L-SHELL X-RAY-PRODUCTION BY 2-12-MEV CARBON-IONS IN 15 SELECTED ELEMENTS FROM COPPER TO LEAD

L-shell x-ray production cross sections for (29)Cur Ga-31, Ge-32, Br-3 5, Y-39, Mo-42, Ag-47, Sn-50, La-57, Nd-60, Gd-64, Ho-67, Yb-70, Au-79 and Pb-82 were measured for carbon ions in the 2-12 MeV energy range. The copper to yttrium data were previously measured using a Si(Li) de tector with a beryllium window, while the molybdenum to lead x-rays we re counted with a windowless Si(Li) detector, whose efficiency was det ermined by various normalization techniques. The measured x-ray cross sections are compared to predicted x-ray cross sections from the first Born and the ECPSSR theories. Using single-hole fluorescence yields, at low projectile velocities the first Born approximation overpredicts the data by as much as one order of magnitude while the ECPSSR theory at worse underestimates the data by about a factor of four. For the h ighest projectile velocities relative to target L-shell electrons, bot h theories converge toward the data to almost within experimental unce rtainties. After modifying the fluorescence yield to account for multi ple outer-shell ionization, the ECPSSR theory is brought into better a greement with the data for light targets but still overestimates the d ata for heavier targets. Also, the 2 MeV measurements using doubly ion ized carbon ions are still significantly underestimated by the ECPSSR theory even after accounting for multiple ionization. Our multiple ion ization correction assumes that the target foil thickness is thin enou gh to insure single collision conditions. However, in order to obtain acceptable signal-to-noise ratios, the target foils used in this exper iment were too thick to provide single collision conditions. For thick er foils, ions are stripped inside the target resulting in an apprecia ble fraction of higher charge states that enhance the ionization of ou ter shells and the effective fluorescence yields. This effect could ac count for the remaining discrepancy between the ECPSSR theory and the data.