2e268a0a1e6d32a4e8ce036dfd58f007.ppt
- Количество слайдов: 50
The Last Unknown Neutrino 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° What is e fraction of 3? Is there symmetry in neutrino mixing? Daya Bay DOE Briefing 0 ?
Measuring 13 with Reactor Neutrinos Search for 13 in oscillation experiment P ee Ue 3 detector 1 13 nuclear m 2 detector 2 m 2 ≈ reactor 13 23 ~1. 8 km ~ 0. 3 -0. 5 km Daya Bay DOE Briefing Daya Bay, China Distance (km) Pure measurement of 13.
Measuring 13 at Daya Bay 1. Search and discovery of 3 0 - key in understanding neutrino mixing and prospects for CP searches 2. Precise measurement of sin 22 3 13 and 23 are 2 of the 26 parameters of the SM, worthy of precision measurements resolves 23 degeneracy 3. Complimentarity with accelerator experiments together reactor + accelerator experiments (NOv. A, T 2 K) provide early indication of mass hierarchy and perhaps CP Reactor 3 experiment sets the scale for future accelerator-based oscillation measurements Daya Bay DOE Briefing Ref: hep-ex/0409028
Resolving the 23 Parameter Ambiguity Super-K, T 2 K disappearance 23 = 45± 9° NOv. A, T 2 K e appearance approximately, P[ e] acc appearance acc dis/appearance acc disappearance reactor Ref: hep-ph/0601258 Daya Bay DOE Briefing reactor + acc dis/appearance
13 from Reactor and Accelerator Experiments reactor ( e disappearance) - Clean measurement of 13 - No matter effects accelerator ( e appearance) mass hierarchy CP violation matter sin 22 13 is missing key parameter for any measurement of CP Daya Bay DOE Briefing
Future of Neutrino Oscillation Physics: Next 10 Years Reactor measurement of 13 Constraining CP in combined analysis Accelerator neutrino studies of e hep-ex/0409028 Daya Bay DOE Briefing
The Daya Bay Nuclear Power Facilities • Powerful facilities with total thermal power: 11. 6 GW (now) 17. 4 GW (2011) • Adjacent to mountain, easy to construct tunnels to underground labs with sufficient overburden to suppress cosmic rays Daya Bay DOE Briefing Daya Bay NPP: 2 2. 9 GWth Ling. Ao II NPP: 2 2. 9 GWth Ready by 2010 -2011 Ling. Ao NPP: 2 2. 9 GWth 1 GWth generates 2 × 1020 e per sec n
Far site 1600 m from Lingao 2000 m from Daya Overburden: 350 m Empty detectors are moved to underground halls through an access tunnel. Filled detectors can be swapped between the underground halls via the horizontal tunnels. Ling Ao Near 500 m from Lingao Overburden: 98 m 292 m (8% slope) 810 m Mid site ~1000 m from Daya Overburden: 208 m Ling Ao-ll NPP (under const. ) 230 m (15% slope) Ling Ao NPP Daya Bay Near 360 m from Daya Bay Overburden: 97 m Entrance portal Daya Bay NPP Total length: ~3000 m Daya Bay DOE Briefing
Geotechnical Survey far Topographical survey: produce high-resolution topographic maps Lingao near mid Daya near Daya Bay DOE Briefing Geophysical survey: probe subsurface structure mid Lingao near Borehole drilling
Findings of Geotechnical Survey • No active or large fault • Earthquake is infrequent • Rock structure: massive and blocky granite • Rock mass: most is slightly weathered or fresh • Groundwater: poor flow at the depth of the tunnel • Quality of rock mass: stable and hard US experts in geology and tunnel construction assist geotechnical survey: Chris Laughton Pat Dobson (FNAL) (LBL) Joe Wang Yanjun Sheng (LBL) (IGG) Good geotechnical conditions for tunnel construction Daya Bay DOE Briefing
The US should mount one multi-detector reactor experiment sensitive to edisappearance down to sin 22θ 13 ~ 0. 01. Daya Bay DOE Briefing
