In most of the excitation functions for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},\alpha ){}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ reaction to levels of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ below $E_x=17\mathrm{}$ MeV, a pronounced minimum occurs at a center-of-mass (c.m.) bombarding energy of 19.2 MeV. The c.m. width is 400-500 keV. This structure is very likely due to the resonance reported by Van Bibber et al. in the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},p){}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ reaction at an energy of 19.3 MeV, with a width of ∼500 keV.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},\alpha )$, $E=36\mathrm{}-51$ MeV. Measured $\sigma \mathrm{}\left(E\right)\mathrm{}$ at $\theta =5\mathrm{}°$ (lab) for 22 levels.

• Received 15 April 1974

DOI:https://doi.org/10.1103/PhysRevC.10.1211