The capabilities of an electrically cooled energy-dispersive x-ray detector for quantitative x-ray fluorescence analysis

摘要

The capabilities of the Si PIN diode x-ray detector were determined and compared with those of a standard Si(Li) detector. The x-ray fluorescence (XRF) analysis systems assembled with these two detectors included annular radioisotope excitation sources of Cd-109 and Fe-55. The systems were calibrated for sensitivity and quantification was performed with fundamental parameters software. Based on the analysis of the standard reference material NIST 2710 (Montana soil), the elemental sensitivities and the limits of detection of both systems were obtained. The elemental sensitivities of the Si PIN detector for fluorescence x-rays in the energy range up to 10 keV were comparable to those of the Si(Li) detector. At higher fluorescence x-ray energies the sensitivity of the Si PIN detector gradually decreased and was smaller by a factor of similar to4 at 20 keV. The reason was mainly the small thickness of the sensitive volume of the Si PIN diode (0.2 mm) and therefore the smaller relative efficiency of this detector. The assessed limits of detection (LODs) were comparable for the two detectors, which was mainly due to the lower spectral background of the Si PIN detector in excitation with the Cd-109 source as a result of its smaller sensitive thickness. The accuracy of elemental determinations for the two detectors was comparable and within the limits of the assessed uncertainties, which were calculated considering all the steps of the analysis, i.e. spectrum measurement and analysis, sensitivity calibration and quantification. Copyright (C) 2004 John Wiley Sons, Ltd.