Quadrupole and octupole shapes in nuclei

Abstract

Heavy-ion coulomb excitation measurements can determine almost the complete set of ⩾ 100 E2 matrix elements involving the lowest ⩽30 collective states in nuclei, as well as E3 matrix elements. The completeness of the E2 data is sufficient to determine directly the centroids and fluctuation widths of the E2 properties in the principal axis frame, providing a direct measure of the correlation of the E2 data for low-lying states. This adds a powerful new dimension to the study of quadrupole collectivity in nuclei. The E3 matrix elements provide a sensitive test of octupole deformation in nuclei. The results and model implications of recent coulomb excitation measurements of the quadrupole shapes in odd-and even-A nuclei will be discussed, including examples of shape transitions, shape coexistence, and coriolis effects. The results of a study of octupole deformation in 148Nd also will be presented.