We have measured cross sections and analyzing powers for ${\mathrm{\pi }}^{+}$ and ${\mathrm{\pi }}^{\mathrm{-}}$ elastic scattering from a polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ target at ${\mathit{T}}_{\mathrm{\pi }}$=100 MeV. Measurements have been made over an angular range of 60° to 110° which extends over the region of the cross section minimum where spin effects in π-nucleus scattering are predicted to be largest. This is evident from the large value of ${\mathit{A}}_{\mathit{y}}$ observed in ${\mathrm{\pi }}^{+}$ scattering from ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ near ${\mathrm{\theta }}_{\mathrm{lab}}$=80°. The ${\mathit{A}}_{\mathit{y}}$ data for both ${\mathrm{\pi }}^{+}$ and ${\mathrm{\pi }}^{\mathrm{-}}$ scattering are qualitatively reproduced by a schematic PWIA model; however, agreement with the data is significantly improved when a full nonlocal DWIA reaction model employing realistic three-body wave functions is used. The asymmetry in ${\mathrm{\pi }}^{\mathrm{-}}$${\mathrm{-}}^3$He scattering resembles the asymmetry for ${\mathrm{\pi }}^{\mathrm{-}}$ scattering from a free neutron near the cross section minimum and is about half that for ${\mathrm{\pi }}^{+}$ scattering.

• Received 27 December 1993

DOI:https://doi.org/10.1103/PhysRevC.49.2045