The Double Chooz reactor neutrino experiment Inés Gil Botella 3rd CHIPP Neutrino Meeting November 17 -18, 2008 Overview The search for the θ13 mixing angle Neutrino measurements at reactor experiments The Double Chooz experiment Physics goals Experimental concept Detector design Present status Expected sensitivity and schedule Summary Inés Gil-Botella Page 2 Current knowledge on neutrino mixing parameters Best global limit on θ13 Experimental measurements arXiv:0808.2016 Global (90% CL) 2 sin θθθ13 ≤≤≤ 0.035 arXiv:0808.2016 2 θθθ13 , sign( ∆∆∆m 31 ), δδδ-CP ?? Inés Gil-Botella Page 3 The θθθ13 mixing angle The only mixing angle unknown CHOOZ Crucial for CP violation measurements in R = 1.01 ±±± 2.8%(stat) ±±± leptonic sector 2.7%(syst) Best experimental limit: CHOOZ reactor experiment νννe →→→ννν x νe νe (disappearance experiment) Pth = 8.4 GWth , L = 1.050 km, M = 5 t Overburden: 300 mwe 2 θ sin (2 13 ) < 0.12 - 0.2 (90% C.L) M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374 Inés Gil-Botella Page 4 Measuring θθθ13 : ννν-reactors vs super-beams Accelerator experiments : appearance experiments → 2 2 2 P( νµ νe) depends on sin (2θ13 ), sin (θ23 ), sign( ∆m 31 ), δCP phase Parameter degeneracies and correlations Matter effects sensitive Reactor ννν experiments are unique for: Unambiguous determination of θ13 no dependence on δCP No parameter degeneracies no dependence on mass hierarchy No matter effects 2 weak dependence on ∆m 12 Resolve θ23 degeneracy combined with accelerator experiments Reactor advantages with respect to accelerators : ►Pure θ 13 Both type of experiments ►Pure ν--, no flavor contamination e provide independent and ►ν flux known at few% complementary ► Smaller detectors (cheaper) information Inés Gil-Botella Page 5 Neutrino oscillations at nuclear reactors _ νννe disappearance searches ∆m 2 L ∆m 2 L P ≈1− sin 2 2θ sin 2 13 − cos4 θ sin 2 2θ sin 2 21 ee 13 E 13 12 E 4 ν 4 ν 2 Small deficit (= sin 2θθθ13 ) high precision is necessary Inés Gil-Botella Page 6 Antineutrino detection at nuclear reactors _ νννe detection: inverse beta decay + ve + p → n + e n + Gd → 8 MeV γ Prompt photons from e+ annihilation: EVIS ≈ Eν - (Mn-Mp) + m e Delayed photons from n capture: on H : ∆t ~200 µs, E~2 MeV on dedicated nuclei (Gd): ∆t ~30 µs, E ~8 MeV Inés Gil-Botella Page 7 Expected backgrounds at nuclear reactors Accidental events: e+ signal-like : radioactivity from n materials, PMTs, surrounding rock,… + Gd n signal-like : true neutrons from γγγ cosmic µ´s or gammas mimicking Eγγγ >~ 1 MeV ΣγΣγΣγ ~ 8 MeV neutrons Correlated events: n deposits energy Fast n : produced by cosmic µ´s Recoil-p (low energy) + Gd-capture n Gd Long-lived isotopes : 9Li & 8He ( β-n ΣγΣγΣγ ~ 8 MeV decay) Inés Gil-Botella Page 8 Complementarity with super-beams hep-ph/0601266 3σσσ discovery potential 3σσσ sensitivity (no signal) Inés Gil-Botella Page 9 Reactor neutrino experiments Double Chooz RENO Daya Bay Angra st 2 1 generation: sin (2 θ13 )~0.02-0.03 nd 2 2 generation: sin (2 θ13 ) 0.01 Inés Gil-Botella Page 10 Comparison between reactor experiments Thermal Depth Target Distances Near/Far Experiments Location Power Near/Far Mass (m) (GW) (mwe) (tons) Double Chooz France 8.7 400/1050 115/300 10/10 RENO Korea 16.4 290/1380 120/450 15/15 Daya Bay China 11.6 360(500)/1985(1613) 260/910 40 ×××2/80 Inés Gil-Botella