A measurement of the $e$-$\bar{\nu_e}$ angular correlation coefficient in the decay of $^6$He

Abstract

A measurement of the beta-neutrino angular correlation coefficient $a_{\beta\nu}$ in the pure Gamow-Teller $\beta^-$ decay of $^6$He has been performed to the level of $2.2\%$ in order to search for exotic tensor-type interaction terms in the electro-weak sector of the Standard Model. The experiment involves the production and trapping of $^6$He in a magneto-optical trap and measurement of the $^6$Li$^+$ recoil ion time-of-flight spectrum in coincidence with the $\beta$ using a scintillator, a multi-wire proportional chamber, and microchannel plate detectors. The analysis of the data and systematic uncertainties is conducted using a Monte-Carlo simulation. This dissertation describes the developments and calibrations for the electric field, the chamber and trap geometries, and the detector timing systems of this experiment, along with the development of the ion tracking module and electromagnetic field map solutions used in the Monte-Carlo simulation. The measurement of $a_{\beta\nu}$ is based on data acquired with the setup in June 2017.