Horn-array haloscope for volume-efficient broadband axion searches

Abstract

The invisible axion is a hypothetical particle that arises from the Peccei-Quinn mechanism proposed to resolve the CP problem in quantum chromodynamics, and is considered one of the most favored candidates for cold dark matter. Dish antennas can provide a useful scheme for sensitive searches for dark matter axions. The conversion power through axion-photon couplings is proportional to the surface area of the metal plate, rather than the volume of the available magnetic field. To maximize the effect, we propose an advanced concept of haloscope that involves an array of horn antennas to increase the axion-induced photons and a reflector to focus them onto a photo sensor. Compared with other proposed schemes, this configuration can significantly improve the experimental sensitivity, especially in the terahertz region.