High-mass axion search with a dielectrically loaded Fabry Perot cavity

Orpheus is a resonant axion haloscope which uses a novel cavity design with dielectrics to search for axions with masses around 70 μeV. Currently, most axion haloscopes use a closed resonant cavity design with a tunable frequency to enhance the axion signal. However, haloscopes employing a closed cylindrical cavity are limited to lower frequencies due to the signal power being proportional to the cavity volume. Orpheus uses dielectrics in an open cavity to couple a high order resonant mode of the cavity to the axion field, and thus achieves an effective volume which is roughly 20 times greater than that of a closed cylindrical cavity at the same frequency. The Orpheus cavity design allows for a simple mechanism for tuning its resonant frequency, and it is sensitive to axions between roughly 65-70 μeV, corresponding to resonant frequencies of around 15.8-16.8 GHz. A dark photon search has already been conducted and the results of that search have been published. Since then, the Orpheus magnet has been constructed at the University of Washington. In this talk we will be presenting results from our first axion search, which will take place this winter.