It has been found that the fraction of the reaction cross section diverted to complete fusion of light heavy ions is strongly correlated to the nucleon (cluster) separation energy of the participants. The presence of weakly bound nuclei hinder the fusion cross section indicating that they do not survive the collision long enough in order to contribute significantly to the fusion process. Model calculations support this picture. The ${}_{}{}^{38}{}_{}{}^{}\mathrm{Ar}$ compound nucleus populated by entrance channels with different mass asymmetries, i.e., ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$${+}^{29}$Si, ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$${+}^{27}$Al, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{26}$Mg, and ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$${+}^{19}$F, has been investigated, supporting the mentioned correlation. Consequence of this effect in the fusion cross section of exotic nuclei is discussed.

• Received 23 March 1992

DOI:https://doi.org/10.1103/PhysRevC.46.1139