The TEXONO Research Program on Experimental Neutrino & Astroparticle Physics Road Map in Neutrino Physics Neutrino Electromagnetic Interactions TEXONO Research Program Kuo-Sheng Neutrino Laboratory Low Energy Neutrino Physics at Kuo-Sheng R&D Projects Summary & Outlook Henry T. Wong / 王子敬 Academia Sinica / 中央研究院 @ April 2005

Neutrino Physics Road-Map L(n-mass)0 mn’s;Uij’s 0 n-Oscil. mn’s n-decays 0nbb b-spect.dist. anomal. int. ………. Grand Unified Theories (GUT) Structures & Compositions of Universe Particle Physics Nuclear Physics Astrophysics Cosmology n’s as Probe

Neutrino Electromagnetic Properties : Magnetic Moments requires mn0 e.g. fundamental neutrino properties & interactions ; necessary consequences of neutrino masses/mixings ; a channel to differentiate Dirac/Majorana neutrinos (nD/nM) look for surprises and/or constrain parameter space for model-building with future precision oscillation data explore new neutrino sources ; understand known ones explore new detection channels & techniques, esp. @ low energy explore roles of neutrinos in astrophysics

Particle Physics ※ (ni)L – (nj )R – g vertices described in general by: eij and bij are the electric & magnetic dipole moments coupling ni & nj constrained by symmetry principles, nD/nM, diagonal/transition moments (ni =/ nj ?) [ e.g. nM & i=j  b=e=0 ] ※ Experimental measureable “neutrino magnetic moment” depends on |nl > after oscillation distance L Subtleties/Complications: measureable is an effective/convoluted parameter (c.f. 0nbb) physics information depends on exact |n> compositions at the detector

Experimental Manifestations Minimally-Extended Standard Model with nD : mn VERY small  many ways to significantly enhance it (nM, WR …..) study consequences from the change of neutrino spin states in a (astrophysical) medium 1/T spectral shape in n-e scattering, T is electron recoil energy Neutrino radiative decays …………

Astrophysics Bounds/Indications From: Big Bang Nucleosynthesis degree of freedom Stellar Cooling via Cooling of SN1987a via nactive  nsterile Absence of solar [KamLAND-03 < 2.8x10-4 ; n04: HE eventsstay tuned] ranges of mn(astro) < 10-10 – 10-12 mB Complications/Assumptions : astrophysics modeling (e.g. Solar B-field) Neutrino properties (e.g nD / nM ; no other anomalous effects) Global treatment (e.g. effects from matter, oscillations ; interference/competitions among channels ……)

Magnetic Moments & Solar Neutrinos For completeness/historical footnote …… Magnetic Moments & Solar Neutrinos ne produced in the Sun interact with B to become nx(xe), via spin-flavor precession(SFP), with or without resonance effects in solar medium. used to explain anti-correlation of Cl-n data with Sun-spot cycles in late 80’s scenario compatible with all solar neutrino data KamLAND independently confirms LMA as the solution for solar neutrino problem  SFP cannot be the dominant contribution [n data + LMA allowed region + no ]  constrain  mn B dr : [Akhmedov et al., Miranda et al. …] ranges of mn(solar) < 10-10 – 10-12 mB (after B modeling)

Direct Experiments using sources understood by independent means : reactor n , accelerator n , n at detector , n-sources (future) look for 1/T excess due to n-e scattering via mn channel over background and Standard Model processes reactor n : reactor ON/OFF comparison to filter out background uncertainties n : account for background spectra by assumptions/other constraints limits independent of |n>final : valid for nD/nM & diag./tran. moments -- no modeling involved interpretation of results : need to take into account difference in |n>initial

