Lγ X-ray Production Cross Sections Research Articles

Measurements of L-subshell x-ray production cross sections and M-shell x-ray yields of Pb by low-energy electron impact using the thick-target method

The Lα, Lβ, and Lγ x-ray production cross sections and M-shell x-ray yields by 5–29 keV electrons bombarding a thick Pb target were measured. The effects of multiple-scattered electrons, from the bremsstrahlung and other secondary particles within the thick sample were corrected using the Monte Carlo simulations. The experimental results are compared with the DWBA predictions of Bote et al., and also with the experimental data from the literature. The results indicate that the measurements of the production cross sections for the L subshells of the elements with higher atomic numbers using the thick-target method are feasible and reliable.

L-shell X-ray production cross sections of Ce, Nd, Sm, Eu, Gd, and Dy by impact of 14N2+ ions with energies between 7.0 MeV and 10.5 MeV

L-shell X-ray production cross sections from the lanthanoid elements Ce, Nd, Sm, Eu, Gd, and Dy, induced by the impact of 14N2+ ions with energies in the interval 7.0MeV to 10.5MeV (0.50MeV/μ to 0.75MeV/μ), were measured and then compared with theoretical calculations obtained with the ECPSSR model with exact limits of integration (eCPSSR) and related corrections. These include the electron capture by the incoming ion and multiple ionizations of higher shells. Data from this work were contrasted with previously published L X-ray production cross sections for 14N2+ ion impact. As with other ions, a universal behavior is found when Lα and Lγ X-ray production cross sections are plotted as a function of reduced velocity parameters. The agreement with theoretical predictions was very good when the corrections were applied to the eCPSSR model.

News

News

Lα, Lβ, and Lγ x-ray production cross sections for heavy elements by electron impact

We have calculated Lα, Lβ, and Lγ x-ray production cross sections by the impact of electrons on Hf, W, Re, Os, Au, and Pb. We used the distorted-wave Born approximation to calculate ionization cross sections of the L subshells of these atoms. Atomic relaxation parameters were taken from the literature. The theoretical predictions are compared with published experimental information. Good agreement is generally found except for Re, where the measured cross sections are systematically lower than the theoretical estimates by around 20 %. The observed discrepancy may be due to the relatively large uncertainty in the determination of the sample thickness.

New data base for Lα, Lβ, Lγ x-ray production by protons, new empirical fits, extraction of L-subshell ionization cross sections with various atomic parameters, and their comparison with the ECPSSR theory and its modifications: a recommendation for reliable choice of atomic parameters and ionization theory for PIXE analysis

Tables of L-shell and L-subshell x-ray production cross sections by protons from 1994 are updated, and the so constructed data base is fitted to formulas for empirical Lα, Lβ, Lγ x-ray production cross sections. Based on these fits, empirical L-subshell ionization cross sections are generated with various sets of atomic parameters with and without alteration for multiple ionizations. The extracted ionization cross sections are compared with the predictions of the ECPSSR theory and it modifications. Based on comparisons with different choice of the atomic parameters and theories, we will recommend an optimal combination of the atomic parameters and ionization theory for a reliable input in PIXE applications software.

L-Shell Ionization Cross Section Measurements of Dysprosiumand Samarium by Low-Energy Electron Impact

The Lα, Lβ and Lγ x-rayproduction cross sections of Dy and Sm by electron impact are measuredat energies from near threshold to tens of keV. In the experiments,thin targets with thick substrates are used. Meanwhile, the electrontransport bipartition model is used to eliminate the influence ofelectrons reflected from the thick substrates on measurements. Themeasured x-ray production cross sections are also compared with thetheoretical predictions by Gryzinski and McGuire.

Measurements of Coster–Kronig enhancement factors of some elements in the atomic number range 66 ≤ Z ≤ 72

AbstractThe Lι, Lα, Lβ and Lγ x‐ray production cross‐sections in four elements with Z ranging from 66 to 72 at seven different energies in the interval 8.265–11.730 keV were measured. Experimental measurements were carried out on a few elemental samples to examine the effect of Coster–Kronig transitions on fluorescence cross‐sections for the L x‐ray line using an Si(Li) detector system with an energy resolution of 160 eV at 5.96 keV x‐ray energy. Absolute values of L x‐ray cross‐sections were calculated with incorporation of the enhancement due to the Coster–Kronig effect for these elements. The measured enhancement factors are smaller than predicted by theory. Copyright © 2003 John Wiley & Sons, Ltd.

