Plastic scintillators utilizing iridium complex fluorophores offer substantial improvements in light yield, and their light yield is not significantly quenched in compositions with bismuth metalorganic loading, at a loading level of 21 wt% bismuth metal. This new bismuth plastic (Ir-Bi-Plastic) offers improved detection efficiency over commercial plastic scintillators. One application for Ir-Bi-Plastic is in low-cost, portable, and durable dual-particle imaging (DPI) systems supporting nuclear safety, security, and safeguards. However, new materials must undergo investigation using industry standards to quantify their capabilities. In this work, an Ir-Bi-Plastic was experimentally evaluated as a small, pixelated radiographic array in a fast neutron environment, with individual pixel dimensions of 2×2×19 mm. For comparison, identical evaluations were conducted for two similarly sized arrays made from EJ-200 and EJ-256. A separate Ir-Bi-Plastic array with 5×5×20 mm pixels was also evaluated. ASTM methods were leveraged to determine the modulation transfer function and spatial resolution for each array. Edge response measurements of a 2-in thick tungsten block were recorded by pressure coupling all four arrays to a commercial a-Si digital radiographic panel. Experimental results were then compared for all four arrays, and the results demonstrated that the Ir-Bi-Plastic outperforms similar arrays made from EJ-200 and EJ-256 (5 wt% Pb). These findings suggest that DPI systems utilizing Ir-Bi-Plastic hold promise for continued development over older, more traditional, alternatives.
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