L-SHELL X-RAY-PRODUCTION CROSS-SECTIONS IN FE-26, NI-28, CU-29, ZN-30, GA-31 AND GE-32 BY 0.5-MEV TO 8.0-MEV HE IONS

L-shell x-ray production cross sections by 0.5 to 5.0 MeV He+ and 5.5 to 8.0 MeV He2+ ions are reported for elements with x-rays between 0.7 0 keV and 1.19 keV. Thin targets of Fe-26, Ni-28, Cu-29, Zn-30, Ga-31 and Ge-32 were manufactured using a cleaning process that reduced the level of light element impurities. The x-rays were measured with a win dowless Si(Li) detector, whose efficiency was determined by the atomic -field bremsstrahlung method. The data are compared to the predictions of the first-order Born and the ECPSSR theories using the single- and multiple-hole fluorescence yields. The ECPSSR theory is clearly super ior to the first-order Born approximation, although the data fall-when single-hole fluorescence yields are used-on the average about 5% belo w the ECPSSR. At the lowest velocity, however, on the average this the ory underestimates our measurements by 15% when single-hole fluorescen ce yields are employed. When multiple-hole fluorescence yields are use d, the theory is within 3% of the averaged data at the lowest ion velo city. Coupled-state calculations that account for intrashell transitio ns and recently proposed modifications to the ECPSSR treatment of the binding effect give larger cross sections than the ECPSSR and hence-wh en multiple-hole fluorescence yields are used-they are in larger disag reement with our measurements. The measured cross sections are shown t o agree reasonably well with the results of our previous investigation s, except for very substantial discrepancies at the lowest ion energie s. We attribute these differences to systematic errors in our previous experiments due to the Be window of the Si(Li) detector that resulted in a particularly small signal-to-background ratio.