Solar n : SK & Borexino ※ SK spectral distortion over oscillation “bkg” [hep-ex/0402015] 8B n SK alone : mn(n ) < 3.6 X 10-10 mB (90% CL) + all n data : mn(n-LMA ) < 1.3 X 10-10 mB (90% CL) + KamLAND : mn(n-LMA ) < 1.1 X 10-10 mB (90% CL) ※ Borexino/CTF spectral analysis [PLB 563,2003] mainly 7Be n bkg=0 : mn(n ) < 1.2 X 10-9 mB (90% CL) Assume linear bkg + best fit : mn(n) < 5.5 X 10-10 mB (90% CL)

Accelerator n : LSND & DONUT ※ LSND [PRD 63, 2001]: select “single electron” events taking SM s(nm-e), measured s(ne-e)  agrees with SM  set limit ※ DONUT [PLB 513, 2001]: observed nt from Ds decays at expected level look for “single electron” events at level >> SM s(n-e) observed 1 event with 2.3 expected background @ e=9% limit: mn(nt) < 3.9 X 10-7 mB (90% CL)

Reactor n @ Bugey : MUNU CF4 TPC (total mass 11.4 kg; containment e~0.5 at 1 MeV) excellent “single electron” event selection via 4p liquid scintillator & tracking distinguish start/end of track & measure scattering angle w.r.t. reactor direction  measure neutrino energy Reactor ON/OFF comparison  forward/background events comparison

MUNU data (66.6 d ON/16.7 d OFF) [PLB 564, 2003] excess of counts < 900 keV ; NO explanations yet [fn(reactor) below 2 MeV not well-known] limits depends on energy range taken : Visual scan T > 700 keV mn(ne) < 1.4 X 10-10 mB (90% CL) Visual scan T > 900 keV mn(ne) < 1.0 X 10-10 mB (90% CL) Auto scan T > 300 keV mn(ne) < 1.7 X 10-10 mB (90% CL) studies of hidden n-sources and/or low energy background necessary

….. But not very good fits New Results from MUNU (hep-ex/0502) T > 700 keV : mn(ne) < 0.9 X 10-10 mB (90% CL) ….. But not very good fits

TEXONO Research Program ………...

TEXONO* Collaboration W.C. Chang, K.C. Cheng, M.H. Chou, H.C. Hsu, C.H. Iong, G.C.Jon, F.S. Lee, S.C.Lee, H.B. Li, V. Singh, D.S. Su, P.K.Teng, H.T.K.Wong,  S.C. Wu Academia Sinica, Taipei, Taiwan W.P. Lai Chung Kuo Institute of Technology, Taipei, Taiwan C.H. Hu, W.S. Kuo, T.R. Yeh Institute of Nuclear Energy Research, Lungtan, Taiwan H.Y. Liao, S.T. Lin, M.Z. Wang National Taiwan University, Taipei, Taiwan F.K. Lin National Tsing Hua University, Hsinchu, Taiwan Z.M. Fang, R.F. Su Nuclear Power Station II, Kuosheng, Taiwan J. Bao, K.J. Dong, 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, J. Nie, Z.P.Mao, J.F.Qiu, H.Y.Sheng, P.L.Wang, X.W. Wang, D.X.Zhao, P.P.Zhao, B.A.Zhuang 　 Institute of High Energy Physics, Beijing, China J.Q. Lu, T.Y. Chen Nanjing University, Nanjing, China Y. An, D.Z. Liu, Q. Yue, Y.F. Zhu Tsing Hua University, Beijing, China C.Y. Chang, G.C.C. Chang University of Maryland, Maryland, U.S.A. M. Deniz, M. Zeyrek Middle East Technical University, Turkey Co-Prinicipal Investigators Ph.D. Students 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 Results: Dec 2002.

