Echo-free quality factor of a multilayer axion haloscope

TL;DR

This paper introduces a method to measure the quality factor of a multilayer dielectric haloscope for dark matter detection, demonstrating a prototype with enhanced sensitivity to axions in the GHz frequency range.

Contribution

It presents a novel methodology for determining the quality factor in dielectric haloscopes and demonstrates a prototype with improved sensitivity to axions.

Findings

A new measurement technique for Q-factor in dielectric haloscopes.

Prototype sensitivity to axions with coupling constants as low as 10^{-14} GeV^{-1}.

Projected full-scale DALI sensitivity reaches coupling constants of a few times 10^{-15} GeV^{-1}.

Abstract

We report a methodology to determine the quality factor ($Q$) in implementations of the so-called dielectric haloscope, a new concept of wavy dark matter detector equipped with a multilayered resonator. An anechoic chamber enables the observation of the resonance frequency and its amplitude for an unlimited series of layers for the first time, which is conveniently filtered. The frequency-normalized power enhancement measured in a Dark-photons \& Axion-Like particles Interferometer (DALI) prototype is a few hundred per layer over a sweep bandwidth of half a hundred MHz. In light of this result, this scaled-down prototype is sensitive to axions saturating the local dark matter density with a coupling to photons between $g_{a\gamma\gamma}\gtrsim10^{-12}$ GeV$^{-1}$ and $g_{a\gamma\gamma}\gtrsim$ few $\times 10^{-14}$ GeV$^{-1}$ at frequencies of several dozens of GHz once cooled down to the different working temperatures of the experiment and immersed in magnetic fields ranging from 1 T to 10 T; while the sensitivity of the full-scale DALI is projected at $g_{a\gamma\gamma}\gtrsim\mathrm{few}\times10^{-15}$ GeV$^{-1}$ over the entire 25--250 {\mu}eV range since $Q\gtrsim10^4$ is expected.