Total fusion cross sections for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$, and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ have been measured in the energy range $18 \mathrm{MeV}\le E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\le 50 \mathrm{MeV}$ by detection of the evaporation residues. In addition, elastic scattering angular distributions have been measured and analyzed with the optical model. The fusion cross section for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ saturates at ∼ 1100 mb, while that for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ reaches ∼ 1200 mb. The fusion cross section excitation functions can be well described by the model of Glas and Mosel using reasonable parameters; the model of Bass reproduces the data well above $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\approx 25$ MeV but overpredicts the cross section below this energy.

NUCLEAR REACTIONS ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, $E_{\mathrm{lab}}=30\mathrm{}-81$ MeV; ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$, $E_{\mathrm{lab}}=29.4\mathrm{}-81$ MeV; ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, $E_{\mathrm{lab}}=32\mathrm{}-72$ MeV; measured ${\sigma }_{\mathrm{fusion}}$; measured $\sigma \left(\theta \right)$ elastic scattering; deduced optical-model parameters.

• Received 9 January 1978

DOI:https://doi.org/10.1103/PhysRevC.17.2136