β decay of the very neutron-deficient Ge 60 and Ge 62 nuclei

Abstract

We report here the results of a study of the β decay of the proton-rich Ge isotopes, Ge60 and Ge62, produced in an experiment at the RIKEN Nishina Center. We have improved our knowledge of the half-lives of Ge62 [73.5(1) ms] and Ge60 [25.0(3) ms] and its daughter nucleus, Ga60 [69.4(2) ms]. We measured individual β-delayed proton and γ emissions and their related branching ratios. Decay schemes and absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. A total β-delayed proton-emission branching ratio of 67(3)% has been obtained for Ge60. New information has been obtained on the energy levels populated in Ga60 and on the 1/2- excited state in the βp daughter Zn59. We extracted a ground state-to-ground state feeding of 85.3(3)% for the decay of Ge62. Eight new γ lines have been added to the deexcitation of levels populated in the Ga62 daughter.