It has been known for some time that illumination of lithium fluoride (LiF) thermoluminescent dosimeters, particularly with ultraviolet wavelengths, causes these dosimeters to emit thermoluminescence (TL), similar to that caused by exposure to radiation. However the effect of incandescent light on dosimeters is not well documented. In this study the growth, saturation and spectral dependence of this luminescence is studied for open dosimeter cards illuminated with room incandescent light, and for dosimeters inside their holders exposed to bright sunlight. The results confirm that illumination with room light does give rise to luminescence in unirradiated dosimeters. Light in the ultraviolet is …
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It has been known for some time that illumination of lithium fluoride (LiF) thermoluminescent dosimeters, particularly with ultraviolet wavelengths, causes these dosimeters to emit thermoluminescence (TL), similar to that caused by exposure to radiation. However the effect of incandescent light on dosimeters is not well documented. In this study the growth, saturation and spectral dependence of this luminescence is studied for open dosimeter cards illuminated with room incandescent light, and for dosimeters inside their holders exposed to bright sunlight. The results confirm that illumination with room light does give rise to luminescence in unirradiated dosimeters. Light in the ultraviolet is an order of magnitude more efficient in producing this TL than is longer wave length (red) visible light. The illumination-induced TL saturates at intensities that correspond to TL produced by exposure of about 70 mR of {sup 137}Cs; thus illumination clearly can give rise to false radiation exposure reports. Moreover it was fund that the dosimeter holder allows enough light to enter so that exposure of dosimeters to bright sunlight will activate some of the chips of the dosimeter cards in a fashion identical to that of room light. The glow curves produced by light are broader than those produced by gamma irradiation and a series of experiments have confirmed that the light induced TL comes from the Teflon sheets holding the LiF dosimeters, rather than the LiF chips themselves. 13 refs., 5 figs., 2 tabs.
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Sonder, E.; Ahmed, A. B.; McMahan, K. L.; Colwell, D. S. & Smith, P. R.The effect of visible light on Harshaw Model 8801 thermoluminescent dosimeters,
report,
September 1, 1990;
Tennessee.
(https://digital.library.unt.edu/ark:/67531/metadc1104843/:
accessed July 16, 2024),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.