Spin-dependent effects in proton inelastic scattering

Abstract

Proton inelastic collisions leading to the excitation of surface modes in even target nuclei are considered. An extension of the phenomenological optical model is made in which both the spin-independent and spin-dependent potentials contain terms linear in the nuclear collective surface coordinates. The spin-dependent part has the full Thomas form. The T-matrix element is derived in the DWBA approximation, and expressions for inelastic observables such as cross section, polarization, asymmetry and spin flip probability are given. The theory is applied to the analysis of the inelastic scattering of protons in the energy range 29–50 MeV by several nuclei. Special attention is paid to the deformed spin-dependent interaction, where we compare the full Thomas form with a previously proposed simplified form. It is found that the use of the full Thomas form substantially improves the fit to the observed asymmetries, especially at forward scattering angles. Moreover, certain features of the measured spin-flip probabilities are reproduced only when the deformed spin-dependent interaction is of the full Thomas form.