Proton radiative capture into closed-shell and closed-shell-plus-one-proton nuclei

Radiative proton capture reactions into nuclei with closed subshells and into the neighboring nuclei with one additional proton produce gamma-ray spectra with remarkably similar major features. Detailed measurements of B11(p,)C12 and C12(p,)N13, described here, reveal additional striking similarities. A generalized direct-semidirect picture of the reaction is presented, from which quantitative relationships between such capture reaction pairs may be derived, including comparisons of angular distributions, analyzing powers, and cross-section ratios over a wide range of bombarding energies. The data are in good agreement with the theoretical predictions.