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The Daya Bay Experiment to Measure  13

The Daya Bay Experiment to Measure  13. Herbert Steiner UC Berkeley & LBNL On behalf of the Daya Bay Collaboration. Presented at the Erice School/Workshop on "Neutrinos in Cosmology,in Astro, in Particle and in Nuclear Physics” Erice/Sicily/Italy, September 21, 2009. Outline. • Overview

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The Daya Bay Experiment to Measure  13

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  1. The Daya Bay Experimentto Measure 13 Herbert Steiner UC Berkeley & LBNL On behalf of the Daya Bay Collaboration Presented at the Erice School/Workshop on "Neutrinos in Cosmology,in Astro, in Particle and in Nuclear Physics” Erice/Sicily/Italy, September 21, 2009

  2. Outline • Overview • Physics • Detector • Backgrounds • Calibration • Schedule

  3. The Daya Bay Collaboration Europe (3) (9) JINR, Dubna, Russia Kurchatov Institute, Russia Charles University, Czech Republic North America (15)(~89) BNL, Caltech, Cincinnati, George Mason Univ., LBNL, Iowa State Univ., Illinois Inst. Tech., Princeton, RPI, UC-Berkeley, UCLA, Univ. of Houston, Univ. of Wisconsin, Virginia Tech., Univ. of Illinois-Urbana-Champaign Asia (19) (~135) IHEP, Beijing Normal Univ., Chengdu Univ. of Sci. and Tech., CGNPG, CIAE, Dongguan Polytech. Univ., Nanjing Univ., Nankai Univ., Shandong Univ., Shanghai Jiaotong Univ., Shenzhen Univ., Tsinghua Univ., USTC, Zhongshan Univ., Univ. of Hong Kong, Chinese Univ. of Hong Kong, National Taiwan Univ., National Chiao Tung Univ., National United Univ. ~ 233 collaborators

  4. Location of the Daya Bay Nuclear Power Plant 45 km 55 km

  5. The Daya Bay Nuclear Power Plant 1 GWth generates 2 × 1020 e per sec • 12th most powerful in the world (11.6 GW) • Top five most powerful by 2011 (17.4 GW) • Adjacent to mountain, easy to construct • tunnels to reach underground labs with • sufficient overburden to suppress cosmic rays

  6. 4 x 20 tons target mass at far site Daya Bay Layout Far site 1615 m from Ling Ao 1985 m from Daya Overburden: 350 m Ling Ao Near site ~500 m from Ling Ao Overburden: 112 m 900 m 465 m Water hall Construction tunnel 810 m Filling hall entrance Daya Bay Near site 363 m from Daya Bay Overburden: 98 m Ling Ao-ll NPP (under construction) 22.9 GW in 2010 Ling Ao NPP, 22.9 GW 295 m Daya Bay NPP, 22.9 GW • Horizontal Tunnel • Total length 3200 m Total length: ~3100 m

  7. Topography Excellent overburden to reduce cosmogenic background Baselines (m):

  8. Tunnel Construction Status (July ‘09) Far Hall Ling Ao Hall Tunnel Entrance Daya Bay Near Hall Construction Tunnel

  9. Position Sensitivity

  10. Method How to measure 13? Measured ratio of Rates Proton Number Ratio Detector Efficiency Ratio sin2213 Filling Gd-LS and Mass measurement Calibration Systems

  11. sin2213 = 0.01 3 4 5 6 7 8 9 10  energy (MeV) Daya Bay: Goal and Approach • Utilize the Daya Bay nuclear power complex to: • determine sin2213 with a sensitivity of 0.01 • by measuring deficit in erate and spectral distortion.

