

FNSM Bkg 120598FNSM (067 plusmn 020) dminus1 (064 plusmn 013) dminus1

Energy scale 120572119864

1000 plusmn 0011 0986 plusmn 0007Δ1198982

31(10minus3 eV2) 232 plusmn 012 232 plusmn 012

values with the ones used as input to the fit in Table 9we conclude that the background rate and uncertainties arefurther constrained in the fit as well as the energy scale

The final measured spectrum and the best-fit spectrumare shown in Figure 18 for the new and old data sets and forboth together in Figure 19

An analysis comparing only the total observed numberof IBD candidates in each integration period to the expec-tations produces a best fit of sin22120579

13= 0170 plusmn 0052 at

1205942NDF = 0501 The compatibility probability for the

rate-only and rate+shape measurements is about 30 depe-

nding on how the correlated errors are handled between thetwo measurements

Confidence intervals for the standard analysis were deter-mined using a frequentist technique [92] This approachaccommodates the fact that the true 1205942 distributions may notbe Gaussian and is useful for calculating the probability ofexcluding the no-oscillation hypothesisThis study comparedthe data to 10000 simulations generated at each of 21 testpoints in the range 0 le sin22120579

13le 025 A Δ120594

2 statisticequal to the difference between the 1205942 at the test point andthe 1205942 at the best fit was used to determine the region insin22120579

13where the Δ1205942 of the data was within the given

confidence probability The allowed region at 68 (90) CLis 0068 (0044) lt sin22120579

13lt 015 (017) An analogous

technique shows that the data exclude the no-oscillationhypothesis at 999 (31120590)

6 RENO

The reactor experiment for neutrino oscillation (RENO) hasobtained a definitive measurement of the smallest neutrino


Double Chooz 2012 total dataNo-oscillation best-fit backgroundsBest fit sin2(212057913) = 0109

at Δ119898231 = 000232 eV2

from fit to two integration periodsSummed backgrounds (see insets)Lithium 9Fast 119899 and stopping 120583Accidentals

2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)

Figure 19 Sum of both integration periods plotted in the samemanner as Figure 18

mixing angle of 12057913

by observing the disappearance of elec-tron antineutrinos emitted from a nuclear reactor excludingthe no-oscillation hypothesis at 49120590 From the deficit thebest-fit value of sin22120579

13is obtained as 0113 plusmn 0013(stat) plusmn

0019(syst) based on a rate-only analysisConsideration of RENO began in early 2004 and its

proposal was approved by the Ministry of Science andTechnology in Korea in May 2005 The company operatingthe Yonggwang nuclear power plant KHNP has allowed usto carry out the experiment in a restricted area The projectstarted in March 2006 Geological survey was completedin 2007 Civil construction began in middle 2008 and wascompleted in early 2009 Both near and far detectors arecompleted in early 2011 and data taking began in earlyAugust2011 RENO is the first experiment to measure 120579

13with two

identical detectors in operation

61 Experimental Setup and Detection Method RENOdetects antineutrinos from six reactors at YonggwangNuclear Power Plant in Korea A symmetric arrangement ofthe reactors and the detectors as shown in Figure 20 is usefulfor minimizing the complexity of the measurement The

Figure 20 A schematic setup of the RENO experiment

six pressurized water reactors with each maximum thermaloutput of 28GWth (reactors 3 4 5 and 6) or 266 GWth(reactors 1 and 2) are lined up in roughly equal distances andspan sim13 km

Two identical antineutrino detectors are located at 294mand 1383m respectively from the center of reactor arrayto allow a relative measurement through a comparison ofthe observed neutrino rates The near detector is locatedinside a resticted area of the nuclear power plant quiteclose to the reactors to make an accurate measurementof the antineutrino fluxes before their oscillations The far(near) detector is beneath a hill that provides 450m (120m)of water-equivalent rock overburden to reduce the cosmicbackgrounds

The measured far-to-near ratio of antineutrino fluxescan considerably reduce systematic errors coming fromuncertainties in the reactor neutrino flux target mass anddetection efficiencyThe relativemeasurement is independentof correlated uncertainties and helps to minimize uncorre-lated reactor uncertainties

The positions of two detectors and six reactors aresurveyedwithGPS and total station to determine the baselinedistances between detector and reactor to an accuracy ofless than 10 cm The accurate measurement of the baselinedistances finds the reduction of reactor neutrino fluxes atdetector to a precision of much better than 01The reactor-flux-weighted baseline is 40856m for the near detector and144399m for the far detector

62 Detector Each RENO detector (Figure 21) consists of amain inner detector (ID) and an outer veto detector (OD)The main detector is contained in a cylindrical stainlesssteel vessel that houses two nested cylindrical acrylic ves-sels The innermost acrylic vessel holds 186m3 (165 t) sim01 Gadolinium-(Gd-) doped liquid scintillator (LS) as aneutrino target An electron antineutrino can interact witha free proton in LS ]

119890+ 119901 rarr 119890

++ 119899 The coincidence of

a prompt positron signal and a delayed signal from neutroncapture by Gd provides the distinctive signature of inverse 120573decay


Figure 21 A schematic view of the RENOdetectorThe near and fardetectors are identical

The central target volume is surrounded by a 60 cm thicklayer of LS without Gd useful for catching 120574-rays escapingfrom the target region and thus increasing the detectionefficiency Outside this 120574-catcher a 70 cm thick buffer layerof mineral oil provides shielding from radioactivity in thesurrounding rocks and in the 354 10-inch photomultipliers(PMTs) that are mounted on the inner wall of the stainlesssteel container

The outermost veto layer of OD consists of 15m of highlypurifiedwater in order to identify events coming fromoutsideby their Cherenkov radiation and to shield against ambient 120574-rays and neutrons from the surrounding rocks

The LS is developed and produced as a mixture of linearalkyl benzene (LAB) PPO and bis-MSB A Gd-carboxylatecomplex using TMHAwas developed for the best Gd loadingefficiency into LS and its long-term stability Gd-LS and LSare made and filled into the detectors carefully to ensure thatthe near and far detectors are identical

63 Data Sample In the 229 day data-taking period between11 August 2011 to 26 March 2012 the far (near) detectorobserved 17102 (154088) electron antineutrino candidateevents or 7702 plusmn 059 (8008 plusmn 20) eventsday with abackground fraction of 55 (27) During this period allsix reactors were mostly on at full power and reactors 1 and 2were off for a month each because of fuel replacement

Event triggers are formed by the number of PMTs withsignals above a sim03 photoelectron (pe) threshold (NHIT)An event is triggered and recorded if the ID NHIT islarger than 90 corresponding to 05sim06MeV well below the102MeV as the minimum energy of an IBD positron signalor if the OD NHIT is larger than 10

The event energy is measured based on the total charge(119876tot) in pe collected by the PMTs and corrected for gainvariation The energy calibration constant of 250 pe per MeVis determined by the peak energies of various radioactivesources deployed at the center of the target

Table 12 Event rates of the observed candidates and the estimatedbackground

Detector Near FarSelected events 154088 17102Total background rate (per day) 2175 plusmn 593 424 plusmn 075

IBD rate after background77905 plusmn 626 7278 plusmn 095

subtraction (per day)DAQ Livetime (days) 19242 22206Detection efficiency (120598) 0647 plusmn 0014 0745 plusmn 0014

Accidental rate (per day) 430 plusmn 006 068 plusmn 003

9Li8He rate (per day) 1245 plusmn 593 259 plusmn 075

Fast neutron rate (per day) 500 plusmn 013 097 plusmn 006

64 Background In the final data samples uncorrelated(accidentals) and correlated (fast neutrons fromoutside of IDstopping muon followers and 120573-n emitters from 9Li 8He)background events survive selection requirements The totalbackground rate is estimated to be 2175 plusmn 593 (near) or424 plusmn 075 (far) events per day and summarized in Table 12

The uncorrelated background is due to accidental coin-cidences from random association of a prompt-like eventdue to radioactivity and a delayed-like neutron capture Theremaining rate in the final sample is estimated to be 430 plusmn006 (near) or 068 plusmn 003 (far) events per day

The 9Li 8He 120573-n emitters are mostly produced byenergetic muons because their production cross-sections incarbon increase with muon energy The background rate inthe final sample is obtained as 1245plusmn593 (near) or 259plusmn075(far) events per day from a fit to the delay time distributionwith an observed mean decay time of sim250ms

An energetic neutron entering the ID can interact in thetarget to produce a recoil proton before being captured onGd Fast neutrons are produced by cosmic muons traversingthe surrounding rock and the detector The estimated fastneutron background is 500 plusmn 013 (near) or 097 plusmn 006 (far)events per day

65 Systematic Uncertainty The combined absolute uncer-tainty of the detection efficiency is correlated between thetwo detectors and estimated to be 15 Uncorrelated relativedetection uncertainties are estimated by comparing the twoidentical detectors They come from relative differencesbetween the detectors in energy scale target protons Gd cap-ture ratio and others The combined uncorrelated detectionuncertainty is estimated to be 02

The uncertainties associated with thermal power andrelative fission fraction contribute to 09 of the ]

119890yield

per core to the uncorrelated uncertainty The uncertaintiesassociated with ]

119890yield per fission fission spectra and

thermal energy released per fission result in a 20 correlateduncertaintyWe assume a negligible contribution of the spentfuel to the uncorrelated uncertainty

66 Results All reactors were mostly in steady operationat the full power during the data-taking period except forreactor 2 (R2) whichwas off for themonth of September 2011

24 Advances in High Energy PhysicsIB

D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Figure 22 Measured daily-average rates of reactor neutrinos afterbackground subtraction in the near and far detectors as a functionof running time The solid curves are the predicted rates for nooscillation

and reactor 1 (R1) which was off from February 23 2012 forfuel replacement Figure 22 presents the measured daily ratesof IBD candidates after background subtraction in the nearand far detectorsThe expected rates assuming no oscillationobtained from the weighted fluxes by the thermal power andthe fission fractions of each reactor and its baseline to eachdetector are shown for comparison

Based on the number of events at the near detector andassuming no oscillation RENO finds a clear deficit with afar-to-near ratio

119877 = 0920 plusmn 0009 (stat) plusmn 0014 (syst) (20)


is determined from a 1205942 fit withpull terms on the uncorrelated systematic uncertainties Thenumber of events in each detector after the backgroundsubtraction has been compared with the expected numberof events based on the reactor neutrino flux detectionefficiency neutrino oscillations and contribution from thereactors to each detector determined by the baselines andreactor fluxes

