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Double Chooz Near Detector. Guillaume MENTION CEA Saclay, DAPNIA/SPP Workshop AAP 2007 Friday, December 14 th , 2007. http://doublechooz.in2p3.fr/. Double Chooz detector capabilities. Double Chooz experiment The site The 2 identical detectors - PowerPoint PPT Presentation
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Double Chooz Double Chooz Near DetectorNear Detector
Guillaume MENTION
CEA Saclay, DAPNIA/SPP
Workshop AAP 2007Friday, December 14th, 2007
http://doublechooz.in2p3.fr/
Double ChoozDouble Choozdetector capabilities detector capabilities
- Double Chooz experiment- The site- The 2 identical detectors- The reactors: powerful anti-neutrino sources
- Expected performance- Detection of reactor anti-neutrinos: e+ and neutron- Anti-neutrino spectrum measurement (Far and Near detectors)- Thermal power measurement- Burn-up detection
-Conclusions
Chooz power plant mapChooz power plant map
Near site: D~380 m, overburden 120 mwe Far site: D~1.05 km, overburden 300 mwe
Type PWR (N4)
# Cores 2
Th. Power 8.5 GWth
Operating since 1996/1997
Load Factor 78%
The experiment siteThe experiment site
ν ν ννννν
ν1051 m380 m
Double Chooz: 2 phasesDouble Chooz: 2 phases
Double Chooz phase 1: far detector only may help to reach a higher precision on anti-e spectrum…
Double Chooz phase 2: higher precision on anti- e spectrum~ 2 105 events in 3 years
Timeline
Site Proposal Construction FarDesign
2004 2005 2006 2007 2008 2009 2010 2011 2012Data Taking (Phase I)
Cstr. Near Data Taking (Phase II)
Reactors are abundant Reactors are abundant antineutrino sourcesantineutrino sources
235U239Pu
Days
235U
239Pu
238U 241PuF
issi
on
per
cen
tag
es
235U 239Pu
Energy released per fission
201.7 MeV 210.0 MeV
Average energy of e 2.94 MeV 2.84 MeV
# e per fission > 1.8 MeV 1.92 1.45
More than 1021 fissions/second
νe identification: using coïncidences (allows strongly reducing backgrounds)
(1) 0,5 < Eprompt < 10 MeV
(2) 6 < Edelayed < 10 MeV
(3) 1 μs < Δt < 100 μs
―
Σ ≃ 8 MeV
Ee+
+ 1 MeV
Δt < 100 μs
te+ n
ννee Detection technique Detection technique
50 years of Physics50 years of Physics
Detector structureDetector structure
Far detector
Double Chooz: 2 identical detectors
CalibrationGlove-Box
Outer Veto:plastic scintillator panels
-Target: 10.3 m3 liquid scintillator doped with 0.1% of Gd
γ-Catcher:22.6 m3 liquid scintillator
Buffer: 114 m3 mineral oilwith ~400 PMTs
Inner Veto: 90 m3 liquid scintillatorwith 80 PMTs
Shielding: 15 cm steel
4 LiquidVolumes
9
BackgroundsBackgroundsfast neutrons
Gdγ ~ 8 MeV
proton recoils
μ → (9Li, 8He) → β-n
γPM + rocks
+ neutron-lik
e event
Acc
iden
tals
~~~~~
~~~~~~
~~
~ ~ ~
~~~~
Cor
rela
ted
(CHOOZ data)
Far detector capabilitiesFar detector capabilities
• Far site: phase I of Double Chooz• Anti-neutrino spectrum measurement over 1.5 years. (~ 22 000 anti-neutrinos):
– Require the knowledge of the average power over 1.5 years– Require the knowledge of the average fuel composition over 1.5 years
• Would allow to measure the antineutrino rate at a statistical precision of 0.7%(in case of no systematics)
• But also the shape of the spectrum,with a statistical precision of 2 to 3%per energy bin (with 8 bins between1.5 and 5.5 MeV).
• Systematical uncertainties reduce thispotential which is limited by the knowledgeon the detector normalization (~ 2%) andon the reactor powers (~ 2%).
• Backgrounds also lead to some systematicalsubtraction error around 1% per energy bin
• The measured spectrum will include the oscillationeffect.
Evis in MeV
# an
ti- e
in 1
.5 y
ears stat
stat”+” syst
Map of the near siteMap of the near site(Preliminary, still under study)(Preliminary, still under study)
• Distance to reactor cores: 456 m & 340 m 385 m (1 R. with 2Pth)
• Neutrino fluxes: w/o eff. 496 anti-e/day
2.5 105 events in 3 years (all eff. included)• Depth: 120 m.w.e. ( flux: ~ 3-4 /m-2s-1)
456 m
340
m
160 m
Cho
oz N
PP
, m
ass
map Near site
location
Accesstunnel
Huber &
Schw
etz hep-ph/040702
6Thermal power measurementThermal power measurement
with the near detectorwith the near detector
1 error on thermalpower
measurement
~ 10 000 events/month@ Double Chooz Near
• Thermal power is measured at ~2% (?) by the nuclear power companies• Current measurement at reactor 3% but possibility of improvement
• What can only neutrino do: • Independent method looking directly at the nuclear core, from outside• Cross calibration of different power plants from different sites
With Double Chooz NearAverage power measurement
of both reactors: 5-6% over 3 weeks
Fig: Chooz cooling tubes
= Assuming no knowledge on reactor (neither power nor fuel composition)
Following up the burn-upFollowing up the burn-up
Days
235U
239Pu
238U 241PuFis
sion
pe
rce
ntag
es
Evis in MeV
# an
ti- e
in 1
0 da
ys
Detector efficiency included.
