Inelastic High-Energy Proton-Proton Collisions

Abstract

We have measured the differential production cross section $\frac{{d}^{2}\ensuremath{\sigma}}{d\ensuremath{\Omega}\mathrm{dp}}$ for pions, kaons, protons, and antiprotons produced in $12.4\ensuremath{-}12.5\ensuremath{-}\frac{\mathrm{GeV}}{c}$ proton-proton collisions. We systematically studied the dependence of these cross sections on the center-of-mass longitudinal and transverse momentum of $\ensuremath{\pi}$'s, $K$'s, and $\overline{p}$'s, and on ${p}_{\mathrm{c}.\mathrm{m}.}$ and ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}$ for protons, over much of the available phase space. The extracted proton beam of the Argonne zero-gradient synchrotron (ZGS) impinged on a liquid-hydrogen target. The scattered particles were detected by a spectrometer using magnets and scintillation and Cherenkov counters to identify and momentum-analyze these particles. A steering magnet allowed detection of particles produced at different laboratory angles without moving any of the apparatus. The incident proton intensity was determined by monitor counters calibrated using foil spallation techniques. The pion production cross section was well represented by a sum of two Gaussians in ${{p}_{\ensuremath{\perp}}}^{2}:\frac{{d}^{2}\ensuremath{\sigma}}{d\ensuremath{\Omega}\mathrm{dp}}=A{e}^{\ensuremath{-}15{{p}_{\ensuremath{\perp}}}^{2}}+B{e}^{\ensuremath{-}3{{p}_{\ensuremath{\perp}}}^{2}}$. The slope for large-momentum-transfer kaon production was also about 3 ${(\frac{\mathrm{GeV}}{c})}^{\ensuremath{-}2}$. The pion production cross section as a function of ${p}_{l}^{{}^{\mathrm{c}.\mathrm{m}.}}$ had a maximum at ${p}_{l}^{{}^{\mathrm{c}.\mathrm{m}.}}=0$, possibly supporting a one-center model. Incorrect earlier measurements supporting a two-center model are discussed and corrected. The inelastic scattering cross section for protons also shows a less prominent forward peak and an ${e}^{\ensuremath{-}3{{p}_{\ensuremath{\perp}}}^{2}}$ dependence. This proton cross section also seems independent of inelasticity over a large range.