The 3-D elemental imaging method research based D elemental imaging method research based on photoneutron analysis on photoneutron analysis on photoneutron analysis on photoneutron analysis

摘要

A photoneutron based analysis system, which is composed of a 7 MeV LINAC, a 2.6 kg beryllium photoneutron convertor and a NaI(Tl) detector array, has been setup to register the 2-dimensional elemental distributions of the inspected materials. 2-dimensional images of 4 elements, hydrogen, nitrogen, chlorine and iron, could be acquired simultaneously in once scanning to indicate the potential existence of concealed contrabands. But the overlap between different materials of the elemental distribution may disturb the identification of contrabands because their elemental concentrations will be mixed with innocent materials. To remove the overlap effect of different materials, 3-dimensional elemental imaging technique is researched in this paper. By using two opposite-placed detector arrays of 8 NaI(Tl) detectors respectively, two images for 4 elements are measured. An algorithm is developed to fuse the two images together to form a 3-dimensional image for each element by comparing the count rates and footprints of the element measured by two detector arrays. The preliminary result shows that the spatial resolution of hydrogen, nitrogen, chlorine and iron could be 20 cm * 40 cm * 20 cm. The overlap of different materials then could be removed and the capability of contrabands identification could be enhanced.