Browsing by Author "Yorgun, Nergiz Yildiz"

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Comprehensive Natural Radioactivity and Pollution Risk Assessments of Aquatic Media and Sediment in Lake Van (T?rkiye)
(Pergamon-elsevier Science Ltd, 2023) Zorer, Ozlem Selcuk; Yorgun, Nergiz Yildiz; Ozdemir, Omer Faruk; Ogun, Erdal; Aydin, Harun; Atici, Ataman Altug; Elp, Mahmut
This paper studies the radionuclide (137Cs, 226Ra, 232Th, 40K) activity concentrations and gross radioactivities in waters and sediments of Lake Van, which is the third largest closed lake (with no natural or artificial outlet) within the Earth. The physico-chemical parameters were measured and evaluated in the lake waters. The mean gross alpha activities in surface, middle and bottom waters are 0.04, 0.03 and 0.03 Bq/L, respectively, and in the same order, the mean gross beta activities are 0.30, 0.23 and 0.33 Bq/L, respectively. In sediment samples, the mean activity concentrations were measured as 1.98 Bq/g for gross-alpha, 3.46 Bq/g for gross-beta, 48.3 Bq/kg for 226Ra, 32.0 Bq/kg for 232Th, 540.1 Bq/kg for 40K and 25.9 Bq/kg for 137Cs. The radiation hazard parameters values based on the measured activities were calculated and Raeq values are lower than the world average value in all samples, while Dout and AED values are relatively high in some sediment samples.
Development and Production of Metal Oxide Doped Glasses for Gamma Ray and Fast Neutron Shielding
(Pergamon-elsevier Science Ltd, 2020) Aygun, Bunyamin; Sakar, Erdem; Cinan, Esra; Yorgun, Nergiz Yildiz; Sayyed, M., I; Agar, O.; Karabulut, Abdulhalik
In this study, new glasses were designed and produced that did not consist of toxic lead oxide (PbO). Unlike conventional glass with powdered silicon oxide (SiO2) added [cobalt oxide (CoO), cadmium tungsten oxide (CdWO4), bismuth oxide (Bi2O3), chromium oxide (Cr2O3), and boron oxide (B2O3)], new glass specimens were fabricated via melt-quenching. The total macroscopic cross-sections, mean free path, and transmission number were calculated using GEANT4 Monte Carlo code. The equivalent dose rates were measured for 4.5 MeV fast neutrons. Gamma attenuation experiments were conducted at several energies in a range of 53-383 keV. The experimental and theoretical results were compared with those of construction concrete, paraffin, glasses containing lead, borosilicate, normal window, and soda glasses. The new glass minimized both gamma and neutron radiation leaks that may occur in various fields such as radiation treatment, nuclear power plants, radioactive waste transport and storage, and space and laboratory research.
Evaluation of Gamma-Ray Attenuation Properties of Lithium Borate Glasses Doped With Barite, Limonite and Serpentine
(Walter de Gruyter Gmbh, 2018) Yorgun, Nergiz Yildiz; Kavaz, Esra; Oto, Berna; Akdemir, Fatma
The values of mass attenuation coefficient, the effective atomic number and the electron density of barite-doped, limonite-doped, serpentine-doped and undoped lithium borate glasses were obtained not only from experimental study using the narrow beam transmission method for 81, 121, 244, 276, 344, 383, 444 and 778 keV gamma energies with Hp-Ge detector, but also therotical work by WinXCom software (1 keV-10(5) MeV). From the obtained results, all glasses type mass attenuation coefficient values tend to decrease under the condition of increasing energy by means of varied interaction mechanism in different energy regions. In addition, the effect of chemical composition on shielding properties was also investigated. It is inferred that doping element with high atomic number improves the gamma rays shielding properties of system. Among the investigated samples, barite-doped lithium borate glasses have highest value of mass attenuation, which makes barite-doped samples good candidates for artificial radiation application where visual detection is especially required.
