Saturation in the K-shell excitation of 120 MeV S14+ ions in interaction with gas targets

In contrast to the first Born approximation predicted quadratic enhancement , saturation has been observed in the excitation cross-sections of 120 MeV S14+ ions in interaction with gas targets. The measured cross-sections agre e with the theoretical calculations in the framework of the Schwinger varia tional principle. The symmetric eikonal CDW approximation, however, underes timates the cross-sections with the heavier target atoms.