Digital discrimination of neutrons and γ rays with organic scintillation detectors in an 8-bit sampling system using frequency gradient analysis

Abstract

The feasibility of using frequency gradient analysis (FGA), a digital method based on Fourier transform, to discriminate neutrons and γ rays in the environment of an 8-bit sampling system has been investigated. The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system. However, the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and γ rays in the above sampling system. A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator. A comparison of the discrimination results of the time-of-flight and conventional charge comparison (CC) methods proves the applicability of this technique. Moreover, FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.