Description:
OUSD (R&E) MODERNIZATION PRIORITY: General Warfighting Requirements (GWR); Nuclear Modernization
TECHNOLOGY AREA(S): Nuclear; Sensors
OBJECTIVE: DTRA seeks technologies to replace large form-factor Sodium Iodide (NaI) logs to support next-generation Department of Defense (DoD) mobile radiation detection systems. Ideal systems will provide leap-ahead capability advancements over existing systems at up to 4” x 4” x 16” form factors with gamma energy resolution and cost less than or equal to NaI. Specifically, these leap-ahead capability advancements in these large form factors may include, but are not limited to (1) single material fast neutron and gamma detection using pulse shape discrimination (PSD), (2) improved tolerance to shock, vibration, and/or environmental conditions, such as humidity, that would be expected during DoD operations, (3) decay times less than 10 nanoseconds to enable operations in higher dose environments, (4) integrated light-guide technologies to enable source localization via occlusion and operations in higher dose environments, (5) significant reductions in cost or gamma energy resolution compared to NaI. The ability to provide incident neutron energy spectra in a single scintillator element (i.e. without time-of-flight) by unfolding the neutron light-output spectra is also a desired feature.
DESCRIPTION: NaI, Cesium Iodide (CsI), Polyvinyl Toulene (PVT), and other plastic scintillators have been the state-of-the-art in large form-factor radiation detection materials; however, each of these materials has significant limitations. NaI, for example, is not well-suited to exposure to DoD shock, vibration, and environmental conditions due to its proneness to fracturing and hygroscopic nature. PVT suffers from poor energy resolution, which limits isotope identification performance. For compact detection systems, elpasolites such as CLYC and CLLBC have enabled thermal neutron detection and gamma spectroscopy in a single crystal, but the crystals remain relatively small with limited potential to scale to these form factors.
The recent development of organic scintillating glass (OSG) materials [1] has shown a promising glimpse into a future where is one example where a single material may be PSD-capable, melt-cast into multiple shapes, inexpensive, and well-performing against the best scintillator materials currently available commercially [2]. Other nascent radiation detection materials, such as Perovskites, continue to show promise as inexpensive materials with extremely good energy resolution. Desired solutions are not limited to just scintillator technologies and may include alternate approaches as long as the form factor and capability enhancement objectives of this topic are met.
PHASE I: Demonstrate the ability to create 2” x 4” x 6” scintillator detector material samples exhibiting some of the desired capability enhancements listed in the objective section of this topic. Initial testing of the scintillator material should be conducted, compared against NaI, and results should be documented and provided in the final report. A plan should also be submitted outlining the approach for scaling the system to meeting Phase II requirements.
PHASE II: Demonstrate the ability to create samples in multiple form factors up to 4” x 4” x 16” exhibiting two or more of the desired capability enhancements listed in the objective section of this topic. The samples should then be integrated with a commercial photomultiplier tube, solid-state photomultiplier, or other electronics (for non-scintillating solutions), as appropriate, and the resulting performance compared against equivalent NaI systems. The use of actual hardware and empirical data collection is expected for the performance analysis of the system and the results should be provided in the final report. A design plan should also be submitted outlining the plans for scaling the system to meet Phase III requirements.
PHASE III DUAL USE APPLICATIONS: Phase III will demonstrate fully capable sub-systems in multiple form factors up to 4” x 4” x 16” suitable for commercialization and achieving two or more of the desired capability enhancements listed in the objective section of this topic. All data collected during the demonstration and analysis of the final system will be included in the final report along with a user’s manual and a data package on all critical system components.
REFERENCES:
1. “Organic Glass for Radiation Detection”, https://ip.sandia.gov/techpdfs/Organic%20Glass%20for%20Radiation%20Detection.pdf, 2018;
2. Clark, L.M. et al, “Investigation of Organic Glass Scintillators for Improved Energy
Resolution for Radioxenon Detection”, MTV Workshop, 2021, http://mtv.engin.umich.edu/wp-content/uploads/sites/431/2021/03/20210330-0335-Clark.pdf;
KEYWORDS: Radiation; sodium iodide; scintillator; nuclear; scintillation; transverse Anderson localization; laser induced optical barriers
