Chasing  13 with new experiments at nuclear reactors Thierry Lasserre Saclay NuFact04, Osaka July

T.L. (Saclay) - NuFact04 - The neutrino sector [  m  12 ] – [  m  23 ] – sign(  m 2 32 ) -  13 -  superbeam + reactor sin 2 (2  13 )<0.20 (CHOOZ)   13 ? (small angle) Hierarchy  sign(  m 2 32 ) ? CP violation   phase ? solar + KamLAND + reactor ? MSW-LMA  m 2 12 ~O(10 -4/-5 ) eV 2 sin 2 (2  12 )~0.8 (large angle) atmospheric + K2K + MINOS – Superbeams …  m 2 32 ~ eV 2 sin 2 (2  23 )~1 (maximal angle) But no absolute mass scale coming from oscillation experiments -->  &  0 decays ?

T.L. (Saclay) - NuFact04 - Measurement at reactors & complementarity with LBL

T.L. (Saclay) - NuFact04 - e disappearance experiment P th = 8.5 GW th, L = 1,1 km, M = 5t (300 mwe) Best current constraint: CHOOZ World best constraint  m 2 atm = eV 2 sin 2 (2θ 13 )<0.2 (90% C.L) e  x R = 1.01  2.8%(stat)  2.7%(syst) M. ApollonioM. Apollonio et. al., Eur.Phys.J. C27 (2003)

T.L. (Saclay) - NuFact04 -  13 & beam experiments LBL  disappearance : sin 2 (2  23 )  2 solutions :  23 &  /2-  23 |  m 2 13 |  2 solutions m 1 >m 3 or m 3 >m 1 Appearance probability : K 1,K 2,K 3 : constants known with experimental errors) dependence in sin(2  23 ), sin(  23 )  2 solutions dependence in sign(  m 2 31 )  2 solutions  -CP phase  [0,2  ]  interval of solutions P(   e ) ~ K 1 sin 2 (  23 ) sin 2 (2  13 ) + K 2 sin(2  23 ) sin(  13 ) sign(  m 2 31 ) cos(  )  K 3 sin(2  23 ) sin(  13 ) sin (  )  13 & reactor experiments ~ a few MeV  only disappearance experiments  sin 2 (2  13 ) measurement independent of  -CP 1-P( e  e ) = sin 2 (2  13 )sin 2 (  m 2 31 L/4E) + O(  m 2 21 /  m 2 31 )  weak dependence in  m 2 21 a few MeV e + short baselines  negligible matter effects (O[10 -4 ] )  sin 2 (2  13 ) measurement independent of sign(  m 2 13 ) sin 2 (2  13 ) P(   e ) beam reactor

T.L. (Saclay) - NuFact04 - CP-  phase induced ambiguity sin 2 (2  13 ) P(   e ) T2K measurement sin  correlation

T.L. (Saclay) - NuFact04 -  23 induced ambiguity sin 2 (2  13 ) P(   e ) T2K measurement reactor measurement LBL + reactor combination might help to solve the  23 degeneracy

T.L. (Saclay) - NuFact04 - Improving CHOOZ is difficult !

T.L. (Saclay) - NuFact years of reactor neutrino experiments … 1956  Discovery of River - First detection of reactor neutrinos 1990’s  Reactor neutrino flux measurements 1995  Nobel Prize to Fred Reines 2002  Discovery of massive neutrinos and oscillations confirmed by KamLAND From discovery to metrology ! G. Mention (APC) Near detector Far detector

T.L. (Saclay) - NuFact04 - 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 D 1 = km D 2 = 1-3 km e e, ,  Isotropic e flux (uranium & plutonium fission fragments) Detection tag : e + p  e + + n, ~ 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% !

T.L. (Saclay) - NuFact04 - Improving CHOOZ is difficult R = 1.01  2.8%(stat)  2.7%(syst)  Statistics Increase luminosity L =  t x P(GW th ) x N p (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 ?

T.L. (Saclay) - NuFact04 - Reactor antineutrino detection prompt event: delayed event: Prompt e+, E P =1-8 MeV, visible energy Delayed neutron capture on Gd, E D =8 MeV Prompt(  /  ) - Delayed(  /  )  pulse shape discrimination Time correlation:   30  sec Space correlation: < 1m 3 Anti- e tag: e + p  e + + n, Q~1.8 MeV Threshold Or Gd capture (8 MeV)

T.L. (Saclay) - NuFact04 - Why two identical detectors … unloaded Gd ~0.1% scintillator signalNo signal e + n Gd n e + H n H n  = 0 % Interaction  = 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

T.L. (Saclay) - NuFact04 - Observable: e + spectrum (Double-CHOOZ configuration) sin 2 (2  13 )=0.04 sin 2 (2  13 )=0.1 sin 2 (2  13 )=0.2 sin 2 (2  13 )=0.04 sin 2 (2  13 )=0.1 sin 2 (2  13 )=0.2  m 2 atm = eV2 Near Detector: ~ events -Reactor efficiency:80% -Detector efficiency:80% -Dead time:50% Far Detector: ~ events -Reactor efficiency:80% -Detector efficiency:80% E (MeV) Events/200 KeV/3 years

