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- Yüksek Lisans TeziYalnız künye2026YBCO süperiletkenlerinde radyasyon soğurma parametreleri ile termokimyasal reaksiyon verimliliği arasında yarı-ampirik bir enerji bağıntı modeli önerisi
Gilles Luh Nsangou
Bu tez çalışmasında, YBCO süperiletkenlerinde radyasyon soğurma parametreleri ile termokimyasal reaksiyon verimliliği arasındaki ilişki yarı-ampirik bir enerji bağıntı modeli çerçevesinde incelenmiştir. Çalışmanın ana odağı Y123 ve Y358 fazlarıdır. Tez kapsamında yeni bir deneysel üretim yapılmamış; daha önce yayımlanmış yapısal, termokimyasal, stokiyometrik ve radyasyon soğurma verileri kullanılarak veri-temelli bir modelleme yaklaşımı geliştirilmiştir. Diferansiyel termal analiz verilerinden elde edilen Energy-Reaction Index (ERI) değerleri Y123 için 1,84, Y358 için 1,29 olarak değerlendirilmiş ve Y123 fazının termokimyasal reaksiyon etkinliğinin daha yüksek olduğu görülmüştür. Modelde temel fiziksel düzeltme olarak kütle soğurma cevabı ile lineer/yapısal zırhlama cevabı ayrı kanallar halinde tanımlanmıştır. Kütle soğurma oranı yoğunluktan bağımsız enerji-bileşim kanalını, lineer zırhlama oranı ise bulk yoğunlukla düzeltilmiş makroskopik cevabı temsil eder. İçsel kalite göstergesi referansa normalize edilerek modelin sınır koşulu korunmuştur. Düşük enerji bölgesindeki Y358 avantajı, teorik üstünlük olarak değil deneysel veriler ve gerçek numune etkileri bağlamında yorumlanmıştır. Ho katkılı Y358 serisi, iki kanallı modeli destekleyen tamamlayıcı bir örnek olarak kullanılmıştır. Sonuç olarak bu tez, YBCO süperiletkenleri için sentez-termokimya-yapı-radyasyon bağlantısını fiziksel olarak ayrıştırılmış ve kalibre edilebilir bir yarı-ampirik çerçevede sunmaktadır.
- MakaleYalnız künye2026Scopus SJRQ2Influence of holmium substitution on structural characteristics and radiation shielding parameters of YBCO (358) superconducting ceramics
Düzgün, İbrahim; Kaya, Selim; Gül, Osman
This study reports on the structural characterization, radiation shielding assessment, and magnetic-field response of holmium-substituted Y3-xHoxBa5Cu8O18+δ superconducting ceramics synthesized by the conventional solid-state reaction route. X-ray diffraction measurements on five compositions (x = 0, 0.75, 1.5, 2.25, 3) supported the formation of a dominant orthorhombic Y358-type matrix across the substitution range. Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS) revealed a progressive microstructural evolution with increasing Ho content, including SEM–BEC/EDS-detectable Ho-rich inclusions consistent with Ho2BaCuO5-type secondary particles at higher substitution levels. XCOM-based mass attenuation coefficients, half-value layer, mean free path, effective atomic number, radiation protection efficiency, gamma-ray kerma coefficients, and fast-neutron removal cross-sections were calculated for all five compositions over 50–2000 keV. EGS4 Monte Carlo simulations independently verified the XCOM results for three representative compositions (x = 0, 1.5, and 3). Ho-containing specimens exhibited a significant enhancement in photon absorption near 60 keV, associated with the increased photoelectric contribution of holmium in the vicinity of its K-absorption edge. Among the full five-composition series, the x = 2.25 specimen (ρ = 5.531 g cm−3) exhibited the best calculated shielding performance across the full energy range, owing to its highest bulk density combined with substantial Ho incorporation. The x = 1.5 specimen provided the most balanced calculated radiation-attenuation and hysteretic magnetic response among the three representative compositions examined by EGS4 and M–H measurements at 20 K, retaining approximately 93% of the reference M–H hysteresis area while full substitution reduces it by roughly 67%. These findings establish a multi-parametric reference dataset for Ho-substituted Y358 ceramics and demonstrate the promise of rare-earth-engineered superconducting ceramics as multifunctional materials in radiation-intensive environments.
- MakaleAçık Erişim2026Scopus SJRQ3Enhancing precision of low-cost detectors via machine learning for accurate mass attenuation coefficient estimation
Düzgün, İ.; Küçük, M.A.; Kaya, S.; Çelik, N.
Low-cost NaI(Tl) detectors are practical for gamma-ray spectrometry but their limited energy resolution can introduce systematic errors in mass attenuation coefficient measurements when scattered photons are included in the peak region. This study proposes a machine-learning correction framework that maps NaI(Tl)-derived attenuation coefficients to XCOM-based HPGe-equivalent reference values through a dimensionless correction factor. An EGS4/XCOM dataset of 756 model-development configurations, covering 18 atomic numbers, six monoenergetic photon energies, and seven collimator radii, was used to train twelve regression models and evaluate them over 60 randomized train–validation–test cycles. Sodium and Bismuth were withheld for external material-wise validation. Gaussian Process Regression with a Matérn 5/2 kernel provided the best overall testing performance. For the withheld materials, the correction reduced the mean deviation from XCOM references from 3.07% to 0.83%, supporting its use as a practical correction layer for low-cost attenuation measurements.
- MakaleAçık Erişim2026Scopus SJRQ2Computational analysis of radiation shielding properties of BaO-modified magnesium borophosphate glasses based on WinXCOM and EGS4 Monte Carlo simulations
Düzgün, İbrahim; Çelik, Necati; Kaya, Selim
The increasing use of ionizing radiation in medical, industrial, and nuclear applications necessitates the development of advanced and environmentally friendly shielding materials. In this study, the gamma-ray shielding performance of BaO-modified magnesium borophosphate glasses with compositions xBaO–30MgO–10P2O5–(50−x)B2O3–10Na2O (x = 0–35 mol%) was theoretically investigated. The radiation attenuation properties were evaluated over a wide photon energy range (59.54–2000 keV) using the WinXCOM database and Monte Carlo simulations based on the EGS4 code. Key shielding parameters, including mass attenuation coefficient (μ/ρ), half-value layer (HVL), mean free path (MFP), effective atomic number (Zeff), radiation protection efficiency (RPE), and gamma-ray kerma coefficients, were determined. The results indicate that increasing BaO content enhances the attenuation capability of the glass system, particularly in the low and medium photon energy regions, due to increased density and effective atomic number. A good agreement between WinXCOM and EGS4 results confirms the reliability of the applied theoretical approaches. These findings suggest that BaO-modified magnesium borophosphate glasses are promising candidates for radiation shielding applications.
