Investigation of pion absorption in heavy-ion induced subthreshold π 0 production

We present results from an experimental study of reabsorption effects in subthreshold pi0 production in the reaction Xe-129 + Au-197 at 44 MeV/nucleon. Within the picture of pion generation in nucleon-nucleon scattering we deduce, from our data and from a comparison with the systematics of production cross sections available for lighter reaction systems, information on the pi0 absorption length in nuclear matter. For the pi0 kinetic-energy range congruent-to 5-100 MeV the energy-averaged lambda(abs) and its momentum dependence are obtained, and compared with optical-model calculations.