The new results of CUORE (Cryogenic Underground Observatory for Rare Events) experiment, which is investigating the nature of neutrino, have been published on Nature.

The experiment is hosted at the Gran Sasso National Laboratory (LNGS) of INFN (National Institute for Nuclear Physics) and it is designed to detect the nuclear process called ‘double beta decay process without neutrino emission’. This decay, if observed, would demonstrate for the first time that neutrinos are really Majorana fermions. The latest published results of CUORE represent the largest data set ever acquired by a solid-state detector-based experiment and attest that CUORE is one of the most sensitive experiments for the study of this very rare nuclear process.

Researchers at IMM Bologna, in collaboration with the group of INFN Bologna who has been working on CUORE, are involved in one of the related successor experiments of CUORE, that is to say CUPID (CUORE Upgrade with Particle Identification).

To identify and distinguish beta decays with much higher accuracy, CUPID aims at combining the bolometric technique used in CUORE experiment with the simultaneous detection of emitted light in a detector working under extreme radiopurity conditions. The figure shows a sketch of a CUPID scintillating bolometer: a specific crystal is cooled down to few mils degree Kelvin, so that a minimal release of energy in its interior (as for example in the beta decay we are looking for) can determine both an increase of temperature and a minimum production of light. In case a light signal is measured at the exit from the crystal, the result will give insight into the nature of the particle that interacted with the crystal.

The activity of researchers at IMM Bologna involved with CUPID is exactly focused on the study and development of the cryogenic bolometers.