Sin 22 13 < 0. 01 Achieve high statistical precision: Utilize multiple reactor cores (4→ 6) effectively • At least 80 Tons at far site • Control Systematic errors: • Utilize multiple detectors at different baselines – measure RATIOS • Reactor power fluctuations – optimally combine ratios • Make detectors as IDENTICAL as possible Science Goals → Experiment Design → R&D Daya Bay DOE Briefing
Science Goals → Experiment Design → R&D Reduce and control systematic errors: • “Identical” detectors at multiple sites → detector design/construction, side-by-side comparisons • Detector performance - well-understood, stable → materials/construction, calibration/monitoring • Reduce radioactivity background → materials/construction, Gd-loaded scintillator • Reduce and measure cosmogenic backgrounds →shielding, muon veto and tracking, DAQ system • Swap detectors → horizontal tunnel system, locomotion equipment US R&D tasks focused on achieving these goals Daya Bay DOE Briefing
Antineutrino Detector First priority is to define interfaces with other systems: • Interface with cavern/tunnels • define lifting and support structures • define transport fixtures • understand detector environment (water, air) • Interface with calibration system • specify penetrations into detector • detector environment has significant influence on this interface buffer 20 t Gd-doped LS gamma catcher Antineutrino detector specifications: • Acrylic vessel thickness, transparency, compatibility with liquid scintillator • Surface reflectors, PMT configuration • Implications of moving detectors Daya Bay DOE Briefing
History of BNL R&D on Metal-loaded LS, M-LS § Dilute (<<1%) Gd in LS had been successfully used to detect neutrons in many relatively short-term nuclear-physics experiments. § However, prospects were dim to prepare high concentrations of M-LS (~10% Yb, In, or Nd) for years-long solar-neutrino (LENS) and experiments (SNOLab). § In 2002 -05, we at BNL developed new chemical methods to solve these problems, following approach from radiochemistry and nuclear-fuel reprocessing. § We successfully applied our methods to make suitable ~0. 1% Gd in PC (the LS) that avoided the chemical/optical degradation problems encountered in the Chooz and Palo Verde experiments. § Our current R&D is with a new LS, Linear Alkyl Benzene, LAB. § LAB is attractive alternative to PC. It is biodegradable, has Daya Bay DOE Briefing
Optical Attenuation of BNL Gd-LS, Stable so far for ~500 days Gd-LS under UV light (in 10 cm cells) Daya Bay DOE Briefing
Performance of Gd in PC and LAB Optical Spectra Light Output Spectra § Have ~1% Gd in 100% LAB and 100% PC. Will use ~0. 1% Gd in 13 experiment. § The LAB has lower optical absorption, longer attenuation length, better chemical and ESH properties. § LAB and PC have very similar light output efficiency Daya Bay DOE Briefing
Active Water Shield and Muon Tracker • Specifications – Two meters plus of purified water surrounding the neutrino detector modules to suppress ambient radioactivity background – Water pool equipped with PMTs to detect muons via their Cherenkov light with >95% efficiency – High efficiency (>95%) muon tracker; less than 0. 3% inefficiency when combined with the muon water Cherenkov – Good (ns) timing resolution to reduce accidentals due to ambient radioactivity background – Muon tracker can be deployed in water pool or outside water tank – Robust, good long-term stability Daya Bay DOE Briefing
Far Hall Detector Configuration Top vetoes Daya Bay DOE Briefing
Veto Configuration Daya Bay DOE Briefing
