The half-life of the known $I,K^{\pi }=4^{-},4^{-}$ state in ${}^{170}\mathrm{Er}$ has been measured to be $42.8\pm 1.7\text{ns}$. The rotational band built on this isomer was excited inelastically up to spin ${18}^{-}$ by a ${}^{238}\mathrm{U}$ beam at $E_{\mathit{\text{lab}}}=1358\text{MeV}$. A similar band in ${}^{168}\mathrm{Er}$ was extended to spin ${15}^{-}$. The wave function of the isomeric state in ${}^{170}\mathrm{Er}$ has been determined from the measured $\mid g_K-g_R\mid$ values, which were deduced from the intensity ratios of the $\Delta I=1$ to $\Delta I=2$ transitions within the band. The dominant component consists of a two-quasiproton configuration involving the Nilsson orbits $7∕2^{-}\left[523\right]$ and $1∕2^{+}\left[411\right]$. In contrast, the two-quasineutron configuration involving the $7∕2^{+}\left[633\right]$ and $1∕2^{-}\left[521\right]$ Nilsson orbits constitutes the major component for the wave function of the $K^{\pi }=4^{-}$ isomer in ${}^{168}\mathrm{Er}$.

• Received 11 June 2003

DOI:https://doi.org/10.1103/PhysRevC.68.044305