Pion nucleus total cross sections from 86 to 860 MeV.

A description is given of the measurement of pion nucleus total cross sections at 14 energies between 90 and 860 MeV for [6]Li, [7]Li, [9]Be, [12]C, and 6 energies between 88 and 228 MeV for [16]O. The measurements have been made with both positive and negative pions. The results have been used to calculate values for the real part of the forward scattering amplitude and for an effective pion nucleus coupling constant, using the method of forward dispersion relations. Calculations of the total cross sections have also been done with various forms of optical model, including the Laplacian and Kisslinger models and the results compared with the data, and the effect of more recently proposed modifications to these optical models has been investigated. A semi-classical model has been used to estimate the effect of the distortion of the pion wave due to the Coulomb field. The results have been compared with optical model calculations and the data