Ratios of cross sections for 200-MeV ${\pi }^{\pm }$ reactions on ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ leading to mirror levels in ${}_{}{}^{15}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$, observed by their $\gamma$ decays, were measured and compared. For the first ${\frac{3}{2}}^{-}$ levels, the ratios are ${\left(\frac{{}_{}{}^{15}{}_{}{}^{}\mathrm{O}}{{}_{}{}^{15}{}_{}{}^{}\mathrm{N}}\right)}_{{\pi }^{-}}=1.7\mathrm{}\pm 0.4$ and ${\left(\frac{{}_{}{}^{15}{}_{}{}^{}\mathrm{O}}{{}_{}{}^{15}{}_{}{}^{}\mathrm{N}}\right)}_{{\pi }^{+}}=\frac{1}{(1.8\mathrm{}\pm 0.4)}$, indicating charge symmetry.

• Received 22 January 1975

DOI:https://doi.org/10.1103/PhysRevLett.34.965