A Scanning Coded-Aperture Imager for Nuclear and Radiological Materials Characterization

Steven Brown - H3D, Inc.
James Mason - H3D Inc.
Hao Yang - H3D, Inc.
Reid Sobota - H3D, Inc.
Michael Streicher - H3D, Inc.
Willy Kaye - H3D, Inc.

We have developed a high-resolution coded-aperture imager for quantitative imaging of x-ray and low-energy gamma-ray sources. The 25-lb prototype contains ~38 cm3 pixelated-CZT detectors surrounded by a cylindrical coded mask. The URA-patterned-tungsten mask scans the object during a measurement, encoding the source distribution as a function of time. Scanning motion has been shown to significantly increase image SNR, improving quantitative accuracy compared to a static mask. Gamma events are streamed to a laptop with a dedicated GPU that generates images vs energy in real time. Reconstructed images have < 2 -degree angular resolution with energy resolution about 1% FWHM at 662 keV. This paper describes the novel device and shows measurements of check sources as well as uranium and plutonium test objects.