Small-Angle Pion Flux Produced in a Thick Beryllium Target by High-Energy Electrons

The pion yield produced by 16-GeV electrons in a 0.6-radiation-length beryllium target was studied at laboratory angles of 0.2° to 1.1°. The experimental yields are somewhat larger than those estimated using the Drell and $\rho$-diffraction models for pion photoproduction, and they do not appear to decrease at small angles as expected from the theoretical models.