Characterization of thermoluminescent properties of Seydişehir alumina and investigation of properties of dose response

Thermoluminescence dosimeters (TLDs) is a passive dose measurement method used for the supervision, quality control and calibration during radiation dose measurements. Nowadays TLDs, containing alumina, are largely used and investigated due to high sensitivity, physical and chemical stability, and re-usefulness. In this work, employability of Seydişehir alumina as a thermoluminescence material, found and produced abundantly in our country, was investigated. For this aim, fundamental trap parameters which establish thermoluminescence properties of Seydişehir alumina, have been determined and its characterization of dose response and fading have been measured. In the first section of this study literature investigation was done and results were represented about alumina as a TLD material. In the second section mathematical models to explain thermoluminescence emission were investigated in detail, experimental methods to calculate thermoluminencent trap parameters which establish thermoluminescent emitting and their mathematical fundamentals were described. In the third experimental section, firstly granule sizes of Seydişehir alumina were measured and for the experiments 40 mm < h < 60mm granule sizes were chosen. The crystal structure of the chosen material was investigated and was calsined in order to change into alpha phase. Chemical composition was determined sensitively by using XRF and ICP spectroscopy. In the thermoluminencent measurements Harshaw Model 3500 Manual TLD Reader system and 90Sr - 90Y ß - radiation source were used. In this study it is demonstrated that powder samples could be reused safely after a simple annealing process. Powder samples were irradiated at many different ß - radiation doses 0,07 Gy to 1282,79 Gy and trap parameters were calculated by using many different methods such as initial rises, various heating rates, isothermal decay, peak shape, computerized glow curve deconvolution. It has been shown that its glow curve is basic and calculated trap parameters are convenient to literature. Dose response of Seydişehir alumina was investigated by using the peak height and the peak area under the glow curve. It has been shown that between 0,07 Gy to 160,34 Gy dose range it has linear dose response and up to 1282,79 Gy dose range it does not reach saturation. Fading properties were determined for 6 hours, 1, 7, 14, 21, 30 and 60 days and after 60 days of waiting period fading was calculated as % 65 ± 1. On the other hand, at the end of 30 days waiting period the peak?s height, found in the high temperature region, increased by about % 2158 and it has been asserted that fading occur by means of tunneling.Keywords: Thermoluminescence, alumina, dose response, characterization, trap parameters