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TEXONO Collaboration & Kuo-Sheng Laboratory & Program Overview

Hightlights and Status of the TEXONO Research Program on Low Energy Neutrino & Dark Matter Physics. TEXONO Collaboration & Kuo-Sheng Laboratory & Program Overview Results on Neutrino Magnetic Moments, Reactor Electron Neutrinos and Reactor Axion Search

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TEXONO Collaboration & Kuo-Sheng Laboratory & Program Overview

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  1. Hightlights and Status of the TEXONO Research Program on Low Energy Neutrino & Dark Matter Physics • TEXONO Collaboration & Kuo-Sheng Laboratory & Program Overview • Results on Neutrino Magnetic Moments, Reactor Electron Neutrinos and Reactor Axion Search • Future Direction - Ultra-Low Energy Detectors for Neutrino-Nucleus Coherent Scattering & Dark Matter Searches • Outlook. Henry T. Wong / 王子敬 Academia Sinica / 中央研究院 November 2007 KIMS-TEXONO Workshop Seoul National U. @

  2. TEXONO Collaboration Taiwan EXperiment On NeutrinO Collaboration : • Taiwan (AS, INER, KSNPS, NTU,NCU,NCCU) • China (IHEP, CIAE, THU, NJU, NKU) • Turkey (METU) • India (BHU) + Close Partnership (KIMS Collaboration in S. Korea) Poineering Efforts : “Zero-Background Experiment” ! • KS Expt:1st large-scale particle physics experiment in Taiwan • TEXONO Coll. : 1st big research Coll. % Taiwan & China

  3. Neutrino Physics at (L~0) Reactor ?? Rationale : • Need neutrino source to do neutrino physics : reactor is a high-flux, understood and controlled source AND free as well !! • oscillation expts.mn0  anomalous n properties & interactions • Experimental neutrino physics has been full of surprise • Worth exploring any experimentally accessible parameter space • May place constraints to interpretation of precision oscillation data • Explore new neutrino sources & detection channels for future studies

  4. Kuo-Sheng Nuclear Power Plant KS NPS-II : 2 cores  2.9 GW NPS-IV

  5. Kuo Sheng Reactor Neutrino Laboratory Front Gate • 28 m from core#1 @ 2.9 GW • Shallow depth : ~30 meter-water-equivalent • Reactor Cycle : ~50 days OFF every 18 months

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

  7. KS Laboratory : Detectors ULE-ULB-HPGe Prototype [20 g] ULB-HPGe [1 kg] CsI(Tl) [200 kg] Multi-Disks Array [600 Gb] FADC Readout [16 ch., 20 MHz, 8 bit]

  8. Reactor Neutrino Spectra Evaluation… Reactor Operation Data Nuclear Physics

  9. quality Detector requirements mass Reactor Neutrino Interaction Cross-Sections 1 counts / kg-keV-day On-Going Data Taking & Analysis • SM s(ne) • T > 2 MeV • R&D : • Coh. (nN) • T < 1 keV Threshold ~ 100 eV Completed Results : • mn(ne) : T~1-100 keV • Axions : T ~ keV-MeV

  10. Research Program of TEXONO : • Search of Neutrino Magnetic Moments [this talk] • Studies of Reactor Electron Neutrino [this talk] • Search of Reactor Axions [this talk] • Measurement of neutrino-electron scattering cross-sections (i.e. sin2qW at MeV range) with CsI(Tl) crystals [M.Deniz’s talk] • Studies of possible neutrino induced nuclear transitions in Ge & CsI [F.K.Lins’ talk] • Measurement of Trace-Radiopurity with Accelerator Mass Spectrometry [Results Published on I129, K40; Omitted] • Sonoluminescence [F.K. Lin’s talk]

  11. Future Direction [This+H.B.Li’s+S.K.Lin’s talk]: • Open new detection channel and detector window down to 100 eV • testing “ULEGe” prototypes at AS+KS+Y2L • sub-keV Quenching Factor measurements at CIAE • Physics Goals: • First observation of neutrino-nucleus coherent scattering at KS • Dark Matter Searches at low-WIMP-mass region at Y2L • Improvement on Neutrino Magnetic Moment sensitivities • Expect ready for a major experiment with ~1 kg scale detector at 2008+ [scale : O(1 MUSD )]

