Developments in the application of Cyclotron Radiation Emission Spectroscopy (CRES) towards the precise determination of MeV-scale β-energy spectra

Abstract

This thesis presents an apparatus for detection of cyclotron radiation yielding a frequency-based β± kinetic energy determination in the 5 keV to 2.1 MeV range, characteristic of nuclear β decays. The cyclotron frequency of the radiating β particles in a magnetic field is used to determine the β energy precisely. The He6-CRES collaboration is working towardscompetitive sensitivity to tensor currents in the weak interaction via a precise determination of b_Fierz , which parameterizes Fierz interference. This thesis presents much of the work done to complete Phase 1 of the He6-CRES experiment, whose overarching goal was to demonstrate that Cyclotron Radiation Emission Spectroscopy (CRES) can plausibly be used to achieve a 10^{−3} measurement of b_Fierz via the ratio of 6He and 19Ne spectra and to discover what experimental design, analysis, or simulation bottlenecks may hinder such a measurement. To our knowledge, this is the first direct observation of cyclotron radiation from individual highly relativistic βs in a waveguide. This work focuses on applying CRES to a precise measurement of b_Fierz but it also establishes the viability of the application of CRES to a variety of MeV-endpoint nuclei, opening its reach to searches for new physics beyond the TeV-scale via precision β-decay measurements.