Önder Şimşek

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.

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.

Measurement of radiative vacancy distributions for the L2, L3 subshell and M shell of some elements with atomic range 69≤Z≤92

Abstract K to L 2 , L 3 subshell and M shell a radiative transitions were measured using an energy disersive X-ray spectroscopy method. It was observed that these values are decreased with increasing atomic number. Present results were compared with previous theoretical results.

Alloying Effect on Kβ/Kα Intensity Ratios in CrxNi1−x and CrxAl1−x Alloys

Introduction The Kα X-rays and the Kβ X-rays are two main components of the K X-ray emission lines of an atom when its K shell electrons are ejected by γ-rays or other energetic particles. A precise measurement of the Kβ/Kα intensity ratios is of great interest for quantitative analysis of trace elements; this is important because by comparison with the relevant theoretical values based on atomic models, there is the possibility to test the validity of the models.

Measurements of the Efficiency of A Si(Li) Detector in the 5.5-60 keV Energy Region

Abstract The photopeak, intrinsic, and radial efficiency of a Si(Li) detector has been determined as a function of energy over the range 5.5 to 60 keV energy region using four standard sources. Furthermore, emission probabilities for the standard sources have been determined and compared with literature values.

Measurement of K to L shell vacancy transfer probabilities for the elements 46≤Z≤55 by photoionization

b Abstract The K to L shell vacancy transfer probabilities for nine elements in the atomic region 46FZF55 were determined by measuring the L X-ray yields from targets excited by 5.96 and 59.5 keV photons and using the theoretical K and L shell photoionization cross-sections. The L X-rays from different targets were detected with an Ultra-LEGe detector with very thin polymer window. Present experimental results were compared with the semi empirical values tabulated by Rao et al. wAtomic vacancy distributions product by inner shellionization, Phys. Rev. A 5 (1972) 997-1002x and theoretically calculated values using radiative and radiationless transitions. The radiative transitions of these elements were observed from the relativistic Hartree-Slater model, which was proposed by Scofield wRelativistic Hartree- Slater values for K and L shell X-ray emission rates, At. Data Nucl. Data Tables 14 (1974) 121-137x. The radiationless transitions were observed from the Dirac-Hartree-Slater model, which was proposed by Chen et al. wRelativistic radiationless transition probabilities for atomic K- and L-shells, At. Data Nucl. Data Tables 24 (1979) 13-37x. To the best of our knowledge, these vacancy transfer probabilities are reported for the first time. 2003 Elsevier Science B.V. All rights reserved.

Measurement of the Kα and Kβ X-rays polarization degree and polarization effect on the Kβ/Kα intensity ratio

Abstract The linear polarization degree of K α and K β X-rays of some elements in the atomic range 57⩽ Z ⩽69 has been measured. In addition, the polarization effect on the intensity ratio of these elements is investigated. It is found that the K β X-rays are more polarized than K α X-rays. The polarization effect on the K β /K α intensity ratio was investigated. Because the polarization of characteristic K X-ray is not found in the literature the comparison was not made with other experimental and theoretical results.

L2 sub-shell Coster–Kronig yield at Z=76 and 81

Abstract The total Coster–Kronig (CK) transition probability f23 for the L2–L3 transition in Os and Tl have been determined from measurements on L X-rays emitted following photoionization. The measurements were performed using a double reflection experimental set up and a Si(Li) detector. The values of f23 are 0.142±0.029 and 0.122±0.026 at Z=76 and 81, respectively. We compared our results with theoretically predicted values and semiempirical values.

Measurement of total atomic attenuation, total atomic photoelectric and total atomic scattering cross sections in the range 40⩽Z⩽52

Abstract Total atomic attenuation, total atomic photoelectric and total atomic scattering cross sections by measuring the transmission factor has been fairly accurately calculated. K X-ray fluorescence (XRF) spectra were measured for Zr, Nb, Mo, Ag, In, Sn and Te at excitation energy of 59.537 keV using Si (Li) detector coupled to a model computerised multi-channel analyser in a 2π geometry set-up. These measured cross sections were compared with the corresponding theoretical and good agreement was observed between the experimental and theoretical values.

Measurement of L shell fluorescence yields of seven elements in the atomic number range 79 ≤ z ≤ 92 using photoionization

L shell fluorescence yields were measured for Au, Hg, Tl, Pb, Bi, Th and U using a Ge(Li) detector. The targets were excited using 59.5 keV γ-rays from a 241 Am radioactive source of strength 400 MBq. The results obtained were compared with the theoretical values and other measured values. This comparison shows that the present results are in good agreement with earlier experimental and theoretical results.