New $8^{+}$ isomers in ${}^{82}\mathrm{Se}$ and ${}^{80}\mathrm{Ge}$ and their decays were studied by observing $\gamma$ rays from the projectilelike fragments produced by the deep-inelastic collision ${}^{198}\mathrm{Pt}+743\mathrm{}\hspace{0.5em}\mathrm{MeV}{}^{82}\mathrm{Se}$. The lifetimes of the $8^{+}$ isomers have been measured to be $T_{1/2}=6.6\mathrm{}\left(4\right)\mathrm{}\hspace{0.5em}\mathrm{ns}$ and $T_{1/2}>0.4\mathrm{}\hspace{0.5em}\mathrm{ns}$ ${\mathrm{for}\mathrm{}}^{82}\mathrm{Se}$ and ${}^{80}\mathrm{Ge}$, respectively. The $N=48\mathrm{}$ isotones from ${}_{32}^{80}\mathrm{Ge}$ to ${}_{46}^{94}\mathrm{Pd}$ turned out to show quite different energy spectra of the yrast states up to $I^{\pi }{=8\mathrm{}}^{+}$, depending on the orbital occupied by valence protons.

• Received 24 December 1998

DOI:https://doi.org/10.1103/PhysRevC.59.R2331