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Thermoluminescence (TL) measurement is a means of discriminating between irradiated and non-irradiated food carrying small amounts of sand or dust. Silicate minerals are isolated and purified, and their radiation-induced luminescence is measured. When ‘pure quartz’ was studied by TL analysis, glow curves of different shape, position and intensity were obtained from various sources of radiation having different dose rates and beam energies. To study the effect of dose rate, ‘pure quartz’ was exposed to60Co-γ-rays from two sources at various dose rates (∼ 0.060 Gy/s or ∼ 0.0025 Gy/s). In addition, quartz powder and quartz sand of less purity were examined. Both total dose and dose rate influenced the TL behaviour. Only very slight differences among the TL glow curves of ‘pure quartz’ have been found at various dose rates of a dose of 0.2 kGy. At 1.0 kGy, however, greater differences in shape, position and intensity appeared. At 5.0 kGy, the differences in shape and position, but not in intensity, decreased. Glow curves of quartz powder, too, showed—though less pronounced—differences in shape and intensity at various dose rates. Quartz sand failed to produce such differences in its glow curves at different dose rates. |
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