Nuclear Shapes Studied by Coulomb Excitation

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Publisher Summary This chapter discusses nuclear shapes studied by Coulomb excitation. Nuclear E2 properties are a direct and an unambiguous measure of the collective shape parameters for quadrupole collectivity. Coulomb excitation selectively excites collective states with cross sections that are a direct measure of the E2 matrix elements. Advances in the field of Coulomb excitation make it feasible to measure essentially all the E2 matrix elements for low-lying nuclear levels. The completeness and extent of this E2 information add a new dimension to the study of quadrupole collectivity in nuclei. In particular, now it is practical to use a model-independent method for extracting the collective shape parameters directly from this large body of E2 data. Coulomb excitation can now be used to address open questions such as those regarding the limits of the validity of macroscopic collective models, the role of symmetries in collective motion, and the role of shape transitions and shape coexistence in nuclear structure. It is possible to exploit the model-independent sum rule method to project the significant quadrupole collective shape degrees of freedom directly from the data. The power of the sum rule technique is that it allows a wealth of data to be transformed into a form that clearly shows the extent to which the data are correlated because of collectivity.