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Title: High-Purity Germanium Spectroscopy at Rates in Excess of 10^{6} Events/s

Abstract—In gamma spectroscopy, a compromise must be made between energy resolution and event-rate capability. Some foreseen nuclear material safeguards applications require a spectrometer with energy resolution typical of high purity germanium (HPGe) detectors, operated at rates up to and exceeding 106 events per second. We report the performance of an HPGe spectrometer adapted to run at such rates. Our system consists of a commercial semi-coaxial HPGe detector, a modified high-voltagerail, resistive-feedback, charge-sensitive preamplifier and a continuous waveform digitizer. Digitized waveforms are analyzed offline with a novel time-variant trapezoidal filter algorithm. Several time-invariant trapezoidal filters are run in parallel and the slowest one not rejected by instantaneous pileup conditions is used to measure each pulse height. We have attained full-widthat- half-maximum energy resolution of less than 8 keV measured at 662 keV with 1:08*106 per second incoming event rate and 38% throughput. An additional constraint on the width of the fast trigger filter removes a significant amount of edge pileup that passes the first pileup cut, reducing throughput to 26%. While better resolution has been reported by other authors, our throughput is over an order of magnitude higher than any other reported HPGe system operated at such an event rate.
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Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0018-9499; NN2001000
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: IEEE Transactions on Nuclear Science; Journal Volume: 61; Journal Issue: 5
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
Country of Publication:
United States
germanium, semiconductor radiation detectors, gamma-ray detectors, digital filters, finite impulse response filters, signal processing algorithms, spectroscopy, nuclear electronics, preamplifiers