ORCID

0000-0002-6914-3793

Date of Award

Fall 2025

Language

English

Embargo Period

10-21-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Physics

Program

Physics

First Advisor

Matthew Szydagis

Committee Members

Cecilia Levy, Jonathan Petruccelli, Kevin Knuth, Teal Pershing

Keywords

Dark Matter, Physics, LUX-ZEPLIN

Subject Categories

Other Physics

Abstract

The full understanding of dark matter has eluded physicists for many years. While there is abundant astrophysical evidence across many scales, the exact nature of this matter, which comprises about 25% of the Universe’s energy density, remains unknown. Weakly Interacting Massive Particles (WIMPs) are one of the leading theoretical candidates, and numerous ex- periments have searched for their interactions. In recent decades, dual-phase Time Projection Chambers (TPCs) have become the leading technology in this search. The LUX-ZEPLIN (LZ) detector is one such xenon-based experiment, operating nearly a mile underground in the Black Hills of South Dakota at the Sanford Underground Research Facility (SURF). LZ contains 7 tonnes of active liquid xenon, of which about 5.5 tonnes comprise the central target within the TPC. Incoming radiation produces two signals: a prompt scintil- lation (S1) and a delayed electroluminescence (S2). By combining these two observables, LZ can reconstruct event energy and position with high precision and discriminate between signal and background. In addition to its flagship S1+S2 WIMP search, LZ also enables specialized analyses that extend its reach and refine its calibration framework. The first focus of this thesis is an S2-only analysis, which forgoes the S1 signal entirely to extend sensitivity to lower- energy depositions and lighter dark matter candidates. This approach introduces unique challenges, particularly from cathode-related backgrounds that cannot be rejected without drift-time information. My work develops data-driven methods to estimate these background rates and evaluates the efficiency of event selection cuts. The second focus of this thesis is a Doke plot analysis, which employs monoenergetic calibration sources to measure the detector gains g1 (light collection) and g2 (charge am- plification). These parameters underpin the conversion of observed signals into a common energy scale and are essential for all LZ science analyses. Here, we perform the traditional Doke analysis, extend it to include monoenergetic alpha peaks, study time-binned behavior relative to detector operational conditions, and analyze individual ER calibration sources. Together, these studies broaden LZ’s discovery reach and refine its calibration accuracy, enhancing the experiment’s overall sensitivity to rare dark matter interactions.

License

This work is licensed under the University at Albany Standard Author Agreement.

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