Abstract
We present the optical model analysis of proton elastic scattering on light nuclei, with improved spin-orbit force, in the energy range 50 to 160 MeV. The particular potentials are determined by varying independently all the parameters of the phenomenological optical potential for p + 12C elastic scattering and good description is obtained for this target nucleus in the energy range considered. Then, the average potential is deduced. When this average potential is used, without parameter adjustment, to describe p +16O elastic scattering a comparable fit to the data is obtained. The dependence on mass number comes only through the half-way radius. Furthermore, when this potential is applied to other neighbouring nuclei, ranging from 9Be to 14N, similar acceptable fits to the above data are also obtained. Hence, the validity of our average potential is not restricted to the target nuclei having only alpha-cluster structure. The spin-orbit potential is calculated microscopically using the impulse approximation and the first-order multiple scattering theory. This potential is then given finer adjustments to optimize the fit to the polarisation data. This results in the spin-orbit potential having different parameters for their real and imaginary parts. The six-parameter model is more in accord with the microscopic findings and it gives improved description to the experimental data.