Number 96 (Story #1), September 29, 1992 by Phillip F. Schewe and Ben Stein FIRST OBSERVATION OF BOUND-STATE BETA DECAY . The beta decay of a nucleus in which the emitted electron becomes bound in the daughter atom was first predicted in 1947. Now scientists at the Institute of Heavy Ion Research (GSI) at Darmstadt, Germany have observed such a decay in completely ionized (+66) dysprosium atoms circulating in a storage ring. Although neutral Dy is stable, in a fully stripped form it decays via bound-state beta decay into highly ionized (+66) holmium (atomic number 67) with a halflife of 47 (+5,-4) days, a value derived from the measured storage time of the holmium daughter ions. The GSI scientists report that bound-state beta decay is of minor importance for neutral atoms but might be the predominant decay mode for highly ionized atoms, such as those inside stellar plasmas during nucleosynthesis. Studies of these decays (which are accompanied by a essentially monoenergetic antineutrino) may lead to more precise bounds on the mass of the antineutrino. (M. Jung et al., Phys. Rev. Lett., 12 Oct. 1992.)