“…However, this process still remains unobserved, and only half-life limits for 0ν2β mode were obtained (see, e.g., reviews [1]) 1 One of the most sensitive 2β experiments has been performed in the Solotvina Underground Laboratory [7] by the Kiev-Firenze collaboration with the help of enriched cadmium tungstate ( 116 CdWO 4 ) crystal scintillators [8,9]. The half-life limit on 0ν2β decay of 116 Cd was set as T 1/2 ≥ 1.7 × 10 23 yr at 90% C.L., which corresponds to an upper bound on the effective Majorana neutrino mass m ν ≤ 1.7 eV [9]. This result is among the strongest world-wide restrictions on m ν (in addition to the bounds obtained in experiments with 76 Ge, 82 Se, 100 Mo, 130 Te, and 136 Xe).…”