Fusion of heavy nuclei

Abstract

Cross sections for evaporation residue formation following complete fusion of $^{81}\mathrm{Br}$+$^{90,94}\mathrm{Zr}$, $^{96}\mathrm{Mo}$, and $^{104}\mathrm{Ru}$ and $^{90}\mathrm{Zr}$+$^{90,94}\mathrm{Zr}$ have been measured over a broad range of energies from far below to well above the classical Coulomb barrier. We observe large changes of slope and magnitude among the excitation functions for these systems at all energies. There are pronounced structural variations at sub-barrier energies, less rapid than expected increases in evaporation residue formation at near-barrier energies and declining evaporation residue formation as the systems become heavier at still higher energies.