Applications in energy spectrum measurement based on pulse fitting

IntroductionThe parameters of detector can play important roles in analyzing the nuclear pulses. When getting these parameters, we can establish the mathematical model of the detector output signal and then achieve amplitude, time and other information of pulse simultaneously by one measurement, which can further improve the utilization of the signal.
Purposes and methodsIn this paper, one 500 MHz digitization card was used to measure the pulses of a scintillator detector, and a bi-exponential mathematical model was used to fit the shape of the pulse, from which the decay time of the scintillator as well as the time constant of the PMT can be well obtained. Based on these parameters, the accurate energy spectrum measurement and the reconstruction of piled-up pulses are studied on.
ResultsIt was experimentally verified that this method can significantly improve the energy resolution, up to 6.31% at 661.7 keV for NaI detector (ϕ 40 mm × 40 mm). In addition, the piled-up pulses are well reconstructed.
ConclusionsFor detectors with a single fluorescence decay time, a bi-exponential model can be set and used to fit the output pulse to get the parameters of the detectors. This model can be applied to obtain energy spectrum, reconstruction pulse of pile-up and so on.