The Double Chooz Experiment Marcos Dracos IPHCIN 2
The Double Chooz Experiment Marcos Dracos IPHC-IN 2 P 3 Strasbourg (for Double Chooz Experiment) Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 1
Neutrino Oscillations and θ 13 atmospheric, accelerators θ 23~45 o Sep. 2009 CP violation can be observed if θ 13>0 M. Dracos IPHC/CNRS-Ud. S solar, reactors θ 12~34 o 2
What happened in the past about νe (or anti-νe) disappearance solar sector (θ 12) In fact, on this plot θ 13 has been neglected… Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 3
θ 13 dependence the "good" L/E (~500) to place a detector for νe disappearance 2 ν oscillation approximation L/E Sep. 2009 M. Dracos IPHC/CNRS-Ud. S L/E 4
Sin 22θ 13 and the Reactor Experiments νe νe νe Probabilité νe 1. 0 well known electron antineutrino isotropic source Eν ≤ 8 Me. V Oscillations observed as a deficit of anti-neutrinos the position of the minimum is defined by Δm 213 (~Δm 223) sin 22θ 13 flux before oscillation observed here Distance 1200 to 1800 meters significant reduction of systematic errors Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 5
Nuclear Reactors as a Neutrino Source • Nuclear reactors are a very intense source of νe using the β decay of fission fragments rich in neutrons. 3 GW ≈ 2× 1021 Me. V/s → 6× 1020 ν e/s unités arbitraires • Each fission liberates an energy of ~200 Me. V and generates ~6 electron anti-neutrinos. For a typical commercial reactor (3 GW thermal power): Sep. 2009 M. Dracos IPHC/CNRS-Ud. S n x • This spectrum has a maximum at ~3. 7 Me. V and a mean value of ~4 Me. V (threshold at 1. 8 Me. V). Observable ν spectrum Flu • The observable neutrino spectrum is given by the product of the flux and of the neutrino interaction cross section. (Bemporad, Gratta, Vogel) s C s ro tio c se 6
Inverse β decay mode and neutrino detection 511 ke. V Prompt 511 ke. V ~28 μs In a pure scintillator the neutron will be captured by hydrogen: n H → D γ (2. 2 Me. V) Very often the scintillator is doped with gadolinium that increase the neutron capture probability and liberate more γ's: n m. Gd → m+1 Gd γ ’s (8 Me. V) delayed Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 7
The 1 st CHOOZ experiment (which gave the best θ 13 limit) L/E~290 Sep. 2009 M. Dracos IPHC/CNRS-Ud. S • Place: CHOOZ, Ardennes (France) • 2 cores: 2 x 4200 MW • shielding: 300 mwe • 5 tons of liquid scintillator (loaded with gadolinium) 8 • <L> ~ 1 km
Results of CHOOZ experiment For these precision measurements the background knowledge is very important. accidental bkg compatible with 1 ⇒ no neutrino disappearance observed Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 9
Present experimental picture on θ 13 CHOOZ R = 1. 01 ± 2. 8%(stat) ± 2. 7%(syst) • Best present limit: CHOOZ neutrino reactor experiment ν e →ν x disappearance experiments sin 2(2θ 13) < 0. 12 - 0. 2 (90% C. L) M. Apollonio et. al. , Eur. Phys. J. C 27 (2003) 331 -374 Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 10
far detector. near detector Double Chooz Experiment ν e, μ, τ νe ~400 m 1050 m Two identical (improved compared to Chooz exp. ) detectors reduce considerably the systematics Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 11
Double Chooz Collaboration • France: APC Paris, CEA/IRFU Saclay, Subatech Nantes, IPHC Strasbourg • • Germany: Aachen, MPIK Heidelberg, TU München, EKU Tübingen, Hamburg • • • Spain: CIEMAT Madrid • UK: Oxford, Sussex • Japan: HIT, Kobe, Niigata, TGU, TIT, TMU, Tohoku Russia: RAS, RRC Kurchatov Institute USA: Alabama, ANL, Chicago, Columbia, Drexel, Illinois, Kansas, LLNL, LSU, Notre Dame, Sandia, Tennessee, UCD Brazil: CBPF, UNICAMP ~180 physicists - 36 institutes/universities Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 12
Site of Double Chooz 2 identical targets of 8. 3 t ν flux Normalisation ν oscillation @1050 m @400 m §PHASE 1 (2010 -11) - far detector only - sin 2(2θ 13)<0. 06 (1, 5 ans, 90% C. L. ) §PHASE 2 (2011 -12) - far + near - sin 2(2θ 13)<0. 03 (3 ans, 90% C. L. ) Sep. 2009 2 reactors-N 4 2 x 4. 27 GWth 1021 ν e/s M. Dracos IPHC/CNRS-Ud. S 13
