Digital pulse deconvolution algorithms for radiation detection systems: a comparison study

Purpose Radiation detector signals are processed by preamplifiers to produce amplified and stretched pulses. However, this also increases the likelihood of pulse overlap, known as pile-up. Digital processing modules have enabled the unfolding-synthesis strategy for pulse processing, where digitized preamplifier output pulses are deconvoluted into impulse signals, then formed to the shape of interest, in order to reduce the pile-up effect.
Methods The present study compares several unfolding algorithms for mono- and bi-exponential pulses. For smoothing signals, two strategies are considered: a successive application of moving mean and moving median filters, and Savitzky-Golay filtering. Both simulated and experimental pulses from an NaI(Tl) detector are taken into account. Savitzky-Golay filtering is shown to enhance pulse amplitude (energy) resolution but offers weaker noise filtering than the mean-median strategy.
Results and Conclusion Results show that algorithms based on the bi-exponential pulse assumption produce signals closer to impulse, in order to preserve more pulses at the expense of pulse amplitude resolution, while those based on the mono-exponential assumption generally give signals of width at least equal to the rise time of the input pulse. A proposed bi-exponential-based algorithm introduces a tunable term for a balanced solution.