Search for galactic axions with a high-Q dielectric cavity

A haloscope of the QUAX–aγ experiment, composed of an high-Q resonant cavity immersed in a 8 T magnet and cooled to ∼4.5 K is operated to search for galactic axions with mass ma≃42.8 μeV, 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 Q∼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 10.35337−10.35345 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 gaγγ<0.731×10−13 GeV−1 with the confidence level set at 90%.