Interference effects in pion double charge exchange

Abstract

Pion double charge exchange (${\ensuremath{\pi}}^{+}$,${\ensuremath{\pi}}^{\ensuremath{-}}$) has been measured using targets of $^{16}\mathrm{O}$ and $^{18}\mathrm{O}$ from 80 to 292 MeV at a laboratory angle of 5\ifmmode^\circ\else\textdegree\fi{}. 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 $^{16}\mathrm{O}$(${\ensuremath{\pi}}^{+}$,${\ensuremath{\pi}}^{\ensuremath{-}}$)$^{16}\mathrm{Ne}$(g.s.) and $^{18}\mathrm{O}$(${\ensuremath{\pi}}^{+}$,${\ensuremath{\pi}}^{\ensuremath{-}}$)$^{18}\mathrm{Ne}$(g.s.); $\ensuremath{\theta}=5\ifmmode^\circ\else\textdegree\fi{}$, ${E}_{\ensuremath{\pi}}=80 \mathrm{to} 292$ MeV, deduced two amplitude explanation for cross-section variation.