Spontaneous-Fission Decay Constant ofAm241

The ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ spontaneous-fission decay constant has been determined with solid-state track recorders of preetched mica. Measurements have been carried out with electroplated ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ sources. Consistent spontaneousfission-rate measurements have been obtained for a large range of fission track densities over more than a 3-yr period. Systematic error due to source impurities has been established as insignificant relative to statistical error. The present experimental result for the ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ spontaneous-fission decay constant is ${\lambda }_f=(6.04\mathrm{}\pm 0.13)\times {10}^{-15\mathrm{}}$ ${\mathrm{yr}}^{-1\mathrm{}}$.