${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^9{}_{}{}^{}\mathrm{Be}$,${}_{}{}^9{}_{}{}^{}\mathrm{Be}$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(g.s., 4.43 MeV) reaction

Angular distributions for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^9{}_{}{}^{}\mathrm{Be}$,${}_{}{}^9{}_{}{}^{}\mathrm{Be}$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(g.s.,4.43 MeV) reaction have been measured at ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ bombarding energies of 39.68 and 43.75 MeV over an angular range from 13° to 158° c.m. Back angle cross section enhancements were observed in both the elastic and 4.43 MeV channels. The enhancement of the back angle elastic cross section could not be described in terms of a simple optical model or coupled channels analysis. In an attempt to explain these back angle data, several reaction mechanisms were investigated. The importance of heavy ion resonance formation was determined from an excitation function measured in 200 keV intervals from 40 to 45 MeV at 158° c.m. A Hauser-Feshbach calculation was used to place an upper limit on the statistical compound nuclear contribution to the cross section. Finally, an exchange calculation in which a ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ cluster was transferred between the two ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ cores has been made.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^9{}_{}{}^{}\mathrm{Be}$,${}_{}{}^9{}_{}{}^{}\mathrm{Be}$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ (g.s., 4.43 MeV); measured $\sigma \left(\theta \right)$, $\theta =13-158\mathrm{}°$ c.m. at 39.68 and 43.75 MeV and $\sigma \mathrm{}\left(E\right)=40-45\mathrm{}$ MeV, $\Delta E=200\mathrm{}$ keV; deduced reaction mechanism. Enriched targets. Hauser-Feshbach, coupled channels, and exchange analysis.