Pion production in nucleus-nucleus collisions at intermediate energies

Pion production is an important reaction channel in nucleus-nucleus collisions at bombarding energies above 500 MeV/n. The inelastic nucleon-nucleon cross section is dominated by pion production, which therefore is a key mechanism for the understanding of the dynamics of a nucleus-nucleus collision and of the behaviour of nuclear matter under extreme conditions. Some of the important features of pion production in nucleus-nucleus collisions at intermediate energies are discussed. A selection of pion data measured in the last two decades from the pioneering experiments at LBL up to the recent measurements at GSI are presented. (K.A.). 34 refs., 13 figs