T.L. (Saclay) - NuFact04 - Example of e oscillation at reactor (Double-CHOOZ configuration ) Rate + shape information if  13 not too km Far/Near energy bin ratio Note: optimum baseline ~1.5km

T.L. (Saclay) - NuFact04 - Detector size scale Borexino 300 t KamLAND 1000 t Reactor/  13 Example ~20 t CHOOZ 5 t Double CHOOZ & KASKA (10 tons) X 2 Angra, Daya-Bay, Braidwood

T.L. (Saclay) - NuFact % C.L. sensitivity if sin 2 (2  13 )=0 Reactor 1 (0.5 km, 2.3 km): ~13 tons PXE x 10 GW x 3 years  sin 2 (2  13 )<~0.02, 90% C.L Reactor 2 (0.5 km, 2.3 km): ~270 tons PXE x 10 GW x 3 years  sin 2 (2  13 )<~0.01, 90% C.L T2K Huber, Lindner, Schwetz & Winter: hep-ph/ G. Men tion & T. L. σ bkg reactor 1 (2 RNU)reactor 2 (40 RNU) 1%  m 2 = eV 2 RNU = Reactor Neutrino Unit : 1 RNU = free H GW th year

T.L. (Saclay) - NuFact04 - Huber, Lindner, Schwetz & Winter (‘extremum’ of projection of the  2 manifold on the sin 2 (2  13 ) axis) Double-CH  13  13 Z sin 2 (2  13 ) at LBL & reactors CHOOZ alone 90%  m 2 = eV 2 (3 ktons ?)

T.L. (Saclay) - NuFact04 - Current proposal for new reactor experiments …

T.L. (Saclay) - NuFact04 - Nuclear reactors in the world

T.L. (Saclay) - NuFact04 - 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 authors, 40 Institutions White Paper Report on Using Nuclear Reactors to search for a value of theta 13 hep-ex/

T.L. (Saclay) - NuFact04 - Which site for the experiment ? Diablo Canyon Braidwood Angra Penly Chooz Cruas Krasnoyarsk Taiwan Kashiwasaki One reactor complex Two underground km & ~1-2 km Daya bay

T.L. (Saclay) - NuFact04 - The Krasnoyarsk site: Kr2Det Russian Research Center “Kurchatov Institute” Completely underground facility was used by the Soviets for weapons production. Single reactor core P=1.6 GW th 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 km mwe Sensitivity 0.5% systematic error sin 2 (2  13 ) < (  m 2 = eV 2, 90% C.L.) Prospects Visit in summer 2003 cancelled by Russian authorities Site not available for “political” reasons

T.L. (Saclay) - NuFact04 - Current proposals Braidwood Angra Double-Chooz Kaska Daya bay 1 st generation: sin 2 (2  13 )~ nd generation: sin 2 (2  13 )~ shape only analysis

T.L. (Saclay) - NuFact04 - Braidwood (Illinois) Two reactor cores P=2 x 3.6 GW th Civil construction Flat topology Near & Far: 120m shafts (10m diameter) + laboratories (25-35 M$) Two 50 tons detectors Near: tons – 300 m – 450 mwe Far: tons – km mwe Movable detector (move on the surface, lift with crane) 3 years Sensitivity 0.5% systematic error No signal: sin 2 (2  13 ) < 0.01 (90% C.L.) Prospects (not yet approved) Construction in 39 month - running in Cost ~45 M$ Geological studies ongoing

T.L. (Saclay) - NuFact04 - Braidwood (Illinois) Civil construction Detector sketch ANL, Chicago, Columbia, FNAL, Kansas, Oxford, Pittsburgh, Texas

T.L. (Saclay) - NuFact04 - Daya Bay Four reactor cores P=4 x 2.9 = 1.6 GW th + two new cores for 6 GW th in 2011 Civil construction Near: 1 km tunnel + laboratory Far: 2 km tunnel + laboratory ~10 tons detector modules Near: 25 tons m – 200 mwe Far: 50 tons km mwe Movable detector concept Sensitivity 0.4% systematic error sin 2 (2  13 ) < ~ 0.01 (90% C.L.) ? Prospects (not yet approved) : R&D, : Construction 1 Near detector running in 2008 Geological & safety studies ongoing

T.L. (Saclay) - NuFact04 - Daya Bay Near detector: 2 x 10 tons modules Far detector: 4 x 10 tons modules 3 years of data taking sin 2 (2  13 ) < ~ (90% C.L.) IHEP, CIAE, Tsinghua Univ., Hong Kong Univ., Hong Kong Chinese Univ, (Berkeley, Caltech) R&D

T.L. (Saclay) - NuFact04 - Kaska (Kashiwasaki, Japan) Seven reactor cores P=24.3 GW th 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 – m – 100 mwe Far: 8 tons km mwe Sensitivity 0.5% systematic error sin 2 (2  13 ) < (90% C.L.) Prospects (not yet approved) : R&D, : Construction. Running in Cost ~20 M$ Geological studies ongoing – Prototype to be built for R&D.

