High Efficiency Semiconductors for Nuclear Material Accounting

There is a need to develop tools and technologies to improve the detection of diversion, misuse, or sabotage of nuclear materials in nuclear and pyroprocessing facilities. To address this need, the DOE Materials Protection, Accounting, and Control Technologies (MPACT) campaign set a goal of demonstrating a lab- scale of an advanced safeguards and security system for identification and localization of nuclear materials. Neutrons and gamma rays are two signatures of nuclear materials, therefore radiation detectors would be a key in developing these tools and technologies. A dual neutron/gamma-ray detection system can be used to monitor nuclear material and develop radiation maps for material that is dispersed throughout nuclear and pyroprocessing facilities. The detection of neutrons directly indicate the presence of special nuclear materials (SNM), while gamma ray detection can confirm the presence of specific isotopes. RMD is investigating the use of two different semiconductor materials, CsPbBr3 and LiInSe2, that can provide these capabilities in a compact and robust form-factor, combined with exceptional detection performance. Key processes related to crystal growth and detector fabrication of both detector types were investigate and improved. Crystal growth by Vertical Bridgman and Zone Melting were successfully implemented with promising results. The materials’ physical, chemical and electronic properties were fully characterized. Advances were made in both gamma ray spectroscopy with CsPbBr3 and neutron detection with LiInSe2. To increase neutron sensitivity 6Li enriched Li was used to synthesize LiInSe2. In Phase I, two new semiconductor detector technologies, CsPbBr3 gamma ray spectrometers and LiInSe2 neutron detectors were investigated and improved. The Phase II will focus on developing a dual-mode radiation detection prototype instrument for materials accounting. This will include optimization of both materials, the development of manufacturing processes, engineering electronic circuitry for reading the detector signals, development of detector control and data processing algorithms, and the design and construction of a complete prototype instrument that can be tested in a processing facility. In parallel, we will initiate technology commercialization efforts to add these detectors to our commercial product lines. The most relevant benefit of CsPbBr3/LiInSe2 radiation detection systems is improving the quality of and reducing the time required for mapping, tracking and controlling the nuclear materials in nuclear and pyroprocessing facilities. Other areas that will greatly benefit from compact dual mode semiconductor based systems are nuclear security personnel in DOE, DOE, IAEA, and CBP, and first responders