α decay of the longest-lived Cm isotope: Cm96247

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, $\ensuremath{\gamma}$-ray spectra were measured with a more efficient Ge detector. A $\ensuremath{\gamma}$-ray spectrum was also measured in coincidence with $\ensuremath{\alpha}$ particles for a period of two months and has 80 times more counts than the previously published spectrum. $\ensuremath{\gamma}$-ray energies were determined with higher precision and four new $\ensuremath{\gamma}$ rays were identified. A new high-energy $\ensuremath{\gamma}$ 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 $7/{2}^{\ensuremath{-}}[743]$ Nilsson state.