Collective modes studied by Coulomb excitation

The large gain in sensitivity provided by powerful new gamma-ray detector arrays, such as Gammasphere, coupled with other advances in the field of heavy-ion induced Coulomb excitation, open exciting new research opportunities for exploiting Coulomb excitation to probe nuclear structure. Three recent examples are given that exploit this unprecedented sensitivity. The actinide nuclei Cm-248 and Pu-240,Pu-242,Pu-244 have been Coulomb excited using Pb-208 ions at the barrier. The positive and negative-parity yrast bands have been extended to high spin, less than or equal to 34 (h) over bar, and the evolution of alignments probed. Heavy-ion induced Coulomb excitation of a Dy-162 beam is providing significant new information on states to high spin in the ground, S and gamma bands, as well as a double gamma-phonon band. Collective octupole correlations are especially strong in Pb-208 and Zr-96 implying the possible existence of localized octupole double-phonon states in these nuclei. Heavy-ion Coulomb excitation has been used to locate octupole double-phonon strength in these nuclei; the results for Pb-208 show large fragmentation of the octupole double-phonon strength whereas a major fraction of the strength may have been located for Zr-96.