The best-fit value thus obtained is


and it excludes the no-oscillation hypothesis at the 49standard deviation level

RENO has observed a clear deficit of 80 for the fardetector and of 12 for the near detector concluding adefinitive observation of reactor antineutrino disappearanceconsistent with neutrino oscillationsThe observed spectrumof IBD prompt signals in the far detector is compared to thenon oscillation expectations based on measurements in thenear detector in Figure 23 The spectra of prompt signals areobtained after subtracting backgrounds shown in the insetThe disagreement of the spectra provides further evidence ofneutrino oscillation

0

500

1000

Far detectorNear detector

Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV

Fast neutronAccidental9Li8He

(a)

1050Prompt energy (MeV)

Far

near

08

1

12

(b)

Figure 23 Observed spectrum of the prompt signals in the fardetector compared with the nonoscillation predictions from themeasurements in the near detector The backgrounds shown in theinset are subtracted for the far spectrumThe background fraction is55 (27) for far (near) detector Errors are statistical uncertaintiesonly (b) The ratio of the measured spectrum of far detector to thenon-oscillation prediction

In summary RENO has observed reactor antineutrinosusing two identical detectors each with 16 tons of Gd-loadedliquid scintillator and a 229 day exposure to six reactorswith total thermal energy of 165 GWth In the far detectora clear deficit of 80 is found by comparing a total of17102 observed events with an expectation based on thenear detector measurement assuming no oscillation Fromthis deficit a rate-only analysis obtains sin22120579

13= 0113 plusmn

0013 (stat) plusmn 0019 (syst) The neutrino mixing angle 12057913is

measured with a significance of 49 standard deviation

67 Future Prospects and Plan RENO has measured thevalue of sin22120579

13with a total error of plusmn0023 The expected

sensitivity of RENO is to obtain plusmn001 for the error based onthe three years of data leading to a statistical error of 0006and a systematic error of sim0005

The fast neutron and 9Li8He backgrounds produced bycosmic muons depend on the detector sites having differentoverburdens Therefore their uncertainties are the largest


contribution to the uncorrelated error in the current resultand change the systematic error by 0017 at the best-fit value

RENO makes efforts on further reduction of back-grounds especially by removing the 9Li8He background by atighter muon veto requirement and a spectral shape analysisto improve the systematic error A longer-term effort willbe made to reduce the systematic uncertainties of reactorneutrino flux and detector efficiency

7 The Reactor Antineutrino Anomaly-Thierry

71 New Predicted Cross-Section per Fission Fission reactorsrelease about 1020 ]

119890GWminus1sminus1 which mainly come from the

beta decays of the fission products of 235U 238U 239Pu and241Pu The emitted antineutrino spectrum is then given by119878tot(119864]) = sum

119896119891119896119878119896(119864]) where 119891119896 refers to the contribution

of the main fissile nuclei to the total number of fissions of thekth branch and 119878

119896to their corresponding neutrino spectrum

per fission Antineutrino detection is achieved via the inversebeta-decay (IBD) reaction ]

119890+1H rarr 119890

++ 119899 Experiments

at baselines below 100m reported either the ratios (119877) ofthe measured to predicted cross-section per fission or theobserved event rate to the predicted rate

The event rate at a detector is predicted based on thefollowing formula

119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)

where the first term stands for the mean solid angle and 119873119901

is the number of target protons for the inverse beta-decayprocess of detectionThese two detector-related quantities areusually known with very good accuracy The last two termscome from the reactor side The ratio of 119875th the thermalpower of the reactor over ⟨119864

119891⟩ the mean energy per fission

provide the mean number of fissions in the core 119875th canbe known at the subpercent level in commercial reactorssomewhat less accurately at research reactors The meanenergy per fission is computed as the average over the fourmain fissioning isotopes accounting for 995 of the fissions

⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)

It is accurately known from the nuclear databases andstudy of all decays and neutron captures subsequent to afission [72] Finally the dominant source of uncertainty andby far the most complex quantity to compute is the meancross-section per fission defined as

120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896

is the predicted cross-sections for eachfissile isotope 119878tot is the model dependent reactor neutrino

spectrum for a given average fuel composition (119891119896) and 120590VminusA

is the theoretical cross-section of the IBD reaction

120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]

times 119864119890 [MeV] (1 + 120575rec + 120575wm + 120575rad)

(25)

where 120575rec 120575wm and 120575rad are respectively the nucleon recoilweak magnetism and radiative corrections to the cross-section (see [22 93] for details) The fraction of fissionsundergone by the kth isotope 119891

119896 can be computed at the few

percent level with reactor evolution codes (see for instance[79]) but their impact in the final error is well reduced by thesum rule of the total thermal power accurately known fromindependent measurements

Accounting for new reactor antineutrino spectra [32] thenormalization of predicted antineutrino rates120590pred

119891119896 is shifted

by+37+42+47 and+98 for 119896 =235U 239Pu 241Puand 238U respectively In the case of 238U the completenessof nuclear databases over the years largely explains the +98shift from the reference computations [22]

The new predicted cross-section for any fuel compositioncan be computed from (24) By default the new computationtakes into account the so-called off-equilibrium correction[22] of the antineutrino fluxes (increase in fluxes caused bythe decay of long-lived fission products) Individual cross-sections per fission per fissile isotope are slightly different by+125 for the averaged composition of Bugey-4 [10] withrespect to the original publication of the reactor antineu-trino anomaly [93] because of the slight upward shift ofthe antineutrino flux consecutive to the work of [32] (seeSection 22 for details)

72 Impact of the New Reactor Neutrino Spectra on Past Short-Baseline (lt100m) Experimental Results In the eighties andnineties experiments were performed with detectors locateda few tens of meters from nuclear reactor cores at ILLGoesgen Rovno Krasnoyarsk Bugey (phases 3 and 4) andSavannah River [7ndash15] In the context of the search of O(eV)sterile neutrinos these experiments with baselines below100m have the advantage that they are not sensitive to apossible 120579

13- Δ119898231-driven oscillation effect (unlike the Palo

Verde and CHOOZ experiments for instance)The ratios of observed event rates to predicted event

rates (or cross-section per fission) 119877 = 119873obs119873pred aresummarized in Table 13 The observed event rates andtheir associated errors are unchanged with respect tothe publications the predicted rates are reevaluatedseparately in each experimental case One can observea general systematic shift more or less significantlybelow unity These reevaluations unveil a new reactorantineutrino anomaly (httpirfuceafrenPhoceaVie des(labosAstast visuphpid ast=3045) [93] clearly illustratedin Figure 24 In order to quantify the statistical significanceof the anomaly one can compute the weighted average of theratios of expected-over-predicted rates for all short-baseline


Table 13 119873obs119873pred ratios based on old and new spectra Off-equilibrium corrections have been applied when justified The err columnis the total error published by the collaborations including the error on 119878tot and the corr column is the part of the error correlated amongexperiments (multiple baseline or same detector)

Result Det type 120591119899(s) 235U 239Pu 238U 241Pu Old New Err () Corr () 119871 (m)

Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18

Bugey-3-I 6Li-LS 889 0538 0328 0078 0056 0988 0930 48 48 15Bugey-3-II 6Li-LS 889 0538 0328 0078 0056 0994 0936 49 48 40Bugey-3-III 6Li-LS 889 0538 0328 0078 0056 0915 0861 141 48 95Goesgen-I 3He + LS 897 0620 0274 0074 0042 1018 0949 65 60 38Goesgen-II 3He + LS 897 0584 0298 0068 0050 1045 0975 65 60 45Goesgen-II 3He + LS 897 0543 0329 0070 0058 0975 0909 76 60 65ILL 3He + LS 889 ≃1 mdash mdash mdash 0832 07882 95 60 9Krasn I 3He + PE 899 ≃1 mdash mdash mdash 1013 0920 58 49 33Krasn II 3He + PE 899 ≃1 mdash mdash mdash 1031 0937 203 49 92Krasn III 3He + PE 899 ≃1 mdash mdash mdash 0989 0931 49 49 57SRP I Gd-LS 887 ≃1 mdash mdash mdash 0987 0936 37 37 18SRP II Gd-LS 887 ≃1 mdash mdash mdash 1055 1001 38 37 24ROVNO88-1I 3He + PE 8988 0607 0277 0074 0042 0969 0901 69 69 18ROVNO88-2I 3He + PE 8988 0603 0276 0076 0045 1001 0932 69 69 18ROVNO88-1S Gd-LS 8988 0606 0277 0074 0043 1026 0955 78 72 18ROVNO88-2S Gd-LS 8988 0557 0313 0076 0054 1013 0943 78 72 25ROVNO88-3S Gd-LS 8988 0606 0274 0074 0046 0990 0922 72 72 18

Distance to reactor (m)

Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103

Figure 24 Short-baseline reactor antineutrino anomaly The experimental results are compared to the prediction without oscillationtaking into account the new antineutrino spectra the corrections of the neutron mean lifetime and the off-equilibrium effects Publishedexperimental errors and antineutrino spectra errors are added in quadrature The mean-averaged ratio including possible correlations is0927 plusmn 0023 As an illustration the red line shows a 3 active neutrino mixing solution fitting the data with sin2(2120579

13) = 015 The blue line

displays a solution including a new neutrino mass state such as |Δ1198982new119877| ≫ 2 eV2 and sin2(2120579new119877) = 012 as well as sin2(212057913) = 0085

reactor neutrino experiments (including their possiblecorrelations)

In doing so the authors of [93] have considered the fol-lowing experimental rate information Bugey-4 andRovno91the three Bugey-3 experiments the three Goesgen experi-ments and the ILL experiment the three Krasnoyarsk exper-iments the two Savannah River results (SRP) and the fiveRovno88 experiments is the corresponding vector of 19ratios of observed-to-predicted event rates A 20 systematicuncertainty was assumed fully correlated among all 19 ratiosresulting from the common normalization uncertainty ofthe beta spectra measured in [19ndash21] In order to account

for the potential experimental correlations the experimentalerrors of Bugey-4 and Rovno91 of the three Goesgen andthe ILL experiments the three Krasnoyarsk experiments thefive Rovno88 experiments and the two SRP results were fullycorrelated Also the Rovno88 (1I and 2I) results were fullycorrelated with Rovno91 and an arbitrary 50 correlationwas added between the Rovno88 (1I and 2I) and the Bugey-4measurement These latest correlations are motivated by theuse of similar or identical integral detectors

In order to account for the non-Gaussianity of the ratios119877 a Monte Carlo simulation was developed to check thispoint and it was found that the ratios distribution is almost


Gaussian but with slightly longer tails which were taken intoaccount in the calculations (in contours that appear latererror bars are enlarged) With the old antineutrino spectrathe mean ratio is 120583 = 0980 plusmn 0024

