Pion double charge exchange (${\pi }^{+}$,${\pi }^{-}$) has been measured using targets of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ from 80 to 292 MeV at a laboratory angle of 5°. The magnitude and energy dependence of the cross section for the double-analog transition is qualitatively described in terms of a direct double-analog amplitude and a two-step nonanalog amplitude.

NUCLEAR REACTIONS ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${\pi }^{+}$,${\pi }^{-}$)${}_{}{}^{16}{}_{}{}^{}\mathrm{Ne}$(g.s.) and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$(${\pi }^{+}$,${\pi }^{-}$)${}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$(g.s.); $\theta =5\mathrm{}°$, $E_{\pi }=80\mathrm{} \mathrm{to} 292$ MeV, deduced two amplitude explanation for cross-section variation.

• Received 13 January 1981

DOI:https://doi.org/10.1103/PhysRevC.25.924