Research Program of TEXONO Collaboration on Neutrino & Astroparticle Physics Highlights of Recent Neutrino Results TEXONO Overview Kuo-Sheng Program Results on Neutrino Magnetic Moment R & D Program Scenario of Further Contacts/Collaboration Henry T. Wong / 王子敬 Academia Sinica / 中央研究院 @ Czech-Taiwan Workshop on M/HEP March 2003
Experimental Neutrino Physics ……
Nobel Prize in Physics (2002) 50% for n astrophys. : Ray. Davis Jr. (U. Penn) : “Classic” Chlorine Expt. Masatoshi Koshiba 小柴昌俊 (U. Tokyo) : Kamiokande & SuperK Citations leave room for future prizes on n physics !!! 50% to Riccardo Giacconi, in X-Ray Astronomy
Super-Kamionkande ※ Water Cerenkov detector: 5k tons, viewed by 11,000+ =50 cm PMTs in 1000 m underground site in central Japan ※ Physics: solar n, atmospheric n , long baseline accelerator n, proton decays .. ※ Accidents (PMTs imploded) Nov 01, 50% PMT data again end of 02 !!!
Solar Neutrinos : The Sun IS Burning !!!! & Detection Deficit Atmospheric Neutrinos: Up-Down Asymmetry & Deficit
KEK-SuperK (K2K) Accelerator n Flight path 250 km
Sudbury Neutrino Observatory (SNO) ※ Heavy Water Cerenkov detector: 1k ton, shielded by 7k ton of water viewed by 9456 PMTs located 2000 m underground in Canada. ※ Physics: Solar n …
Detect correct amount of solar n-active ; but deficit in ne (also Cl, Ga, diff. E) (also SK) ( 5s effect )
KamLAND Long Baseline Reactor n (sensitive to 20% of world’s reactors !) ave. flight path of 160 km 1 kton liquid scintillator in old Kamiokande site probe “LMA” for solar n historical results only 5 years from approved !!!!
Detects deficit of reactor ne-bar ; agrees LMA of solar neutrinos
Dm2 – : Summary 2002 PDG 2000: SK atm. n SNO solar n
K2K : Consistent Checks to atm. n KamLAND : picks LMA for solar n
TEXONO Overview Goals : Program: Neutrino and Astroparticle Physics Starting phase: 1st particle physics expt in Taiwan Build up a Qualified Group 1st big research Coll. % Taiwan & China Kuo-Sheng Reactor Neutrino Lab. ※ reactor : high flux of low energy electron anti-neutrinos ※ mn0 anomalous n properties & interactions ※ n’s strange & full of surprises study/constraint new regime wherever possible experimentally R&D Projects diversified program ※ reactor program as base ※ explore various future scenarios Program:
TEXONO* Collaboration W.C. Chang¶, C.P. Chen, K.C. Cheng, H.C. Hsu, F.S. Lee, S.C. Lee, S.T. Lin, D.S. Su, P.K. Teng, W.S. Tse¶, H.T.K. Wong†, C.S. Wu, S.C. Wu Academia Sinica, Taipei, Taiwan W.P. Lai Chung Kuo Institute of Technology, Taipei, Taiwan C.H. Hu, J.M. Huang, W.S. Kuo, T.R. Yeh Institute of Nuclear Energy Research, Lungtan, Taiwan H.B. Li, M.Z. Wang¶ National Taiwan University, Taipei, Taiwan J.H. Chao, J.H. Liang National Tsing Hua University, Hsinchu, Taiwan Z.M. Fang, R.F. Su Nuclear Power Station II, Kuosheng, Taiwan M. He, S. Jiang, L. Hou, Y.H. Liu, H.Q. Tang, B. Xin, Z.Y. Zhou¶ Institute of Atomic Energy, Beijing, China J. Li†, Y. Liu, Z.P. Mao, J. Nie, J.F. Qiu, H.Y. Sheng, P.L. Wang, X.W. Wang, Q. Yue, D.X. Zhao, J.W. Zhao, P.P. Zhao, S.Q. Zhao, B.A. Zhuang Institute of High Energy Physics, Beijing, China Z.S. Liu, Z.Y. Zhang Institute of Radiation Protection, Taiyuan, China T.Y. Chen Nanjing University, Nanjing, China J.P. Cheng, D.Z. Liu Tsing Hua University, Beijing, China C.Y. Chang, G.C.C. Chang† University of Maryland, Maryland, U.S.A. † Co-Prinicipal Investigators ¶ Project Leaders Ph.D. Students *Taiwan EXperiement On NeutrinO Home Page @ http://hepmail.phys.sinica.edu.tw/~texono/ HISTORY Initiate : Chang Chung-Yung 1996 First Collab. Meeting/Official Start : October 1997 First Paper : October 1998 KS Reactor Experiment Installation : June 2000 First Ph.D. : Liu Yan , July 2000 First Physics Data Taking : June 2001. First Physics Result : December 2002 Under discussions : cosmic ray physics group, U. Puebla, Mexico
Kuo-Sheng Nuclear Power Plant KS NPS-II : 2 cores X 2.9 GW KS n Lab: 28 m from core#1
