Search

Multiplicity distributions and two-particle correlation functions are presented for shower particles with pseudorapidity η>1 produced in π- interactions on C, Al, Cu, Pb targets at 40 GeV/c. The results are in the correlation function berween the data on nuclei and on hydrogen. The data are compared with the predictions of the additive quark model and the quasi-eikonal model.

The backward production of protons in the reaction π−A → p↓X is studied at 40 GeV incident energy with the different nuclear targets : C, Cu, Pb. The structure function shows a slope independent of the target atomic weightA and slightly dependent on the proton production angle. The invariant cross-section, normalized to the nucleon, increases withA up to a plateau which varies with the incident energy. Finally the ratiosR = (FA/A)/(FC/AC) andn = ln(FA/FC)/ln(A/AC), whereF = (E/p2)(d2σ/(dp dΩ)), show a flat dependence on the momentum of the proton backward produced. These results are in favour of few-nucleon correlation models.

The interaction length of a particle can be measured directly by studying the attenuat ion of a particle beam in a material. The number of particles which have not interacted after a depth z of absorber is given by .N(z) = .N0 exp [-z/k], .N o being the incoming flux. In an unseparated negative high-energy beam, pions predominate, and the number of particles which have not suffered an interaction is given by