Entrance-Channel Effects in theS32System: Comparison ofC12+Ne20andO16+O16Elastic Scattering

Abstract

${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ elastic-scattering angular distributions have been measured at several energies, and an excitation function has been obtained at 70° center of mass from $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=17\mathrm{} \mathrm{to} 2.8$ MeV. The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ data are greatly damped compared with ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ data in this energy range. This demonstrates that the absorption is not determined primarily by compound-nuclear properties. The differences are interpreted in terms of the more favorable angular-momentum matching conditions for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ direct-reaction channels.