Non-equilibrium versus equilibrium emission of complex fragments from hot nuclei

The relative contributions of equilibrium and non-equilibrium mechanisms for intermediate-mass fragment emission have been deduced for Z=3-14 fragments formed in 3He- and 14N-induced reactions on Ag and Au targets. Complete inclusive excitation function measurements have been performed for 3He projectiles from E/A=67 to 1,200 MeV and for 14N from E/A=20 to 50 MeV. The data are consistent with a picture in which equilibrated emission is important at the lowest energies, but with increasing bombarding energy the cross sections are increasingly dominated by non-equilibrium processes. Non-equilibrium emission is also shown to be favored for light fragments relative to heavy fragments. These results are supported by coincidence studies of intermediate-mass fragments tagged by linear momentum transfer measurements