Pion-baryon correlations in nucleus-nucleus collisions between 400 and 800 MeV per nucleon

Triple differential cross sections of charged pions were measured for Ne projectiles at E/A = 600 and 400 MeV with NaF, Nb, and Pb Targets, and for Ar projectiles at E/A = 600 and 400 MeV with Ca, Nb, Pb Targets. The reaction plane was determined event by event from the light-baryon momenta distribution. For asymmetrical systems (AT>Ap), preferential emission of charged pions away from the interaction zone towards the projectile side in the transverse direction was observed. Such a preferential emission, which is not predicted by cascade calculations, is interpreted as the consequence of a stronger pion absorption by the heavier spectator remnant. Invariant mass distributions of [p, π+] pairs emitted in Ne-NaF collisions at E/A=800 MeV and Ar+Ca at E/A=600 MeV have also been studied. After background subtraction by the so-called event mixing method, we extract a signal roughly centered on the delta mass. This signal decreases when the particle multiplicity increases