Discrimination in Liquid Xenon and Calorimetry in Superfluid Helium for the Direct Detection of Particle Dark Matter
In this dissertation, we present several recent developments in instrumentation for dark matter detectors. The liquid/gas two-phase xenon time projection chamber is well-established as an excellent technology to search for Weakly Interacting Massive Particles (WIMPs). We present analyses of data from the Large Underground Xenon (LUX) and Particle Identification in Xenon at Yale (PIXeY) experiments, in which we study signal vs. background discrimination as a function of detector parameters. This informs design decisions for current and future xenon detectors. Then, we focus on cutting-edge calorimetric technologies geared towards searches at the MeV/c^2 scale. We present measurements of the superconducting transition of several materials, and we discuss their potential use as transition-edge sensors (TES). Helium as a detection target with TES signal readout is explored, and its sensitivity to dark matter-induced nuclear recoils is calculated.