L-subshell fluorescence yields [formula omitted] and ω3) for elements in the atomic range 55⩽ Z⩽68 with a Si(Li) detector

Lα, Lβ and Lγ X-ray production cross-sections of 55 Cs , 56 Ba , 57 La , 58 Ce , 59 Pr , 60 Nd , 62 Sm , 65 Tb , 66 Dy , 67 Ho and 68 Er have been measured by using a Si(Li) detector coupled to a model 1024 computerized multi-channel analyzer. The L-subshell X-ray fluorescence yields ω 1, ω 2 and ω 3 have been derived, using the experimental Lα, Lβ and Lγ X-ray production cross-sections, theoretical L-subshell photoionization cross-sections, Coster-Kronig transition probabilities, vacancy transfer probabilities and fractional X-ray emission rates. The experimental data have been compared with the literature experimental data, theoretical predictions based on Dirac–Hartree–Slater wave functions and semiempirical compilations.

Angular dependence of Lx-ray production cross sections in seven elements from Yb to Ptat a photon energy of 59.5 keV

The Lℓ, Lα, Lβ and Lγ x-rayproduction cross sections of Pt, Re, W, Ta, Hf, Lu and Yb havebeen measured using an incident photon energy of 59.5 keV atan angular range of 40-130°. The measurements wereperformed using a 241Am radioisotope as the photon source anda detection system with a Si(Li) detector. Althoughdifferential cross sections for Lβ and Lγ x-rayswere found to be angle independent within experimental error,those for the Lℓ and Lα x-rays were found to be angledependent. As previously reported this confirms theangular dependence of photon-induced Lℓ and Lαx-ray production cross sections. Furthermore the present resultsalso confirm the theoretical predictions of Flügge et al (Flügge S, Melhorn W and Schmidt V 1972 Phys. Rev. Lett. 29 7) and Jacobs (Jacobs V L 1972 J. Phys. B: At. Mol. Phys.5 2257). However, our experimental results are contrary to the results reported byMehta et al (Mehta D, Puri S, Singh N, Garg M L andTrehan P N 1999 Phys. Rev. A 59 2723). Integral cross sections forthe production of Lℓ, Lα, Lβ and Lγ x-rays are also deduced inthis paper and are found to be in good agreement withtheoretical values.

Measurement of Lℓ, Lα, Lβ and Lγ X-ray Production Cross Sections and Average L Shell Fluorescence Yields for Elements in the Atomic Range 70 ≤ Z ≤ 92 at 59.54 keV

Lℓ, Lα, Lβ, and Lγ x-ray production cross sections have been measured for the elements Yb, Hf, W, Os, Hg, Tl, Pb, Th and U for 59.54 keV γ-rays from a 100 mCi 241Am filtered source. The average L-shell fluorescence yields have been deduced using the experimentally measured cross section values and the theoretical photoionization cross sections. The experimental results for x-ray production cross sections (Lℓ, Lα, Lβ, Lγ) and average L-shell fluorescence yields are compared with experimental values, theoretical prediction and semiempirical fits. The agreements are reasonably good.

L[formula omitted], Lα, Lβ and Lγ X-ray production cross-sections and yields of some selected elements between caesium and erbium following ionization by 59.54 keV γ rays

L l , Lα, Lβ and Lγ X-ray production cross-sections were measured in elements from Cs to Er following ionization for 59.54 keV γ-rays from an 241Am point source. The measured values are compared with theoretical predictions estimated using subshell photoionization cross-sections, fluorescence yields, Coster–Kronig transition probabilities, K to L i subshell vacancy transfer probabilities and radiative decay rates. Average L-shell fluorescence yields were deduced from present measured total L X-ray production cross-sections, theoretical K and L photoionization cross-sections and K to L vacancy transfer probabilities. The obtained results for L X-ray production cross-sections and average L-shell fluorescence yields are compared with recent experimental values, theoretical predictions, and semiempirical fits.

Measurement of l-shell X-ray production cross-sections of Yb bombarded by 250–400 keV protons

Abstract The L-shell X-ray production cross-sections, viz. σLα, σLβ and σLγ of Yb have been measured by means of proton-induced ionization in the energy region of 250–400 keV. The thick target X-ray yields have been measured using a HPGe detector. The theoretical calculations for the Lα, Lβ and Lγ X-ray production cross-sections have been performed taking the L-subshell ionization cross-sections on the basis of ECPSSR theory and using the theoretical X-ray emission rates, sub-shell flourescence yields and Coster-Kronig transition probabilities. The comparison of the experimental results with the theoretically calculated values shows a fairly good agreement.