Selim Kaya

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.

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–10P ₂ O ₅ –(50−x)B ₂ O ₃ –10Na ₂ O (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.

Following the Chernobyl accident, Ordu province in Türkiye’s Eastern Black Sea region received significant 137Cs deposition. Mosses and lichens have been used as bioindicators at 50 sampling points in 1997, 2007, and again in 2025. This study presents the third measurement (2025) and calculates ecological half‑lives for the 2007–2025 period. Samples were collected from the same locations and species, and 137Cs activity was measured by HPGe gamma spectrometry. Detectable 137Cs was found in 14 of 30 moss sites (mean 10.1 Bq kg⁻¹) and 3 of 20 lichen sites (mean 5.2 Bq kg⁻¹). Ecological half‑lives for 2007–2025 averaged 4.4 years for mosses and 4.2 years for lichens, similar to values from 1997–2007. Nearly 39 years after Chernobyl, 137Cs remains detectable at very low levels. The consistent short ecological half‑life confirms that environmental removal continues to dominate over radioactive decay. This 28‑year dataset provides a robust baseline for long‑term radiocaesium monitoring.