Muon Tracker • Scintillator strip muon tracker – Proven technology used in MINOS, OPERA and elsewhere • Not necessary to exceed performance of extant systems! – 10 cm x 1 cm x 7. 5 m plastic scintillator strips co-extruded with reflective Ti. O 2 on the outside – Scintillation light read out by wavelength shifting (wls) fibers embedded in strips – Fibers read out by multi-anode PMTs at both ends – High level of readout multiplexing possible since muon events have low occupancy – Two layers lining 5 sides of water pool or outside water tank provide good 2 -d tracking of through-going muons – Two or three layers on top to provide redundancy on stopping muons. – Total area of the muon tracker is about 5100 m 2 Daya Bay DOE Briefing
Opera target tracker Scintillator strips 6. 86 m x 26. 3 mm x 10. 6 mm read out by WLS fibers coupled to PMTs on both ends Daya Bay DOE Briefing
Opera tracker performance Four p. e. /MIP at the far end, so 2 -end requirement highly efficient Daya Bay DOE Briefing
Active Water Shield and Muon Tracker • Alternate/Backup muon tracker technologies – Resistive Plate Chambers: • Gas detectors read out by external pick-up strips (for water tank option only) • Least expensive option but efficiency susceptible to environmental parameters, especially pressure and gas purity – Liquid Scintillator Modules: • 50 cm x 5 cm x 7. 5 m liquid scintillator modules read out via wls at both ends by single-anode PMTs. • 5 cm thick modules allows rejection of ambient radioactivity background based on pulse height • One layer inside water pool or outside water tank and on top • Cheaper than plastic strips, but mechanically more complex Daya Bay DOE Briefing
RPC IHEP BESIII RPC 9698% Daya Bay DOE Briefing
LS Module cross section: or Performance scaled from NOv. A proposal ~10 p. e. at far end (7. 5 m) Daya Bay DOE Briefing 50 40 30 20 10 0
The Daya Bay Collaboration: China-Russia-US 20 institutions, 89 collaborators X. Guo, N. Wang, R. Wang Beijing Normal University, Beijing 100875, PRC L. Hou, B. Xing, Z. Zhou China Institute of Atomic Energy, Beijing 102413, PRC M. C. Chu, W. K. Ngai Chinese University of Hong Kong, PRC J. Cao, H. Chen, J. Fu, J. Li, X. Li, Y. Lu, Y. Ma, X. Meng, R. Wang, Y. Wang, Z. Xing, C. Yang, Z. Yao, J. Zhang, Z. Zhang, H. Zhuang, M. Guan, J. Liu, H. Lu, Y. Sun, Z. Wang, L. Wen, L. Zhan, W. Zhong Institute of High Energy Physics, Beijing 100039, PRC X. Li, Y. Xu, S. Jiang Nankai University, Tianjin 300071, PRC Y. Chen, H. Niu, L. Niu Shenzhen University, Shenzhen 518060, PRC S. Chen, G. Gong, B. Shao, M. Zhong, H. Gong, L. Liang, T. Xue Tsinghua University, Beijing 100084, PRC K. S. Cheng, J. K. C. Leung, C. S. J. Pun, T. Kwok, R. H. M. Tsang, H. H. C. Wong University of Hong Kong, PRC Z. Li, C. Zhou Zhongshan University, Guangzhou 510275, PRC Daya Bay DOE Briefing Yu. Gornushkin, R. Leitner, I. Nemchenok, A. Olchevski Joint Institute of Nuclear Research, Dubna, Russia V. N. Vyrodov Kurchatov Institute, Moscow, Russia B. Y. Hsiung National Taiwan University, Taipei, Taiwan, Republic of China M. Bishai, M. Diwan, D. Jaffe, J. Frank, R. L. Hahn, S. Kettell, L. Littenberg, K. Li, B. Viren, M. Yeh Brookhaven National Laboratory, Upton, NY 11973 -5000, USA R. D. Mc. Keown, C. Mauger, C. Jillings California Institute of Technology, Pasadena, CA 91125, USA K. Whisnant, B. L. Young Iowa State University, Ames, Iowa 50011, USA W. R. Edwards, K. Heeger, K. B. Luk University of California and Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA V. Ghazikhanian, H. Z. Huang, S. Trentalange, C. Whitten Jr. University of California, Los Angeles, CA 90095, USA M. Ispiryan, K. Lau, B. W. Mayes, L. Pinsky, G. Xu, L. Lebanowski University of Houston, Texas 77204, USA J. C. Peng University of Illinois, Urbana-Champaign, Illinois 61801, USA
Daya Bay DOE Briefing
