INCLUSIVE SYSTEMATICS FOR SI-28+SI-28 REACTIONS BETWEEN 20 AND 35 MEV PER NUCLEON

Inclusive velocity spectra of heavy ions produced in the Si-28 + Si-28 reaction at 22, 26, 30, and 35 MeV per nucleon were measured and decomposed into peripheral and central components using an analytical moving-source parametrization. The persistence of incomplete fusion followed by evaporation has been observed over the entire bombarding energy range. Ratios of parallel and perpendicular momentum widths for fusion events show a growth of preequilibrium emission with increasing beam energy. The evaporation-residue data are consistent with a limit of 6 MeV per nucleon excitation energy beyond which conventional evaporation becomes significantly less probable. This limiting value is compatible with what one can expect from the balance between nuclear relaxation times and times for particle evaporation