Decay of 45-Day Fe59

The gamma rays following the decay of 45-day ${\mathrm{Fe}}^{59}$ have been studied using the techniques of gamma-ray scintillation spectrometry, including $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ directional correlation measurements. In addition to the previously reported 0.192-, 1.10-, and 1.29-Mev gamma rays, two additional gamma rays having energies of 0.145 and 0.337 Mev were observed. These latter two arise from a state at 1.43 Mev in ${\mathrm{Co}}^{59}$. All gamma rays were observed to decay with a half-life of 45\ifmmode\pm\else\textpm\fi{}5 days. Directional correlation measurements on the 0.14-1.29 Mev and 0.19-1.10 Mev cascades were performed. The results of these measurements, together with the gamma-ray relative intensities, suggest an assignment of \textonehalf{}- to the 1.43-Mev state in ${\mathrm{Co}}^{59}$.