Kinetic inductance detectors on calcium fluoride substrate for astroparticle physics

We propose the utilization of inorganic crystals as substrates for kinetic inductance detectors (KIDs), which are thin-film superconducting resonators, for future rare event studies. When energy is deposited on the substrate, phonons are generated and propagate from the substrate to the surface, where KIDs are fabricated. This approach expands the potential for utilizing a diverse range of target crystals. We implement KIDs on calcium fluoride (CaF2) substrates, since 19F is sensitive to dark matter with spin-dependent interaction and 48Ca is one of the double-beta decay nuclei. We have experimentally demonstrated the operation of the KIDs on the CaF2 substrate and their phonon-mediated particle detection.