Low-Energy Coulomb Excitation for the Shell Model

Abstract

Low-energy Coulomb excitation is capable of providing unique information on static electromagnetic moments of short-lived excited nuclear states, including non-yrast states. The process selectively populates low-lying collective states and is, therefore, ideally suited to study phenomena such as shape coexistence and the development of exotic deformation (triaxial or octupole shapes). Historically, these experiments were restricted to stable isotopes. However, the advent of new facilities providing intense beams of short-lived radioactive species has opened the possibility to apply this powerful technique to a much wider range of nuclei. The paper discusses the observables that can be measured in a Coulomb-excitation experiment and their relation to the nuclear structure parameters with an emphasis on the nuclear shape. Recent examples of Coulomb-excitation studies that provided outcomes relevant for the Shell Model are also presented.

Dissipative Reactions with Intermediate-Energy Beams: A Novel Approach to Populate Complex-Structure States in Rare Isotopes

“…Also, strong forward focusing enhances the collection efficiency as compared to low-energy reactions that fill a larger phase space. Multi-step Coulomb excitation studies with low-energy rare-isotope beams have been performed at beam intensities similar to those used here, but have been limited to a complementary level scheme selectively comprising cascades connected by strong E2 transitions, with at most the first 3 − state [7,26]. We illustrate this with the example of the state-of-the art low-energy Coulomb excitation of the neighboring Ca isotope 42 Ca on Pb [27].…”