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The Double Chooz Experiment

The Double Chooz Experiment. Marcos Dracos IPHC-IN2P3 Strasbourg (for Double Chooz Experiment). Neutrino Oscillations and θ 13. atmospheric, accelerators θ 23 ~45 o. solar, reactors θ 12 ~34 o. CP violation can be observed if θ 13 >0.

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The Double Chooz Experiment

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  1. The Double Chooz Experiment Marcos Dracos IPHC-IN2P3 Strasbourg (for Double Chooz Experiment) M. Dracos IPHC/CNRS-UdS

  2. Neutrino Oscillations and θ13 atmospheric, accelerators θ23~45o solar, reactors θ12~34o CP violation can be observed if θ13>0 M. Dracos IPHC/CNRS-UdS

  3. What happened in the past about νe (or anti-νe) disappearance solar sector (θ12) In fact, on this plot θ13 has been neglected… M. Dracos IPHC/CNRS-UdS

  4. L/E L/E θ13 dependence the "good" L/E (~500) to place a detector for νe disappearance 2 ν oscillation approximation M. Dracos IPHC/CNRS-UdS

  5. νe νe νe νe νe νe Sin22θ13 and the Reactor Experiments sin22θ13 well known electron anti-neutrino isotropic source Eν ≤ 8 MeV Oscillations observed as a deficit of anti-neutrinos the position of the minimum is defined by Δm213 (~Δm223) 1.0 flux before oscillation observed here Probabilité νe Distance 1200 to 1800 meters significant reduction of systematic errors M. Dracos IPHC/CNRS-UdS

  6. Nuclear Reactors as a Neutrino Source (Bemporad, Gratta, Vogel) Observable ν spectrum unités arbitraires Cross section Flux • Nuclear reactors are a very intense source of νe using the β decay of fission fragments rich in neutrons. • Each fission liberates an energy of ~200 MeV and generates ~6 electron anti-neutrinos. For a typical commercial reactor (3 GW thermal power): • 3 GW ≈ 2×1021 MeV/s → 6×1020νe/s • The observable neutrino spectrum is given by the product of the flux and of the neutrino interaction cross section. • This spectrum has a maximum at ~3.7 MeV and a mean value of ~4 MeV (threshold at 1.8 MeV). M. Dracos IPHC/CNRS-UdS

  7. 511 keV Prompt 511 keV ~28 μs delayed Inverse β decay mode and neutrino detection In a pure scintillator the neutron will be captured by hydrogen: nH → Dγ (2.2 MeV) Very often the scintillator is doped with gadolinium that increase the neutron capture probability and liberate more γ's: nmGd → m+1Gdγ’s (8 MeV) M. Dracos IPHC/CNRS-UdS

  8. The 1st CHOOZ experiment (which gave the best θ13 limit) L/E~290 • Place: CHOOZ, Ardennes (France) • 2 cores: 2x4200 MW • shielding: 300 mwe • 5 tons of liquid scintillator (loaded with gadolinium) • <L> ~ 1 km M. Dracos IPHC/CNRS-UdS

  9. Results of CHOOZ experiment For these precision measurements the background knowledge is very important. accidental bkg compatible with 1 ⇒ no neutrino disappearance observed M. Dracos IPHC/CNRS-UdS

  10. νe →νx CHOOZ disappearance experiments sin2(2θ13) < 0.12 - 0.2 (90% C.L) R = 1.01 ± 2.8%(stat) ± 2.7%(syst) M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374 Present experimental picture on θ13 • Best present limit: CHOOZneutrino reactor experiment M. Dracos IPHC/CNRS-UdS

  11. νe νe,μ,τ near detector far detector. Double Chooz Experiment ~400 m 1050 m Two identical (improved compared to Chooz exp.) detectors reduce considerably the systematics M. Dracos IPHC/CNRS-UdS

  12. 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 M. Dracos IPHC/CNRS-UdS

