The Daya Bay Anti-neutrino Experiment On behalf on the Daya Bay Collaboration Jianglai Liu Shanghai Jiao Tong University KPS-CPS joint session, KPS annual meeting, Busan, 2011-10-20 1
13 in PMNS Matrix U PMNS 32 o cos12 sin12 sin12 cos12 0 0 cos 0 13 sin e 13 i 0 1 0 01 00 1 0 sin e 13 0 cos i 13 sin 0 cos 23 23 0 sin23 cos 23 45 o m 2 13 ~m 2 23 = 2.510-3 ev 2 : CP Violation Phase m 2 12 ~ 7.610-5 ev 2 2
Current Knowledge on 13 Upper limit from reactors Evidence from accelerators 3 non-zero from global analysis T2K collaboration 2011 Phys. Rev. Lett. 107 041801. Allowed Region sin 2 2 13 < 0.17 (90% c.l.) Fogli et al., arxiv:1106.6028 Chooz collaboration, Eur. Phys. J. C. 27 (331-374), 2003. MINOS collaboration 2011 arxiv:1108.0015v1 3
Lesson Learned in History: 3Discovery Phys. Lett. B 148: 387-394, 1984. Need definitive answer from other experiments! 13.6 m 18.3 m 4
Recent Excitement in Reactor Neutrino Disappearance A near-far relative measurement of reactor neutrino disappearance remains to be an unambiguous measurement of 13 Thierry Lasserre, TAUP 2011 2 2 P dis sin 2 sin (1.27m 13 2 13 L ) E 5
Daya Bay An Ideal Location Powerful reactor (top 5 in the world, 17.4GW th ) by mountains Daya Bay Daya Bay NPP 2.9GW2 LingAo NPP 2.9GW2 LingAo II NPP 2.9GW2 6
Daya Bay Collaboration Europe (3) JINR, Dubna, Russia Kurchatov Institute, Russia Charles University, Czech Republic North America (16) BNL, Caltech, LBNL, Iowa state, Illinois Inst. Tech., Princeton, RPI, Siena Coll. UC-Berkeley, UCLA, U- Cincinnati, U-Houston, U-Wisconsin, Virginia Tech., U-Illinois-Urbana- Champaign, W&M ~ 250 collaborators Asia (19) IHEP, Beijing Normal Univ., Chengdu UST, CGNPG, CIAE, Dongguan Univ. of Tech., Nanjing Univ.,Nankai Univ., Shenzhen Univ., Shandong Univ.,Shanghai Jiaotong Univ., Tsinghua Univ., USTC, Zhongshan Univ., Hong Kong Univ., Chinese Hong Kong Univ., Taiwan Univ., Chiao Tung Univ., National United Univ. 7
4 x 20 tons target mass at far site Daya Bay: Powerful reactor by mountains Far site (Hall 3) 1615 m from Ling Ao 1985 m from Daya Overburden: 350 m Ling Ao Near site (Hall 2) 481 m from Ling Ao 526 m from Ling Ao II Overburden: 112 m Water hall Liquid Scintillator hall entrance SAB Construction tunnel Ling Ao NPP, 2x2.9 GW Daya Bay Near site (Hall 1) 363 m from Daya Bay Overburden: 98 m Ling Ao-ll NPP 2x2.9 GW Total Tunnel length ~ 3000 m Daya Bay NPP, 2x2.9 GW
Experimental Hall Overview experimental hall PMTs RPCs water pool muon veto system Multiple identical anti-neutrino detector modules (2 @ Hall 1, 2 @ Hall 2, 4 @ Hall 3) Redundant muon detector: inner/outer water Cerenkov detectors + resistive plate chamber 9
Detection of Reactor Neutrinos Inverse Beta Decay e p n e Coincidence signal: detect Prompt: e + annihilation E v =KE e+ + 1.8 MeV Delayed: n capture on proton (2.2 MeV) or Gd (8 MeV) 10
Design of Anti-neutrino Detector (AD) Cylindrical 3-zone Structure Separated By Acrylic Vessels: I.Target: 0.1% Gd-loaded liquid scintillator, radius=half height= 1.55 m, 20 ton II. Gamma-catcher: liquid scintillator, 42.5 cm thick III. Buffer shielding: mineral oil, 48.8 cm thick Acyrlic vessel thickness: 1.5 cm (outer) and 1 cm (inner) 192 8 PMT s on circumference and reflective reflectors on top and bottom. 12% energy resolution at 1 MeV 11
Expected Neutrino Signals Prompt Energy Signal 1 MeV Monte Carlo Delayed Energy Signal Near sites ~700/day/detector Far site ~90/day/detector Monte Carlo 6 MeV 10 MeV 12
Projected Uncertainty stat = 0.18% (4 far detector modules) Projected Sys Per Module 13
Suppression of Major Systematic Uncertainty N N f n N N p, f p, n L L n f 2 f n P P survival survival ( E, L ( E, L f n ) ) sin 2 2 13 Number of Proton Ratio 0.3% Common Batch of liquid + precise flow & mass measurement Detector Efficiency Ratio 0.2% Calibrate out the near/far difference Identical Detectors Calibration, Calibration, Calibration! Side note: We blind true target masses, reactor power, and baselines to analyzer. 14
Calibration R=1.775 m R=0 R=1.35m Automated Calibration 3 sources for each z axis on a turntable: 68 Ge (0 KE e + = 20.511 MeV s) 241 Am- 13 C neutron source + 60 Co gamma source LED source for T 0, gain and relative QE 15
Projected Sensitivity 3 Years, 90% Confidence Level 1 Year Of Data Taking = 300 Days 16
Daya Bay in Action 17
AD Assembly SSV Bottom reflector 4m AV Top reflector PMT 3m AV SSV lid Leak check ACU 18
Interior of AD 19
Dry Run of the First Pair of AD Complete test of assembled ADs with final electronics, trigger and DAQ 20
Daya Bay Liquid Scintillator Monitoring of Gd-LS in underground storage tanks 0.1% Gd-LS in 5000L tank Gd-LS produced in 50, 4-ton batches but mixed in reservoir onsite to ensure identical detectors. Gd-LS stability for > 450 days. Daya Bay experiment uses 185 ton 0.1% gadolinium-loaded liquid scintillator (Gd-LS). Gd-TMHA + LAB + 3g/L PPO + 15mg/L bis-msb 21
AD Filling Requirement: precision mass, equal liquid level and tem., chemical compatibility, Liquid extracted from common 200 ton tanks Detectors are filled in pairs First two pairs of ADs have been filled 22
Hall 1 Water Pool Installation 23
Installed Detectors in Hall 1 24
Hall 1 Water Pool Filling in air in water Clear demonstration of the water shielding effect. 25
Filled Pool in Hall 1 26
Hall 1 Ready for Data 27
Hall 1 Live Time 28
Hall 1 Am-C Source at Center of AD Proton recoil spectrum in AD Neutroncapture energy spectrum Neutron capture time Preliminary 29
Hall 1 Muon Rate Preliminary Preliminary AD1 AD2 Inner Pool Outer pool ~16hours ~16hours 30
Hall 2 Installation 31
Hall 3 Getting Ready for AD 32
Status and Prospects Daya Bay has finished 4 out of 8 ADs AD5 and 6 assembly nearly finish AD7 and 8 completion in spring 2012 Hall 1 taking data since Aug 2011 Hall 2 being installed Hall 3 getting ready for installation Summer 2012, data taking with full experiment 33
Stay Tuned for the Excitement! 34