Thermoluminescence properties of fluorescent materials used in commercial lamps

The dosimetric properties of eight different fluorescent materials (FM) used in production of commercial fluorescent lamps were studied by thermoluminescence (TL). Taking into account the criteria for TL phosphors to be useful for radiation dosimetry, radiation sensitivity, thermal stability, shape of the glow curves, and effect of incandescence, UV and daylight on irradiated and non irradiated material were investigated. It was observed that most of the material can be used for radiation doses from 10 mu Gy to 1 kGy. The radiation induced signal is found to be thermally very stable. The calcium halophosphates doped with Sb and Sb:Mn having a similar mineral phase as teeth and bone may be used for dosimetry in radiation therapy and diagnostics. The strontium borophosphates and barium magnesium aluminate doped with Eu were found to be sensitive to light and may be used in solar energy research

ESR AND TL AGE-DETERMINATION OF CALICHE NODULES

Feasibility of dating caliche nodules by ESR and TL is investigated. For both methods the properties of the dating signal are described. Chemical composition as well as TL glow curves of caliches originating from different localities exhibit some differences. Due to the complexity of the TL glow curves, some samples required a special post-annealing procedure in order to resolve the main TL peak for age determination. Typical ESR calcite signals do not exist in caliche, therefore usefulness of the g = 2.0040 ESR signal is studied. The results of TL and ESR ages are found to be compatible except for two samples. Possible causes of the discrepancy in these samples are discussed. It is shown that, with proper treatment of the radiation-induced signals, it was possible to date caliche formations older than 350 ka, which is not achieveable with other methods like uranium series disequilibrium and/or radiocarbon dating