Kuo-Sheng Neutrino Laboratory High flux of ne (also ….. ne ) Modular Design : independent detector, electronics, shielding high-Z target, large re Improved detector performance: good energy & spatial resolution, low threshold, a/g separation Elaborate electronics+DAQ+control sys. complete record of pulse shape + timing info. Elaborate Shieldings radon purge & 4p cosmic veto Configuration: Modest yet Unique Flexible Design: Allows different detectors conf. for different physics
Kuo Sheng Reactor Neutrino Laboratory Front Gate Front View (cosmic vetos, shieldings, control room …..) Inner Target Volume
ULB-HPGe + Anti-Comptons KS Expt. : Period I Configuration Period I : June 01 – April 02 (60 days OFF) Shielding & Veto [one side] ULB-HPGe + Anti-Comptons CsI(Tl) Array (46 kg)
KS Expt: Period I Detectors ULB-HPGe [1 kg] CsI(Tl) [46 kg] FADC Readout [16 ch., 20 MHz, 8 bit] Multi-Disks Array [600 Gb]
mn with Reactor ne mn Experimental Probe: parametrize possible niL njR + g vertices both i = j “diagonal” & i j “transition” moments Experimental Probe: Study ne + e- nX + e- Focus on low recoil energy ※ sm T–1 ※ decouples SM “background” [ ……… LE reactor f(ne) not accurately known] Look for Excess in Reactor ON/OFF Neutrino Radiative Decay (Gn): sm & Gn related: same vertices – real g for Gn Electron Recoil Spectra
PDG Limit : 1.5 X 10-10 mB (from SK spectral shape) an allowed solution for the solar neutrino data (before KamLAND)
KS/P1/Ge/mn Data Data Volume: HPGe Performance: Analysis: Total Live Time 196/52 days ON/OFF HPGe Performance: 1.06 kg mass 0.4 keV RMS @ 10 keV 5 keV threshold [Unique Data] Range of O(1 cpd) [counts kg-1 day-1 keV-1] background c/f Dark Matter expt. Analysis: Cosmic Veto (5 ms gate) Anti-Compton (Well+Base detectors) Pulse Shape Disc. (veto elect. noise, accidentals) Efficiencies Normalization: (to <0.3%) DAQ book-keeping Monitor random triggers Monitor residual 40K peaks Monitor 10 keV Ga X-rays peak
Kuo Sheng Reactor Neutrino Laboratory : First Results
KS/P1/Ge : Spectra & Residual Based on 196/52 days of Reactor ON/OFF data No anomalous structures or residuals
KS/P1/Ge/mn : Results Fit OFF spectra to fOFF Fit ON spectra to E/keV fOFF c2/dof 12-61 p4 80/96 Fit ON spectra to fOFF + fSM + k2 fMM [10-10 mB] [using best-fit values of (fOFF;dfOFF)] Fit Results (@ c2/dof = 48/49 ): k2 = -0.5 1.4 (stat.) 0.4 (sys.) Limits derived : mn < 1.3 (1.0) X 10-10 mB @ 90(68)% C.L. Improvement in Period 2: 4p anti-Compton coverage improved inner shielding Aim of analysis threshold: ~ 5 keV study “ultra-low” energy Ge prototype [threshold : 200-300 eV] Residual Plot
Reactor mn(ne) Sensitivities Gn Sensitivities
hep-ex/0212003, in press, Phys. Rev. Lett. (2003).
KS/P1 Analysis HPGe : exploit the low threshold data Established Problem: mn and Gn for ne via : ne + e nx + e Speculative Analysis: ※ study ne flux from reactor due to neutron excitation producing e.g. 51Cr, 55Fe [distinct energy & timing …..] study mn & Gn for ne ※ anomalous Neutrino Interactions in Matter e.g. anomalous energy deposition X (>eV) ne + N nx + N + X [similar analysis as accelerator nm] ※ study possible nuclear transitions e.g. 73Ge* decays by 2g’s separated by t1/2=4.6 ms CsI(Tl) : Technical Run Event Reconstruction Background Studies Optimize for P2
Reactor as ne Source Fission Material Fission Products Neutrons odd-odd nuclei Structural materials of reactor Electron capture or + decay ( neglected ) νe Emission Captured Mostly rich in neutrons ¯ Decay back to stable valley Anti-neutrino Emisson
Simulation Result 51Cr + e- 51V + νe 55Fe + e- 55Mn + νe 59Ni + e- 59Co + νe Model of Reactor Core Simulated neutrino emission Spectrum Total neutrino emission rate normalized to per fission is: ~0.075 Correspond to an emission rate of 6 νe per fission on the energy range of < 1MeV : ~ 10-2
Tagging of 73Ge ½- 2g transitions: Event-by-Event background-free tag with PSD To do : Reactor ON/OFF analysis on the system ~1 s before the transition To look for : possible n-induced nuclear transitions
Search for Anomalous dE/dx Measure “DC” leakage current in HPGe Energy Quanta: 5 keV > X > 2 eV Expect sensensitivities: dE/dx[n+matter] ~ 10-15 dE/dx[m.i.p]
Reactor Neutrino Interaction Cross-Sections P2: SM (ne) > 2 MeV P1: MM (ne) 1-100 keV P3+: Coh. (nN) < 1 keV
