Dip in theC12(C12,α)Ne20cross section atEc.m.=19.2MeV

Abstract

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.