The lifetimes of the first excited states of the N = 30 isotones (50)Ca and (51)Sc 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 f_{7/2} shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus (48)Ca, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.

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Excited states in 30 Mg have been populated to ∼6h and 5 MeV excitation energy with the 14 C( 18 O,2p) reaction. Firm spin assignments for states with J > 2h have been made in this nucleus. The level scheme is compared to shell-model calculations using the Universal sd effective interaction and the Monte Carlo shell model method. Calculations employing a full sd model space fail to reproduce the observed levels. The results indicate that excitations across the N = 20 gap are required at relatively low excitation energy to achieve a description of the data. The incorporation of the f 7/2 and p 3/2 orbitals into the model space gives improved results but indicate the need for further refinement of the models to reproduce the observed spectra.

Lifetimes of low-lying excited states of the neutron-rich 44,46 Ar nuclei, populated via multinucleon transfer reactions, are measured by means of the differential recoil distance Doppler shift method. The extracted electromagnetic transition probabilities are compared with previous intermediate-energy Coulomb-excitation measurements and with large-scale shell-model calculations. The increase in the deduced B(E2; 2 + → 0 +) transition probability from 44 Ar to the closed-shell nucleus 46 Ar contradicts the earlier results of Coulomb-excitation experiments. Shell-model calculations using different effective interactions agree with the new measured values.

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