Compound-Nucleus Decay along the Mass-Asymmetry Coordinate and the Role of the Businaro-Gallone Point

Fragments with atomic numbers covering the entire range of the mass-asymmetry coordinate (Z = 1 to Z = Z/sub CN//2) were observed from the decay of compound nuclei (CN) produced in reactions of 7.4- and 8.4-MeV/nucleon /sup 74/Ge, /sup 93/Nb, and /sup 139/La with /sup 9/Be and /sup 12/C. The evolution of the charge distribution with increasing mass of the compound nucleus (A = 83 to 151) reflects the topological change in the potential-energy surface associated with crossing the Businaro-Gallone point. 7 references, 4 figures, 1 table.