Search

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 3.4 the average multiplicity is nearly independent of the size (ν) of the target nucleus, while it increases for 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.

Coherent 3\piproduction on nine different nuclear targets has been studied using a 40 GeV/c\pi^{-} beam at Serpukhov accelerator. Absorption in nuclear matter of the produced system has been measured by analysing the data on the different nuclear targets. Identical results are obtained from the differential cross sections and from the coherent nuclear cross sections. The 1^{+} waves show a very weak absorption, definitely smaller than 0^{-} and 2^{-} waves. No influence on the absorption comes from the spin-flip amplitudes, which have been found to be negligible in the coherent region.