Isotopic dependence of the evaporation residue cross section in the synthesis of superheavy nuclei

The formation of superheavy nuclei via hot fusion reactions Ca-48+Ra-A and Ca-48+Th-A is systematically studied within the diffusion model. The effect of the isotopic composition of actinide target on the production cross section is analyzed in detail. The results show that, as a general trend, the evaporation residue cross section exponentially depends on the difference of the effective fission barrier hight and neutron separation energy in units of the temperature. By means of this exponential relationship, the possible optimal isotopic composition of the colliding nuclei can be easily figured out before the experiment.