PION KAON AND ANTIPROTON PRODUCTION IN CENTER-OF-MASS IN HIGH-ENERGY PROTON-PROTON COLLISIONS

The differential production cross section d2σdΩdP has been measured for pions, kaons, and antiprotons produced in 12.5-GeV/c proton-proton collisions. In this experiment we studied the dependence of d2σdΩdP on the longitudinal and transverse components of the c.m. momenta of the produced particles, Pl and P, while holding all other variables fixed in the center-of-mass system. The ranges of the components measured were Pl=0.0-1.0 GeV/c and P2=0.1-1.5 (GeV/c)2. The 12.5-GeV/c extracted proton beam of the Argonne ZGS impinged upon a liquid-hydrogen target. The produced particles were detected by a spectrometer containing two bending magnets and erenkov counters and scintillation counters in coincidence. The incident proton flux was determined by monitor scintillators calibrated during gold-foil irradiations. The cross sections for the production of π± and K± were all found to have an unambiguous Gaussian dependence on P over the entire range. In the formula d2σdΩdP=Bexp(-AP2), we found A3.5 (GeV/c)-2 for π± and K-. However, for K+ we found A2.7 (GeV/c)-2. In studying the dependence of d2σdΩdP on Pl, we found that the cross section was very strongly peaked about Pl0.5 GeV/c, with very few particles produced near Pl=0. This shows that there is no tendency for particles to be produced at rest in the center-of-mass system. (Such production is predicted by the statistical model.) Instead, particles come out in two clouds or fireballs" following the two departing baryons. These fireballs have a mass of about 2100 MeV. © 1968 The American Physical Society."