Exploitation of inverse reaction kinematics in a search for non-fusion yield in the heavy residue spectra of light heavy-ion reactions

The purpose of the present work was to subject the heavy residues which result from the 11B +12C interaction to a specific experimental test to determine whether or not the residues do indeed result from fusion-evaporation through the 23Na compound nucleus. Of particular concern is the possible presence of direct transfer and incomplete fusion strength. The test which is employed in the present work exploits the fact that in a nearly symmetric system such as 11B + 12C, the laboratory energy of the fusion products is essentially independent of which entrance channel nucleus is used as the target and which is used as the projectile, while the energy of direct transfer and incomplete fusion products depends strongly on which nucleus is the target or projectile. A careful, mass-by-mass comparison of the heavy residue energy spectra has been made for the two reactions 12C(11B,X) and 11B(12C,X). For the present experimental data, the systems leading to the 23Na compound nucleus, an accurate extraction of the fusion cross section is important as the authors can now clearly say that the fusion cross sections and, therefore, the critical angular momenta were correctly determined in earlier works. Therefore, a critical density of states can not be responsible for the limitations occurring in the entrance channels leading to the 23Na compound system