Interacting boson approximation model analysis ofE2transition probabilities for transitions inEr166−170

The experimental results from Coulomb excitation of vibrational-like $2^{+}$ states in ${}_{}{}^{166-170}{}_{}{}^{}\mathrm{Er}$ are compared with the predictions of the interacting boson approximation model. The breaking of the SU(3) symmetry by the pairing term plays a crucial role in giving a much better account of the $B\left(E2\right)$ values for decay of the $K$,$J^{\pi }=0,2^{+}$ state. In general, the interacting boson approximation model provides a detailed quantitative description of the level energies and of the $E2$ transition probabilities.