Study on the design of shielding of low-background anti-compton measurement system

Objective: According to the natural radiation sources, a set of shielding for the low-background anti-compton measurement system is designed. Methods: The model of detector and shield is established by Geant 4 Monte Carlo program. The main natural background radiation is input into the program as the source term. The structure and size of shield for the low-background anti-compton measurement system were simulated and optimized. The simulation results were verified by experimental measurements. Results: The shielding structures of 10 cm lead, 8 cm boron-containing polyethylene, 2 cm lead, and 1 mm oxygen-free copper lining from outside to inside were de termed. The experimental results are in good agreement with the simulation results, and the laws reflect consistency. The integrated background counting rates in the measured energy range of 50 ∼ 2000 keV was 1.72 cps. Conclusion: The structure and size of shielding layer of the low background anti-compton measurement system are optimized, and by adding boron-containing polyethylene interlayer to reduce the background count rates caused by thermal neutrons and fast neutrons. The experimental results verified the rationality and feasibility of the design scheme. (authors)