Angular distributions of single pion charge exchange reactions to isobaric analog states in light nuclei

Measurements of the angular distributions of the single charge exchange reactions to isobaric analog states for /sup 13/C(..pi../sup +/,..pi../sup 0/)/sup 13/N and /sup 15/N(..pi../sup +/,..pi../sup 0/)/sup 15/O at 165 MeV are described. The two angular distributions are very similar. The shapes are reproduced by semiphenomenological isobar-doorway calculations and by second-order coupled channels calculations. The calculated magnitudes are low by about a factor of 2. Phenomenological calculations that agree with small-angle excitation functions do not reproduce the angular distributions. The measurements are consistent with older angle-integrated cross sections for /sup 13/C.