Isospin Dependence of Pion Absorption on a Pair of Nucleons

Abstract

The relative cross sections for the $2N+\pi \to 2N$ reactions were determined where the initial two nucleons are in a relative $s$ state, and coupled either to isospin zero or to one. This information is extracted from two-nucleon coincidence measurements of the (${\pi }^{+}$, $2p$) and the (${\pi }^{-}$, $\mathrm{pn}$) reactions on targets of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$.