Entrance Channel Phenomena in Complex Nuclear Scattering

Abstract

The elastic scattering excitation functions of the systems $^{6}\mathrm{Li}$-$^{6}\mathrm{Li}$, $^{12}\mathrm{C}$-$^{12}\mathrm{C}$, $^{14}\mathrm{N}$-$^{14}\mathrm{N}$, $^{16}\mathrm{O}$-$^{14}\mathrm{N}$, $^{16}\mathrm{O}$-$^{15}\mathrm{N}$, $^{16}\mathrm{O}$-$^{16}\mathrm{O}$, $^{16}\mathrm{O}$-$^{18}\mathrm{O}$, and $^{18}\mathrm{O}$-$^{18}\mathrm{O}$ have been subjected to comparative optical-model analyses. The gross structure characteristic of all these excitation functions is shown to arise from potential scattering phenomena. These phenomena have been studied in detail. The extracted $^{16}\mathrm{O}$-$^{16}\mathrm{O}$ potential has been used as input to detailed studies leading to the identification of single partial-wave orbiting resonances of 3- to 4-MeV width. The $^{16}\mathrm{O}$-$^{16}\mathrm{O}$ experimental data have also been used to test for the possible existence of a variable-moment-of-inertia effect during the interpenetrating collisions; no evidence for such an effect has been found, at least in this particular case. New suggestions for the prediction of the imaginary optical-potential parameters have been investigated.