Is Fusion Inhibited for Weakly Bound Nuclei?

Complete fusion of light radioactive nuclei is predicted to be hindered at near-barrier energies. This feature is investigated in the case of the least bound stable nuclei. Evaporation residues resulting from the ${}^{6,7}\mathrm{Li}{+}^{9}\mathrm{Be}$ and ${}^{6,7}\mathrm{Li}{+}^{12}\mathrm{C}$ fusion reactions have been measured in order to study common features in reactions involving light weakly bound nuclei. The experimental excitation functions revealed that the fusion cross section is significantly smaller than the total reaction cross section and also smaller than the fusion cross section expected from the available systematics. A clear correlation between the fusion probability and nucleon (cluster) separation energy has been established. The results suggest that the breakup process has a strong influence on the hindrance of the fusion cross section.