ReactionsHe3(π−, n)H2andHe4(π−, n)H3at Pion Energies of 100, 200, and 290 MeV

Differential cross sections for the (${\pi }^{-}, n$) reactions in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ have been measured at energies of 100, 200, and 290 MeV. The angular distributions for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ are different, with ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ characterized by an oscillatory pattern with a dip at a fixed angle of ≃ 70°. The forward-angle cross sections show a simple dependence upon momentum transfer for both ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. These results are discussed in the context of single-nucleon and multinucleon reaction diagrams.