Systematics of precise nuclear fusion cross sections: The need for a new dynamical treatment of fusion?

A large number of precision fusion excitation functions, at energies above the average fusion barriers, have been fitted using the Woods-Saxon form for the nuclear potential. Values of the empirical diffuseness parameter greatly exceed those which generally reproduce elastic scattering data and tend to increase strongly with the reaction charge product Z₁Z₂. Possible reasons for this may lie in the Woods-Saxon form being inappropriate, or in the reduction of fusion cross sections by processes such as deep-inelastic collisions. These results point to a need for renewed efforts in dynamical calculations of fusion.