Скачать презентацию Daya Bay Experiment Steve Kettell BNL On Behalf Скачать презентацию Daya Bay Experiment Steve Kettell BNL On Behalf

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Daya Bay Experiment Steve Kettell BNL On Behalf of the Daya Bay Collaboration S. Daya Bay Experiment Steve Kettell BNL On Behalf of the Daya Bay Collaboration S. Kettell WIN 09 9/13/09

The Last Mixing Angle: 13 ? UMNSP Matrix Maki, Nakagawa, Sakata, Pontecorvo atmospheric, K The Last Mixing Angle: 13 ? UMNSP Matrix Maki, Nakagawa, Sakata, Pontecorvo atmospheric, K 2 K reactor and accelerator 23 = ~ 45° 13 = ? SNO, solar SK, Kam. LAND 12 ~ 32° 0 ? • What is e fraction of 3? • Is there symmetry in neutrino mixing? • Will we be able to observe CP violation? • Ue 3 is the gateway to leptonic CP violation. S. Kettell WIN 09 9/13/09 2

Detection of e Inverse -decay in Gd-doped liquid scintillator: e p e+ + n Detection of e Inverse -decay in Gd-doped liquid scintillator: e p e+ + n (prompt) 0. 3 b + p D + (2. 2 Me. V) 50 kb + Gd Gd* Gd + ’s(8 Me. V) (delayed) Prompt Energy Signal Delayed Energy Signal 1 Me. V 10 Me. V 6 Me. V n-p • Ee+ = [1, 8] Me. V • En (delayed) = [6, 10] Me. V. • tdelayed-tprompt = [0. 3, 200] s n-Gd • Calibrate with 68 Ge, neutron, and 60 Co • additional calibration with LED and spallation neutrons S. Kettell WIN 09 9/13/09 3

Measuring 13 at a Reactor • Precise measurement • No dependence on CP or Measuring 13 at a Reactor • Precise measurement • No dependence on CP or matter effects P ee Disappearance Probability detector 1 detector 2 nuclear reactor MO LS 13 Gd-LS Distance (km) ~1. 8 km ~ 0. 3 -0. 5 km S. Kettell WIN 09 9/13/09 • near detectors measure e flux and spectrum to reduce reactor-related systematic uncertainties • far detector at the oscillation max provides the highest sensitivity 4

Measurement Concept Measure ratio of interaction rates in multiple detectors νe near Measured Ratio Measurement Concept Measure ratio of interaction rates in multiple detectors νe near Measured Ratio of Rates Gd-LS Storage Tank Detector Mass Ratio, H/C mass measurement Near Far distance L ~ 1. 5 km Detector Efficiency Ratio far sin 22 13 calibration ± 0. 3% S. Kettell WIN 09 9/13/09 ± 0. 2% 5

Total tunnel length: ~2700 m 0 m 91 Far site 1600 m from Ling Total tunnel length: ~2700 m 0 m 91 Far site 1600 m from Ling Ao 2000 m from Daya Overburden: 350 m 2010 -11 570 m 730 m Water hall Ling Ao Near 500 m from Ling Ao Overburden: 98 m Ling Ao II: Ling Ao: 2 2. 9 GWth 1 GWth generates 2 × 1020 e /s Filling hall Daya Bay Near 360 m from Daya Bay Overburden: 97 m Total Power Now: 11. 6 GWth 2011: 17. 4 GWth Daya Bay NPP: S. 2. 9 GWth 2 Kettell WIN 09 9/13/09 6

Daya Bay Detectors • 8 Antineutrino detectors • 4 in far hall, 2 in Daya Bay Detectors • 8 Antineutrino detectors • 4 in far hall, 2 in each near hall • 20 t target mass per AD • Muon Veto system Ancillary Rooms - Gas - DAQ - Water S. Kettell WIN 09 9/13/09 7

