Formation of transfermium elements in reactions with Pb208

Within the Langevin framework, we investigate the dynamics of the fusion process for production of transfermium elements in reactions of ${}^{48}\mathrm{Ca}$, ${}^{50}\mathrm{Ti}$, ${}^{54}\mathrm{Cr}$, and ${}^{58}\mathrm{Fe}$ with ${}^{208}\mathrm{Pb}$. After the reacting nuclei have made contact, the early dynamical stage is dominated by the dissipation of the initial radial kinetic energy, while the subsequent shape evolution is diffusive. The probability for surmounting the inner barrier and forming a compound system is obtained by simulating the evolution as a Metropolis random walk in a five-dimensional potential-energy landscape. Good agreement with the available data is obtained, especially for the maximal formation probability.