Transition between Light- and Heavy-Ion Elastic Scattering

We have measured the elastic scattering from ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ of 135.1-MeV ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and 186-MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions. The shapes of the angular distributions and the resultant optical-model analyses indicate that ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ scattering is quite similar to that of light ions, while ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions behave like heavier ions. Thus there appears to be a pronounced and quite rapid transition of scattering characteristics with projectile mass.