Angular Correlation Measurements in the Decay ofCd115m

Abstract

Levels in ${\mathrm{In}}^{115}$ at 650, 930, 1125, 1285, 1420, and 1540 keV are populated in the decay of ${\mathrm{Cd}}^{115m}$ (43 days). The experimentally determined coefficients of the gamma-gamma angular correlation function for the cascades 485-930 and 160-1125 keV are $A_2=-0.023\mathrm{}\pm 0.005$, $A_4=0.013\mathrm{}\pm 0.012$; $A_2=-0.107\mathrm{}\pm 0.011$, $A_4=0.021\mathrm{}\pm 0.017$, respectively. The coefficient of the $\beta -\gamma$ directional correlation function between the unique first forbidden beta transition and the following 930-keV gamma ray is found as $A_2=0.0088\mathrm{}\pm 0.0076$. Spin assignemnts for the excited state in ${\mathrm{In}}^{115}$, which are consistent with the experimental results, are $\frac{7}{2}$ (930 keV), $\frac{11}{2}$ (1125 keV), $\frac{9}{2}$ (1280 keV) and $\frac{9}{2}$ (1420 keV). The quadrupole-dipole mixing has been determined for the cascading gamma rays. From delayed-coincidence measurements, the half-lives of 930- and 1420-keV levels were found to be shorter than 3×${10}^{-10\mathrm{}}$ sec and 1.1×${10}^{-9\mathrm{}}$ sec, respectively.