Improving the performance of radiological and nuclear detection technology is critical to enhancing our ability to detect and interdict nuclear threats. The passive detection of fast neutrons is a strong indicator of the presence of certain nuclear materials such as weapons grade plutonium. Fast neutron detection also supports enhanced detection of shielded special nuclear material in various active detection approaches. Liquid and plastic scintillators have traditionally been used for fast neutron detection, but have limited detection performance and often encounter issues with handling and storage. Solid crystalline organic scintillators provide performance improvements over the liquid and plastic scintillators, but have been only available through foreign suppliers and at high costs and limited sizes. To address these issues, the Domestic Nuclear Detection Office’s Exploratory Research and Small Business Innovative Research programs have supported the development by industry of stilbene, a solid organic scintillator material with exceptional performance for detecting fast neutrons.
Stilbene is an organic crystalline scintillator material that emits light upon interaction with nuclear radiation. The presence of radiation can be determined by coupling the stilbene crystal to a light detector. Analysis of the light signal allows the identification of fast neutrons and the system can alert the user to the potential threat.
Through an innovative, low-temperature, solution growth process, large volume crystals of stilbene are providing:
- High fast neutron detection sensitivity;
- Excellent discrimination between fast neutrons and gamma rays, enabling clear neutron detection in high gamma-ray backgrounds;
- Solid, low stress, non-hygroscopic, non-flammable, and non-hazardous material, enabling ease of use and handling; and
- A variety of geometries to cover different application spaces and address customer specifications.
The company behind the development of the innovative growth processes has recently announced the commercial availability of stilbene in small volumes. Although the customer base is still developing, the initial response from recipients of stilbene crystals has provided positive feedback on quality and performance.