Inverse-kinematics proton scattering from S,4442, P,4341, and the collapse of the N =28 major shell closure
Excited states of the neutron-rich isotopes S,4442 and P,4341 have been studied via inverse-kinematics proton scattering from a liquid hydrogen target, using the GRETINA γ -ray tracking array to extract inelastic-scattering cross sections. Deformation lengths of the 21+ excitations in S,4442 have been determined and, when combined with deformation lengths determined with electromagnetic probes, yield the ratio of neutron-to-proton matrix elements Mn/Mp for the 21+ excitations in these nuclei. The present results for P,4341(p ,p') are used to compare two shell-model interactions, SDPF-U and SDPF-MU. As in a recent study of 42Si, the present results on P,4341 favor the SDPF-MU interaction.