Superconducting Microresonator Detectors for Neutrino Physics in Milano

Superconducting microwave microresonators are low temperature detectors compatible with large-scale multiplexed frequency domain readout. Our aim is to adapt and further advance the technology of microresonator detectors to develop new devices applied to the problem of measuring the neutrino mass. More specifically, we aim to develop detector arrays which can be applied to the calorimetric measurement of the energy spectra of ¹⁶³Ho EC decay (Q ~ 2-3 keV) for a direct measurement of the neutrino mass. In order to achieve this goal, a study aimed to the selection of the best design and material for the detectors is required. A recent advance in microwave microresonator technology was the discovery that some metal nitrides, such as TiN, possess properties consistent with very high detector sensitivity. In this contribution, our progress on the design and test of Ti/TiN multilayer films is presented. We report measurements made on stoichiometric TiN, sub-stoichiometric TiN and multilayer Ti/TiN films including the critical temperature, the gap parameter and the quasi-particle recombination time extrapolated from ~keV X-ray pulses.