XRF Systems Research Articles

Applicability of annular‐source excited systems in quantitative XRF analysis

AbstractRadioisotope‐excited XRF systems, using annular sources, are widely used in view of their simplicity, wide availability, relatively low price for the complete system and good overall performance with respect to accuracy and detection limits. However, some problems arise when the use of fundamental‐parameter techniques for quantitative analysis is attempted. These problems are due to the fact that the systems operate with large solid angles for incoming and emerging radiation, and both the incident and take‐off angles are not trivial. In this paper, an improved way to calculate ‘effective’ values for the incident and take‐off angles, using Monte Carlo (MC) integration techniques, is shown. In addition, a study of the applicability of the ‘;effective’ angles for analysing different samples, or standards, was carried out. The MC method allows also calculation of the excitation‐detection efficiency for different parts of the sample and estimation of the overall efficiency of a source‐excited XRF set‐up. The former information is useful in the design of optimized XRF set‐ups and prediction of the response of inhomogeneous samples. A study of the sensitivity of the results due to sample characteristics and a comparison of the results with experimentally determined values for incident and take‐off angles is also presented. A flexible and user‐friendly computer program was developed in order to perform efficiently the lengthy calculations involved.

Application of Fundamental Parameter Software to On-Line XRF Analysis

X-ray fluorescence analysis (XRF) is an analytical method which has been adapted with considerable success to on-line industrial process analysis with various degrees of sophistication. Process analysis XRF systems range from relatively simple units utilizing radioisotope sources with non-dispersive analyzers to complex wavelength dispersive systems in a central location receiving samples from a number of process streams. The advantages of on-line process analytical instrumentation for quality control, regulatory 2 compliance and safety considerations are well documented. ' Advances in the development of low maintenance thermoelectrically cooled Si(Li) detectors have made energy dispersive X-ray fluorescence analysis (EDXRF) even more amendable to on-line process analysis. EDXRF is an important method of on-line instrumentation because of its ability to simultaneously detect many elements.

Radioisotope-induced xrf analysis of tumor-frelated tissue samples

Healthy and tumor-bearing mice have been analyzed in a trace element time dependent study by employing two different radioisotope XRF systems. Results from these analytical systems, using a point and an annular sosurce, can be readily compared utilizing healthy tissue samples as the normalizing standard. Normalized elemental ratios generated with the two systems for similar tissue samples are in good agreement. The results reported use two of the points generated in the time study of the disease progresss, days zero and day 21.

X-Ray Tube Improvements for Better Performance in an Energy-Dispersive X-Ray Spectrometer System

AbstractImprovements in x-ray tube technology for the low-power tubes used in energy-dispersive XRF systems can provide better performance. These improvements are occurring in six areas: thin-window tubes, lower kV capability, higher kV and mA capability, pulsed tubes, smaller focal spots, and miniaturization. These improvements will lead to better excitation of the light elements, analysis of low-mass samples, higher count rates, small spot analysis, and smaller systems.

Verification of Stability and Precision for Energy-Dispersive XRF Systems

Instrument specifications as published by manufacturers generally include values for stability of various parameters or components. For an X-ray fluorescence system, a typical example might be the generator high voltage stability (perhaps 0.01%). Parameters of this sort are of course of some use in comparing systems, and they may be (and often are) of great importance to the manufacturer as a criterion of manufacturing quality. It is difficult for the user to know how any single one, or combination of these factors really affect the total system performance as it may relate to his application.