A Low Power X-Ray Diffractometer for Soil Analysis in Remote Locations Employing a Multiwire Proportional Counter Detector Array

A low power x-ray powder diffraction system suitable for remote mineralogical analysis of lunar, planetary, or asteroid soils has been designed. A one Curie 55Fe source provides a monochromatic x-ray beam of 5.9 keV. Seeman-Bohlin or focusing geometry is employed in the camera, allowing peak detection to proceed simultaneously at all angles and obviating the need for moving parts. The detector system is an array of 500-600 proportional counters with a wire-spacing of 1 mm. An electronics unit comprising preamplifier, postamplifier, window discriminators and storage flip-flops requiring only 3.5 milliwatts has been designed and tested. Total instrument power is less than 5 watts. Powder diffraction patterns using a flat breadboard multiwire counter have been recorded.