Geochemical evidence of the double β decay of 100Mo -: art. no. 025501

Enrichment of the Ru-100 isotope, resulting from the double beta (betabeta) decay of Mo-100, has been found in old molybdenites from Australia. Using Re-Os ages determined here together with the amount of excess Ru-100 determined via isotope dilution mass spectrometry, consistent half-lives were obtained from two different molybdenite samples of varying ages (2.90 billion and 1.05 billion years old) with an average half-life of (2.1+/-0.3)x10(18) years. This half-life is highly consistent with the theoretical model for a two-neutrino betabeta decay.