Resonancelike structures have been seen in the excitation functions for fusion in light "$\alpha$-particle" nuclei, with spacings of about 5 MeV and widths of about 2 MeV. These have been reported in systems as heavy as ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$+${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, but were not found in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$. A search for similar structure was made for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ system, in steps of 350 keV from $40 \mathrm{MeV}\le E_{\mathrm{lab}}\left({}_{}{}^{16}{}_{}{}^{}\mathrm{O}\right)\lesssim 51 \mathrm{MeV}$, by observing the $\gamma$-ray yields of specific residues. While there is evidence for weak structure in the yields of some residues, cross-correlation analysis indicates that no correlated structure exists at the statistical accuracy of the present data (≲5%).

NUCLEAR REACTIONS ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, $E_{\mathrm{lab}}=40-51\mathrm{}$ MeV; measured ${\sigma }_{\mathrm{fusion}}\mathrm{}\left(E\right)\mathrm{}$ of residues; correlation analysis of data.

• Received 21 June 1982

DOI:https://doi.org/10.1103/PhysRevC.26.2022