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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 1

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 2 The Daya Bay Reactor Neutrino Experiment and 13 Manfred Jeitler HEPHY 19 October 2012

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 3 Material from Observation of Electron Anti-neutrino Disappearance at Daya Bay Yifang Wang Institute of 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 Yifang Wang at VCI 2013 !

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 4 Neutrinos & Neutrino Oscillation n Fundamental building blocks of matter: n 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 n Neutrino oscillation: a great method to probe the mass e e Oscillation probability P e sin sin 2 (1.27 m 2 L/E) Oscillation amplitude Oscillation frequency

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 5 Neutrino Oscillation P e sin sin 2 (1.27 m 2 L/E) Mixing angle (Amplitude) baseline m 1 2 m 2 2 not (m 1 m 2 ) 2 ! numerical factor for using convenient units (km, GeV) neutrino energy

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 6 CKM Matrix and PMNS Matrix 1 0 0 0 1 0 0 0 1 CKM: (quarks) 1 1 0 0 1 1 0 0 1 PMNS: (neutrinos) 1.0 0.2 0.0 0.2 1.0 0.0 0.0 0.0 1.0 0.8 0.5 -0.2 -0.3 0.7 0.6 0.4 -0.4 0.8

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 7 CKM Matrix and PMNS Matrix n Cabibbo-Kobayashi-Maskawa n Pontecorvo-Maki-Nakagawa-Sakata

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 8... and what about the masses? normal hierarchy inverted hierarchy or maybe:

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 9 Daya Bay: for a New Type of Oscillation Goal search for a new oscillation 13 n Neutrino mixing matrix: 1 2 3 12 solar neutrino oscillation 23 atmospheric neutrino oscillation 13 ? Unknown mixing parameters: 13, + 2 Majorana phases Need sizable 13 for the measurement

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 10 How to measure which type of oscillation? solar atmospheric reactor

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 11 Two ways to measure 13 Reactor experiments: P ee 1 sin 2 2 sin 2 (1.27 m 2 L/E) cos 4 sin 2 2 sin 2 (1.27 m 2 L/E) Long baseline accelerator experiments: P e sin 2 sin 2 2 sin 2 (1.27 m 2 L/E) + cos 2 sin 2 2 sin 2 (1.27 m 2 12 L/E) A( ) cos 2 13 sin sin( ) Small-amplitude oscillation due to 13 Large-amplitude oscillation due to 12 At reactors: Clean signal, no cross talk with and matter effects Relatively cheap compared to accelerator based experiments Provides the direction to the future of neutrino physics

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 12 How to make neutrinos? n Accelerator: Muon neutrinos (from pion decay: ) expensive Example: CNGS (Cern to Gran Sasso) n Reactor: n Fusion reactor Sun Electron neutrinos (p + p d + e + + e ) n Fission reactor Nuclear power plants (such as Daya Bay) Electron anti-neutrinos (n p + e - + e )

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 13...o 13 How to see neutrinos?... without being blinded by the background?

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 14 How to see neutrions? (from a fission reactor): original method of discoverers (Clyde L. Cowan and Frederick Reines, 1956):

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 15 How to see neutrions? Xing qin y xio b wnmng y d b Forward one small step, for civilization, a big step

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 16 Daya Bay Experiment: Layout n Relative measurement to cancel Correlated Systematic Errors 2 near sites, 1 far site n Multiple Antineutrino Detector modules at each site to reduce Uncorrelated Syst. Errors Far: 4 modules near: 2 modules n 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

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 17

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 18 Underground Labs Overburden MWE R Hz/m 2 E GeV D1,2 (m) L1,2 (m) L3,4 (m) EH12501.27573648571307 EH22650.95581348480528 EH38600.056137191215401548

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 19 Anti-neutrino Detector (AD) Target: 20 t, 1.6m -catcher: 20t, 45cm Buffer: 40t, 45cm Total weight: ~110 t Three zones modular structure: I. target: Gd-loaded scintillator -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

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 20 10-40 keV Neutrino energy: Neutrino Event: coincidence in time, space and energy Neutrino Detection: Gd-loaded Liquid Scintillator 1.8 MeV: Threshold s(0.1% Gd) n + p d + (2.2 MeV) n + Gd Gd* + (8 MeV)

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 21 Muon Veto Detector n RPCs 4 layers/module 54 modules/near hall, 81 modules/far hall 2 telescope modules/hall n Water Cerenkov detector Two layers, separated by Tyvek/PE/Tyvek film 288 8 PMTs for near halls; 384 8 PMTs for the far hall n 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 vetos Water Cerenkov: Eff.>97% RPC Muon tracker: Eff. > 88%

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 22 Two Antineutrino Detectors Installed in Hall 1

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 23 Hall 1 (two Antineutrino Detectors) Started Operation on Aug. 15, 2011

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 24 One AD installed in Hall 2 Physics Data Taking Started on Nov.5, 2011

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 25 Three Antineutrino Detectors installed in Hall 3 Physics Data Taking Started on Dec. 24, 2011

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 26

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 27 Compare: High-tech, high-precision High-Energy Physics lab (Protvino, Russia)

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 28

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 29

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 30

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 31

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 32

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 34

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 35

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 36

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 37

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 38

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 39

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 41

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 42

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 43

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 44

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 45

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 46

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 47

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 48

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 49

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 50

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 51

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 52

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 53

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 54 Event Signature and Backgrounds n Signature: Prompt: e +, 1-10 MeV, Delayed: n, 2.2 MeV@H, 8 MeV @ Gd Capture time: 28 s in 0.1% Gd-LS n Backgrounds Uncorrelated: random coincidence of n or nn from U/Th/K/Rn/Co in Liquid Scintillator, Stainless Steel Vessel, PMT, Rock, n from -n, -capture, -spallation in Liquid Scintillator, water & rock Correlated: Fast neutrons: prompt n scattering, delayed n capture 8 He/ 9 Li: prompt decay, delayed n capture Am-C source: prompt rays, delayed n capture -n: 13 C(,n) 16 O

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 55 Neutrino Event Selection n Pre-selection Reject Flashers Reject Triggers within (-2 s, 200 s) to a tagged water pool muon n Neutrino event selection Multiplicity cut Prompt-delayed pairs within a time interval of 200 s No triggers (E > 0.7MeV) before the prompt signal and after the delayed signal by 200 s Muon veto 1s after an Antineutrino-Detector shower muon 1ms after an Antineutrino-Detector muon 0.6ms after an Water Pool muon 0.7MeV < E prompt < 12.0MeV 6.0MeV < E delayed < 12.0MeV 1s < t e + -n < 200s

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 56 Backgrounds 8 He/ 9 Li Cosmic produced 9 Li/ 8 He in LS -decay + neutron emitter 8 He/ 9 Li ) = 171.7ms/257.2ms 8 He/ 9 Li, Br(n) = 12%/48%, 9 Li dominant Production rate follow E 0.74 power law n Measurement: Time-since-last-muon fit Improve the precision by reducing the muon rate: Select only muons with an energy deposit >1.8MeV within a [10us, 200us] window Issue: possible inefficiency of 9 Li Results w/ and w/o the reduction is studied 9 Li yield Error follows

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Manfred Jeitler Daya Bay Neutrino Experiment Hephy, 19 October 2012 57 Baseline n Survey: Methods: GPS, Total Station, laser tracker, level instruments, Results are compared with design values, and Power Plant coordinates Data processed by three independent software n Results: sum of all the differences less than 28 mm n Uncertainty of the fission center from reactor simulation: 2 cm horizontally 20 cm vertically n The combined baseline error is 35 mm, corresponding to a negligible reactor flux uncertainty (