With the new antineutrino spectra one obtains 120583 =

0927 plusmn 0023 and the fraction of simple Monte Carloexperiments with 119903 ge 1 is 03 corresponding to a minus29120590effect (while a simple calculation assuming normality wouldlead to minus32120590) Clearly the new spectra induce a statisticallysignificant deviation from the expectation This motivatesthe definition of an experimental cross-section 120590

ano2012119891

=

0927 times 120590prednew119891

With the new antineutrino spectra theminimum 120594

2 for the data sample is 1205942mindata = 184 Thefraction of simple Monte Carlo experiments with 120594

2

min lt

1205942

mindata is 50 showing that the distribution of experimentalratios in around the mean value is representative given thecorrelations

Assuming the correctness of 120590prednew119891

the anomaly couldbe explained by a common bias in all reactor neutrinoexperiments The measurements used different detectiontechniques (scintillator counters and integral detectors)Neu-trons were tagged either by their capture in metal-loadedscintillator or in proportional counters thus leading totwo distinct systematics As far as the neutron detectionefficiency calibration is concerned note that different typesof radioactive sources emitting MeV or sub-MeV neutronswere used (Am-Be 252Cf Sb-Pu and Pu-Be) It should bementioned that the Krasnoyarsk ILL and SRP experimentsoperated with nuclear fuel such that the difference betweenthe real antineutrino spectrum and that of pure 235Uwas lessthan 15 They reported similar deficits to those observedat other reactors operating with a mixed fuel Hence theanomaly can be associated neither with a single fissile isotopenor with a single detection technique All these elementsargue against a trivial bias in the experiments but a detailedanalysis of the most sensitive of them involving expertswould certainly improve the quantification of the anomaly

The other possible explanation of the anomaly is basedon a real physical effect and is detailed in the next sectionIn that analysis shape information from the Bugey-3 andILL-published data [7 8] is used From the analysis of theshape of their energy spectra at different source-detectordistances [8 9] the Goesgen and Bugey-3 measurementsexclude oscillations with 006 lt Δ119898

2lt 1 eV2 for sin2(2120579) gt

005 Bugey-3rsquos 40m15m ratio data from [8] is used as itprovides the best limit As already noted in [94] the datafrom ILL showed a spectral deformation compatible with anoscillation pattern in their ratio of measured over predictedevents It should bementioned that the parameters best fittingthe data reported by the authors of [94] were Δ1198982 = 22 eV2and sin2(2120579) = 03 A reanalysis of the data of [94] was carriedout in order to include the ILL shape-only information in theanalysis of the reactor antineutrino anomaly The contour inFigure 14 of [7] was reproduced for the shape-only analysis(while for the rate-only analysis discussed above that of [94]was reproduced excluding the no-oscillation hypothesis at2120590)

73 The Fourth Neutrino Hypothesis (3 + 1 Scenario)

731 Reactor Rate-Only Analysis The reactor antineutrinoanomaly could be explained through the existence of a fourthnonstandard neutrino corresponding in the flavor basis to asterile neutrino ]

119904with a large Δ1198982new value

For simplicity the analysis presented here is restricted tothe 3 + 1 four-neutrino scheme in which there is a groupof three active neutrino masses separated from an isolatedneutrino mass such that |Δ1198982new| ≫ 10

minus2 eV2 The latterwould be responsible for very short-baseline reactor neutrinooscillations For energies above the IBD threshold and base-lines below 100m the approximated oscillation formula

119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)

is adopted where active neutrino oscillation effects areneglected at these short baselines In such a frameworkthe mixing angle is related to the 119880 matrix element by therelation

sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)

One can now fit the sterile neutrino hypothesis to thedata (baselines below 100m) by minimizing the least-squaresfunction

(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)

assuming sin2(212057913) = 0 Figure 25 provides the results of

the fit in the sin2(2120579new) minus Δ1198982

new plane including onlythe reactor experiment rate information The fit to the dataindicates that |Δ1198982new119877| gt 02 eV2 (99) and sin2(2120579new119877) sim014 The best-fit point is at |Δ1198982new119877| = 05 eV2 and sin2(2120579new119877) sim 014 The no-oscillation analysis is excluded at998 corresponding roughly to 3120590

732 Reactor Rate+Shape Analysis The ILL experimentmay have seen a hint of oscillation in their measuredpositron energy spectrum [7 94] but Bugey-3rsquos results donot point to any significant spectral distortion more than15m away from the antineutrino source Hence in a firstapproximation hypothetical oscillations could be seen as anenergy-independent suppression of the ]

119890rate by a factor

of (12)sin2(2120579new119877) thus leading to Δ1198982new119877 gt 1 eV2 andaccounting for the Bugey-3 and Goesgen shape analyses[8 9] Considering the weighted average of all reactorexperiments one obtains an estimate of the mixing anglesin2(2120579new119877) sim 015 The ILL positron spectrum is thus inagreement with the oscillation parameters found indepen-dently in the reanalyses mainly based on rate informationBecause of the differences in the systematic effects in therate and shape analyses this coincidence is in favor of atrue physical effect rather than an experimental anomalyIncluding the finite spatial extension of the nuclear reactorsand the ILL and Bugey-3 detectors it is found that the smalldimensions of the ILL nuclear core lead to small correctionsof the oscillation pattern imprinted on the positron spectrum


2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1

10minus110minus210minus3

10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )

1 dof Δ1205942 profile

1 do

fΔ1205942

profi

le

2 dof Δ1205942 contours

909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)

10510010minus110minus210minus3 Δ1205942

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)

Figure 25 (a) Allowed regions in the sin2(2120579new) minus Δ1198982

new plane obtained from the fit of the reactor neutrino data without any energyspectra information to the 3 + 1 neutrino hypothesis with sin2(2120579

13) = 0 The best-fit point is indicated by a star (b) Allowed regions in the

sin2(2120579new)minusΔ1198982

new plane obtained from the fit of the reactor neutrino data without ILL-shape information but with the stringent oscillationconstraint of Bugey-3 based on the 40m15 m ratios to the 3 + 1 neutrino hypothesis with sin2(2120579

13) = 0 The best-fit point is indicated by a

star

However the large extension of the Bugey nuclear core issufficient to wash out most of the oscillation pattern at 15mThis explains the absence of shape distortion in the Bugey-3experiment We now present results from a fit of the sterileneutrino hypothesis to the data including both Bugey-3 andILL original results (no-oscillation reported) With respect tothe rate only parameters the solutions at lower |Δ1198982new119877+119878|are now disfavored at large mixing angle because they wouldhave imprinted a strong oscillation pattern in the energyspectra (or their ratio) measured at Bugey-3 and ILL Thebest fit point is moved to |Δ1198982new119877+119878| = 24 eV2 whereas themixing angle remains almost unchanged at sin2(2120579new119877+S) sim014 The no-oscillation hypothesis is excluded at 996corresponding roughly to 29120590 Figure 25 provides the resultsof the fit in the sin2(2120579new)minusΔ119898

2

new plane including both thereactor experiment rate and shape (Bugey-3 and ILL) data

74 Combination of the Reactor and the GalliumAnomalies Itis also possible to combine the results on the reactor antineu-trino anomaly with the results on the gallium anomaly Thegoal is to quantify the compatibility of the reactor and thegallium data

For the reanalysis of the Gallex and Sage calibrationruns with 51Cr and 37Ar radioactive sources emitting sim1MeVelectron neutrinos [95ndash100] the methodology developed in[101] is used However in the analysis shown here possiblecorrelations between these four measurements are includedDetails are given in [93] This has the effect of being slightlymore conservative with the no-oscillation hypothesis dis-favored at 977 CL Gallex and Sage observed an averagedeficit of 119877

119866= 086 plusmn 006 (1120590) The best-fit point is at

|Δ1198982

gallium| = 24 eV2 (poorly defined) whereas the mixingangle is found to be sin2(2120579gallium) sim 027plusmn013 Note that thebest-fit values are very close to those obtained by the analysisof the rate+shape reactor data

Combing both the reactor and the gallium data The no-oscillation hypothesis is disfavored at 9997 CL (36120590)Allowed regions in the sin2(2120579new) minus Δ119898

2

new plane are dis-played in Figure 26 together with the marginal Δ1205942 profilesfor |Δ1198982new| and sin2(2120579new) The combined fit leads to thefollowing constraints on oscillation parameters |Δ1198982new| gt15 eV2 (99 CL) and sin2(2120579new) = 017 plusmn 004 (1120590) Themost probable |Δ119898

2

new| is now rather better defined withrespect to what has been published in [93] at |Δ1198982new| =

23 plusmn 01 eV2

75 Status of the Reactor Antineutrino Anomaly The impactof the new reactor antineutrino spectra has been extensivelystudied in [93]The increase of the expected antineutrino rateby about 45 combined with revised values of the antineu-trino cross-section significantly decreased the normalizedratio of observed-to-expected event rates in all previousreactor experiments performed over the last 30 years atdistances below 100m [7ndash15]The new average ratio updatedearly 2012 is now 0927 plusmn 0023 leading to an enhancementof reactor antineutrino anomaly now significant at the 3120590confidence levelThe best-fit point is at |Δ1198982new119877+119878| = 24 eV

2

whereas the mixing angle is at sin2(2120579new119877+119878) sim 014This deficit could still be due to some unknown in the

reactor physics but it can also be analyzed in terms of asuppression of the ]

119890rate at short distance as could be


2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast

Figure 26 Allowed regions in the sin2(2120579new) minus Δ1198982

new plane fromthe combination of reactor neutrino experiments the Gallex andSage calibration sources experiments and the ILL and Bugey-3-energy spectra The data are well fitted by the 3 + 1 neutrinohypothesis while the no-oscillation hypothesis is disfavored at9997 CL (36120590)

expected from a sterile neutrino beyond the standardmodelwith a large |Δ1198982new| ≫ |Δ119898

2

31| Note that hints of such results

were already present at the ILL neutrino experiment in 1981[94]

Considering the reactor ]119890anomaly and the gallium ]

119890

source experiments [95ndash101] together it is interesting to notethat in both cases (neutrinos and antineutrinos) comparabledeficits are observed at a similar 119871119864 Furthermore it turnsout that each experiment fitted separately leads to similarvalues of sin2(2120579new) and similar lower bounds for |Δ1198982new|but without a strong significance A combined global fit ofgallium data and of short-baseline reactor data taking intoaccount the reevaluation of the reactor results discussed hereas well as the existing correlations leads to a solution for anew neutrino oscillation such that |Δ1198982new| gt 15 eV2 (99CL) and sin2(2120579new) = 017 plusmn 004 (1120590) disfavoring theno-oscillation case at 9997 CL (36120590) The most probable|Δ1198982

new| is now at |Δ1198982new| = 23 plusmn 01 eV2 This hypothesisshould be checked against systematical effects either in theprediction of the reactor antineutrino spectra or in theexperimental results

