French, R. M.; Thevenin, M.; Hamel, M. & Montbarbon, E.
A Histogram-Difference Method (HDM) for Neutron/Gamma Discrimination Using Liquid and Plastic Scintillators
IEEE Transactions on Nuclear Science, 2017, PP, 1-1

http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7961228

This paper introduces a novel and extremely simple – and therefore, easily implemented in a Field-Programmable Gate Array (FPGA) – method of neutron/gamma pulse discrimination called the Histogram-Difference Method (HDM). Crucially, this method relies on the use of a “reference set” of γ- only pulses from ²²Na, ¹³⁷Cs and ⁶⁰Co sources and on features extracted from the pulses. The pulses from this reference set are compared to a set of an identical number of n+γ pulses from a ²⁵²Cf source. Not only can HDM determine the presence of neutrons in the ²⁵²Cf source, but it can also estimate the approximate percentage of neutron pulses from that source. The results reported in this paper are based on data from different radioactive sources and a standard scintillator for this type of research – namely, BC-501A. These results were confirmed using three other scintillators, one made in-house, and two others that are commercially available, EJ-299-33 and EJ-200. Pulses were encoded using Q-values, which are features extracted from the pulses, i.e., (Qtotal, Qtail) pairs in IR². As a control, we also encoded pulses as the Root-Mean-Square (RMS) distances from the average pulse of all known γ-only pulses and ran HDM using these pulse representations. The results are very similar to those obtained using a Q-value encoding of the pulses.