ETA-MESON PRODUCTION AND DELTA-RESONANCE EXCITATION IN HEAVY-ION COLLISIONS BELOW THE PION THRESHOLD

We measured eta and pi(0) meson production in nucleus-nucleus reaction at beam energy below the free nucleon-nucleon pion creation threshold . Preliminary resuts indicate that the scaling on the transverse mass between pi's and eta's is still valid at very low energies. Meson cros s sections can be understood in terms of thermal population of the bar yonic resonances Delta(1232) and N(1535). Also, we observe a statisti cally-significant correlation for proton-pi(0) coincidencies, which we assign to the strength distribution of the Delta baryonic resonance. The same analysis shows no correlation in the case of deuteron-pi(0) c oincidencies.