Browsing by Subject "Activation analysis"

Now showing 1 - 7 of 7
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    Modification of the radial beam port of ITU TRIGA Mark II research reactor for BNCT applications
    (Elsevier Ltd, 2015) Akan Z.; Türkmen M.; Çakir T.; Reyhancan T.A.; Çolak T.; Okka M.; Kiziltaş S.
    This paper aims to describe the modification of the radial beam port of ITU (Istanbul Technical University) TRIGA Mark II research reactor for BNCT applications. Radial beam port is modified with Polyethylene and Cerrobend collimators. Neutron flux values are measured by neutron activation analysis (Au-Cd foils). Experimental results are verified with Monte Carlo results. The results of neutron/photon spectrum, thermal/epithermal neutron flux, fast group photon fluence and change of the neutron fluxes with the beam port length are presented. © 2015 Elsevier Ltd.
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    Thermoluminescence behavior of Sm3+ activated ZnB2O4 phosphors synthesized using low temperature chemical synthesis method
    (Elsevier B.V., 2018) Bulcar K.; Dogan T.; Akça S.; Yüksel M.; Ayvacikli M.; Karabulut Y.; Kucuk N.; Canimoglu A.; Can N.; Topaksu M.
    This study is mainly centered on thermoluminescence (TL) behavior under beta excitation at room temperature (RT) of Sm3+ activated ZnB2O4 phosphors synthesized by low temperature chemical synthesis method. The prepared phosphors were characterized by the X-ray powder diffraction (XRD) method. The effects of dopant concentration, beta radiation dose (0.115–69 Gy) and heating rate (0.5–10 °C/s) on TL intensity of Sm3+ doped ZnB2O4 phosphors and reproducibility are investigated using a lexsyg smart TL/OSL reader system. The activation energy values, E obtained from the analysis of the TL glow curve were calculated with initial rise (IR) method and peak shape (PS) method over the deconvoluted glow curves. The Ea–Tstop and CGCD methods indicated that the glow curve of this phosphor is the superposition of at least six components, which were called to as P1–P6, in the temperature range between RT and 400 °C. The results reveal that 2% Sm3+ doped ZnB2O4 gives optimum TL response, the relative intensity of the glow peak increases linearly with increase of beta dose and, the peaks of TL glow curves shift towards the higher temperature side with increase in heating rate as the total area under the glow peak remains the same. The maximum variation of reproducibility for ten successive irradiation cycles of 20.7 Gy is less than 3% from the average value and the sample doped 2% Sm3+ shows a good stability for the reusability. Additionally, the results obtained from IR and PS methods indicates that the complex glow curve is composed of six distinguishable peaks. © 2018 Elsevier B.V.
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    Thermoluminescence study and evaluation of trapping parameters of samarium doped barium silicate phosphor
    (Taylor and Francis Ltd., 2021) Alajlani Y.; Oglakci M.; Kaynar U.H.; Ayvacikli M.; Portakal-Uçar Z.G.; Topaksu M.; Can N.
    We report the detailed analysis of thermoluminescence (TL) glow curves and the evaluation of kinetic parameters of Sm3+-incorporated BaSi2O5.The effect of various heating rates on TL kinetics and glow peak temperatures of Sm3+-doped BaSi2O5 phosphors exposed to beta particle irradiation at room temperature are investigated. The glow curve of the phosphor exposed to β-irradiation consists of two main peaks with maxima at about 91°C and 193°C and exhibits good linearity between 1 and 10 Gy. The activation energies and frequency factors of trap centers involved in the TL emission were calculated from the TL glow curve of the sample by means of variable heating rate (VHR), repeated initial rise (RIR), and computerized glow-curve deconvolution (CGCD). Analysis of the main dosimetric peak techniques indicate that activation energies (E) and pre-exponential factor (s) vary between 0.93 and 1.72 eV, 1010 and 1013 s−1. It is found that the temperature of the glow peaks shifts toward the higher temperatures and the TL intensity smoothly decreases as the heating rate increases. The behavior of the TL intensities and glow peak temperatures as a function of the heating rate are discussed with regards to thermal quenching. © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of The Korean Ceramic Society and The Ceramic Society of Japan.
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    Thermoluminescence glow curve analysis and evaluation of trapping parameters of dysprosium doped lanthanum calcium borate La2CaB10O19
    (Elsevier B.V., 2021) Bulcar K.; Oglakci M.; Kaynar U.H.; Ayvacikli M.; Souadi G.; Topaksu M.; Can N.
    The present work elucidates thermoluminescence study of Dy activated lanthanum calcium borate (La2CaB10O19) phosphors and determination of trapping parameters. Two glow curves located at 132 and 295 °C were observed and showed a linear TL response. The kinetic parameters of the glow peaks were evaluated using variable heating rate, repeated initial rise method and Computerized Glow Curve Deconvolution. Analysis of the main dosimetric peaks reveals that the values of the activation energy and pre-exponential factor are found to be 0.78–1.145 eV and 8.59 × 109–8.44 × 1011 s−1, respectively. The sample doped with 1% Dy3+ exhibits a good stability for the reusability. Besides, the found results indicate that the temperature maximum shifts to the higher temperature side as the heating rate increases. Contrary to previously expressed theoretical expectations, anomalous heating rate dependence was observed in Dy3+ doped La2CaB10O19 sample and a semi-localized transition model explaining the anomalous heating rate effect was employed. © 2020 Elsevier B.V.
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    Thermoluminescence glow curve analysis and kinetic parameters of Dy-doped BaSi2O5 phosphor
    (Editorial Office of Chinese Rare Earths, 2022) Alajlani Y.; Can N.
