Investigation of nuclear material using a compact modified uniformly redundant array gamma camera

We developed a compact gamma camera based on a modified uniformly redundant array coded aperture to investigate the position of a UO2 pellet emitting characteristic X-rays (98.4 keV) and gamma-rays (185.7 keV). Experiments using an only-mask method and an antimask subtractive method were conducted, and the maximum-likelihood expectation maximization algorithm was used for image reconstruction. The images obtained via the antimask subtractive method were compared with those obtained using the only-mask method with regard to the signal-to-noise ratio. The reconstructed images of the antimask subtractive method were superior. The reconstructed images of the characteristic X-rays and the gamma-rays were combined with the obtained image using the optical camera. The combined images showed the precise position of the UO2 pellet. According to the self-absorption ratios of the nuclear material and the minimum number of effective events for image reconstruction, we estimated the minimum detection time depending on the amount of nuclear material. (C) 2018 Korean Nuclear Society, Published by Elsevier Korea LLC.