Accomplishments at Collaboration Meeting • Bylaws were ratified by the Collaboration. • Institutional Board, with one representative from each Member Institution and two spokespersons, was established. • Executive Board was established: Y. Wang (China) C. Yang (China) M. C. Chu (Hong Kong) Y. Hsiung (Taiwan) A. Olshevski (Russia) K. B. Luk (US) R. Mc. Keown (US) • Scientific spokespersons were chosen: Y. Wang (China), K. B. Luk (US) • Project management in China and in the US were introduced. • Discussions on the management of the Construction Project. • Task forces were set up. Each task is led by at least one member from China and one from US. Daya Bay DOE Briefing
Joint US-China Task Forces International working groups with US-China co-leadership for main detector systems and R&D issues established at February collaboration meeting. 1. Antineutrino Detector Co-Chairs: S. Kettell (BNL, USA) Y. Wang (IHEP, China) 6. Offline Data Distribution and Processing Co-Chairs: J. Cao (IHEP) B. Viren (BNL) 2. Calibration Co-Chairs: R. D. Mc. Keown (Caltech, USA) X. Biao (CIAE, China) 7. Project Management and Integration Co-Chairs: B. Edwards (LBNL, USA) S. Kettell (BNL, USA) Y. Wang (IHEP, China) H. Zhuang (IHEP, China) 3. Communications Co-Chairs: J. Cao (IHEP, China) K. M. Heeger (LBNL, USA) W. Ngai (CUHK, Hong Kong) 4. Liquid Scintillator Co-Chairs: R. L. Hahn (BNL, USA) Z. Zhang (IHEP, China) I. Nemchenok (Dubna, Russia) 5. Muon Veto Co-Chairs: L. Littenberg (BNL, USA) K. Lau (Houston, USA) Y. Changgen (IHEP, China) Daya Bay DOE Briefing 8. Simulation Co-Chairs: J. Cao (IHEP, China) C. Jillings (Caltech, USA) 9. Tunneling and Civil Construction Lead: C. Yang (IHEP, China) US Consultant: C. Laughton (FNAL, USA)
R&D Plan and Priorities Daya Bay R&D Tasks 1) 2) 3) 4) Simulations Liquid Scintillator Antineutrino Detector Calibration 5) 6) 7) 8) Electronics Muon Veto Site Development Project Definition Primary R&D Goals: • Ensure a strong US contribution to the Daya Bay Experiment. • Match the schedule of Chinese R&D and design. Don’t let US slow project down! • Optimize US scope while minimizing cost. Full R&D funding in FY 06 (and FY 07): • Enable US input to experiment design. • Timely technology choices. • Early determination of project cost and schedule. • Finalize preparations for CD-1 in about six months. Daya Bay DOE Briefing
R&D Task #1 Simulations 1. 2. Quantitative guidance for US R&D and hardware efforts. Design analysis tools. Primary R&D Goals: • • • Short-term goal: quantitative guidance for US hardware efforts: • Muon veto and shield for suppression of fast-neutron, gamma-ray and cosmogenic backgrounds: efficiency, tracking accuracy. • Calibration/monitoring to maintain detection efficiency: develop program of source deployments. • Optics: sensitivity of detector response to acrylic thickness, PMT coverage/performance, scintillator transparency, surface reflectivity. Medium-term goals: • Design of analysis tools: event reconstruction, background identification. Support for Chinese R&D: • Electronics development (integration time, waveform vs. charge, trigger). US Role: • Strong US role in simulations is needed to support US project design. Consequences of reduced R&D funding in FY 06: • Possible delay in technology choices and project costing. Daya Bay DOE Briefing
