We demonstrate position and energy-resolved phonon-mediated detection of particle interactions in a silicon substrate instrumented with an array of microwave kinetic inductance detectors ( MKIDs ) .
The relative magnitude and delay of the signal received in each sensor allows the location of the interaction to be determined with \lesssim 1 mm resolution at 30 keV .
Using this position information , variations in the detector response with position can be removed , and an energy resolution of \sigma _ { E } = 0.55 keV at 30 keV was measured .
Since MKIDs can be fabricated from a single deposited film and are naturally multiplexed in the frequency domain , this technology can be extended to provide highly-pixelized athermal phonon sensors for \sim 1 kg scale detector elements .
Such high-resolution , massive particle detectors would be applicable to rare-event searches such as the direct detection of dark matter , neutrinoless double-beta decay , or coherent neutrino-nucleus scattering .