Measurements Of K-shell Ionization Cross Sections Research Articles

Measurements of K-shell ionization cross-sections of S, Ca and Zn by 7–30 keV electron impact

The absolute K-shell ionization cross-sections of S, Ca and Zn by 7–30 keV electron impact have been measured. The targets were prepared by evaporating the compounds ZnS and CaF 2 to the thick pure carbon substrates. The effects of multiple scattering of electrons penetrating the target films, electrons reflected from the thick pure carbon substrates and Bremsstrahlung photons produced when incident electrons impacted on the targets are corrected by using Monte Carlo method. The uncertainties of our measured K-shell ionization cross-sections are, respectively, ∼13% for S, ∼15% for Ca and ∼12% for Zn. The experimental results were compared with some theoretical results and available experimental data from the literature. The experimental data for S K-shell ionization cross-sections by 7–30 keV electron impact are given here for the first time.

Thick-target method in the measurement of inner-shell ionization cross-sections by low-energy electron impact

In this paper, we have studied the thick-target method for the measurements of atomic inner-shell ionization cross-section or X-ray production cross-section by keV electron impact. We find that in the processes of electron impact on the thick targets, the ratios of the characteristic X-ray yields of photoelectric ionization by bremsstrahlung to the total characteristic X-ray yields are Z-dependent and shell-dependent, and the ratios also show the weak energy-dependence. In addition, in the lower incident energy region (i.e. U < 5–6), the contribution from the rediffusion effect and the secondary electrons can be negligible. In general, the thick-target method can be appropriately applied to the measurements of atomic inner-shell ionization cross-sections or X-ray production cross-sections by electron impact for low and medium Z elements in the lower incident electron energy (i.e. U < 5–6). The experimental accuracies by the thick-target method can reach to the level equivalent or superior to the accuracies of experimental data based on the thin-target method. This thick-target method has been applied to the measurement of K-shell ionization cross-sections of Ni element by electron impact in this paper.

Some recent progress on the measurement of K-shell ionization cross-sections of atoms by electron impact: Application to Ti and Cr elements

In this paper, we have taken some measures to improve the accuracy of our experimental data for K-shell ionization cross-sections by electron impact. These measures include (1) measurement of the thin target thickness with Rutherford backscattering spectroscopy and (2) detection efficiency calibration in the lower energy region using thick carbon target bremsstrahlung by electron impact and (3) electron reflection correction and electron mean track length correction based upon Monte Carlo method. These measures are applied to the measurement of K-shell ionization cross-sections of Ti and Cr elements from the threshold energies up to 26 keV. From the comparison with some theoretical models, empirical formulae and some previous experimental data, it is concluded that these measures taken in this paper are effective in the improvement of accuracy of experimental data. The present experimental data for Ti and Cr elements also clarify the discrepancies among some experimental data sets. In addition, these measures will also be very helpful in the measurement of K-shell ionization cross-sections for lower Z elements and in the measurement of L, M-shell ionization cross-sections for medium and higher Z elements.

Measurement of K-Shell Ionization CrossSections of Cr, Ni and Cu Atoms by 7.5-25 keV Electron Impact

The K-shell ionization cross sections of Cr, Ni and Cu elements by7.5-25 keV electron impact have been measured. The experimental data havealso been compared with the theoretical predictions of the Hippler andMayol-Salvat models. In general, it seems that the Mayol-Salvatmodel can provide a better description to our experimental data.