Pion production excitation functions in proton-nucleus collisions from the absolute threshold to 500 MeV

Pion excitation functions in proton-nucleus collisions, from the absolute threshold to 500 MeV, have been measured with 1 MeV beam energy resolution at the CELSIUS storage ring, operating in slow ramping mode. Total yields, angular distributions, and target mass dependence of ${\pi }^{+}$ production are generally reproduced well by QMD calculations. The ${\pi }^{+}/{\pi }^{-}$ ratios are not reproduced equally well, obviously because the detailed description of the pion interaction with the Coulomb field is very delicate.