Energy Dependence of the Small-Angle Differential Cross Sections to Isobaric Analog States inLi7(π+, π0)Be7andC13(π+, π0)N13

The forward-angle differential cross sections of pion single charge exchange on $^{7}\mathrm{Li}$ and $^{13}\mathrm{C}$ were measured at 70, 100, 150, 165, and 180 MeV. The cross sections rise steeply up to 150 MeV and remain almost constant between 150 and 180 MeV. Comparisons with theoretical calculations and with the free charge-exchange cross sections are presented. There is poor agreement with the data. Only phenomenological calculations can fit the resonance region. The isobaric analog excitation functions rise more steeply than the continuum single-charge-exchange cross sections.