Optical-model analysis of the elastic scattering of 100 MeV protons from 24Mg and 28Si

Abstract

Elastic scattering differential cross sections for the interaction of 100 MeV protons with 24Mg and 28Si have been measured using a high-resolution Ge(Li) spectrometer to resolve the inelastic scattering contribution to the elastic peak. The results have been analysed using the conventional optical model, and the experimental differential cross sections and total reaction cross section are excellently reproduced. The results agree with previous analyses of the elastic scattering of 100 MeV protons on 1p shell nuclei in that no set of geometric parameters can provide a quantitative fit to both nuclei. It is observed, however, that the fluctuations of the optical-model parameters for optimum fits are decreased over the fluctuations observed for the 1p shell nuclei. The present results combined with previous optical-model analyses on 24Mg and 28Si at 50 MeV and 40 MeV respectively, are found to be consistent with an energy dependence of d V/d E ≈ −0.3 for the depth of the real central potential in agreement with other, more extensive, investigations of the energy dependence for protons elastically scattered from 16O and 40Ca.