# Galactic axions search with a superconducting resonant cavity

## TL;DR

This paper reports a search for galactic axions using a superconducting NbTi cavity at 9 GHz, achieving a high quality factor that enhances sensitivity, and sets new limits on axion-photon coupling around 37 μeV.

## Contribution

The study demonstrates the use of a superconducting NbTi cavity to improve axion search sensitivity at higher frequencies, overcoming limitations of traditional copper cavities.

## Key findings

- Achieved a quality factor of 4.5×10^5 at 9 GHz with NbTi cavity.
- Set a limit on axion-photon coupling: g_{aγγ} < 1.03×10^{-12} GeV^{-1} at 37 μeV.
- Provided a detailed analysis of NbTi cavity performance under various conditions.

## Abstract

To account for the dark matter content in our Universe, post-inflationary scenarios predict for the QCD axion a mass in the range $(10-10^3)\,\mu\mbox{eV}$. Searches with haloscope experiments in this mass range require the monitoring of resonant cavity modes with frequency above 5\,GHz, where several experimental limitations occur due to linear amplifiers, small volumes, and low quality factors of Cu resonant cavities. In this paper we deal with the last issue, presenting the result of a search for galactic axions using a haloscope based on a $36\,\mbox{cm}^3$ NbTi superconducting cavity. The cavity worked at $T=4\,\mbox{K}$ in a 2\,T magnetic field and exhibited a quality factor $Q_0= 4.5\times10^5$ for the TM010 mode at 9\,GHz. With such values of $Q$ the axion signal is significantly increased with respect to copper cavity haloscopes. Operating this setup we set the limit $g_{a\gamma\gamma}<1.03\times10^{-12}\,\mbox{GeV}^{-1}$ on the axion photon coupling for a mass of about 37\,$\mu$eV. A comprehensive study of the NbTi cavity at different magnetic fields, temperatures, and frequencies is also presented.