First results of the CAST-RADES haloscope search for axions at 34.67 $\mu$eV

TL;DR

This paper reports the first results from the CAST-RADES haloscope, a novel detector for axion dark matter at 34.67 μeV, setting new exclusion limits and demonstrating the potential for broader mass range exploration.

Contribution

The work introduces a new resonant cavity design within the CAST experiment, achieving improved sensitivity and establishing a methodology for future wider mass range axion searches.

Findings

Set a new exclusion limit on axion-photon coupling at 34.67 μeV

Demonstrated the feasibility of using coupled sub-cavities in axion detection

Achieved sensitivity surpassing previous CAST limits at this mass

Abstract

We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part of the CERN Axion Solar Telescope (CAST), searching for axion dark matter in the 34.67$\mu$eV mass range. A radio frequency cavity consisting of 5 sub-cavities coupled by inductive irises took physics data inside the CAST dipole magnet for the first time using this filter-like haloscope geometry. An exclusion limit with a 95% credibility level on the axion-photon coupling constant of g$_{a\gamma}\gtrsim 4\times10^{-13} \text{GeV}^{-1}$ over a mass range of 34.6738 $\mu$eV < $m_a$ < 34.6771 $\mu$eV is set. This constitutes a significant improvement over the current strongest limit set by CAST at this mass and is at the same time one of the most sensitive direct searches for an axion dark matter candidate above the mass of 25 $\mu$eV. The results also demonstrate the feasibility of exploring a wider mass range around the value probed by CAST-RADES in this work using similar coherent resonant cavities.