8 Reactor Monitoring for Nonproliferation ofNuclear Weapons

In the past neutrino experiments have only been used forfundamental research but today thanks to the extraordinaryprogress of the field for example the measurement of theoscillation parameters neutrinos could be useful for society

The International Atomic Energy Agency (IAEA) workswith its member states to promote safe secure and peacefulnuclear technologies One of its missions is to verify that

safeguarded nuclear material and activities are not usedfor military purposes In a context of international tensionneutrino detectors could help the IAEA to verify the treatyon the non-proliferation of nuclear weapons (NPT) signedby 145 states around the world

A small neutrino detector located at a few tens of metersfrom a nuclear core couldmonitor nuclear reactor cores non-intrusively robustly and automatically Since the antineu-trino spectra and relative yields of fissioning isotopes 235U238U 239Pu and 241Pu depend on the isotopic compositionof the core small changes in composition could be observedwithout ever directly accessing the core itself Informationfrom a modest-sized antineutrino detector coupled with thewell-understood principles that govern the corersquos evolutionin time can be used to determine whether the reactor isbeing operated in an illegitimate way Furthermore such adetector can help to improve the reliability of the operationby providing an independent and accurate measurement inreal time of the thermal power and its reactivity at a levelof a few percent The intention is to design an ldquooptimalrdquomonitoring detector by using the experience obtained fromneutrino physics experiments and feasibility studies

Sands is a one cubic meter antineutrino detector locatedat 25 meters from the core of the San Onofre reactor sitein California [102] The detector has been operating forseveral months in an automatic and nonintrusive fashion thatdemonstrates the principles of reactor monitoring Althoughthe signal-to-noise ratio of the current design is still less thantwo it is possible to monitor the thermal power at a level of afew percent in two weeks At this stage of the work the studyof the evolution of the fuel seems difficult but this has alreadybeen demonstrated by the Bugey and Rovno experiments

The NUCIFER experiment in France [103] a 850 litersGd-doped liquid scintillator detector installed at 7m fromthe Osiris nuclear reactor core at CEA-Saclay The goal is themeasurement of its thermal power and plutonium contentThe design of such a small volume detector has been focusedon high detection efficiency and good background rejectionThe detector is being operated to since May 2012 and firstresults are expected in 2013

The near detectors of Daya Bay RENO and DoubleChooz will be a research detector with a very high sensitivityto study neutrino oscillations Millions of events are beingdetected in the near detectors (between 300 and 500m awayfrom the cores) These huge statistics could be exploited tohelp the IAEA in its safeguards missions The potential ofneutrinos to detect various reactor diversion scenariorsquos canbe tested

A realistic reactor monitor is likely to be somewherebetween the two concepts presented above

9 Future Prospects

Reactors are powerful neutrino sources for free It is a wellunderstood source since the precision of the neutrino fluxand energy spectrum is better than 2 With a near detectorthis uncertainty can be reduced to 03 Clearly this is muchbetter than usual neutrinos sources such as accelerators solarand atmospheric neutrinos If a detector is placed at different


Figure 27 The new site for a long-baseline reactor neutrino exper-iment

baseline an experiment with different motivation can beplanned

91 Mass Hierarchy With the discovery of the unexpectedlarge 120579

13 mass hierarchy and even the CP phase become

accessible with nowadays technologies A number of newprojects are now proposed based on different neutrinosources and different types of detectors

It is known that neutrino mass hierarchy can be deter-mined by long-baseline (more than 1000 km) acceleratorexperiment through matter effects Atmospheric neutrinosmay also be used for this purpose using a huge detector Neu-trino mass hierarchy can in fact distort the energy spectrumfrom reactors [104 105] and a Fourier transformation of thespectrum can enhance the signature since mass terms appearin the frequency regime of the oscillation probability [106]

It is also shown that by employing a different Fouriertransformation as the following

FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)

the signature of mass hierarchy is more evident and it isindependent of the precise knowledge of Δ2

23[107]

The normal hierarchy and inverted hierarchy have verydifferent shapes of the energy spectrum after the Fouriertransformation A detailed Monte Carlo study [108] showsthat if sin22120579

13is more than (1-2) a (10ndash50) kt liquid scin-

tillator at a baseline of about 60 kmwith an energy resolutionbetter than (2-3) can determine the mass hierarchy at morethan 90 C L In fact with sin22120579

13= 01 the mass hierarchy

can be determined up to the 3120590 level with a nominal detectorsize of 20 kt and a detector energy resolution of 3

The group at the Institute of High Energy Physics inBeijing proposed such an experiment in 2008 Fortunately ata distance of 60 km from Daya Bay there is a mountain withoverburden more than 1500MWE where an undergroundlab can be built Moreover this location is 60 km fromanother nuclear power plant to be built as shown in Figure 27The total number of reactors 6 operational and 6 to be builtmay give a total thermal power of more than 35GW

Figure 28 A conceptual design of a large liquid scintillator detector

A conceptual design of the detector is shown in Figure 28The detector is 30m in diameter and 30m high filled with20 kt liquid scintillator The oil buffer will be 6 kt and waterbuffer is 10 kt The totally needed number of 2010158401015840 PMTs is15000 covering 80 of the surface area

There are actually two main technical difficulties for sucha detector The attenuation length of the liquid scintillatorshould be more than 30m and the quantum efficiency ofPMTs should be more than 40 RampD efforts are now startedat IHEP and results will be reported in the near future

There is another proposed project to construct an under-ground detector of RENO-50 [109] It consists of 5000 tons ofultralow-radioactivity liquid scintillator and photomultipliertubes located at roughly 50 km away from the Yonggwangnuclear power plant in Korea where the neutrino oscillationdue to 120579

12takes place at maximum RENO-50 is expected to

detect neutrinos from nuclear reactors the sun supernovathe earth any possible stellar object and a J-PARC neutrinobeam It could be served as a multipurpose and long-termoperational detector including a neutrino telescopeThemaingoal is to measure the most accurate (1) value of 120579

12and to

attempt determination of the neutrino mass hierarchy

92 Precision Measurement of Mixing Parameters A 20 ktliquid scintillator can have a long list of physics goalsIn addition to neutrino mass hierarchy neutrino mixingparameters including 120579

12 Δ119898212

and Δ119898223

can be measuredat the ideal baseline of 60 km to a precision better than 1Combined with results from other experiments for 120579

23and

12057913 the unitarity of the neutrino mixing matrix can be tested

up to 1 level much better than that in the quark sector forthe CKMmatrixThis is very important to explore the physicsbeyond the standard model and issues like sterile neutrinoscan be studied

In fact for this purpose there is no need to requireextremely good energy resolution and huge detectors Someof the current members of the RENO group indeed proposeda 5 kt liquid scintillator detector exactly for this purpose [109]


If funding is approved they can start right away based on theexisting technology

93 Others A large liquid scintillator detector is also ideal forsupernova neutrinos since it can determine neutrino energiesfor different flavors much better than flavor-blind detectorsGeoneutrinos can be another interesting topic together withother traditional topics such as atmospheric neutrinos solarneutrinos and exotic searches

10 Conclusions and Outlook

Three reactor experiments have definitively measured thevalue of sin22120579

13based on the disappearance of electron

antineutrinos Based on unprecedentedly copious data DayaBay and RENO have performed rather precise measurementsof the value Averaging the results of the three reactorexperiments with the standard Particle Data Group methodone obtains sin22120579

13= 0098 plusmn 0013 [110] It took 14 years

to measure all three mixing angles after the discovery ofneutrino oscillation in 1998

The exciting result of solving the longstanding secretprovides a comprehensive picture of neutrino transformationamong three kinds of neutrinos and opens the possibilityof searching for CP violation in the lepton sector Thesurprisingly large value of 120579

13will strongly promote the

next round of neutrino experiments to find CP violationeffects and determine the neutrino mass hierarchy Therelatively large value has already triggered reconsiderationof future long-baseline neutrino oscillation experimentsThesuccessful measurement of 120579

13has made the very first step

on the long journey to the complete understanding of thefundamental nature and implications of neutrino masses andmixing parameters

References

[1] W Pauli Jr Address to Group on Radioactivity (Tuebingen1930) (Unpublished) Septieme conseil de physique SolvayBruxelles 1033 (Gautier-Villars Paris France 1934)

[2] E Fermi ldquoVersuch einer theorie der 120573-strahlen Irdquo Zeitschriftfur Physik vol 88 no 3-4 pp 161ndash177 1934

[3] F Reines and C L Cowan Jr ldquoDetection of the free neutrinordquoPhysical Review vol 92 no 3 pp 830ndash831 1953

[4] C L Cowan Jr F Reines F B Harrison H W Kruse and AD McGuire ldquoDetection of the free neutrino a confirmationrdquoScience vol 124 no 3212 pp 103ndash104 1956

[5] F Reines C L Cowan Jr F B Harrison A D McGuire and HW Kruse ldquoDetection of the free antineutrinordquo Physical Reviewvol 117 no 1 pp 159ndash173 1960

[6] F Reines and C L Cowan Jr ldquoFree antineutrino absorptioncross section I Measurement of the free antineutrino absorp-tion cross section by protonsrdquo Physical Review vol 113 no 1 pp273ndash279 1959

[7] H Kwon F Boehm A A Hahn et al ldquoSearch for neutrinooscillations at a fission reactorrdquo Physical Review D vol 24 no5 pp 1097ndash1111 1981

[8] Y Declais R Aleksanb M Avenier et al ldquoSearch for neutrinooscillations at 15 40 and 95meters from a nuclear power reactorat Bugeyrdquo Nuclear Physics B vol 434 no 3 pp 503ndash532 1995

[9] G Zacek F V Feilitzsch R L Mossbauer et al ldquoNeutrino-oscillation experiments at the Gosgen nuclear power reactorrdquoPhysical Review D vol 34 no 9 pp 2621ndash2636 1986

[10] Y Declais H de Kerret B Lefievre et al ldquoStudy of reactorantineutrino interaction with proton at Bugey nuclear powerplantrdquo Physics Letters B vol 338 no 2-3 pp 383ndash389 1994

[11] A Afonin et al JETP Letters vol 93 p 1 1988[12] G S Vidyakin V N Vyrodov Yu V Kozlov et al ldquoLimitations

on the characteristics of neutrino oscillationsrdquo JETP Letters vol59 pp 390ndash393 1994

[13] G Vidyakin et al JETP Letters vol 93 p 424 1987[14] G Vidyakin et al JETP Letters vol 59 p 390 1994[15] Z Greenwood W R Kropp M A Mandelkern et al ldquoResults

of a two-position reactor neutrino-oscillation experimentrdquoPhysical Review D vol 53 no 11 pp 6054ndash6064 1996

