Research Program of TEXONO Collaboration on Neutrino

Research Program of TEXONO Collaboration on Neutrino & Astroparticle Physics Ø Overview Ø Kuo-Sheng Period I Program Results on Neutrino Magnetic Moment Ø Period II Data Taking & Focus Ø R & D Program Henry T. Wong / 王子敬 Academia Sinica / 中央研究院 @ 2 nd NCTS Workshop on Astropart. Phys. January 2003

Experimental Neutrino Physics ……

* 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 *Taiwan EXperiement On Neutrin. O Home Page @ http: //hepmail. phys. sinica. edu. tw/~texono/ 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, U. S. A. † ¶ Co-Prinicipal Investigators Project Leaders Ph. D. Students HISTORY v. Initiate : Chang Chung-Yung 1996 v. First Collab. Meeting/Official Start : October 1997 v. First Paper : October 1998 v. KS Reactor Experiment Installation : June 2000 v. First Ph. D. : Liu Yan , July 2000 v. First Physics Data Taking : June 2001. v. First Physics Result : December 2002

TEXONO Overview Goals : Ø Neutrino and Astroparticle Physics Starting phase: 1 st particle physics expt in Taiwan Ø Build up a Qualified Group 1 st big research Coll. % Taiwan & China Program: Ø Kuo-Sheng Reactor Neutrino Lab. ※ reactor : high flux of low energy electron anti-neutrinos ※ mn 0 anomalous n properties & interactions ※ n’s strange & full of surprises study/constraint new regime wherever possible experimentally Ø R&D Projects diversified program ※ reactor program as base ※ explore various future scenarios

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 Ø High flux of ne (also …. . ne ) Ø Modular Design : independent detector, electronics, shielding Ø high-Z target, large re Ø Improved detector performance: good energy & spatial resolution, Configuration: low threshold, a/g separation Modest yet Unique Ø Elaborate electronics+DAQ+control sys. Flexible Design: complete record of pulse shape + timing info. Allows different detectors Ø Elaborate Shieldings radon purge & 4 p cosmic veto conf. for different physics

Kuo Sheng Reactor Neutrino Laboratory Front Gate Front View (cosmic vetos, shieldings, control room …. . ) Inner Target Volume

KS Expt. : Period I Configuration Period I : June 01 – April 02 (60 days OFF) Shielding & Veto [one side] ULB-HPGe + Anti. Comptons Cs. I(Tl) Array (46 kg)

KS Expt: Period I Detectors ULB-HPGe [1 kg] FADC Readout [16 ch. , 20 MHz, 8 bit] Cs. I(Tl) [46 kg] Multi-Disks Array [600 Gb]

Ø mn mn with Reactor ne parametrize possible ni. L nj. R + g vertices both i = j “diagonal” & i j “transition” moments Ø Experimental Probe: Study ne + e - n. X + 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 Ø Neutrino Radiative Decay (Gn): sm & Gn related: same vertices – real g for Gn Electron Recoil Spectra

PDG Limit : 1. 5 X 10 -10 m. B (from SK spectral shape) an allowed solution for the solar neutrino data (before Kam. LAND)

KS/P 1/Ge/mn Data Ø Data Volume: Total Live Time 196/52 days ON/OFF Ø HPGe Performance: 1. 06 kg mass 0. 4 ke. V RMS @ 10 ke. V 5 ke. V threshold [Unique Data] Range of O(1 cpd) [counts kg-1 day-1 ke. V-1] background c/f Dark Matter expt. Ø Analysis: Cosmic Veto (5 ms gate) Anti-Compton (Well+Base detectors) Pulse Shape Disc. (veto elect. noise, accidentals) Ø Efficiencies Normalization: (to <0. 3%) DAQ book-keeping Monitor random triggers Monitor residual 40 K peaks Monitor 10 ke. V Ga X-rays peak

Kuo Sheng Reactor Neutrino Experiment : First Results

KS/P 1/Ge : Spectra & Residual Ø Based on 196/52 days of Reactor ON/OFF data ØNo anomalous structures or residuals

KS/P 1/Ge/mn : Results Ø Fit OFF spectra to f. OFF E/ke. V 12 -61 f. OFF p 4 c 2/dof 80/96 Ø Fit ON spectra to f. OFF + f. SM + k 2 f. MM [10 -10 m. B] [using best-fit values of (f. OFF; df. OFF)] Fit Results (@ c 2/dof = 48/49 ): k 2 = -0. 5 1. 4 (stat. ) 0. 3 (sys. ) Limits derived : mn < 1. 3 (1. 0) X 10 -10 m. B @ 90(68)% C. L. Ø Improvement in Period 2: 4 p anti-Compton coverage improved inner shielding Aim of analysis threshold: ~ 5 ke. V study “ultra-low” energy Ge prototype [threshold : 200 -300 e. V] Residual Plot

Reactor mn(ne) Sensitivities Gn Sensitivities

KS/P 1 Analysis HPGe : exploit the low threshold data Ø Established Problem: mn and Gn for ne via : ne + e nx + e Ø Speculative Analysis: ※ study ne flux from reactor due to neutron excitation producing e. g. 51 Cr, 55 Fe [distinct energy & timing …. . ] study mn & Gn for ne ※ anomalous Neutrino Interactions in Matter e. g. anomalous energy deposition X (>e. V) ne + N nx + N + X [similar analysis as accelerator nm] ※ study possible nuclear transitions e. g. 73 Ge* decays by 2 g’s separated by t 1/2=4. 6 ms Cs. I(Tl) : Technical Run Ø Event Reconstruction Ø Background Studies Ø Optimize for P 2

