Dark matter haloscope with a disordered dielectric absorber

Light dark matter candidates such as axions and dark photons generically couple to electromagnetism, yielding dark-matter-to-photon conversion as a key search strategy. In addition to resonant conversion in cavities and circuits, light dark matter bosons efficiently convert to photons on material interfaces, with a broadband power proportional to the total area of these interfaces. In this work, we make use of interface conversion to develop a new experimental dark matter detector design: the disordered dielectric detector. We show that a volume filled with dielectric powder is an efficient, robust, and broadband target for axion-to-photon or dark-photon-to-photon conversion. We perform semi-analytical and numerical studies in small-volume 2D and 3D disordered systems to compute the conversion power as a function of dark matter mass. We also discuss the power gathered onto a sensitive photodetector in terms of the bulk properties of the disordered material, making it possible to characterize the predicted dark-matter-to-photon conversion rate across a wide range of wavelengths. Finally, we propose DPHaSE: the Dielectric Powder Haloscope SNSPD Experiment which is composed of a disordered dielectric target, a veto system, and a photon collection chamber to maximize the coupling between the powder target and a low noise superconducting nanowire single photon detector (SNSPD). With ambitious but realistic improvements to sensor area and detection efficiency at low energy, the projected reach in the 10 meV-eV mass range is sensitive to QCD axion-photon couplings and exceeds current constraints on dark photon dark matter by up to 5 orders of magnitude.