NEUTRINOLESS DOUBLE BETA DECAY: CURRENT STATUS AND PERSPECTIVES. THE CAMEO PROJECT

Abstract

0ν2β decay is a very powerful tool for probing the physics beyond the particle Standard Model. After the recent discovery of neutrino flavor oscillation, we know that neutrinos must have a mass (at least two of them). The 0ν2β decay discovery could fix the neutrino mass scale and its nature (Majorana particle). The unique characteristics of the Borexino detector and its Counting Test Facility (CTF) can be employed for high sensitivity studies of 116 Cd 0ν2β decay: the CAMEO project. A first step foresees 24 enriched 116 CdWO 4 crystals for a total mass of 65 kg in the Counting Test Facility; then, 370 enriched 116 CdWO 4 crystals, for a total mass of 1 ton in the Borexino detector. Measurements of 116 CdWO 4 crystals and Monte Carlo simulations have shown that the CAMEO experiment sensitivity will be [Formula: see text], for the 65 kg phase, and [Formula: see text] for the 1 ton phase; consequently the limit on the effective neutrino mass will be ≤ 60 meV, and ≤ 20 meV, respectively. This work is based upon the experiments performed by the INR (Kiev) (and from 1998 also by the University of Florence) at the Solotvina Underground Laboratory (Ukraine). The current status of 0ν2β, and future projects of 0ν2β decay research are also briefly reviewed.