[16] F Ardellier I Barabanov J C Barriere et al ldquoDoublechooz a search for the neutrino mixing angle theta-13rdquohttparxivorgabshepex060602

[17] X Guo N Wang R Wang et al ldquoA precision measurement ofthe neutrino mixing angle theta-13 using reactor Antineutrinosat Daya Bayrdquo httparxivorgabshep-ex0701029

[18] J Ahn and Reno Collaboration ldquoRENO an experiment forneutrino oscillation parameter theta-13 using reactor neutrinosat Yonggwangrdquo httparxivorgabs10031391

[19] K Schreckenbach G Colvin W Gelletly and F von FeilitzschldquoDetermination of the antineutrino spectrum from 235U ther-mal neutron fission products up to 95 MeVrdquo Physics Letters Bvol 160 no 4-5 pp 325ndash330 1985

[20] F von Feilitzsch A A Hahn and K Schreckenbach ldquoExper-imental beta-spectra from 239Pu and 235U thermal neutronfission products and their correlated antineutrino spectrardquoPhysics Letters B vol 118 no 1ndash3 pp 162ndash166 1982

[21] A Hahn K Schreckenbach W Gelletly F von Feilitzsch GColvin and B Krusche ldquoAntineutrino spectra from 241Pu and239Pu thermal neutron fission productsrdquo Physics Letters B vol218 no 3 pp 365ndash368 1989

[22] ThMueller D Lhuillier M Fallot et al ldquoImproved predictionsof reactor antineutrino spectrardquo Physical Review C vol 83 no5 Article ID 054615 17 pages 2011

[23] WMampe K Schreckenbach P Jeuch et al ldquoThe double focus-ing iron-core electron-spectrometer ldquoBILLrdquo for high resolution(n eminus) measurements at the high flux reactor in GrenoblerdquoNuclear Instruments and Methods vol 154 no 1 pp 127ndash1491978

[24] A Sirlin ldquoGeneral properties of the electromagnetic correctionsto the beta decay of a physical nucleonrdquo Physical Review vol164 no 5 pp 1767ndash1775 1967

[25] P Vogel ldquoAnalysis of the antineutrino capture on protonsrdquoPhysical Review D vol 29 no 9 pp 1918ndash1922 1984

[26] J Hardy B Jonson and P G Hansen ldquoA comment on Pande-moniumrdquo Physics Letters B vol 136 no 5-6 pp 331ndash333 1984

[27] httpwwwnndcbnlgovensdf[28] O Tengblad K Aleklett R von Dincklage E Lund G Nyman

and G Rudstam ldquoIntegral gn-spectra derived from experimen-tal 120573-spectra of individual fission productsrdquo Nuclear Physics Avol 503 no 1 pp 136ndash160 1989


[29] R Greenwood R G Helmer M A Lee et al ldquoTotal absorptiongamma-ray spectrometer formeasurement of beta-decay inten-sity distributions for fission product radionuclidesrdquo NuclearInstruments and Methods in Physics Research A vol 314 no 3pp 514ndash540 1992

[30] O Meplan in Proceeding of the European Nuclear ConferenceNuclear Power for the 21st Century From Basic Research to High-Tech Industry Versailles France 2005

[31] P Vogel ldquoConversion of electron spectrum associated withfission into the antineutrino spectrumrdquo Physical Review C vol76 no 2 Article ID 025504 5 pages 2007

[32] P Huber ldquoDetermination of antineutrino spectra from nuclearreactorsrdquo Physical Review C vol 84 no 2 Article ID 024617 16pages 2011 Erratum-ibid vol 85 Article ID 029901 2012

[33] D LhuillierRecent re-evaluation of reactor neutrino fluxes slidesof a talk given at Sterile Neutrinos at the Crossroads BlacksburgVa USA 2011

[34] N H Haag private communication 2004[35] J Katakura et al ldquoJENDL Fission Product Decay Data Filerdquo

2000[36] K Takahashi ldquoGross theory of first forbidden 120573-decayrdquo Progress

of Theoretical Physics vol 45 no 5 pp 1466ndash1492 1971[37] P Vogel G K Schenter F M Mann and R E Schenter ldquoReac-

tor antineutrino spectra and their application to antineutrino-induced reactions IIrdquoPhysical ReviewC vol 24 no 4 pp 1543ndash1553 1981

[38] B Pontecorvo ldquoInverse beta processes and nonconservation oflepton chargerdquo Zhurnal Eksperimentalnoi i Teoreticheskoi Fizikivol 34 p 247 1958

[39] B Pontecorvo ldquoInverse beta processes and nonconservation oflepton chargerdquo Soviet Physics JETP vol 7 pp 172ndash173 1958

[40] Z Maki M Nakagawa and S Sakata ldquoRemarks on the unifiedmodel of elementary particlesrdquo Progress of Theoretical Physicsvol 28 no 5 pp 870ndash880 1962

[41] M Apollonio A Baldinib C Bemporad et al ldquoLimits on neu-trino oscillations from the CHOOZ experimentrdquo Physics LettersB vol 466 no 2ndash4 pp 415ndash430 1999

[42] M Apollonio A Baldini C Bemporad et al ldquoSearch for neu-trino oscillations on a long base-line at the CHOOZ nuclearpower stationrdquoTheEuropean Physical Journal C vol 27 pp 331ndash374 2003

[43] AGando Y Gando K Ichimura et al ldquoConstraints on 12057913from

a three-flavor oscillation analysis of reactor antineutrinos atKamLANDrdquoPhysical ReviewD vol 83 no 5 Article ID 05200211 pages 2011

[44] PAdamsonCAndreopoulosD J Auty et al ldquoNew constraintsonmuon-neutrino to electron-neutrino transitions inMINOSrdquoPhysical Review D vol 82 Article ID 051102 6 pages 2010

[45] K Abe N Abgrall Y Ajima et al ldquoIndication of electronneutrino appearance from an accelerator-produced off-axisMuon neutrino beamrdquo Physical Review Letters vol 107 no 4Article ID 041801 8 pages 2011

[46] P Adamson D J Auty D S Ayres et al ldquoImproved search forMuon-neutrino to electron-neutrino oscillations in MINOSrdquoPhysical Review Letters vol 107 no 18 Article ID 181802 6pages 2011

[47] Y Abe C Aberle T Akiri et al ldquoIndication of reactor 119907119890

disappearance in the double chooz experimentrdquoPhysical ReviewLetters vol 108 no 13 Article ID 131801 7 pages 2012

[48] Y Abe C Aberle J C dos Anjos et al ldquoReactor electronantineutrino disappearance in the Double Chooz experimentrdquo

Physical Review D vol 86 no 5 Article ID 052008 21 pages2012

[49] G L Fogli E Lisi A Marrone A Palazzo and A M RotunnoldquoEvidence of 120579

13gt 0 from global neutrino data analysisrdquo

Physical ReviewD vol 84 no 5 Article ID 053007 7 pages 2011[50] T Schwetz M Tortola and J W F Valle ldquoWhere we are on 120579

13

addendum to lsquoGlobal neutrino data and recent reactor fluxesstatus of three-flavor oscillation parametersrsquordquo New Journal ofPhysics vol 13 Article ID 109401 5 pages 2011

[51] F P An J Z Bai A B Balantekin et al ldquoObservation ofelectron-antineutrino disappearance at daya bayrdquo PhysicalReview Letters vol 108 Article ID 171803 7 pages 2012

[52] J K Ahn S Chebotaryov J H Choi et al ldquoObservationof reactor electron antineutrinos disappearance in the RENOexperimentrdquo Physical Review Letters vol 108 no 19 Article ID191802 6 pages 2012

[53] F P An and Daya Bay Collaboration ldquoImproved measurementof electron antineutrino disappearance at Daya BayrdquoChin PhysC 37(2013) 011001

[54] F P An Q Anb J Z Bai et al ldquoA side-by-side comparisonof Daya Bay antineutrino detectorsrdquo Nuclear Instruments andMethods in Physics Research A vol 685 pp 78ndash97 2012

[55] httpwwwcgnpccomcnn1093n463576n463598[56] Y YDing Z Y Zhang P J Zhou J C Liu ZMWang andY L

Zhao ldquoResearch and development of gadolinium loaded liquidscintillator for Daya Bay neutrino experimentrdquo Journal of RareEarths vol 25 pp 310ndash313 2007

[57] Y Y Ding Z Zhang J Liu Z Wang P Zhou and Y Zhao ldquoAnew gadolinium-loaded liquid scintillator for reactor neutrinodetectionrdquoNuclear Instruments andMethods in Physics ResearchA vol 584 no 1 pp 238ndash243 2008

[58] M Yeh A Garnov and R L Hahn ldquoGadolinium-loaded liquidscintillator for high-precision measurements of antineutrinooscillations and the mixing angle 120579

13rdquoNuclear Instruments and

Methods in Physics Research A vol 578 no 1 pp 329ndash339 2007[59] Q Zhang Y Wang J Zhang et al ldquoAn underground cosmic-

ray detector made of RPCrdquo Nuclear Instruments and Methodsin Physics Research A vol 583 no 2-3 pp 278ndash284 2007Erratum-ibid A vol 586 p 374 2008

[60] httpgeant4cernch[61] L J Wen J Cao K-B Luk Y Ma YWang and C Yang ldquoMea-

suring cosmogenic 9Li background in a reactor neutrino exper-imentrdquoNuclear Instruments and Methods in Physics Research Avol 564 no 1 pp 471ndash474 2006

[62] T Nakagawa K Shibata S Chiba et al ldquoJapanese evaluatednuclear data library version 3 revision-2 JENDL-32rdquo Journalof Nuclear Science and Technology vol 32 no 12 pp 1259ndash12711995

[63] J Cao ldquoDetermining reactor neutrino fluxrdquo Nuclear PhysicsBmdashProceedings Supplements In press httparxivorgabs11012266 Proceeding of Neutrino 2010

[64] S F E Tournu et al Tech Rep EPRI 20011001470 Palo AltoCalif USA 2001

[65] C Xu X N Song L M Chen and K Yang Chinese Journal ofNuclear Science and Engineering vol 23 p 26 2003

[66] S Rauck ldquoSCIENCE V2 nuclear code packagemdashqualificationreport (Rev A)rdquo Framatome ANP Document NFPSDDC8914 2004

[67] R Sanchez I Zmijarevi M Coste-Delclaux et al ldquoAPOLLO2YEAR 2010rdquoNuclear Engineering and Technology vol 42 no 5pp 474ndash499 2010


[68] R R G Marleau A Hebert and R Roy ldquoA user guide forDRAGONrdquo Tech Rep IGE-236 Rev 1 2001

