Energy - dispersive x-ray fluorescence systems are characterized by limited count rate capability, which is an important practical limitation on their application. This arises from two factors: 1) The amplifier time constant is many times greater than needed in wavelength-dispersive systems, in order to permit accurate measurement of pulse height, and reducing the time constant degrades system resolution; 2) x-ray pulses from ail the major and minor elements, as welt as scattered background and/or peaks from the incident radiation, must all be processed, reducing further the effective count rate for a single element of interest. Hence there has been a strong desire to find ways to increase the count rate capability of energy-dispersive systems.