Differences of deformation parameterβfor different transition mechanisms; comparison with data

The differences between the isovector and isoscalar parts of the collective deformation parameter $\beta$ are obtained from the results of microscopic effective-charge theory. For single-closed-shell nuclei, differences, due to the isovector parts, of up to about 20% between ${\beta }_{n{n}^{\prime }}$ and ${\beta }_{p{p}^{\prime }}$ are predicted, ${\beta }_{n{n}^{\prime }}$ being much closer to ${\beta }_{\mathrm{em}}$ than to ${\beta }_{p{p}^{\prime }}$. Data on single-closed-shell nuclei are tabulated and their general trend supports our predictions.