Sürdürülebilir Kalkınma Amaçları

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Araştırmacılar(12)

• Açikel, Selami
• Altin, Duygu
• Caliskan, A.
• Çalışkan, Abdullatif
• Çelik, Necati
• Düzgün, İbrahim
• Gök, Abdulkadir
• Karabıdak, S.M.
• Kaya, Ali
• Kaya, Selim
• Takaoğlu, Zeynep Başkan
• Ünal, Nüket

• MakaleYalnız künye2026/r/gumushane/10229
  Computational 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.

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• MakaleAçık Erişim2026/r/gumushane/10669
  Comparative study of magnetic and electric quadrupole moments in boron (5B) isotopes

  Ali, Ahmed H.; Tfiha, Amir D.; Zakaly, Hesham M. H.; Jarallah, Naz T.; Issa, Shams A. M.; Abdulqader, Abdulqader S.; Çelik, Necati; Bhuyan, M.

  The magnetic moments and electric quadrupole moments of the B-5 isotopes were calculated using different nuclear interactions and sets of effective charges. Instead of relying on core polarization, the effective charges were adopted through a microscopic theoretical approach. The one-body density matrix (OBDM) elements for these isotopes were calculated using the NuShellX@MSU code. The calculations were carried out within the shell model framework, using both the p- and psd-model spaces (MS). These model spaces were selected for nuclei with proton number Z = 5 and neutron number N > 3. The theoretical results for magnetic and quadrupole moments were compared with available experimental data. Theoretical magnetic moments of the B-8,B-10,B-11,B-12,B-13 isotopes showed good agreement with experiment when using the p-MS with the pwt interaction, and the psd-MS with the psdmwk interaction. Similarly, the theoretical electric quadrupole moments reasonably well with the experimental values when using the p-MS with the pkuo interaction, and the psd-MS with the psdmwk interaction.

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• MakaleAçık Erişim2026/r/gumushane/10627
  Long-term decline of Chernobyl-derived 137Cs in mosses and lichens from the Eastern Black Sea region of Türkiye

  Çevik, Ugur; Çelik, Necati; Uzun, Kubra K.; Çelik, Ahmet; Koz, Bahadir; Özen, Songul A.; Yesilkanat, Cafer M.; Hacisalihoglu, Aylin; Özkalayci, Fatih; Kaya, Selim

  This study presents the third consecutive assessment of 13 Cs activity concentrations in the same 50 moss (7 species) and lichen (2 species) sampling points in Ordu province, T & uuml;rkiye, one of the most heavily contaminated areas following the Chernobyl accident. Samples were collected from exactly the same locations used in the 1997 and 2007 studies and analyzed by high-resolution gamma spectrometry. In 2025, detectable 13 Cs was found in 14 of 30 moss sites (47%) and 3 of 20 lichen sites (15%). For samples below the minimum detectable activity (MDA), a value of MDA/2 (0.93 Bq kg-1) was substituted for lichens, while moss samples below the MDA were excluded from regression. The ecological half-life (Teco) for the 2007-2025 period was 4.38 +/- 1.05 years for mosses and 4.18 +/- 0.61 years for lichens. For mosses, this is nearly identical to the 1997-2007 mean (4.4 years), while for lichens it decreased from 5.6 to 4.18 years, suggesting a slight acceleration in environmental removal. All Teco values remain far shorter than the physical half-life of 13 Cs (30 years), confirming that environmental removal processes dominate over radioactive decay. Residual 13 Cs is concentrated in higher-altitude areas, reflecting the original deposition pattern and slower removal in cooler, more humid microenvironments. Nearly 39 years after the accident, the radiological risk posed by residual trace levels is negligible. This 28-year dataset provides one of the longest continuous records of 13 Cs in epiphytic bioindicators and serves as a valuable baseline for future contamination events.

