The (α, 6He) reaction and other two-neutron transfer reactions leading to 24Mg and 152Sm

Abstract

We have analysed the only three (α, 6He) experiments we have been able to find in the literature, two on 26Mg and one on 154Sm. In the 26Mg case, we have further looked at alternative two-neutron transfer reactions, such as (p, t) and ( 16O, 18O), by using a deformed nuclear model and including direct and multistep inelastic processes in the reaction description for both ground and gamma bands. For the ground-state transition, and for some other specific cases, we have also taken into account the sequential two one-neutron transfer mechanism. We conclude that the sequential processes play an important role for the ground-state transition of the Mg reaction, and they have angular distributions substantially different from those of the corresponding direct transitions. We further provide a reasonably consistent picture of the population of the unnatural parity 3 + state in the gamma band, which is not affected by the direct transfer process, but can be reached mainly by multistep inelastic processes and in a modest way by the sequential process.