engleski

Dosimetric Characteristics of Lithium Borate Solid TL Detectors with Different Dopants

Although the lithium borate thermoluminescent (TL) detectors are known more than 30 years, the significant improvements were made in past several years by the selection of appropriate activators and preparing the several new types of these detectors in the form of sintered pellets in the Institute of Nuclear Sciences, Vinča, Serbia and Montenegro. In this work the characteristics of Li2B4O7:Cu, In, Li2B4O7:Cu, In, Ag and Li2B4O7:Cu, Ag, P are compared with the characteristics of the well known type, LiF:Mg, Ti detector (TLD-100). The following properties were investigated for the proposed evaluation parameters: the glow curve characteristics, batch homogeneity, relative sensitivity, detection threshold, fading, linearity in the wide dose range and reproducibility of the response. Also, the energy dependence for medium and low energy X-rays was determined: TLDs previously calibrated with 137Cs gamma rays, were simultaneously irradiated with X-ray beams in the range of effective energies between 33 and 116 keV. Irradiations were performed: a) “ In air” and measured energy responses normalised to those to 137Cs photons were compared with calculated data. The energy dependence obtained in this way is the inherent characteristic of the TL detector itself. b) On the 30 cm  30 cm  15 cm water phantom with PMMA walls (ISO phantom). Measured energy responses were compared with the calculated data for Hp(10) values and the energy dependence in terms of Hp(10) values was obtained. The results show that all types of TL detectors possess very good “ tissue equivalency” in investigated range of photon energies and their characteristics are discussed for various possible applications.

Thermoluminescence dosimetry; Lithium borate; Glow curve; Energy dependence

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