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İncele - MakaleYalnız künye2026Scopus SJRQ2Computational gamma-ray attenuation and fast-neutron removal cross-section assessment of CrN, AlCrN and AlTiCrN ceramic coatings using EGS4 Monte Carlo and Phy-X/PSD
Sirin, Murat; Kaya, Selim; Aktarer, Semih Mahmut; Baltas, Hasan; Küçükömeroglu, Tevfik
In this study, the computationally predicted gamma-ray attenuation behavior and fast-neutron removal cross-section characteristics of micrometre-scale CrN, AlCrN, and AlTiCrN ceramic coatings produced via cathodic arc evaporation were investigated. The shielding parameters were not measured by direct gammaor neutron-transmission experiments; instead, mass attenuation coefficients (MAC, mu/rho) in the 0.05-2.50 MeV range were obtained from EGS4 Monte Carlo simulations and Phy-X/PSD calculations, and the agreement between the two computational datasets was evaluated. Energy-dependent attenuation parameters, including half-value layer (HVL), mean free path (MFP), effective atomic number (Zeff), radiation protection efficiency (RPE), and kerma coefficients, were calculated. Statistical comparison showed good consistency between EGS4 and Phy-X/PSD for MAC, RPE, HVL, MFP, and kerma coefficients, whereas Zeff exhibited larger method-dependent deviations. All coatings showed higher attenuation at low photon energies due to the photoelectric effect, while Compton scattering dominated at intermediate energies. Among the investigated coatings, CrN exhibited the most favorable calculated gamma-ray attenuation indicators, with lower HVL and MFP values and higher RPE values. The macroscopic fast-neutron removal cross-section (Sigma R) was also calculated as a first-order neutron attenuation indicator, and CrN showed the highest Sigma R value. Considering their limited thickness of approximately 2.3-2.8 mu m, these coatings should not be regarded as replacements for conventional bulk radiation shields. Instead, nitride-based ceramic coatings may serve as secondary or multifunctional surface layers in space-restricted components requiring local radiation attenuation and mechanical durability.
- MakaleYalnız künye2023Scopus SJRQ1Calculation of radiation shielding parameters of YBa2Cu3O7 and Y3Ba5Cu8O18 superconductors for the energies from 122 to 1332 keV using EGS4 code
Kaya, Selim
This Study aims to evaluate the radiation shielding efficiency of YBa2Cu3O7 and Y3Ba5Cu8O18 superconducting ceramics. In the current study, the radiation shielding efficiency of YBa2Cu3O7 and Y3Ba5Cu8O18 superconducting ceramics were calculated using the EGS4 code and discussed experimentally and theoretically by comparing with XCOM data. The mass attenuation coefficients (μ/ρ) for YBa2Cu3O7 and Y3Ba5Cu8O18 superconductors and their contents was investigated theoretically (EGS4 and WinXcom) and experimentally at gamma-ray energies from 122 to 1332 keV. The theoretical values have been computed in the energy range from 1 keV to 100 MeV using WinXcom program. Then, using the mass attenuation coefficients, it was determined some shielding parameters such as mean free path (MFP), half value layer (HVL), effective atomic number (Zeff), radiation protection efficiency (RPE) and gamma–ray kerma coefficients ((kγ). It has been seen that the theoretical and the empirical results were in agreement. The data and findings from this study can guide further research and development of shielding materials for gamma-ray and neutron shielding applications.
AtıfScopus13WoS11OpenAlex13İncele - MakaleAçık Erişim2023Scopus SJRQ2Calculation of the Effects of Silver (Ag) Dopant on Radiation Shielding Efficiency of BiPbSrCaCuO Superconductor Ceramics Using EGS4 Code
Kaya, Selim
In the current study, the effects of silver (Ag) additive on the radiation shielding efficiency of BiPbSrCaCuO superconducting ceramics was calculated using the EGS4 code and discussed theoretically by comparison with XCOM data. The mass attenuation coefficients (µ/ρ) for BiPbSrCaCuO superconductor ceramics and their contents were investigated theoretically (WinXcom and EGS4) at gamma-ray energies ranging from 59.5 to 1332 keV. The theoretical values were computed in the energy range from 1 keV to 100 MeV using the WinXcom program. Then, using the mass attenuation coefficients, some shielding parameters were determined, such as the mean free path (MFP), the half value layer (HVL), the effective atomic number (Zeff), the radiation protection efficiency (RPE), the macroscopic fast neutron removal cross-sections (ΣR, cm−1) and the gamma-ray kerma coefficients ((Formula presented.)). Theoretically, the results obtained with XCOM and EGS-4 were found to be in good agreement. The radiation shielding efficiency (RPE), neutron removal cross-section (ΣR, cm−1), maximum and semi-valent layer (HVL), and mean free path (MFP) values were found to be smaller for BiPbSrCaCuO superconducting ceramics as the silver (Ag) contribution was increased. Data from this study can guide further research and development of shielding materials for gamma-ray and neutron shielding.
