Results from ADMX 'hybrid-superconducting' Sidecar

The Axion Dark Matter eXperiment (ADMX) was the first axion haloscope to search for axions at DFSZ sensitivity in any mass range of the invisible axion. The invisible axion is a well-motivated dark matter candidate that additionally solves the strong CP problem in nuclear physics. ADMX Sidecar is an additional high frequency haloscope experiment that resides within the ADMX-main insert, making use of extra space within the main experiment’s cryostat and magnetic field region. Sidecar has been used to test novel axion haloscope technologies within an actual axion search context. Although it is not KSVZ or DFSZ-sensitive, Sidecar has excluded Axion-Like Particles (ALPs) in variety of axion mass regions ranging from 17-30 µeV. Sidecar data runs have employed novel hardware such as piezoelectric motors, Josephson Travel-Wave Parametric Amplifiers (JTWPAs), and most recently a Nb₃Sn superconductor-coated tuning rod. This presentation reports on the data-taking run that deployed this superconducting tuning rod, and the characterization of this ‘hybrid’ Nb₃Sn-Cu cavity system. Additionally, novel analysis procedures were implemented to increase axion sensitivity, and characterize the receiver system noise.