R&D of Passive Fast Neutron Multiplicity Counting System Based on Liquid Scintillation Detectors

The system also integrates a self-designed and developed 32-channel high-voltage power supply and a user-friendly graphical interface. Secondly, the Doubles parameter fitting method and the three-parameter fast neutron multiplicity analytical method are used to evaluate the spontaneous fission rates of the 252Cf neutron sources respectively. Finally, the performance of the system under different neutron radiation backgrounds (with Singles rates of 111.42±0.46, 73.97±0.28, and 47.27±0.29, respectively) was also evaluated.

[Results]: The experimental results show that the Doubles parameter fitting method can accurately evaluate the spontaneous fission rates of 252Cf neutron sources. The relative differences of the spontaneous fission rates of the 252Cf neutron sources evaluated by using the fast neutron multiplicity analytical method are less than ±4%. The measurement results under different neutron radiation backgrounds are basically consistent with those under natural environment background (the Singles rates were 0.51±0.02).

[Conclusion]: The FNMC system can accurately determine the spontaneous fission rate of the 252Cf neutron source (with an equivalent 240Pueff mass range of 5.37-209.62g), and has very good anti-background interference capabilities.