Rapidities of produced particles in 200-GeV/cπ+/p/K+interactions on Au, Ag, and Mg

We have used the Fermilab 30-in. bubble chamber–hybrid spectrometer to study the rapidities of ‘‘produced particles’’ in the interactions of 200-GeV/c protons and ${\pi }^{+}$ and $K^{+}$ mesons with nuclei of gold, silver, and magnesium. The average rapidity decreases linearly with the number of projectile collisions ${\nu }_p$ (up to ${\nu }_p$=5) with no A dependence and little beam dependence. The ratio R of normalized rapidity distributions for hadron-nucleus to hadron-proton interactions shows a plateau in the central region, and becomes much larger in the target region. However, the increase is significantly less than has been reported in previous experiments. As a function of ${\nu }_p$, the ratio R rises linearly in the target region, more gently in the central region, and decreases slowly in the projectile region, in all cases with no A dependence. Some discrepancies with a previous experiment are observed in the central region. Long-range rapidity correlations are observed in hadron-nucleus events, but not in hadron-proton events. For the former, it is shown that the correlations exist only for those events with multiple projectile collisions, as expected in the multichain dual parton model.