Study of photostimulated- and thermo-luminescence characteristics for detecting irradiated kiwifruit

摘要

Photostimulated luminescence (PSL) and thermo-luminescence (TL) analyses were conducted to detect irradiated kiwifruits. Samples were irradiated with Co-60 gamma-rays at 0-2 kGy. The freeze-dried kiwifruit peel showed 309 photon counts (PCs) for nonirradiated samples that accounted for less than the lower threshold value (700 counts/60 s, negative) and above 9306 PCs for 1 and 2 kGy-irradiated samples, which was higher than the upper threshold value (5000 counts/60 s, positive). However, PSL signals of irradiated samples remarkably decreased after 6 weeks of storage. The TL measurement using minerals isolated from the whole kiwifruit surface revealed a glow curve (TL1) with a low intensity at 200-300 degrees C in nonirradiated samples but with a higher intensity at around 180 degrees C in irradiated samples at 1 kGy or more. The TL ratios, integrated areas of TL1/TL2 that was measured after 1 kGy re-irradiation for the TL1-tested minerals, were less than 0.1 in nonirradiated samples and higher than 0.1 in irradiated ones and could verify TL1 results. The inorganic dust minerals used were mainly composed of feldspar and quartz.