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.