Improvements in Scintillation Technology for Detection of Nuclear Radiation
Small Business Information
RADIATION MONITORING DEVICES, INC.
44 Hunt Street, Watertown, MA, 02472
AbstractOBJECTIVE: Develop innovative scintillator materials for the detection of gamma-ray or neutron radiation for a variety of applications. For handheld and arrayed detectors criteria for improvement include better energy resolution; higher light output (photons per MeV); improved linearity of light output; and smaller, more efficient and more rugged light readout technology to replace photomultiplier tubes and lower power consumption. For applications requiring detectors with very large volume, a low-cost material with significantly better energy resolution is required to replace plastic scintillators. DESCRIPTION: Scintillators that exceed lanthanum halides in brightness with energy resolution approaching the statistical limits for scintillator-based gamma-ray spectrometry are needed for a variety of applications that include handheld detectors and imaging arrays. The goal of this SBIR is to investigate the next-generation scintillators that will exceed the lanthanum halides in brightness (>90,000 photons/MeV) yet have adequate linear response to gamma-ray energies from 60 keV to 3 MeV. These new scintillators should also provide energy resolution of <= 2% (FWHM) at 662 keV. Photomultiplier tubes (PMT) currently utilized for light collection and amplification are based on vacuum tube technology requiring a high-voltage bias for operation and relatively high power consumption. In high mechanical stress environments typically encountered by the US military in field environments, these devices can fail. PMTs may also be too bulky to use in imaging detectors based on scintillator arrays. Another goal of this SBIR is to investigate reliability and performance improvements in scintillator light collection (SLC) technology and to match improved SLC technology with the next-generation scintillator materials. For example, photodiodes that can be fabricated with CMOS technology and that operate in avalanche mode are a promising technology. Gamma-ray energy resolution in low-cost, large-volume scintillators of <10% (FWHM) at 662 keV would be a significant improvement over currently available plastic scintillators. Promising technologies for large-volume scintillators include ceramic and composite scintillators consisting of granular scintillating material in an appropriate binder. Scintillator materials with sensitivity to neutron radiation are needed, but responses to neutrons must be clearly distinguishable from responses to gamma rays even in intense radiation fields. Because of their generally fast response and recovery times, scintillator detectors have potential application in pulsed active interrogation systems for location and identification of special nuclear materials. PHASE I: Develop new scintillator material(s) potentially useful for applications of interest to DTRA as identified above. Evaluate scintillation and electronic properties through laboratory measurements. Develop conceptual designs for matching SLC technology with the scintillator material and evaluate feasibility through laboratory testing of devices and components. Consider how the improved scintillating material might be produced in commercial-scale quantities. PHASE II: Develop a prototype scintillator detector incorporating new materials as described above and/or employing improved SLC technology. Demonstrate in a laboratory test and comparison with present scintillation detectors (e.g., NaI and La halide) employing PMTs. PHASE III DUAL USE APPLICATIONS: In addition to military applications, improved scintillator detector technology would have relevance in the medical industry for gamma cameras, positron emission tomography, in-vitro assay, immunoassays, and liquid scintillation counters. Further, non-medical applications could be advanced biotechnology (such as DNA sequencers), high energy physics experiments, oil well logging, mass spectrometry, environmental measurements, color scanners, space imaging, and low-level light detection. Homeland Security applications include deployment of radiation detectors at fixed locations and at close standoff distances. However, the DoD requirement for field ruggedness and adverse operating environments is unique among these applications. REFERENCES: 1. Glenn Knoll, Radiation Detection and Measurement, 3rd Edition, New York: John Wiley and Son, 2000. 2. Radiation Detection Symposium, University of Michigan, 22-26 May 2006, sponsored by DTRA.
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