New Radioactive Nuclides of the Rare Earths

Abstract

Proton bombardment of pure ${\mathrm{Er}}_2$ ${\mathrm{O}}_3$, followed by ion-exchange separation, has yielded an unreported radionuclide of erbium with a 3.6-hour half-life. It is assigned to ${\mathrm{Er}}^{161}$ and decays by $K$ capture with gamma rays of 0.195, 0.824, and 1.12-Mev energy. Its daughter, 2.5-hour ${\mathrm{Ho}}^{161}$, was also identified and was observed to decay by $K$ capture with a 0.090-Mev gamma ray.