Browsing by Author "Gultekin A."

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An analytical expression for electron elastic scattering cross section from atoms and molecules in 1.0 keV to 1.0 MeV energy range
(2006-07-31) Yalcin S.; Gurler O.; Gultekin A.; Gundogdu O.
In this Letter, an expression is presented to calculate elastic scattering cross sections for incident electrons as a function of both energy and atomic number in the energy range between 1 keV and 1 MeV for materials with effective atomic number between 3 and 18. The expression we present has a rather simple analytical form which gives accurate results that are in very good agreement with the results calculated by a relativistic partial-wave expansion method. Hence, this equation can be employed accurately and efficiently in a continuous manner, without the need to go through rather large look-up tables, thus making the whole process quick, efficient and removing possible computational errors that may arise from the efforts of interpolation. © 2006 Elsevier B.V. All rights reserved.
Microwave Curing Effect on Internal Sulphate Damage in Nano Alumina Reinforced White Cement
(2019-02-24) Kaplan G.; Demircan R.; Cakmak C.; Gultekin A.
In this study, microstructural investigation was carried out to analyse the internal sulphate damage in the nano-Al2O3 (nAl) reinforced white cement pastes. As white cement is generally used in the production of architectural concrete, 52.5 R type white cement was preferred in the scope of the study. Nano Al2O3 was substituted into the cement paste at 0% and 5% ratios. Three different methods were used for microwave curing. Different microwave curing techniques were performed as 120 minutes of 100 Watt application, 75 minutes of 100 Watt-30 minutes of 150 Watt-15 minutes of 200 Watt application, and 90 minutes of 100 Watt-15 minutes of 150 Watt-15 minutes of 200 Watt. In order to accelerate the formation of DEF damage, Na2SO4 was added to the cement paste at 2%, and 5% ratios. Three different microwave curing methods were used to investigate the occurrence of DEF damage in nano Al2O3 reinforced concrete concretes. In the pastes produced for this purpose, dense ettringite structure was observed. In cement pastes without nAl, the ettringite structure had a low S / Ca ratio (<0.20). More ettringite was formed in methods 2 and 3 used as microwave curing. The heat treatment applied in the microwave curing was the same as in other thermal curing applications, and in case the inner sulphate source was present it led to the formation of ettringite. This process became more evident in the presence of NA by increasing power application.
Mosses beta radioactivity in Katirh mountain-Bursa, TURKEY
(2007-08-03) Kahraman A.G.; Kaynak G.; Akkaya G.; Gultekin A.; Gurler O.; Yalcin S.
Mosses are one of the most widely used procedures to determine via plant of radioactive contamination. The high concentrating capacity of mosses may be used as bioindicator of environmental radioactive contamination. In this study, the mosses were collected in region of Katirh Mountain in northwestern Turkey, activities were determined using TENNELEC LB 1000-PW detector. Samples of mosses growing on soil, rock, and tree bark were collected. © 2007 American Institute of Physics.
Photon mass energy absorption coefficients from 0.4 MeV to 10 MeV for silicon, carbon, copper and sodium iodide
(2006-07-01) Oz H.; Gurler O.; Gultekin A.; Yalcin S.; Gundogdu O.
The absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy absorption coefficients for gamma rays with an incident energy range between 0.4 MeV and 10 MeV in silicon, carbon, copper and sodium iodide. The mass energy absorption coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature.