Forward baryons in relativistic nucleus-nucleus collisions

Abstract

We present the rapidity and transverse momentum distributions of protons and neutrons from collisions between 14.6 GeV/nucleon beams of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and targets of Al, Cu, and Pb. The data were measured in the forward spectrometer/target calorimeter detectors of the E814 apparatus. The results indicate the existence of two distinct domains, one of beam rapidity projectilelike nucleons, and the second of participant nucleons. From the former, the in-medium inelastic nucleon-nucleon cross section is deduced. It is found to agree, within 10%, with the ‘‘free’’ value of 30 mb although under present conditions one of the two colliding nucleons has been struck before with a high probability. We compare with the present data the predictions of a fragmentation model as well as of models dealing explicitly with the heavy-ion collision and particle creation and emission.