Monte Carlo simulations of disturbing effects in quantitative in-situ X-ray fluorescence analysis and microanalysis

This paper deals with difficulties in making a quantitative evaluation with the use of in-situ X-ray fluorescence analysis. Incorrect sample positioning and some properties of the surface of the sample have a negative effect on quantitative analyses. Monte Carlo simulations with the MCNPX code were used for classifying the disturbing effects that must be taken into account in-situ X-ray fluorescence analysis. The relation between the count rate and variations in the geometrical arrangement has been studied. The Monte Carlo calculations provide an interpretation of effects that had been ascertained experimentally and also imply the range of uncertainties in the count rates. The results enable us to find an optimal set-up for a given in-situ measurement.