Mechanisms producing fissionlike binary fragments in heavy ion collisions

The mixing of the quasifission component to the fissionlike cross section causes ambiguity in the quantitative estimation of the complete fusion cross section from the observed angular and mass distributions of the binary products. We show that the partial cross section of quasifission component of binary fragments covers the whole range of the angular momentum values leading to capture. The calculated angular momentum distributions for the compound nucleus and dinuclear system going to quasifission may overlap: competition between complete fusion and quasifission takes place at all values of initial orbital angular momentum. Quasifission components formed at large angular momentum of the dinuclear system can show isotropic angular distribution and their mass distribution can be in mass symmetric region similar to the characteristics of fusion-fission components. As result the unintentional inclusion of the quasifission contribution into the fusion-fission fragment yields can lead to overestimation of the probability of the compound nucleus formation. (author)