Performance of Linear PSD Methods on α/γ Discrimination for LaBr3 : Ce Scintillation Detectors with Different Sampling Properties

摘要

LaBr3 scintillation detectors are widely used in energy and TOF measurement for its excellent energy resolution and time resolution. However, due to the effect of intrinsic radioactive isotopes like Ac-227 in LaBr3, it’s important to discriminate the alpha background from high energy gamma-rays in low activity measurement. Generally, the pulse shape discrimination (PSD) methods are necessary to be deployed in this measurement situation to achieve this target. Therefore, how to choose a PSD algorithm and corresponding data acquisition system (DAQ) naturally becomes a critical problem to settle down. In this paper, the relationship between the classification performance of different PSD algorithms and digitizers’ sampling properties (sampling rate and effective number of bits) has been researched based on a LaBr3 scintillation detector. A self-developed integrated digitizer system with 6 different ADCs is deployed to digitize the waveforms, and three PSD algorithms, charge comparison method (CCM), least square for classification method (LS) and Fisher’s linear discriminant analysis (LDA), based on linear model are also applied. With the LDA method and a 125 MSPS 16-Bit ADC, the figure-of-merits (FoM) value is , which is similar to the discrimination capability from LS but much better than CCM. The results of this paper may be helpful for the developers of detector system to make a trade-off among DAQ’s sampling properties, desirable discrimination performance and cost of system.