Elastic and Inelastic Scattering of Protons by Carbon-12 for Proton Energies between 18 and 30 MeV

Abstract

Differential cross sections for elastic scattering of protons by ${\mathrm{C}}^{12}$ have been measured for incident proton energies between 18 and 30 MeV. Angular distributions were obtained for proton energies of 20.0, 21.6, 24.1, 26.1, and 27.8 MeV. The elastic differential cross section as a function of energy for center-of-mass angles of 46.7°, 60.6°, 135.0°, and 145.0° was investigated for incident energies between 17.6 and 30.4 MeV. Absolute angular distributions and integrated partial cross sections for proton scattering leading to the excitation of the 4.4-, 7.7-, 9.6-, and 12.7-MeV levels in ${\mathrm{C}}^{12}$ are reported. The angular distributions of the elastically scattered protons are strongly energy-dependent over the studied energy interval. The inelastic angular distributions do not exhibit such a marked energy dependence and are peaked forward for all levels studied. The angular distributions of protons inelastically scattered from the 4.4-MeV level are compared with the predictions of the zero-range, plane-wave Born-approximation direct-interaction theory.