Double Chooz: Collaboration, Experimental concept, Detector, Physics Prospect, Status & Schedule, Summary

Small 13 leptonic CP phase Neutrino oscillations atmospheric solar Reactor Super-K+K2K+MINOS P( ) Solar+KAMLAND P( e x ) CHOOZ sin 2 (2 13 hep-ph/ e,, ( e,, ) T = U ( 1, 2, 3 ) T :U =MNS Matrix (2 mass differences, 3 angles,1complex phase) 6 parameters can be accessible from neutrino oscillation. Remains

Reactor neutrino experiment L=1.05km D=300mwe CHOOZ reactor experiment e e ( disappearance experiment) P th = 4.5 GW th, L = km, M = 5 t overburden: 300 mwe Chooz B reactor 2 cores sin =0.1 E=4MeV Measure very small deficit e

e Detection CHOOZ hep-ex/ v1 Chooz data Gd doped liquid scintillator E=1~8MeVE=8MeV ~30 s e+e+ n sin 2 (2 13 )=0.04 sin 2 (2 13 )=0.1 sin 2 (2 13 )=0.2 (0.511MeV) E ~8MeV 30μs Prompt signal Delayed signal E e = E MeV + O(E e /m n ) Gd

The next quest for 13 Chooz Result sin 2 2 m 2 =2.5x10 -3 eV 2 CHOOZ : R osc = 1.01 ± 2.8% (stat) ± 2.7% (syst) World best constraint No effect from Small Matter effect AcceleratorReactor Complementary

Double Chooz Detecctor Design/ Physics Prospects How to improve CHOOZ result? CHOOZ Result :sin 2 (2 13 )<0.2 R osc = 1.01 ± 2.8% (stat) ± 2.7% (syst)

Double Chooz Experiment Far Near ~1.05km ~ 0.4km Ardennes, France CHOOZ B Reactor Power = 4.27GW th x 2 Far Site Overhaul CHOOZ Exp. Hall 300 m.w.e 70 /day ©2009 Google Near Site 115 m.w.e 500 /day

Double Chooz Collaboration ~150 people 35 institutes, 8 countries Japan Tohoku U Tokyo Metropolitan U Niigata U Tokyo Institute of Tech. Kobe U Tohoku Gakuin U Hiroshima Inst. of Tech. France Saclay APC (collège de France) Subatech Nantes IPHC Strasbourg Germany Max planck Heidelberg Munich TU Hamburg U Tubingen U Aachen U Spain CIEMAT Madrid England Sussex Univ Russia Kurchatov inst Sc. Acad. Brasil CBPF UNICAMP Very Experienced members: Chooz, Bugey, KamLAND, Super-Kamiokande, SNO, Borexino USA Livermore nat lab Argonne Columbia Univ Chicago Univ Kansas U Notre Dame U Tennesse U Alabama U Drexel U Illinois Inst tech MIT

Double Chooz: 2 phases Timeline Construction Far Design Data Taking (Phase 1) Cstr. Near Data Taking (Phase 2) 2013 We are here now! Identical detectors cancel systematics on. Neutrino flux/Reactor power Acceptance, Cross section and etc.. Improve statistics Large target volume Longer stable operation Improve systematics Better detector design Low BG PMT/material Buffer oil/Gamma catcher Improved Cosmic-Veto detectors Phase 1:Far Detector OnlyPhase 2:Far + Near Detector Better understand of Background and Energy scale is important for the further reduction of systematic errors CHOOZ Result :sin 2 (2 13 )<0.2 R osc (=Observe/Expect)= 1.01 ± 2.8% (stat) ± 2.7% (syst)

Electronics & DAQ CEA-DSM-IRFU (thechnical coordination) Outer Veto: plastic scintillator strips (400 mm) -Target: 10,3 m 3 scintillator doped with 4.5g/l of Gd compound in an acrylic vessel (8 mm) -Catcher : 22,3 m 3 scintillator in an acrylic vessel (12 mm) Buffer: 110 m 3 of mineral oil in a stainless steel vessel (3 mm) viewed by 390 PMTs Inner Veto: 90m 3 of scintillator in a steel vessel equipped with 78 PMTs Veto Vessel (10mm) & Steel Shielding Detector Design New 4-region large detector concept

Muon Inner-VETO : LS PMT support structure: steel tank, optical insulation target/veto The detector design 7 m Shielding : steel 17 cm: >7 7 m -catcher : Extra-volume for -interaction 80% dodecane + 20% PXE + PPO + Bis-MSB -target : Volume for -interaction 80% dodecane + 20% PXE + PPO + Bis-MSB + 0.1% Gd n e p Gd ~ 8 MeV 511 keV e+e+ Non-scintillating buffer : Mineral Oil Isolate PMTs from target area Muon Outer-VETO : Scintillators Panels Acrylic vessels «hardware» definition of fiducial volume Improved background reduction

How much can we R = %(stat) 2.7%(syst) CHOOZ-far : 50,000/3 y CHOOZ-near: ~2.5x10 5 /3 y 2700Event rate 3-5 yearsFew monthsData taking period 0.5%2.8%Statistical error H/m H/m 3 Target composition 10.2 m m 3 Target volume Double-ChoozCHOOZ – Statistical error – Luminosity incerase L = t x P(GW) x Np Large detection volume & Long stable operation are necessary

