İlgi alanları

Sürdürülebilir Kalkınma Amaçları

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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/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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• MakaleYalnız künye2026/r/gumushane/13788
  Natural Radioactivity and Radiological Risk Assessment of Rocks Around the Mines: A Case Study From the Mastra and Hazine Mağara Mining Areas, Northeastern Türkiye

  Sipahi, Ferkan; Çelik, Necati; Gücer, Mehmet Ali; Dizman, Serdar

  This study presents a comprehensive assessment of natural radioactivity levels and associated radiological hazards in rock samples collected from Mastra and Hazine Mağara mining sites in the Gümüşhane province, Türkiye. The concentrations of primordial radionuclides (226Ra, 232Th, and 40K) were measured in samples of andesite, granite, and limestone using a High Purity Germanium (HPGe) detector. Complementary whole-rock geochemical analysis (XRF and ICP-MS) was conducted to understand the geochemical controls on radioactivity concentrations. The results reveal significant heterogeneity in activity concentrations both within and between the two sites. For 226Ra, the Hazine Mağara site exhibited a wider range (2.44–22.57 Bq kg−1) with a higher maximum value compared to Mastra (2.65–13.96 Bq kg−1). Similarly, 232Th and 40K activity concentrations showed considerable variability, often linked to the presence of specific accessory minerals like zircon, monazite, and K-feldspar. Geochemical data indicated that element concentrations (K, U, Th) were generally lowest in limestone and highest in granite, showing a strong correlation with the measured activity concentration values. Radiological risk indices, including radium equivalent activity, absorbed dose rate, annual effective dose equivalent, and excess lifetime cancer risk, were calculated. While values remain below international public health safety limits, localized anomalies were identified. Multivariate statistical methods were used to determine the relationship between the 226Ra, 232Th, 40K, Raeq (Bq/kg), Ig, Hex, D (nGy/h), AEDE (μSv/y), AGDE (μSv/y), and ELCR (×10−5). The study concludes that despite these localized anomalies, both mining areas pose an overall minimum environmental radiation risk, underscoring the necessity for site-specific assessments to ensure safe resource utilization and radiation protection.

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• MakaleAçık Erişim2026/r/gumushane/13588
  Enhancing 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.

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• MakaleAçık Erişim2026/r/gumushane/13581
  Computational 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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• MakaleAçık Erişim2026/r/gumushane/13561
  A Comparative Study of 137Cs Dose Factors for Constant and Depth-dependent Soil Densities

  Çelik, Necati; Akçay, Nilay; Çevik, Uğur

  Accurate assessment of external radiation dose rates from 137Cs is essential for evaluating radiological risk in environmental and occupational settings. This study refines dose conversion coefficient calculations by incorporating depth-dependent soil density and addressing limitations in conventional methods that assume constant soil density. We calculated dose conversion coefficients for 137Cs in soil, considering both exponential and Gaussian distributions of activity concentration. Using two models, one with constant density and another with variable density as a function of depth, we compared dose rates to quantify the effect of soil density variations. Results indicate that dose rates are consistently higher when depth-dependent density is applied. The effect is more pronounced when 137Cs activity is distributed over larger depths (i.e., greater relaxation lengths) or when broader Gaussian distributions are considered. This suggests that assuming constant soil density may lead to underestimations of dose rates, especially in heterogeneous or compacted soils. Our findings emphasize the importance of accounting for density variability in dose calculations to enhance radiological risk assessments for areas contaminated with 137Cs.

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