[69] C E Sanders and I C Gauld ldquoORNL isotopic analysis of high-burnup PWR spent fuel samples from the takahama-3 reactorrdquoTech Rep NUREGCR-6798ORNLTM-2001259 2002

[70] Z Djurcic J A Detwiler A Piepke V R Foster L Millerand G Gratta ldquoUncertainties in the anti-neutrino productionat nuclear reactorsrdquo Journal of Physics G vol 36 no 4 ArticleID 045002 2009

[71] P Vogel and J F Beacom ldquoAngular distribution of neutroninverse beta decay 119907

119890+ 119890++ 119899rdquo Physical Review D vol 60 no

5 Article ID 053003 10 pages 1999[72] V I Kopeikin L A Mikaelyan and V V Sinev ldquoReactor as

a source of antineutrinos thermal fission energyrdquo Physics ofAtomic Nuclei vol 67 no 10 pp 1892ndash1899 2004

[73] F P An G Jie Z Xiong-Wei and L Da-Zhang ldquoSimulationstudy of electron injection into plasma wake fields by collidinglaser pulses using OOPICrdquoChinese Physics C vol 33 article 7112009

[74] B Zhou R Xi-Chao N Yang-Bo Z Zu-Ying A Feng-Pengand C Jun ldquoA study of antineutrino spectra from spent nuclearfuel at Daya Bayrdquo Chinese Physics C vol 36 no 1 article 0012012

[75] D Stump J Pumplin R Brock et al ldquoUncertainties of pre-dictions from parton distribution functions I The Lagrangemultiplier methodrdquo Physical Review D vol 65 no 1 Article ID014012 17 pages 2001

[76] NEA-184501 documentation for MURE 2009[77] G Marleau et al Tech Rep IGE-157 1994[78] C Jones Prediction of the reactor antineutrino flux for the double

chooz experiment [PhD thesis] MIT Cambridge Mass USA2012

[79] C Jones A Bernstein J M Conrad et al ldquoReactor simulationfor antineutrino experiments using DRAGON and MURErdquohttparxivorgabs11095379

[80] A Pichlmaier V Varlamovb K Schreckenbach and P Gel-tenbort ldquoNeutron lifetimemeasurement with theUCN trap-in-trap MAMBO IIrdquo Physics Letters B vol 693 no 3 pp 221ndash2262010

[81] J Allison KAmako J Apostolakis et al ldquoGeant4 developmentsand applicationsrdquo IEEE Transactions on Nuclear Science vol 53no 1 pp 270ndash278 2006

[82] J S Agostinelli J Allison K Amako et al ldquoGeant4mdasha sim-ulation toolkitrdquo Nuclear Instruments and Methods in PhysicsResearch A vol 506 no 3 pp 250ndash303 2003

[83] D R Tilley J H Kelley J L Godwin et al ldquoEnergy levels oflight nuclei A = 8910rdquo Nuclear Physics A vol 745 no 3-4 pp155ndash362 2004

[84] Y Prezado M J G Borge C A Diget et al ldquoLow-lyingresonance states in the 9Be continuumrdquo Physics Letters B vol618 no 1ndash4 pp 43ndash50 2005

[85] P Papka T A D Brown B R Fulton et al ldquoDecay pathmeasurements for the 2429 MeV state in 9Be implications forthe astrophysical 120572+120572+n reactionrdquo Physical Review C vol 75no 4 Article ID 045803 8 pages 2007

[86] httpwwwchemagilentcomen-USProductsinstru-mentsmolecularspectroscopyuorescencesystemscaryeclipsepagesdefaultaspx

[87] C Aberle C Buck B Gramlich et al ldquoLarge scale Gd-beta-diketonate based organic liquid scintillator production for anti-neutrino detectionrdquo Journal of Instrumentation vol 7 ArticleID P06008 2012

[88] C Aberle C Buck F X Hartmann S Schonert and SWagnerldquoLight output of Double Chooz scintillators for low energyelectronsrdquo Journal of Instrumentation vol 6 Article ID P110062011

[89] C Aberle [PhD thesis] Universitat Heidelberg HeidelbergGermany 2011

[90] P Adamson C Andreopoulos R Armstrong et al ldquoMea-surement of the neutrino mass splitting and flavor mixing byMINOSrdquo Physical Review Letters vol 106 no 18 Article ID181801 6 pages 2011

[91] H Nunokawa S Parke and R Z Funchal ldquoAnother possibleway to determine the neutrino mass hierarchyrdquo Physical ReviewD vol 72 no 1 Article ID 013009 6 pages 2005

[92] G Feldman and R Cousins ldquoUnified approach to the classicalstatistical analysis of small signalsrdquo Physical Review D vol 57no 7 pp 3873ndash3889 1998

[93] G Mention M Fechner Th Lasserre et al ldquoReactor antineu-trino anomalyrdquo Physical Review D vol 83 no 7 Article ID073006 20 pages 2011

[94] A Hoummada and S Lazrak Mikou ldquoNeutrino oscillationsILL experiment reanalysisrdquo Applied Radiation and Isotopesvol 46 no 6-7 pp 449ndash450 1995

[95] P Anselmann R Fockenbrocka W Hampel et al ldquoFirst resultsfrom the 51Cr neutrino source experiment with the GALLEXdetectorrdquo Physics Letters B vol 342 no 1ndash4 pp 440ndash450 1995

[96] W Hampel G Heussera J Kiko et al ldquoFinal results of the 51Crneutrino source experiments inGALLEXrdquoPhysics Letters B vol420 no 1-2 pp 114ndash126 1998

[97] F Kaether W Hampel G Heusser J Kiko and T KirstenldquoReanalysis of the Gallex solar neutrino flux and source exper-imentsrdquo Physics Letters B vol 685 no 2 pp 47ndash54 2010

[98] D Abdurashitov V N Gavrin S V Girin et al ldquoThe Russian-American gallium experiment (SAGE) Cr neutrino sourcemeasurementrdquo Physical Review Letters vol 77 no 23 pp 4708ndash4711 1996

[99] D Abdurashitov V N Gavrin S V Girin et al ldquoMeasurementof the response of a Ga solar neutrino experiment to neutrinosfrom a 37Ar sourcerdquo Physical Review C vol 73 no 4 Article ID045805 12 pages 2006

[100] D Abdurashitov V N Gavrin V V Gorbachev et al ldquoMeasure-ment of the solar neutrino capture rate with gallium metal IIIResults for the 2002ndash2007 data-taking periodrdquo Physical ReviewC vol 80 no 1 Article ID 015807 16 pages 2009

[101] C Giunti and M Laveder ldquoShort-baseline electron neutrinodisappearance tritiumbeta decay and neutrinoless double-betadecayrdquo Physical Review D vol 82 no 5 Article ID 053005 14pages 2010

[102] A Bernstein in Proceedings of Neutrinos and Arm ControlWorkshop Honolulu Hawaii USA 2003

[103] A Porta et al ldquoReactor neutrino detection for non proliferationwith the Nucifer experimentrdquo Journal of Physics ConferenceSeries vol 203 no 1 Article ID 012092 2010

[104] S T Petcov and M Piai ldquoThe LMA MSW solution of thesolar neutrino problem inverted neutrino mass hierarchy andreactor neutrino experimentsrdquoPhysics Letters B vol 533 no 1-2pp 94ndash106 2002

[105] S Choubey S T Petcov and M Piai ldquoPrecision neutrino oscil-lation physics with an intermediate baseline reactor neutrinoexperimentrdquoPhysical ReviewD vol 68 no 11 Article ID 11300619 pages 2003


[106] J Learned S T Dye S Pakvasa and R C Svoboda ldquoDeter-mination of neutrino mass hierarchy and 120579

13with a remote

detector of reactor antineutrinosrdquo Physical Review D vol 78no 7 Article ID 071302 5 pages 2008

[107] L Zhan Y Wang J Cao and L Wen ldquoDetermination of theneutrino mass hierarchy at an intermediate baselinerdquo PhysicalReview D vol 78 no 11 Article ID 111103 5 pages 2008

[108] L Zhan Y Wang J Cao and L Wen ldquoExperimental require-ments to determine the neutrino mass hierarchy using reactorneutrinosrdquo Physical Review D vol 79 no 7 Article ID 0730075 pages 2009

[109] S B Kim in Talk Given at the Conference of Neutrino 2012[110] J Beringer J-F Arguin R M Barnett et al ldquoReview of particle

physicsrdquoPhysical ReviewD vol 86 no 1 Article ID 010001 1528pages 2012

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


FluidsJournal of

Atomic and Molecular Physics

Journal of



Advances in Condensed Matter Physics

OpticsInternational Journal of



AstronomyAdvances in

International Journal of


Superconductivity


Statistical MechanicsInternational Journal of


GravityJournal of


AstrophysicsJournal of


Physics Research International


Solid State PhysicsJournal of

Computational Methods in Physics

Journal of



Soft MatterJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

AerodynamicsJournal of

Volume 2014


PhotonicsJournal of


Journal of

Biophysics


ThermodynamicsJournal of


products one expects about 2times 1020 ]119904 emitted in a 4120587 solidangle from a 1GW reactor (thermal power) Since unstablefission products are neutron-rich nuclei all 120573 decays are of120573minus type and the neutrino flux is actually pure electronic

antineutrinos (]119890)

The neutrino oscillation search at a reactor is alwaysbased on a disappearance measurement using the powerfulinverse beta decay (IBD) detection process to discriminatethe neutrino signal from backgrounds The observed neu-trino spectrum at a distance 119871 from a reactor is comparedto the expected spectrum If a deficit is measured it canbe interpreted in terms of the disappearance probabilitywhich in the two neutrino mixing approximation reducesto

119875119890119890= 1 minus sin22120579 sin2 (Δ119898

2119871

4119864) (1)

where Δ1198982 is the difference between the squared masses ofthe two neutrino states and 120579 is the mixing angle fixing theamplitude of the oscillation

Here we will especially consider reactor antineutrinodetector at short distances below 100m from the reactor corein particular ILL-Grenoble Goesgen Rovno KrasnoyarskSavannah River and Bugey [7ndash15] These experiments haveplayed an important role in the establishment of neutrinophysics and especially neutrino oscillations over the lastfifty years Unlike modern long-baseline reactor experimentsmotivated by the measurement of the last unknown mixingangle 120579

13[16ndash18] which measure 119875

119890119890by comparing the event

rate and spectrum in two detectors at different distances theaforementioned short baseline experiments can only employone detector and therefore depend on an accurate theoreticalprediction for the emitted ]

