Onder Simsek

A new method for the determination of incoherent differential scattering cross sections

With the help of a Si(Li) detector, incoherent scattering cross sections of Ag, In and Sn were determined from 40°-135° in the case of 59.54 keV gamma rays of Am-241. A new method has been developed to determine differential incoherent scattering cross sections of elements. This method is based on simultaneous measurement of fluorescence radiation and scattered radiation, thus avoiding problems with measuring the source strength and source-to-detector solid angle. The results are compared with the non-relativistic Hartree-Fock values of Hubbell et al .

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.

An Accurate Complex Permittivity Method for Thin Dielectric Materials

A promising microwave method has been proposed to accurately determine the complex permittivity of thin materials. The method uses amplitude-only scattering parameter measurements at one frequency for this purpose. It resolves the problems arising from any offset of the sample inside its cell in complex reflection scattering parameter measurements and from any uncertainty in sample thickness in transmission scattering parameter measurements. The method determines unique permittivity since, for thin samples, multi-valued trigonometric terms can be linearized. It uses higher order approximations to extract highly accurate permittivity values. It works very well in limited frequency-band applications or for dispersive materials since it is based upon point-by-point (or frequency-byfrequency) measurements. For validation of the method, we measured the complex permittivity of two thin polytetrafluoro-ethylene (PTFE) samples.

Analysis of titanium and zirconium in red mud with energy dispersive x-ray spectrometry

Abstract An energy dispersive x-ray fluorecence technique was used for the determination of Titanium (Ti) and Zirconium (Zr) in red mud by using a standard addition method. An annular 241Am source is employed for excitation of K shells of elements.

Measurement of probabilities of radiative vacancy transfer from the L3 subshell to the M shell and the N shell for Pb, Th and U

The probabilities of radiative vacancy transfer from the L3 subshell to the M shell and to the N shell are deduced for Pb, Th and U by measuring the L3 x-rays and using theoretical L3-subshell fluorescence yields. To obtain L3 x-ray spectra of Pb, Th and U, the measurements are made using selective photoionization of the L3 subshell in these elements. The results are compared with theoretical values based on the relativistic Dirac-Hartree-Slater calculations. To the best of our knowledge, these radiative vacancy-transfer probabilities are reported for the first time.

A Microwave Method for Unique and Non-Ambiguous Permittivity Determination of Liquid Materials from Measured Uncalibrated Scattering Parameters

A new microwave method based on calibration- independent measurements has been proposed for non-ambiguous com- plex permittivity determination of liquid materials. We have derived a function in terms of the flrst-re∞ection coe-cient of the sample using raw complex scattering parameter measurements of three measurement conflgurations. We have verifled the proposed method from measure- ments of two liquid test samples with the available reference data in the literature.

Measurement of Coster-Kronig yields of the L2 subshells of Er, Yb and Hf

The Coster-Kronig yields, f23, were measured for Er, Yb and Hf using a Si(Li) detector employing the double reflection geometry set up. The results (0.159?0.012,0.149?0.013 and 0.138?0.010, respectively) are in good agreement with the theoretically predicted values.

L X-ray intensity ratios in heavy elements at 59.5 and 122 keV photons

The L shell X-ray intensity ratios ILα/ILβ, ILα/IL1 and ILα/ILγ for Ta, W, Re, Au, Hg, Tl, Pb, Bi, Th and U have been measured at excitation energies of 59.5 and 122 keV with a Si(Li) detector. Measurements have been performed using Am-241 and Co-57 radioisotope sources. A comparison is made of the experimental results with calculated values obtained using theoretical X-ray emission rates, subshell ionization cross-sections, subshell fluorescence yields and Coster-Kronig transition probabilities. A fairly good agreement is observed between experimental and theoretical values.

ON THE APPLICATION OF MICROWAVE CALIBRATION- INDEPENDENT MEASUREMENTS FOR NONINVASIVE THICKNESS EVALUATION OF MEDIUM- OR LOW- LOSS SOLID MATERIALS

Microwave methods require some sort of calibration before physical (thickness, flaw, etc.) and electrical (permittivity, permeability, etc.) measurements of materials. It is always attractive to devise a method which not only eliminates this necessity but also saves time before measurements. Microwave calibration-independent measurements can be utilized for this goal. However, in the literature, these measurements are only applied for electrical measurements of materials. In this research paper, we investigate the performance of microwave calibration-independent measurements for thickness evaluation of dielectric materials to increase the potential of available microwave techniques for thickness evaluation of dielectric materials. We derive an explicit expression for thickness estimation of dielectric materials from calibration-independent measurements for the adopted calibration-independent technique. We also propose a criterion for increasing the performance of measurements. We conducted thickness measurements of six dielectric specimens with different lengths to validate the derived expressions and the proposed criterion for thickness measurements.

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

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