Elastic and inelastic scattering of 16O and 18O ions from 64Zn at energies near the Coulomb barrier.

Abstract

Coulomb-nuclear interference effects were investigated in the inelastic scattering of [sup 16]O and [sup 18]O by [sup 64]Zn. Measurements of elastic and inelastic angular distributions of [sup 18]O were performed at a laboratory energy of 49 MeV, over the angular range from [theta][sub lab][similar to]30[degree] to 85[degree]. The excitation functions of [sup 16]O and [sup 18]O ions were measured at incident energies between 29 and 46 MeV at [theta][sub lab]=174[degree]. The experimental angular distributions show structures which are more pronounced for projectile excitation than for target excitation. The interference minimum for the excitation of the [sup 18]O first 2[sup +] state was found to be shifted towards forward angles by approximately 5[degree] (c.m.) with respect to the distorted-wave Born approximation calculations and by approximately 3.5[degree] (c.m.) with respect to the coupled-channels calculations. A pronounced Coulomb-nuclear interference minimum was seen in the excitation of [sup 64]Zn(2[sup +]) state by inelastic scattering of [sup 16]O projectiles, whereas no pronounced minimum was observed in target excitation by [sup 18]O projectiles. The elastic scattering data were analyzed with the optical model. The inelastic differential cross sections for the excitation of the first 2[sup +] states in the target and in the [sup 18]O projectilemore » were analyzed using the distorted-wave Born approximation and also the coupled-channels approach with collective form factors.« less