A Search for Dark Photon Dark Matter with ADMX-Orpheus*

Dark matter makes up 85% of the matter in the universe and 27% of its energy density, but we don't know what comprises dark matter. Several compelling candidates for dark matter have wavelike properties, including axions and dark photons. Wavelike dark matter can be detected using ultra-sensitive microwave cavities. The ADMX experiment uses a cylindrical cavity operating at the fundamental mode to search for axions in the few micro-eV mass range. However, this technique becomes increasingly challenging with increasing axion mass. Higher masses require smaller cavities, which reduces the signal strength. Thus, there is interest in developing more sophisticated resonators to overcome this problem. The ADMX-Orpheus experiment uses a dielectric-loaded Fabry-Perot cavity to search for axions and dark photons with masses approaching 100 micro-eV. Orpheus maintains a large volume by operating at a higher-order mode, and the dielectrics shape the electric field so that the mode couples more strongly to axions and dark photons. This poster describes the development, commissioning, and results of ADMX-Orpheus to search for dark photons with masses between 65.5 micro-eV and 69.3micro-eV, as well as future directions for axion searches and for exploring more parameter space.