Kuo-Sheng(國聖) Reactor Neutrino Lab. A Search of Neutrino Magnetic Moment at the Kuo-Sheng Power Plant in Taiwan TEXONO Collaboration : Overview Kuo-Sheng(國聖) Reactor Neutrino Lab. ※ Magnetic Moments Results with ULB-HPGe Other Physics, Status and Plans Hau-Bin Li / 李浩斌 Academia Sinica /中央研究院 @ EPS03, Aachen
Program: Achieved : TEXONO Overview Kuo-Sheng Reactor Neutrino Laboratory ※ reactor : high flux of low energy electron anti-neutrinos ※ mn0 anomalous n properties & interactions ※ n physics full of surprises study/constraint new regime wherever possible experimentally explore possible new detection channels R&D Projects Achieved : 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 Data Data Volume: HPGe Performance: Analysis: Total 4712/1250 hours ON/OFF HPGe Performance: 1.06 kg mass 0.4 keV RMS @ 10 keV 5 keV detector threshold [Unique Data] Range of O(1 cpd) [counts kg-1 day-1 keV-1] background c/f Dark Matter expt. Analysis: Cosmic Veto (5 ms gate) Anti-Compton (Well+Base detectors) Pulse Shape Disc. (veto elect. noise, accidentals) Efficiencies Normalization: (to <0.2%) DAQ book-keeping Monitor random triggers Monitor residual 40K peaks Monitor 10 keV Ga X-rays peak
Cosmic Veto, Anti-Compton & PSD Events correlated to Cosmic No signal in Anti-Compton detectors PSD : Events Selected
KS/P1/Ge/mn : Results 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 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 explore potentials on nN coherent scattering
Reactor Neutrino Interaction Cross-Sections P2: SM (ne) > 2 MeV P1: MM (ne) 1-100 keV P3+: Coh. (nN) < 1 keV
Summary TEXONO Collaboration: Kuo-Sheng Neutrino Lab.: 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) …] Diversified R&D Program in parallel