Page 11 The Double Chooz experiment Inés Gil-Botella Page 12 Double Chooz goals Measure the θθθ13 mixing angle 2 Goal : sin 2θ13 < 0.03 @ 90% CL in 3 years Needed improvements : Increase statistics Suppress backgrounds More powerful reactors Improve detector design Longer exposure Better cosmic muon veto detectors Larger detector mass External shielding Reduce systematic uncertainties Near/Far detector comparison to minimize reactor errors Identical detectors to do relative measurements Detailed calibration program Non-proliferation studies (interest of IAEA) Use DC near detector as prototype for reactor monitoring Inés Gil-Botella Page 13 Double Chooz collaboration Spokesman: Hervé de Kerret (APC) France : APC Paris, CEA/Dapnia Saclay, Subatech Japan : HIT, Kobe, MUE, Niigata, TGU, TIT, TMU, Nantes, Strasbourg Tohoku Germany : Aachen, MPIK Heidelberg, TU München, Russia : RAS, RRC Kurchatov Institute EKU Tübingen, Hamburg USA : Alabama, ANL, Chicago, Columbia, Drexel, Spain : CIEMAT Madrid Illinois, Kansas, LLNL, LSU, Notre Dame, Sandia, Tennessee, UCD UK : Univ. Sussex Brazil : CBPF, UNICAMP Collaboration Meeting June 2008 Inés Gil-Botella Page 14 Double Chooz concept Near detector (400 m) Far detector (1050 m) 115 m.w.e. 300 m.w.e. ν ν ν ν ν ν ν 2 reactors - 8.5 GWth Far site already exists 2 identical detectors: ►Target: 2 x 8.3 t Comparison of neutrino rate & energy spectrum Civil work: ► 1 near lab is foreseen Chooz B nuclear power plant ► 1 farInés lab Gil-Botella is available Page 15 Ardennes, France Survival probability 2 “identical” detectors Rate comparison Spectral distortion ND Limit: FD Systematics Backgrounds Rate + shape information if θθθ13 not too small νννe νννe ? Far/Near energy bin ratio energy Far/Near Inés Gil-Botella Page 16 Far and near labs Far site (1050 m) Near site (400 m) ~ 500 evts/day ~ 70 evts/day Inés Gil-Botella Page 17 Detector design Outer veto Acrylic Target vessel (10.3 m 3 Gd-doped LS) Inner R =1.15 m H = 2.474 m t = 8 mm 7 m Acrylic Gamma catcher vessel Stainless steel (22.6 m 3 LS) Buffer (110 m 3 mineral oil) Inner R = 1.696 m Inner R = 2.758 m Inner H = 3.55 m Inner H = 5.674 m t = 12 mm t = 3 mm Inner VETO (90 m 3 LS) Shielding (steel) Inner R = 3.27 m Inner R = 3.471 m Inner H = 7 m Inner H = 6.840 m t = 10 mm t = 150 mm 7 m Inés Gil-Botella Page 18 Detector in the lab Electronics racks OTHER SYSTEMS OTHER SYSTEMS Calibration Systems Outer Muon Veto: Glove Box Plastic scintillator strips with X/Y meas Inés Gil-Botella Page 19 R&D activities and tests fADCs CAEN V1721 @ APC 1/5 mockup @ Saclay L1 Trigger board @ Aachen Magnetic tests @ CIEMAT Gd doped scintillator development @ MPIK Inés Gil-Botella Page 20 Current activities: Far lab integration Cleanliness + radiopurity measurements ongoing Civil engineering work completed Pit refurbished Access adapted Inés Gil-Botella Page 21 Current activities: Near lab preparation Neutrino Lab 85 m open air Site engineering study completed ramp (14%) Tender process for construction soon 155 m of Schedule: lab finished beginning 2010 gallery (12%) Neutrino Lab Liquid Handling and Storage Building ~12 m ~12 24 m >45 m rock overburden 85 m open air ramp (14%) 155 m of gallery (12%) Inés Gil-Botella Page 22 Current activities: Steel shield installation finished Assembly of each side of the bottom part Integration