Using the 31.5-Mev alpha-particle beam of the Massachusetts Institute of Technology cyclotron, a study has been made of the angular distributions obtained in the ($\alpha , \alpha$) and ($\alpha , {\alpha }^{\prime }$) interactions on ${\mathrm{Li}}^6$, ${\mathrm{C}}^{12}$, and ${\mathrm{Mg}}^{24}$. Separation of the alpha particles from other products of the alpha-induced reactions was accomplished by a $\frac{\mathrm{dE}}{\mathrm{dx}}$ and $E$ two-crystal technique developed at the cyclotron laboratory. The experimental inelastic angular distributions are shown to be in agreement with those predicted by the direct surface interaction theory. The experimental elastic angular distributions are compared with the diffraction of light by an opaque sphere. The probabilities of excitation of isotopic spin "forbidden" and "allowed" levels were also obtained for specified levels of ${\mathrm{Li}}^6$ and ${\mathrm{N}}^{14}$.

• Received 21 March 1956

DOI:https://doi.org/10.1103/PhysRev.103.1763