Average spectra (analytical estimations), no statistical fluctuations here
Question: How far can we see two different burn-up?
Try to answer with non-parametric statistical test: Kolmogorov-Smirnov
Days
235U
239Pu
238U 241PuFis
sion
pe
rce
ntag
es
Evis in MeV
# an
ti- e
in 3
wee
ks
- 9980 events- 9370 events
Two extreme burn-up inTwo extreme burn-up in3 weeks3 weeks (identical reactors)(identical reactors)
Prelim
inary
2 fixed fuel compositions (in fraction of fission per isotope) 235U=0.66 239Pu=0.24 238U=0.08 241Pu=0.02 235U=0.47 239Pu=0.37 238U=0.08 241Pu=0.08
Kolmogorov-Smirnov Test on Burn-up:Null hypothesis H0: the two “burn-up” induce identical anti-e spectra
• Shape only: PKS = 0.81 (Max Distance = 0.0093) Shapes are very close!!!
• Rate and shape: PKS = 1.3 x 10-4 Rates are very different (~7% diff. on # of anti-e)
Evis in MeV
# an
ti- e
in 1
0 da
ys
- 4750 events- 4460 events
Two extreme Burn-up inTwo extreme Burn-up in10 days10 days (identical reactors)(identical reactors)OR OR 16 days 16 days with R1with R1 ONON R2R2 OFF OFFOROR 29 days 29 days with R1with R1 OFF OFF R2R2 ONON
Days
235U
239Pu
238U 241PuFis
sion
pe
rce
ntag
es
Prelim
inary
2 fixed fuel compositions (in fraction of fission per isotope) 235U=0.66 239Pu=0.24 238U=0.08 241Pu=0.02 235U=0.47 239Pu=0.37 238U=0.08 241Pu=0.08
Kolmogorov-Smirnov Test on Burn-up:Null hypothesis H0: the two “burn-up” induce identical anti-e spectra
• Shape only: PKS = 0.99 (Max Distance = 0.0093) Shapes look identical!!!
• Rate and shape: PKS = 1.8 x 10-2 Rates are different (~7% diff. on # of anti-e)
Evis in MeV
# an
ti- e
in 3
wee
ks
- 9980 events- 9600 events
Two closer burn-up inTwo closer burn-up in3 weeks3 weeks (identical reactors)(identical reactors)
Days
235U
239Pu
238U 241PuFis
sion
pe
rce
ntag
es
Prelim
inary
2 fixed fuel compositions (in fraction of fission per isotope) 235U=0.66 239Pu=0.24 238U=0.08 241Pu=0.02 235U=0.54 239Pu=0.32 238U=0.08 241Pu=0.06
Kolmogorov-Smirnov Test on Burn-up:Null hypothesis H0: the two “burn-up” induce identical anti-e spectra
• Shape only: PKS = 0.997 (Max Distance = 0.006) Shapes look identical!!!
• Rate and shape: PKS = 4.2 10-2 Rates are different (~4 % diff. on # of anti-e)
Evis in MeV
# an
ti- e
in 3
wee
ks
- 9980 events- 9800 events
Two still closer burn-up inTwo still closer burn-up in3 weeks3 weeks (identical reactors)(identical reactors)
Days
235U
239Pu
238U 241PuFis
sion
pe
rce
ntag
es
Prelim
inary
2 fixed fuel compositions (in fraction of fission per isotope) 235U=0.66 239Pu=0.24 238U=0.08 241Pu=0.02 235U=0.61 239Pu=0.28 238U=0.08 241Pu=0.03
Kolmogorov-Smirnov Test on Burn-up:Null hypothesis H0: the two “burn-up” induce identical anti-e spectra
• Shape only: PKS = 1.00 (Max Distance = 0.002) Looks identical!!!
• Rate and shape: PKS = 0.55 Rates are too close, spectra match (~2 % diff. on # of anti-e)
Conclusion & OutlookConclusion & Outlook
- Neutrinos could “take a picture” of the nuclear cores Thermal power measurement & non proliferation applications
- Thermal power measurement will rely on the absolute normalization (but time-relative measurement of interest for burn-up, cross calibration)
- Non proliferation applications will rely on time-relative measurements (try to detect an ‘abnormal’ burn-up)
- Double Chooz Near detector will provide an unrivalled anti-e spectrum measurement. These data will be an incredibly rich source of information in order to look for power, burn-up correlations with anti-e spectra as a first step toward isotopic core composition.
- However more precise determination of reactor power and some hints of isotopic composition might be obtained only with a closer detector to a single reactor.
Thank you for your attention!
It’s time for lunch now!
SystematicsSystematics
(Total ~0.45% without contingency ….)
(see next slide)
Measured with several methods
‘’identical’’ Target geometry & LS
Same scintillator batch + Stability
Accurate T control (near/far)
Same weight sensor for both det.
Distance measured @ 10 cm + monitor core barycenter
Two ‘’identical’’ detectors,
Low bkg
< 0.6 %2.7 %Total
0.2 - 0.3 %1.5 %From 7 to 3 cutsAnalysis
<0.1 %1.0 %Spatial effects
<0.2%1.2 %H/C ratio &
Gd concentration
<0.1 %0.3 %Density
<0.1 %0.3 %Solid angle
0.25 %few %Live time
0.2 %0.3 %Target Mass
Detector - induced
<0.1 %0.6 %Energy per fission
<0.1 %0.7 %Reactor power
<0.1 %1.9 % flux and Reactor-induced
Double Chooz (relative)Chooz
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