File:Thesis LeoS.pdf

Summary

Commissioning the chopping wheel upgrade to VULCAN, and identifying sources of noise in photoluminescence decay measurements. Abstract:

Dark matter direct detection experiments, such as XENONnT and LUX-ZEPLIN, rely on highly sensitive dual-phase Xenon Time Projection Chambers (XeTPCs). Unexplained lone S1 signals in these detectors may stem from delayed background sources, such as photoluminescent contaminants. This research commissions an upgrade to the Vacuum Ultraviolet Light Characterization At Nikhef (VULCAN) setup, allowing for time-resolved photoluminescence measurements via the addition of an optical chopping wheel. Two types of solder flux, Stannol’s KS115 and Chemtronic’s CW8400, were used as photoluminescent samples as they are used in the XENONnT and LUX-ZEPLIN detectors respectively. The solder flux samples were illuminated with 161~nm VUV light, and their photoluminescence decay was monitored using Silicon Photomultipliers (SiPMs). While both solder fluxes demonstrated photoluminescent emission under 161 nm excitation, the data revealed significant sources of instrumental noise. Specifically, two optical background signals were identified and partially characterized: a secondary peak off in phase by half a period from the photoluminescent response and a 200~Hz harmonic noise, both likely originating from the chopping wheel's phase detector LED. Ultimately, this study successfully commissions VULCAN's time-resolved capabilities and establishes the analytical pipeline necessary to extract the photoluminescence lifetimes of the fluxes once the identified optical noise is shielded.