Two-neutrino 2 β decay of 116Cd and new half-life limits on 2 β decay of 180W and 186W

Abstract

Studies of the 2 β decay of 116Cd, 180W and 186W have been performed in the Solotvina Underground Laboratory with the help of the super-low background 116CdWO 4 crystal scintillators. The half-life value of the two-neutrino 2 β decay of 116Cd has been revised as T 1/2 2ν=2.9±0.1( stat) −0.3 +0.4( syst)×10 19 yr. Besides, the new half-live limits on different modes of this process have been established for two natural tungsten isotopes, in particular, T 1/2⩾1.0 (1.6)×10 21 yr at 90% (68%) C.L. for the neutrinoless 2 β decay of 186W to the ground (0 +) and first excited (2 +) level of 186Os.