A method for discrimination of neutron and gamma pile-up events in scintillation detectors with a simultaneous identification of malfunctioning ones

AbstractDevelopments in Analog-to-Digital Converters (ADC) in the last ve years have enableddiscrimination between pulses of various particles (e.g. neutrons and photons) in the digitaldomain in real time. The big advantage of digitizers compared to the traditional acquisition sys-tems is that the Digital Pulse Processing algorithms are implemented in a Field ProgrammableGate Array (FPGA) and can be reprogrammed at any time providing the capability to extractall the quantities of interest. One weakness of current discrimination algorithms is a lack ofcapability to process pile-up events; usually they are just rejected by the system. However,when working with high-count rates [1], a rejection of pile-up events can lead to that morethan 60 % of the data is lost. In the present research we propose a method for pile-up eventsdiscrimination that provide also a new possibility of the simultaneous identi cation of mal-functioning detectors if a few detectors are utilized in the system. The timely detection ofincorrectly working detection units is of main importance for number of traditional and novelmultichannel (detectors) installations. To accomplish these goals we propose to use correlationcoecients and wavelets. In [2] it was shown that the use of the correlations of the incomingsignal to the gamma average template in general lead to the improvement of the probability ofdetection of low energy pulses. In our present investigations we have showed that the use ofcorrelation coecients together with true pulse shapes, but separately for neutrons and gam-mas, provided a feasible method for the discrimination between neutron and gamma pile-upevents in scintillation detectors with a simultaneous identi cation of malfunctioning detectors.In this paper the results of experimental evaluation of the testing of the proposed approach aredescribed for identi cation of malfunctioning detectors and partly for discrimination betweenneutrons and gammas. Although, an optimized treatment of discrimination between neutronsand gammas signals with inclusion of overlaps by this technique will be discussed in furtherpublications.1. IntroductionThe problem of unsuspected malfunctioning of the scintillation detectors/cameras and/orother multichannel radiation detection systems is relevant for a number of various elds, med-ical, nuclear etc. Generally, to detect any abnormal behavior of the detection systems theuniformity test of the system is performed by using various radiation sources. The uniformitytest normally reveals most of malfunctions of detection array, however, some cases are stillremain dicult to identify. One of these cases is related to the situation when although, a1