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• MakaleAçık Erişim2026/r/gumushane/10543
  A combined Monte Carlo, analytical, and experimental study of true coincidence summing correction factors for 152Eu

  Çelik, Necati; Ali, Ahmed H.; Apaydin, Gokhan; Çevik, Ugur; Açikel, Selami

  The radionuclide 152Eu presents a significant challenge in gamma-ray spectrometry due to its complex decay scheme and significant true coincidence summing (TCS) effects, especially in close-measurement geometries. This study presents a comprehensive investigation into TCS correction factors for the principal gamma-ray lines of 152Eu using tripartite methodology: a custom Monte Carlo (MC) simulation based on the EGS4 system, an established analytical method, and direct experimental measurements. The MC simulation explicitly models the complete decay process, including branching ratios, gamma emissions, internal conversion, and subsequent X-ray emissions for both decay branches (beta-minus to 152Gd and EC to 152Sm). Experimentally, correction factors were derived using a well-characterized point source measured at multiple distances with a coaxial HPGe detector. The analytical, method based on probabilistic analysis of the decay scheme, served as an examination. Results demonstrate that the analytical method underestimated the TCS correction factors, particularly for low-energy lines such as 121.78 keV, where it predicted a mere 0.78 % correction compared to 25.5 and 23.5 % from MC and experiment, respectively. This discrepancy is attributed to the analytical method's neglect of gamma-X ray coincidences and the internal conversion effects. In contrast, the MC simulation showed remarkable agreement with experimental results across all energies, validating its capability to accurately model the full complexity of TCS effects. The study concludes that while analytical methods offer rapid estimates, MC simulations, especially when experimentally validated, are essential for achieving metrological accuracy in the gamma-ray spectrometric analysis of complex radionuclides like 152Eu.

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• MakaleYalnız künye2026/r/gumushane/14223
  Optimizing compton suppression systems: A parametric monte carlo study of NaI scintillator geometry

  Kaya, Ali; Çelik, Necati; Kaya, Selim

  Compton suppression systems are widely used to enhance gamma-ray spectral quality in applications such as nuclear safeguards and environmental radioactivity measurements. Although optimization of high-purity germanium (HPGe) detectors has been extensively reported, the geometric optimization of secondary sodium iodide [NaI(Tl)] scintillation detectors remains less studied. This work investigates the influence of annular and plug NaI(Tl) detector geometry—length, thickness, and radius—on Compton suppression performance using Monte Carlo simulations. Performance is evaluated in terms of the peak Compton suppression factor (CSFpeak) and total Compton suppression factor (CSFtotal). The results show that CSFpeak and CSFtotal increase with plug length (2–10.2 cm) and annular thickness (1–5.85 cm), with saturation observed beyond approximately 8–10 cm and 4–5 cm, respectively, due to reduced incremental photon absorption. The plug detector radius (3.72–5.1 cm) exhibits a nonlinear effect, with optimal performance achieved at 4.55–4.83 cm, beyond which gains are marginal (<5%). Suboptimal geometries (plug length <6 cm, annular thickness <3 cm, plug radius <4.28 cm) result in 20–60% lower suppression performance, increasing Compton continuum contributions in 662 keV spectra. The optimal configuration—plug length of 8–10 cm, plug radius of 4.55–4.83 cm, and annular thickness of 4–5 cm—achieves more than 90% of maximum CSFpeak and CSFtotal while maintaining a balance between performance and detector volume. These results provide quantitative design guidelines for optimizing NaI(Tl)-based Compton suppression systems for improved gamma-ray spectrometry performance.

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• MakaleAçık Erişim2026/r/gumushane/14195
  La2O3 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.

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• MakaleAçık Erişim2026/r/gumushane/13874
  Monte Carlo calculation of geometry-dependent true coincidence summing correction factors for the gamma-rays of 214Bi in HPGe detectors

