Radioactive Cerium and Praseodymium

Abstract

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