Basic investigations on thermoluminescent lithium fluorides

LiF materials for application in thermoluminescence (TL) dosimetry are produced in France (CEA) as well as in Germany (PTB). Although both materials differ markedly in the physico-chemical way of production the basic dosimetric and physical properties are very similar. This is demonstrated by TL glowcurves, TL sensitivity, supralinearity and optical absorption and leads to the conclusion that the lattice defects (electron traps and activators) necessary for the TL effect are identic for materials of both origins. Electron traps creating the TL main glowpeak are introduced by the Mg dopant. A precise analysis of optical absorption spectra leads to the assumption of Z2 centers being produced by irradiation in a two step process. This model explains radiation sensitization as well as the necessity for a thermal treatment before the re-use of LiF-TL dosimeters