AtıfScopus15WoS15OpenAlex20İncele - MakaleYalnız künye2021Scopus SJRQ3The First Measurement for Mass Attenuation Coefficients, Effective Atomic Numbers, and Electron Densities of Y123 and Y358 High-Temperature Superconductors (HTS) for the Energies from 46.6 to 1332 keV
Düzgün, İbrahim
Y123 and Y358 high-temperature superconductor phases have experimental mass attenuation coefficients (MAC) determined at 46.5, 81, 122, 302, 356, 383, 662, 1173, and 1332 keV photon energies. The experimental values have been compared with theoretical values acquired employing the XCOM software and database. It has been observed that the theoretical and the empirical results were in perfect agreement. Also, it has been seen that the comparison of the MACs for all specimens examined with the corresponding photon energies complies with the exponential absorption law. The effective atomic numbers (Zeff) and electron densities (Nel) of Y123 and Y358 superconducting phases in different energy ranges have determined experimentally and theoretically. The Y358 superconductor specimen is a relatively better absorber than the Y123 between 40 and 100 keV.
AtıfScopus3WoS4OpenAlex2İncele - MakaleYalnız künye2016Scopus SJRQ2A New Approach for Determination of Volumetric Water Content in Soil Samples by Gamma-Ray Transmission
Celik, Necati; Altin, Duygu; Cevik, Ugur
A new method was presented for the purpose of volumetric water content determination in any soil sample by gamma-ray transmission. Monte Carlo (MC) simulation technique was used to determine the functional behavior of the linear attenuation coefficient of soil samples having different water contents for three soil samples. Using this functional behavior, the linear attenuation coefficients of dry soil and water were obtained from the intercept and the slope, respectively. It was experimentally shown that the mass attenuation coefficients of soil samples were not sensitive to the chemical composition but only to the physical density. This independence was exploited in this study to obtain the linear attenuation coefficient of a completely dry soil which was found to be 0.1409, 0.1274, and 0.1657 cm−1 for Gumushane, Ardahan, and Trabzon soil, respectively. The linear attenuation coefficient of water was determined to be 0.09 cm−1. Then, the volumetric water contents were obtained by measuring the gamma-ray intensities passed through three wet soil samples. The results were found to be 0.186, 0.182, and 0.214 cm3 cm−3 for Gumushane, Ardahan, and Trabzon soil, respectively. The results obtained by the method introduced were compared with the results obtained using gravimetric method. A very good agreement was observed.
AtıfScopus7WoS7OpenAlex8İncele - MakaleYalnız künye2012Scopus SJRQ2Effect of detector collimation on the measured mass attenuation coefficients of some elements for 59.5-661.6 keV gamma-rays
Çelik, Necati; Çevik, Ugur; Çelik, Ahmet
Mass attenuation coefficients were determined experimentally for Sc, Ni and W for gamma energies of 59.5, 122, 276, 302, 356, 383 and 662 keV for different detector collimator diameters ranging from 2 to 10 mm. The aim was to investigate the quantitative analysis of detector collimator diameter effect on measured mass attenuation coefficients. It was found that measured mass attenuation coefficients decrease systematically with the increasing collimator diameter. The relative difference was found to be up to around 3% in some cases. The observed decrease in mass attenuation coefficients was attributed to the detection of elastic and inelastic scattered photons from the absorber. In elastic scattering process the photons change in direction but not in energy and get counted under the full energy peak if they reach the detector. In inelastic scattering however, both direction and energy of the scattered photons change. It was seen that most of the inelastic scattered photons also get counted by the detection system since they lose an amount of energy lower than the energy resolution of the detector. It is understood from the present results that it is essential to take into account the experimental geometry when reporting mass attenuation coefficients.
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