Muon Veto System 1 m outer water veto 1. 5 m inner water veto Muon Veto System 1 m outer water veto 1. 5 m inner water veto Water Cerenkov (2 layers) 960 8” PMTs (3 pools) RPC AD Multiple muon detectors: § Water pool Cherenkov counter: inner/outer regions, 2. 5 m shield § RPC muon tracker § Combined efficiency (99. 5 0. 25)% S. Kettell WIN 09 9/13/09 8

Anti-neutrino Detector (AD) Design Calibration System I. III. q q Eight identical 3 -zone Anti-neutrino Detector (AD) Design Calibration System I. III. q q Eight identical 3 -zone detectors: Target: 20 t Gd-LS -catcher: 20 t LS Buffer shielding: 40 t mineral oil MO Top/bottom reflectors 192 8”PMT/module Reflectors LS Gd-LS 1. 55 m s. E/E = 12%/ E ~ 12% / E 1/2 1. 99 m PMT 2. 49 m Acrylic Total Weight = 110 t S. Kettell WIN 09 9/13/09 Vessels 5 m q 9

(Gd) Liquid Scintillator Daya Bay experiment uses 185 ton 0. 1% gadolinium-loaded liquid scintillator (Gd) Liquid Scintillator Daya Bay experiment uses 185 ton 0. 1% gadolinium-loaded liquid scintillator (Gd. LS). Gd-TMHA + LAB + 3 g/L PPO + 15 mg/L bis-MSB 500 L fluor-LAB Two 1000 L 0. 5% Gd. LAB 5000 L 0. 1% Gd. LS 0. 1% Gd-LS in 5000 L tank Gd-LS stability in 4 T test 4 -ton test batch production in March 2009. Gd-LS will be produced in multiple batches but mixed in reservoir on-site to ensure identical detectors. S. Kettell WIN 09 9/13/09 10

Daya Bay Background 840 backgrounds from beta-delayed neutron emission isotopes 8 He and 9 Daya Bay Background 840 backgrounds from beta-delayed neutron emission isotopes 8 He and 9 Li will have to be measured and subtracted 9 Li 4 near detectors ν signal S. Kettell WIN 09 9/13/09 11

Systematic Uncertainties CHOOZ: R=1. 01 2. 8%(stat) 2. 7%(syst), sin 22 13<0. 17 Detector-Related Systematic Uncertainties CHOOZ: R=1. 01 2. 8%(stat) 2. 7%(syst), sin 22 13<0. 17 Detector-Related Uncertainties Absolute measurement Relative measurement O(0. 2 -0. 3%) precision for relative measurement between detectors at near and far sites S. Kettell WIN 09 9/13/09 Ref: Daya Bay TDR 12

Sensitivity: sin 22θ 13 < 0. 01 @ 90% CL after 3 years of Sensitivity: sin 22θ 13 < 0. 01 @ 90% CL after 3 years of data taking Sensitivity in sin 22 13 (90%CL) Daya Bay Sensitivity 0. 05 0. 38% relative detector syst. uncertainty m 231 = 2. 5 10 3 e. V 2 0. 04 0. 03 0. 02 0. 01 0. 0 1 2 3 4 5 Number of years of data taking Source Reactor power Detector (per module) Signal statistics Uncertainty 0. 13% 0. 38% (baseline) 0. 2% Steps to Physics: • Dry-Run • near site operations S. Kettell WIN 09 9/13/09 • Full operations 13

Daya Bay Project Status • CD-0 (DOE Mission Need): 11/2005 Far hall • Daya Daya Bay Project Status • CD-0 (DOE Mission Need): 11/2005 Far hall • Daya Bay proposed at OHEP Briefing 4/2006 • Successful Physics Review 10/16/06 August 2009 • CD-1 site selection approved 9/2007 • Groundbreaking for civil construction 10/2007 • CD-2 Baseline approved 3/2008 • CD-3 b Construction start 8/2008 • Occupancy of SAB 3/2009 • Occupancy of first underground halls, fall 2009 • Expected start of first operations, summer 2010 • Full operations start, summer 2011 Ling Ao hall LS hall S. Kettell WIN 09 9/13/09 Daya Bay hall 14

