Attempts for synthesizing superheavy elements have to overcome
the fusion hindrance as the large Coulomb repulsion of colliding system
and the dissipation of the kinetic energy due to the strong nuclear friction. To
describe the fusion-fission process and to estimate the possibility of synthesis
of superheavy elements, the dynamical model based on fluctuation-dissipation
theorem has been applied. The theory of Brownian motion is employed to describe
the dynamical evolution of the whole fusion-fission process, with extremely
small probability of residues of superheavy nuclei. First, as diffusion model, onedimensional
Smoluchowski equation was applied, which taking account of the
temperature dependence of the shell correction energy. A new mechanism for an
optimum condition was found as a compromise of two conflicting requirements:
higher incident energy for larger fusion probability and lower excitation energy
of compound nuclei for larger survival probability. To describe fusion-fission
process more realistically, the three-dimensional Langevin equation was applied.
Using the model, we estimated the possibility of synthesis of superheavy elements
and clarified the fusion-fission mechanism. We present these developments and
main results.
Keywords: superheavy elements, dynamical model, diffusion model, Langevin equation
