Capacitive Output Radiation Detector

In support of its efforts in nuclear nonproliferation, the DOE is seeking new, large-size radiation detectors, suitable for industrial-scale production, with improved energy resolution. Semiconductor radiation detectors ¿ in particular, cadmium zinc telluride detectors ¿ are known for their fine energy resolution. However, the fabrication of large-volume detectors (up to 100 cubic centimeters) from this material presents a technical challenge due to the difficulties of growing large crystals and efficiently collecting radiation-generated charge carriers. To overcome these problems, this project will develop a novel capacitive output radiation detector, utilizing electrical polarization of cadmium zinc telluride microcrystals (grains) in a nonconductive, flexible, low-density polymer matrix. Unlike detectors with a single crystal, the proposed detector will utilize capacitive readout, which detects changes in the radiation-induced electrical polarization of the composite material. The use of microcrystals instead of large single crystals will allow for the fabrication of large-volume detectors. Conventional web technology will be used to assemble laminated rolls of composite material from relatively inexpensive microcrystals in a polymer matrix. Phase I will fabricate the detector prototype and demonstrate an energy resolution of ~1% FWHM at 0.662 Megaelectron volts 137Cs emission. Commercial Applications and other Benefits as described by the awardee: The technology should have a significant impact in proliferation detection and security applications. Also, a significant commercial market niche should exist in nuclear medicine, from miniature intraoperative surgical gamma probes to pixelized imaging devices for rapid intraoperative radioactivity tracing. Finally, systems based on the device could find use in the nuclear power industry for environmental monitoring and industrial safety ¿ the low cost of these sensors would permit large areas to be monitored with a net of multiple probes.