  13. Site of Double Chooz 2 identical targets of 8.3t ν oscillation @1050m ν flux Normalisation @400m • PHASE 1 (2010-11) • - far detector only • - sin2(2θ13)<0.06 • (1,5 ans,90% C.L.) • PHASE 2 (2011-12) • - far + near • - sin2(2θ13)<0.03 • (3 ans,90% C.L.) 2 reactors-N4 2x4.27 GWth 1021νe/s M. Dracos IPHC/CNRS-UdS

  14. Aim of Double Chooz • Measure the mixing angle q13 • Limit: sin22θ13 < 0.03 @ 90% CL in 3 years • Necessary improvements (compared to 1st 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 Total uncertainty < 1% M. Dracos IPHC/CNRS-UdS

  15. n + Gd b/  ~ 8 MeV E > 1 MeV µ n β e- 8He  -n decay Gd n  ~ 8 MeV Background (key element) • Accidental: • gamma or beta events with E > 1 MeV • + • neutron capture by Gd, E ~ 8 MeV • radiopurity of detector components, • shielding against external radiation sources, • the "single"'s rate can be measured online • Correlated: • produced by muons and their secondaries • fast neutrons (produced by µ in the surrounding rock) • beta-neutron cascades (9Li, 8He): produced by the µ or n interactions with 12C • mean lifetime ~ (0.1 -1) s • shielding against cosmic rays, • active veto to recognise µ and n, • measurement of the background with the reactors off (if and when possible…). n Gd  ~ 8 MeV • Chooz: ~1/day • far: Nb < 0.6/day (90% CL) • near: Nb ~ 3.3/day (90% CL) • expected rate: • far: 1.4/day • near: 9/day M. Dracos IPHC/CNRS-UdS

  16. Double Chooz Expectations Sensitivity in sin22θ13 Chooz limit < 0.20Double Chooz Phase I < 0.06 Double Chooz Phase II < 0.03 sin22θ13 limit 2010 2011 2012 2013 2014 Hints (~1σ) for relatively large θ13 by combining all results G. Fogli et al., http://arxiv.org/abs/0905.3549 M. Dracos IPHC/CNRS-UdS

  17. DC Detector Calibration Glove-Box Outer Veto Scintillator panels Target  : 80% C12H26+ 20% PXE + PPO + Bis-MSB +0,1% Gd 10,3 m3  Catcher : 80% C12H26 + 20% PXE + PPO + Bis-MSB 22,6 m3 Non scintillating Buffer : Mineral oil 114 m3 7 m Buffer vessel & 390 10’’ PMTs : Stainless steel 3 mm Inner Muon Veto : Mineral oil + 78 8’’ PMTs 90 m3 Steel Shielding : 15 cm steel, All around 7 m M. Dracos IPHC/CNRS-UdS

  18. Far DC Detector construction(started on June 2008) October 2008 Demagnetized iron shielding (15 cm) M. Dracos IPHC/CNRS-UdS

  19. Far DC Detector construction Inner Veto installation (February 2009) Old 8" IMB PMTs (x78) operated at a gain 107 quartz fibres for calibration (LED's on the other side) M. Dracos IPHC/CNRS-UdS

  20. Far DC Detector construction Buffer tank installation (April 2009) Buffer 10" Hamamatsu PMT's x 390 (gain ~107) July 2009 PMT magnetic shielding and calibration fibre support M. Dracos IPHC/CNRS-UdS

  21. Far DC Detector construction Acrylic Gamma Catcher installation (August 2009) M. Dracos IPHC/CNRS-UdS

  22. To be installed soon DAQ and electronics • L1 Trigger board Outer Veto -F-ADC CAEN V1721 (500MHz & 8-bits) Liquid absorbance Liquid system (DFOS) M. Dracos IPHC/CNRS-UdS

  23. 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 M. Dracos IPHC/CNRS-UdS

  24. Future Projects to measure θ13 and δCP 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). 2011 M. Dracos IPHC/CNRS-UdS

  25. 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 • sin2(213) < 0.06 @ 90% C.L. and in absence of oscillation. • 2011-2013, phase II : both detectors • sin2(213) < 0.03 @90% C.L. M. Dracos IPHC/CNRS-UdS

  26. End M. Dracos IPHC/CNRS-UdS

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