The TEXONO Research Program on Experimental Neutrino & Astroparticle Physics

1. Henry T. Wong / 王子敬 Academia Sinica / 中央研究院 @ 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 April 2005

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

3. 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

4. Particle Physics ※(ni)L – (nj )R – g vertices described in general by: • eijand 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

5. 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 • …………

6. Astrophysics Bounds/Indications From: • Big Bang Nucleosynthesis degree of freedom • Stellar Cooling via • Cooling of SN1987a vianactive nsterile • Absence of solar [KamLAND-03 < 2.8x10-4 ; n04: HE eventsstay tuned] ranges of mn(astro) < 10-10 – 10-12mB 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 ……)

7. 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 – 10-12mB (after Bmodeling)

8. 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 fornD/nM & diag./tran. moments--no modeling involved • interpretation of results : need totake into account difference in |n>initial

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

10. 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 10-7mB (90% CL)

11. 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

12. 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 10-10mB (90% CL) • Visual scan T > 900 keV mn(ne) < 1.0 X 10-10mB (90% CL) • Auto scan T > 300 keV mn(ne) < 1.7 X 10-10mB (90% CL) • studies of hidden n-sourcesand/or low energy background necessary

13. 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

14. TEXONO Research Program ………...

15. 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.

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

19. 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

20. 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]

21. Kuo Sheng Reactor Neutrino Laboratory : First Results

22. 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

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

24. 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 10-10mB (90% CL) • more data/improvement to get to sensitivity range mn(ne) 1.0 X 10-10mB

25. Reactor mn(ne) Sensitivities Gn Sensitivities

26. Coverage in International Press

27. 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:

28. 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

29. 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

30. Period II Installation – HPGe

31. 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

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

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

34. Exclusion Plot for ne Radiative Decays:

35. 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

36. 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

37. “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

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

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

40. 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

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

42. 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

43. R&D Projects • Explore New Detectors Scenarios (LEn, CDM …) • other crystal scintillators (GSO …) • ultra low energy HPGe [ O(100 eV) threshold ] • Feasibility Studies onCsI(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-LuminescenceProject (inter-disciplinary) Completed On-Going Completed Completed On-Going On-Going

44. 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 NKIMS Expt. :  200 kg CsI(Tl) for CDM in S. Korea

45. 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)

46. 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 =====

47. CIAE-AMS system

48. 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

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

50. SonoLum Pulse