Discrete Fourier Transform Method for Discrimination of Digital Scintillation Pulses in Mixed Neutron-Gamma Fields

摘要

A Discrete Fourier Transform Method (DFTM) for discrimination between thesignal of neutrons and gamma rays in organic scintillation detectors ispresented. The method is based on the transformation of signals into thefrequency domain using the sine and cosine Fourier transforms in combinationwith the discrete Fourier transform. The method is largely benefited fromconsiderable differences that usually is available between the zero-frequencycomponents of sine and cosine and the norm of the amplitude of the DFT forneutrons and gamma-ray signals. Moreover, working in frequency domain naturallyresults in considerable suppression of the unwanted effects of various noisesources that is expected to be effective in time domain methods. The proposedmethod could also be assumed as a generalized nonlinear weighting method thatcould result in a new class of pulse shape discrimination methods, beyonddefinition of the DFT. A comparison to the traditional Charge IntegrationMethod (CIM), as well as the Frequency Gradient Analysis Method (FGAM) and theWavelet Packet Transform Method (WPTM) has been presented to demonstrate theapplicability and efficiency of the method for real-world applications. Themethod, in general, shows better discrimination Figure of Merits (FoMs) at boththe low-light outputs and in average over the studied energy domain. A noiseanalysis has been performed for all of the abovementioned methods. It revealsthat the frequency domain methods (FGAM and DFTM) are less sensitive to thenoise effects.