Comparative optimization of Be/Zr(BH4)4 and Be/Be(BH4)2 as 252Cf source shielding assemblies: Effect on landmine detection by neutron backscattering technique

Monte Carlo simulations were used to model a portable Neutron backscattering (NBT) sensor suitable for detecting plastic anti-personnel mines (APMs) buried in dry and moist soils. The model consists of a 100 MBq Cf-252 source encapsulated in a neutron reflector/shield assembly and centered between two He-3 detectors. Multi-parameter optimization was performed to investigate the efficiency of Be/Zr(BH4)(4) and Be/Be(BH4)(2) assemblies in terms of increasing the signal-to-background (S/B) ratio and reducing the total dose equivalent rate. The MCNP results showed that 2 cm Be/3 cm Zr(BH4)(4) and 2 cm Be/3 cm Be(BH4)(2) are the optimal configurations. However, due to portability requirements and abundance of Be, the Cf-252-2 cm Be/3 cm Be(BH4)(2) NBT model was selected to scan the center of APM buried 3 cm deep in dry and moist soils. The selected NBT model has positively identified the APM with a S/B ratio of 886 for dry soils of 1 wt% hydrogen content and with S/B ratios of 615, 398, 86, and 12 for the moist soils containing 4, 6, 10, and 14 wt% hydrogen, respectively. The total dose equivalent rate reached 0.0031 mSv/h, suggesting a work load of 8 h/day for 806 days within the permissible annual dose limit of 20 mSv. (C) 2022 Korean Nuclear Society, Published by Elsevier Korea LLC.

Automated summary

Monte Carlo simulations were used to model a portable Neutron backscattering (NBT) sensor for detecting plastic anti-personnel mines (APMs) buried in dry and moist soils. The optimal configuration was determined through parameter optimization, and the sensor was tested for detection.