Chasing 13 with new experiments at nuclear reactors

Chasing 13 with new experiments

at nuclear reactors

Thierry Lasserre Saclay

NuFact04, OsakaJuly 26 2004

T.L. (Saclay) - NuFact04 -

The neutrino sector

[m221 - 12] – [m2

32 - 23] – sign(m232) - 13 -

superbeam +

reactor

sin2(213)<0.20 (CHOOZ) 13 ?(small angle)

Hierarchy sign(m232 ) ?

CP violation phase ?

solar +

KamLAND+

reactor ?

MSW-LMA

m212~O(10-4/-5) eV2

sin2(212)~0.8(large angle)

atmospheric +

K2K+

MINOS – Superbeams …

m232~2-3 10-3 eV2

sin2(223)~1(maximal angle)

But no absolute mass scale coming from oscillation experiments --> & 0 decays ?


Measurement at reactors&

complementarity with LBL


e disappearance experiment

Pth= 8.5 GWth, L = 1,1 km, M = 5t (300 mwe)

Best current constraint: CHOOZ

World best constraint !

@m2atm=2 10-3 eV2

sin2(2θ13)<0.2

(90% C.L)

e x

R = 1.01 2.8%(stat)2.7%(syst)

M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374

http://babbage.sissa.it/find/hep-ex/1/au:+Apollonio_M/0/1/0/all/0/1



13 & beam experiments

LBL disappearance : sin2(223) 2 solutions : 23 & /2-23

|m213| 2 solutions m1>m3 or m3>m1

Appearance probability :

• K1,K2,K3: constants known with experimental errors)• dependence in sin(223), sin(23) 2 solutions• dependence in sign(m2

31) 2 solutions• -CP phase [0,2] interval of solutions

P( e) ~ K1 sin2(23 ) sin2(213 ) + K2 sin(223 ) sin(13 ) sign(m2

31) cos() K3 sin(223 ) sin(13 ) sin ()

13 & reactor experiments• <E> ~ a few MeV only disappearance experiments

sin2(213) measurement independent of -CP

• 1-P(e e) = sin2(213)sin2(m231L/4E) + O(m2

21/m231)

weak dependence in m221

• a few MeV e + short baselines negligible matter effects (O[10-4] ) sin2(213) measurement independent of sign(m2

13)

sin

2(2

1

3 )

P( e)

beam

reactor


CP- phase induced ambiguity

0

0.01

0.06 0.1 0.14

0.03

0.05

0.07

sin2(213)

P(

e

)

)sin(2θ

δsin 0.11)(2θsin

2

1)νP(ν

1313

2eμ

T2K measurement

()P

sin correlation


23 induced ambiguity

0

0.01

0.06 0.1 0.14

0.03

0.05

0.07

sin2(213)

P(

e

) T2K measurement

0.4)(θsin

0.6)(θsin0.95)(2θsin

232

232

232

reactor measurement

LBL + reactor combination might help to solve the 23 degeneracy


Improving CHOOZ is difficult !


50 years of reactor neutrino experiments …

1956 Discovery of neutrinos @Savannah River - First detection of reactor neutrinos1990’s Reactor neutrino flux measurements1995 Nobel Prize to Fred Reines2002 Discovery of massive neutrinos and oscillations confirmed by KamLAND

From discovery to metrology !G. Mention (APC)

Near detector Far detector


One nuclear plant & two detectors

Nuclear reactor

1,2 core(s) ON/OFF : ok 4 cores ON/OFF : no !

Near detector

5-50 tons> 50 mwe

Far detector

5-50 tons> 300 mwe

D1 = 0.1-1 km D2 = 1-3 km

e e,,

Isotropic e flux (uranium & plutonium fission fragments) Detection tag : e + p e+ + n, <E>~ 4 MeV, Threshold ~1.8 MeV Disappearance experiment: suppression+shape distortion between the 2 detectors 2 IDENTICAL detectors (CHOOZ, BOREXINO/CTF type, KamLAND)

• Minimise the uncertainties on reactor flux & spectrum (2 % in CHOOZ)• Cancel cross section uncertainties • Challenge: relative normalisation between the two detectors < 1% !


Improving CHOOZ is difficult …

@CHOOZ: R = 1.01 2.8%(stat)2.7%(syst)

Statistics Increase luminosity L = t x P(GWth) x Np(target) Increase fiducial volume & exposure ~2700 events in CHOOZ but >40,000 for the next experiment σ < 0.5%

Experimental error 2 detectors cancel neutrino flux and cross section systematic uncertainty [~2%] Identical detectors decrease detector systematic uncertainties [<1%] Movable VS non movable detectors : cross calibration, but error might be increased ?

