High-level photon dosimetry with thermoluminescent materials

For very high dose levels in the 104 to 108 rad range, for example in chemistry and technology, food-processing, radiation sterilization, material testing etc., chemical dose measuring techniques, such as the Fricke-system, the ceric-sulfate-system, the ferric-cupric-system, the oxalic-system or organic dyes in the form of liquid solutions are being used with success beside calorimetric methods. Those techniques require much effort and also much attention for obtaining good results and are too expensive for routine measurements, where hundreds or even thousands of single measurements have to be performed. A less expensive method may be found in the application of the thermally stimulated emission of luminescence light (thermoluminescence, TL) of certain materials (phosphors) after exposure to radiation or in related phenomena. Various phosphors were investigated for this purpose in the past, like CaF2:Mn, LiF:Mg, Ti and Li2B4O7:Mn, all materials with dynamic ranges extending to a dose of about 105 rad. These materials are described in this paper with respect to their applicability for high dose measurements as well as phosphors like metaphosphate glass, BeO, Al2O3, CaSO4:Dy, CaSO4:Tm. The result of the survey is, that, if price is the governing factor, it seems that for many applications Li2B4O7:Mn is the phosphor of choice, which, if home-produced, can be used as a throwaway material. (orig.)