| Past 3He shortages have led to investigations into 3He-free technologies for neutron detection applications that have often been accommodated by 3He-based technologies. The goal of the Alternative Multiplicity Counter Project was to investigate 3He-free technologies for neutron multiplicity counting for safeguards applications. Of the technologies investigated, lithium fluoride with silver-activated zinc sulfide scintillator (LiF/ZnS) was identified as the most promising material for developing 3He-free neutron multiplicity counters. This project has successfully designed, built, and tested a lithium fluoride with zinc sulfide-based neutron multiplicity counter with a high neutron detection efficiency, short neutron die-away time, and low gamma-ray sensitivity. LiNMC design and construction involved optimizing scintillator and moderator materials, photomultiplier tube (PMT) size, number, shape and location, detector dimensions, optical reflector materials, and gamma-ray discrimination methods. By the end of the project, the LiNMC’s basic components have been brought together and validated, achieving technological readiness level four, and providing strong evidence that LiF/ZnS-based neutron detection is viable technology for development into a high performance 3He-free neutron detector. Preliminary calibration with 252Cf showed that the LiNMC was able to achieve a 39% neutron detection efficiency and a 13.2 μs neutron die-away time, resulting in FoM of 120. Preliminary calibration with 137Cs and 60Co showed that the LINMC was able to achieve a gamma-ray detection efficiency as low as 1.5×10-3 . Increases in neutron detection efficiency, reductions in neutron die-away time, and reductions in gamma-ray sensitivity are anticipated to be achievable with further development |