Measurement of the average transverse momentum and of the pion-emission volume in proton-nucleus and antiproton-nucleus reactions at 200 GeV

We have measured as a function of multiplicity for the reaction proton (antiproton) on proton, neon, argon, and xenon. For all reactions, is independent of multiplicity. We observed that the pion-emission volume is the same for both hydrogen and xenon targets and has a radius about 1.5 fm. Our analysis shows no indication of a deconfinement phase transition in nuclear matter.