Poineering Efforts : “Zero-Background Experiment” ! TEXONO Overview Program: Kuo-Sheng Reactor Neutrino Laboratory ※ reactor : high flux of low energy electron anti-neutrinos ※ oscillation expts.  mn0  anomalous n properties & interactions ※ n physics full of surprises , need intense n-source  study/constraint new regime wherever experimentally accessible  explore possible new detection channels R&D Projects Poineering Efforts : “Zero-Background Experiment” ! KS Expt: 1st large-scale particle physics experiment in Taiwan TEXONO Coll. : 1st big research Coll. % Taiwan & China [feature report in Science, Vol. 300, 1074 (2003) ]

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Kuo-Sheng Nuclear Power Plant KS NPS-II : 2 cores  2.9 GW KS n Lab: 28 m from core#1

Kuo Sheng Reactor Neutrino Laboratory Front Gate Front View (cosmic vetos, shieldings, control room …..) Configuration: Modest yet Unique Flexible Design: Allows different detectors conf. for different physics Inner Target Volume

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]

Kuo Sheng Reactor Neutrino Laboratory : First Results

Reactor n @ Kuo-Sheng : TEXONO simple compact all-solid design : HPGe (mass 1 kg) enclosed by active NaI/CsI anti-Compton, further by passive shieldings & cosmic veto focus on 10-100 keV range for high signal rate & robustness: mn >> SM [decouple irreducible bkg  unknown sources make searches more conservative ] T<<En  ds/dT depends on total fn flux but NOT spectral shape [well known : ~6 fission-n  ~1.2 238U capture-n per fission ] selection: single-event after cosmic-veto, anti-Comp., PSD Inner Target Volume

Cosmic Veto, Anti-Compton & PSD Events correlated to Cosmic No signal in Anti-Compton detectors PSD : Events Selected

TEXONO data (4712/1250 hours ON/OFF) [PRL 90, 2003] comparable bkg level to underground CDM experiment at 10-20 keV : ~ 1 day-1keV-1kg-1 (cpd) analysis threshold 12 keV No excess of counts ON/OFF comparison Limit: mn(ne) < 1.3 X 10-10 mB (90% CL) more data/improvement to get to sensitivity range mn(ne) 1.0 X 10-10 mB

Reactor mn(ne) Sensitivities Gn Sensitivities

Coverage in International Press

Combined Analysis [Grimus et al., …. ] use all available information, incl. LMA global fit & error contour take nM  only transition moments ni  nj adopt mn direct limits from SK spectral shape & reactor expts “Total” Magnetic Moment : Reactor n: n at SK:

KS Physics Program : Periods I & II & III HPGe [1 kg] : mn + Gn : x2 more data from PRL improved background & analysis study reactor ne flux & physics potentials study possible nuclear transitions e.g. 73Ge* decays by 2g’s separated by t1/2=4.6 ms Study possible reactor axion searches CsI(Tl) [186 kg] : attempt measurement of Standard Model s(nee-)  sin2qw at MeV range Prototype ULE-HPGe [5 g] : threshold < 300 eV  ~ 100 eV explore potentials on nN coherent scattering & CDM

Reactor Neutrino Interaction Cross-Sections On-Going Data Taking: SM s(ne) T > 2 MeV R&D : Coh. (nN) T < 1 keV Results & More Data: mn(ne) T ~ 1-100 keV

Period II Installation – HPGe

Period-2 CsI(Tl) Array : 186 kg, 93 crystals Goal : to make a measurement of neutrino-electron scattering cross-sections, i.e. sin2qw at q~MeV range

Single Crystal QL Vs QR (Raw Data) Z = 0 cm Z =40 cm 208Tl 40K 137Cs Region of Interest for SM s(ne)

electron neutrino flux Simulation of reactor electron neutrino flux Nuclear material Fission products n Structure material Neutron sampling Geometry description Probability of EC decay Electron neutrino flux Physical model n rich nuclei －decay EC EC Electron neutrino emission n rich nuclei － decay Stable isotope even-even Stable isotope electron anti-neutrino emission

Exclusion Plot for ne Radiative Decays:

Looking for n-induced 73Ge* 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/after the transition n-induced events signature: excess in the “ON+before” spectra

Reactor Axions Analysis with HPGe data Like TEXONO HPGe Reactor core has intense M1 transitions : e.g. 7Li, 91Y, 97Nb etc. Signature : peak at transition energy at HPGe due to Primakoff conversion

