Browsing by Author "Yaltay, N."

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Determination of Gamma and Fast Neutron Shielding Parameters of Magnetite Concretes
(Pergamon-elsevier Science Ltd, 2016) Oto, B.; Gur, A.; Kavaz, E.; Cakir, T.; Yaltay, N.
In this study, some gamma shielding parameters such as mass attenuation coefficient (mu(rho)), effective atomic number (Z(eff)), electron density (N-el) and buildup factors have been investigated for concretes with and without magnetite aggregate. The measurements have been carried out using 1.25 MeV (mean energy of 1.1732 MeV and 1.3325 MeV photons of a Co-60 radioactive source) gamma photons. The theoretical values of mu(rho) have been calculated in the energy range from 1 key to 100 GeV by WinXCom computer code and these values were used in order to calculate the values of Z(eff) and N-el. And fast neutron shielding parameter namely effective removal cross-sections (Sigma(R), cm(-1)) have been calculated. In addition, Energy absorption buildup factors (EABF) and exposure buildup factors (EBF) values of concrete samples have been calculated for photon energy 0.015-15 MeV up to 40 mfp (mean free path) penetration depths. The results of this study showed that the magnetite concrete is more efficient than the ordinary concrete for fast neutrons and gamma rays. (C) 2016 Elsevier Ltd. All rights reserved.
Photon Attenuation Properties of Concrete Produced With Pumice Aggregate and Colemanite Addition in Different Rates and the Effect of Curing Age To These Properties
(Pergamon-elsevier Science Ltd, 2015) Yaltay, N.; Ekinci, C. E.; Cakir, T.; Oto, B.
Radiation shielding properties of lightweight concrete produced with pumice aggregate and colemanite addition in different rates and effect of cure ages to the radiation shielding were investigated by using Co-60 (1250 key) radioactive source. Gamma rays were counted by 0.6 cc, Farmer type PTW (TM) Ion chamber. Experimental results were compared with the theoretical values calculated by WinXCom program. Consequently, colemanite addition make enhancement in the radiation shielding of the lightweight concrete, however there is no directly proportional relation between colemanite rate (0.4-2%) and attenuation properties of the lightweight concrete and cure age especially long timed, raises the linear attenuation coefficient and decreases the mean free path values. The theoretical values were obtained as nearby the experimental results, especially in the later cure ages (360 day). (C) 2014 Elsevier Ltd. All rights reserved.