    In this paper, Dy3+ incorporated BaSi2O5 phosphors were synthesized by gel combustion method and characterized by X-ray diffraction (XRD). The effects of various heating rates on thermoluminescence (TL) kinetics and glow peak temperatures of Dy3+ incorporated BaSi2O5 phosphors exposed to β irradiation at room temperature were investigated. The glow curves of the phosphor exposed to β-irradiation (0.1–100 Gy) consist of four main peaks located at 87, 130, 271, and 327 °C and exhibit a good linearity between 0.1 and 100 Gy. Three experimental techniques including variable heating rate (VHR), repeated initial rise (RIR), peak shape (PS) and computerized glow curve deconvolution (CGCD) were employed to determine TL kinetic parameters. Our findings indicate that the TL glow peaks of the phosphor obey first-order kinetics. Analysis of the main dosimetric peaks through the techniques mentioned above indicates that activation energies (E) and pre-exponential factor (s) are in the range of 0.80–1.50 eV and 1.15 × 108–3.28 × 1013 s−1. Additionally, it is found that the temperature of the glow peaks shifts toward the higher temperatures and the TL intensity smoothly decreases as the heating rate increases. The effect on the TL intensities and glow peak temperatures of the heating rate is discussed in terms of thermal quenching. © 2020 Chinese Society of Rare Earths
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    Beta irradiation-induced thermoluminescence: Glow curve analysis and kinetic parameters in combustion-synthesized undoped Ca4YO(BO3)3
    (Elsevier Ltd, 2024) Madkhli A.Y.; Jabali D.A.; Souadi G.; Sonsuz M.; Kaynar U.H.; Akça-Özalp S.; Ayvacikli M.; Madkhali O.; Topaksu M.; Can N.
    This study examines the thermoluminescent (TL) properties of undoped Ca4YO(BO3)3 phosphor, focusing on how it behaves under a variety of experimental conditions. The IRSL-TL 565 nm was chosen as the appropriate detection filter among various optical detection filter combinations. During the preheating trials conducted at a rate of 2 °C/s, the TL peak exhibited increased intensity, particularly around 200 °C. The experimental outcomes demonstrated a reliable linear relationship (R2 = 0.996 and b = 1.015) in the dose response of undoped preheated Ca4YO(BO3)3 within the range of 1–200 Gy. The investigation encompasses a range of techniques, including the TM-Tstop method, computerized glow curve deconvolution (CGCD) analysis, and theoretical modelling. The application of the TM-Tstop method to samples irradiated with a 5 Gy dose revealed distinct zones on the TM versus Tstop diagram, signifying the presence of at least two discernible components within the TL glow curve, specifically, a single general order kinetics peak and a continuous distribution. The analysis of activation energy versus preheated temperature exhibited a stepwise curve, indicating five trap levels with depths ranging between 1.13 eV and 1.40 eV. The CGCD method also revealed the superposition of at least five distinct TL glow peaks. It was observed that their activation energies were consistent with the Tm-Tstop experiment. Furthermore, the low Figure of Merit (FOM) value of 1.18% indicates high reliability in the goodness-of-fit measure. These findings affirm the reliability and effectiveness of the employed methods in characterizing the TL properties of the Ca4YO(BO3)3 phosphor under investigation. Theoretical models, including the semi-localized transition model, were introduced to explain anomalous observations in TL glow peak intensities and heating rate patterns. While providing a conceptual framework, these models may require adjustments to accurately capture the specific characteristics uncovered through CGCD analysis. As a potential application, the study suggests that the characterized TL properties of Ca4YO(BO3)3 phosphor could be utilized in dosimetric applications, such as radiation dose measurements, owing to its reliable linear response within a broad dose range. © 2024 Elsevier Ltd
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    Synthesis and thermoluminescence behavior of novel Sm3+ doped YCa4O(BO3)3 under beta irradiation
    (Elsevier Ltd, 2024) Altowyan A.S.; Sonsuz M.; Kaynar U.H.; Hakami J.; Portakal-Uçar Z.G.; Ayvacikli M.; Topaksu M.; Can N.
    This study investigates the luminescent properties and dosimetric potential of YCa4O(BO3)3:0.5%Sm3+ phosphor synthesized via the combustion method. Dose-response investigations unveil a noteworthy linear increment in thermoluminescence (TL) intensity, emphasizing a remarkable linearity spanning a broad dose range from 0.1 to 300 Gy. Unusual heating rate effects are explored, revealing a shift in TL glow curve peak temperature (i.e 200 °C) towards higher temperatures with increasing heating rate. Speculative models, including Kinetic Trapping Effect, Thermal Quenching Compensation, and Defect Activation Energy Changes, are proposed. The study employs the Tmax-Tstop method to identify characterize glow curve peaks, and the Initial Rise method for the low-temperature segment analysis, revealing seven distinct trap levels at various depths within the bandgap. Glow curve deconvolution using the Complex Glow Curve Deconvolution (CGCD) method delineates a multi-peak structure, offering valuable insights into luminescent mechanisms. The model exhibits a Figure of Merit (FOM) of 1.71%, within an acceptable range, affirming its reliability. However, interpretation of the activation energy and frequency factor values suggests intricate site processes, necessitating a nuanced analysis to understand the material's luminescent characteristics. The YCa4O(BO3)3:0.5%Sm3+ phosphor demonstrates promising characteristics for precise dosimetry, with linear dose response, absence of saturation effects, and intriguing heating rate behavior. © 2024 Elsevier Ltd and Techna Group S.r.l.