Pion-induced double charge exchange onO18

The reaction ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}({\pi }^{+}, {\pi }^{-})$ ${}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$(g.s.) is calculated using the optical model, including coupling through the 0+, 2+, and 4+ states in ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$. In addition to the analog, the 2+ and 4+ intermediate states are found to be quite important between 100 and 200 MeV. Good agreement is obtained with the experimental cross sections at 0°.