Elastic pion Compton scattering

We present evidence for elastic pion Compton scattering as observed via the Primakoff process on nuclear targets. We find production cross sections for ${\pi }^{-}A\to {\pi }^{-}\gamma A$ on lead and copper of 0.249±0.027 and 0.029±0.006 mb, respectively, in agreement with the values expected from the one-photon-exchange mechanism of 0.268±0.018 and 0.035±0.004 mb in the region of our experimental acceptance. This reaction provides a clean test of the Primakoff formalism.