Residues following ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{12}$C fusion were identified by their characteristic γ rays. For several transitions in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{25}{}_{}{}^{}\mathrm{Mg}$, and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$, coincident neutron spectra were measured at six angles. Through use of an evaporation code, comparisons were made of these spectra with predictions of the statistical model at five ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ projectile energies between 43.2 and 56.0 MeV. The result requires an excitation energy dependence for the effective radius parameter $r_0$, which determines the spin cutoff factor.

• Received 19 November 1984

DOI:https://doi.org/10.1103/PhysRevC.31.858