High-Quality-Factor Superconducting Cavities in Tesla-Scale Magnetic Fields for Dark-Matter Searches

Abstract

In dark-matter searches using axion haloscopes, the search sensitivity depends on the quality factors (Q0) of radio-frequency cavities immersed in multitesla magnetic fields. Increasing Q0 would increase the scan rate through the parameter space of interest. Researchers developing superconducting radio-frequency cavities for particle accelerators have developed methods for obtaining extremely high Q0 of approximately 1011 in microteslascale magnetic fields. In this paper, we describe efforts to develop high-Q cavities made from Nb3Sn films using a technique developed for particle-accelerator cavities. Geometry optimization for this application is explored, and two cavities are tested: an existing particle-accelerator-style cavity and a geometry developed and fabricated for use in high fields. A quality factor of (5.3±0.3)×105 is obtained at 3.9 GHz and 6 T at 4.2 K.