  12. How to measure sin2213 to 0.01 Reduce systematic uncertainties: • Reactor-related: • Optimize baseline for best sensitivity and lowest residual errors • Near and far detectors to minimize reactor-related errors • Detector-related: • Use “Identical” pairs of detectors to do relative measurement • Fill all detectors with same batch of Gd-LS. • Comprehensive program in calibration/monitoring • Side-by-side calibration • Background-related • Go as deep as possible to reduce cosmic-induced backgrounds • Enough active and passive shielding • B/S ~0.4% Near • B/S ~0.2% Far

  13. Sensitivity in sin2213 (90%CL) 0.05 0.04 0.03 0 1 2 3 4 5 Number of years of data taking 0.02 0.01 0. Sensitivity of Daya Bay sin2213 < 0.01 @ 90% CL in 3 years of data taking 0.38% relative detector syst. uncertaintym231= 2.5  103 eV2

  14. e/MeV/fisson Resultant e spectrum known to ~1% Reactor e • Fission processes in nuclear reactors produce a huge number of low-energy e 3 GWthgenerates 6 x 1020 ne per sec

  15. e  p  e+ + n(prompt)  + p  D + (2.2 MeV) (delayed) • + Gd  Gd*  Gd + ’s(8 MeV) (delayed) • Energy of eis given by: E Te+ + Tn + (mn - mp) + m e+  Te+ + 1.8 MeV 10-40 keV Detecting e in liquid scintillator • Detect inverse -decay reaction in 0.1% Gd-doped liquid scintillator: 0.3b 50,000b • Time- and energy-tagged signal is a good • tool to suppress background events.

  16. Delayed Energy Signal Prompt Energy Signal 1 MeV 8 MeV 6 MeV 10 MeV • Ee+(“prompt”) [1,8] MeV • En-cap (“delayed”)  [6,10] MeV . Detection of e Inverse -decay in Gd-doped liquid scintillator: n-p n-Gd Coincidence of prompt positron and delayed neutron signals helps to suppress background events • tdelayed-tprompt [0.3,200] s

  17. Expected Antineutrino Rates (Per Day per Module) SiteRate DYB 840 LA 740 Far 90

  18. Systematic Uncertainty Control

  19. Sources of Uncertainty

  20. 740 Backgrounds

  21. Layout in DBY Hall

  22. Daya Bay Antineutrino Detector • 8 “identical”, 3-zone detectors calibration system νe + p → e+ + n Gd-doped liquid scintillator steeltank acrylic tanks liquid scintillator photomultipliers target mass: 20t per detector detector mass: ~ 110t photosensors: 192 PMTs energy resolution: 12%/√E mineral oil

  23. Gd-Liquid Scintillator Test Production Daya Bay experiment uses 200 ton 0.1% gadolinium-loaded liquid scintillator (Gd-LS).Gd-TMHA + LAB + 3g/L PPO + 15mg/L bis-MSB 500L fluor-LAB Two 1000L 0.5% Gd-LAB 5000L 0.1% Gd-LS 0.1% Gd-LS in 5000L tank Gd-LS stability in prototype 4-ton test batch production in April 2009. Gd-LS will be produced in multiple batches but mixed in reservoir on-site, to ensure identical detectors.

  24. Water Cherenkov Detector to Tag Muons

  25. Calibration

  26. Front End Electronics FAST ANALOG CIRCUIT for Analog Trigger SHAPING & ADC CIRCUIT for Charge Measurement INPUT STAGE THRESHOLD CIRCUIT for Multiplicity Trigger FEE ANALOG CIRCUITS

  27. Civil Construction Entrance Surface Assembly Bldg Inside tunnel Control Room

  28. Tunnel Construction Status Pool Excavation in DBY Hall - Aug 09 Main Tunnels Join - June 09

  29. Detector Assembly 3-m acrylic vessel in Taiwan Stainless steel tank in China 4-m vessel in the U.S. Stainless steel tank in SAB SS Tank delivery Delivery of 4m AV

  30. AD Components 4-meter acrylic vessel arrives Unpacked 4-m acrylic vessel Mounting of non-reflecting panels on ladder PMT Ladder

  31. AD Assembly

  32. Schedule • 2003-2007: Proposal, R&D, engineering design etc. • October 2007: Ground Breaking • March 2009: Surface Assembly Building occupancy • Summer 2010: Daya Bay Near Hall ready for data taking • Summer 2011: All near and far halls ready for data taking Three years’ data taking to reach full sensitivity.

  33. Thank You !

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