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Proceedings Paper

X-ray flux concentrating optics for improving the performance of light element energy dispersive spectroscopy
Author(s): David B. O'Hara
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Paper Abstract

Frequently, EDS (Energy Dispersive Spectrometer) x-ray detectors cannot be placed very close to an x-ray source for microanalysis causing the detector to subtend a small solid angle thus reducing the available count rate. This is exacerbated by low count rates for the light elements and situations where low energy spectral lines are immersed in a background of higher energy x-rays from heavier elements. Larger detectors can be used at the expense of resolution but in many situations there is insufficient room for a large detector so a 10 mm2 detector is used. Notch filters can sometimes be used to minimize higher energy counts but they do not allow a broad spectrum of low energy x-rays to pass and still allow passage of the highest energy x-rays to the detriment of light element detection. We have developed low energy x-ray optics which increase the solid angle seen by EDS detectors and can also act as low pass filters preferentially allowing passage of low energy x-rays. In a typical situation where 10 mm2 detectors are used with a 35 mm distance between x-ray source and detector surface, our optics can provide a flux gain of about 22X for B (Boron) x-rays with gain decreasing toward unity at energy above O (Oxygen at 525 eV) with gain remaining at unity for higher energy. In other words, we greatly increase the performance at the lowest energies without affecting the higher energies.

Paper Details

Date Published: 17 December 1998
PDF: 7 pages
Proc. SPIE 3443, X-Ray and Ultraviolet Spectroscopy and Polarimetry II, (17 December 1998); doi: 10.1117/12.333603
Show Author Affiliations
David B. O'Hara, Parallax Research, Inc. (United States)

Published in SPIE Proceedings Vol. 3443:
X-Ray and Ultraviolet Spectroscopy and Polarimetry II
Silvano Fineschi, Editor(s)

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