True absorption and scattering of 50 MeV pions

The inclusive pion inelastic scattering and true absorption cross sections at 50 MeV were measured for ${\pi }^{+}$ on natural Li, C, Fe, Nb, and Bi and for ${\pi }^{-}$ on C, Fe, and Bi. The results show that ${\pi }^{-}$ cross sections are much larger than ${\pi }^{+}$, the difference being significantly larger than expected from a simple Coulomb calculation. In particular, in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ the absorption of negative pions is about twice that of positive pions.