Differential scattering cross sections for the elastic and first excited state inelastic scattering of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ from ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ have been measured at ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ laboratory bombarding energy of 33, 36, and 38 MeV and at an ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ bombarding energy of 36 MeV. The experimental results have been analyzed in terms of coupled channels on the basis of a rotational model. For ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ projectiles the deformation of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ was found by this technique to be ${\beta }_2=-0.30\mathrm{}\pm 0.08$ and ${\beta }_4\ge +0.1\mathrm{}$. The cross sections for the scattering of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ by ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ could not be described with the deformation parameters obtained from the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ scattering data. The present results are compared with recent experiments using different projectiles and with the results of recent theoretical calculations.

• Received 21 July 1972

DOI:https://doi.org/10.1103/PhysRevC.7.1950