Jun Cao email@example.com Institute of High Energy Physics Reactor Neutrino Experiments Lepton-Photon 2007, Daegu, Aug. 13-18, 2007
Outline • Past Reactor Neutrino Experiments • Palo Verde • Chooz • KamLAND • Theta13 experiments • Angra • Daya Bay • Double Chooz • RENO • Search for neutrino magnetic moment • TEXONO • Summary
Past Reactor Neutrino Experiments Reactor anti-neutrino experiments have played a critical role in the 50-year-long history of neutrinos. • The first neutrino observation in 1956 by Reines and Cowan. • Determination of the upper limit of mixing angle theta13 to sin2213<0.17 (Chooz, Palo Verde) • The first observation of reactor anti-neutrino disappearance at KamLAND in 2003. Now reactor neutrino experiments become prominent again for measuring mixing angle 13 precisely.
Prompt signal Capture on H, or Gd, Cd, etc.Delayed signal Savannah River Experiment • The first neutrino observation in 1956 by Reines and Cowan. • Inverse beta decay in CdCl3 water solution coincidence of prompt and delayed signal • Liquid scintillator + PMTs • Underground • A modern experiment is still quite similar, except • Larger, better detector • Deeper underground, better passive and active shielding • Now we know how to load Gd into liquid scintillator
Reactor Neutrino Spectra • 235U, 239Pu, 241Pu beta spectra were measured at ILL. 238U spectrum is calculated theoretically. • Counting rate and spectra were verified by Bugey and Bugey-3 • Power fluctuation <1%, counting rate precision ~2% with burn-up evolution. • Spectra precision ~2% • Rate and spectra precision are less important for next theta13 experiments. Peak at 4 MeV
CHOOZ Baseline 1.05 km 1997-1998, France 8.5 GWth 300 mwe 5 ton 0.1% Gd-LS Bad Gd-LS R=1.012.8%(stat) 2.7%(syst), sin2213<0.17 Eur. Phys. J. C27, 331 (2003)
Palo Verde 1998-1999, US 11.6 GWth Segmented detector 12 ton 0.1% Gd-LS Shallow overburden 32 mwe Baseline 890m & 750m R=1.012.4%(stat) 5.3%(syst) 60%/year Palo Verde Gd-LS Chooz Gd-LS 1st year 12%, 2nd year 3% Phys.Rev.D64, 112001(2001)
KamLAND 2002-now, Japan 53 reactors, 80 GWth 1000 ton normal LS 2700 mwe Radioactivity fiducial cut, Energy threshold Baseline 180 km
KamLAND Phys.Rev.Lett. 94, 081801 (2005) R=0.6580.044(stat) 0.047(syst) The first observation of reactor anti-neutrino disappearance Confirmed antineutrino disappearance at 99.998% CL Excluded neutrino decay at 99.7% CL Excluded decoherence at 94% CL
Neutrino Oscillation Neutrino Mixing: PMNS Matrix Atmospheric, K2K, MINOS, T2K, etc.23 ~ 45º ReactorAccelerator13 < 12º SolarKamLAND12 ~ 30º Known: |Dm232|, sin22q23, Dm221, sin22q12 Unkown: sin22q13, dCP, Sign of Dm232 “We recommend, as a high priority, …, An expeditiously deployed multi-detector reactor experiment with sensitivity to e disappearance down to sin2213=0.01” ---- APS Neutrino Study, 2004
Precisely Measuring theta13 Major sources of uncertainties: • Reactor related ~2% • Detector related ~2% • Background subtraction Lessons from past experience: • Need near and far detectors • Chooz: Good Gd-LS • Palo Verde: Go deeper • KamLAND: No fiducial cut, lower threshold 4 MeV
