Measurement of charged-pion production by 7.28-GeV nitrogen ions

The differential cross sections for the production of charged π mesons by collisions between 7.28-GeV nitrogen nuclei and ten elemental targets at 3degree and 15degree were measured at the Princeton Particle Accelerator. The cross sections as a function of atomic weight of the target are consistent with the A/sup 1/3/ dependence expected if the reaction is localized on the nuclear surface, and with the predictions of an ''effective nucleon number'' model of production via the Δ (1236) isobar. For pion energies below about 415 MeV, the pion yield agrees well with values derived from proton-nucleus data and simple Fermi-motion calculations. Above about 415 MeV the measured cross section is higher than that calculated from nucleon-nucleus cross sections, even after Fermi-motion effects have been taken into account