The Double Chooz reactor neutrino experiment Thomas Mueller – CEA Saclay Irfu/SPhN 19 March 2009 Thomas Mueller - Workshop AAP09

Thomas Mueller - Workshop AAP09 Overview Neutrino oscillation Theory & status Neutrino oscillation @ reactor The Double Chooz experiment From Chooz to Double Chooz Neutrino detection and detector design Present status of the experiment Errors & expected sensitivity Summary & conclusion 19 March 2009 Thomas Mueller - Workshop AAP09

Neutrino oscillations Super-Kamiokande (1998) → first evidence of neutrino oscillation, non-zero mass Oscillations are described by a mixing of flavour and mass eigenstates through unitary PMNS matrix 6 parameters: 3 mixing angles, 2 mass differences & 1 complex phase Atmospheric ν CHOOZ experiment Solar ν 19 March 2009 Thomas Mueller - Workshop AAP09

Current knowledge on neutrino mixing parameters T. Schwetz et al. NewJ.Phys.10:113011,2008 Experimental measurements Best global limit on θ13 Global (90% CL) sin2θ13 < 0.035 G.L. Fogli et al. Phys.Rev.Lett.101:141801,2008 Hints for θ13 > 0 sin2θ13 = 0.016 ± 0.010 (1σ) 19 March 2009 Thomas Mueller - Workshop AAP09

Reactor neutrino oscillations DC near detector DC far detector Nucifer Chooz KamLAND 19 March 2009 Thomas Mueller - Workshop AAP09

From Chooz (1997-1998) to Double Chooz Neutrino disappearance experiment 5 m3 of Gd-doped liquid scintillator L = 1.05 km Highest systematic uncertainty → antineutrino flux emitted by reactor Double Chooz: from absolute to relative measurement R = 1.01 ± 2.8% (stat) ± 2.7% (syst) sin22θ13 < 0.15 @ Δm312=2.5 10-3 eV2 (90% CL) 19 March 2009 Thomas Mueller - Workshop AAP09

The Double Chooz collaboration Spokesman: Hervé de Kerret (APC) France: APC Paris, CEA/Irfu Saclay, Subatech Nantes, Strasbourg Japan: HIT, Kobe, MUE, Niigata, TGU, TIT, TMU, Tohoku Germany: Aachen, MPIK Heidelberg, TU München, EKU Tübingen, Hamburg Russia: RAS, RRC Kurchatov Institute USA: Alabama, ANL, Chicago, Columbia, Drexel, Illinois, Kansas, LLNL, LSU, Notre Dame, Sandia, Tennesses, UCD Spain: CIEMAT Madrid UK: Univ. Sussex Brazil: CBPF, UNICAMP Collaboration meeting @ Chooz (June 2008) 19 March 2009 Thomas Mueller - Workshop AAP09

The Double Chooz experiment 2 « identical » detectors Far detector (1050m) ν oscillation 300 m.w.e. Near detector (400m) Flux normalization 115 m.w.e. Phase I (2010-2011) Far detector only Phase II (2011…) 2 detectors near and far 2 PWR-N4 2 x 4.27 GW ~ 1021 ν/s Chooz B nuclear power plant Ardennes, France 19 March 2009 Thomas Mueller - Workshop AAP09

Antineutrinos detection Inverse β decay: Clear signature of an antineutrino reaction in the detector → powerful background suppression Prompt signal: photons from e+e- annihilation Delayed signal: photons from n capture on Gd Δt ~ 30 µs, E ~ 8 MeV 19 March 2009 Thomas Mueller - Workshop AAP09

Thomas Mueller - Workshop AAP09 Detector design Acrylic target vessel 10.3 m3 Gd-doped LS Acrylic γ-catcher vessel 22.6 m3 LS Stainless steel Buffer 110 m3 mineral oil ~ 400 PMT Inner veto 90 m3 LS ~ 80 PMT Shielding 15 cm steel Outer veto plastic scintillator panels Calibration glove-box (εdet ~ 80%) 19 March 2009 Thomas Mueller - Workshop AAP09

Far lab integration (1/2) June 08: Start of the work Sept 08: Shielding installation Nov 08: IV integration Dec 08 - Jan 09: Lab cleaning 19 March 2009 Thomas Mueller - Workshop AAP09

Far lab integration (2/2) Feb 09: IV cleaning… … ISO6 class tent mounting… … and IV PMTs installation Presently: Buffer installation First neutrino planned for end 2009 19 March 2009 Thomas Mueller - Workshop AAP09

Thomas Mueller - Workshop AAP09 Near lab preparation Site engineering study complete Tender process for construction soon Schedule: lab is finished in 2010 19 March 2009 Thomas Mueller - Workshop AAP09

Statistical & systematic errors CHOOZ: R = 1.01 ± 2.8% (stat) ± 2.7% (syst) CHOOZ Double Chooz Target volume 5.55 m3 10.3 m3 Target composition 6.77 1028 H/m3 6.55 1028 H/m3 Data taking period few months 3-5 years Event rate 2700 FD 40000/3y - ND 106/3y Statistical error 2.8% 0.5% Statistical error Systematic error Two identical detectors σsys=0.6% 19 March 2009 Thomas Mueller - Workshop AAP09

Expected θ13 sensitivity CHOOZ limit is reached in 1 month! Phase I Phase II σsys=2.5% σsys=0.6% sin22θ13 < 0.03 sin22θ13 < 0.06 19 March 2009 Thomas Mueller - Workshop AAP09

Summary and conclusions First new generation neutrino experiment using two identical detectors at different distances to measure θ13 Far detector installation in progress → first neutrino end 2009 Far detector only: sin22θ13 < 0.06 in 1.5 years (90% CL) if no oscillation Far and near detectors: sin22θ13 < 0.03 in 3 years (90% CL) if no oscillation 19 March 2009 Thomas Mueller - Workshop AAP09