Dielectric-Boosted Sensitivity to Cylindrical Azimuthally Varying Transverse-Magnetic Resonant Modes in an Axion Haloscope
Aaron Quiskamp, Ben T. McAllister, G. Rybka, Michael E. Tobar
Abstract
Axions are a popular dark-matter candidate that are often searched for in experiments known as ``haloscopes,'' which exploit a putative axion-photon coupling. These experiments typically rely on transverse-magnetic (TM) modes in resonant cavities to capture and detect photons generated via axion conversion. We present a study of a resonant-cavity design for application in haloscope searches, of particular use in the push to higher-mass axion searches (above approximately $60\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{eV}$). In particular, we take advantage of azimuthally varying ${\mathrm{TM}}_{m10}$ modes that, while typically insensitive to axions due to field nonuniformity, can be made axion sensitive (and frequency tunable) through the strategic placement of dielectric wedges, becoming a type of resonator known as a dielectric-boosted axion-sensitivity (DBAS) resonator. Results from finite-element modeling are presented and compared with a simple proof-of-concept experiment. The results show a significant increase in axion sensitivity for these DBAS resonators over their empty-cavity counterparts and high potential for application in high-mass axion searches when benchmarked against simpler more traditional designs that rely on fundamental TM modes.