alpha decay of the longest-lived Cm isotope: 247

The alpha decay of 247Cm was studied fifty years ago using a 1.6 Bq source containing 99.4% 247Cm, and levels in 243Pu 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 243Pu. The 564.5-keV level has been tentatively assigned to the 7/2-[743] Nilsson state.