Gamma Photon Protection Properties of Some Cancer Drugs for Medical Applications
(Elsevier Science Bv, 2019) Yorgun, Nergiz Yildiz; Kavaz, Esra
Chemotherapy stops or slows down the growth and proliferation of cancer cells. Chemotherapy usually uses in combination with, surgery, radiotherapy or other treatments. Therefore, it is useful to calculate the photon interaction parameters to determine the energy accumulation and penetration in tissue due to the interaction of cancer drugs with radiation. In this work, the mass attenuation coefficient (mu/rho), half value layer (HVL) and effective atomic number (Z(eff)) of some cancer drugs (Tadocel, Fluro-5, Erbitux, Carboplatin, Temodal, Tamoxifen, Endoksan and Oxaliplatin) have determined experimentally at 13.81, 17.7, 26.34 and 59.54 keV photons emitted from Am-241-point source by using Si(Li) detector. Besides, we calculated theoretically the gamma-ray interaction parameters using the WinXCOM software program. Next to these, utilizing the GP fitting approach, exposure buildup factors (EBF) of the drugs determined up to 40 mfp in the energy range 0.015-15 MeV. Experimental and theoretical results have been found to be in harmony. Oxaliplatin and Carboplatin have larger mu and Z(eff) and lower HVL values than the other drugs under study. The smallest EBF values are observed for Endoksan, Oxaliplatin and Carboplatin for all of the penetration depths. Oxaliplatin, carboplatin and endoksan possess significantly good radiation absorbing effect.
Gamma Ray Buildup Factors of Lithium Borate Glasses Doped With Minerals
(Elsevier Science Sa, 2018) Kavaz, Esra; Yorgun, Nergiz Yildiz
Five parameters (G-P) fitting method was used to calculate the gamma ray energy absorption and exposure buildup factor values of barite-doped, limonite-doped, serpentine-doped and undoped lithium borate glass types for incident photon energy, between 0.015 MeV and 15 MeV, and penetration depths, 40 mean free path. It was observed that the buildup factor values vary with not only different incident gamma energy values, but also chemical composition of glass samples. According to our results, the barite and limonite doped glasses (B1, B2 and L2) have the lowest values of energy absorption and exposure buildup factors. Among the selected sample of glasses, the barite and limonite-doped glasses possessed superior gamma-ray shielding effectiveness due to their higher equivalent atomic number values and the lower energy absorption and exposure buildup factor values. In other words, the presence of highly equivalent atomic number minerals improves the gamma ray shielding characteristics of the lithium borate glasses. Moreover, EABF and EBF values were compared and discussed. (C) 2018 Elsevier B.V. All rights reserved.
Gamma-Ray Shielding Parameters of Li2b4o7 Glasses: Undoped and Doped With Magnetite, Siderite and Zinc-Borate Minerals Cases
(Walter de Gruyter Gmbh, 2019) Yorgun, Nergiz Yildiz
Designing new shielding materials and calculating their shielding parameters are important task to keep living in safe from hazardous effects of radiation. In this study, the lithium borate glasses with chemical formula (Li2B4O7)((100-x))Y-x (x= 0, 10, 20, 30 and 40 wt and Y = magnetite, siderite and zinc-borate) were fabricated via melt quenching technique. X-ray diffraction method was employed to confirm amorphous structure of fabricated glass samples. The glass sample's shielding parameters such as mass attenuation coefficient, effective atomic number, and half value layer were measured experimentally by the narrow beam transmission method for 81, 276, 302, 356, and 383 keV of incident photon energies. Also, WinXCom software was used to calculate theoretical shielding parameters from 1 keV to 10(5) MeV photon energy. Moreover, Geometric Progression (G-P) method was used to calculate exposure buildup factor (EBF) values for incident photon energy 0.015 MeV-15 MeV up to penetration depths of 40 mfp (mean free path). Among the obtained results, while Li2B4O7 glass with magnetite 40% has the highest mass attenuation and effective atomic number, it has the lowest half value layer and exposure buildup factor. The results show that the fabricated glass systems could be considered as a good candidate for radiation safety.