119890flux and spectrum to measure

119875119890119890Until late 2010 all data from reactor neutrino experiments

appeared to be fully consistent with the mixing of ]119890 ]120583

and ]120591with three mass eigenstates ]

1 ]2 and ]

3 with

the squared mass differences |Δ119898231| ≃ 24 10

minus3eV2 andΔ1198982

21|Δ1198982

31| ≃ 0032 The measured rate of ]e was found

to be in reasonable agreement with that predicted from theldquooldrdquo reactor antineutrino spectra [19ndash21] though slightlylower than expected with the measuredexpected ratio at0980plusmn0024 including recent revisions of the neutronmeanlifetime 120591

119899= 8815 s in 2011 (PDG)

In preparation for the Double Chooz reactor experiment[16] the Saclay reactor neutrino group reevaluated the spe-cific reactor antineutrino flux for 235U 239Pu 241Pu and 238UIn 2011 they reported their results [22] which correspond to aflux that is a few percent higher than the previous predictionThis also necessitates a reanalysis of the ratio of the observedevent rate to the predicted rate for 19 published experimentsat reactor-detector distances below 100m

21 Reference Antineutrino Spectra Fission reactors releaseabout 1020 ]

119890GWminus1sminus1 which mainly come from the beta

decays of the fission products of 235U 238U 239Pu and241Pu The emitted antineutrino spectrum is then givenby

119878tot (119864]) = sum

119896

119891119896119878119896(119864]) (2)

where 119891119896refers to the contribution of the main fissile

nuclei to the total number of fissions of the kth branchand 119878

119896to their corresponding neutrino spectrum per

fissionThe distribution of the fission products of uranium

or plutonium isotopes covers hundreds of nuclei each ofthem contributing to 119878

119896(119864) through various 120573 decay chains

At the end the total antineutrino spectrum is a sum ofthousands of 120573-branches weighted by the branching ratio ofeach transition and the fission yield of the parent nucleusDespite the impressive amount of data available in nucleardatabases the ab initio calculation of the emitted antineutrinospectrum is difficult Moreover when looking at the detectedspectrum through the IBD process the 1806MeV thresholdand the quadratic energy dependence of the cross-sectionenhance the contribution of transitions with large endpoints(1198640gt 4MeV) Systematic errors of the nuclear data and the

contribution of poorly known nuclei become a real limitationfor the high energy part of the antineutrino spectrumUncertainties below the 10 level seem to be out of reachwiththe ab initio approach preventing any accurate oscillationanalysis

In order to circumvent this issue measurements of total120573 spectra of fissile isotopes were performed in the 1980s atILL [19ndash21] a high flux research reactor in Grenoble FranceThin target foils of fissile isotopes 235U 239Pu and 241Puwere exposed to the intense thermal neutron flux of thereactor A tiny part of the emitted electrons could exit the corethrough a straight vacuum pipe to be detected by the highresolution magnetic spectrometer BILL [23] The electronrates were recorded by a pointwise measurement of thespectrum in magnetic field steps of 50 keV providing anexcellent determination of the shape of the electron spectrumwith subpercent statistical error The published data weresmoothed over 250 keV Except for the highest energy binswith poor statistics the dominant error was the absolutenormalization quoted around 3 (90 CL) with weakenergy dependence

In principle the conversion of a 120573-spectrum into anantineutrino spectrum can be done using the energy conser-vation between the two leptons

119864119890+ 119864] = 1198640 (3)

with 1198640 the endpoint of the 120573 transition However this

approach requires to know the contribution of all singlebranches in the ILL sectra and this information is notaccessible from the integral measurement Therefore a spe-cific conversion procedure was developped using a set of30 ldquovirtualrdquo 120573-branches fitted on the data The theoretical



NormtimesF(119885 119860 119864

119890)⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Fermi function

times 119901119890119864119890(119864119890minus 1198640)2

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Phasespace

times (1 + 120575 (119885 119860 119864119890))⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Correction

(4)




0in


119885 (1198640) = 495 minus 07119864

0minus 009119864

2

0 119885 le 34 (5)





Δ119878branch (119864]) ≃ 065 (119864] minus 400) (6)













119864 (MeV)1 2 3 4 5 6 7 8

minus006

minus004

minus002

0

002

004

006

119885 = 46


(119873tr

ue120584

minus119873

fit 120584)119873

true

120584

(a)

1 2 3 4 5 6 7 8minus006

minus004

minus002

0

002

004

006


(119873tr

ue120584

minus119873

conv

120584)119873

true

120584(b)


0 2 4 6 8 10203040506070

1198640 (MeV)











2 3 4 5 6 7 8

0

005

01

015

119864120584 (MeV)

minus005

(120601minus120601

ILL)120601

ILL

Our result11012663







0 2 4 6 8 10

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

119864120584 (MeV)

1198710

1198710

119866120584

0 2 4 6 8 10

119866120573

119864119890 (MeV)

S

S C

C

120575WM

120575WM




0 C Coulomb


























minus5 eV2










minus008)times



120591candidate


2



32(31)= (232

+012













200 m

EH3

EH1

EH2

AD6 AD4

AD3

AD1 AD2

AD5

L1L2

L3L4

D1D2

Daya Bay NPP

Ling Ao-II NPP

Ling Ao NPP






120583rarr ]e and ]

120583rarr ]e







13that are between





4 Daya Bay










120583(GeV) ADs D1 D2 L1 L2 L3 L4


RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO




119890+ 119901 rarr 119890











Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





NormtimesF(119885 119860 119864

119890)⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Fermi function

times 119901119890119864119890(119864119890minus 1198640)2

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Phasespace

times (1 + 120575 (119885 119860 119864119890))⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

Correction

(4)




0in


119885 (1198640) = 495 minus 07119864

0minus 009119864

2

0 119885 le 34 (5)





Δ119878branch (119864]) ≃ 065 (119864] minus 400) (6)













119864 (MeV)1 2 3 4 5 6 7 8

minus006

minus004

minus002

0

002

004

006

119885 = 46


(119873tr

ue120584

minus119873

fit 120584)119873

true

120584

(a)

1 2 3 4 5 6 7 8minus006

minus004

minus002

0

002

004

006


(119873tr

ue120584

minus119873

conv

120584)119873

true

120584(b)


0 2 4 6 8 10203040506070

1198640 (MeV)











2 3 4 5 6 7 8

0

005

01

015

119864120584 (MeV)

minus005

(120601minus120601

ILL)120601

ILL

Our result11012663







0 2 4 6 8 10

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

119864120584 (MeV)

1198710

1198710

119866120584

0 2 4 6 8 10

119866120573

119864119890 (MeV)

S

S C

C

120575WM

120575WM




0 C Coulomb


























minus5 eV2










minus008)times



120591candidate


2



32(31)= (232

+012













200 m

EH3

EH1

EH2

AD6 AD4

AD3

AD1 AD2

AD5

L1L2

L3L4

D1D2

Daya Bay NPP

Ling Ao-II NPP

Ling Ao NPP






120583rarr ]e and ]

120583rarr ]e







13that are between





4 Daya Bay










120583(GeV) ADs D1 D2 L1 L2 L3 L4


RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO




119890+ 119901 rarr 119890











Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




119864 (MeV)1 2 3 4 5 6 7 8

minus006

minus004

minus002

0

002

004

006

119885 = 46


(119873tr

ue120584

minus119873

fit 120584)119873

true

120584

(a)

1 2 3 4 5 6 7 8minus006

minus004

minus002

0

002

004

006


(119873tr

ue120584

minus119873

conv

120584)119873

true

120584(b)


0 2 4 6 8 10203040506070

1198640 (MeV)











2 3 4 5 6 7 8

0

005

01

015

119864120584 (MeV)

minus005

(120601minus120601

ILL)120601

ILL

Our result11012663







0 2 4 6 8 10

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

119864120584 (MeV)

1198710

1198710

119866120584

0 2 4 6 8 10

119866120573

119864119890 (MeV)

S

S C

C

120575WM

120575WM




0 C Coulomb


























minus5 eV2










minus008)times



120591candidate


2



32(31)= (232

+012













200 m

EH3

EH1

EH2

AD6 AD4

AD3

AD1 AD2

AD5

L1L2

L3L4

D1D2

Daya Bay NPP

Ling Ao-II NPP

Ling Ao NPP






120583rarr ]e and ]

120583rarr ]e







13that are between





4 Daya Bay










120583(GeV) ADs D1 D2 L1 L2 L3 L4


RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO




119890+ 119901 rarr 119890











Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




2 3 4 5 6 7 8

0

005

01

015

119864120584 (MeV)

minus005

(120601minus120601

ILL)120601

ILL

Our result11012663







0 2 4 6 8 10

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

0

5

10

minus10

minus5

Size

of c

orre

ctio

n (

)

119864120584 (MeV)

1198710

1198710

119866120584

0 2 4 6 8 10

119866120573

119864119890 (MeV)

S

S C

C

120575WM

120575WM




0 C Coulomb


























minus5 eV2










minus008)times



120591candidate


2



32(31)= (232

+012













200 m

EH3

EH1

EH2

AD6 AD4

AD3

AD1 AD2

AD5

L1L2

L3L4

D1D2

Daya Bay NPP

Ling Ao-II NPP

Ling Ao NPP






120583rarr ]e and ]

120583rarr ]e







13that are between





4 Daya Bay










120583(GeV) ADs D1 D2 L1 L2 L3 L4


RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO




119890+ 119901 rarr 119890











Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





















minus5 eV2










minus008)times



120591candidate


2



32(31)= (232

+012













200 m

EH3

EH1

EH2

AD6 AD4

AD3

AD1 AD2

AD5

L1L2

L3L4

D1D2

Daya Bay NPP

Ling Ao-II NPP

Ling Ao NPP






120583rarr ]e and ]

120583rarr ]e







13that are between





4 Daya Bay










120583(GeV) ADs D1 D2 L1 L2 L3 L4


RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO




119890+ 119901 rarr 119890











Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








minus5 eV2










minus008)times



120591candidate


2



32(31)= (232

+012













200 m

EH3

EH1

EH2

AD6 AD4

AD3

AD1 AD2

AD5

L1L2

L3L4

D1D2

Daya Bay NPP

Ling Ao-II NPP

Ling Ao NPP






120583rarr ]e and ]

