Superconducting Resonator Development for the Axion Dark Matter eXperiment

Abstract: The Axion Dark Matter eXperiment (ADMX) is the first axion haloscope search to reach DFSZ sensitivity in any mass range for the QCD axion. The QCD axion is a well-motivated dark matter candidate that additionally solves the strong CP problem in nuclear physics. A haloscope has three necessary components; a very strong external magnet, a high Q cavity resonator embedded in this field, and an ultra-sensitive RF read-out system. This dissertation mainly reports on the future development of the resonators for ADMX, specifically superconducting RF (SRF) cavities. It starts with an overview of axions, haloscopes, and the current ADMX experiment, followed by the work done at Lawrence Livermore National Laboratory (LLNL) on SRF cavities, and finally the preliminary results of the ADMX "hybrid" superconducting-copper Sidecar cavity in run 1D.