Solid-State Neutron Detector for Nuclear Material Accounting

Nuclear material accounting within the nuclear fuel cycle includes preventing and detecting theft or diversion of special nuclear material. Neutron detection by use of pressurized He-3 tubes is a critical component within the scheme of safeguarding nuclear materials. Due to the worldwide shortage and high demand of 3He supply, alternative neutron detection technologies are required to ensure and proper material management. RMD has developed a new scintillation material Cs2LiYCl6:Ce (CLYC) for dual neutron/gamma detection that is enriched with 6Li, providing a higher neutron sensitivity per unit volume than a typical He-3 tube due to the higher material density. When coupled to a state-of-the-art photodetector, digitizing electronics and processing algorithms, an advanced detector module provides a plug-and-play neutron detector that is readily implemented into existing, new or complex detector systems, reducing development cost of new instruments. The Phase-I program has demonstrated that typical sizes ranging from 1 to 5-cm cubic crystals are viable and can provide an accurate measurement within the assay time constraints within the paradigm of nuclear material accounting. CLYC can be coupled to a variety of high-gain detectors (APDs, SSPMs, MPPCs, or PMTs), but the super bialkali photomultipliers provide the best performance. The Phase-I program has developed a new method for identifying neutrons in a high-intensity, gamma-ray field with event rates exceeding 600 kHz. The Phase-II program will develop the detector scheme for a modular detector that provides digital information of incident events, where the signal processing is made within the digital domain. The detector will consist of a CLYC crystal, an analog to digital converter, an FPGA circuit, and i/o ports for control and streaming data. The hardware and software will be optimized for a CLYC based detector with a complete device evaluation using relevant nuclear materials. Commercial Applications and Other Benefits: CLYC has been identified as a replacement for He-3 tubes and provides excellent energy resolutions for scintillation materials for gamma-ray spectroscopy. This dual use sensitivity requires more processing of the signal waveforms not necessary of other types of materials, and this program solves this by implementing an adaptable framework from which to develop new instruments. The unit developed in this Phase-II program can implemented for nuclear material security, radiation detection, gamma and neutron imaging, calorimetry or spectroscopy within the fields of security, defense, science, and medicine.