Speaker
Description
In this contribution we would like to present the progress of OPOSSUM. OPOSSUM aims to discriminate Single Site Events from Multi Site Events in mK calorimeters for rare-event searches. The OPOSSUM project, funded by an ERC Starting Grant in 2024, aims to improve by an order of magnitude the sensitivity of neutrinoless double-beta decay (0νββ) experiments,a key process which would redefine our understanding of neutrinos and physics beyond the Standard Model.
At the heart of OPOSSUM lies a novel discrimination strategy to positively identify 0nBB events while rejecting dominant background sources such as alpha and gamma interactions in TeO₂. Thanks to its 33% isotopic abundance, 130-Te represents a leading 0nBB candidate, avoiding the need for isotopic enrichment. In OPOSSUM, TeO2 prototype crystals will be equipped with six Microwave Kinetic Inductance Detectors (MKIDs), alongside existing thermistors. This technique has the potential to reduce the existing radioactive background below 10⁻⁴ counts/keV/kg/y, enabling sensitivity to the inverted hierarchy mass region.
We will report on the first implementation steps of superconducting films on TeO₂, Al and Ti/TiN films with resonator geometries to optimize the quality factor for particle detection. This represents a crucial milestone toward full event-topology discrimination in large-mass cryogenic detectors.