Measurement of Neutrino-Electron Scattering Cross-Section with a CsI(Tl) Scintillating Crystal Array at the Kuo-Sheng Nuclear Power Reactor

Abstract

The ${\bar{\nu }}_e-e^{-}$ elastic scattering cross-section was measured with a CsI(Tl) scintillating crystal array having a total mass of 187kg. The detector was exposed to an average reactor ${\bar{\nu }}_e$ flux of $6.4\times 10^{12}\mathrm{c}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$ at the Kuo-Sheng Nuclear Power Station. The experimental design, conceptual merits, detector hardware, data analysis and background understanding of the experiment are presented. Using 29882/7369 kg-days of Reactor ON/OFF data, the Standard Model(SM) electroweak interaction was probed at the squared 4-momentum transfer range of ${\mathrm{Q}}^2\sim 3\times 10^{-6}\mathrm{Ge}{\mathrm{V}}^2$. The ratio of experimental to SM cross-sections of $\xi =[1.08\pm 0.21(stat)\pm 0.16(sys)]$ was measured. Constraints on the electroweak parameters $(g_V,g_A)$ were placed, corresponding to a weak mixing angle measurement of $ \s2tw = 0.251 \pm 0.031({\it stat}) \pm 0.024({\it sys}) $. Destructive interference in the SM $\nuebar -$e process was verified. Bounds on anomalous neutrino electromagnetic properties were placed: neutrino magnetic moment at $μ_{\nuebar}< 2.2 \times 10^{-10} μ_{\rm B}$ and the neutrino charge radius at $-2.1 \times 10^{-32} ~{\rm cm^{2}} < \nuchrad < 3.3 \times 10^{-32} ~{\rm cm^{2}}$, both at 90% confidence level.

18 Figures, 7 Tables; published version as V2 with minor revision from V1