Conversion-Electron Particle Parameters in the Decay ofEu152andEu154

The internal conversion-electron particle parameters of several fast low-energy $E2\mathrm{}$ transitions in the deformed nuclei ${\mathrm{Sm}}^{152}$ and ${\mathrm{Gd}}^{154}$ were determined by comparing the $e^{-}-\gamma$ directional correlations and $\gamma -\gamma$ directional correlations displayed by the same sources. Special attention was paid to eliminating the effects of scattering in the source, and the corrections caused by the presence of extranuclear perturbations of the directional correlations were carefully studied. The results are: 0.122-MeV transition in ${\mathrm{Sm}}^{152}$: $b_2(E2, K)=1.60\mathrm{}\pm 0.05$, $b_2(E2, L^{-})=1.03\mathrm{}\pm 0.05$; 0.245-MeV transition in ${\mathrm{Sm}}^{152}$: $b_2(E2, K)=1.72\mathrm{}\pm 0.07$; 0.344-MeV transition in ${\mathrm{Gd}}^{154}$: $b_2(E2, K)=1.57\mathrm{}\pm 0.13$; 0.123-MeV transition in ${\mathrm{Gd}}^{154}$: $b_2(E2, K)=1.37\mathrm{}\pm 0.07$. The two particle parameters of the 0.122-MeV ground-state transitions in ${\mathrm{Sm}}^{152}$ are about 15% lower and that of the 0.123-MeV ground state-transition in ${\mathrm{Gd}}^{154}$ is 25% lower, than the theoretical predictions for finite-size nuclei. The particle parameters of the 0.245-MeV and of the 0.344-MeV transitions agree with the theoretical values within experimental errors.