Multiple Coulomb excitation of 202Hg and 204Hg

Multiple Coulomb excitation measurements on sup(202,204)Hg have been performed with 5 MeV/u 208Pb projectiles. The ground bands are excited up to the newly discovered 6+ states and B(E2) values are derived for the 4+->2+ and 6+->4+ transitions. Whereas the 2+ and 4+ levels in the Hg isotopes with 196<=A<=204 have an almost constant energy, the 6+ levels increase in 202Hg and 204Hg, compared to the lighter isotopes, by approximately 100 and 300 keV, respectively. The relative B(E2) values in both nuclei show that the collectivity in the neutron rich Hg nuclei is of more complex origin than expected from the few proton and neutron holes with respect to the 82 and 126 major shells. (orig.)