Backgrounds (S/N~25 in CHOOZ ; Goal S/N >100 in the new experiment) Uncorrelated background (measurement in-situ) – Correlated backgrounds ( induced) Underground site required: >300 m.w.e for the far site to improve CHOOZ S/N equivalent for Near and Far detector (near detector could be shallower) Reactor ON/OFF measurement 1, 2, 4, or up to 7 reactor cores ?


nepe

Reactor antineutrino detection

prompt event:delayed event:

MeV)2.2( dpn

E prompt E En 0.8 MeV

• Prompt e+, EP=1-8 MeV, visible energy

• Delayed neutron capture on Gd, ED=8 MeV

• Prompt(/) - Delayed(/) pulse shape discrimination

Time correlation: 30sec

Space correlation: < 1m3

Anti-e tag: e + p e+ + n, Q~1.8 MeV Threshold

Or Gd capture (8 MeV)


Why two identical detectors …u

nlo

ad

ed

Gd

~0.1

%

scin

tillato

r

signal No signal

e+

n

Gdn

Gd

e+

e+

H

n

e+

H

n

=

0 % In

tera

ctio

n

=

100 %

spill in/out effect

Acrylic vessel

A ~1% irreducible systematic error from the spill in/out effect Boundary effect 2 identical inner vessels

Scintillator doped with 0.1% Gd MUST be perfectly stable over the life time of the experiment (>5 years)

Fiducial volume


Observable: e+ spectrum (Double-CHOOZ configuration)

sin2(213)=0.04 sin2(213)=0.1 sin2(213)=0.2

sin2(213)=0.04 sin2(213)=0.1 sin2(213)=0.2

m2atm = 2.0 10-3 eV2

Near Detector: ~ 1.8 106 events-Reactor efficiency: 80%-Detector efficiency: 80%-Dead time: 50%

Far Detector: ~ 34 000 events-Reactor efficiency: 80%-Detector efficiency: 80%

E (MeV) E (MeV)

Events

/20

0 K

eV

/3 y

ears


Example of e oscillation at reactor

(Double-CHOOZ configuration )Rate + shape information if 13 not too small

@1,05 km

Far/

Near

energ

y b

in

rati

o

Note: optimum baseline ~1.5km


Detector size scale

Borexino300 t

KamLAND1000 t

Reactor/13

Example ~20 tCHOOZ

5 tDoubleCHOOZ

&KASKA

(10 tons)

X 2

Angra, Daya-Bay, Braidwood


90% C.L. sensitivity if sin2(213)=0

Reactor1 (0.5 km, 2.3 km): ~13 tonsPXE x 10 GW x 3 years sin2(213)<~0.02, 90% C.LReactor2 (0.5 km, 2.3 km): ~270 tonsPXE x 10 GW x 3 years sin2(213)<~0.01, 90% C.L

T2K

Huber, Lindne

r, Schw

etz & W

inter: hep-ph/0303

232

G. M

en tion &

T. L.

σbkg

σbkg

σbkg

reactor 1 (2 RNU) reactor 2 (40 RNU)

1%

0.1%

@m2=2.0 10-3 eV2

RNU = Reactor Neutrino Unit : 1 RNU = 1031 free H GWth year


Huber, Lindner, Schwetz & Winter (‘extremum’ of projection of the 2 manifold on the sin2(213) axis)

Double-CH1313Z

sin2(213) at LBL & reactors

CHOOZ alone90% C.L

@m2=2.0 10-3 eV2

(3 ktons ?)


Current proposal for new reactor experiments …


Nuclear reactors in the world


World momentum December 2002: First European meeting, MPIK Heidelberg April 2003: Second European meeting, PCC, Paris May 2003: First international workshop, University of Alabama, US October 2003: Second international workshop, TUM, Germany March 2004: Third international workshop, Niigata, Japan Next workshop in Brazil, January 2005

125 authors, 40 Institutions White Paper Report on Using Nuclear Reactors to search for a value of theta 13 hep-ex/0402041


Which site for the experiment ?

Diablo Canyon

Braidwood

Angra

PenlyChoozCruas

Krasnoyarsk

Taiwan

Kashiwasaki

One reactor complexTwo underground cavities @0.1-1 km & ~1-2 km

Daya bay


The Krasnoyarsk site: Kr2DetRussian Research Center “Kurchatov Institute”

Completely underground facility was used by the Soviets for weapons production.

Single reactor core P=1.6 GWth

ON/OFF cycle [50 days ON & 7 days OFF]

No civil construction

>50 tons detectors Near: >50 tons – 115 m – 600 mwe Far: >50 tons - 1.1 km - 600 mwe

Sensitivity 0.5% systematic error sin2(213) < 0.015 (m2 =2.5 10-3 eV2, 90%

C.L.)

