Effect of the LEGe detector collimators on K-series peaks and Compton scattering in XRF analysis using gamma rays

The effect of a low-energy germanium detector collimator with different diameters on the measurement of the X-ray fluorescence of palladium (Pd) was studied experimentally. Changes in the Pd K-series and Compton scattering peaks were measured and analysed with and without a detector collimator, where for the former, collimators with different diameters were used. The signal-to-noise ratio increased when a shielding collimator was used with a narrow detector collimator. The Compton dispersion and fraction dead time were reduced considerably using a detector collimator by increasing the distance from the source to the detector, and the collimator length-to-diameter ratio. The full width at half maximum (FWHM) of the Pd Kα1 and Pd Kβ1 peaks decreased almost linearly with the collimator length-to-diameter ratio. The FWHM illustrated that the spectral resolution was improved when a collimator with a smaller diameter but unchanged length was used. The uncertainties at the Pd Kα1, Pd Kβ1, and Compton dispersion peaks were approximately correlated linearly with the collimator length-to-diameter ratio.