X-ray Production Cross Sections Research Articles

Spectroscopic investigations of L-shell ionization in heavy elements by electron impact

The absolute L subshell specific electron impact ionization cross sections near the ionization threshold (16<E<45keV) of lead and thorium are obtained from the measured L X-ray production cross sections. Monte Carlo simulation is done to account for the effect of the backscattered electrons, and the final experimental results are compared with calculations performed using distorted wave Born approximation and the modified relativistic binary encounter Bethe model. The sensitivity of the results on the atomic parameters is explored. Observed agreements and discrepancies between the experimental results and theoretical estimates, and their dependence on the specific atomic parameters are reported.

Measurements of L-shell X-ray production cross-sections of Ag and Sb by low-energy electron impact

Abstract The total L-shell X-ray production cross-sections of Ag and Sb elements were measured by detecting the characteristic X-rays induced by the electron impact in the energy range of 6–28 keV. In this experiment, the thin films with thick aluminum substrates were used as the targets, and the experimental setup was improved. The influence of multiple scattering of electrons penetrating the targets films, electrons reflected from the thick aluminum substrates and bremsstrahlung photons produced when incident electrons impacted the targets were corrected by using the Monte Carlo method. The experimental results determined in this paper were compared with some theoretical models and other available experimental data in the literature. It was shown that the L-shell X-ray production cross-sections of Ag and Sb elements measured in this paper were in good agreement with the theoretical predictions within the uncertainties.

Angular distributions of differential X-ray production cross sections for Cu and Ta in photoionization

Abstract The characteristic K-shell X-ray emission of Cu and L X-rays of Ta in photoionization has been measured at excitation energy of 15.9 keV. The differential X-ray production cross sections of Kα and Kβ for Cu and Lα, Lβ1, Lβ2, Lγ1 for Ta are derived at emission angles ranging from 100° to 150°. The ratio of Kβ and Kα X-ray production cross sections, Kβ/Kα, is calculated for Cu and it is found to be consistent with other work even at different incident energy. While the ratios of Lα/Lβ, Lα/Lγ1 and Lβ/Lγ1 for Ta are found to be different with other results at different excitation energy. The reasons giving rise to this discrepancy are clarified with thorough analysis.

X-ray emission from 424-MeV/u C ions impacting on selected target**Project supported by the National Basic Research Program of China (Grant No. 2010CB832902), the National Natural Science Foundation of China (Grant Nos. 11505248, 11375034, U1532263, 11275241, 11205225, 11105192, and 11275238), and the Scientific Research Program of Education Bureau of Shaanxi Province, China (Grant No. 15JK1793).

The K-shell x-rays of Ti, V, Fe, Co, Ni, Cu, and Zn induced by 424-MeV/u C6+ ion impact are measured. It is found that the K x-ray shifts to the high energy side and the intensity ratio of Kβ/Kα is larger than the atomic data, owing to the L-shell multiple-ionization. The x-ray production cross sections are deduced from the experimental counts and compared with the binary encounter approximation (BEA), plane wave approximation (PWBA) and energy-loss Coulomb-repulsion perturbed-stationary-state relativistic (ECPSSR) theoretical predictions. The BEA model with considering the multiple-ionization fluorescence yield is in better consistence with the experimental results. In addition, the cross section as a function of target atomic K-shell binding energy is presented.

K-shell X-ray production in Silicon (Z2 = 14) by (1 ⩽ Z1 ⩽ 53) slow ions

K-shell X-ray emission of Silicon induced by near-Bohr-velocity ions was systematically investigated in collision systems for which the ratio of projectile-to-target atomic numbers (Z1/Z2) ranged from 0.07 to 3.79. The results show that, in asymmetric collisions, the measured K-shell X-ray production cross sections of Silicon fit very well with the predictions of different direct ionization models depending on the atomic number of projectile. In the case of near-symmetric collisions (Z1/Z2∼1), an obvious enhancement of the X-ray production cross section was observed, which can be attributed to the vacancy transfer within the framework of quasi-molecular model.

Vanadium K-shell X-ray emission induced by xenon ions at near the Bohr velocity

The X-ray emission spectra produced by 2.4-6.0 MeV Xe20+ ions impacting on vanadium surface were measured. The V K-shell X-ray production cross sections were extracted from the experimental yield data and compared with the theoretical predictions of the binary encounter approximation (BEA), the plane wave born approximation (PWBA), and the energy-loss coulomb-repulsion perturbed-stationary-state relativist (ECPSSR). In order to predict reasonably the inner-shell ionization induced by highly charged heavy ions during the asymmetric collisions at near the Bohr velocity, the corrections of BEA model are discussed. It is found that the X-ray production cross section induced by highly charged heavy ions moving at near the Bohr velocity is on the magnitude of 1 barn, which is almost four orders of magnitude larger than that induced by proton. The ECPSSR, which is regarded as the best model to simulate the inner-shell ionization by light ions, may underestimate the experimental data at least three orders of magnitude. The PWBA model presents a prediction to the results on an order of magnitude better than the ECPSSR simulation, but gives a worse tendency than the BEA model. The BEA calculations, corrected both by Coulomb repulsion and effective nuclear charge, present the best agreement with the experimental results. It is proposed, that in the energy region near the Bohr velocity, during the asymmetric collisions of Xe20+ ions with V atoms, the K-shell electron of V is ionized by direct ionization, and that it can be described by the binary encounter process between the xenon ions and the bound electrons. The X-ray production cross section can be simulated by BEA model, but the corrections of Coulomb repulsion and effective nuclear charge must be considered.