“Ultra-Low-Energy” HPGe Prototype mass 5 g ; can be constructed in multi-array form threshold <100 eV after modest PSD (lowest achieved for bulk radiation detectors) background measurement on-site Nov 03 study appl. in nN coherent scattering and Dark Matter searches

ULE-HPGe Prototype Results PSD Cut Threshold ~ 100 eV Threshold < 100 eV Signal Band

Sensitivity Plot for CDM-WIMP search with 1 kg ULEGe at 100 eV threshold ………

min. 700 m of rock overburden TEXONO-KIMS Connections ……… KIMS: funded Dark Matter program with underground facility @ Y2L in Korea TEXONO CsI(Tl) work & KS design adapted in KIMS’s set up at Y2L Install LE-HPGe to Y2L for measurement 04/05  organized by THU team ; background below 1 keV, CDM searches may evolve into a full-scale (1 kg) CDM experiment may broaden framework in the future (regular joint meetings ; sharing of know-how ….) Yangyang (襄陽) Lab (Y2L) min. 700 m of rock overburden

Installations of ULEGe at Y2L in March 2005 Background studies Feasibilities studies for CDM searches

Possibilities for Reactor q13 ……… IHEP’s q13 Proposal at Daya Bay near Hong Kong  Compare Reactor close & at ~2 km to <1%  More Powerful Reactor Complex  More overburden possible from mountains Tunnel Digging Cost Less in China A High Profile (i.e. competitive subject) Close contact with IHEP & Monitoring progresses & Exploring possibilities

R&D Projects Upgrading FADCs (+ FPGA etc. capabilities…..) Explore New Detectors Scenarios (LEn, CDM …)  other crystal scintillators (GSO …)  ultra low energy HPGe [ O(100 eV) threshold ] Feasibility Studies on CsI(Tl) for Dark Matter Searches  Approved Experiment @ Korea by KIMS Coll. Upgrading FADCs (+ FPGA etc. capabilities…..)  for LEPS @ SPring8 Trace Radio-purity with AMS ( Accelerator Mass Spectrometry)  1st goal : sensitivity of 10-14 g/g in 40K Sono-Luminescence Project (inter-disciplinary) Completed On-Going Completed Completed On-Going On-Going

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 Results (PLB 02): 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. :  200 kg CsI(Tl) for CDM in S. Korea

TEXONO/KS FADC for SPring8/LEPS 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 used in TPC in LEPS Expt. @ SPring8 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. (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)  develop techniques for K in liquid scintillator Sensitivity goal : < 10-14 g/g Future :  87Rb …… [238U / 232Th series after Tandem upgrade] ====== NSF funded projected in China , led by CIAE =====

CIAE-AMS system

Sonoluminescence Project (AS,CIAE, NCU, NCCU….) a frontier subject with possible surprises new directions : to explore subjects we do not know inter-disciplinary research  a testing ground from HEP group future possibility Table-top experiments, pursue-able in several labs  balance the other big & long time-scale projects  use HEP approaches Focus :  understand physics mechanism  emissions of high energy radiations SonoLum Pulse

Repeating ORNL experiment in preparation at CIAE SL Typical Set-Up SL Typical Cycle Repeating ORNL experiment in preparation at CIAE

SonoLum Pulse

TEXONO STATUS TEXONO Collaboration:  Built-Up & 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. Results published on mn (Gn)  Other analyses under way Period-II/III DAQ  Improved HPGe Conf.  196 kg CsI(Tl) [s(ne) …]  LEGe: study potentials for scoh(nN) Diversified R&D Program in parallel Focus at AS :: mn  n-e S.  Coherent S.  SonoLum. CIAE :: AMS  SonoLum. THU :: CDM Search Reaching Out  Y2L @ Korea / Daya Bay Project (?) / Regional Framework

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 (a modest) part of world neutrino physics community Tremendous Pleasure & Pressure !