Development of a water Cherenkov neutron detector for the active rotation method and demonstration of nuclear material detection

The active rotation method is an innovative, transportable, active neutron method suitable for on-site detection of concealed nuclear material. Its assay system consists mainly of a neutron detector and a rotation device for rotating a neutron source such as californium-252. Although we previously demonstrated a low-cost rotation device, the neutron detector bank comprising helium-3 proportional counters was extremely expensive and had low detection efficiency, leaving the challenges of reducing cost and measurement time. In the present study, we developed a water Cherenkov neutron detector as a novel neutron detector for the active rotation method and demonstrated its suitability and effectiveness for nuclear material detection, meeting the cost, efficiency, and transportability criteria for nuclear security.