Evidence for transparency in medium-energy composite-projectile nucleus collisions

We compare total reaction cross sections found in proton and composite-projectile (d and ) collisions with C12, O16, and Ca40 target nuclei at incident energies between 5 and 600 MeV/nucleon. The energy dependence of the composite-projectile R values is found to be as large as or larger than for protons. A simple semiclassical analysis suggests that, at Ec.m./nucleon of approximately 250 MeV, composite-projectile collisions are, in effect, more transparent than proton collisions with the same target nucleus.