$E2\mathrm{}$ Matrix Elements Between High-Spin States in the Ground-State Bands of ${\mathrm{Sm}}^{152}$ and ${\mathrm{Sm}}^{154}$

Measurements of transition-matrix elements between states with spin up to ${10}^{+}$ in the ground-state bands of ${\mathrm{Sm}}^{152}$ and ${\mathrm{Sm}}^{154}$ indicate large deviations from the adiabatic rotational-model predictions in ${\mathrm{Sm}}^{152}$ but not in ${\mathrm{Sm}}^{154}$. The nonrotational effects are compared with band mixing deduced from $\beta$-band de-excitation matrix elements and with measurements of changes in the mean-square radius with increasing spin.