Low energy pion-nucleus potentials from differential and integral data

Total reaction cross sections were measured for 50 MeV π^± on Si and Ni, 65 MeV π^± on Ni, and 80 MeV π^± on C, Ca, Zr, and Pb. Together with similar data measured previously for 50 and 65 MeV π^± on several targets, these cross sections were used as constraints in optical-model analysis of the elastic scattering of pions by nuclei. Also analyzing data at 20 and 30 MeV, a pion-nucleus potential was constructed that is strongly linked with the free pion-nucleon interaction, has smooth variation with energy between 0 and 80 MeV, and is capable of describing very well, much better than any potential published so far, all available data on differential and integral cross sections for π⁺ and π^- interactions with nuclei.