3D Lumped LC Resonators as Low Mass Axion Haloscopes

TL;DR

This paper proposes using 3D lumped LC resonators, specifically re-entrant cavities, as low-mass axion haloscopes, potentially enabling detection in previously unexplored frequency ranges with enhanced sensitivity.

Contribution

It introduces a novel application of 3D lumped LC resonators as axion detectors, expanding the accessible mass range for dark matter searches.

Findings

Designs geometries to maximize axion coupling in re-entrant cavities.

Calculates sensitivity and frequency range for low-mass axion detection.

Demonstrates potential to explore unsearched axion mass regions.

Abstract

The axion is a hypothetical particle considered to be the most economical solution to the strong CP problem. It can also be formulated as a compelling component of dark matter. The haloscope, a leading axion detection scheme, relies on the conversion of galactic halo axions into real photons inside a resonant cavity structure in the presence of a static magnetic field, where the generated photon frequency corresponds to the mass of the axion. For maximum sensitivity it is key that the central frequency of the cavity mode structure coincides with the frequency of the generated photon. As the mass of the axion is unknown, it is necessary to perform searches over a wide range of frequencies. Currently there are substantial regions of the promising pre-inflationary low mass axion range without any viable proposals for experimental searches. We show that 3D resonant LC circuits with separated magnetic and electric fields, commonly known as re-entrant cavities, can be sensitive dark matter haloscopes in this region, with frequencies inherently lower than those achievable in the equivalent size of empty resonant cavity. We calculate the sensitivity and accessible axion mass range of these experiments, designing geometries to exploit and maximize the separated magnetic and electric coupling of the axion to the cavity mode.