Pion production cross sections in heavy ion-induced reactions at energies close to the absolute threshold are calculated using a generalized version of the compound nucleus model of Aichelin and Bertsch. The calculated results are consistent with the data for laboratory energies per nucleon in excess of 50 MeV. For lower beam energies and for high pion kinetic energies, the model tends to underpredict the data. This indicates the presence of a nonstatistical component in the pion production process.

• Received 8 November 1985

DOI:https://doi.org/10.1103/PhysRevC.33.937