The data analysis of BULLKID. A monolithic array of particle absorbers sensed by KIDs

We present the calibration and data analysis of BULLKID, a cryogenic, low threshold particle detector for searches of low mass dark matter candidates and coherent neutrino on nucleus scattering (CE휈NS) events. The BULLKID detector is an array of 60 cubic particle absorbers made out of 0.34 g of silicon per cube, each one sensed by a kinetic inductance detector (KID). This paper describes the energy calibration of the detector as well as an evaluation of the background rate of the device when operated in an above-ground unshielded environment. By performing coincidence cuts on a cluster of 3x3 dice, the background rejection power of the design is demonstrated, allowing reach to a flat background down to a threshold of 160 eV.