The angular distribution and the excitation function of the reaction ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}({\pi }^{+}, {\pi }^{-}){}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ (double isobaric analog state) can be well understood in the framework of a coupled-channel diffractive scattering theory provided we include higher-order processes. Use of a scaling theory allows an essentially parameter-free calculation of these processes and makes possible the study of effects arising from finer aspects of nuclear structure such as the core excitation of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$.

NUCLEAR REACTIONS ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}({\pi }^{+}, {\pi }^{-}){}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ (DIAS) at $T_{\pi }=50-300\mathrm{}$ MeV; excitation functions; elastic and double-charge-exchange differential cross sections; effects of two-nucleon processes and nuclear structure.

• Received 10 December 1981

DOI:https://doi.org/10.1103/PhysRevC.27.1611