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Widespread use of LiF in personnel dosimetry has generated a requirement that material be selected on a continuing basis which has the same sensitivity as that already deployed. The preservation of TL standards over a long period requires that the standard be reusable without change. Studies have been made to determine the effect ofhandling, heating, cleaning and exposure to radiation on the lifetime of solid LiF dosimeters.Handling with tweezers has been found to produce abrasions and to change the sensitivity of the dosimeters by as much as 0.1 % for each time they are grasped by metal tweezers. The use of vacuum handling tools avoids such changes. While significant changes in sensitivity occur upon annealing, the long term effects ofmultiple readout cycles do not damage the dosimeter. Dosimeters have been subjected to 1200 readout cycles without change in sensitivity. Based on these results, a system of standardization of materials has been devised which should provide for maintenance of a TL light standard for many years.

No abstract