T.L. (Saclay) - NuFact04 - KASKA (Japan) Tohoku Univ., Niigata Univ., Rikkyo Univ., KEK, Kobe Univ. Tokyo Institute of Technology, Tokyo Metropolitan Univ. Sensitivity (3 years): sin 2 (2  13 C.L

T.L. (Saclay) - NuFact04 - Near site: D~ m, overburden mwe Far site: D~1.1 km, overburden 300 mwe TypePWR Cores2 Power8.4 GW th Couplage1996/1997 (%, in to 2000)66, 57 ConstructeurFramatome OpérateurEDF Chooz-Far Chooz-Near Double-Chooz (France)

T.L. (Saclay) - NuFact04 - Double-Chooz features Twin reactor cores N4 type P=2x4.2 GW th Civil construction Near: 20x10x5m experimental hall Artificial overburden Two 10 tons detectors Near: m – mwe Far: 1.05 km mwe 3 years Sensitivity 0.6% systematics No signal: sin 2 (2  13 ) < (90% C.L.) Signal: sin 2 (2  13 ) > (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

T.L. (Saclay) - NuFact04 - The CHOOZ-far detector CHOOZ existing pit Non scintillating buffer: scintillator+quencher (r+0.95m,, V=100 m 3 )  -catcher: 80% dodecane + 20% PXE (acrylic, r+0,6m – V= 28,1 m 3 ) 7 m PMT supporting structure Muon VETO: scintillating oil (r+0.6 m – V=110 m 3 ) 7 m Shielding: 0,15m steel target: 80% dodecane + 20% PXE + 0.1% Gd (acrylic, r=1,2m, h = 2,8m, 12,7 m 3

T.L. (Saclay) - NuFact04 - Reactor induced systematics systematicsError typeCHOOZ Future Experiment 2 identical detector Low background Reactor Flux, cross section1.9%-O(0.1%) Thermal power0.7%-O(0.1%) E/Fission0.6%-O(0.1%)  2.1%- O(0.1%) 2 detectors  cancellation of the reactor physical uncertainties

T.L. (Saclay) - NuFact04 - Detector induced systematics systematicsError typeCHOOZ Future Experiment Sim. Monte- Carlo 2 identical detector Low backgrounds Detector Scintillator density0.3% O(0.1%) % H1.2% O(0.1%) Target volume0.3%0.2% « Spill in/out » effect1.0% XO(0.1%) Live time?0.25% M. ApollonioM. Apollonio et. al., Eur.Phys.J. C27 (2003) A single scintillator batch will be prepared to fill both detectors with the same apparatus

T.L. (Saclay) - NuFact04 - Relative Normalisation: 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

T.L. (Saclay) - NuFact04 - Attempt to compare Double-Chooz with T2K (3σ discovery potential) sin 2 2θ 13 = 0.14 sin 2 2θ 13 = 0.08 Sin 2 (2θ 13 ) = 0.04 Double-CHOOZ starts with two detectors in January 2008 T2K starts at FULL intensity in January 2010 Assumption From Huber, Lindner, Schwetz (hep/ ) 90% C.L. 3σ C.L.

T.L. (Saclay) - NuFact04 - Letter of Intent Th. Lasserre + Univ. Alabama - Univ. Louisiana - Univ. Tennessee - Univ. Drexel – Argonne

T.L. (Saclay) - NuFact04 - 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 reactor Use Double-Chooz near as a ‘prototype’ for nuclear reactor monitoring Other studies like large and very large underwater antineutrino detectors …

T.L. (Saclay) - NuFact04 - Towards evidence of non vanishing  H. Minakata & H. Sugiyama, hep-ph/ T2K: 10 years running (0.75MW beam & Super-Kamiokande) Reactor (second generation): 10 3  10 4 GW th.ton.year Regions consistent with the hypothesis  =0 (90% CL) By the reactor-LBL combined measurement Reactor [10 3 ~1km 200 tons 10 GW th 5 years

T.L. (Saclay) - NuFact04 - Single reactor core P=4.1 GW th 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 mwe Non movable detectors concept Sensitivity 5 years  >10 3 GW th.t.y sin 2 (2  13 ) < 0.01 (90% C.L.) 1% systematic error Shape only analysis 2 nd generation project: Angra (Brazil) Argonne + Brazil : CBPF, UNICAMP, USP, PUC-RIO

T.L. (Saclay) - NuFact04 - 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 sin 2 (2  13 )~ Rate + Shape Motionless detectors: Double-Chooz (funded in France), KASKA Movabledetectors: Daya-bay, Braidwood  Second generation : sensitivity sin 2 (2  13 ) 10 3 GW th.tons.years): Motionless detectors: Angra