Assess the neutrino mass with micro and macro calorimeter approach

Abstract

Abstract. Thanks to oscillation experiments it is now an established fact that neutrinos are massive particles. Yet, the assessment of neutrinos absolute mass scale is still an outstanding challenge in particle physics and cosmology as oscillation experiments are sensitive only to the squared mass differences of the three neutrino mass eigenstates. The mass hierarchy is not the only missing piece in the puzzle. Theories of neutrino mass generation call into play Majorana neutrinos and there are experimental observations pointing toward the existence of sterile neutrinos in addition to the three weakly interacting ones. Three experimental approaches are currently pursued: an indirect neutrino mass determination via cosmological observables, the search for neutrinoless double β-decay, and a direct measurement based on the kinematics of single β or electron capture decays.Bolometers and calorimeters are low temperature detectors used in many applications, such as astrophysics, fast spectroscopy and particle physics. In particular, sensitive calorimeters play an important role in the neutrino mass measurement and in the search for the neutrinoless double β-decay. There has been great technical progress on low temperature detectors since they were proposed for neutrino physics experiments in 1984. This general detector paradigm can be implemented in devices as small as a micrometer for sub eV radiation or as large as 1 kg for MeV scale particles. Today this technique offers the high energy resolution and scalability required for leading edges and competitive experiments addressing the still open questions in neutrino physics.

Working principle and demonstrator of microwave-multiplexing for the HOLMES experiment microcalorimeters

“…The pulse response must be fast enough to match the rate of the source while a rapid pulse rise can facilitate the pile-up rejection. In a low temperature calorimeter the decay time (τ f ) is set by the ratio between the thermal capacity C of the absorber and the thermal conductance G toward the bath [62,63]. The rise time, at the first order, is set by the electrical cutoff of L N /R 0 , where R 0 is the resistance of the sensor at the working point, and L N is a selectable Nyquist inductance connected in series to the TES.…”