STUDY OF THE REACTIONS OCCURRING IN THE FUSION OF C-12 AND O-16 WITH HEAVY-NUCLEI AT INCIDENT ENERGIES BELOW 10 MEV NUCLEON/

The excitation functions for production of many residues in the fusion of C-12 With Ta-181 and Au-197 and of O-16 with Ho-165 and Ta-181 hav e been measured at incident energies varying from the Coulomb barrier up to about 10 MeV/nucleon. The cross sections for fusion of these ion s without fission have been deduced and they show that such a process may only occur for projectile angular momenta smaller than a critical value. The excitation functions for individual reactions provide evide nce for the emission of preequilibrium nucleons during the thermalizat ion of the composite nucleus and may be satisfactorily reproduced by a calculation based on the Boltzmann master equation theory.