Low-energy Coulomb excitation of $^{96,98}$Sr beams

International audience; The structure of neutron-rich 96,98Sr nuclei was investigated by low-energy safe Coulomb excitation ofradioactive beams at the REX-ISOLDE facility, CERN, with the MINIBALL spectrometer. A rich set oftransitional and diagonal E2 matrix elements, including those for non-yrast structures, has been extractedfrom the differential Coulomb-excitation cross sections. The results support the scenario of a shape transition atN = 60, giving rise to the coexistence of a highly deformed prolate and a spherical configuration in 98Sr, andare compared to predictions from several theoretical calculations. The experimental data suggest a significantcontribution of the triaxal degree of freedom in the ground state of both isotopes. In addition, experimentalinformation on low-lying states in 98Rb has been obtained.