Fission-to-spallation ratio and fission dynamics manifestation

Fission of highly excited nuclei is affected by the viscous character of the system motion in deformation coordinates for very heavy nuclei with Z ≥ 90. The long-time scale fission was proved for such systems formed in heavy-ion induced reactions. The overdamped diabatic motion may influence also fission of the spallation-residue products in reactions with protons at intermediate energy. The experimental results on fission-to-spallation ratio are analyzed and the evidences for the long-time scale fission are found in the fission excitation functions for medium-mass targets with Z=70-75