Characterization of cadmium capture-gated detector for nuclear nonproliferation applications

Almost all commercially applied neutron-counting systems employ 3He tubes for detection of thermal neutrons. However, due to a large number of 3He systems deployed in the field, there is currently a severe shortage of 3He gas. Therefore, novel neutron detection systems are desirable, especially because a large number of detection systems are needed to meet current security demands. One class of detectors that has been explored is capture-gated scintillation detectors which consist of a standard scintillation detector (plastic or liquid) that has been modified to include a neutron capturing isotope. The capture-gated neutron-spectroscopy principle is based on the fact that a single neutron that interacts in a capture-gated detector can create two pulses that are related in time. In this work, we present simulation and measurement results for a cadmium/plastic-scintillator capture-gated detector. The detector consists of 13, 1-cm thick BC-408 plastic-scintillator layers and 12, 0.1-mm thick natCd layers. This detector possesses unique detection characteristics that could find use in nuclear nonproliferation applications.