High sensitivity 2 beta decay study of 116Cd and 100Mo with the BOREXINO counting test facility (CAMEO project)

The unique features (super-low background and large sensitive volume) of the CTF and BOREXINO set ups are used in the CAMEO project for a high sensitivity study of 100Mo and 116Cd neutrinoless 2 beta decay. Pilot measurements with 116Cd and Monte Carlo simulations show that the sensitivity of the CAMEO experiment (in terms of the half-life limit for 0ν2β decay) is ≈4×1024 yr with a 1 kg source of 100Mo and ≈1026 yr with ≈100 kg of enriched 116CdWO4 crystals placed in the liquid scintillator of the CTF. The last value corresponds to a limit on the neutrino mass of mν ≤ 0.06 eV. Similarly with 1000 kg of 116CdWO4 crystals located in the BOREXINO apparatus the neutrino mass limit can be pushed down to mν ≤ 0.02 eV.