Cold Electronics System Design and Development for ADMX and ADMX-EFR

The Axion Dark Matter Experiment (ADMX) searches for axionic dark matter at benchmark DFSZ sensitivities. To accomplish this high sensitivity while maintaining a rapid enough scan speed to rule out large regions of parameter space, ADMX utilizes a large ~130 L microwave cavity in a 7.6 T magnetic field along with quantum-mechanical-noise-limited, cold, first stage electronics. As the experiment scans higher frequencies, corresponding to larger axion masses, the cavity diameter must decrease, lowering the detection volume and sensitivity. To counter this effect, the current G2 experiment will move to a four-cavity array above 1.4 GHz, and the extended frequency range experiment (ADMX-EFR) will utilize an eighteen-cavity array to scan from 2 to 4 GHz. Multi-cavity systems offer an exciting opportunity to search at higher frequencies, but new complexities arise in the design and operation of the system, especially the cold electronics that set the noise level of the system. In this talk, we will discuss the overall cold electronics design for the next generation experiments, along with our work developing flux pumped Josephson parametric amplifiers employing a number of novel design

features to achieve a large (1 GHz) tuning range, simplify operations, and improve noise performance.