Civil Construction Control Room Entrance Daya Bay Near Hall - July 09 Surface Assembly Civil Construction Control Room Entrance Daya Bay Near Hall - July 09 Surface Assembly Building S. Kettell WIN 09 9/13/09 15

Detector Assembly 0. 1% Gd-LS in 5000 -L tank 3 -m acrylic vessel in Detector Assembly 0. 1% Gd-LS in 5000 -L tank 3 -m acrylic vessel in Taiwan SS Vessel Reflector delivery to SAB S. Kettell WIN 09 9/13/09 4 -m vessel in the U. S. Prototype assembly in SAB 16

Summary and Conclusions The Daya Bay experiment is the most sensitive reactor θ 13 Summary and Conclusions The Daya Bay experiment is the most sensitive reactor θ 13 experiment under construction and is designed to measure sin 22θ 13 < 0. 01 at 90% CL with 3 years of data taking. • Daya Bay will use eight “identical” antineutrino detectors to achieve a relative detector systematic error < 0. 38%. The 3 -zone detector design allows the observation of the antineutrino signal without fiducial cuts. • Civil and detector construction are progressing well. Data taking at the near site is scheduled to begin in summer 2010 with 2 detectors, which will allow extensive studies of systematics. • The full experiment will begin in summer 2011. • Detectors are movable. Swapping can be considered after some running to further reduce systematic uncertainties but is not required to reach the baseline sensitivity. S. Kettell WIN 09 9/13/09 17

Daya Bay Collaboration Europe (3) (9) United States (15)(~89) BNL, Caltech, U. Cincinnati, George Daya Bay Collaboration Europe (3) (9) United States (15)(~89) BNL, Caltech, U. Cincinnati, George Mason U, LBNL, Iowa State U, Illinois Inst. Tech. , Princeton, RPI, UC-Berkeley, UCLA, U. of Houston, U. of Wisconsin, Virginia Tech. , U. of Illinois-Urbana-Champaign JINR, Dubna, Russia Kurchatov Institute, Russia Charles University, Czech Republic ~ 230 collaborators Asia (19) (~135) IHEP, Beijing Normal U. , Chengdu U. of Sci. and Tech. , CGNPG, CIAE, Dongguan Polytech. U. , Nanjing U. , Nankai U. , Shandong U. , Shanghai Jiaotong U. , Shenzhen U. , Tsinghua U. , USTC, Zhongshan U. , U. of Hong Kong, Chinese U. of Hong Kong, National Taiwan U. , National Chiao Tung U. , National United U. S. Kettell WIN 09 9/13/09 18

Backup S. Kettell WIN 09 9/13/09 19 Backup S. Kettell WIN 09 9/13/09 19

Phase-I, started in 2006, ended in Jan. 2007 S. Kettell WIN 09 9/13/09 20 Phase-I, started in 2006, ended in Jan. 2007 S. Kettell WIN 09 9/13/09 20

IHEP Prototype (0. 1% Gd-LS) Gd-TMHA complex synthesis Phase-II, filled with half-ton 0. 1% IHEP Prototype (0. 1% Gd-LS) Gd-TMHA complex synthesis Phase-II, filled with half-ton 0. 1% Gd-LS, started in Jan. 2007 and keep running until now. The prototype is also used for the FEE and Trigger boards testing. S. Kettell WIN 09 9/13/09 21

Calibration system Automated calibration system → routine weekly deployment of sources LED light sources Calibration system Automated calibration system → routine weekly deployment of sources LED light sources → monitoring optical properties • 68 Ge source • Am-13 C + 60 Co source • LED diffuser ball e+ and n radioactive sources (=fixed energy) → energy calibration automated calibration system S. Kettell WIN 09 9/13/09 22

Daya Bay Antineutrino Detectors 3 -Zone Design oil buffer (MO) thickness no position reconstruction, Daya Bay Antineutrino Detectors 3 -Zone Design oil buffer (MO) thickness no position reconstruction, no fiducial cut for event identification > 15 cm buffer between PMT and OAV MO Gd-LS (20 tons) LS Efficiency (%) gamma catcher (LS) thickness = 42. 3 cm det. efficiency > 91. 5% = 5 m (tunnel limitations) S. Kettell WIN 09 9/13/09 23

