Coulomb effects in charged particle spectra from heavy ion collisions at AGS and SIS

Data from the AGS experiment E866 on charged particles emitted in central A u+Au collisions at 10.8 AGeV incident energy is reviewed. The study of spec tral shapes indicates the presence of collective transverse flow and - in p articular for charged pions - of Coulomb final state interaction between em itted particles and the nuclear charge distribution. The comparison to SIS pion data measured with KaoS elucidates the role of charged pions to probe nuclear reaction dynamics at lower incident energies.