Comparisons between digital gamma-ray spectrometer (DSPec) and standard nuclear instrumentation methods (NIM) systems

Abstract

Up until about a year ago, gamma-ray spectroscopy has always been done using the analog amplifier, which processes the pulses from the preamplifier to remove the noise, reject the pile-up signals, and shape the signals into some desirable form before sending them to the analog-to-digital converter (ADC) to be digitized. In late 1996, EG&G Ortec introduced a digital gamma-ray spectrometer (DSPec) which uses digital technology to analyze the preamplifiers' pulses from all types of germanium and silicon detectors. Considering its performance, digital-based spectroscopy may become the way of future gammaray spectroscopy.

Extended Evaluations of the Commercial Spectrometer Systems for Safeguards Applications

“…The DSPEC used the general-purpose parameters for germanium detectors [1], cusp value of 0.8 and flattop value of 1.6 p.s, throughout these measurements. For the 2060DSP, the flattop values for these detectors were automatically optimized by the BDC and they turned out to be 0.8~s and 0.5 MSfor the coaxial and planar detectors used in the evaluation, respectively.…”

“…Note that the performances of the DSPEC and 2060DSP can even be improved more if the BLRs are distinctively set to accommodate different count rates instead of "auto" as was done in the evaluation. In addition, the parameters used for the advanced shaping of the DSPEC were the general-purpose parameters [1]. If one can individually adjust the parameters for optimal performance for each different radiation source at different count rates, then the results for DSPEC would be even better.…”

“…For the NIM system, as before, the pulse shape was set to the triangular shaping. For the DSPEC, the general-purpose parameters [1], cusp of 0.8 and flattop of 1.6 ps, could be used in the test. However, since this detector has a much larger efficiency and the pulses of this detector have much longer decay time than those of the 25% detector, it was thought best if the optimal parameters for this 929i0 detector were found.…”

“…The general-purpose parameters [1], cusp of 0.8 and flattop of 1.6 ps, were used in the test. The rise time was set at 4-ps, which would roughly correspond to 2-~s shaping time of the NIM systems.…”