120583rarr ]e







13that are between





4 Daya Bay










120583(GeV) ADs D1 D2 L1 L2 L3 L4


RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO




119890+ 119901 rarr 119890











Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








120583(GeV) ADs D1 D2 L1 L2 L3 L4


RPC

OWS

IWS

Muon PMTs

Tyvek4-m OAV3-m IAV

AD PMTs

AD stand

Reflectors

SSV

Radial shield

ACU-BACU-A ACU-C

20 t Gd-LS20 t LS

37 t MO




119890+ 119901 rarr 119890











Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





Entr

ies

AD1AD2AD3

AD4AD5AD6

1

10minus1

10minus2

10minus3

10minus4

10minus5









AD number

Asy

mm

etry

0

0002

0004

0006

0008

001

IBD n-GdSpa n-Gd


1 2 3 4 5 6

minus0004

minus0002

Asy

mm

etry

0000200040006

minus0004minus0002

minus0006

0 2 4 6 8 10

68Ge60CoAm-C n-Gd

215Po 120572214Po 120572212Po 120572






Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




Prompt energy (MeV)

0

200

400

600

800

1000

1200

1400

Data EH1-AD1MC

0

500

1000

1500

2000

0 02 04 06 08 1 12 14 16 18

Entr

ies

01 M

eV

0 2 4 6 8 10 12






119889minus 119905119901lt 200 120583s where 119905

119901



119889minus 119905120583W119878

lt



119889minus 119905120583sh


119889lt 120MeV







0

1000

2000

3000

4000

5000

6000

7000

Data EH1-AD1MC

5 6 7 8 9 10 11 12

Entr

ies

01 M

eV




1

10

Data EH1-AD1MC

0200400600800

1000

0 50 100 150 200 250 300Time interval (120583s)

0 5 10 15 20 25 30

Entr

ies120583

s

102

103

Entr

ies5120583

s




backgrounds




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




























0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics












0

5000

10000

AD1AD2

Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

AD

1A

D2

08

09

1

11

12



(b)





119894) [19ndash


119878 (119864) =119882th

sum119896119891119896119864119896

sum

119894

119891119894119878119894(119864) (7)






119894=



D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




D ra

te (

day)

400

600

800

EH1

Measured

D1 off

IBD

rate

(da

y)

400

600

800EH2

L2 on

L1 off

L1 on L4 off

Run time

IBD

rate

(da

y)

40

60

80

100 EH3












119877 =119872119891

119873119891

=119872119891

120572119872119886+ 120573119872

119887

(8)




where 119873119891and 119872



119887are the






1205942=

6

sum

119889=1

[119872119889minus 119879119889(1 + 120576 + sum

119903120596119889

119903120572119903+ 120576119889) + 120578119889]2

119872119889+ 119861119889

+sum

119903

1205722

119903

1205902119903

+

6

sum

119889=1

(1205762

119889

1205902119889

+1205782

119889

1205902119861

)

(10)







119903(08) as shown in Table 5 120590

119889(02) is the



119903 120576119889 and 120578





31

119871

119864)

minus cos412057913sin22120579

12sin2 (1267Δ1198982

21

119871

119864)

(11)

where Δ119898231


12= 0861

+0026

minus0022 and

Δ1198982

21= 759

+020


2

31had





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





09

095

1

105

11

115

EH3

EH1 EH2

010203040506070

0 02 04 06 08 1 12 14 16 18 2

119873de

tect

ed119873

expe

cted

1205942

1120590

5120590

3120590

0 005 01 015sin2212057913








13obtained


5 Double Chooz


0

500

1000

1500

2000


Prompt energy (MeV)

Entr

ies

025

MeV

0 5 10

(a)

Far

near

(wei

ghte

d)

08

1

12



(b)






Glove box (GB)

Gamma catcher (GC)

Buffer (B)

Outer veto (OV)

Inner veto (IV)

Steel shielding

Upper OV


Acrylic vessels

120584-target (NT)

7 m

7 m




119877



119896


⟨119864119891⟩119877= sum

119896

120572119896⟨119864119891⟩119896 (13)





119896










119878119896(119864)120590IBD(119864

true] ) No 02

⟨119864119891⟩ No 02

119871119877

Yes lt01120572119877

119896No 09

Total 18



⟨120590119891⟩119877= ⟨120590119891⟩Bugey

+sum

119896

(120572119877

119896minus 120572

Bugey119896

) ⟨120590119891⟩119896 (14)




119873exp119877119894

=120598119873119901

4120587

1

119871119877

2

119875119877

th⟨119864119891⟩119877

times (⟨120590119891⟩119877

(sum119896120572119877119896⟨120590119891⟩119896)sum

119896

120572119877

119896⟨120590119891⟩119894

119896)

(15)










119894119895=

120575119873exp119894120575119873

exp119895















119864vis = 119875119864119898(120588 119911 119905) times 119891

119898

119906(120588 119911) times 119891

119898

119904(119905) times 119891

119898

MeV (16)





119894) from the


⨀= 119875119864119898(120588 119911) times 119891

119898



119906(120588 119911) Independent




119898






response at 1199050 as119875119864119898

⨀1199050= 119875119864119898

⨀(119905)times119891

119898

119904(119905)The 119905

0was defined


Thenumber119875119864⨀1199050




⨀1199050MeV

and 2277119875119864⨀1199050















120583gt






120583] equiv








(2) In the 119864vis120583






120583above 275MeV

(3) The cut 119864vis120583







119890events The











119890events




0

10

20

30

40

50

DataNo oscillation


Obs

erve

d ra

te (d

ayminus1)













119894


119873119901red119894=

Reactorssum

119877=12

119873]119877119894

+

Bkgnds

sum

119887

119873119887

119894 (17)

where 119873]119877119894

= 119875(]119890rarr ]119890)119873

exp119877119894






119894119895in order to


119872119894119895= 119872

sig119894119895

+119872det 119894119895

+119872stat119894119895

+119872eff119894119895

+

Bkgnds

sum

119887

119872119887

119894119895 (18)

Each term 119872119860

119894119895= cov(119873pred

119894 119873

pred119895



and119873pred119895








1205942=

36

sum

119894119895

(119873119894minus 119873

pred119894

) times (119872119894119895)minus1

(119873119895minus 119873

pred119895

)119879


2

1205902FNSM+(120598 9Li minus 1)

2

12059029Li+(120572119864minus 1)2

1205902120572119864

+

(Δ1198982

31minus (Δ119898

2

31)MINOS

)2

1205902MINOS

(19)









13= 0109 plusmn





2 4 6 8 10 12

2 4 6 8 10 12

Energy (MeV)

Energy (MeV)2 4 6 8 10 12

Energy (MeV)

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

100

200

300

400

500

600

700

800

900

1000

Both reactors on

Even

ts0

5 MeV

Even

ts0

5 MeV

05

1015

Even

ts0

5 MeV

05

1015

20

(Dat

apr

edic

ted)

(Dat

apr

edic

ted)

(05

MeV

)


31 = 000232 eV2




(1205942dof = 42135)


13= 0109 and Δ1198982

31= 232 times 10






1000 plusmn 0011 0986 plusmn 0007Δ1198982





13= 0170 plusmn 0052 at





13le 025 A Δ120594






6 RENO




at Δ119898231 = 000232 eV2


2 4 6 8 10 12Energy (MeV)

Even

ts0

5 MeV

0102030

2 4 6 8 10 12Energy (MeV)

minus100

minus50

050

0608

11214

200

400

600

800

1000

1200

1400Ev

ents

05 M

eV(D

ata

pred

icte

d)(D

ata

pred

icte

d)(0

5 M

eV)

(1205942dof = 42135)







13with two









119890+ 119901 rarr 119890
























119890yield






D ra

te (

day)

700800900

Near detectorR2 off

R2 on R1 off

IBD

rate

(da

y)

50

100Far detector

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012

Run time

Aug 29 Oct 28 Dec 27 Feb 252011 2012











0

500

1000


Prompt energy (MeV)

00

10

5 10


20

30

40

Entr

ies

025

MeV

Entr

ies

025

MeV


(a)


Far

near

08

1

12

(b)



13= 0113 plusmn


















119890+1H rarr 119890




119873Pred] (119904

minus1) =

1

41205871198712119873119901

119875th

⟨119864119891⟩120590pred119891

(22)





⟨119864119891⟩ = sum

119896

⟨119864119896⟩ 119896 =

235U238U239Pu241Pu (23)


120590pred119891

= int

infin

0

119878tot (119864]) 120590VminusA (119864]) 119889119864] = sum

119896

119891119896120590pred119891119896

(24)

where the 120590pred119891119896




120590VminusA (119864119890) [cm2] =

857 times 10minus43

120591119899 [s]

119901119890 [MeV]


(25)





119891119896 is shifted










Bugey-4 3He + H2O 8887 0538 0328 0078 0056 0987 0926 30 30 15

ROVNO91 3He + H2O 8886 0614 0274 0074 0038 0985 0924 39 30 18



Buge

y-4 RO

VN

O91

Buge

y-3

Buge

y-3

Buge

y-3

Goe

sgen

-I

Goe

sgen

-II

Goe

sgen

-III

ILL

Kras

noya

rsk-

I

Kras

noya

rsk-

II

Kras

noya

rsk-

III

SRP-

ISR

P-II

ROV

NO

88-1

IRO

VN

O88

-2I

ROV

NO

88-1

S

ROV

NO

88-2

S

ROV

NO

88-3

S

Palo

Ver

de

CHO

OZ

Dou

ble C

HO

OZ

07508

08509

0951

10511

115

Nucifer(2012)

119873O

BS(119873

exp) p

red

new

100 101 102 103












ano2012119891

=




2

min lt

1205942












119875119890119890= 1 minus sin2 (2120579new) sin

2(Δ1198982

new119871

4119864]119890

) (26)


sin2 (2120579new) = 410038161003816100381610038161198801198904

10038161003816100381610038162

(1 minus10038161003816100381610038161198801198904

10038161003816100381610038162

) (27)


(119875119890119890minus )119879

119882minus1(119875119890119890minus ) (28)








2468

2468

2468

2468

10

10

5

5

102

101

100

100

10minus1


10minus2

Δ1205942

Δ1205942

Δ1198982 ne

w(e

V2)

2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

lowast

(a)

lowast

2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )


1 do

fΔ1205942

profi

le


909599

(b)







star


2





|Δ1198982



2


2


23 plusmn 01 eV2


2





2468

2468

2468

2468

10

5

102

101

100

10minus1

10minus2

Δ1205942

Δ1198982 ne

w(e

V2)


2 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8

sin2(2120579new )



1 do

fΔ1205942

profi

le

909599

lowast




2




119890












9 Future Prospects










FCT (120596) = int119905max

119905min

119865 (119905) cos (120596119905) d119905

FST (120596) = int119905max

119905min

119865 (119905) sin (120596119905) d119905(29)


23[107]













12and to



12 Δ119898212

and Δ119898223


23and


















References























































13































































13with a remote











FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Documents

Review Article Reactor Neutrinosdownloads.hindawi.com/journals/ahep/2013/453816.pdfMiddle and long-baseline oscillation experiments at Daya Bay, Double Chooz, and RENO provided very