Role of the orientation angles of reacting nuclei in evaporation residue production

The influence of the orientation angles of the projectile- and target-nucleus symmetry axes relative to the beam direction on the production of the evaporation residues (ERs) is investigated for the 48Ca+154Sm reaction as a function of the beam energy. The measured yields of ERs by massive nuclei reactions have been well reproduced by using the partial fusion and quasi-fission cross-sections obtained in the dinuclear system model. At lower beam energies, only the orientation angles close to P=30 (projectile) to P=0-15(target) can contribute to the ER formation. At large beam energies (about Ec.m.=140-180MeV), all P-T configurations of reactants can contribute to the ER cross-section, which ranges between 10 and 100mb, while at Ec.m.185MeV, the ER cross-section ranges between 1 and 0.1mb because the fission barrier for the compound nucleus decreases by increasing its excitation energy and angular momentum.