CsI(Tl) Array : Highlights 40 cm length (longest commercial prod.) Energy+3D info: 10% FWHM at 660 keV s(z) <2 cm @ E>250 keV Detector Threshold ~ 20 keV PSD for g/a : > 99% Intrinsic Purity : 238U/232Th < 10-12 g/g (equil.) 40K < 10-10 g/g cosmic muon events on-site @ 46 kg target Goals: Operate 186 kg target on-site for Period-2 DAQ with large dynamic range
Period-2 CsI(Tl) Array : 186 kg, 93 crystals Single Crystal QL Vs QR 137 Cs 40 K
KS/P2: 93-Element CsI(Tl) Array (to be optimized)
KS Expt.: Future Thoughts Existing configurations: push mn/Gn sensitivities s(ne–e) scatterings analysis opened up by low threshold Push threshold lower ( X 1/10 ) coherent nN scattering [ observe SM + test exotic processes….] Insert passive targets for s(nucl.) e.g. 6Li, 7Li, 10B, 11B,2H .. s(NC) related to axial isoscalar & strange quark structure in nucleon As base to launch other projects explored by R&D program
R&D Projects Upgrading FADCs Explore New Detectors Scenarios loaded crystal scintillator (GSO, YbAG, LSO …..) ultra low energy HPGe [ O(100 eV) threshold ] CsI(Tl) for Dark Matter Searches Upgrading FADCs Trace Radio-purity with AMS ( Accelerator Mass Spectrometry) Sono-Luminescence Project (fermenting ……..) Close Contact with : CsI(Tl) CDM search @ Korea JHFBeijing LBL n project @ IHEP Ultra HE (1015 eV) n Telescope @ NTU
CsI(Tl) for CDM Searches Potential Merits: Better PSD for g/a separation than NaI(Tl) Minimal passive materials Large target mass possible (c/f em-calor. 40 tons) Highlights of R&D Program: Quenching Factor measurements with neutron beam lowest threshold data 1st direct measurement of diff. cross section in heavy nuclei PSD studies with Neural Net. & Max. Likelihood improve conventional methods N KIMS Expt. (apprd.) : 200 kg CsI(Tl) for CDM in S. Korea
TEXONO/KS FADC for SPring8 40 MHz ; 12 bit ; 32 ch/module @ 9 U VME [ c/f KS FADC : 20 MHz ; 8 bit ; 16 ch/module ] On-board processing with FPGA 1000 channels to be used in TPC in LEPS Expt. @ SPring8 by End 2002. TPC for LEPS @ SPring8 Mixed signal FADC Adapter Board 40 MHz sampling rate. 10 bits resolution with 2Vp-p dynamic range. Clock distribution with Phase Lock Loop circuit. On Board digital signal delay and Real-Time ZERO-Suppression. High capacity First In First Out Memory. Easy to use with high density connector. Prototype Measurements : (cosmic muon)
Trace Radio-purity with AMS Based at AMS facilities @CIAE with 13 MV Tandem Potential Merits: small samples, quick versatile on sample choice sensitive to a/b emitters sensitive to stable isotope & extrapolate (e.g. 39K) >103 improvements over ICP-MS [.. once prescriptions are known. ] Status : demonstrate 129I/127I < 10-12 g/g measure 40K~10-10 g/g in CsI (powder) Sensitivity goal : 10-14 g/g Future : different bases e.g. liquid scintillator 87Rb …… [238U / 232Th series after Tandem upgrade]
Status: TEXONO Collaboration: Kuo-Sheng Neutrino Lab.: Built-Up and Growing Kuo-Sheng Neutrino Lab.: Established & Operational ※Modular & Flexible Design Physics Data Taking since June 01 ※Unique HPGe Low Energy Data ※ Bkg Level ~ Underground CDM Expt. Expect Results on mn (Gn) soon ※ Other speculative analyses under way Period-2 DAQ Improved HPGe Conf. Commissioning 186 kg CsI(Tl) [+ s(ne) …] Diversified R&D Program in parallel
Scenario/Features of Further Contacts/Collaboration : new & (relatively) small group, flexible, dynamic, versatile ……… can explore new format, subjects ………… illustrative examples : tasks-sharing in KS Reactor Neutrino experiment supply detector to other experiments, e.g. FADCs for LEPS @ SPring8 in Japan bring in content/applications to expertise group, e.g. AMS @ CIAE contact and know-how/resource sharing, e.g. THU Ph.D. student @ KIMS in Korea inter-disciplinary collaboration to enhance capabilites/”parameter space” e.g. contacts with HE cosmic-ray group @ Mexico adequate resources secured for travels, long/short-term visitor positions … etc.
Summary & Outlook Neutrinos are important but strange objects history of n physics full of surprises ! Strong evidenceS of massive n’s & finite mixings Physics Beyond the Standard Model ! More experiments & projects coming up EVEN MORE EXCITEMENT ! TEXONO is also a (modest) part of it Tremendous Pleasure & Pressure !