The ratio of cross sections for nucleon knockout by pions, e.g. $\frac{\sigma \left[{}_{}{}^{12}{}_{}{}^{}\mathrm{C}\right({\pi }^{-}, \pi N\left){}_{}{}^{11}{}_{}{}^{}\mathrm{C}\right]}{\sigma \left({}_{}{}^{12}{}_{}{}^{}\mathrm{C}\right({\pi }^{+}, \pi N\left){}_{}{}^{11}{}_{}{}^{}\mathrm{C}\right]}$, is shown to be insensitive to pion charge exchange either before or after the knockout collision.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({\pi }^{\pm }, \pi N)$, $T_{\pi }=50-300\mathrm{}$ MeV; ratio of $\sigma \left(T_{\pi }\right)\text{'}\mathrm{s}$; pion charge exchange effects.

• Received 10 April 1975

DOI:https://doi.org/10.1103/PhysRevC.12.341