Pion production in heavy ion reactions induced by16O and84Kr beams at 60 MeV per nucleon

Low energyπ+ andπ− production cross sections have been measured in16O at 65 MeV/u and84Kr at 60 MeV/u induced reactions on7Li,12C,27Al,108Ag and197Au. The results are compared with a previous measurement obtained with16O at 93 MeV/u. Large deviations are observed between light and heavy ion data. At variance with16O, the ratiosπ−/π+ are independent of the target in the Krypton case. A change in the regime of the projectile-target mass scaling of cross-sections is observed with the heaviest projectile.