ADMX Design and Status: Run 1C and 1C-extended

1. The Axion Dark Matter eXperiment (ADMX) uses a microwave resonant cavity design with a tunable resonant frequency to search for axions with masses on the order of 1 ??eV. The axion is a theoretical particle which was first proposed as a solution to the strong CP problem. However, its electric neutrality, weak coupling, long lifetime, and abundant production in the early universe, make it a well-motivated dark matter candidate. ADMX is the only experiment of its kind to reach sensitivity to the DFSZ model for axions. While many find this model to be more compelling than the KSVZ model, the DFSZ axion is significantly more weakly coupled to photons than its counterpart making it more elusive. To date, ADMX has excluded the range of axion-photon couplings predicted by the KSVZ (DFSZ) model for the axion between 2.66-4.2 ??eV (2.66-3.3 ??eV & 3.9-4.1 ??eV). In this talk I will discuss the instrumentation and experimental design that went into achieving this sensitivity, including the use of a dilution refrigerator and a quantum amplifier package. In particular, I will focus on our most recent data taking run, Run 1C, which searched for axions between 3.3-4.2 ??eV. Additionally, I will discuss technical upgrades that were made for Run 1C-extended, a shorter data taking run designed to close the gap in DFSZ sensitivity between 3.3-3.9 ??eV.