Sürdürülebilir Kalkınma Amaçları
Yazarlar
Yayınlar
- 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.
- MakaleAçık Erişim2026La2O3 addition's effect on sodium-barium borosilicate glasses' radiation shielding capability: WinXCOM and EGS4 Monte Carlo analysis
Kaya, Selim
This study thoroughly investigated the impact of La2O₃ inclusion on the radiation shielding effectiveness of sodium-barium borosilicate glasses using EGS4 Monte Carlo simulations and WinXCOM computations. The gamma-ray shielding behavior of a set of glass samples was systematically investigated over a wide photon energy interval ranging from 50 to 2506 keV. The glass compositions were modified through the stepwise substitution of Na₂O with La₂O₃. Key radiation interaction and shielding metrics—including the mass attenuation coefficient (μ/ρ), half-value layer (HVL), mean free path (MFP), radiation protection efficiency (RPE), effective atomic number (Zeff), and kerma coefficients—were determined and comparatively evaluated. The results demonstrate that the progressive incorporation of La₂O₃ leads to a marked enhancement in radiation shielding performance, particularly within the low-and intermediate-photon energy ranges where photoelectric interactions prevail. The inclusion of La₂O₃ results in increased material density, μ/ρ, Zeff, and kerma values, while simultaneously reducing (HVL) and MFP.In conclusion, sodium-barium borosilicate glasses treated with La₂O₃ have better radiation attenuation capacities than their La₂O₃-free counterparts. These results validate the effectiveness of La₂O₃ substitution as an approach for customizing borosilicate glass systems for applications that need improved radiation shielding.
- MakaleYalnız künye2026Influence 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 Erişim2026Computational 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.
- MakaleYalnız künye2026Assessment of gamma-ray attenuation properties in advanced ceramics incorporating colemanite, pyrophyllite, and plastic clay
Uysal, Turan; Kaya, Selim
This study investigates the gamma-ray and neutron shielding performance of advanced ceramic composites containing colemanite, pyrophyllite, and plastic clay as environmentally friendly alternatives to conventional lead-based shielding materials. Gamma-ray attenuation properties were evaluated over the energy range of 59.54–2000 keV using theoretical calculations from WinXCOM and Monte Carlo simulations performed with the EGS4 code. Excellent agreement between the two methods confirmed the reliability of the simulation results. The mass attenuation coefficient (μ/ρ) decreased with increasing photon energy due to the transition from photoelectric absorption to Compton scattering and pair production mechanisms. Correspondingly, the half-value layer (HVL) and mean free path (MFP) increased, while radiation protection efficiency (RPE) decreased with photon energy. The effective atomic number (Zeff) exhibited an energy-dependent decline, reflecting changes in dominant photon–matter interaction processes. Neutron shielding performance improved with increasing colemanite content owing to the presence of boron-rich phases, and Sample-5 exhibited the highest fast neutron removal cross-section (ΣR = 0.11062 cm−1). The same sample also showed the highest gamma-ray kerma coefficients, indicating enhanced energy absorption capability. Overall, the results demonstrate that colemanite-enriched ceramic composites provide effective combined gamma-ray and neutron shielding and represent promising, sustainable, and non-toxic alternatives for radiation protection applications.
- MakaleYalnız künye2018Investigation of radiation absorption coefficients of lead-zinc mine waste rock mixed heavy concrete at 662–1460 keV energy range
Çullu, Mustafa; Bakırhan, Emir
The objective of this study is to observe the radiation shielding efficiency of concrete produced by using the lead wastes that are stored in lead-zinc mines processing of which is not financially viable in the mines they are extracted from that have negative effects on the environment. Within this scope, concretes were produced to be used as radiation shield concretes. The samples were prepared by altering the amounts of heavy aggregates such as lead–zinc mine waste, Magnetite, Limonite, and Barite at 25%, 50%, and 75% ratios, and concrete samples were prepared in C16/20, C25/30, and C35/45 concrete strength grades to determine the effects of these grades on radiation absorption properties. In order to determine the radiation absorption coefficients, absorption coefficients at 662 keV, 1173 keV, 1332 keV, and 1460 keV energy levels from Cs-137, Co-60 and K-40 sources were determined by concrete slabs with dimensions of 20 × 20 × 5 cm.
- MakaleYalnız künye2016Determination of the effect of lead mine waste aggregate on some concrete properties and radiation shielding
Çullu, Mustafa; Ertaş, Haydar
The aim of this study is to determine the radiation absorption capacity of concretes produced from lead mine waste which cannot be processed economically as the lead content is low in the mines they are extracted. Lead mine waste (tallow) were exchanged at ratios of 25%, 50% and 75% respectively with barite and limestone aggregates and samples were prepared at C16, C25 and C35 classes. The compressive strength and the unit weight of the prepared samples were determined. The linear absorption coefficients of prepared concrete samples at 662 keV of energy were determined. In addition the relationship between the radiation absorption capacity and the compressive strength–unit weight was investigated. The experiments demonstrated that best absorption was in concrete samples with 100% barite content (100B). On the other hand in the concrete samples prepared from the mixture of limestone and lead mine waste aggregates, it was observed that radiation absorption capacity decreased due to decreasing amount of barite. In concrete samples prepared from the mixture of lead mine waste and limestone aggregates, it was observed that radiation absorption capacity increased due to increasing amount of mine waste aggregates in the concrete. As a result it was observed that lead mine waste aggregates do not absorb as much radiation as barite aggregates depending on the ratio increase of lead mine waste in the aggregate added to the concrete mixture. However the absorbed radiation amount was observed to be higher compared to limestone aggregates.
