High order fast neutron multiplicity measurement equations based on liquid scintillation detector

Fast neutron multiplicity counting (FNMC) analysis method is a new nondestructive analysis method for nuclear materials. It uses a fast neutron detector array to detect the neutrons emitted by the sample. The quality of plutonium in the sample is obtained by recording the neutron coincidence counting of fast neutron multiplicity. At present, the first three multiplets widely studied including singlets, doublets and triplets can no longer meet the needs of the research. In this paper, The derivation process of fast neutron multiplicity measurement equation for liquid scintillation detector is studied in detail based on the basic principle, neutron counting method, by using the methods of the factorial moments, probability generating functions and parameter estimation method, and considering the influence of scattering crosstalk. Finally, the fast neutron multiplicity measurement equation including singlets, doublets, triplets, quadruplets and pentuplets are established according to the parameter estimation method and the two kinds of solution methods of this equation are given. The work in this paper lays a theoretical and analytical foundation for the research of fast neutron multiplicity measurement system based on liquid scintillation detector.