The partial production cross sections for 11 nuclides produced in the fusion of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, in the energy region from 17-28 MeV (c.m.), have been measured and compared to an evaporation-model calculation. The comparison, though not completely satisfactory, provides no evidence that such models are inadequate to explain the observations. The "effective" $\alpha$-particle evaporation yield, deduced from measured partial production cross sections, is shown to be in excellent agreement with previously measured $\alpha$-particle yields up to 26 MeV (c.m.). The implications of this agreement for the apparent discrepancies between heavy-particle and $\gamma$-ray measurements of the fusion yield are discussed. The average total fusion yield, including $3\alpha$ evaporation to ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, is found to be nearly constant at about 1 barn from 20-26 MeV (c.m.). Narrow, regular fluctuations in the yield, with a periodicity of 725 keV and an average width of 150-200 keV are observed. These anomalies are correlated in the various partial-production excitation functions. It is found, however, that the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ excitation functions are anticorrelated and possible explanations for this latter observation are discussed.

NUCLEAR REACTIONS Complete fusion, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=17-28\mathrm{}$ MeV; evaporation model analysis of nuclide distributions: correlation analysis of fluctuations.

• Received 5 July 1978

DOI:https://doi.org/10.1103/PhysRevC.19.408