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A new step of the [sup 116]Cd 2β-decay experiment is in progress at the Solotvina Underground Laboratory. The upgraded setup consists of four enriched [sup 116]CdWO[sub 4] crystal scintillators of total mass 339 g. As an active shield, 15 CdWO[sub 4] crystals (20.6 kg) are used. The background rate (in the energy interval 2.7-2.9 MeV) is 0.06 count/(yr kg keV), one order of magnitude lower than in the previous apparatus. Combined with results of preceding measurements, the half-life limit for the neutrinoless 2β decay of [sup 116]Cd to the ground state of [sup 116]Sn is determined as T[sub ½](0v) ≥ 5.1 x 10[sup 22] yr with 90% C.L. The limits on T[sub ½] for transitions to the excited 2[sup +, sub 1] and 0[sup +, sub 1] levels of [sup 116]Sn are 8.6 x 10[sup 21] and 4.1 x 10[sup 21] yr, respectively (at a 90% C.L.). For 0v2β decay accompanied by the emission of one and two Majorons, the constraints on the half-life are T[sub ½](0vM1) ≥ 1.4 x 10[sup 21] yr and T[sub ½] (0vM2) ≥ 4.1 x 10[sup 20] yr (at a 90% C.L.). The corresponding constraints on the neutrino mass and the neutrino-Majoron coupling constant are 〈m[sub v]〉 ≤ 3.1 eV and 〈g[sub M]〉 ≤ 1.9 x 10[sup -4], respectively. [ABSTRACT FROM AUTHOR]

Studies of the 2β decay of 116Cd, 180W and 186W have been performed in the Solotvina Underground Laboratory with the help of the super-low background 116CdWO4 crystal scintillators. The half-life value of the two-neutrino 2β decay of 116Cd has been revised as T1/22ν=2.9±0.1(stat)−0.3+0.4(syst)×1019 yr. Besides, the new half-live limits on different modes of this process have been established for two natural tungsten isotopes, in particular, T1/2≥1.0 (1.6)×1021 yr at 90% (68%) C.L. for the neutrinoless 2β decay of 186W to the ground (0+) and first excited (2+) level of 186Os. [Copyright &y& Elsevier]