High spin states inPr151,153,Sm157, andKr93

Abstract

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)-$\ensuremath{\gamma}$-$\ensuremath{\gamma}$ and $\ensuremath{\gamma}$-$\ensuremath{\gamma}$-$\ensuremath{\gamma}$ triple coincidences. From the measured total internal conversion coefficients ${\ensuremath{\alpha}}_{T}$ 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.