Development of a new highly sensitive LiF thermoluminescence dosimeter and its applications

New highly sensitive phosphors of LiF-TLD were prepared for use in a low dose measurement. The phosphor was doped with three kinds of impurities which are Cu, Mg, and P, Si or B ion. Sensitivity of these phosphors doped with the third dopant was higher than that of TLD-600 LiF and, especially, the sensitivity of LiF(Mg, Cu, P) phosphor was about 23 times that of TLD-600 LiF, and nearly equal to Mg2SiO4(Tb) and CaSO4(Tm) phosphors. The thermoluminescence response to the dose increases sublinearly in the dose range of 1000 rad and more, but increases linearly in the dose range of 1000 rad and less. Tribothermoluminescence intensity increases with the vibrating period, and the maximum intensity is equivalent to about 300 mrad, but when the irradiated phosphor was heated up to about 270°C or less for evaluating the dose, the dose evaluation was scarcely affected. Application of this new phosphor to environmental radiation dosimeter and medical radiation dosimeter is discussed.