Status on the Searches of Neutrino Magnetic Moment at the Kuo-Sheng Power Reactor

TL;DR

This paper reports on experimental efforts at the Kuo-Sheng Reactor to measure the neutrino magnetic moment using germanium and scintillator detectors, achieving low energy thresholds and background levels comparable to dark matter experiments.

Contribution

First experimental measurement of neutrino magnetic moment at the Kuo-Sheng Reactor with low threshold detectors and detailed background analysis.

Findings

Preliminary neutrino magnetic moment squared value: -1.1 ± 2.5 (in units of 10^{-10} μ_B)^2.

Achieved a 5 keV energy threshold with germanium detector.

Background levels comparable to underground dark matter experiments.

Abstract

The TEXONO collaboration has been built up among scientists from Taiwan and China to pursue an experimental program in neutrino and astro-particle physics. The flagship efforts have been the study of low energy neutrino physics at the Kuo-Sheng Power Reactor Plant in Taiwan. The Reactor Laboratory is equipped with flexibly-designed shieldings, cosmic veto systems, electronics and data acquisition systems which can function with different detector schemes. Data are taken during the Reactor Period June-01 till April-02 with a high purity germanium detector and 46 kg of CsI(Tl) crystal scintillator array operating in parallel. A threshold of 5 keV has been achieved for the germanium detector, and the background level comparable to those of Dark Matter experiments underground is achieved. Based on 62/46 days of analyzed Reactor ON/OFF data, a preliminary result of $\rm{(\munue / 10^{-10} \mub)^2 = - 1.1 \pm 2.5}$ can be derived for neutrino magnetic moment $\munue$. Sensitivity region on neutrino radiative decay lifetime is inferred. The complete data set would include 180/60 days of ON/OFF data.