Negative Pion Production from Neutrons by PolarizedγRays

The differential asymmetry ratio for the process $\gamma +n\to p+{\pi }^{-}$ was measured at 90° in the center-of-mass system and for incident photon energies from 352 to 550 MeV. The observed asymmetries are larger than the values predicted from the theory by Berends, Donnachie, and Weaver. A smaller $M_1$- amplitude gives better agreement between the experiment and the theory.