Identifying Drivers of Energy Resolution Variation in a Multi-KID Phonon-Mediated Detector

Phonon-mediated Kinetic Inductance Detectors (KIDs) on silicon substrates have demonstrated both 𝒪 (10) eV energy resolution and mm position resolution when used as particle detectors, making them strong candidates for instrumenting next-generation rare event experiments such as in looking for dark matter. Previous work has demonstrated the performance of an 80-KID array on a Si wafer; however, current energy resolution measurements show a ∼ 25 × difference between otherwise identical KIDs—between 5 and 125 eV on energy absorbed by the KID. Here, we use a first principles approach and attempt to identify the drivers behind the variation. In particular, we analyze a subset of 8 KIDs using the unique approach of pulsing neighboring KIDs to generate signals in the target. We tentatively identify differences in quality factor as the likely culprit for the observed differences.