THE STUDY OF FUSION-FISSION AND QUASIFISSION PROCESSES IN THE REACTIONS 48Ca+208Pb, 232Th, 238U, 244Pu, 248Cm
Mass-energy distributions and capture cross sections have been measured in the reactions 48Ca + 208Pb, 232Th, 238U, 244Pu, and 248Cm at energies around the Coulomb barrier. The properties of the fusion-fission and quasifission processes were studied in dependence on the interaction energies and ion-target combinations. In the reaction 48Ca+208Pb the fusion-fission process is dominant. In the reactions of 48Ca with actinide targets the asymmetric quasifission becomes the dominant process. Nevertheless, the analysis of mass and energy distributions has shown that a significant part of symmetric fragments in the range ACN/2 ± 20 u may be attributed to fusion-fission process for the reactions 48Ca+238U, 244Pu, and 248Cm. Using this analysis we estimated the fusion-fission crosssections σFF, the survival probabilities Wsur and the lower limits for fission barriers of 254-256No, 283-286Cn, 289-292Fl, and 293-296Lv compound nuclei.