Direct observation of systematic deviations from the Bethe stopping theory for relativistic heavy ions

The SIS accelerator facilities at GSI in combination with a magnetic spectrometer allow the direct measurement of stopping powers for relativistic heavy ions up to uranium with high precision for the first time. Here, we report our representative results obtained for projectiles up to xenon in the energy range from 700 to 1000 MeV/u. Systematic deviations from the Bethe stopping-power theory are observed, whereas the data are in good agreement with theory once Mott and Bloch corrections and the Fermi density effect are included.