Threshold pion production and multiplicity in heavy-ion collisions

Charged pions emerge from roughly 70% of the neon interactions that produce stars in nuclear emulsions at incident energies between 100 and 280 MeV/nucleon. The charged-pion multiplicity averaged 2.8 per pion-producing event. The data are in apparent disagreement with predictions based upon the independent-particle model. Agreement is found with the pion-condensation model of high-density nuclear states as formulated by Kitazoe et al