The intensity ratio of the ground state ($2^{-}$) to the 0.30 MeV ($3^{-}$) state of ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ as measured in the ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(d,{}_{}{}^3{}_{}{}^{}\mathrm{He})$ reaction and the intensity ratio of their analog states at 12.97 and 13.26 MeV in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ as measured in the ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(d,t)$ and ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}({}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha )$ reactions consistently differ by about 50%. A largely model independent analysis of this isospin mixing effect in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ suggests ≥ 17% mixing of the $2^{-}$ states at 12.97 ($T=1\mathrm{}$) and 12.53 MeV ($T=0\mathrm{}$) as its dominant source, in which case a lower limit of the isospin mixing matrix element of (155 ± 30) keV is obtained.

NUCLEAR REACTIONS ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(d,{}_{}{}^3{}_{}{}^{}\mathrm{He})$, ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(d,t)$, $E=52\mathrm{}$ MeV; ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}({}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha )$, $E=36\mathrm{}$ MeV. Measured $\sigma \left(\theta \right)$ and relative population of the ground state ($2^{-}$) and the 0.30 MeV ($3^{-}$) state of ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$, and their analog states in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ at 12.97 and 13.26 MeV, respectively.

NUCLEAR STRUCTURE ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, deduced isospin mixing of the $2^{-}$ states at 12.97 MeV ($T=1\mathrm{}$) and 12.53 MeV ($T=0\mathrm{}$).

• Received 1 June 1977

DOI:https://doi.org/10.1103/PhysRevC.16.1271