Charged-particle multiplicity in $pi$$sup -$-nucleus interactions at 100 and 175 GeV/c

The space-time evolution of particle production at high energies was investigated by measuring the charged multiplicity in ${\ensuremath{\pi}}^{\ensuremath{-}}$-nucleus collisions at 100 and 175 GeV/c. We find that (a) the forward multiplicity (in the $\ensuremath{\pi}p$ center-of-mass system) is independent of the target nucleus; (b) the backward multiplicity is approximately proportional to the nuclear thickness; and (c) the data are consistent with the assumption that the absorption cross section of the incident particle characterizes the multiplication process.