Strange Baryon Production and Projectile Fragmentation in p–A Collisions at the AGS

Abstract

Experiment 910 (E910) has studied proton-nucleus collisions at 12.3 and 17.5 GeV incident energies using a variety of targets. Centrality selection is provided via “grey” track multiplicity which can be statistically related to ν, the number of scatterings of the proton in the target nucleus. Previously published semi-inclusive measurements of Ν production are discussed and preliminary measurements of “leading” Ν production in 17.5 GeV p-Au collisions are presented as a function of ν. The data indicate that the probability for the projectile to fragment into a strange baryon increases significantly with increasing ν for ν≤3; an extrapolation of the E910 data to nucleus-nucleus collisions can reproduce most of the enhancement in Ν production observed in Pb-Pb collisions at 40, 80 and 160 A. GeV. Preliminary measurements of Ξ− production in 17.5 GeV p-Au collisions show a rapid increase in yield with increasing ν. The data are discussed in the context of the Van Hove fragmentation model. Preliminary proton and pion spectra are presented for 12.3 GeV p-Be collisions. The data show a rapid degradation of outgoing proton momenta with increasing N grey while only modest changes are observed in the pion fragmentation spectra.