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Combined XRD and XRF Analysis for Portable and Remote Applications

Published online by Cambridge University Press:  06 March 2019

Jonathan A. Kerner
Affiliation:
Advanced Research and Applications Corporation 425 Lakeside Dr., SunnyvaleCalifornia 94086
Edward D. Franco
Affiliation:
Advanced Research and Applications Corporation 425 Lakeside Dr., SunnyvaleCalifornia 94086
John Marshall
Affiliation:
SETI Institute, Mountain View, California
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Abstract

A prototype instrument, which provides x-ray powder diffraction and x-ray fluorescence analysis in a compact unit, has been developed to support the needs of NASA for planetary exploration. The instrument uses a 9-watt Fe-anodc x-ray tube and CCD in a fixed geometry for recording powder patterns with a 2θ range of 35°. The fluorescence spectrum for elements below Fe is collected simultaneously with the diffraction data. A shuttered Cd-109 isotopic source with emissions at 22 and 80 keV is used to excite higher energy fluorescence.

The low-energy limit for discriminating single photon events was found to be ∼1.5 keV. Al-K could be distinguished from a pure sample, but the spectrum below 6 keV was degraded by the read noise of the CCD, which introduced spectral artifacts. Diffraction peaks from halite had a FWHM of ∼1°(2θ), with major contributions to the width from the use of slit collimation on the source and the low tilt angle of the sample.

Type
IV. New Developments in X-Ray Sources, Instrumentation and Techniques
Copyright
Copyright © International Centre for Diffraction Data 1994

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