Influence of Irradiation Rate on the Production of F Centers in LiF (TLD Grade)

Optically polished samples of extruded plaques of LiF (TLD grade) were given 60Co gamma-ray exposures ranging from about 35 000–450 000 R, at exposure rates between about 1.5×103 and 5×106 R/h. Over this range of exposures and exposure rates, the resulting absorption in the F band was found to be independent of exposure rate, and to increase with exposure, even for exposures for which the thermoluminescence exhibited saturation effects. After thermoluminescence readout at about 235°C, practically all the absorption in the F band created by the 60Co gamma-ray exposures had disappeared. These results are compatible with the dominant role given F centers in some of the current models for the thermoluminescence process in LiF (TLD grade).