Physics Program of TEXONO: Highlights TEXONO Overviews Kuo-Sheng Reactor Neutrino Laboratory  Results on Neutrino Magnetic Moment  Other Analysis Subjects being Pursued  Present Status and Plans R&D Program Henry T. Wong / 王子敬 Academia Sinica / 中央研究院 @ IHEP + CIAE September 2003

Congratulations to 2003 TEXONO Degrees Ph.D.s : Yue Qian 岳骞, IHEP (now at THU) Xin Biao 辛標, CIAE (remains at CIAE) M.Sc : Liu Da-Zhi 劉大治, THU (now at MIT)

Poineering Efforts : “Zero-Background Experiment” ! TEXONO Overview Program: Kuo-Sheng Reactor Neutrino Laboratory ※ reactor : high flux of low energy electron anti-neutrinos ※ 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 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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TEXONO* Collaboration W.C. Chang¶, K.C. Cheng, M.H. Chou, C.H. Iong, G.C. Jon, F.S. Lee, S.C. Lee, H.B. Li, D.L. Lin, F.K. Lin, S.T. Lin, 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, J.M. Huang, W.S. Kuo, T.R. Yeh Institute of Nuclear Energy Research, Lungtan, Taiwan M.Z. Wang¶ National Taiwan University, Taipei, Taiwan J.H. Chao, J.H. Liang National Tsing Hua University, Hsinchu, Taiwan Z.M. Fang, R.F. Su Nuclear Power Station II, Kuosheng, Taiwan J. Bao, M. He, 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, Z.P. Mao, J. Nie, J.F. Qiu, H.Y. Sheng, P.L. Wang, X.W. Wang, D.X. Zhao, J.W. Zhao, P.P. Zhao, S.Q. Zhao, B.A. Zhuang Institute of High Energy Physics, Beijing, China Z.S. Liu, Z.Y. Zhang Institute of Radiation Protection, Taiyuan, China T.Y. Chen Nanjing University, Nanjing, China J.P. Cheng, 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. † Co-Prinicipal Investigators ¶ Project Leaders Ph.D. Students *Taiwan EXperiement On NeutrinO Home Page @ http://hepmail.phys.sinica.edu.tw/~texono/ 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.

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

ULB-HPGe + Anti-Comptons KS Expt. : Period I Configuration Period I : June 01 – April 02 (60 days OFF) Shielding & Veto [one side] ULB-HPGe + Anti-Comptons CsI(Tl) Array (46 kg)

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]

mn with Reactor ne mn Experimental Probe:  parametrize possible niL njR + g vertices   both i = j “diagonal” & i  j “transition” moments Experimental Probe:  Study ne + e-  nX + e-  Focus on low recoil energy ※ sm  T–1 ※ decouples SM “background” [ ……… LE reactor f(ne) not accurately known]  Look for Excess in Reactor ON/OFF Neutrino Radiative Decay (Gn):  sm & Gn related:  same vertices – real g for Gn Electron Recoil Spectra

PDG Limit : 1.5 X 10-10 mB (indirect seach from SK spectral shape) an allowed solution for the solar neutrino data (before KamLAND)

KS/P1/Ge : Spectra & Residual Based on 196/52 days of Reactor ON/OFF data No anomalous structures or residuals

KS/P1/Ge/mn : Results (LHB Thesis) Total 4712/1250 hours ON/OFF  No residual observed Range of O(1 cpd) background c/f Dark Matter expt. Fit OFF spectra to p5 Measure [fOFF;dfOFF ] (@ c2/dof = 80/96 ) Fit ON spectra to fOFF + fSM + k2 fMM [10-10 mB] Fit Results (@ c2/dof = 48/49 ): k2 = -0.4  1.3 (stat.)  0.4 (sys.) Limits derived : mn < 1.3 (1.0)  10-10 mB @ 90(68)% C.L. H.B. Li et al., TEXONO Coll., Phys. Rev. Lett. 90, 131802 (2003)

Reactor mn(ne) Sensitivities Gn Sensitivities

Kuo Sheng Reactor Neutrino Laboratory : First Results

Citation in AIP’s Physics News Update : 2003 Related websites Physics News Graphics Physics News Links American Institute of Physics Online Journal Publishing Service Back to Physics News Update Number 631 #1, April 2, 2003 by Phil Schewe, James Riordon, and Ben Stein The First-Ever Large China-Taiwan Scientific Collaboration The first-ever large China-Taiwan scientific collaboration has carried out a reactor experiment which puts a new upper limit on the neutrino magnetic moment. Consider first the electron; it not only has electrical charge but also spin, which means that it will act like a tiny magnet. Even a neutral atom, because of its internal distribution of negative and positive charge, can have a nonzero magnetic moment. Consequently neutral atoms can be controlled, to some extent, by magnetic fields. But what about a neutrino? Neutrinos may well possess a small amount of mass, But what about magnetism? Can they effectively have a tiny bit of charge or internal structure? A nonzero neutrino magnetic moment provides the neutrino with a way to interact electromagnetically with the world; generally the neutrino is thought to interact only via the weak nuclear force. Evidence for nonzero magnetic moment would show up in several ways: in anomalous electron-neutrino scattering, in radiative decays in which the neutrino casts off a gamma ray, and in various astronomical settings, such as supernovas. The TEXONO collaboration, using neutrinos from the 2.9-GW Kuo-Sheng Nuclear Power Station in Taiwan, looked for a characteristic anomalous electron energy spectrum arising from electron-neutrino scattering. They did not see any such evidence, and from this they derive the best direct-laboratory upper limit on neutrino magnetic moment, 1.3 x 10-10 times the magnetic moment of the electron (a unit also known as the Bohr magneton). The team also derives an indirect bound on neutrino radiative decays. (Li et al., Physical Review Letters, 4 April 2003; contact Henry Wong, Academia Sinica, Taiwan, 886-2-2789-6789) The TEXONO Collaboration is supported by several research institutions and their respective funding agencies from Taiwan and China. An efficient flow of students and scientists moves in both directions. Back to Physics News Update  

