New bound to the probability of ⁷⁶Ge ββ decay to the 0

Measurements were carried out at the underground low-background laboratory of the Baksan Neutrino Observatory using a detection system involving four ultrapure germanium detectors made from enriched Ge-76. The sensitivity of the experiment to the detection of a Ge-76 double beta decay to the excited levels of the Se-76 nucleus was determined. As a result of 228-day measurements, the new bound to the time of Ge-76 half-decay to the Se-76 0(1)(+) excited level is found to be T-1/2(2 nu2 beta) greater than or equal to 6.2 x 10(21) years (90% confidence level). (C) 2000 MAIK "Nauka / Interperiodica".