Reactor as ne Source Fission Material Fission Products Mostly rich in neutrons ¯ Decay back to stable valley Anti-neutrino Emisson Neutrons Captured Structural materials of reactor odd-odd nuclei Electron capture or + decay ( neglected ) νe Emission

Simulation Result 51 Cr + e- 55 Fe + e- 59 Ni + e- 51 V + νe 55 Mn + ν e 59 Co + ν e Model of Reactor Core Simulated neutrino emission Spectrum Ø Total neutrino emission rate normalized to per fission is: ~0. 075 Ø Correspond to an emission rate of 6 νe per fission on the energy range of < 1 Me. V : ~ 10 -2

Tagging of 73 - Ge ½ 2 g transitions: ØEvent-by-Event background-free tag with PSD ØTo do : Reactor ON/OFF analysis on the system ~1 s before the transition ØTo look for : possible n-induced nuclear transitions

Search for Anomalous d. E/dx Ø Measure “DC” leakage current in HPGe Ø Energy Quanta: 5 ke. V > X > 2 e. V Ø Expect sensensitivities: d. E/dx[n+matter] ~ 10 -15 d. E/dx[m. i. p]

Reactor Neutrino Interaction Cross-Sections P 2: SM (ne) > 2 Me. V P 3+: Coh. (n. N) < 1 ke. V P 1: MM (ne) 1 -100 ke. V

Cs. I(Tl) Array : Highlights Ø 40 cm length (longest commercial prod. ) Ø Energy+3 D info: 10% FWHM at 660 ke. V s(z) <2 cm @ E>250 ke. V Ø Detector Threshold ~ 20 ke. V Ø PSD for g/a : > 99% Ø Intrinsic Purity : 238 40 232 U/ Th < 10 K < 10 -12 g/g (equil. ) g/g cosmic muon events on-site @ 46 kg target Goals: Ø Operate 186 kg target on-site for Period-2 Ø DAQ with large dynamic range

Period-2 Cs. I(Tl) Array : 186 kg, 93 crystals Single Crystal QL Vs QR 137 Cs 40 K

KS/P 2: 93 -Element Cs. I(Tl) Array (to be optimized)

KS Expt. : Future Thoughts Ø Existing configurations: push mn/Gn sensitivities s(ne–e) scatterings analysis opened up by low threshold Ø Push threshold lower ( X 1/10 ) coherent n. N scattering [ observe SM + test exotic processes…. ] Ø Insert passive targets for s(nucl. ) e. g. 6 Li, 7 Li, 10 B, 11 B, 2 H. . s(NC) related to axial isoscalar & strange quark structure in nucleon Ø As base to launch other projects explored by R&D program

R&D Projects Ø Explore New Detectors Scenarios loaded crystal scintillator (GSO, Yb. AG, LSO …. . ) ultra low energy HPGe [ O(100 e. V) threshold ] Ø Cs. I(Tl) for Dark Matter Searches Ø Upgrading FADCs Ø Trace Radio-purity with AMS ( Accelerator Mass Spectrometry) Ø Sono-Luminescence Project (fermenting ……. . ) ØClose Contact with : Cs. I(Tl) CDM search @ Korea JHF Beijing LBL n project @ IHEP 15 Ultra HE (10 e. V) n Telescope @ NTU

Cs. I(Tl) for CDM Searches Potential Merits: Ø Better PSD for g/a separation than Na. I(Tl) Ø Minimal passive materials Ø Large target mass possible (c/f em-calor. 40 tons) Highlights of R&D Program: Ø Quenching Factor measurements with neutron beam lowest threshold data Ø 1 st direct measurement of diff. cross section in heavy nuclei Ø PSD studies with Neural Net. & Max. Likelihood improve conventional methods N KIMS Expt. (apprd. ) : 200 kg Cs. I(Tl) for CDM in S. Korea

TEXONO/KS FADC for SPring 8 Ø 40 MHz ; 12 bit ; 32 ch/module @ 9 U VME [ c/f KS FADC : 20 MHz ; 8 bit ; 16 ch/module ] Ø Ø On-board processing with FPGA 1000 channels to be used in TPC in LEPS Expt. @ SPring 8 by End 2002. TPC for LEPS @ SPring 8 Mixed signal FADC Adapter Board § 40 MHz sampling rate. § 10 bits resolution with 2 Vp-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 Ø Based at AMS facilities @CIAE with 13 MV Tandem Ø Potential Merits: small samples, quick versatile on sample choice sensitive to a/ emitters sensitive to stable isotope & extrapolate (e. g. 39 K) >103 improvements over ICP-MS [. . once prescriptions are known. ] Ø Status : demonstrate 129 I/127 I < 10 -12 g/g measure 40 K~10 -10 g/g in Cs. I (powder) Sensitivity goal : 10 -14 g/g Ø Future : different bases e. g. liquid scintillator 87 Rb …… [238 U / 232 Th series after Tandem upgrade]

Status: Ø TEXONO Collaboration: Built-Up and Growing Ø 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. Ø Expect Results on mn (Gn) soon ※ Other speculative analyses under way Ø Period-2 DAQ Improved HPGe Conf. Commissioning 186 kg Cs. I(Tl) [+ s(ne) …] Ø Diversified R&D Program in parallel

Summary & Outlook Ø Neutrinos are important but strange objects history of n physics full of surprises ! Ø Strong evidence. S of massive n’s & finite mixings Physics Beyond the Standard Model ! Ø More experiments & projects coming up EVEN MORE EXCITEMENT ! Ø TEXONO is also a (modest) part of it Tremendous Pleasure & Pressure !