A careful survey has been made of the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ fusion cross section from $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=12\mathrm{} \mathrm{to} 20$ MeV in order to determine which resonances in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ appear strongly in the total fusion cross section. Resonances which contribute 60-80 mb to the total fusion cross section are observed at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=13.15, 14.7, 18.0, \mathrm{and} 18.5$ MeV. An additional six resonances which contribute 30-50 mb are observed. The resonances have widths in the range 150-300 keV. All appear to correspond to resonances which have been reported previously from studies of individual reaction channels.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$,$X$), $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=12-20\mathrm{}$ MeV, measured $\sigma (A,\theta ,E)$ for $A>\mathrm{}16\mathrm{}$; deduced ${\sigma }_{\mathrm{fusion}}\mathrm{}(A,E)\mathrm{}$; observed resonances.

• Received 13 August 1981

DOI:https://doi.org/10.1103/PhysRevC.25.860