MULTIPLICITY OF CHARGED-PARTICLES IN PI-INTERACTIONS ON NUCLEI AT 40-GEV-C

Multiparticle production in π--nucleus interactions at 40 GeV/c (Fifth Joint CERN-Serpukhov Experiment) has been studied using a spark-chamber technique at the Serpukhov accelerator. The mean multiplicities, the pseudorapidity distributions and the dispersion of the multiplicity distributions of charged particles produced on C, Al, Cu and Pb targets are presented. The data have been analysed, both subtracting and including secondary protons with p < 1 GeV/c. In the region of pseudorapidity η > 3.4 the average multiplicity is nearly independent of the size (ν) of the target nucleus, while it increases for η < 3.4. In the forward direction (η > 4) the mean multiplicity on nuclei is smaller than the mean multiplicity on hydrogen. The dependence upon ν in the target fragmentation region is stronger when the emitted protons are included in the pseudorapidity distributions of the secondary particles. The dispersion of the multiplicity distributions for the different nuclear targets versus the mean multiplicity shows the same slope as found by the world statistics on hydrogen and by other experiments on nuclei at different energies. The results are compared with the predictions of the coherent tube model and with the soft hadron-nucleus collision model. © 1979.