Title: Demonstration of a novel stand-off 3D gamma-ray imaging technique
Citation: 50th Annual Meeting of the Institute of Nuclear Materials Management
Publisher: INMM - Institute of Nuclear Materials Management
Publication Year: 2009
JRC N°: JRC51621
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC51621
Type: Articles in periodicals and books
Abstract: The Compact Compton Imagers CCI-1 and CCI-2 are two successive gamma-ray imaging prototypes developed by our group. Both systems use the Compton camera concept for imaging, and are based on position sensitive, double sided segmented (DSSD) planar HPGe and Si(Li) detectors. Whereas each electrode of the Ge detectors is segmented in 37 strips, 2mm pitch size, each electrode of the Si(Li) detectors is segmented in 32 strips, 2 mm pitch size. Both imaging systems provide panoramic images of extended sources in a 4-pi field of view for modest intensity sources at distances from 3 to 400 cm with an angular resolution as good as 2 degrees. An average energy resolution of 2 keV per channel enables these instruments to accurately identify radioisotopes. The cameras are sensitive to gamma-ray photons of energies between 150 keV to several MeV. We report on measurements using these imagers to create 3D maps of extended gamma-ray sources distributed in the environment in the medium to far-field distances. For increased image contrast and accuracy, range data from a LIDAR scanner was merged into the 3D gamma-ray image reconstruction process. This integration not only allows for accurate imaging of extended sources in a large range of distances, but also helps the operator to unambiguously identify the objects containing the radioactive materials. By comparison, a simple projection of a gamma-ray image onto a visual picture can often lead to ambiguous interpretations. The experimental technique will be described along with the data analysis and image reconstruction utilized in the process. The goal of this development work was to demonstrate the potential gain in monitoring installations and nuclear materials simultaneously using a gamma-ray imaging and a LIDAR system. A future dedicated system developed on this concept can potentially increase the sensitivity and automation level for inspection and monitoring of plants processing nuclear materials. Of special interest is the measurement of material hold-up in hard to reach places.
JRC Directorate:Space, Security and Migration

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