Discrimination of neutrons and gamma-rays in plastic scintillator based on falling-edge percentage slope method

With the development of neutron detection technology, the demand for real-time and fast neutron gamma discrimination has become of increasing importance. In this study, neutron and gamma pulse signals measured by an EJ299-33A plastic scintillator detector were analyzed via Matlab off-line. This study compares the effects of seven fast neutron and gamma (n/gamma) discrimination methods; (i) charge comparison method, (ii) time-domain oriented method, (iii) amplitude oriented method, (iv) pulse time-amplitude two types of width method, (v) angle difference method, (vi) falling-edge numerical integral method, and, lastly, (vii) falling-edge percentage slope method proposed in this study. We verified that filtering and amplitude normalization improve the discrimination quality but consume much time that accounts for 99.6% of the total discrimination time. The proposed method was compared with other six methods in two aspects: (i) the figure of merit (FoM), (ii) the discrimination time. The FoM value and time consumption of the falling-edge percentage slope method with amplitude normalization are 1.26 and 0.0621s, respectively, while an unnormalized FoM value is 1.02. Experimental results showed that compared with all aforementioned methods, the FoM value of our proposed method is the second high followed the charge comparison method, retaining a short discrimination time which is only half of that of the charge comparison method. This relatively short time consuming is on account of its low volume of data storage and calculation. Generally, the falling-edge percentage slope method has a good discrimination performance while consumes little time, which is capable to be implemented on real-time discrimination applications.