Evidence for a Direct Three-Nucleon Pion-Absorption Process

Abstract

Evidence for a three-nucleon absorption mechanism has been observed in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ for positive and negative pions of 220 MeV/c. The effect shows pure phase-space behavior with integrated cross sections of 3.9±0.5 mb for ${\pi }^{+}$ and 3.7±0.6 mb for ${\pi }^{-}$ absorption.