Pion production experiments with slowly ramped beams at storage rings

Slow ramping of magnets at the CELSIUS storage ring has been utilized to measure yields of charged pions in proton and heavy ion induced collisions with continuously varying beam energy. The data have been compared to BUU and QMD calculations which follow the general shape of the excitation functions quite well except very close to the absolute threshold. The search for narrow resonances is discussed. (orig.)