1 / 38

Christopher White Illinois Institute of Technology and Lawrence Berkeley National Laboratory

Asian Reactor Anti-Neutrino Experiments DAYA BAY and RENO. Christopher White Illinois Institute of Technology and Lawrence Berkeley National Laboratory Neutrino 2008 - Christchurch, New Zealand 26 May 2008. Measuring si n 2 2 q 13 with reactors. Long-baseline accelerator exp.

ifeoma-fulton
Download Presentation

Christopher White Illinois Institute of Technology and Lawrence Berkeley National Laboratory

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. Measuring sin22q13 withreactors Long-baseline accelerator exp. Pme ≈sin2q23sin22q13sin2(1.27Dm223L/E) + cos2q23sin22q12sin2(1.27Dm212L/E)  A(r)cos2q13sinq13sin(d) Reactor experiment Pexsin22q13sin2 (1.27Dm213L/E) + cos4q13sin22q12sin2 (1.27Dm212L/E) • No ambiguity,independent of d and matter effect A() • Relatively cheap compared to accelerator-based experiments • Rapid deployment possible

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

  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) • Energy of eis given by: E Te+ + Tn + (mn - mp) + m e+  Te+ + 1.8 MeV 10-40 keV • 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.

  5. Daya Bay: Goal And Approach sin2213 = 0.01 3 4 5 6 7 8 9 10  energy (MeV) • 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.

  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. 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. Location of Daya Bay 55 km

  9. The Daya Bay Nuclear Power Complex Ling Ao NPP:22.9 GWth • 12th most powerful in the world (11.6 GWth) • One of the top five most powerful by 2011 (17.4 GWth) • 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 GWth Ready by 2010-2011 Daya Bay NPP: 22.9 GWth

  10. How To Measure 13 With a Reactor ? Disappearance probability Sin22q13 = 0.1 Dm231 = 2.5 x 10-3 eV2 Sin22q12 = 0.825 Dm221 = 8.2 x 10-5 eV2 far detector near detector • Since reactor eare low-energy, it is a disappearance experiment: Large-amplitude oscillation due to 12 Small-amplitude oscillation due to 13integrated over E • 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

  11. Baseline optimization and site selection m2 = 1.8 10-3 eV2 m2 = 2.4 10-3 eV2 m2 = 2.9 10-3 eV2 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 9Li Ideal case with a single reactor Daya Bay

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

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

  14. Antineutrino Detectors Calibration system Steel tank PMT Mineral oil Liquid Scint. 20-t Gd-LS 3.1m acrylic tank 4.0m acrylic tank ~ 12% / E1/2 • 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 5m 5m

  15. Systematic Uncertainty Control

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

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

  18. Shielding Antineutrino Detectors Neutron background vs thickness of water 0.30 0.25 Fast neutrons per day (far site) 0.20 2.5 m of water 2.5 m of water 0.15 0.10 0.05 1. 2. 0. water thickness (m) • 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

  19. 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)

  20. RPC Cover over Water Pool

  21. Electronics and Readout System

  22. Signal, Background, and Systematic • Summary of signal and background: • Summary of statistical and systematic budgets:

  23. Sensitivity of Daya Bay Far (80 t) 90% confidence level LA (40 t) DyB (40 t) 2 near + far (3 years) Sensitivity Year Goal: Sin22q13 < 0.01 • Use rate and spectral shape • input relative detector • syst. error of 0.38%/detector

  24. Summary • Daya Bay will reach a sensitivity of ≤ 0.01 for sin22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

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

  26. Google Satellite View of YeongGwang Site

  27. Comparison of Reactor Neutrino Experiments

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

  29. RENO Detector total ~460 tons

  30. Electronics • Use SK new electronics (will be ready in Sep., 2008)

  31. Mockup Detector Target + Gamma Catcher Acrylic Containers (PMMA: Polymethyl Methacrylate or Plexiglass) Buffer Stainless Steel Tank

  32. Systematic Errors

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

  34. Summary of Construction Status 2009 2006 2007 2008 Activities 12 12 12 12 3 3 3 3 6 6 6 6 9 9 9 9 Detector Design & Specification Geological Survey & Tunnel Design Detector Construction Excavation & Underground Facility Construction Detector Commissioning • 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.

  35. Summary Status Report - RENO • RENO is suitable for measuring q13 (sin2(2q13) > 0.02) • Geological survey and design of access tunnels & detector cavities are completed.Civil construction will begin in early June, 2008. • RENO is under construction phase. • Data taking is expected to start in early 2010. • TDR will be ready in June of 2008. • International collaborators are being invited.

  36. Thank You

More Related