Decay ofEu157,Eu158, andEu159

The radiations of ${}_{}{}^{157}{}_{}{}^{}\mathrm{Eu}$, ${}_{}{}^{158}{}_{}{}^{}\mathrm{Eu}$, and ${}_{}{}^{159}{}_{}{}^{}\mathrm{Eu}$ were studied with $\beta$- and $\gamma$-scintillation spectroemeters and a lithium-drifted germanium detector. The energies and intensities of the major $\beta$ groups and $\gamma$ rays were determined. On the basis of $\gamma -\gamma$ coincidence measurements, the radiations of ${}_{}{}^{157}{}_{}{}^{}\mathrm{Eu}$ and ${}_{}{}^{158}{}_{}{}^{}\mathrm{Eu}$ were fitted to partial decay schemes. The total $\beta$-decay energies are 1.40±0.15 MeV for ${}_{}{}^{157}{}_{}{}^{}\mathrm{Eu}$, ${3.40}_{-0.10\mathrm{}}^{+0.20\mathrm{}}$ MeV for ${}_{}{}^{158}{}_{}{}^{}\mathrm{Eu}$, and ${2.40}_{-0.10\mathrm{}}^{+0.20\mathrm{}}$ MeV for ${}_{}{}^{159}{}_{}{}^{}\mathrm{Eu}$. The mass assignments for 15.15-h ${}_{}{}^{157}{}_{}{}^{}\mathrm{Eu}$, 45.7-min ${}_{}{}^{158}{}_{}{}^{}\mathrm{Eu}$, and 17.9-min ${}_{}{}^{159}{}_{}{}^{}\mathrm{Eu}$ were confirmed.