Measurement of neutrino-electron scattering cross section and the EW parameters at the Kuo-Sheng reactor neutrino laboratory

The ν-bare-e- elastic scattering cross-section was measured at the Kuo-Sheng Nuclear Power Station with a CsI(Tl) scintillating crystal detector array with a total mass of 187 kg. The detector was exposed to a reactor ν-bare flux of 6.4 x 1012 cm-2s-1 originated from a core with 2.9 GW thermal power. A cross-section ratio of Rexpt = [1.08 ± 0.21 (stat) ± 0.16 (sys)] x RSM was measured. Constraints on the electroweak parameters (gv,gA) were placed, corresponding to a weak mixing angle measurement of sin2θw = 0.251 ± 0.031 (stat) ± 0.024 (sys). The destructive interference in the SM ν-bar e-e processes was verified with the value of RINTexpt = [0.92 ± 0.30 (stat) ± 0.24 (sys)] x RINTSM. Bounds on neutrino anomalous electromagnetic properties were placed: neutrino magnetic moment at μν-bar e < 2.2 x 10-10μB at 90% C. L., and the neutrino charge radius at = [0.61 ± 1.30 (stat) ± 1.01 (sys)] x 10-32 cm2.