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This presentation discusses the Daya Bay Reactor Neutrino Experiment and its significance in probing neutrino oscillation, a fundamental aspect of neutrino physics. The experiment aims to measure the unknown mixing parameter, q13, and determine the type of oscillation occurring. It compares reactor experiments and long-baseline accelerator experiments as methods to measure q13, highlighting the advantages of reactor experiments. The experiment setup, including the Antineutrino Detector modules and the Muon Veto Detectors, is explained, along with the detection process and data taking. The importance of the experiment in advancing neutrino physics is emphasized.
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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
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 !
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:
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 !
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)
CKM Matrix and PMNS Matrix • Cabibbo-Kobayashi-Maskawa • Pontecorvo-Maki-Nakagawa-Sakata
... and what about the masses? or maybe: inverted hierarchy normal hierarchy
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
How to measure which type of oscillation? solar reactor atmospheric
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)cos2q13sinq13sin(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
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)
...o How to see neutrinos? ... without being blinded by the background?
How to see neutrions? (from a fission reactor): original method of discoverers (Clyde L. Cowan and Frederick Reines, 1956):
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
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
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
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
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%
Hall 1 (two Antineutrino Detectors) Started Operation on Aug. 15, 2011
One AD installed in Hall 2 Physics Data Taking Started on Nov.5, 2011
Three Antineutrino Detectors installed in Hall 3Physics Data Taking Started on Dec. 24, 2011
Compare: High-tech, high-precision High-Energy Physics lab (Protvino, Russia)
中国科学院 大亚湾中微子实验站