Measurements have been made of the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(\alpha , {\alpha }^{\prime }){}_{}{}^{16}{}_{}{}^{}\mathrm{O}_{}^{*}{}_{}{}^{}\left(9.85\mathrm{} \mathrm{MeV}\right)\left({\alpha }_0\right){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ angular correlation at seven energies between $E_{\alpha }=23.0\mathrm{} \mathrm{and} 27.5$ MeV. The study was undertaken to search for evidence of a $3^{-}$ state which has been predicted to be nearly degenerate with the known $2^{+}$ state at 9.85 MeV excitation in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. All of the results indicate that the reaction proceeds entirely through a $2^{+}$ state in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. Since there is evidence that the initial stage of the reaction is not selective, the present results argue against the existence of the predicted $3^{-}$ state.

NUCLEAR REACTIONS ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(\alpha , {\alpha }^{\prime })$, $E_{\alpha }=22.0-27.5\mathrm{}$ MeV, $\theta =170\mathrm{}°$; ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(\alpha , {\alpha }^{\prime }){}_{}{}^{16}{}_{}{}^{}\mathrm{O}_{}^{*}{}_{}{}^{}\left(9.85\mathrm{} \mathrm{MeV}\right)\left({\alpha }_0\right){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, $E_{\alpha }=23.0-27.5\mathrm{}$ MeV, $\theta \left({\alpha }^{\prime }\right)=180\mathrm{}°$; measured angular correlation at seven energies; deduced $J^{\pi }$.

• Received 4 March 1983

DOI:https://doi.org/10.1103/PhysRevC.27.2482