Low X-Ray Energy Fluorescence Gas Electron Multiplier (GEM) for XAS Studies

X-ray absorption spectroscopy at sub-keV energies dictates the use of detectors that can attain a good signal-to-noise ratio. We report a recent study undertaken at Science and Technology Facilities Council, Daresbury Laboratory to evaluate the performance of a gas electron multiplier (GEM) for this purpose. The main impetus of this study was to investigate the relevant parameters such as the effective gain and energy resolution in the X-ray energy range of 270-930 eV. This study demonstrated that a single stage GEM can sustain effective gains up to 60,000 in a helium-isobutane counter gas mixture at atmospheric pressure. Consequently, high signal-to-noise ratios were achieved (electronic noise electrons r.m.s) thereby permitting adequate X-ray energy resolution.