Gd-Loaded Liquid Scintillator 1. 2. R&D Task #2 Require stable (~years) Gd-LS with high light yield, long attenuation length. Explore safer alternatives to pseudocumene, PC. US lead role, based on 3 years of R&D at BNL (ONP + LDRD) • Significant experience synthesizing metal-loaded PC, with high metal concentrations, 5 -10% (w/w) of In, Yb, Nd, for new solar and experiments. Primary R&D Goals: • • Results readily applied to make dilute ~0. 1% Gd in PC for Daya Bay. However, PC has drawbacks: • Low flashpoint, 48 o. C • Some health and environmental hazard (N. B. Borexino PC spill at LNGS) • Attacks acrylic plastic (detector vessel walls) Currently evaluating Gd-LS alternatives to PC. Is Crucial R&D: • Mixture of 20% PC and 80% dodecane • Very promising LS: Linear Alkyl Benzene, LAB, with high 130 o. C flashpoint, biodegradable (tons available, for industrial detergent production) Additional R&D support, including postdocs, are needed to exploit these key Gd-LS developments and meet the Daya Bay schedule. Consequences of reduced R&D funding in FY 06: • • Reduced opportunity for US leadership. Delays in scintillator choice, in producing LS for prototype, and in cost estimate Daya Bay DOE Briefing
R&D Task #3 Antineutrino Detector Measurement of sin 22 13 <0. 01 requires detector systems designed to minimize systematic uncertainties. 1. 2. Identical detector modules: • identical scintillator volumes, optical transparency. • facilitate calibration/monitoring system. Moveable detectors: • design detectors for identical performance at all sites. • engineer support and movement structures. • time critical due to close interface with tunnel/cavern design. Primary R&D Goals: • Mechanical design of central detector. • Design of transportation and installation systems for detectors. • Identify vendors for fabricating acrylic vessels. US Role: • Engineering and leadership experience at LBNL and BNL. Consequences of reduced R&D funding in FY 06: • Possible delay or additional risk in civil construction design contract. Daya Bay DOE Briefing Kam. LAND 2005
R&D Task #4 Development of Calibration and Monitoring Tools Precision measurement of sin 22 13 <0. 01 requires careful studies of detector systematic uncertainties. 1. • Calibration and monitoring of eight antineutrino detector modules: • need automated monitoring systems to regularly assess detector stability. Precise characterization of the detectors: • scintillator masses, attenuation lengths, H/C ratios, and Gd fractions. Primary R&D Goals: • Construct prototype calibration system: to be tested with prototype detector module in China. • Investigate instrumentation and techniques for the precise characterization of detectors and the liquid scintillator target. US Role — Leadership • US groups have extensive calibration experience in E 949, Kam. LAND and SNO. Consequences of reduced R&D funding in FY 06: • Reduced opportunity for US leadership. • Delay in firm cost estimate. Daya Bay DOE Briefing Kam. LAND 2005
R&D Task #5 Front-end and Trigger Electronics 1. 2. Front-end electronics • Measure charge/waveform of the PMT signal. • Determine the signal arrival times at the PMT’s. • Provide a fast energy sum signal for triggering. Trigger electronics • • Collect inverse beta-decay events with high efficiency. Collect events to monitor detector and measure backgrounds. Primary R&D Goals: • • • Refine functionality and specification of front-end electronics. Develop alternate design concepts for trigger electronics. Evaluation of prototypes fabricated in China. US Role: 1. 2. US groups have extensive electronics experience. Engineering resources at BNL and LBNL. Consequences of reduced R&D funding in FY 06: • Compromise US input to a key element of the experiment. Daya Bay DOE Briefing
