Mass spectrometric analyses show the presence of curium-246 and curium-247 in curium samples produced from neutron-irradiated plutonium. The pile-neutron capture cross sections of ${\mathrm{Am}}^{243}$, ${\mathrm{Cm}}^{244}$, ${\mathrm{Cm}}^{245}$, ${\mathrm{Cm}}^{246}$ are 115±20, 25±10, 200±100, and 15±10 barns, respectively. The alpha-disintegration half-life of ${\mathrm{Cm}}^{244}$ is calculated to be 19.2±0.6 years.

• Received 15 February 1954

DOI:https://doi.org/10.1103/PhysRev.94.974