A phenomenological investigation of the shower particle pseudorapidity fluctuations in hadron-nucleus collisions

Abstract

From the experimental matrix ƒ(N g ; n s , Δη i) (the number of events with a given number N g of particles with velocity 0.3 c< v<0.7 c, and n s, the number of shower particles ( v > 0.7 c) in a pseudo-rapidity interval Δη i ) obtained from the Heidelberg-Igel hadron-nucleus experiment at CERN, we extract the shower particle multiplicity distributions as a function of ν, the number of nucleons that interacted with the projectile. We use a theoretically justified statistical correlation between ν and N g (recoil protons) and the assumption that the correlation between n s and N g is given merely through ν. The data used are for incoming energies 50 and 150 GeV with a proton or pion as the projectile and Cu or Pb as the target. We find that the shower particle multiplicity distributions are of a Poissonian character in each η bin and for each value of ν. The average multiplicities 〈n s 〉(ν) Δη i are approximately the same for the two targets and for the different projectile, possibly with a small excess for the pion projectile. The results are compared to a rather general theoretical model of the soft interaction type. The predictions from this model for the shower particle pseudorapidity distributions are very close to the derived values.