Gd doped scintillator Solvent: 20% PXE – 80% Dodecane Gd loading: being 0.1% Gd loading of Gd-BDK (Beta Diketonate) Long term Stability promising LY ~7000 ph/MeV: 6 g/l PPO + 50 mg/l Bis-MSB Attenuation length: 5-10 m meters at 420 nm Radiopurity U: g/g - Th: g/g - K: g/g UV-VIS-IR scintillator transmission -All liquids are on site. MPI-K product and purify scintillators Gd(dpm) 3 for 2 years

e + Energy Systematic on Analysis/Selection n e p Gd e+e+ 1.5% syst. err. (Efficiency ~70% ) 2 layer design (no fiducial cut) Low BG PMT/Material Improve Veto detector Reduce # of cuts in Goal Double Chooz: Efficiency is INSENSITIVE to the energy scale error In total, 0.2~0.3% syst. err.: Better Energy calibration (depends on position) realize further reduction Neutron Energy t

Backgrounds Estimated with CHOOZ OFF data & Simulation ( represent CHOOZ data well) Spallation fast neutron μ capture Recoil p n capture on Gd Gd Recoil p n from capture μ μ N bkg = ~1.6 evts/day (Far) 2% of signal 0.7% syst err. =10~20evts/day (Near) 0.5% 0.2% syst err. Fast neutrons Gd ~ 8 MeV proton recoils μ ( 9 Li, 8 He) β-n γ PM + rocks + neutron-like event Correlated Accidentals Due to the different overburden, BG is not fully canceled. Better understand of BG reduces sys. errors. (To be measured within a few tens of percent If we can take ~a few weeks reactor OFF data.) Positron Energy spectrum

How much can we improve? Systematic error CHOOZDobule Chooz Reactor Cross section1.9%- Number of protons0.8%0.2% Detection efficiency1.5%0.5% Reactor power0.7%- Energy per fission0.6%- Total systematic error R = %(stat) 2.7%(syst) – Systematic errors – Double Chooz Goal in Phase 2 (Far+Near) Thanks to improved detector design and 2 detectors concept

Achievable sensitivity of sin 2 2θ 13 5 times better than current limit (5 year measurement) Achievable sensitivity of sin 2 2θ 13 (90%CL) m 2 atm = 2.5x10 -3 eV 2 (20% uncertainty by MINOS) CHOOZ: sin 2 2θ 13 < Far/Near ratio e + spectrum Spectrum Analysis is necessary for confidence

Status of construction/ Schedule in the future MaterialStatus of installation Steel shield Complete Inner veto tank Complete Inner veto PMT (8 78PMTs) Complete Buffer tank Complete Buffer tank PMT(10 390PMTs) Complete Gamma catcher and Target vessels Complete Close Lids Complete Electronics/DAQ installationOn going Liquid fillingSoon Far detector construction

Far site construction Lab cleaning Installation Veto and Veto-PMTsInstallation Buffertank February 2009 Overhaul CHOOZ Exp. Hall

PMT installation 400High performance low background 10" PMTs(Oil proof) (HAMAMATSU R7081MOD-ASSY) May 2009 Test Assembly Final test at Exp. site Installation to detector

PMT installation report July 2009 Buffer PMT complete

Acrylic vessel installation Acrylic vessels in lab Gamma Catcher installation Gamma Catcher transport Sept 2009 Acrylic vessels in buffer tank Oct 2009

Current status Construction Far Data Taking (Phase 1) In parallel, start filling of Liquid Scintillator to Acrylic Vessels, Buffer and Inner Veto. DAQ/Electronics installation will start in the Next week! DAQ/Electronics: Deadtime less Splitter(Installed), PMT HV supplies Trigger electronics 500MHz FADC, DAQ PCs Run control PCs Dec 2009 Lid closed Start Data taking!!!

Soon.. Construction Far Data Taking (Phase 1) Outer veto : Panels of strips of coextruded plastic scintillator with wavelength shifting fiber. Calibration: - Target fish-line & articulated arm - -catcher and buffer guide tubes - Embedded LEDs (Installed) Cstr. Near Data Taking (Phase 2) Data taking start. Then…. Improve data quality and reduce systematic errors.

Status of the Near site Tunnel (155 m), 12% slope Site engineering study completed Start excavation 2010 Site will be ready 2011 Neutrino fluxes: 2.5 x10 5 events in 3 years Depth: 120 m.w.e. ( flux: ~ 3-4 /m -2 s -1 ) Laboratory Open ramp (85 m), 14% slope Liquid storage 456m 160m 340m

Summary for Double Chooz The Double Chooz experiment –Double Chooz will be the first of a new generation of reactor neutrino experiments. It is the one of the best experimental concept to measure 13 The status of DoubleChooz Experiment –Detector Construction are close to the final stages. Installation of DAQ/Electronics starts in the next week. Filling of Liquid Scintillator follows. –We should observe the neutrino from reactor in this year! –Construction of the near site/detector will be started soon. Prospects for the future –First data taking expected to start in 2010 with far detector only sin 2 (2 13 ) < 0.06 in 1.5 year –From year 2011~, take data with the both near and far detectors sin 2 (2 13 ) < 0.03 in 3 years