Radioactive Cerium and Praseodymium

Abstract

A 140\ifmmode\pm\else\textpm\fi{}1-day half-life is assigned ${\mathrm{Ce}}^{139}$. It decays by $K$-electron capture to ${\mathrm{La}}^{139}$. Two $\ensuremath{\gamma}$-rays of 0.184 and 0.8 Mev are associated with ${\mathrm{Ce}}^{139}$. The 0.184-Mev $\ensuremath{\gamma}$-ray is found to be partially internally converted, giving electrons of approximately 0.145 and 0.178 Mev. A 30.6\ifmmode\pm\else\textpm\fi{}0.7-day half-life is assigned to ${\mathrm{Ce}}^{141}$ which is found to decay by the emission of a 0.66-Mev ${\ensuremath{\beta}}^{\ensuremath{-}}$-particle and a $\ensuremath{\gamma}$-ray of approximately 0.2 Mev to stable ${\mathrm{Pr}}^{141}$. A 1.4\ifmmode\pm\else\textpm\fi{}0.1-day half-life is assigned to ${\mathrm{Ce}}^{143}$ which decays by the emission of a 1.3-Mev ${\ensuremath{\beta}}^{\ensuremath{-}}$-particle and a 0.6-Mev $\ensuremath{\gamma}$-ray to ${\mathrm{Pr}}^{143}$. A 13.5\ifmmode\pm\else\textpm\fi{}0.1 half-life is assigned ${\mathrm{Pr}}^{143}$ which decays to stable ${\mathrm{Nd}}^{143}$ by emission of a 0.83-Mev ${\ensuremath{\beta}}^{\ensuremath{-}}$-particle. The saturation intensity ratio of the ${\mathrm{Ce}}^{142}(d,n){\mathrm{Pr}}^{143}$ reaction to the ${\mathrm{Ce}}^{142}(d,2n){\mathrm{Pr}}^{142}$ reaction is found to be 2.9.