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Christian Buck, MPIK Heidelberg

The Double Chooz reactor neutrino experiment. Christian Buck, MPIK Heidelberg. LAUNCH 09 November, 11th 2009. Neutrino oscillations. sin 2 Θ 13. ν 3. sin 2 Θ 23. ν e. Δ m atm 2. ν μ. ν τ. sin 2 Θ 12. ν 2. Δ m sol 2. ν 1. Δ m sol 2 ~ 7.6∙10 -5 eV 2 , sin 2 (2 Θ 12 ) ~ 0.85

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Christian Buck, MPIK Heidelberg

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  1. The Double Chooz reactor neutrino experiment Christian Buck, MPIK Heidelberg LAUNCH 09 November, 11th 2009

  2. Neutrino oscillations sin2Θ13 ν3 sin2Θ23 νe Δmatm2 νμ ντ sin2Θ12 ν2 Δmsol2 ν1 Δmsol2 ~ 7.6∙10-5 eV2, sin2(2Θ12) ~ 0.85 Δmatm2 ~ 2.4∙10-3 eV2, sin2(2Θ23) ~ 1

  3. Why Double Chooz? • Improved knowledge of mixing matrix • Key experiment to unveil leptonic CP violation • Discovery potential: hint given by global analysis Fogli et al., arXiv:0905.3549 (2009) • Complementarity to beam experiments • Degeneracies + parameter correlations • Optimize future accelerator experiments • Discrimination power of 0νββ • Safeguard applications,…

  4. Reactor neutrino experiments 1956: First observation (Nobel Prize 1995) 1990s: Chooz, Palo Verde (sin22Θ13< 0.2) • Reactor neutrinos: • Pure νe - beam • Intense flux (~2% precision) • Detection: inverse β-decay • Energy: few MeV 2002: KamLand Δm12, Θ12

  5. Double Chooz collaboration • Spokesman: H. de Kerret (APC) • France: CEA Saclay, APC Paris, Subatech Nantes, IPHC Strasbourg • Germany: MPIK Heidelberg, TU München, EKU Tübingen, Universität Hamburg, RWTH Aachen • USA: Univ. of Alabama, Argonne Nat. Lab., Chicago, Drexel, Kansas State, LLNL, Notre Dame, Tennessee, Columbia Univ., Davis, MIT, Sandia • Spain: CIEMAT Madrid • Japan: Tohoku University, Kobe University, Tokyo Inst. of Tech., Niigata University, Tokyo Metropolitan University, Hiroshima Inst. of Tech. • England: University of Sussex • Russia: RAS Moskau, Kurchatov Institute • Brasil: CBPF Rio de Janeiro, UNICAMP

  6. The Double Chooz principle

  7. Dnear Dfar Survival probability Survival probability assuming sin2(2Θ13) = 0.2 for different Δm13 G. Mention (APC)

  8. Current proposals Double-Chooz RENO Daya bay Kaska Angra

  9. Neutrino signal n 235U prompt • pure e source • Eν~ MeV • Emin ~ 1.8 MeV • > 1020 /(s∙GW) Chooz:~ 7.4GWth e+ 511 keV 511 keV 236U e p n Gd β β  ~ 8 MeV Neutrino rates: • far: ~50/day • near: ~300/day delayed (30 µs) Target: Gadolinium loaded liquid scintillator

  10. Gd Background Accidentals β-n-cascades: 9Li,8He n Long lived! +  E ≥ 1 MeV  ~ 8 MeV fast neutrons Gd n Chooz data: far detector: ca. 1.4/day  ~ 8 MeV

  11. Detector Design • TARGET (2.3m) • Acrylic vessel (8mm) • 10,3 m3 LS (1 g/l Gd) • γ-catcher (0.55m) • Acrylic vessel (12mm) • 22,6 m3 LS • Buffer (1.05m) • Steel (3 mm) • 110 m3 oil 7m • Inner Veto (0.5m) • Steel (10 mm) • 80 m3 LS

  12. Calibration systems z-axis system (glove box) Target Articulated arm GC Guide tube / wire sources Buffer tube Buffer LED system / multi-wavelength

  13. Comparison with Chooz Best limit: CHOOZ sin2(2θ13) < 0.15 (90% CL) for m2atm = 2.5·10-3 eV2 R = 1.01  2.8%(stat)  2.7%(syst) Reactor Detector

  14. Sensitivity Sensitivity 2010 – 2015 (near detector starts < 2 y after far) for m2atm = 2.8·10-3 eV2 2010 Far detector filling early 2010!

  15. Far detector installation Lab cleaning Installation Veto and Veto-PMTs Installation Buffertank

  16. PMT installation

  17. Acrylic vessel installation Arrival Gamma Catcher on-site Acrylic vessels in lab Gamma Catcher transport Gamma Catcher installation

  18. Status October ‘09

  19. Status near detector • Site engineering study completed  excavate 2010 • r = 415 m (115 m w.e.) • Myons (Veto): 250 Hz near detector reactors Laboratory Open ramp (85 m), 14% Tunnel (155 m), 12% Liquid storage Data taking: 2011

  20. Scintillator development (MPIK) • Requirements: • Gd-solubility > 1 g/l • Stability (5 years) • Transparency • Material compatibility • Radiopurity • Target – Gamma catcher matching (optics + density) • Large scale (multi tons) PXE conc, Light yield PPO conc.

  21. Scintillator properties Event localization by pulse shape analysis Gamma Catcher candidates Events Transparency in ROI stable in 10 m range! Target Time [ns]

  22. Large scale production • All components (40 tons) delivered to MPIK • Purifications finalized, prepare for mixing • Scintillator production starts

  23. PMT activities at MPIK • Testing / Calibration • Assembly / Installation • Implementation of data in Double Chooz software • Current upgrade: full detector segment

  24. PMT calibration Calibration program: • HV scans • Single photon electron (P/V) • Transit time • Dark rate • Quantum efficiency

  25. Summary • Goal of Double Chooz reactor neutrino experiment: Determination of mixing angle Θ13 (sin2(2θ13)~ 0.03) • 2-detector concept to reduce systematical error • Detection via inverse β-decay in Gadolinium loaded liquid scintillator • Schedule: • Data taking far detector: Spring 2010 • Near detector: end of 2011 • MPIK: scintillators, PMTs, Analysis

  26. Θ13 and 0νββ M.Lindner, A.Merle, W.Rodejohann, Phys.Rev.D73:073012 (2006) Normal hierarchy: discrimination power of 0νββ-exp. depends on sin2(2Θ13) !

  27. Positron spectrum e+ spectrum Far/Near ratio Far Detetector Stat. Errors sin2(213)=0.12

  28. Sensitivity (rate vs shape)

  29. Robustness

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