1. Christopher White Illinois Institute of Technology and Lawrence Berkeley National Laboratory Neutrino 2008 - Christchurch, New Zealand 26 May 2008 Asian Reactor Anti-Neutrino Experiments DAYA BAY and RENO

2. 2 Measuring sin 2 2   with reactors No ambiguity,independent of  and matter effect A(  ) Relatively cheap compared to accelerator-based experiments Rapid deployment possible Long-baseline accelerator exp. 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(  ) Reactor experiment P ex  sin 2 2   sin 2 (1.27  m 2  L/E) + cos 4   sin 2 2   sin 2 (1.27  m 2  L/E)

3. 3 Reactor  e Fission processes in nuclear reactors produce a huge number of low-energy  e  e /MeV/fisso n Resultant  e spectrum known to ~1% 3 GW th generates 6 x 10 20  e per sec

4. 4 Detecting  in liquid scintillator: Inverse  -decay Reaction  e  p  e + + n (prompt)  + p  D +  (2.2 MeV) (delayed)  + Gd  Gd*  Gd +  ’s (8 MeV) (delayed) Time- and energy-tagged signal is a good tool to suppress background events. Detect inverse  -decay reaction in 0.1% Gd-doped liquid scintillator: 0.3b 50,000b Energy of  e is given by: E   T e+ + T n + (m n - m p ) + m e+  T e+ + 1.8 MeV 10-40 keV

5. 5 Daya Bay: Goal And Approach Utilize the Daya Bay nuclear power complex to: determine sin 2 2  13 with a sensitivity of 0.01 by measuring deficit in  e rate and spectral distortion. sin 2 2  13 = 0.01 23 4 5 6 7 8 9 10  energy (MeV)

6. 6 The Daya Bay Collaboration Europe (3) (9) JINR, Dubna, Russia Kurchatov Institute, Russia Charles University, Czech Republic North America (14)(~73) BNL, Caltech, 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 (18) (~125) IHEP, Beijing Normal Univ., Chengdu Univ. of Sci. and Tech., CGNPG, CIAE, Dongguan Polytech. Univ., Nanjing Univ., Nankai Univ., Shandong 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. ~ 207 collaborators

7. 7 How To Reach A Precision of 0.01 in Daya Bay? Increase statistics: –Use more powerful nuclear reactors –Utilize larger target mass, hence larger detectors Suppress background: –Go deeper underground to gain overburden for reducing cosmogenic background Reduce systematic uncertainties: –Reactor-related: Optimize baseline for best sensitivity and smaller residual reactor- related errors Near and far detectors to minimize reactor-related errors –Detector-related: Use “Identical” pairs of detectors to do relative measurement Comprehensive program in calibration/monitoring of detectors Interchange near and far detectors (optional)

8. 8 Location of Daya Bay 55 km

9. 9 Daya Bay NPP: 2  2.9 GW th The Daya Bay Nuclear Power Complex 12th most powerful in the world (11.6 GW th ) One of the top five most powerful by 2011 (17.4 GW th ) Adjacent to mountain, easy to construct tunnels to reach underground labs with sufficient overburden to suppress cosmic rays Ling Ao II NPP: 2  2.9 GW th Ready by 2010-2011 Ling Ao NPP: 2  2.9 GW th

10. 10 How To Measure  13 With a Reactor ? Go underground to reduce cosmogenic background Place near detector(s) close to reactor(s) to measure flux and spectrum of  e for normalization, hence reducing reactor-related systematic Position a far detector near the first oscillation maximum to get the highest sensitivity, and also be less affected by  12 Since reactor  e are low-energy, it is a disappearance experiment: Large-amplitude oscillation due to  12 Small-amplitude oscillation due to  13 integrated over E near detector far detector Sin 2   = 0.1  m 2 31 = 2.5 x 10 -3 eV 2 Sin 2   = 0.825  m 2 21 = 8.2 x 10 -5 eV 2 Disappearance probability

11. 11 Baseline optimization and site selection Inputs to the process: –Flux and energy spectrum of reactor antineutrino –Systematic uncertainties of reactors and detectors –Ambient background and uncertainties –Position-dependent rates and spectra of cosmogenic neutrons and 9 Li  m 2 = 1.8  10 -3 eV 2  m 2 = 2.4  10 -3 eV 2  m 2 = 2.9  10 -3 eV 2 Ideal case with a single reactor Daya Bay

12. 12 Daya Bay cores Ling Ao cores Ling Ao II cores Liquid Scintillator hall Entrance Construction tunnel Water hall Empty detectors: moved to underground halls via access tunnel. Filled detectors: transported between halls via horizontal tunnels. 295 m 810 m 465 m 900 m Daya Bay Near Overburden: 98 m Ling Ao Near Overburden: 112 m Far site Overburden: 355 m Daya Bay: Experimental Setup

13. 13 First Blast: Feb 19, 2008 Construction Tunnel Entrance Access Tunnel Entrance Moving forward … Daya Bay Is Moving Forward Quickly Groundbreaking Ceremony: Oct 13, 2007

14. 14 Antineutrino Detectors Three-zone cylindrical detector design –Target: 20 t (0.1% Gd LAB-based LS) –Gamma catcher: 20 t (LAB-based LS) –Buffer : 40 t (mineral oil) Low-background 8” PMT: 192 Reflectors at top and bottom 3.1m acrylic tank PMT 4.0m acrylic tank Steel tank Calibration system 20-t Gd-LS Liquid Scint. Mineral oil  12% / E 1/2 5m

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17. 17 Systematic Uncertainty Control

18. 18 AV Prototypes Under Construction… 3-m prototype in Taiwan 4-m prototype in the U.S.

