On Advances in LAS Instrumentation and Fiducial Volume Simulations of the S140 Detector for the NEWS-G Dark Matter Search Experiment

Abstract

NEWS-G is a direct detection dark matter experiment specializing in gas-ionization detectors called Spherical Proportional Counters (SPCs) to search for low-mass par- ticle dark matter. Principal measurement campaigns undergone by NEWS-G, pre- viously at the Laboratoire Souterrain de Modane (LSM) and currently at SNOLAB, have used a large-scale 140 cm diameter SPC called S140.This thesis will explore two studies related to the understanding of S140’s volume and gas characteristics. First, the characterization of the detector’s fiducial volume (referred to as ‘fiducialization’), defined as the volume where the detector is sensitive to signal formation, will be explored using Monte Carlo electron drift simulations. This simulation framework will be used in this thesis for the determination of limits on the effective mass acceptance of S140 during the LSM measurement campaign through the calculation of the detector’s fiducialization efficiency. A second study will also be presented looking at the feasibility of novel measurement techniques with prototype Laser Absorption Spectroscopy (LAS) apparatuses in the live measurement of the concentration of CH4 within S140.