B(E2)up arrow measurements for radioactive neutron-rich Ge isotopes: Reaching the N=50 closed shell

Abstract

The B(E2;0(1)(+)-> 2(1)(+)) values for the radioactive neutron-rich germanium isotopes Ge-78,Ge-80 and the closed neutron shell nucleus Ge-82 were measured at the HRIBF using Coulomb excitation in inverse kinematics. These data allow a study of the systematic trend between the subshell closures at N=40 and 50. The B(E2) behavior approaching N=50 is similar to the trend observed for heavier isotopic chains. A comparison of the experimental results with a shell model calculation demonstrates persistence of the N=50 shell gap and a strong sensitivity of the B(E2) values to the effective interaction.