Production of evaporation residues in the O-16 + Pb-208 and Ca-48 + Yb-176 reactions

Cross section data for evaporation residues (ERs) produced in the O-16 + Pb-208 and Ca-48 + Yb-176 heavy-ion fusion-evaporation reactions leading to the same Th-224* compound nucleus (CN) were obtained at energies around the fusion reaction barriers with the recoil separator VASSILISSA. These data for ERs formed in the most probable evaporation channels in both reactions agree with those obtained earlier. ER and fission cross sections for O-16 + Pb-208 are well reproduced with model calculations using adjustment of respective model parameters. The mutual comparison of the ER cross sections for the very asymmetric (O-16 + Pb-208) and more symmetric (Ca-48 + Yb-176) projectile-target combinations allowed us to obtain the fusion probability value (CN formation probability) imposed by the quasifission effect inherent in the Ca-48 + Yb-176 reaction.