High spin states are observed for the first time in the neutron-rich nuclei ${}^{151,153}\mathrm{Pr}$, ${}^{157}\mathrm{Sm}$, and ${}^{93}\mathrm{Kr}$ from the spontaneous fission of ${}^{252}\mathrm{Cf}$. Twenty new transitions in ${}^{151}\mathrm{Pr}$, twelve in ${}^{153}\mathrm{Pr}$, five in ${}^{157}\mathrm{Sm}$, and four in ${}^{93}\mathrm{Kr}$ were identified by using x-ray(Pr/Sm)-$\gamma$-$\gamma$ and $\gamma$-$\gamma$-$\gamma$ triple coincidences. From the measured total internal conversion coefficients ${\alpha }_T$ of four low-energy transitions in ${}^{151,153}\mathrm{Pr}$, we determine that two bands in each nucleus have opposite parity. The interlacing $E1$ transitions between the bands suggest a form of parity doubling in ${}^{151,153}\mathrm{Pr}$. New bands in ${}^{157}\mathrm{Sm}$ and ${}^{93}\mathrm{Kr}$ are reported. The half-life of the 354.8 keV state in ${}^{93}\mathrm{Kr}$ is measured to be 10(2) ns.

• Received 7 June 2010

DOI:https://doi.org/10.1103/PhysRevC.82.034308