A second X-ray production database is introduced into GUPIX to complement t
he existing theoretical (ECPSSR-DHS) database and to provide some estimate
of analytical uncertainty due to this aspect of GUPIX; it is based on publi
shed compilations and analyses of large numbers of measured K and L subshel
l X-ray production cross-sections. The two databases are compared through a
nalysis of single-element standards and standard reference materials. Good
agreement is observed for the case of K X-rays. In contrast, neither the th
eoretical nor the "reference" database appears to be entirely satisfactory
in the case of L X-rays. New work is required on L subshell X-ray productio
n cross-sections using protons. The tools in GUPIX for film thickness deter
mination are expanded, and tested using the two alternative databases. (C)
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