Lithium fluoride (LiF) thermoluminescent powder doped with Mg, Cu, Na, and Si as activators was prepared. The dopant concentrations were varied over the wide ranges as follows: Mg (0.05 - 1.0 mol$\%$), Cu (0.01 - 1.0 mol$\%$), Na,Si (0.3 - 2.4 mol$\%$). The results indicated that the Mg and Cu activators are crucial dopants in the LiF:Mg,Cu,Na,Si phosphors. The LiF:Cu,Na,Si samples without Mg exhibit a peak at low temperature in the thermoluminescent glow curve and in the absence of Cu, the LiF:Mg,Na,Si samples exhibit a peak at high temperature. The Na,Si were effective dopants in producing the high intensity of the low-temperature peaks and the main peak. The emission spectrum measurements at each peak temperature of the TL glow curve were carried out for the LiF:Mg,Cu,Na,Si sample. The results showed that with increasing the peak temperature of the TL glow curve, the peak wavelength is generally shifted towards the low wavelength side.
