Elastic scattering, transfer reactions, and fission induced byO16ions onTa181andPb208

Abstract

Total cross sections for the quasielastic and fission channels in reactions of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ on ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ were measured as a function of the incident energy near the Coulomb barrier. For ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, the fission and quasielastic components account for essentially all of the total reaction cross sections as deduced from the elastic scattering. However, for ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$, the fission and quasielastic components account for only about 25% of the total cross section as deduced from elastic scattering. The fission fragment angular distributions for ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ are analyzed with a simple statistical approach yielding an effective moment of inertia at the saddle point compatible with the liquid-drop-model prediction. Fission excitation functions for ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ are described reasonably well by a statistical evaporation code.