Characterization of Commercial Lithium Zinc Sulfide and Boron Coated Straw Detectors as Helium - 3 Alternatives for Nuclear Safeguards and Security

Helium - 3 filled cylindrical proportional counters are efficient, reliable neutron detectors with excellent gamma rejection capability. In recent years, the reduction in He - 3 production and continuing high demand has led to a He - 3 shortage. This shortage has caused the detectors to become prohibitively expensive and difficult to obtain. The goal of this project is to test and evaluate current alternatives produced for some applications and deployed by two private companies. Cur rent testing is being done with a Lithium Zinc Sulfide ( 6 LiF:ZnS(Ag)) detector from Aspect, as used in their portal monitors, as well as a Boron Coated Straw (BCS) coincidence counter from Proportional Technologies Inc. Specific features such as radial res ponse (the response of the detector as a source moves past the face) and gamma rejection were tested with the detectors mentioned above, as well as comparisons to a current 3 He module through experimental measurements.