Use of a silicon drift detector (SDD) in the quantitative analysis of in-air PIXE

In the present study, we used a silicon drift detector (SDD) for the quantitative analysis of in-air PIXE. First, we examined the basic performances of the detector. We found that the shift of the peak position was less than 0.45 eV, and the energy resolution was 130–136 eV at 5.98 keV. We then used the SDD for a quantitative analysis. Physical parameters, such as the X-ray production cross-sections, values of the transmission of X-rays through absorbers and the detection efficiencies, which are required for quantification, were obtained theoretically and experimentally. We confirmed that many elements, from magnesium to barium, were able to be detected without using any special device. The results of the quantitative analyses of a few standard materials showed good agreement with the certified values. This method was also used to analyze practical samples, including bio-medical samples, and the results were in good agreement with the results obtained with in-vacuum PIXE.

Determination of Kα,β excitation factors in thin target for selected elements from Y to Te at 59.54 keV excitation energy

The paper presents the first measurements of the Kα and Kβ excitation factors for some selected elements from Y to Te. To determine the Kα and Kβ excitation factors, the experimental values of K shell X-ray production cross sections and total absorption photoelectric cross sections were used. The measurements were performed using a Si(Li) detector coupled with 2048 multichannel analyzer and an Am-241 annular radioisotope source which is emitted 59.54keV γ-photons. It is observed that the Kα excitation factors are 5–6 times larger than the Kβ excitation factors. The measured excitation factors were compared only with theoretical calculated ones since there are no other experimental reports for the present elements in the literature. The present experimental values of Kα and Kβ excitation factors are in satisfactory agreement with the theoretical results.

Measurement of Li X-ray fluorescence production cross sections and intensity ratios of some elements at 59.54 keV

The Li (i = l, α, β, γ) X-ray production cross section and Lα/Ll, Lα/Lβ, Lα/Lγ, Ll/Lβ, Ll/Lγ, and Lβ/Lγ intensity ratio values for Yb, Ta, W, Hg, Tl, Pb, Bi, Th, and U have been determined using an excitation geometry at 59.54 keV incident photon energy. The measurements were performed using an Am-241 annular radioactive source and a high resolution Si(Li) detector. The experimental results of Li X-ray production cross sections and intensity ratios were compared with three different theoretical results and other available experimental results in the literature. Reasonable agreement is typically observed between the present and theoretical results.

Proton induced L1, L2, L3-sub-shell X-ray production cross sections of Hf and Au

Experimental data for proton induced X-ray production cross sections of L-sub-shells of Hf and Au were obtained, in order to contribute to the existing data sets and to support refinements of the ECPSSR theory. X-ray emissions of mono-elemental 10nm films of Hf and Au were excited with 0.7–1.5MeV protons. The measured L-line spectra were fitted assuming Gaussian shapes and constraining peak positions and line widths. The transition energy values used to establish peak positions were based on values proposed in the literature, while the line widths were matched to the detector resolution, obtained independently. The intensity of each line was obtained from the adjusted areas, without the use of emission rates. The line intensities were summed in α, β, γ, and ℓ groups to validate the measurements by comparison with existing data, and in L1, L2, L3-sub-shells for comparison with ECPSSR-UA theory. Ratios of the emission rates of lines of the same sub-shell were obtained and compared with the data from the literature.

K-shell X-ray production cross sections of Ni induced by protons, alpha-particles, and He+

The proton, alpha-particle, and He+ induced X-ray emissions of Ni were measured on mono-elemental thin films in order to obtain the K-shell X-ray production cross section in the energy range of 0.7–2.0MeV for protons, 4.0–6.5MeV for alpha-particles, and 3.0–4.0MeV for He+. The proton-induced X-ray production cross section for Ni agreed well with the theoretical values, endorsing the quality of the measurements. The X-ray production cross section induced with alpha-particles is in good agreement with ECPSSR theory in the complete range of energies, while for He+ that quantity is systematically below. Kβ/Kα ratios were evaluated and compared with experimental and theoretical values.

L shell fluorescence yields and total ionization and x-ray production cross sections for elements with 40≤Z≤92

Abstract Existing experimental compilation (till 2014) for a wide range of elements (40≤Z≤92) by proton impact (up to 10.0 MeV) is used to deduce empirical ionization and x-ray production cross sections. The reliability of the obtained cross sections is then exploited to derive new values of L shell average fluorescence yield. This was based on the fact that ratio of ionization to x-ray production cross sections is independent of the excitation energy of proton ranging from 0.02 to 10.0 MeV, for a given element. The obtained values are compared with earlier theoretical and experimental results, where a good agreement is observed for all elements under investigation.