Prospects Visit in summer 2003 cancelled by Russian

authorities Site not available for “political” reasons


Current proposals

Braidwood

Angra

Double-Chooz

Kaska

Daya bay

1st generation: sin2(213)~0.01-0.03

2nd generation: sin2(213)~0.01 + shape only analysis


Braidwood (Illinois)Two reactor cores P=2 x 3.6 GWth

Civil construction Flat topology Near & Far: 120m shafts (10m diameter) + laboratories (25-35 M$)

Two 50 tons detectors Near: 25-50 tons – 300 m – 450 mwe Far: 25-50 tons – 1.5-1.8 km - 450 mwe Movable detector (move on the surface, lift with crane)

3 years Sensitivity 0.5% systematic error No signal: sin2(213) < 0.01 (90% C.L.)

Prospects (not yet approved) Construction in 39 month - running in 2009. Cost ~45 M$ Geological studies ongoing


Braidwood (Illinois)

Civil construction

Detector sketch

ANL, Chicago, Columbia, FNAL, Kansas, Oxford, Pittsburgh, Texas


Daya BayFour reactor cores P=4 x 2.9 = 1.6 GWth

+ two new cores for 6 GWth in 2011

Civil construction Near: 1 km tunnel + laboratory Far: 2 km tunnel + laboratory

~10 tons detector modules Near: 25 tons - 300 m – 200 mwe Far: 50 tons - 1.5-1.8 km - 700 mwe Movable detector concept

Sensitivity 0.4% systematic error sin2(213) < ~ 0.01 (90% C.L.) ?

Prospects (not yet approved) 2004-05: R&D, 2006-07: Construction 1 Near detector running in 2008 Geological & safety studies ongoing


Daya Bay

Near detector: 2 x 10 tons modulesFar detector: 4 x 10 tons modules 3 years of data takingsin2(213) < ~ 0.01-0.02 (90% C.L.)

IHEP, CIAE, Tsinghua Univ., Hong Kong Univ., Hong Kong Chinese Univ, (Berkeley, Caltech) R&D


Kaska (Kashiwasaki, Japan)Seven reactor cores P=24.3 GWth 2 near detector mandatory

Civil construction 2 Near: ~70 m 6m shafts + laboratories Far: ~250 m 6m shaft + laboratory

Multiple detectors 2 Near: 8 tons – 300-400 m – 100 mwe Far: 8 tons - 1.3-1.8 km - 500 mwe

Sensitivity 0.5% systematic error sin2(213) < 0.025 (90% C.L.)

Prospects (not yet approved) 2004-05: R&D, 2006-07: Construction. Running in 2008. Cost ~20 M$ Geological studies ongoing – Prototype to be built for R&D.


KASKA (Japan)Tohoku Univ., Niigata Univ., Rikkyo Univ., KEK, Kobe Univ.Tokyo Institute of Technology, Tokyo Metropolitan Univ.

Sensitivity (3 years): sin2(213)<0.026 @90%

C.L


Near site: D~100-200 m, overburden 50-80 mweFar site: D~1.1 km, overburden 300 mwe

Type PWR

Cores 2

Power 8.4 GWth

Couplage 1996/1997

(%, in to 2000) 66, 57

Constructeur Framatome

Opérateur EDF

Chooz-Far

Chooz-Near

Double-Chooz (France)


Double-Chooz featuresTwin reactor cores N4 type P=2x4.2 GWth

Civil construction Near: 20x10x5m experimental hall Artificial overburden

Two 10 tons detectors Near: 100-200 m – 60-80 mwe Far: 1.05 km - 300 mwe

3 years Sensitivity 0.6% systematics No signal: sin2(213) < 0.02-03 (90% C.L.)

Signal: sin2(213) > 0.04-05 (3σ)

Prospect (approved & funded in France) 2007: far detector running 2008: near detector running Cost ~7Meuros + civil constr.

Near detector site (to be built)

Existing Far detector site

@DAPNIA


The CHOOZ-far detector

CHOOZ existing pit

Non scintillating buffer: scintillator+quencher(r+0.95m, , V=100 m3)

-catcher: 80% dodecane + 20% PXE (acrylic, r+0,6m – V= 28,1 m3)

7 m

7 m

PMT supporting structure

Muon VETO: scintillating oil (r+0.6 m – V=110 m3)

7 m

Shielding: 0,15m steel

target: 80% dodecane + 20% PXE + 0.1% Gd (acrylic, r=1,2m, h = 2,8m, 12,7 m3)

@DAPNIA


Reactor induced systematics

systematics Error type CHOOZFuture

Experiment

2 identical detectorLow background

Reactor

Flux, cross section 1.9% - O(0.1%)

Thermal power 0.7% - O(0.1%)

E/Fission 0.6% - O(0.1%)

2.1% - O(0.1%)

