Measurement of Charged-Pion Production by 7.28-GeV Nitrogen Ions

Cross sections for charged-pi-meson production by 7.28-GeV nitrogen ions on elemental targets were measured at a laboratory angle of 15° at the Princeton Particle Accelerator. At pion energies of ∼ 260 and ∼ 415 MeV, the data show the $A^{\frac{1}{3}}$ dependence predicted by an "effective number of nucleons" model. For ${\pi }^{-}$ energies above ∼ 415 MeV, the measured cross sections exceed those calculated from nucleon-nucleus data, even after the inclusion of Fermi-motion effects.