Symmetric splitting for the system ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$${+}^{238}$U at energies near and below the barrier

The total capture cross section for the system ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$${+}^{238}$U has been measured at energies from 0.93 to 1.08 times the s-wave interaction barrier by detecting coincident fission fragments following full momentum transfer reactions. The subbarrier cross section cannot be reproduced by a one-dimensional barrier penetration model. Using a quantum mechanical coupled channels model, good agreement is obtained. The measured angular distributions of fission fragments were compared to the predictions of saddle and scission point transition state theory. Saddle point transition state model calculations fail to reproduce the data, while scission point transition state calculations are in agreement with their qualitative trend. Evidence for nonequilibrium processes is presented.