Proposals for measuring 13 Krasnoyarsk, Russia Braidwood, USA RENO, Korea Double Chooz, France Diablo Canyon, USA KASKA, Japan Daya Bay, China Angra, Brazil • 8 proposals • 4 cancelled • 4 in progress
Angra Goal:sin2213 ~ 0.006 @ 90% CL. Site: Rio de Janeiro, Brazil • 30 researchers from 11 institutions. • Budget for Very Near (prototype) detector for Safeguards study approved by FINEP in March 2007 (~$0.5M) • High precision theta13 experiment in Angra around 2013? • Participation of the Brazilian group in Double Chooz experiment 4GW+1.8GW
LA: 40 ton Baseline: 500m Overburden: 112m Muon rate: 0.73Hz/m2 Far: 80 ton 1600m to LA, 1900m to DYB Overburden: 350m Muon rate: 0.04Hz/m2 0% slope 0% slope 0% slope Access portal DYB: 40 ton Baseline: 360m Overburden: 98m Muon rate: 1.2Hz/m2 8% slope Daya Bay Goal: sin22q13 < 0.01 @ 90% CL in 3 years. Site: Shen Zhen, China Goal: • Power Plant • 4 cores 11.6 GW • 6 cores 17.4 GW from 2011 • Three experimental halls • Multiple detectors at each site • Side-by-side calibration • Horizontal Tunnel • Total length 3200 m • Movable Detector • All detectors filled at the filling hall, w/ the same batch of Gd-LS, w/ a reference tank • Event Rate: • ~1200/day Near • ~350/day Far • Backgrounds • B/S ~0.4% Near • B/S ~0.2% Far
Daya Bay Detector • Eight 3-layer cylindrical anti-neutrino detectors, 5mx5m • Target mass 20 ton. Stable 0.1% Gd-LS by IHEP&BNL: [Gd+carboxylic]+LAB+fluor • Gamma catcher ~ 42cm, LAB+fluor • Oil Buffer ~ 50 cm, 192 8-in PMTs + reflective panels. Energy resolution ~12%/sqrt(E) • Water shield (2 layer water cherenkov) ~ 250 cm, ~2000 ton. 4 layer RPC at top. Oil Buffer Gamma Catcher RPC 20 t Gd-LS Antineutrino detector Water Cherenkov Reflective panel
200t Oil 200t LS 200t Gd-LS Hall 5: LS mixing and filling Civil Construction Underground Filling in hall 5 Significantly reduce detector systematic uncertainties. • Same batch of Gd-LS and LS H/Gd ratio, H/C ratio, light properties • A reference tank with load cell to fill all detectors Target mass 0.1-0.2% Site Survey, bore hole 2005.5-2006.6 Conceptual Design 2006.6-2006.8 Preliminary Design 2007.1-2007.3 Engineering Design 2007.3-2007.7 Civil Bidding 2007.8-2007.9 Start civil construction 2007.9 Complete civil construction 2009.6
Daya Bay Status • ~180 collaborators, 34 institutes from China (Taiwan, Hong Kong), Czech, Russia, and United States. • All funding from China (all civil and ~50% detector) is secured. • Passed US DOE physics review (2006.10) and CD1 review (2007.4).R&D funding approved.CD2/3a review scheduled in 2007.11.Detector construction funding (~50% detector) expected shortly after CD2/3a . • Funding from Taiwan, Czech, Russia is secured. Schedule Start Tunnel Construction ……………… 2007. 09 Surface Assembly Building ready ……… 2008. 06 DB Near Hall civil complete …………… 2008. 07 DB Near Site ready to take data ………. 2009. 06 LA Near Site ready to take data ……… 2010. 05 All Sites Ready to take Data…………… 2010. 10 90% C.L.
