Observed transitions in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({\pi }^{+}, p){}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ at 49.3 MeV confirm the importance of multistep processes in the reaction mechanism. The relative intensity of the transitions is nearly the same as in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, d){\mathrm{C}}^{11}$ at 700 MeV, except for an apparent isospin selection rule. Transitions to low-lying states in ${}_{}{}^{10}{}_{}{}^{}\mathrm{C}$ via the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({\pi }^{+}, d)$ have also been observed.

• Received 2 February 1978

DOI:https://doi.org/10.1103/PhysRevLett.40.758