PREPARATION OF SINGLE-CRYSTAL LIF TLD AND ITS CHARACTERISTICS

Single crystals of thermoluminescence lithium fluoride dosimeter (LiF TLD) with copper (0.05 mol%), magnesium (0.2 mol%) and phosphorus (0.1 approximately 0.5 mol%) as activators were produced for the purpose of eliminating the self-absorption of thermoluminescent light. TLD elements of the size 4 X 4 x 2 mm3 were cut from the single crystal produced. Among the activators phosphorus was reported to be the most effective for the thermoluminescence. For single crystal formation the threshold of the doping amount was observed even in the chemical form of Li3PO4. Results obtained are that the optimum amount of phosphorus activator is 0.5 mol% and the optimum bottom angle of the graphite crucible for single crystal formation is nearly 60-degrees. For practical use production of large volume single crystal (60 mmphi x 90 mm) was examined. Two single crystals were successfully produced and 474 usable TLD chips were obtained from the both crystals. This suggests that the single crystal LiF TLD may replace the TLD's currently used.