Quadrupole Collectivity in Neutron-Rich Fe and Cr Isotopes

Intermediate-energy Coulomb excitation measurements are performed on the N >= 40 neutron-rich nuclei Fe-66,Fe-68 and Cr-64. The reduced transition matrix elements providing a direct measure of the quadrupole collectivity B(E2; 2(1)(+) -> 0(1)(+) are determined for the first time in Fe-68(42) and Cr-64(40) and confirm a previous recoil distance method lifetime measurement in Fe-66(40). The results are compared to state-of-the- art large-scale shell-model calculations within the full fpgd neutron orbital model space using the Lenzi-Nowacki-Poves-Sieja effective interaction and confirm the results of the calculations that show these nuclei are well deformed.