The level structures of ${}^{212}\mathrm{Ra}$ and ${}^{213}\mathrm{Ra}$ have been established via time-correlated $\gamma$-ray spectroscopy following the ${}^{204}\mathrm{Pb}$(${}^{12}\mathrm{C},4n$)${}^{212}\mathrm{Ra}$ and ${}^{204}\mathrm{Pb}$(${}^{13}\mathrm{C},4n$)${}^{213}\mathrm{Ra}$ reactions. In ${}^{212}\mathrm{Ra}$, levels up to $\sim 6.2\mathrm{MeV}$ were identified and firm spin-parity assignments were achieved to a $J^{\pi }={19}^{+}$ isomer with a mean life of 31(3) ns. For ${}^{213}\mathrm{Ra}$ the corresponding values were $\sim 4.5\mathrm{MeV}$ in excitation energy and $J^{\pi }=33/2^{+}$. Two isomeric states with $J^{\pi }=23/2^{+}, \tau =27\left(3\right)$ ns and $J^{\pi }=33/2^{+}, \tau =50\left(3\right)$ ns were discovered in ${}^{213}\mathrm{Ra}$. The experimental data were compared with semiempirical shell-model calculations, which allowed dominant configurations to be assigned to most of the observed levels.

• Received 7 October 2017
• Revised 4 December 2017

DOI:https://doi.org/10.1103/PhysRevC.97.014323