The double beta decay of 116Cd has been investigated with the help of radiopure enriched 116CdWO4 crystal scintillators (1.162 kg) at the Gran Sasso underground laboratory. The half-life of 116Cd relative to the two neutrino double beta decay to the ground state of 116Sn was measured with the highest up-to-date accuracy as T1/2=(2.63±0.11)´1019 yr. A new improved limit on the neutrinoless double beta decay of 116Cd to the ground state of 116Sn was set as T1/2 > 2.2´1023 yr at 90% C.L., which is the most stringent known restriction for this isotope (corresponds to the effective Majorana neutrino mass limit in the range of 1.0 - 1.7 eV, depending on the nuclear matrix elements used in the estimations). New improved half-life limits for double beta decay with majoron(s) emission, Lorentz-violating decay, and transitions to excited states of 116Sn were set at the level of > 1020 – 1022 yr. New limits for the hypothetical lepton-number violating parameters (right-handed current admixtures in weak interaction, the effective majoron-neutrino coupling constants, R-parity violating parameter, Lorentz-violating parameter, heavy neutrino mass) were set.
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Volodymyr Tretyak
Institute for Nuclear Research
Kyiv, Ukraine