Mehmet Ertugrul

Measurement of Kβ/Kα intensity ratios for elements in the range 22≤Z≤69 at 59.5 keV

Measurements of Kβ/Kα intensity ratios in elements with 22≤Z≤69 have been carried out by stimulating the emission of K characteristic radiation by 59.5 keV monochromatic photons. The x-rays were measured using a Si(Li) detector (160 eV FWHM at 5.9 keV). The experimental results were compared with other theoretical and experimental values.

X-Ray attenuation coefficients at different energies and the validity of the mixture rule for compounds around the absorption edge

Abstract The total mass attenuation coefficients for the elements Co, Mn and Co2O3, compounds CoCl2.6H2O, CoSO4, CoSO4.7H2O, MnCO3, KMnO4, MnCl2.2H2O, and MnCl2.4H2O were measured at different energies between 4.508 and 11.210 keV using a secondary excitation method. Ti, Co, Ni, Cu, Zn, As, Se were chosen as secondary exciter. Gamma rays (59.5 keV) emitted from an 241Am annular source were used to excite a secondary exciter and Kα (K–L3, L2) lines emitted of a secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. It was observed that the mixture rule method is not suitable for determination of the mass attenuation coefficients of compounds, especially at energy that is near the absorption edge. Obtained values were compared with theoretical values.

L-subshell fluorescence cross sections and L-subshell fluorescence yields in elements 68 ⩽ Z ⩽ 92 by 59.5 keV photons

L-subshell (σ1 ,σ2 and σ3) x-ray fluorescence cross sections were measured for Er, Ta, W, Au, Hg, Tl, Pb, Bi, Th and U at an excitation energy of 59.5 keV using a Si(Li) detector coupled to a model 4096 computerized multi-channel analyser. The values of Li -subshell fluorescence yields (ω1, ω2 and ω3) have been measured for the same elements using the previously measured cross section values and the theoretical Li -subshell photoionization cross section Coster-Kronig transition probabilities and emission rates. It is observed that the measured Li (i = 1, 2 and 3) subshell x-ray fluorescence cross section and Li -subshell fluorescence yield (ω1, ω2 and ω3) values for the elements are in general agreement with the theoretical ones evaluated using L-subshell fluorescence yields and the L-subshell photoionization cross section.

Measurement of LI, Lα, Lβ and Lγ x-ray fluorescence cross-sections in heavy elements excited by 59.5 and 123.6 keV photons

L1, Lα, Lβ and Lγ XRF cross-sections were measured in heavy elements 73 ≤ Z ≤ 92 at excitation energies of 59.5 and 123.6 keV photons. Measurements were made using two excitation sources. The experimental values of the cross-sections were determined by measuring the absolute yield of L-subshell x-rays emitted from a target of a given element and thickness when it was bombarded with a known flux of photons of given energy. It is observed that the measured L XRF cross-section values for the elements are in general agreement with the theoretical ones evaluated using L-subshell fluorescent yields (ωi) and Coster-Kronig transition probabilities (fij) based on the relativistic Dirac-Hartree-Slater theory. The present and previous measured and calculated values of the cross-sections are tabulated to bring out the existing status of L x-rays production cross-sections.

Stepwise technique for accurate and unique retrieval of electromagnetic properties of bianisotropic metamaterials

Metamaterials (MMs) are artificial materials that have received attention recently because their built-in features create collective electromagnetic effects that are otherwise impossible, such as negative refraction, and because of their exotic electromagnetic applications, namely, perfect lens and invisibility cloaks. Depending on wave propagation characteristics, MMs possessing normally weak magneto-electric coupling coefficients start to exhibit stronger bianisotropic effects. Therefore, accurate electromagnetic characterization of these MMs is important. In this study, we adapt a stepwise method based on the Nicolson–Ross–Weir technique for accurate and unique retrieval of electromagnetic properties of bianisotropic MM slabs. For this goal, we have derived explicit expressions for unique retrieval of electromagnetic properties of these slabs and compared these expressions with those in the literature in the retrieval process. From the comparison, we note that derived expressions are appropriate for unique determination of electromagnetic properties of bianisotropic MM slabs. In the performance analysis of the stepwise method for different measurement scenarios, we considered different bianisotropic MM cell configurations (split-ring and Omega-shaped resonators as well as the same resonators with wire strips) and extracted their electromagnetic properties when measured/simulated scattering parameters have some thermal noise. We note that for most of the frequencies, the stepwise method retrieves correct electromagnetic properties even when a relatively higher normally distributed noise with zero mean value and with standard deviations of 0.015 is present. In addition to the influence of thermal noise on performance of the stepwise method, we also analyzed the effect of both increasing length slab and the frequency band on retrieved electromagnetic properties of the analyzed various bianisotropic MM slabs.

Measurement of the K shell absorption jump factor of some elements

Abstract K shell absorption jump factors for the elements 40⩽ Z ⩽60 have been derived from previously measured total atomic cross sections and from measured K α production cross sections. The results are in reasonable agreement with literature data.

Measurement of atomic L shell Coster-Kronig yields (f12, f23 and f13) for some elements in the atomic number range 59⩽Z⩽90

Non-radiative transitions cause changes in the generation of the intensity of the L lines. In order to investigate the physical quantities relevant to the L lines affected by the non-radiative transitions, experimental measurements were carried out using a Si(Li) x-ray spectrometer. Atomic L shell Coster-Kronig yields (f12, f13 and f23) for some elements in the atomic number range 59≤Z≤90 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in Z of the form ∑nanZn (except for f13) and compared with theoretical and with earlier fitted values.

Measurement of K alpha to L alpha intensity ratio of lanthanides following photoionization at 59.5 keV

K alpha to L alpha intensity ratios of 11 lanthanide elements have been measured following photoionization at 59.5 keV by using a Si(Li) detector. The measured values are in good agreement with theoretical results. The theoretical results were calculated from sigma Li expressions for nKLi not=0 and nKLi=0.

Noniterative Permittivity Extraction of Lossy Liquid Materials From Reflection Asymmetric Amplitude-Only Microwave Measurements

A very promising amplitude-only microwave method is proposed to noniteratively determine the complex permittivity of lossy materials, which possess at least 10 dB attenuation. It utilizes reflection-only measurements, which in some instances increases the performance of the determination since the accuracy of transmission measurements significantly decreases for high-loss materials. The method is very feasible for industrial-based applications since the implementation of the method requires very simple microwave components or inexpensive microwave instruments. However, the method requires different reflection-only measurements, which in turn necessitates elaborate preparation of the sample holder.

X-RAY FLUORESCENCE SPECTROMETRY ANALYSIS OF TRACE ELEMENTS IN FLY ASH SAMPLES OF KEMERKÖY THERMAL POWER PLANTS

Fly ash samples collected by means of an electrostatic precipitator from the lignite-fired Kemerköy Power Plants of the located in Turkey was analysed using X-ray fluorescence (XRF) technique. Five trace elements, namely Nd, Ba, Sr, Mo and As were quantified using XRF. These concentration values can be helpful in developing a environmental pollution abatement approach for various applications of fly ash such as cement manufacture, wastewater treatment, lightweight contraction aggregate, ceramic production, and secondary source in recovery of valuable elements.