Properties of Gamma Transitions in the Decays ofSm153andGd153intoEu153

Abstract

The energies and relative intensities of gamma rays produced in the electron-capture decay ${\mathrm{Gd}}^{153}$\ensuremath{\rightarrow}${\mathrm{Eu}}^{153}$ and of the low-energy gamma rays produced in the beta decay ${\mathrm{Sm}}^{153}$\ensuremath{\rightarrow}${\mathrm{Eu}}^{153}$ have been studied with the bent-crystal spectrometer. Two previously unreported gamma rays have been observed at 54.19 and 68.23 keV. These together with a previously reported 151.5-keV gamma transition depopulate a new state at 151.61 keV which we propose as the ${\frac{7}{2}}^{\ensuremath{-}}$, $K=\frac{5}{2}$ level of ${\mathrm{Eu}}^{153}$. The $M1$ gamma-ray interband branching ratio from the known 173-keV ${\frac{5}{2}}^{+}$, $K=\frac{3}{2}$ level and the $E1$ gamma branching ratio from the 151.61-keV level are examined for evidence of band mixing.