ADMX System Noise Calibrations

The axion was first introduced as a solution to the strong CP problem, however it has recently gained prominence as a leading candidate for cold dark matter. There are two benchmark models describing the axion-photon coupling, DFSZ and KSVZ. While many find the DFSZ axion more compelling due to its compatibility with GUT, it is significantly more weakly coupled to photons than its counterpart, making it more difficult to detect. Notably, the Axion Dark Matter eXperiment (ADMX) was the first axion haloscope to reach sensitivity to the elusive DFSZ axion by making use of a dilution refrigerator and ultra low noise electronics. Our ability to determine how sensitive our data is, and in turn whether or not we reach this benchmark level of sensitivity, relies on a proper understanding of the noise in our receiver chain. In this talk, I will present noise calibration results from our most recent data taking run covering ~1-1.4 GHz. In particular, I will focus on the first direct measurement of the Josephson Parametric Amplifier noise achieved at ADMX, as well as how it compares to the less direct noise calibration methods we have made use of in previous data taking runs.