19. 19 Automated Calibration System Major Prototype Test Results: Completed >20 years worth of cycling No liquid dripping problem Tested limit switch precision and reliability Each unit deploys 3 sources: 68 Ge, 252 Cf, LED MO overflow Calib. box elec. interface HKU MO clarity device MO fill monitor

20. 20 Shielding Antineutrino Detectors Detector modules enclosed by 2.5 m of water to shield energetic neutrons produced by cosmic-ray muons and gamma-rays from the surrounding rock 2.5 m of water Neutron background vs thickness of water Fast neutrons per day (far site) water thickness (m) 0.05 0.10 0.15 0.20 0.25 0.30 0. 1.2. 2.5 m of water

21. 21 Water Pool – Two Regions Divided by Tyvek into Inner and Outer regions Reflective Paint on ADs improves efficiency Calibration LEDs placed according to simulations 160 PMTs (Inner) 224 PMTs (Outer)

22. 22 RPC Cover over Water Pool

23. 23 Electronics and Readout System

24. 24 Signal, Background, and Systematic Summary of signal and background: Summary of statistical and systematic budgets: SourceUncertainty Reactor power0.13% Detector (per module)0.38% (baseline) 0.18% (goal) Signal statistics0.2%

25. 25 Sensitivity of Daya Bay DyB (40 t) LA (40 t) Far (80 t) Use rate and spectral shape Use rate and spectral shape input relative detector input relative detector syst. error of 0.38%/detector syst. error of 0.38%/detector 90% confidence level 2 near + far (3 years) Goal: Sin 2 2  13 < 0.01 Year Sensitivity

26. 26 Summary Daya Bay will reach a sensitivity of ≤ 0.01 for sin 2 2  13 Civil construction has begun Subsystem prototypes exist Long-lead orders initiated Daya Bay is moving forward: –Surface Assembly Building - Summer 2008 –DB Near Hall - installation activities begin early in 2009 –Assembly of first AD pair - Spring 2009 –Commission Daya Bay Hall by November 2009 –LA Near and Far Hall - installation activities begin late in 2009 –Data taking with all eight detectors in three halls by Dec. 2010

27. Current Status of RENO Slides courtesy of Dr. Soo-Bong Kim

28. 28 Google Satellite View of YeongGwang Site

29. 29 Comparison of Reactor Neutrino Experiments ExperimentsLocation Thermal Power (GW) Distances Near/Far (m) Depth Near/Far (mwe) Target Mass (tons) Double-CHOOZFrance8.7280/105060/30010/10 RENOKorea17.3290/1380120/45016/16 Daya BayChina11.6360(500)/1985(1613)260/91040  2/80

30. 30 Rock quality map Near detector site: - tunnel length : 110m - overburden height : 46.1m Far detector site: - tunnel length : 272m - overburden height : 168.1m

31. 31 RENO Detector Inner Diameter (cm) Inner Height (cm) Filled withMass (tons) Target Vessel 280320Gd(0.1%) + LS 16.5 Gamma catcher 400440LS30.0 Buffer tank540580Mineral oil64.4 Veto tank840880water352.6 total ~460 tons

32. 32 Electronics  Use SK new electronics (will be ready in Sep., 2008)

33. 33 Mockup Detector Target + Gamma Catcher Acrylic Containers (PMMA: Polymethyl Methacrylate or Plexiglass) TargetDiameter61 cm Height60 cm Gamma Catcher Diameter120 cm Height120 cm BufferDiameter220 cm Height220 cm Buffer Stainless Steel Tank

34. 34 Systematic Errors Systematic SourceCHOOZ (%)RENO (%) Reactor related absolute normalization Reactor antineutrino flux and cross section 1.9< 0.1 Reactor power0.7< 0.1 Energy released per fission0.6< 0.1 Number of protons in target H/C ratio0.80.2 Target mass0.3< 0.1 Detector Efficiency Positron energy0.80.2 Positron geode distance0.10.0 Neutron capture (H/Gd ratio)1.0< 0.1 Capture energy containment0.40.1 Neutron geode distance0.10.0 Neutron delay0.40.1 Positron-neutron distance0.30.0 Neutron multiplicity0.50.05 combined2.7< 0.6

35. 35 RENO Expected Sensitivity 10x better sensitivity than current limit New!! (full analysis)

36. 36 Summary of Construction Status  2007: Geological survey and tunnel design completed.  2008: Tunnel construction  Hamamatsu 10” PMTs are being considered - delivery starting 3/09  SK new electronics are adopted and ordered - 9/08  Steel/acrylic containers and mechanical structure ordered soon.  Liquid scintillator handling system is being designed.  Mock-up detector (~1/4 in length) will be built in June, 2008. Activities Detector Design & Specification Geological Survey & Tunnel Design Detector Construction Excavation & Underground Facility Construction Detector Commissioning 200620072008 2009 369 12 369 369 369

37. 37 Summary Status Report - RENO  RENO is suitable for measuring  13 (sin 2 (2  13 ) > 0.02)  RENO is under construction phase.  Geological survey and design of access tunnels & detector cavities are completed. Civil construction will begin in early June, 2008.  International collaborators are being invited.  TDR will be ready in June of 2008.  Data taking is expected to start in early 2010.

38. 38 Thank You