Kuo-Sheng(國聖) Reactor Neutrino Lab. Low Energy Neutrino Physics at the Kuo-Sheng Reactor Neutrino Laboratory in Taiwan TEXONO Collaboration : Overview Kuo-Sheng(國聖) Reactor Neutrino Lab. ※ Magnetic Moments Results with ULB-HPGe ※ Other topics being pursued/in preparation R&D Program Henry T. Wong / 王子敬 Academia Sinica /中央研究院 TAUP-03, Seattle

Program: Poineering Efforts : TEXONO Overview 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 possible experimentally  explore possible new detection channels R&D Projects Poineering Efforts : KS Expt: 1st particle physics experiment in Taiwan TEXONO Coll. : 1st big research Coll. % Taiwan & China [feature report in Science, Vol. 300, 1074 (2003) ]

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

KS/P1/Ge/mn : Results 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

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

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

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

“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 Threshold ~ 200 eV PSD Cut Signal Band Threshold < 100 eV

R&D Projects Upgrading FADCs (+ FPGA etc. capabilities…..) Explore New Detectors Scenarios (LEn, CDM …)  loaded crystal scintillator (GSO, YbAG, LSO …..)  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)

Also ………. Road tunnel at 2 km 100 m rock overburden Geographically possible for medium baseline experiment : 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