Daya Bay R&D • A 2-layer prototype running at IHEP for 1.5 years. Outer detector: 2mx2m, Inner acrylic vessel: 1mx1m. • Phase-I with 800 liters normal LS for 1 year. • Phase-II with 800 liters 0.1% Gd-LS has been running for 7 months. • A 2-layer prototypes is under construction in Hong Kong. (underground) • 3-m and 4-m Acrylic Vessel prototype will be completed before 2007.11 • All critical detector components are being prototyped, e.g. water system, reflectors, RPC chamber, electronics, PMT base and seal, etc. Stability monitoring of 800-L 0.1% Gd-LS in IHEP prototype. No visible attenuation length degradation. Prototype with 45 8” PMTs
Double Chooz Goal: sin22q13 < 0.03 @ 90% CL in 3 years Near detector (~280 m) ~80 m.w.e. Far detector (1050 m) 300 m.w.e. ν ν ν ν ν ν ν • 2 reactors - 8.5 GWth • 2 identical detectors: • Target: 2 x 8.3 t • Comparison of neutrino rate & energy spectrum • Civil work: • 1 near lab is foreseen • 1 far lab is available Far site already exists Ardennes, France
Double Chooz Detector • 3-layer cylindrical detector • Target mass 8.3 ton. Stable Gd-LS by Heidelberg: [Gd+Beta-Dikotonates]+[20% PXE+80% dodecane]+fluor • Gamma catcher ~ 54cm, normal LS • Oil Buffer ~ 100 cm, 390 10-in PMTs • Veto ~ 50 cm, shielding 15cm
Double Chooz Status ~100 scientists, 32 institutions from Brazil, France, Germany, Japan, Russia, Spain, UK, and US. The experiment has been approved by most of the respective Scientific Councils • Proposal of the experiment (hep-ex/0606025) • Technical Design Report almost finished • Funding has been established in Europe • NSF groups in US funded • Japan and US DOE groups pending • The experiment is moving forward • Schedule: • 2007-2008: Detector construction and integration • 2008: Far detector data taking starts, sin22q13 < 0.06 (90% CL) • 2010: Near detector starts 90% C.L. m2atm = 2.8 10-3 eV2
RENO YongGwang NPP, Korea 6 cores, 16.4 GW Goal: sin22q13 ~ 0.02 @ 90% CL in 3 years
RENO Detector • Target 15-t 0.1% Gd-LS, [Gd+CBX or BDK] + [20%PC+80% dodecane] + fluor, R&D by INR/IPCE group • Gamma Catcher ~60 cm • Oil Buffer ~70 cm, 537 8-in PMTs, 7.7%/sqrt(E) • Water veto ~1 m, PMT number undetermined.
RENO Status • Experiment site usage has been approved. • Geological survey completed in 2007.05 • Issue tunnel construction contract in 2007.10 • Detector Construction begin in 2007.10 • Data taking expected to start in early 2010. 43 collaborators, 13 institutes from Korea, Russia Project was approved for funding in 2005 with 10M USD.
RENO R&D 140-L gamma catcher • Small prototype running • Working on “mock-up” detector • Gd-LS R&D 4-L Gd-LS
TEXONO • TEXONO Collaboration – Academia Sinica-based and run, with groups from China, Turkey & India, close partnership with KIMS group in Korea. • Facilities – Kuo-Sheng Reactor Neutrino Laboratory in Taiwan; YangYang Underground Laboratory in South Korea. • Program – Low Energy Neutrino and Astroparticle (Dark Matter) Physics.Neutrino Magnetic Moments, Neutrino Radiative Decays, Axions Y2L
Reactor Neutrino Interaction Cross-Sections quality Detector requirements mass Bkg level at O(10 keV)~ 1 counts / kg-keV-day On-Going Data Taking & Analysis [CsI(Tl)] : • SM s(ne) • T > 2 MeV • R&D (ULEGe) : • Coh. (nN) • T < 1 keV Results (HPGe): • mn(ne) • T ~ 1-100 keV
TEXONO 2007 Highlights Improved Limits in Neutrino Magnetic Moments (PRL-03, PRD-07) mn(ne)< 7.4 X 10-11mB @ 90% CL • Bounds on neutrino radiative decays. • Reactor Axion (PRD-07): • Improved laboratory limits axion mass 102-106 eV • Exclude DFSZ/KSVZ Models for axion mass 104-106 eV • On-Going – measurements of neutrino-electron scattering cross-sections (i.e. sin2w at MeV) • Future – develop 100 eV threshold + 1 kg mass detector for • First observation of neutrino-nucleus coherent scattering • Dark matter searches for WIMP-mass less then 10 GeV • Improvement of neutrino magnetic moment sensitivities
Summary • Precisely measuring 13 is one of the highest priority in neutrino oscillation study. Sensitivity to sin2213 < 0.01 is achievable based on experiences of past reactor neutrino experiments. • Four theta13 experiments are in progress. Three of them project similar timeline, full operation starting in 2010. Double Chooz will get 0.06 before 2010 using a single far detector. • Limit on neutrino magnetic moment is improved to be < 7.4 X 10-11B by TEXONO. Many interesting physics topics can be carried out at very near neutrino scattering experiment.