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大亚湾 核反应堆 中微子实验

ν. ν. 大亚湾 核反应堆 中微子实验. The Daya Bay Reactor Neutrino Experiment and ϑ 13. Manfred Jeitler HEPHY 19 October 2012. Material from Observation of Electron Anti-neutrino Disappearance at Daya Bay. Yifang Wang Institute of High Energy Physics CERN ， March 20, 2012

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大亚湾 核反应堆 中微子实验

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  1. ν

  2. ν 大亚湾 核反应堆 中微子实验 The Daya Bay Reactor Neutrino Experiment and ϑ13 Manfred Jeitler HEPHY 19 October 2012

  3. Material fromObservation of Electron Anti-neutrino Disappearance at Daya Bay YifangWang Instituteof High Energy Physics CERN，March 20, 2012 https://indico.cern.ch/conferenceDisplay.py?confId=181843 and from a private trip to China in July 2012 see also Invited Talk by YifangWang at VCI 2013 !

  4. ne nm ne nm Neutrinos & Neutrino Oscillation • Fundamental building blocks of matter: • Neutrino mass: the central issue of neutrino physics • Tiny mass but huge amount • Influence on Cosmology: evolution, large scale structure, … • Only evidence beyond the Standard Model • Neutrino oscillation: a great method to probe the mass Oscillation frequency Oscillation amplitude P(ne->nm) = sin2(2q)sin2(1.27Dm2L/E) Oscillation probability：

  5. Neutrino Oscillation P(ne nm) = sin2(2q)sin2(1.27Dm2L/E) neutrino energy Mixing angle (Amplitude) “baseline” numerical factor for using convenient units (km, GeV) m12 – m22 not (m1 – m2)2 !

  6. CKM Matrix and PMNS Matrix 1 0 0 0 1 0 0 0 1 1.0 0.2 0.0 0.2 1.0 0.0 0.0 0.0 1.0 CKM: (quarks)  1 1 0 0 1 1 0 0 1 0.8 0.5 -0.2 -0.3 0.7 0.6 0.4 -0.4 0.8 PMNS: (neutrinos) 

  7. CKM Matrix and PMNS Matrix • Cabibbo-Kobayashi-Maskawa • Pontecorvo-Maki-Nakagawa-Sakata

  8. ... and what about the masses? or maybe: inverted hierarchy normal hierarchy

  9. Daya Bay: for a New Type of Oscillation • Goal：search for a new oscillation q13 • Neutrino mixing matrix: n1 n2 n3 q12solar neutrino oscillation q13 ? Unknown mixing parameters: q13,d+ 2 Majorana phases q23atmospheric neutrino oscillation Need sizable q13 for the d measurement

  10. How to measure which type of oscillation? solar reactor atmospheric

  11. Two ways to measureq13 Reactor experiments: Pee  1 sin22q13sin2 (1.27Dm213L/E)  cos4q13sin22q12sin2 (1.27Dm212L/E) Long baseline accelerator experiments: Pme ≈ sin2q23sin22q13sin2(1.27Dm223L/E) + cos2q23sin22q12sin2(1.27Dm212L/E)  A(r)cos2q13sinq13sin(d) Small-amplitude oscillation due to 13 Large-amplitude oscillation due to 12 At reactors: • Clean signal, no cross talk with d and matter effects • Relatively cheap compared to accelerator based experiments • Provides the direction to the future of neutrino physics

  12. How to make neutrinos? • Accelerator: • Muon neutrinos (from pion decay: π  μ νμ) • expensive • Example: CNGS (Cern to Gran Sasso) • Reactor: • Fusion reactor • Sun • Electron neutrinos (p + p  d + e+ + νe) • Fission reactor • Nuclear power plants (such as Daya Bay) • Electron anti-neutrinos (n  p + e- + νe)

  13. ...o How to see neutrinos? ... without being blinded by the background?

  14. How to see neutrions? (from a fission reactor): original method of discoverers (Clyde L. Cowan and Frederick Reines, 1956):

  15. How to see neutrions? 向前一小步文明一大步 Xiàng qián yī xiǎo bù wénmíng yī dà bù Forward one small step, for civilization, a big step

  16. Daya Bay Experiment: Layout • Relative measurement to cancel Correlated Systematic Errors • 2 near sites, 1 far site • Multiple Antineutrino Detector modules at each site to reduce Uncorrelated Syst. Errors • Far: 4 modules，near: 2 modules • Multiple muon detectors to reduce veto efficiency uncertainties • Water Cherenkov： 2 layers • RPC： 4 layers at the top +telescopes Redundancy !!! • Cross check; Reduce errors by 1/N

  17. Underground Labs

  18. Anti-neutrino Detector (AD) • Three zones modular structure: • I. target: Gd-loaded scintillator • II. g-catcher: normal scintillator • III. buffer shielding: oil • 192 8” PMTs/module • Two optical reflectors at the top and the bottom, Photocathode coverage increased from 5.6% to 12% ~ 163 PE/MeV Target: 20 t, 1.6m g-catcher: 20t, 45cm Buffer: 40t, 45cm Total weight: ~110 t

  19. Neutrino Detection: Gd-loaded Liquid Scintillator t  28 ms(0.1% Gd) n + p  d + g (2.2 MeV) n + Gd  Gd* + g (8 MeV) Neutrino Event: coincidence intime, space and energy Neutrino energy: 10-40 keV 1.8 MeV: Threshold

  20. Muon Veto Detector • RPCs • 4 layers/module • 54 modules/near hall, 81 modules/far hall • 2 telescope modules/hall • Water Cerenkov detector • Two layers, separated by Tyvek/PE/Tyvek film • 288 8” PMTs for near halls; 384 8” PMTs for the far hall • Water processing • High purity de-ionized water in pools also for shielding • First stage water production in hall 4 • Local water re-circulation & purification • Two active cosmic-muon veto’s • Water Cerenkov: Eff.>97% • RPC Muon tracker: Eff. > 88%

  21. Two Antineutrino Detectors Installed in Hall 1

  22. Hall 1 (two Antineutrino Detectors) Started Operation on Aug. 15, 2011

  23. One AD installed in Hall 2 Physics Data Taking Started on Nov.5, 2011

  24. Three Antineutrino Detectors installed in Hall 3Physics Data Taking Started on Dec. 24, 2011

  25. Compare: High-tech, high-precision High-Energy Physics lab (Protvino, Russia)

  26. 中国科学院 大亚湾中微子实验站

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