  The multinucleon transfer process is one promising approach for producing
neutron-rich heavy nuclei. The favorable projectile-target combinations play a
key role in experiments. As one important approach to investigate the
multinucleon transfer process, one new version of the dinuclear system (DNS)
model is developed. The improved version of the DNS model is shown in detail.
Based on deformation degree of freedom in the improved DNS model, one way of
calculating excitation energies of primary fragments is proposed. And the
remarkable improvements for describing experimental data of producing
trans-uranium nuclei is noticed. To produce trans-uranium nuclei, the
collisions of 48Ca, 136Xe, and 238U projectiles with the 238U target are
investigated within the improved DNS model. Based on the potential energy
surface, the influence of projectiles on the probabilities of transferring
neutrons and protons from the projectiles to the target are studied. One
behavior is found that the transfer probabilities strongly depend on the
projectiles in the neutron stripping process, while relatively weak projectile
dependence is noticed in the proton transferring process. The 136Xe and 238U
projectiles show great advantages of cross sections for producing neutron-rich
trans-uranium nuclei, although the fission probabilities are large.
