Angular distributions were measured for the (${\mathrm{O}}^{16}$, ${\mathrm{C}}^{12}$) reactions on ${\mathrm{Mg}}^{24,26}$, ${\mathrm{Al}}^{27}$, and ${\mathrm{Si}}^{28}$ at 42 MeV. States in the "$\alpha$-particle" nuclei ${\mathrm{Si}}^{28}$ and ${\mathrm{S}}^{32}$ were populated strongly for $0<~E_x<~11$ MeV, while cross sections for transitions to states in ${\mathrm{Si}}^{30}$ and ${\mathrm{P}}^{31}$ were small. The ${\mathrm{Si}}^{28}$ and ${\mathrm{S}}^{32}$ ground-state angular distributions are sharply oscillatory in nature. The 4.43-MeV state of ${\mathrm{C}}^{12}$ is strongly excited in the reaction ${\mathrm{Mg}}^{24}$(${\mathrm{O}}^{16}$, ${\mathrm{C}}^{12}$)${\mathrm{Si}}^{28}$, but not in the others.

• Received 2 June 1972

DOI:https://doi.org/10.1103/PhysRevLett.29.291