Detector Top/Bottom Reflectors specular reflectors consist of ESR® high reflectivity film on acrylic panels Detector Top/Bottom Reflectors specular reflectors consist of ESR® high reflectivity film on acrylic panels total p. e reflector flattens detector response without reflector with reflector z (cm) S. Kettell WIN 09 9/13/09 z (cm) 24 24

Antineutrino Detector Response Detector Uniformity along radial R direction Gd-LS boundary along vertical symmetry Antineutrino Detector Response Detector Uniformity along radial R direction Gd-LS boundary along vertical symmetry axis (zdirection) Gd-LS boundary - GEANT 4 -based simulations - idealized 3 -zone detector plus reflectors - developing realistic geometry in simulations S. Kettell WIN 09 9/13/09 25

Detector Calibration LED light sources → monitoring optical properties e+ and n radioactive sources Detector Calibration LED light sources → monitoring optical properties e+ and n radioactive sources (=fixed energy) → energy calibration automated calibration system tagged cosmogenic background (free) → fixed energy and time z(cm) automated calibration system → routine weekly deployment of sources R(cm) 68 Ge source Am-C + 60 Co source LED diffuser ball σ/E = 0. 5% per pixel requires: 1 day (near), 10 days (far) S. Kettell WIN 09 9/13/09 26

Energy calibration Prompt Energy Signal 1 Me. V + Delayed Energy Signal ν e Energy calibration Prompt Energy Signal 1 Me. V + Delayed Energy Signal ν e + p →e + n 8 Me. V 6 Me. V e+ threshold: stopped positron signal using 68 Ge source (2 x 0. 511 Me. V) e+ energy scale: 2. 2 Me. V neutron capture signal (n source, spallation) 1 Me. V cut for prompt positrons: >99%, uncertainty negligible 10 Me. V 6 Me. V threshold: n capture signals at 8 and 2. 2 Me. V (n source, spallation) 6 Me. V cut for delayed neutrons: 91. 5%, uncertainty 0. 22% assuming 1% energy uncertainty efficiency 98% S. Kettell WIN 09 9/13/09 efficiency 78% 27

Target mass measurement 200 -ton Gd-LS reservoir ISO Gd-LS weighing tank filling platform with Target mass measurement 200 -ton Gd-LS reservoir ISO Gd-LS weighing tank filling platform with clean room pump stations 20 -ton ISO tank LS Gd-LS detector MO load cell accuracy < 0. 02% Coriolis mass flowmeters < 0. 1% S. Kettell WIN 09 9/13/09 filling “pairs” of detectors 28

Nuclear reactors as antineutrino source • The observable antineutrino spectrum is the product of Nuclear reactors as antineutrino source • The observable antineutrino spectrum is the product of the flux and the cross section Arbitrary • Fission process in nuclear reactor produces huge number of low-energy antineutrino • A typical commercial reactor, with 3 GW thermal power, produces 6× 1020νe/s • Daya Bay reactors produce 11. 6 GWth now, 17. 4 GWth in 2011 From Bemporad, Gratta and Vogel Antineutrino spectrum x Flu S. Kettell WIN 09 9/13/09 s. S os ion ct e Cr 29

Proposed Reactor Experiments Krasnoyarsk, Russia Braidwood, USA Diablo Canyon, USA RENO, Korea sin 22 Proposed Reactor Experiments Krasnoyarsk, Russia Braidwood, USA Diablo Canyon, USA RENO, Korea sin 22 13~0. 03 Double Chooz, France sin 22 13~0. 03 KASKA, Japan Daya Bay, China sin 22 13~0. 01 8 proposals Angra, Brazil R&D phase 4 cancelled 4 in progress Advantages of Daya Bay: 1)very high antineutrino flux; 2) mountains to suppress cosmic-ray-induced background S. Kettell WIN 09 9/13/09 30