Search for Galactic axions with a high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Q</mml:mi></mml:math> dielectric cavity

Abstract

A haloscope of the QUAX--$a\ensuremath{\gamma}$ experiment, composed of an high-$Q$ resonant cavity immersed in a 8 T magnet and cooled to $\ensuremath{\sim}4.5\text{ }\text{ }\mathrm{K}$ is operated to search for galactic axions with mass ${m}_{a}\ensuremath{\simeq}42.8\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$, not accessible to other running experiments. The design of the cavity with hollow dielectric cylinders concentrically inserted in a OFHC Cu cavity, allowed us to maintain a loaded quality-factor $\mathrm{Q}\ensuremath{\sim}300000$ during the measurements in presence of magnetic field. Through the cavity tuning mechanism it was possible to modulate the resonance frequency of the haloscope in the region $10.35337\ensuremath{-}10.35345\text{ }\mathrm{GHz}$ and thus acquire different datasets at different resonance frequencies. Acquiring each datasets for about 50 minutes, combining them and correcting for the axion's signal estimation-efficiency, we set a limit on the axion-photon coupling ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}&lt;0.731\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ with the confidence level set at 90%.