Allowance for the orientation of colliding ions in describing the synthesis of heavy nuclei

The dynamical model proposed earlier for describing fusion-fission reactions was modified in order to take into account an arbitrary orientation of colliding ions. In this model, the evolution of collective coordinates of the system under study is treated as a two-stage process. The motion of the projectile nucleus toward the target nucleus is considered at the first stage, and the evolution of a continuous dinuclear system formed as soon as the projectile and target nuclei touch each other is calculated at the second stage. At either stage of the calculation, the dynamical evolution of the system is described in terms of Langevin equations. The shell structure of the nuclei involved is taken into account at both stages. The difference between the results obtained for the first stage with allowance for an arbitrary orientation of colliding ions and the respective results for the case where their symmetry axes are aligned are discussed. The cross sections for the touching of primary nuclei and for their fusion are calculated, along with the cross sections for evaporation-residue formation in reactions involving nuclei that are prolate and spherical in the ground state. The results are compared with available theoretical and experimental data.