Doppel-Null Neutrino bleibt unmagnetisch                            Dienstag, 15.4.2003                                                                                                                                                                                                                                                                                                                                      Doppel-Null Neutrino bleibt unmagnetisch Auch Nicht-Ergebnisse liefern Physikern Einsichten – zum Beispiel der Versuch, an Neutrinos ein magnetisches Moment zu messen. Ein solches Moment kann theoretisch auch bei neutralen Teilchen wie Neutrinos entstehen, wenn eine Eigendrehung die negativen und positiven Ladungsanteile herumwirbelt. Deshalb suchten die Forscher nach subtilen Abweichungen von der – ohnehin extrem schwachen – Wechselwirkung von Neutrinos aus einem Kernreaktor mit Elektronen. Ihr Resultat: Null, wie bei früheren Experimenten. Allerdings haben sie die Null genauer vermessen; die Fehlergrenze liegt etwa beim zehnmilliardsten Teil des magnetischen Moments des Elektrons ( Physical Review Letters, Bd.90, Nr.131802, 2003). Somit hält sich das Neutrino an die etablierte Theorie: Die elektromagnetische Wechselwirkung lässt es völlig kalt. Wärmer wurde hingegen das Verhältnis der beteiligten Forscher. Sie stammten aus der Volksrepublik China und aus Taiwan.

科學人雜誌 (Scientic American/Chinese) 2003年5月號

Prototype ULE-HPGe [5 g] : Status & Plans HPGe [1 kg] : mn + Gn : x2 more data improved background & analysis study ne flux from reactor dominated by 51Cr : ~ 10-3 (prelim.) study possible nuclear transitions e.g. 73Ge* decays by 2g’s separated by t1/2=4.6 ms 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 P2: SM (ne) > 2 MeV P1: MM (ne) 1-100 keV P3+: Coh. (nN) < 1 keV

Reactor as ne Source (Xin Biao’s Thesis) Fission Material Fission Products Neutrons odd-odd nuclei Structural materials of reactor Electron capture or + decay ( neglected ) νe Emission Captured Mostly rich in neutrons ¯ Decay back to  stable valley Anti-neutrino Emisson

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 the transition To look for : possible n-induced nuclear transitions

CsI(Tl) Array : Highlights 40 cm length (longest commercial prod.) Energy+3D info:  10% FWHM at 660 keV  s(z) <2 cm @ E>250 keV Intrinsic Detector Threshold ~ 20 keV PSD for g/a : > 99% Intrinsic Purity :  238U/232Th < 10-12 g/g (equil.)  40K < 10-10 g/g Status: 186 kg target on-site for Period-II DAQ with large dynamic range

Period-2 CsI(Tl) Array : 186 kg, 93 crystals Single Crystal QL Vs QR (Raw Data) Region of Interest for SM s(ne)

KS/P2: 93-Element CsI(Tl) Array (to be optimized)

137Cs contamination in CsI ~556 events/day/kg Background Spectra (with all cuts; 1 module/ 2 kg ; about 1 week ; NOT fully optimized yet ) 137Cs contamination in CsI ~556 events/day/kg ==> 2.3 X 10-18 g/g (prelim.)

“Ultra-Low-Energy” HPGe Prototype mass 5 g ; can be constructed in multi-array form 55Fe+Ti back-scattered Spectra : noise edge at 200 eV threshold <100 eV after modest PSD background measurement on-site Oct 03 study appl. in nN coherent scattering and Dark Matter searches

ULE-HPGe Prototype Results Threshold ~ 200 eV PSD Cut Signal Band Threshold < 100 eV

R&D Projects Upgrading FADCs (+ FPGA etc. capabilities…..) Explore New Detectors Scenarios (LEn, CDM …)  other crystal scintillators  ultra low energy HPGe [ O(100 eV) threshold ] CsI(Tl) for Dark Matter Searches  CsI(Tl) CDM search @ 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)

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 Program: 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. (apprd.) :  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) Sensitivity goal : 10-14 g/g Future :  different bases e.g. liquid scintillator  87Rb …… [238U / 232Th series after Tandem upgrade]

Sonoluminescence Project a frontier subject with possible surprises new directions : to explore subjects we do not know Table-top experiments, pursue-able in several labs  balance the other big & long time-scale projects  use HEP approaches Status :  produce steady SL  integrate DAQ  study physics  identify research topics …….. SL Typical Cycle SL Typical Set-Up

SonoLum Pulse

Also ………. Road tunnel at 2 km 100 m rock overburden Geographically possible for medium baseline experiment for “ q13 ’’ search : Easy reach from city Access to Plant established Road tunnel at 2 km 100 m rock overburden

Summary & Outlook TEXONO Collaboration:  Built-Up and 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 DAQ  Improved HPGe Conf.  186 kg CsI(Tl) [s(ne) …]  study potentials for scoh(nN) …… Diversified R&D Program in parallel

TEXONO at present is rather like .............. Thank You for Making This Happen !!!! Hope WE can further Achieve Higher Grounds Together !