Inverse-kinematics proton scattering on 50 Ca: determining effective charges using complementary probes

A comparison of the present results with those from previous measurements of the lifetimes of the 2 + states provides us the ratio of the neutron and proton matrix elements for the 0 +.s. ! 2 + transitions. These results allow the determination of the ratio of the proton and neutron effective charges to be used in shell model calculations of neutron-rich isotopes in the vicinity of 48 Ca. Isotopes within a few nucleons of the doubly-magic nuclei provide the foundation for the nuclear shell model. The simplicity of the wavefunctions of the valence nucleons in these nuclei allows the determination of the two-body matrix elements necessary for predicting the energies of excited states and the effective charges used in calculating transition strengths in a given shell-model space. Effective charges reflect the strength of the coupling between the motion of the valence nucleons and the virtual excitations of the core nucleons.