METHOD AND APPARATUS FOR BASELINE CORRECTION IN X-RAY AND NUCLEAR SPECTROSCOPY SYSTEMS

摘要

Techniques for measuring the baseline of the energy filter in nuclear and other spectrometers that filter pulses output by a preamplifier to measure the energy of events occurring in a detector connected to the preamplifier. These spectrometers capture the peak amplitudes of the filtered pulses as estimates of the underlying event energies and subtract a baseline value from these captured peak values in order to compensate for the energy filter's non-zero amplitude in the absence of any preamplifier output pulses. A second, baseline filter is connected to the preamplifier's output, where the basewidth of this baseline filter is significantly shorter than that of the energy filter. Times are determined when the baseline filter is not filtering preamplifier output pulses, output values from the baseline filter are captured during such determined times, and these baseline values captured from the baseline filter are used to create an accurate estimate of the energy filter's baseline value. Because the baseline filter's basewidth is much shorter than the energy filter's basewidth, large numbers of valid baseline filter values can be reliably captured at very high input count rates where it becomes difficult to capture baseline samples from the energy filter itself. It thus becomes possible to maintain the spectrometer's energy resolution and peak location stability to count rates four or more times higher than is possible without the method. The technique can be applied to both digital and analog spectrometers.