The Study Of The Light Pulse Distributions Induced By Fast Neutrons In Organic Scintillator

Currently, neutron detection technology is an important hot topic in the field ofnuclear security technology at home and abroad. Generally, neutron detections can bedivided into two categories: one is to measure neutron fluence rate; the other is tomeasuring the neutron energy spectra. There are mainly two options of neutron energyspectrometry: time-of-flight spectra and pulse height spectra, respectively. For safeguardspurposes, especially in field applications, neutron spectrometry by unfolding the light pulseheight distributions has definite advantages over the time-of-flight method.This paper mainly through two methods: analytical calculation method and MonteCarlo simulation method to analyze the data of light pulse distribution generated by theinteractions between fast neutrons and the composition materials of organic scintillator.The analytical method doesn’t need to consider the simplifications of detector geometry orthe neutron/gamma discrimination, but some reasonable approximations in the analysisprocess. The main works are as follows:1. By means of analytical method, we analyzed the neutron collision history with Hand C atoms in the organic scintillator step-by-step, so that the whole physical processsimple and transparent. Analytic process is mainly divided into the following steps:First, we obtained the distribution of deposited energy of single collision on H and Catoms, and thereby obtained the light pulse distributions generated by single collision.Second, we got the light pulse distribution of the whole collision history of single neutron.Finally, the total light pulse distributions generated by the entire neutron collision historywas obtained, according to the probability of the collision sequence.2. Through Monte-Carlo method, three monoenergetic neutron sources with energies1,1.5and2MeV and two continuous neutron sources: Am-Be source the252Cf neutronsource were simulated. the light pulse distributions generated by the interactions betweenfast neutrons and liquid scintillator were obtained. And a comparison of light pulsedistributions generated by specific collision history between Monte-Carlo simulation andanalytical method, the result shows that both have good agreement. This validates thefeasibility of using analytical method to calculate the light pulse distributions generated by fast neutrons in the organic scintillator.