PION SHADOWING AS A TOOL TO STUDY THE TOPOLOGY OF HEAVY-ION COLLISIONS AT INTERMEDIATE ENERGIES

The pion reabsorption effect has been exploited, through a new analysi s technique, to study the topological distribution of nuclear matter i n the course of a heavy-ion collision at intermediate energies. The az imuthal angular distribution of pions with respect to the reaction pla ne and the angular correlations between pions and projectilelike fragm ents have been investigated. Quantitative estimations of the pion prod uction time scale and of the impact parameter range involved an provid ed. The experimental results are successfully compared with the predic tions of a microscopic theoretical model based on the solution of the Boltzmann-Nordheim-Vlasov transport equation.