Deduction of compound nucleus formation probability from the fragment angular distributions in heavy-ion reactions

Abstract

The presence of various fissionlike reactions in heavy-ion induced reactions is a major hurdle in the path to laboratory synthesis of heavy and super-heavy nuclei. It is known that the cross section of forming a heavy evaporation residue in fusion reactions depends on the three factors---the capture cross section, probability of compound nucleus formation ${P}_{\mathrm{CN}}$, and the survival probability of the compound nucleus against fission. As the probability of compound nucleus formation, ${P}_{\mathrm{CN}}$ is difficult to theoretically estimate because of its complex dependence on several parameters; attempts have been made in the past to deduce it from the fission fragment anisotropy data. In the present work, the fragment anisotropy data for a number of heavy-ion reactions are analyzed and it is found that deduction of ${P}_{\mathrm{CN}}$ from the anisotropy data also requires the knowledge of the ratio of relaxation time of the $K$ degree of freedom to pre-equilibrium fission time.