  12. Neutrino Electromagnetic Properties : Magnetic Moments requires mn0 e.g. • a conceptually rich subject ; much neutrino physics & astrophysics can be explored n-osc. : Dmn , Uij 0nbb : mn, Uij , nD/nM • mn: mn, Uij , nD/nM , n  g • fundamental neutrino properties & interaction ; necessary consequences of neutrino masses/ mixings ; in principle can differentiate Dirac/Majorana neutrinos • explore roles of neutrinos in astrophysics

  13. 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 (571/128 days) ON/OFF)[PRL 90, 2003 ; PRD 75, 2007] • background comparable to underground CDM experiment : ~ 1 day-1keV-1kg-1 (cpd) • DAQ threshold 5 keV analysis threshold 12 keV

  14. ON/OFF Residual Plot : Limit: mn(ne)< 7.4 X 10-11mB @ 90% CL

  15. Direct Experiments at Reactors • 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 ]

  16. g-n Couplings : Neutrino Radiative Decays

  17. First exploration of electron-neutrino production at reactors ….

  18. 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

  19. c.f. ~7.2 /fission Regular Reactor : X 10-4 Loaded Reactor :

  20. Exploration of possible axion emission at reactor ….. PRD 75 (2007)  Idea : Axions can be emitted in gamma-decays AND the power reactor is THE most powerful terrestrial radioactivity source.

  21. Production: Detection: Experimental Search :

  22. Results: • Improved laboratory limits on gaee for Bra>10-9 • Exclude DFSZ/KSVZ Models for axion mass 104-106 eV

  23. “Ultra-Low-Energy” HPGe Detectors • ULEGe – developed for soft X-rays detection ; easy & inexpensive & robust operation • Prototypes built and studied : • 5 g @ Y2L • 4 X 5 g @ KS/Y2L • 10 g @ AS/CIAE • segmented 180 g @ AS/KS • Being built : 500 g single element • Physics for O[100 eV threhold1 kg mass1 cpd detector]: • nN coherent scattering • Low-mass WIMP searches • Improve sensitivities on mn • Implications on reactor operation monitoring • Open new detector window & detection channel available for surprises

  24. ULEGe-Prototype built & being studied : 5 g 10 g 4 X 5 g Segmented 180 g with dual readout

  25. R&D Program towards Realistic O(1 kg) Size Experiments (both nN & CDM) : • measure & study background at sub-keV range at KS & Y2L ; design of active & passive shielding based on this. • compare performance and devise event-ID (PSD & coincidence) strategies of various prototypes • devise calibration & efficiency evaluation schemes applicable to sub-keV range • measure quenching factor of Ge with neutron beam • study scale-up options ULEGe-detector • Keep other detector options open

  26. Sensitivity Plot for CDM-WIMP direct search for 100 eV threshold detector [First Results : LHB’s talk] • Low (<10 GeV) WIMP Mass / Sub-keV Recoil Energy : • Not favored by the most-explored specific models on galactic-bound SUSY-neutralinos as CDM ; still allowed by generic SUSY • Solar-system bound WIMPs require lower recoil energy detection • Other candidates favoring low recoils exist: e.g. non-pointlike SUSY Q-balls. • Less explored experimentally

  27. Quenching Factor Measurement for Ge at CIAE’s Neutron Facilities: With 13 MV Tandem • Goals for Dec 07 Runs : • Use actual ULEGe 100-eV detector • Use lower energy neutron beam with a pulsed-LE tandem

  28. p S1 S0 Detector Scale-up Plans: • 500-g, single-element, modified coaxial HPGe design, inspired by successful demonstration of Chicago group (nucl-ex/0701012) • Position-sensitive from drift-profile pulse shape • Dual-electrode readout and ULB specification • Being prepared, available first-half 2008.

  29. Road Map …… Improved PSD ; dual-readout coincidence Scale up to compact 1 kg ; understand background source (g/n) ; improved shielding design

  30. State-of-the-Art(Science) • An O[100 eV threshold1 kg mass1 cpd detector] has interesting applications in neutrino and dark matter physics, also in reactor monitoring • Open new detector window & detection channel : potentials for surprise • Mass Scale-Up: recent demonstration of realistic design • Threshold– ~300 eV at hardware level, intensive studies on software techniques to aim at ~100 eV, & on their stabilities and universalities • Prototype data at reactor already provide competitive sensitivities for WIMP search at mass<10 GeV . • Sub-keV Background understanding and suppression – under intensive studies

  31. 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 & axions • Diversified Program in Parallel Main Thrust on  ~200 kg CsI(Tl) [s(ne) …] ULEGe:for scoh(nN) + CDM Search

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