The Si(Li) X‐Ray energy analysis system: Operating principle and performance

Gedcke, D. A.

doi:10.1002/xrs.1300010403

Cited by 46 publications

(8 citation statements)

References 20 publications

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“…The Si(Li) detector consists of a small cylinder (about 1 cm diameter and 3 mm thick) of/?-type silicon that has been compensated by lithium to increase its electrical resistivity [6]. A Schottky barrier contact on the front of the silicon disk produces ap-i'-n type diode.…”

Section: The Si(li) Detectormentioning

confidence: 99%

Instrumentation for X‐Ray Spectrometry

Jenkins¹

1999

X‐Ray Fluorescence Spectrometry

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An X-ray spectrometer consists of five major portions:1. An excitation source. 2. A specimen presentation system. 3. A dispersing system. 4. A detection system. 5. A data collection and processing system. The excitation source is typically a high-powered X-ray tube driven by a high-voltage generator. The specimen presentation system is built in as an integral part of the spectrometer itself. In the case of wavelength dispersive spectrometers, the spectrometer has a means of setting angles (the goniometer) for selectable dispersing crystals. The detection system in wavelength dispersive systems is generally based on a pair of detectors mounted in a tandem configuration. In the case of energy dispersive spectrometers, a high-resolution, solid-state detector is used to fulfill both the dispersing and the detection requirements. In the case of modern spectrometers, based on either wavelength or energy dispersive principles, data collection and analysis systems are typically based on personal computers. EXCITATION OF X-RAYSSeveral different types of sources have been employed for the excitation of characteristic X-radiation and the most important of these are illustrated in Figure 6.1.As has been mentioned previously, all of the early work in X-ray spectrometry was done using electron excitation. This technique is still used very successfully today in electron column applications. Electron excitation is not frequently used in classical X-ray fluorescence systems, due mainly to the inconvenience of having to work under high vacuum and problems with 89 X-Ray Fluorescence Spectrometry, Second Edition

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Section: The Si(li) Detectormentioning

confidence: 99%

Instrumentation for X‐Ray Spectrometry

Jenkins¹

1999

X‐Ray Fluorescence Spectrometry

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“…The ratios should be constant and independent of the sample composition. Strictly speaking, Eqns (4) and (5) are not valid because the scattering cross-section as a function of atomic number and thus as a function of the sample composition is rather complicated. Scattering of the radiation striking the sample is performed over a variety of angles, due to the poor collimation of the of the exciting beam.…”

Section: Elmentioning

confidence: 99%

“…It could be derived from scattering experiments, with and without molybdenum filtration of the primary beam, that the contribution of the Bremsstrahlung spectrum amounts to less than 10% of the radiation continuum at any energy between 3 and 17 keV. (ii) The intensity ratio of K/3 t o K a or continuum to Ka measured after coherent and incoherent scattering, respectively [Eqns (4) and (5)] is nearly independent of the sample composition. The molybdenum loaded cellulose filters were measured and the results are summarized in Table 1.…”

Section: Verification Of the Assumptionsmentioning

confidence: 99%

Evaluation of a practical background calculation method in X‐ray energy analysis

Espen

Adams

1976

X-Ray Spectrometry

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Before investigating the applicability and the eventual causes of failure of the background correction using incoherent and coherent scatter peaks, it is necessary to examine in detail the different contributions to the XRF spectrum background.The background beneath the fluorescence lines of energy dispersive X-ray spectra obtained with a molybdenum secondary target tubeexcited system can be obtained from the intensities of the coherently and incoherently scattered radiation. The background intensity at a particular energy is equal to the product of a proportionality factor multiplied by the incoherently scattered radiation intensity, plus another proportionality factor multiplied by the coherently scattered radiation intensity. The proportionality factors are determined from measurements of a number of molybdenum-loaded cellulose filters.The proposed procedure provides accurate results for the analysis of complex X-ray spectra of thin samples of varying composition. TheoryWhen monoenergetic X-rays strike the detector, the spectrum consists of discontinuous features such as the full energy peak and the escape peak and a continuous spectral component. The latter consists of first, the

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“…Οι ενεργές διατομές παραγωγής των διαφόρων χαρακτηριστικών ακτινών χ απο πρωτόνια υπολογίζονται μέσω των σχέσεων (2.12). Πάχοε (mg/cm ) [133,134]. Τα βασικά πλεονεκτήματα που έχει το σύστημα ανίχνευσης Si(Li) είναι:…”

Section: βάση δεδομένων και εκτίμηση σφαλμάτων στους υ πολογισμούςunclassified

Παραγωγη Μονοχρωματικων Δεσμων Ακτινων Χ Απο Πρωτονια Και Χρηση Τους Σε Αναλυτικες Εφαρμογες

Καρυδασ¹

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The possibility of using protons with energy of a few MeV for the production of monoenergetic x-ray beams with application to the x-ray fluorescence analysis (XRF), was investigated theoretically and experi mentally. The yield of the characteristic x-rays, produced when a pure target is bombarded by protons, was calculated (at reflection or trans mission geometry) and its dependence on various experimental param eters (proton energy, angle of incidence) was studied. An experimen tal arrangement with small intercomponent diastances (source-sampledetector) and suitable for sample irradiation and detection of the fluo rescent x-rays in vacuum, was constructed. The background produced in the Si(Li) detector by the γ-rays, originating from the primary target, was studied as a function of the proton energy, for the purpose of finding an optimum energy. For calibration purposes, a number of thin targets were made and their thickness was measured employing independent methods. Also, in order to improve the accuracy of the calibration pro cedure, the exact theoretical calculation of the enhancement of the XRF intensity, due to the scattering inside the sample of either the exciting or the characteristic radiation, was performed. A software program for the quantitative analysis of homogeneous samples was developed, which take into account all second order corrections to the XRF intensity and also having the advantage of using simultaneously data from many x-ray sources. The concentrations of various elements contained in standard samples (biological, clays, steels) were measured with good agreement with the certified values. Also, the sensitivity of the method in the anal ysis of trace elements contained in biological samples was investigated with the final conclusion that minimum detection limits lower than 1 ppm can be achieved.

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The Si(Li) X‐Ray energy analysis system: Operating principle and performance

Cited by 46 publications

References 20 publications

Instrumentation for X‐Ray Spectrometry

Instrumentation for X‐Ray Spectrometry

Evaluation of a practical background calculation method in X‐ray energy analysis

Παραγωγη Μονοχρωματικων Δεσμων Ακτινων Χ Απο Πρωτονια Και Χρηση Τους Σε Αναλυτικες Εφαρμογες

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