High energy resolution thermal microcalorimeters for the HOLMES experiment

Abstract HOLMES is an experiment aimed at directly measuring the neutrino mass through the calorimetric measurement of the 163 Ho electron capture decay. The final goal of the project consists in providing a sensitivity on the neutrino mass below 2 eV; in addition, it will establish the potential of this approach to achieve a sub-eV sensitivity. The detectors performances play a crucial role in achieving the desired sensitivity. Indeed, for such an experiment, the following characteristics are required: short response time ( ∼ 1 μ s ) to solve pile-up events, great energy resolution ( ∼ 1 eV @ 2.8 keV) and compatibility to be multiplexed in large detector arrays ( ≳ 1000). HOLMES will deploy 1000 Transition Edge Sensors which will be readout with the microwave multiplexing technique. In this contribution we outline the experimental setup used in the characterization phase of the detectors.