R&D Task #6 Muon Veto/Tracker Understanding muon and spallation backgrounds: 1. High efficiency, redundant muon vetoes. 2. Tracking ability for systematic studies and event identification. Primary R&D Goals: • Evaluate candidate technologies for muon tracker: • Plastic scintillator strips • Resistive Plate Chambers • Liquid scintillator modules • Evaluate candidate technologies for muon veto: • Water pool Cherenkov • Water tank Cherenkov US Role — Leadership • US groups have extensive scintillator experience. Consequences of reduced R&D funding in FY 06: • Diminished R&D effort will delay technology choice and firm cost estimate. • Reduced opportunity for US leadership. Daya Bay DOE Briefing
R&D Task #7 Site Development 1. Analyze core samples: input for detailed civil construction design studies. 2. Define surface building and underground halls (space and infrastructure). 3. Define liquid scintillator purification and handling (space and infrastructure). Primary R&D Goals: • Define underground hall specifications in order to proceed to final civil design contract. • Interface between experiment design and hall design. US Role: • Engineering and physics design experience at LBNL and BNL. • Geology expertise at LBNL. Consequences of reduced R&D funding in FY 06: • Reduced input to civil design specification, possible delay or additional risk for civil construction. Daya Bay DOE Briefing Kam. LAND 2005
R&D Task #8 Project Definition 1. 2. 3. 4. Develop complete project scope and schedule (joint with China). Define US and Chinese deliverables (joint with China). Develop US cost and schedule ranges. Build US project team and organization. Primary R&D Goals: • Develop the US project scope, cost and schedule. • Coordinate with China on total project scope, cost and schedule. US Role: • US responsibility. Exploit project experience at LBNL and BNL. Consequences of reduced R&D funding: • Potentially problematic coordination with Chinese effort. • Delay in development of baseline project. • Less input on overall experiment design. • Risk of delay to Daya Bay experiment. Daya Bay DOE Briefing Kam. LAND 2005
Major US Project Scope Items • • Muon Tracker System (Veto Sys) Gd Loaded Liquid Scint. Calibration Systems PMT’s, Base’s & Control Readout Electronics & DAQ/Trig HW (partial) Acrylic Vessels (Central Detector) Detector Integration activities Project Management activities Daya Bay DOE Briefing
US Project Scope & Budget Targets Daya Bay DOE Briefing
Beyond Current Scope There are opportunities for the US in other areas also: * These are items in which the US could participate up to ~$1. 5 M Daya Bay DOE Briefing
Overall Project Schedule Daya Bay DOE Briefing
Project Development • Schedule/activities over next several months: Determine scale of detector for sizing halls – now – June Continue building strong US team – key people – now – summer Conceptual design, scale & technology choices – now – Aug Firm up US scope, schedule & cost range – July – Nov Write CDR, prepare for CD-1 – Aug – Nov Daya Bay DOE Briefing
What does the Daya-Bay Collaboration need? • Support – Schedule Lehman project reviews (fast-track) • • CD-1 - ~ November ’ 06 CD-2 - ~ September ’ 07 – Establish International Joint Agency Oversight Group • Decisions – Willing to schedule CD-1 prior to P 5 Committee report? – If Daya Bay is the precision reactor experiment – we anticipate accommodating additional collaborators • Funding – R&D funds for FY 06 (& 07) – Post-doc supplements to meet schedule – Forward funding of PMT procurement in FY 07? Daya Bay DOE Briefing
Supplemental Material • Overall project WBS • Preliminary civil construction schedule Daya Bay DOE Briefing
Overall Project WBS Daya Bay DOE Briefing
Prelim. Civil Construction Sched. Daya Bay DOE Briefing
ALT-US Project Scope & Budget Targets Daya Bay DOE Briefing
ALT-Beyond Current Scope There are opportunities for the US in other areas also: * These are items in which the US could participate up to ~$3. 5 M Daya Bay DOE Briefing