The elastic scattering of intermediate energy pions from ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and the single charge exchange scattering from ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ are calculated with a theoretical momentum space optical potential including spin, nucleon recoil, Fermi motion and binding, and a Lorentz invariant angle transformation. Realistic nuclear form factors and a $\pi N T$ matrix with a finite range are employed. An examination is made of the $\pi$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and $\pi$-${}_{}{}^3{}_{}{}^{}\mathrm{He}$ total and differential cross section data of several experimental groups and the possibility of extracting information on the magnetic moment form factor of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is investigated. Comparisons are made with the procedures and results of several theoretical groups to determine the relevant physical differences and the areas in need of improvement.

NUCLEAR REACTIONS ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(${\pi }^{\pm },{\pi }^{\pm }$), ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(${\pi }^{\pm },{\pi }^{\pm }$) elastic, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(${\pi }^{-},{\pi }^0$) ${}_{}{}^3{}_{}{}^{}\mathrm{He}$; $E=100-260\mathrm{}$ MeV; $\sigma \left(\theta \right)$ and ${\sigma }_{\mathrm{TOT}}$; theoretical calculation, momentum space optical potential; binding, recoil, Fermi motion, angle transformation; compare data and other calculations.

• Received 9 September 1976

DOI:https://doi.org/10.1103/PhysRevC.15.2127