Quasielastic scattering of pions fromC12andCa40,44,48

Measurements have been made of the differential cross section $\frac{d^2\sigma }{d\Omega \mathrm{dE}}$ for the scattering of ${\pi }^{\pm }$ from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{40,44,48}{}_{}{}^{}\mathrm{Ca}$ in the energy region corresponding to quasielastic scattering. Data were taken at incident energies and laboratory angles of 180 MeV, 60°, and 290 MeV, 60° and 120°. The results are compared to a free pion-nucleon cross-section model and to a model based on pion scattering from a Fermi gas of nucleons, which incorporates free pion-nucleon cross sections. Monte Carlo methods were used for the second model, and both single scattering and multiple scattering were allowed. Several qualitative features of the data are explained by the multiple scattering calculation, but not by the free cross-section model or the single scattering model.