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

Developments in Analog-to-Digital Converters (ADC) in the last five years have enabled discrimination between pulses of various particles (e.g. neutrons and photons) in the digital domain 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 Programmable Gate Array (FPGA) and can be reprogrammed at any time providing the capability to extract all the quantities of interest. One weakness of current discrimination algorithms is a lack of capability 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 more than 60 % of the data is lost. In the present research we propose a method for pile-up events discrimination that provide also a new possibility of the simultaneous identification of mal- functioning detectors if a few detectors are utilized in the system. The timely detection of incorrectly working detection units is of main importance for number of traditional and novel multichannel (detectors) installations. To accomplish these goals we propose to use correlation coefficients and wavelets. In [2] it was shown that the use of the correlations of the incoming signal to the gamma average template in general lead to the improvement of the probability of detection of low energy pulses. In our present investigations we have showed that the use of correlation coefficients together with true pulse shapes, but separately for neutrons and gam- mas, provided a feasible method for the discrimination between neutron and gamma pile-up events in scintillation detectors with a simultaneous identification of malfunctioning detectors. In this paper the results of experimental evaluation of the testing of the proposed approach are described for identification of malfunctioning detectors and partly for discrimination between neutrons and gammas. Although, an optimized treatment of discrimination between neutrons and gammas signals with inclusion of overlaps by this technique will be discussed in further publications.