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MATHEMATICAL TECHNIQUES FOR X-RAY ANALYZERS
Citation:
Gardner, R. AND K. Verghese. MATHEMATICAL TECHNIQUES FOR X-RAY ANALYZERS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-80/070.
Description:
Mathematical techniques and subsequent computer software were developed to process energy-dispersive x-ray fluorescence spectra for elemental analysis of airborne particulate matter collected on filters. The research concerned two areas: (1) determination of characteristic x-ray intensities and (2) determination of elemental amounts from the known characteristic x-ray intensities. In the first area, efforts primarily concentrated on developing and implementating of the library, linear least-squares method and included the two common non-linear aspects of XRF pulse-height spectra: excitation source background and pulse pile up. A detector response function model was also developed for si(Li) detectors to alleviate the necessity for obtaining and storing extensive complete library spectra for every element of interest. This approach gives improved accuracy, greatly reduces the experimental effort required, and is capable of accounting for variations in detector calibration and resolution without requiring extensive additional experimental effort. In the second research area the fundamental parameters method was developed by Monte Carlo simulation. Data were collected for several shapes of particles deposited on filters. Empirical correction factors for various practical cases of interest based on these simulations are reported.