Use of Feedback to Maximize Photon Count Rate in XRF Spectroscopy

Abstract

The effective bandwidth of an energy dispersive x-ray fluorescence spectroscopy system is limited by the timing of incident photons. When multiple photons strike the detector within the processing time of the detector photon pile-up occurs and the signal received by the detector during this interval must be ignored. In conventional ED-XRF systems the probability of a photon being incident upon the detector is uniform over time, and thus pile-up follows Poisson statistics. In this paper we present a mathematical treatment of the relationship between photon timing statistics and the count rate of an XRF system. We show that it is possible to increase the maximum count rates by applying feedback from the detector to the x-ray source to alter the timing statistics of photon emission. Monte-Carlo simulations, show that this technique can increase the maximum count rate of an XRF spectroscopy system by a factor of 2.94 under certain circumstances.