2 detectors cancellation of the reactor physical uncertainties


Detector induced systematics

systematics Error type CHOOZFuture

Experiment

Sim.Monte-Carlo

2 identical detectorLow backgrounds

Detector

Scintillator density 0.3% 0.3% O(0.1%)

% H 1.2% 1.2% O(0.1%)

Target volume 0.3% 0.2% 0.2%

« Spill in/out » effect 1.0% 1.0% X O(0.1%)

Live time ? 0.25% 0.25%

M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374

A single scintillator batch will be prepared to fill both detectors with the same apparatus




Relative Normalisation: Analysis

@CHOOZ: 1.5% systematic error - 7 analysis cuts- Efficiency ~70%

Sélection cuts - positron energy [energy threshold]

- e+ position/géode (30cm) [position reconstruction] - neutron energy [energy cut - calibration] - n pos./géode (30 cm) [position reconstruction] - distance e+ - n [position reconstruction] - t e+ - n [neutron capture on Gd] - n multiplicity [level of accidental background]

Goal Double-CHOOZ: <0.5% systematic error - 2 to 3 analysis cut

Sélection cuts - neutron energy

(- distance e+ - n ) [level of accidentals] - t e+ - n


Attempt to compare Double-Chooz with T2K (3σ discovery potential)

sin22θ13 = 0.14 sin22θ13 = 0.08 Sin2(2θ13) = 0.04

Double-CHOOZ starts with two detectors in January 2008T2K starts at FULL intensity in January 2010Assumption

From Huber, Lindner, Schwetz (hep/0405032) 90% C.L.

3σ C.L.


Letter of Intent

Th. Lasserre

+ Univ. Alabama - Univ. Louisiana - Univ. Tennessee - Univ. Drexel – Argonne


Double-Chooz & IAEA IAEA :Intenational Agency for Atomic Energy

Missions: Safety & Security, Science & Technology, Safeguard & Verification Control that member states do no use civil installations with military goals (production of plutonium !)

•Control of the nuclear fuel in the whole fuel cycle *•Fuel assemblies, rods, containers * (*Anti-neutrinos could play a role!)•Distant & unexpected controls of the nuclear installations *

Why IAEA is interested to antineutrino ? •IAEA wants the « state of the art »methods for the future !•Cost issue … 10,000$/day/inspector …

AIEA wants a feasibility study on antineutrinos•Monitoring of the reactors with a Double-Chooz like detector ?•Monitoring a country – new reactors “à la KamLAND”

Double-CHOOZ-IAEA: CEA/Saclay + Subatech Nantes + Kurchatov

•Perform new antineutrino spectrum @ILL reactor•Use Double-Chooz near as a ‘prototype’ for nuclear reactor monitoring•Other studies like large and very large underwater antineutrino detectors …


Towards evidence of non vanishing

H. M

inakata

& H

. Sugiy

am

a, h

ep-p

h/0

30

93

23

• T2K: 10 years running (0.75MW beam & Super-Kamiokande)• Reactor (second generation): 103 104 GWth.ton.year

Regions consistent with the hypothesis =0 (90% CL)

By the reactor-LBL combined measurement

Reactor [103 GW.t.y]@ ~1km200 tons10 GWth

5 years


Single reactor core P=4.1 GWth A new core is being built (2006)

Civil construction Near: 6x6x60m tunnel + 10x10x12m exp. hall Far: 6x6x450m tunnel + 10x10x12m exp. hall + emergency shafts

Two >100 tons detector Near: 300 m – 50 mwe ? Far: 1.35 km - 600 mwe Non movable detectors concept

Sensitivity 5 years >103 GWth.t.y

sin2(213) < 0.01 (90% C.L.) 1% systematic error Shape only analysis

2nd generation project: Angra (Brazil)Argonne + Brazil : CBPF, UNICAMP, USP, PUC-

RIO


Conclusion & outlook A new reactor neutrino experiment could provide an evidence

of the oscillation in the (1,3) sector in 2009

Reactor & LBL programs provide independent and complementary measurements of 13. But current proposals have low synergy …

Of course reactor experiments won’t replace the rich LBL program. However, a preliminary value of 13 might help to design the best CP- detector:

Several projects of reactor experiment & strong world momentum First generation : sensitivity sin2(213)~0.02-0.03 - Rate + Shape

Motionless detectors: Double-Chooz (funded in France), KASKA Movabledetectors: Daya-bay, Braidwood

Second generation : sensitivity sin2(213)<0.01 - Shape only (>103

GWth.tons.years): Motionless detectors: Angra

)()()2sin(

1

)2sin(

)sin(1.0

)()(

)()(2/1

1313

syststatNPP

PPA

ee

eecp

Documents

Chasing 13 with new experiments at nuclear reactors