Lifetime Measurements of the Neutron-Rich N=30 Isotones 50Ca and 51Sc: Orbital Dependence of Effective Charges in the fp Shell

The lifetimes of the first excited states of the N=30 isotones 50Ca and 51Sc have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f7/2 shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus 48Ca, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.