Electron Capture Decay ofAm244and the Spontaneous Fission Half-Life ofPu244

The branching ratio (electron captures/beta particles) of ${\mathrm{Am}}^{244}$ was determined as 0.039±0.003%. An enriched ${\mathrm{Pu}}^{244}$ sample was isolated from neutron irradiated ${\mathrm{Am}}^{243}$, and the spontaneous fission half-life of ${\mathrm{Pu}}^{244}$ was found to be (2.5±0.8)×${10}^{10}$ years.