First characterisation of the MAGO cavity, a superconducting RF detector for kHz-MHz gravitational waves

TL;DR

This paper characterizes a superconducting RF cavity developed for high-frequency gravitational wave detection, providing essential data for future cryogenic experiments and cavity design improvements.

Contribution

It presents the first detailed mechanical and electromagnetic characterization of a MAGO cavity, informing future high-frequency gravitational wave detection efforts.

Findings

Mechanical and electromagnetic resonance data obtained

Room-temperature tuning achieved despite fabrication deviations

Insights gained for future cryogenic and design improvements

Abstract

Heterodyne detection using microwave cavities is a promising method for detecting high-frequency gravitational waves or ultralight axion dark matter. In this work, we report on studies conducted on a spherical 2-cell cavity developed by the MAGO collaboration for high-frequency gravitational waves detection. Although fabricated around 20 years ago, the cavity had not been used since. Due to deviations from the nominal geometry, we conducted a mechanical survey and performed room-temperature plastic tuning. Measurements and simulations of the mechanical resonances and electromagnetic properties were carried out, as these are critical for estimating the cavity's gravitational wave coupling potential. Based on these results, we plan further studies in a cryogenic environment. The cavity characterisation does not only provide valuable experience for a planned physics run but also informs the future development of improved cavity designs.