Beta Decay ofFe59

Abstract

The decay of ${\mathrm{Fe}}^{59}$ was studied with particular interest in the shape of the beta spectrum and in the comparative half-life of the very weak, highest energy beta group. This group was found to result from 0.30% of the decays and to have an end-point energy of 1.573±0.003 MeV. The experimental data could be fitted with a shape factor $p^2+3.3\mathrm{} q^2$, consistent in form with that expected for a twice-forbidden $\Delta I=2\mathrm{}$ (no) transition. The comparative half-life ($logft=10.96\mathrm{}$) is relatively short. The two more intense beta transitions are 0.475±0.003 MeV, 51.2%, $logft=6.74\mathrm{} \mathrm{and} 0.273\pm 0.005$ MeV, 48.5%, $logft=5.92\mathrm{}$. The energies of the two high-energy gamma transitions, determined from their $K$ internal conversion lines, are 1.101±0.003 and 1.300±0.003 MeV.