Coulomb excitation of transitional selenium at ReA3*

⁷²Se lies in a transitional region of the nuclear landscape, between well-established prolate nuclei around ^74,76Se, and ⁷⁰Se which has been found to exhibit oblate deformation. Calculations for ⁷²Se predict a coexistence between prolate and oblate deformations, representing a transitional point in the selenium isotopic chain. The determination of the sign of deformation in ⁷²Se is thus of considerable interest in order to experimentally localize this shape transition within the selenium isotopes.

The results of a Coulomb-excitation measurement performed on ⁷²Se will be presented: the first radioactive-beam Coulomb-excitation measurement performed with the JANUS setup at the ReA3 facility at NSCL. These results demonstrate a prolate deformation in ⁷²Se, indicating a transition from prolate to oblate deformation occurs between ⁷²Se and ⁷⁰Se. Results from a ⁷⁶Se stable-beam experiment using the same setup will also be presented.