Coded-aperture based stereo gamma-ray imager for near field 3-D localization

Abstract

Since the Fukushima nuclear disaster, the use of gamma-ray imagers to explore contaminated areas has increased substantially. Contaminated area identification and radionuclide determination techniques are essential for creating detailed radioactive contamination maps. These maps can contribute to reducing the exposure of radiation workers to ensure efficient decontamination during the decommissioning of nuclear power plants. In this study, a stereo gamma-ray imager was developed by arranging two EPSILON-G gamma-ray camera modules in parallel to estimate the depth of a gamma-ray source. This camera module uses MURAs coded-aperture for the image reconstruction of gamma-ray sources. MCNPX-Polimi simulations determined the optimal distance between the camera modules (d) to be 26 cm. For depth estimation, the stereo gamma-ray imager utilizes triangulation, and experimental verification confirmed the accuracy, with a maximum error of approximately 3.75 %, at both the center and at randomly selected points of the stereo gamma-ray imager. In addition, the depth of two gamma-ray sources was estimated simultaneously, with a maximum depth estimation error of approximately 8.31 %. The results demonstrate the feasibility and accuracy of using a stereo gamma-ray imager for estimating the 3-D position of a gamma-ray source and contribute to improving the safety and efficiency of nuclear decontamination and disposal processes.

Keywords

• 3D positional information
• Depth
• Coded-aperture
• Stereo camera
• Gamma ray