New experimental results for particle production from nuclei

Particle production from nuclei was studied for π,p and p-bar interactions at 20 to 150 GeV/c at the CERN SPS. The detector distinguishes between fast and slow particles, mainly pions and recoil protons, respectively, with a cut at a velocity v = 0.7c. Angular distributions, multiplicity distributions, and correlations were analysed. The pseudorapidity distributions of fast particles, normalized to one collision, depend only very weakly on the incoming energy and scale well with = Asigma/sub hN//sigma/sub hA/. This novel result is in contradiction with most of the models proposed so far. Conclusions are drawn for those models which describe hadron-nucleus collisions in terms of multiple soft quark interactions. As a function of the number of observed recoil protons, the multiplicity distriubtions of fast particles do not obey KNO scaling. We examine whether this result is consistent with the predictions of the coherent tube model. Finally, correlations in phase space of slow and fast particles are discussed and an outlook is given for future experiments