Inelastic pion scattering from 12C.

Differential cross sections for inelastic pion scattering from $^{12}\mathrm{C}$ at incident energies of 100 to 291 MeV and momentum transfers \ensuremath{\le}300 MeV/c have been measured and are compared to results obtained from other probes, particularly electrons and protons. Angular distributions and excitation functions are presented for many of the bound states, including the 4.44-MeV (${2}^{+}$,0), 7.66-MeV (${0}^{+}$,0), 9.64-MeV (${3}^{\mathrm{\ensuremath{-}}}$,0), 12.71-MeV/15.11-Mev (${1}^{+}$;0,1) doublet, 16.11-MeV (${2}^{+}$,1), 19-MeV (${4}^{\mathrm{\ensuremath{-}}}$;0,1) doublet, and ${2}^{\mathrm{\ensuremath{-}}}$ states at 18.25 and 19.4 MeV. Distorted-wave impulse-approximation calculations using both macroscopic and microscopic descriptions of the nuclear wave functions are compared to the data. The observation of an anomalous excitation function for the 15.11-MeV level and the observation of dramatic ${\ensuremath{\pi}}^{+}$/${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ asymmetries near 18 and 19 MeV excitation due to isospin mixing between ${2}^{\mathrm{\ensuremath{-}}}$ states and between members of the ${4}^{\mathrm{\ensuremath{-}}}$ doublet are of particular interest.