Designing, Operating and Analyzing: The Quest for Axion Dark Matter with ADMX

Abstract

The Axion Dark Matter eXperiment (ADMX), located at the University of Washington, is a world-renowned experiment and is at the forefront of the hunt for the elusive QCD axion. The QCD axion, originally proposed in the late 1970s to solve a problem in particle physics, was quickly identified as a promising dark matter candidate. While it was initially thought to be impossible to detect due to its extremely weak coupling to standard model particles, over the past couple of decades major advancements in experimental technology have allowed experiments, like ADMX, to become sensitive enough to detect such a particle. In this thesis I will begin by providing context on the history of and evidence for dark matter, the origin of the axion as a theoretical particle, and what makes the axion a good dark matter candidate. Next, I will explain how experiments like ADMX search for axions today as well as situate ADMX in the landscape of existing and proposed axion searches. The remainder of the thesis will cover the details of the most recent data taking run with ADMX, Run 1D. More specifically I will detail the hardware changes made since the last run, the most thorough noise calibration campaign done with ADMX to date, the operations and procedures involved in taking data, as well as the full analysis process. I will finish by reporting results including a 90% confidence level upper limit on axion-photon coupling between 1.088-1.315 GHz, as well as a discussion about the discovery ability of this data set.