The back-angle yields of the oxygen and carbon particles from the ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$+${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ reaction have been measured at $E_{\mathrm{lab}}\left({}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}\right)=79.5\mathrm{}$ MeV by using reverse kinematics. Comparison with data for the ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$+${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ reaction forming the same compound nucleus at the same excitation energy and with very similar spin distribution, demonstrates a strong entrance channel effect which is favorin the breakup into the entrance channel with large excitation energy. This result qualitatively supports the picture of the formation of a long-lived orbiting complex whose structure and decay is dependent on the entrance channel. The compound nucleus contribution is inferred to be less than 15% of the measured oxygen cross section.

• Received 21 December 1984

DOI:https://doi.org/10.1103/PhysRevC.31.1573