The nuclear reactions ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, \alpha ){}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, p){}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ have been observed from 5-MeV down to 2.45-MeV center-of-mass energy. Angular distributions and energy distributions of the protons and $\alpha$ particles were analyzed to obtain the total cross sections and other nuclear information. The Coulomb and angular momentum barrier penetrability was factored out to elucidate the intermediate resonance structure in the nuclear factor $\tilde{S}$. The observed rise in the nuclear factor at the lowest energies may be interpreted as "absorption under the barrier" as proposed by Michaud and Vogt. The importance of these reactions for the carbon burning era of nucleosynthesis and energy generation in the later evolution of stars is mentioned and reaction rates are estimated for various burning temperatures.

• Received 21 October 1972

DOI:https://doi.org/10.1103/PhysRevC.7.1280