Optimization of Coating in Boron-10 Lined Proportional Counters

In response to the global shortage of Helium-3 gas, various alternative technologies have been developed for the detection of neutrons. Boron-10 (B-10) lined proportional counters represent one alternative that has been developed by GE Reuter-Stokes and deployed in applications such as Radiation Portal Monitors. The formulation of the B-10 coating used in these detectors was designed to maximize the content of B-10 in the coating, and the thickness of the coating was initially optimized to maximize the sensitivity of an individual detector in a thermal neutron field. Further study has indicated the optimal coating thickness for an assembly of detectors differs from that of an individual detector. Here, we report on the results of optimization of B-10 coating thickness for systems containing various numbers of detectors in various moderator configurations. In this work, the relationship between coating thickness, number of detectors, and moderator design is investigated using MCNP modeling and experimental data. The effectiveness of optimizing coating thickness at the system level is demonstrated experimentally for a commercially available radiation portal monitor neutron detection module.