Double beta decay of 100Mo

Two-neutrino double beta decay of 100Mo with half-life T1/2=[7.2±0.9(stat)± 1.8(syst)]×1018 yr was detected using a liquid argon ionization chamber. With a C.L. of 68% (90%), the bounds on neutrinoless decay and decay with majoron emission were found to be 8.4(4.9)×1021 and 4.1(3.2)×1020 yr, respectively. An analysis of all available results provides the average “world” value T1/2=(8.0±0.7)×1018 yr for the two-neutrino decay of 100Mo, and the corresponding nuclear matrix element is MGT=0.118±0.005.