  Çelik, Necati

  True coincidence summing (TCS) effects in gamma-ray spectrometry introduce significant systematic uncertainties in activity determinations, particularly for radionuclides with complex decay schemes such as 214Bi. This study presents a comprehensive Monte Carlo investigation of TCS correction factors (CFs) for seven major gamma-ray lines of 214Bi. The primary contribution of this study is the systematic decoupling of detector geometry effects: nine distinct HPGe detector configurations were simulated with varying crystal dimensions, dead layers, and hole geometries, followed by an isolated analysis of crystal radius versus crystal length contributions for both point and extended source geometries. The decay scheme of 214Bi was meticulously modeled using Nucleide 2000 data, incorporating all beta branches, gamma transitions, internal conversion coefficients, and cascade probabilities to ensure high-fidelity representation of the decay scheme. Results demonstrate that crystal radius exerts a substantially stronger influence on TCS CFs than crystal length, with point source values at 609.3 keV increasing by 18.2% across the radius range of 2.1–4.5 cm, compared to only 3.7% variation across the length range of 3–11 cm. Extended source geometries reduce TCS CFs by 5%–11% compared to point sources across all configurations, highlighting the mitigating effect of distributed sources. Energy-dependent behavior is also evident: the 609.3 keV line exhibits strong summing-in (CF > 1.3 for large detectors), while the 1377.7 keV line shows dominant summing-out (CF < 0.86). These findings provide gamma-ray spectrometrists with insight into the relative importance of detector dimensions for TCS effects, suggesting that crystal radius is the primary geometric parameter influencing coincidence summing corrections. The observed trends illustrate how TCS corrections vary with detector dimensions, offering spectrometrists a basis for understanding the relative sensitivity of these corrections to different geometric parameters.

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• MakaleAçık Erişim2026/r/gumushane/13868
  CsPbBr3 single-crystal growth by temperature-lowering method as a case study for EGS4 benchmarking against commercial radiation detectors

  Akbulut Özen, Songül; Özen, Murat; Çelik, Necati

  CsPbBr3 single-crystals were synthesized using a hydrobromic acid–based temperature-lowering method, and their structural and optical properties were confirmed by XRD, DSC, and UV–Vis analyses. A solubility curve was established to optimize growth conditions, enabling enlargement of the seeded crystals. The radiation detection potential of CsPbBr3 was evaluated using EGS4 Monte Carlo simulations across photon energies ranging from 10 keV to 1 MeV. Simulated full-energy peak efficiencies and resolution values were compared with conventional detectors (Si(Li), NaI, and HPGe) and with alternative perovskite derivatives (CH3NH3PbBr3, Cs4PbBr6, CsPb2Br5). CsPbBr3 exhibited efficiency scaling with detector volume and resolution behavior consistent with the statistical 1/√E dependence typical of direct-gap semiconductors. While HPGe maintained superior intrinsic resolution, CsPbBr3 offered promising room-temperature performance without cryogenic requirements. These results demonstrate that the temperature-lowering method provides a viable route to scalable CsPbBr3 single-crystals and confirm their potential as cost-effective, high-Z semiconductor detectors for X- and γ-ray applications. The findings establish a foundation for the further optimization of perovskite-based radiation detection technologies.

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• MakaleAçık Erişim2026/r/gumushane/13867
  Distribution and radiological risk assessment of natural and artificial radionuclides in soils from the Aktutan hydrothermal alteration zone, Türkiye

  Kaya, Ali

  This study investigates the distribution of natural radionuclides (226Ra, 232Th, and 40K) and the artificial radionuclide 137Cs in soil samples collected from the Aktutan hydrothermal alteration zone in Gümüşhane, Türkiye. Hydrothermal systems are known to enhance radionuclide mobility and enrichment due to fluid–rock interactions, making them important environments for radiological assessment. However, no previous comprehensive radiological study has been conducted in this region. A total of 12 soil samples were collected and analyzed using high-purity germanium (HPGe) gamma-ray spectrometry. The measured activity concentrations ranged from 16 to 58 Bq·kg−1 for 232Th, 5 to 282 Bq·kg−1 for 226Ra, and 246 to 647 Bq·kg−1 for 40K, while 137Cs was detected in several samples with a maximum value of 5.7 Bq·kg−1. The elevated 226Ra concentrations observed in specific locations may be associated with localized hydrothermal alteration and possible uranium enrichment. Radiological hazard parameters, including absorbed dose rate, annual effective dose, radium equivalent activity, and hazard indices, were calculated. Most values were within internationally recommended limits; however, two sampling sites exhibited elevated radiological risk indicators, particularly in terms of excess lifetime cancer risk. Although the number of samples is limited, the selected locations represent areas of intense hydrothermal alteration and provide preliminary insight into radionuclide distribution in the region. The findings highlight the importance of localized geological controls on radioactivity and suggest the need for continuous environmental monitoring in areas with elevated radionuclide concentrations.

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• MakaleYalnız künye2026/r/gumushane/13791
  Influence 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.

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