Mass and low-lying levels ofGe67; trends in the structure ofNi63,65,Zn65,67, andGe67,69

Abstract

${}_{32}{}^{67}{}_{}{}^{}\mathrm{Ge}_{35}^{}{}_{}{}^{}$ has been studied via the reaction ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}(\alpha ,n\gamma ){}_{}{}^{67}{}_{}{}^{}\mathrm{Ge}$. The mass excess was measured to be -62666 ± 12 keV, and four low-lying excited states have been identified. Among these newly identified levels is an isomeric state at 18.2 keV having a measured total mean lifetime of 18.5 ± 0.3 μs and a measured $K$-shell internal conversion coefficient ${\alpha }_K=176\mathrm{}\pm 29$. In addition, the total lifetime of the 63.4 keV isomeric level in ${}_{}{}^{65}{}_{}{}^{}\mathrm{Ni}$ has been measured to be 104.9 ± 7.1 μs. The level schemes of the six nuclei ${}_{}{}^{63,65}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{65,67}{}_{}{}^{}\mathrm{Zn}$, and ${}_{}{}^{67,69}{}_{}{}^{}\mathrm{Ge}$ are then compared, and similarities in their structure and in the decay characteristics of the isomeric states of each are discussed and interpreted in terms of a simple pairing model.