A very narrow $3^{-}$ level has been predicted to be nearly degenerate with the known $2^{+}$ state at 9.85 MeV in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. The elastic scattering of $\alpha$ particles from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ has been reexamined in the region of 9.85 MeV excitation in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, and it is found that the data are well described by a calculation which assumes that only the known $2^{+}$ state is present. Calculations show that a $3^{-}$ resonance having ${\Gamma }_{\mathrm{lab}}\lesssim 150$ eV could have escaped detection if it was a few keV higher in energy than the $2^{+}$ resonance. A $3^{-}$ resonance lying anywhere else in the energy range examined would have to have ${\Gamma }_{\mathrm{lab}}<100\mathrm{}$ eV.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}+\alpha$ elastic scattering, $E_{\alpha }=3.52-3.62\mathrm{}$ MeV, ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=90\mathrm{}°-173.3\mathrm{}°$; $R$-matrix theory analysis.

• Received 26 October 1981

DOI:https://doi.org/10.1103/PhysRevC.25.2935