Characterizing the atomic mass surface beyond the proton drip line via alpha-decay measurements of the pi s(1/2) ground state of Re-165 and the pi h(11/2) isomer in Ta-161

Abstract

The alpha-decay chains originating from the pi s(1/2) and pi h(11/2) states in Au-173 have been investigated following fusion-evaporation reactions. Four generations of alpha radioactivities have been correlated with Au-173(m) leading to a measurement of the alpha decay of Ta-161(m). It has been found that the known alpha decay of Ta-161, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt gamma rays feeding the ground state of Au-173. This prompt gamma radiation was used to aid the study of the alpha-decay chain originating from the pi s(1/2) state in Au-173. Three generations of alpha decays have been correlated with this state, leading to the observation of a previously unreported activity which is assigned as the decay of Re-165(g). This work also reports the excitation energy of an alpha-decaying isomer in Ta-161 and the Q(alpha) value of the decay of Ta-161(g). DOI:10.1103/PhysRevC.86.064315