A TUBE-EXCITED X-RAY-FLUORESCENCE SPECTROMETER FOR USE IN SMALL-DIAMETER BOREHOLES

A portable in-situ x-ray fluorescence analytical system that uses an x -ray tube excitation source and a cooled Si(Li) spectrometer for detec ting characteristic emission x rays has been developed for use in smal l-diameter wells and boreholes. The 15-watt, iron-anode x-ray tube ope rates up to 30 kV. Three wells at the Sandia National Laboratory Chemi cal Waste Landfill, lined with 76 mu thick polyethylene, were logged s pecifically for Cr contamination. Detection limits below 50 ppm were a chieved with counting intervals of 600 seconds and with the Si(Li) det ector operating at 450-eV resolution (full width at half maximum [FWHM ] for the Mn K-alpha x ray).