Proton induced K X-ray production cross sections of the elements Al, Si, Ti, Fe, and Ni in the 0.7–2.0 MeV energy range

Proton induced K-shell ionization cross sections were obtained for the elements Al, Si, Ti, Fe, and Ni in the 0.7–2.0MeV energy range. The accuracy of these fundamental parameters is essential for PIXE analysis and the data in the literature present a considerable spread, mainly for Al and Si. The values obtained for Ti, Fe and Ni are compatible with the current theories and the experimental results reported in the literature. However, Al and Si cross sections present important differences from theoretical and experimental data. We propose values for the fluorescent yields of Al and Si that are compatible with recent results and can be incorporated in the computations of K X-ray production cross sections.

Ionization cross sections of the L subshells of Au by 50 to 100 keV electron impact

We have measured the Lα, Lβ, , , L, and Lη x-ray production cross sections of Au by 50–100 keV electron impact. From this experimental information we derived the L1, L2 and L3 subshell ionization cross sections with a novel analysis procedure that is based on an overdetermined system of equations and achieve the estimates by the least-squares method. The uncertainties in the atomic relaxation parameters needed to transform the x-ray intensities to ionization cross sections impose a lower limit to the relative standard deviations of the L subshell ionization cross sections, which is found to be 5–10% depending on the selected set of relaxation parameters. Our experimental results are in reasonable accord with most of the measurements carried out by other authors, and they agree with the predictions of the semi-relativistic distorted-wave Born approximation.

Corrigendum to “Alloying effect on K X-ray intensity ratio and production cross section values of Zn and Cr in Zn–Cr alloys” [Radiat. Phys. Chem. 87 (2013) 6–15

a Department of Physics, Faculty of Sciences, Karadeniz Technical University, Trabzon 61080, Turkey b Bordj-Bou-Arreridj University Center, Institute of Science and Technology, 34000 Algeria c Ferhat Abbas University, Faculty of Science, Physics Department, Laboratory LESIMS, Setif 19000, Algeria d Department of Physics, Faculty of Arts and Sciences, Mustafa Kemal University, Hatay 31040, Turkey e Department of Metallurgical and Materials Engineering, Faculty of Technology, Mustafa Kemal University, Hatay 31040, Turkey f Department of Energy Systems Engineering, Faculty of Technology, Mustafa Kemal University, Hatay 31040, Turkey

Measurements of K shell absorption jump factors and jump ratios using EDXRF technique

In the present work, the K-shell absorption jump factors and jump ratios for 30 elements between Ti (Z = 22) and Er (Z = 68) were measured by energy dispersive X-ray fluorescence (EDXRF) technique. The jump factors and jump ratios for these elements were determined by measuring the K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to-Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using an Am-241 radioactive point source and a Si (Li) detector in direct excitation and transmission experimental geometry. The results for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature.

Measurements of K -shell X-ray production cross-sections and fluorescence yields for some elements in the atomic number range 28≤ Z ≤40

Abstract K shell X-ray production cross-sections ( σ K α and σ K β ) have been measured for some elements in the atomic number range 28≤Z≤40. Measurements have been carried out at 16.896 keV excitation energy using secondary source. K X-rays emitted by samples have been counted by a Si(Li) detector with 160 eV resolution at 5.9 keV. The values of K-shell fluorescence yields ( ω K ) have been evaluated for the same elements. The results obtained for K X-ray production cross-sections and fluorescence yields have been compared with the theoretically calculated values and other available semiempirical values.

Empirical M X-ray production cross sections for heavy elements by proton impact within Z-dependence analysis

New empirical M-shell X-ray production cross sections have been deduced by introducing the dependence of the universal trend of the experimental data on the atomic number of the target, noted as "Z-dependence" for semiempirical cross sections in our previous work. For this effect, the updated experimental data (from 1980 to 2009) are used to calculate the empirical cross sections for heavy elements with 60 $\le $ Z $\le $ 90 by proton impact. Finally, a comparison is made between the deduced results and other earlier works.

L-X-ray production cross sections by positrons

The L-shell X-ray production cross sections for Ag, In and Sn by positron impact have been calculated with two methods based on classical mechanics, i.e. the binary-encounter approximation and the classical trajectory Monte Carlo method. The results are compared with the experimental data and quantum mechanical calculations. We found that both classical treatments describe the inner-shell ionization processes by positron impact reasonably well.

Determination of K shell absorption jump factors and jump ratios of 3d transition metals by measuring K shell fluorescence parameters

Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring K-shell absorption jump factors and jump ratios for Ti, Cr, Fe, Co, Ni and Cu elements. The jump factors and jump ratios for these elements were determined by measuring K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to-Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation and transmission experimental geometry. The measured values for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature.