Low Energy Neutrino Physics at the Kuo-Sheng Nuclear Power Plant  Overview of TEXONO Collaboration  Kuo-Sheng Reactor Neutrino Laboratory  Results on Neutrino Magnetic Moments  R&D projects towards Neutrino-Nucleus Coherent Scattering  Survey of Other Research Program (KS and non-KS based)  Summary & Outlook Henry T. Wong / 王子敬 Academia Sinica / 中央研究院

TEXONO Collaboration Collaboration : Taiwan (AS, INER, KSNPS, NTU) ; China (IHEP, CIAE, THU, NJU) ; Turkey (METU) ; USA (UMD) Program: Low Energy Neutrino & Astroparticle Physics  Kuo-Sheng (KS) Reactor Neutrino Laboratory  reactor : high flux of low energy electron anti-neutrinos  oscillation expts.  m  0  anomalous properties & interactions  physics full of surprises, need intense -source ※ study/constraint new regime wherever experimentally accessible ※ explore possible new detection channels  Diversified R&D Projects Taiwan EXperiment On NeutrinO

 Poineering Efforts : “Zero-Background Experiment” !  KS Expt: 1 st large-scale particle physics experiment in Taiwan  TEXONO Coll. : 1 st big research Coll. % Taiwan & China

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

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

R&D :  Coh. ( N)  T < 1 keV Results & More Data:   ( e )  T ~ keV On-Going Data Taking & Analysis  SM  ( e)  T > 2 MeV Reactor Neutrino Interaction Cross-Sections massqualityDetector requirements

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

 fundamental neutrino properties & interactions ; necessary consequences of neutrino masses/mixings ; in principle can differentiate Dirac/Majorana neutrinos ( D / M )  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, low energy  explore roles of neutrinos in astrophysics Neutrino Electromagnetic Properties : Magnetic Moments e.g. requires m  0

Magnetic Moment KS  simple compact all-solid design : HPGe (mass 1 kg) enclosed by active NaI/CsI anti-Compton, further by passive shieldings & cosmic veto  selection: single-event after cosmic-veto, anti-Comp., PSD  TEXONO data (4712/1250 hours ON/OFF) [PRL 90, 2003]  background comparable to underground CDM experiment : ~ 1 day -1 keV -1 kg -1 (cpd)  DAQ threshold 5 keV analysis threshold 12 keV

Combined Analysis with all Information :  Denote  Limit:   e ) < 1.0 X  B (90% CL)  X 3 data volume : expect sensitivity range   e )  8 X  B 1  contour ON- OFF only

Search of  at low energy  high signal rate & robustness:   >>SM [ decouple irreducible bkg  unknown sources ]  T << E  d  /dT depends on total  flux but NOT spectral shape [ flux well known : ~6 fission-  ~ U capture- per fission ]

 Couplings : Neutrino Radiative Decays

 a fundamental neutrino interaction never been experimentally- observed   ~N 2 applicable at E <50 MeV where q 2 r 2 <1  a sensitive test to Stardard Model  an important interaction/energy loss channel in astrophysics media  a promising new detection channel for neutrinos, without strict lower bound on E & the channel for WIMP direct detection !  involves new energy range at low energy, many experimental challenges & much room to look for scientific surprises Standard Model Cross-Sections: Neutrino-Nucleus Coherent Scattering

“Ultra-Low-Energy” HPGe Prototype  ULEGe – developed for soft X-rays detection ; easy & inexpensive & robust operation  Prototype : (I) 5 g ; (II) 4 X 5 g ; (III) 10 g ; (IV) segmented 20 g  threshold <100 eV after modest PSD [lowest achieved for bulk radiation detectors]  study feasibilities for 1-kg-ish detector for  coherent scattering and Dark Matter searches [   search a by-product ] 5 g 4 X 5 g

ULE-HPGe Prototype Results ※ threshold ~100 eV, calibration by linear extrapolation from 1-6 keV ※ PSD possible to suppress noise edge Threshold ~ 100 eV

Yangyang ( 襄陽 ) Lab (Y2L) min. 700 m of rock overburden  Install 5 g ULB-ULEGe at Y2L on January 2005  Study background and feasibility for CDM searches  may evolve into a full-scale (1 kg) CDM experiment TEXONO  Y2L

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

Background Measurements & Comparisons  Similar background at KS & Y2L  Apparent difference between 5 g & 1 kg due to scaling with surface area instead, reproduced in simulations  i.e. background can be ~ O(1 cpd) at > 1 keV range for 1 kg ULEGe in compact array form  New detection channel in Unexplored kinematic regime :  “don’t know what to expect and what are expected” (keV) First-Ever Low Background Data down to 100 eV ……. ! ….. More data taking & analysis underway

CsI(Tl) Array (~200 kg) :  e) Z =40 cm Single Crystal Q L Vs Q R (Raw Data) Region of Interest for SM  e) Z = 0 cm 208 Tl 40 K 137 Cs Data analysis under way……..

Electron Reactor (PRD 72, 2005) Nuclear material Fission products n rich nuclei Stable isotope Structure material n  － decay  －  decay EC even-even Electron neutrino emission electron anti- neutrino emission  Evaluate e flux at standard reactors  Derive limits on  and  for e  Explore e flux enhancement in loaded reactor (e.g. with Cr)  Study Potential applications :  e NCC cross-section measurements,   13  Pu-production monitoring

Tagging of 73 Ge ½ - 2  transitions  Event-by-Event background-free tag with PSD  To do : Reactor ON/OFF analysis on the system ~1 s before/after the transition  -induced events signature: excess in the “ON+before” spectra Looking for -induced 73 Ge *

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

 40 MHz ; 12 bit ; 32 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 SPring8 TPC for SPring8  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. Mixed signal FADC Adapter Board TEXONO/KS FADC for SPring8/LEPS (cosmic muon)

Trace Radio-purity with AMS  Based at AMS with 13 MV Tandem  Potential Merits:  small samples, quick  versatile on sample choice  sensitive to  emitters  sensitive to stable isotope & extrapolate (e.g. 39 K)  >10 3 improvements over ICP-MS [.. once prescriptions are known. ]  Status :  demonstrate 129 I/ 127 I < g/g  measure 40 K~ g/g in CsI (powder)   develop techniques for K in liquid scintillator Sensitivity goal : < g/g  Future :  87 Rb …… [ 238 U / 232 Th series after Tandem upgrade]

Sonoluminescence Project SonoLum Pulse  a frontier subject with possible surprises  new directions : to explore subjects we do not know  inter-disciplinary research  new research style and experience enriching  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

 TEXONO Collaboration:  Built-Up from Scratch & Maturing  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     & reactor e Summary & Outlook

 Diversified Program in Parallel Main Thrust on  ~200 kg CsI(Tl) [  ( e) …]  ULEGe: for  coh ( N) + CDM  Present Focus of Collaborating Groups: AS ::   -e S.  Coherent S.  SonoLum. CIAE :: AMS  SonoLum. THU :: CDM Search  Reaching Out  Korea / Daya Bay Project (?) / Regional Framework TEXONO is a (modest) part of world neutrino physics community Tremendous Pleasure & Pressure !