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    Determination of dosimetric properties of MgO doped natural amethyst samples
    (Pergamon-Elsevier Science Ltd, 2016) Nur, N.; Guckan, V.; Kizilkaya, N.; Depci, T.; Ahmedova, C.; Yucel, A.; Ozdemir, A.
    In this paper, the thermoluminescence (TL) dosimetric characteristics of MgO doped natural amethyst samples (Mg-NA) are presented. The morphologies and chemical structures of the powder form samples were identified using XRD, FTIR, SEM, SEM mapping and EDX. Comparison of the TL intensities showed that 10 wt% Mg-NA was nearly 150 times more sensitive than undoped amethyst and the main dosimetric properties proved that 10 wt% Mg-NA may be a promising phosphor for clinical and radiotherapy purposes. (C) 2016 Elsevier Ltd. All rights reserved.
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    Thermoluminescence properties of Li2B4O7:Cu, B phosphor synthesized using solution combustion technique
    (Pergamon-Elsevier Science Ltd, 2017) Ozdemir, A.; Altunal, V.; Kurt, K.; Depci, T.; Yu, Y.; Lawrence, Y.; Nur, N.
    To determine the effects of various concentrations of the activators copper (Cu) and boron (B) on the thermoluminescence (TL) properties of lithium tetraborate, the phosphor was first synthesized and doped with five different concentrations of copper (0.1-0.005 wt%) using solution combustion method. 0.01 wt% Cu was the concentration which showed the most significant increase in the sensitivity of the phosphor. The second sort of Li2B4O7:Cu material was prepared by adding B (0.001-0.03 wt%) to it. The newly developed copper-boron activated lithium tetraborate (Li2B4O7:Cu, B) material with 0.01 wt% Cu and 0.001 wt% B impurity concentrations was shown to have promise as a TL phosphor. The material formation was examined using powder x-Ray Diffraction (XRD) analysis and Scanning Electron Microscope (SEM) imaging. Fourier Transform Infrared (FT-IR) spectrum of the synthesized polycrystalline powder sample was also recorded. The TL glow curves were analyzed to determine various dosimetric characteristics of the synthesized luminophosphors. The dose response increased in a linear way with the beta-ray exposure between 0.1-20 Gy, a dose range being interested in medical dosimetry. The response with changing photon and electron energy was studied. The rate of decay of the TL signal was investigated both for dark storage and under direct sunlight. Li2B4O7:Cu, B showed no individual variation of response in 9 recycling measurements. The fluorescence spectrum was determined. The kinetic parameters were estimated by different methods and the results discussed. The studied properties of synthesized Li2B4O7:Cu, B were found all favorable for dosimetric purposes.
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    Thermoluminescence properties of non-stoichiometric Li2Si2O5 synthesized from natural amethyst quartz
    (Elsevier Science Bv, 2016) Nur, N.; Guckan, V.; Kizilkaya, N.; Depci, T.; Ahmedova, C.; Ozdemir, A.; Altunal, V.
    In the present study, on the contrary of lots of researches, stoichiometric (s-LD) and non-stoichiometric (n-LD) lithium disilicate polycrystalline were tried to synthesize using easily available and cheap natural amethyst quartz samples collected from Balikesir Dursunbey Turkey as a starting material by the high temperature solid state method. Structure and morphology of s-LD and n-LD were done using XRD, FTIR and SEM, showing the main structure as lithium disilicate for n-LD. The findings showed that n-LD had better crystal structure and gave better TL response, so a detailed investigation on its main dosimetric properties was studied and presented in this paper. The thermoluminescence (TL) glow curve of n-LD consisted of 3 distinguishable peaks and the main peak was stable since TL sensitivity increased only 12% after 2 kGy of high dose exposure. The reusability results showed that TL intensity decreased maximum 21% and 16% for 5 Gy and 50 Gy, respectively after 11 repeated cycles and n-LD had a superlinearity index (g(D)=1.019). The main peak was just 5% faded in 4 weeks. Consequently, n-LD as a phosphor might be used in many fields concerning with the dose range from 0.1 Gy up to 100 Gy. (C) 2016 Elsevier B.V. All rights reserved.
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    Thermoluminescence study of Mn doped lithium tetraborate powder and pellet samples synthesized by solution combustion synthesis
    (Elsevier Science Bv, 2016) Ozdemir, A.; Yegingil, Z.; Nur, N.; Kurt, K.; Tuken, T.; Depci, T.; Tansug, G.
    In this paper, the thermoluminescence (TL) dosimetric characteristics under beta-ray, x-ray and gamma ray excitations of powder and pellet Mn-doped lithium tetraborates (LTB) which were produced by solution combustion synthesis technique were investigated, and the results were compared with that of TLD-100 chips. The chemical composition and morphologies of the obtained LTB and Mn-doped LTB (LTB: Mn) were confirmed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) with EDX. LTB:Mn was studied using luminescence spectroscopy. In addition, the effects of sintering and annealing temperatures and times on the thermoluminescence (TL) properties of LTB:Mn were investigated. The glow curves of powder samples as well as pellet samples exposed to different beta doses exhibited a low temperature peak at about 100 degrees C followed by an intense principal high temperature peak at about 260 degrees C. The kinetic parameters (E, b, s) associated with the prominent glow peaks were estimated using T-m-T-stop, initial rise (IR) and computerized glow curve deconvolution (CGCD) methods. The TL response of integral TL output increased linearly with increasing the dose in the range of 0.1-10 Gy and was followed by a superlinearity up to 100 Gy both for powder and pellet samples using beta-rays. Powder and pellet LTB:Mn were irradiated to a known dose by a linear accelerator with 6 and 18 MV photon beams, 6-15 MeV electron beams and a traceable Cs-137 beam to investigate energy response. Further, TL sensitivity, fading properties and recycling effects related with beta exposure of LTB:Mn phosphor were evaluated and its relative energy response was also compared with that of TLD-100 chips. The comparison of the results showed that the obtained phosphors have good TL dose response with adequate sensitivity and linearity for the measurement of medical doses. (C) 2016 Elsevier B.V. All rights reserved.