The alpha decay of ${}^{247}\mathrm{Cm}$ was studied fifty years ago using a 1.6 Bq source containing 99.4% ${}^{247}\mathrm{Cm}$, and levels in ${}^{243}\mathrm{Pu}$ were deduced. Using the same source, $\gamma$-ray spectra were measured with a more efficient Ge detector. A $\gamma$-ray spectrum was also measured in coincidence with $\alpha$ particles for a period of two months and has 80 times more counts than the previously published spectrum. $\gamma$-ray energies were determined with higher precision and four new $\gamma$ rays were identified. A new high-energy $\gamma$ ray of 564.5 keV was observed, which is interpreted as a transition between a level at 564.5 keV and the ground state of ${}^{243}\mathrm{Pu}$. The 564.5-keV level has been tentatively assigned to the $7/2^{-}\left[743\right]$ Nilsson state.

• Received 11 November 2022
• Accepted 9 December 2022

DOI:https://doi.org/10.1103/PhysRevC.106.064329