Aim of Double Chooz • Measure the mixing angle q 13 – Limit: sin 22θ 13 < 0. 03 @ 90% CL in 3 years • Necessary improvements (compared to 1 st exp. ): – Increase the statistics • Longer exposure • Larger detector – Reduce systematic uncertainties • Near/Far detector comparison to decrease reactor errors (neutrino flux monitoring) • Two identical detectors (same target, same cross sections) • Detailed detector calibration and monitoring – Reduce the background • Cosmic veto • Extra shielding CHOOZ Double Chooz 5. 55 m 3 10. 3 m 3 few months 3 -5 years Event rate 2700 Far: 4 104/3 y Near: 5 105/3 y Statistical uncertainty 2. 7% 0. 5% Reactor 2. 1% <0. 17% Detector 1. 64% <0. 28% Scintillator lifetime few % 0. 25% Analysis 1. 5% 0. 3% Systematic uncertainty 2. 7% <0. 6% Target volume Data taking period Total uncertainty < 1% Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 14
Background (key element) Accidental: gamma or beta events with E > 1 Me. V + neutron capture by Gd, E ~ 8 Me. V n / radiopurity of detector components, shielding against external radiation sources, the "single"'s rate can be measured online - E > 1 Me. V shielding against cosmic rays, active veto to recognise µ and n, measurement of the background with the reactors off (if and when possible…). Sep. 2009 Gd ~ 8 Me. V n e Correlated: -n decay produced by muons and their secondaries • fast neutrons (produced by µ in the surrounding rock) • beta-neutron cascades (9 Li, 8 He): produced by the µ or n interactions with 12 C mean lifetime ~ (0. 1 -1) s + 8 He n Gd ~ 8 Me. V Chooz: ~1/day • far: Nb < 0. 6/day (90% CL) • near: Nb ~ 3. 3/day (90% CL) expected rate: • far: 1. 4/day M. Dracos • IPHC/CNRS-Ud. S near: 9/day µ β n Gd ~ 8 Me. V 15
Double Chooz Expectations Sensitivity in sin 22θ 13 limit Chooz limit < 0. 20 Double Chooz Phase I < 0. 06 Double Chooz Phase II < 0. 03 2014 2013 2012 2011 2010 Hints (~1σ) for relatively large θ 13 by combining all results Sep. Fogli 2009 et al. , http: //arxiv. org/abs/0905. 3549 M. Dracos IPHC/CNRS-Ud. S G. 16
DC Detector Calibration Glove-Box Outer Veto Scintillator panels Target : 10, 3 m 3 80% C 12 H 26+ 20% PXE + PPO + Bis-MSB +0, 1% Gd Catcher : 22, 6 m 3 80% C 12 H 26 + 20% PXE + PPO + Bis-MSB 7 m Non scintillating Buffer : 114 m 3 Mineral oil Buffer vessel & 390 10’’ PMTs : Stainless steel 3 mm Inner Muon Veto : 90 m 3 Mineral oil + 78 8’’ PMTs Steel Shielding : 15 cm steel, All around Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 7 m 17
Far DC Detector construction (started on June 2008) October 2008 Demagnetized iron shielding (15 cm) Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 18
Far DC Detector construction Inner Veto installation (February 2009) Old 8" IMB PMTs (x 78) operated at a gain 107 Sep. 2009 M. Dracos IPHC/CNRS-Ud. S quartz fibres for calibration (LED's on the other side) 19
Far DC Detector construction Buffer tank installation (April 2009) July 2009 Sep. 2009 Buffer 10" Hamamatsu PMT's x 390 (gain ~107) PMT magnetic shielding and M. Dracos IPHC/CNRS-Ud. S calibration fibre support 20
Far DC Detector construction Acrylic Gamma Catcher installation (August 2009) Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 21
To be installed soon s c i n o Q A D a nd tr c le e eto V er - L 1 Trigger board -F-ADC CAEN V 1721 (500 MHz & 8 -bits) Out Liquid absorbance Liquid system (DFOS) Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 22
Far DC Detector construction • To do: • installation of the target vessel: Sep. 2009 • Target and Gamma catcher Chimney gluing: Sep. 2009 • Guide Tube installation: Sep. 2009 • installation of lid PMT's (IV+buffer): Oct. 2009 • Lid closing: Nov. 2009 • DAQ and electronics installation: Nov. -Jan. 2010 • Liquid system ready: Mar. 2010 • Filling: Mar. 2010 (reactor neutrinos observation) • Detector closing (Upper shielding): April 2010 • Glove box assembling: May 2010 • Outer veto assembling: June 2010 • Beginning of near detector construction: spring 2010 • Near detector ready: end 2011 Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 23
Future Projects to measure θ 13 and δCP 2011 Sep. 2009 M. Dracos IPHC/CNRS-Ud. S For negative or positive result, Double Chooz will give strong indication about the next neutrino facilities to build (important decisions are expected by 2012 -2013). 24
Conclusion § § Installation of far detector has started on June 08. Major detector parts are already installed. First reactor neutrinos observation by far detector by spring 2010. Beginning of near detector site excavation, construction and installation by spring 2010. § Near detector ready by end 2011. § Results: § 2010 -2011, phase I : far detector only § sin 2(2 13) < 0. 06 @ 90% C. L. and in absence of oscillation. § 2011 -2013, phase II : both detectors § sin 2(2 13) < 0. 03 @ 90% C. L. Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 25
End Sep. 2009 M. Dracos IPHC/CNRS-Ud. S 26
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