Searching for Dark Photons with a room-temperature dielectric haloscope

Abstract

We present a search for dark-photon dark matter with a room-temperature dielectric multilayer haloscope. The dielectric stack enhances photon conversion near 2 eV, and a spatially resolved CMOS focal plane records the emitted photons with few-photon sensitivity. We calibrate the stack-lens-CMOS response in situ and use the calibrated focal-plane pattern in a template-based inference. With 904 h of search data and 404 h of background-control data, we observe no excess and set a 90% confidence-level upper limit of $κ< 4.0\times10^{-13}$ for dark-photon dark matter with mass 1.9$\,\mathrm{eV}/c^2$.