S IMULTANEOUS XRD/XRF WITH LOW-POWER X-RAY TUBES

Abstract

A test bench instrument constructed at MOXTEK, Inc. is capable of simultaneously capturing X-ray diffraction (XRD) and X-ray fluorescence (XRF) information using a charge-coupled device (CCD) as the X-ray detector. NASA is funding the instrument’s construction because of its low-power consumption and compact size; it could be used for in-situ planetary exploration missions for mineral analysis. A powdered sample of material is placed in front of the CCD. A collimated X-ray beam bombards the sample, and the CCD captures the scattered X-ray events. Sorting algorithms are used to separate the XRF and the XRD information captured by the CCD. A small low-power X-ray source is needed to make the device portable. We have examined the instrument with a rotating-anode tube, a commercially available Svetlana transmission tube, and two miniature low-power prototype tubes constructed at MOXTEK. The data capturing rates were compared for the different sources. We have verified the feasibility of capturing both XRF and XRD with the MOXTEK source, using under five watts for both the tube and its high-voltage power supply.