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    A Monte Carlo investigation of some important radiation parameters and tissue equivalency for photons below 1 keV in human tissues
    (IOP Publishing Ltd, 2022) Rafiei, Mustafa Mohammad; Parsaei, Sara; Kaur, Parminder; Singh, K. J.; Büyükyıldız, Mehmet; Kurudirek, Murat
    The attenuation coefficients are important input values in estimating not only the dose and exposure in radiotherapy and medical imaging, but also in the proper design of photon shields. While studies are widely available above 1 keV, the attenuation coefficients of human tissues for photon energies less than 1 keV have not been studied yet. In this study, the attenuation coefficients of water and some human tissues were estimated for low energy photons using the MCNP6.1 code in the energy region 0.1 keV-1 keV. Mass attenuation coefficients were estimated at photon energies of 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 and 1000 eV for water and ten human tissues (Soft, Breast, Lung, Bone, Brain, Eye lens, Ovary, Skin, Thyroid and Prostate). Results were compared with those available in literature and a fairly good agreement has been obtained. These data were then used to calculate the mean free path, half value layer, tenth value layer, effective atomic number and specific gamma-ray constant (useful for calculation of dose rate) as well. Moreover, for comparison the effective atomic number of the water has been obtained using the results of this work and using the data available in NIST database from 0.1 to 1 keV. In addition, the human tissues were compared with some tissue equivalent materials in terms of effective atomic number and specific gamma-ray constant to study the tissue equivalency from the results, the muscle-equivalent liquid with sucrose has been found to be the best tissue equivalent material for soft tissue, eye lens and brain with relative difference below 4.1%.
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    Brass alloys improved with antimony additives for gamma-ray shielding applications
    (Pergamon-Elsevier Science Ltd, 2026) Levet, Aytac; Kaur, Parminder; Kahruman, Cem; Thakur, Sonika; Buyukyildiz, Mehmet
    In the present research, brass alloys (Cu-63, Zn-37) have been modified with antimony content ranging from 0 to 5 % to enhance their radiation resistance. Comprehensive analyses were conducted to evaluate the effects of antimony doping on both the microstructural and radiation attenuation characteristics of these alloys. Phase diagrams and microstructural analysis revealed dendritic structures and Sb accumulation at grain boundaries at higher concentrations. The crucial radiation shielding parameters, including mass attenuation coefficient (MAC), effective atomic number (Zeff), effective electron density (Neff), half-value layer (HVL), and mean free path (MFP), were investigated both experimentally and theoretically across photon energies ranging from 81 to 383.9 keV. Results show that increasing antimony content enhances radiation absorption, with the 5 % Sb alloy demonstrating the highest shielding effectiveness. The MAC of the A6 brass alloy containing 5 % Sb showed a 15.5 % increase relative to the standard A1 brass alloy at 81 keV. These findings suggest that antimony-doped brass alloys can serve as effective, non-toxic alternatives for radiation shielding in nuclear, medical, and industrial applications.
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    Gamma-ray attenuation properties of some heavy metal ferroalloys for potential applications
    (Pergamon-Elsevier Science Ltd, 2024) Buyukyildiz, Mehmet; Thakur, Sonika; Levet, Aytac; Kaur, Parminder
    In the present study, ferro manganese (HC), ferro chromium (MC), ferro silicon zirconium (FeSiZr), ferro silicon manganese (FeSiMn) and ferro silicon (FeSi 65%) ferroalloys have been investigated for nuclear radiation attenuation properties. For this aim, linear attenuation coefficients (LAC) were measured using Lambert-Beer law for transmission of the gamma rays at 81, 356, 661, 1173 and 1332 keV photon energies emitted from 133Ba, 137Cs and 60Co radioactive sources to irradiate the ferroalloys. The mass attenuation coefficient (MAC), halfvalue layer (HVL), tenth-value layer (TVL), and mean free path (MFP) of ferroalloys were then determined using LACs in the same photon energies. Effective atomic numbers (Zeff) of ferroalloys were also obtained using total atomic cross-sections (sigma a) calculated from MACs in the same photon energies. HC ferroalloy was found the best radiation shielding material due to the lower MFP and higher MAC values at the interested gamma ray energies at transmission geometry. The ferroalloys were also compared with some standard radiation shielding concretes. It was concluded that the ferroalloys showed better radiation shielding characteristics on behalf of MFP values at 356 keV photon energy. The studied ferroalloys have better MFPs between 2.91% (for FeSi 65%) and 66.81% (for HC) differences than standard concretes.
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    Investigation of radiological properties and water equivalence of polymer gel dosimeters in the energy range 0.1-10 keV
    (Korean Nuclear Soc, 2025) Levet, Aytac; Thakur, Sonika; Kaur, Parminder; Rafiei, Mustafa Mohammad; Parsaei, Sara; Buyukyildiz, Mehmet
    The interaction parameters of radiation with matter are crucial for accurately determining radiation doses in diagnostic and treatment. This study examined the radiological features of normoxic polymer gels used to measure radiation doses. The mass attenuation coefficient (MAC), mass energy-absorption coefficient (MEAC), effective atomic number (Zeff), half value layer (HVL) and mean free path (MFP) for these samples were determined in the energy range of 0.1 keV-10 keV. Zeff was established using direct and interpolation methods. The largest discrepancy for Zeff between the methods was observed for water, with a 48 % difference in the energy range of 0.3 keV-0.5 keV. MACs of the samples were compared with Monte Carlo simulation results based on FLUKA 4-3.1 code. MAC results obtained with simulation showed good agreement with Hubbell, and the maximum and minimum differences between them were seen in the FAT sample as 8.31 % and 0.08 %, respectively. Additionally, dose rate, gamma constant, and air kerma values were calculated using mass energy absorption coefficients for all samples and their water equivalence was evaluated in the relevant energy range. It was observed that the samples with radiological water equivalence and air kerma values close to 1 were PAGAT, MAGIC, MAGAS, and MAGAT.
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    Study of low-energy photon interactions below 1 keV for some biological molecules of human body
    (Springer Heidelberg, 2022) Mohammad Rafiei, Mustafa; Parsaei, Sara; Kaur, Parminder; Singh, K. J.; Buyukyildiz, Mehmet; Kurudirek, Murat
    In the present work, the authors have studied the radiation interactions at very low photon energies (below 1 keV) for some materials of biological importance, viz. water, glycerol, adenine, guanine, palmitic acid, myristic acid, valine, tryptophan, histidine, glucose and ribose. The parameters including mass attenuation coefficient, mean free path, half value layer, tenth value layer, effective atomic number, mass energy absorption coefficient, gamma constant and dose rate have been investigated in the energy range from 100 to 1000 eV. MCNP6.1 simulations have been employed in this study. Water was found to have higher values of mass attenuation coefficient and effective atomic number among the other materials, whereas palmitic acid possesses relatively lower values except for the energy region wherein abrupt changes occur near the K edge absorption energies. The values of mean free path, half value layer and tenth value layer were observed to be close to hair-like thickness or a thickness of few cell layers. Exposure to such low-energy photons can be very damaging to the skin cells and even the DNA. Such study will prove to be very useful for radiological applications.