Elastic scattering, transfer reactions, and fission induced by O-16 ions on Ta-181 and Pb-208

Total cross sections for the quasielastic and fission channels in reactions of /sup 16/O on /sup 181/Ta and /sup 208/Pb were measured as a function of the incident energy near the Coulomb barrier. For /sup 208/Pb, the fission and quasielastic components account for essentially all of the total reaction cross sections as deduced from the elastic scattering. However, for /sup 181/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 /sup 208/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 /sup 181/Ta are described reasonably well by a statistical evaporation code.