A significant proportion of the Universe is believed to be composed of some unknown substance known as dark matter. The leading candidate for this dark matter are weakly interacting massive particles (WIMPs). The LUX-ZEPLIN (LZ) experiment, housed one mile underground in the Sandford underground research facility (South Dakota, USA), is currently searching for these particles using a 7 tonne liquid xenon target. In this thesis the evidence for dark matter is presented alongside how liquid xenon time projection chambers are expected to detect WIMP dark matter via low energy nuclear recoils. This methodology is brought to life through LZ’s first WIMP search. This analysis, which found no WIMP candidates in its 5.5 tonne · 60 day exposure, imposes the most stringent upper limits to the spin-independant WIMP–nucleon
cross-section to date.
The calibration of the PMTs to VUV light using 83mKr is detailed alongside a comparison to previous dedicated measurements performed at Imperial. This in-situ calibration is exploited as part of a 8B sensitivity study which uses the double photoelectron emission (DPE) effect
and the time profile of xenon scintillation to reduce the scintillation threshold of LZ, improving its sensitivity to low energy interactions such as CEνNS.
Alternatively, liquid xenon (LXe) detectors can completely forgo scintillation signals in an effect to explore even lower energy phenomena. A current limitation of these “S2-only” analyses is our ability to calibrate detectors in this ultra-low energy regime. Several methods to calibrate this region using existing sources are studied assuming a 50–150 eV region of interest.
Finally, measurements of the xenon luminescence spectra are presented for warm gas, saturated vapour, and liquid states. These results, which include the first measurement of saturated xenon vapour spectra and the first simultaneous measurement of liquid and vapour spectra, observe that S1 light is consistently of longer...