completed Demagnetization of steel shielding bars Inés Gil-Botella Connection of two bars Page 23 8m Current activities: Inner veto vessel installation in progress Inés Gil-Botella Page 24 Current activities: Inner detector components Scintillator production Mechanical vessels: Main components needed for both acrylics and buffer detectors have been delivered and Design completed checked Manufacturing is on going Scintillator hall ready Gd delivered Iso-tank for GC liquid Current activities: Tools for acrylics handling Target vessel tool COMPLETED!! Gamma-catcher vessel tool Inés Gil-Botella Page 26 Current activities: PMT production completed 10” R7081Low backgroundHamamatsu glass PMTs PMT geometry baseline (390 PMTs/detector) Being tested HV splitters PMT mechanical support & magnetic shield Production completed Inés Gil-Botella Production completed Page 27 Delivered Current activities: PMT testing and assembly PMT testing almost finished PMT assembly in progress Inés Gil-Botella Page 28 Current activities: Inner & Outer veto systems Inner Veto Outer Veto Tag efficiently cosmic ray muons & Redundancy for higher rejection external fast neutrons entering the power detector Full prototype built and tested 78 8” PMTs delivered and tested Inés Gil-Botella Page 29 Calibration systems Fish-line (Z-axis) Glove Box GC guide Tube Articulated Arm Embedded LED calibration system 385, 420, 470 nm Buffer guide Tube Inés Gil-Botella Page 30 Statistical and systematic errors @CHOOZ: R = 1.01 ±±± 2.8%(stat) ±±± 2.7%(syst) – Statistical error – Luminosity = ∆t x P(GW) x Np(target ) CHOOZ Double-Chooz Target volume 5.55 m 3 10.3 m 3 Target composition 6.77 10 28 H/m 3 6.55 10 28 H/m 3 Data taking period Few months 3-5 years CHOOZ-far : 40 000/3 y Event rate 2700 CHOOZ-near: ~1 10 6/3 y Statistical error 2.8% 0.5% – Systematic errors – Improve the detector design Two identical detectors: towards σrelative ~0.6% Careful backgrounds control: subtraction error<1% Inés Gil-Botella Page 31 Background rates hep-ex/0606025 (Old position) Inés Gil-Botella Page 32With new location N ν/2, N µ/3 Expected θθθ13 sensitivity 2 phases expected: FD 1. Far detector only : σσσsys =2.5% 10 x CHOOZ statistics sin 22θθθ <0.06 FD & ND θθ13 σσσsys =0.6% 2. Far + near detectors : shape analysis 2 sin 2θθθ13 <0.03 Double-Chooz can surpass the original CHOOZ result in 3 months (even with a single detector) Inés Gil-Botella Page 33 Schedule Proposal of the experiment ( hep-ex/0606025 ) Technical Design Report finished The first detector is being installed! Schedule: 2008-Summer 2009 : Far detector integration Summer 2009 : Far detector commissioning Beg. 2010 : Near lab completed 2010 : Near detector installation 2011 : Near and far detectors data taking Inés Gil-Botella Page 34 Summary Double Chooz is the first new generation reactor neutrino experiment using two identical detectors at different distances to measure θ13 Far detector installation has started! First data taking expected to start in 2009 with far detector: 2 sin 2θθθ13 < 0.06 in 1.5 years (90% CL) (if no oscillation) Data taking with far and near detectors in 2011: 2 sin 2θθθ13 < 0.03 in 3 years (90% CL) (if no oscillation) Inés Gil-Botella Page 35 Danke schön! Merci! BACKUP SLIDES Systematics Inés Gil-Botella Page 38 Relative normalization: analysis e+ @Chooz: 1.5% syst.