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Low Energy Neutrino Physics at the Kuo-Sheng Nuclear Power Plant

This overview provides information on the TEXONO Collaboration at the Kuo-Sheng Nuclear Power Plant in Taiwan, focusing on their research projects in low energy neutrino physics, including results on neutrino magnetic moments and R&D projects towards neutrino-nucleus coherent scattering. The collaboration aims to study the properties and interactions of neutrinos, explore new detection channels, and understand their roles in astrophysics.

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Low Energy Neutrino Physics at the Kuo-Sheng Nuclear Power Plant

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  1. Henry T. Wong / 王子敬 Academia Sinica / 中央研究院 @ 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

  2. TEXONO Collaboration Taiwan EXperiment On NeutrinO 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. 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 • DiversifiedR&D Projects

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

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

  5. 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

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

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

  8. Neutrino Electromagnetic Properties : Magnetic Moments requires mn0 e.g. • fundamental neutrino properties & interactions ; necessary consequences of neutrino masses/mixings ; in principle can 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

  9. Magnetic Moment Searches @ KS • simple compact all-solid design : HPGe (mass 1 kg) enclosed by activeNaI/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-1keV-1kg-1 (cpd) • DAQ threshold 5 keV analysis threshold 12 keV

  10. Denote • Limit: mn(ne) < 1.0 X 10-10mB (90% CL) • X 3 data volume : expect sensitivity range mn(ne) 8 X 10-11mB ON-OFF only Combined Analysis with all Information : 1s contour

  11. Search of mn at low energy •  high signal rate & robustness: • mn>>SM [ decouple irreducible bkg  unknown sources ] • T << En ds/dT depends on total fn flux but NOT spectral shape[ flux well known : ~6 fission-n ~1.2 238U capture-nper fission ]

  12. g-n Couplings : Neutrino Radiative Decays

  13. Standard Model Cross-Sections: Neutrino-Nucleus Coherent Scattering • a fundamental neutrino interaction never been experimentally-observed • s~N2applicable at En<50 MeV where q2r2<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 En&the channel for WIMP direct detection ! • involves new energy range at low energy, many experimental challenges & much room to look for scientific surprises

  14. “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 nN coherent scattering and Dark Matter searches [ mnsearch a by-product ] 5 g 4 X 5 g

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

  16. Yangyang (襄陽) Lab (Y2L) min. 700 m of rock overburden TEXONO  KIMS @ Y2L • 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

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

  18. (keV) Background Measurements & Comparisons First-Ever Low Background Data down to 100 eV ……. ! ….. More data taking & analysis underway • 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 • Newdetection channel in Unexplored kinematic regime : “don’t know what to expect and what are expected”

  19. Single Crystal QL Vs QR (Raw Data) Z = 0 cm 208Tl 40K 137Cs Region of Interest for SMs(ne) CsI(Tl) Array (~200 kg) : s(ne) Data analysis under way…….. Z =40 cm

  20. Nuclear material Fission products Structure material n n rich nuclei －decay EC EC n rich nuclei － decay Stable isotope even-even Stable isotope Electron neutrino emission electron anti-neutrino emission Electron Neutrinos @ Reactor (PRD 72, 2005) • Evaluate ne flux at standard reactors • Derive limits on mnand Gn for ne • Explore ne flux enhancement in loaded reactor (e.g. with Cr) • Study Potential applications : • neNCC cross-section measurements, • q13 • Pu-production monitoring

  21. 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

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

  23. 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)

  24. 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 : < 10-16 g/g • Future :87Rb …… [238U / 232Th series after Tandem upgrade]

  25. Sonoluminescence Project • 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 SonoLum Pulse

  26. Summary & Outlook • 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 mn (Gn) & reactor ne

  27. Diversified Program in Parallel Main Thrust on  ~200 kg CsI(Tl) [s(ne) …] ULEGe:for scoh(nN) + CDM • Present Focus of Collaborating Groups: AS :: mnn-e S. Coherent S.  SonoLum. CIAE :: AMS SonoLum. THU ::CDM Search • Reaching Out Y2L @ Korea / Daya Bay Project (?) / Regional Framework TEXONO is a (modest) part of world neutrino physics community Tremendous Pleasure & Pressure !

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