An empirical formula for L line X-ray production cross-section of elements from Ag to U for protons below 3.5 MeV

When computing element concentration from proton induced X-ray emission analysis, an important parameter is the X-ray production cross-section. There have been numerous experimental and theoretical works in this field. Nonetheless, although there is a simple analytical formula to compute K X-ray cross-sections, there is no such ones for the L lines. We present here analytical formulas for the cross-section of the three main X-ray lines L-alpha L-beta and L-gamma based on experimental data. So far, nearly 3000 values of cross-sections for elements from Ag to U and proton energy ranging from 0.5 to 3.5 MeV have been collected from various references. This experimental data set has been fitted for each Xray line with an exponential function depending on the proton energy and on the element atomic number. These fitted values have then been compared to the experimental data and with theoretical values obtained by the ECPSSR theory and Coster-Kronig fluorescence yields. (C) 2002 Elsevier Science B.V. All rights reserved.