Study of cross-sections for the K-shell ionization of atoms by electron and positron impact

Measurements of Lα, Lβ X-ray production cross sections of Bi by 17–40keV electron impact

“…The reason is maybe due to the fact that the spectral lines for the measurements of L-and higher-shell ionization cross-section data are more complicated than the K-shell data and the L-and highershell ionization cross sections are responsible for not only the Auger but also the Coster-Kronig (CK) transitions [8,9]. For the experimental data of K-shell ionization cross sections, An et al [18,19] systematically compared the experimental data of 24 elements from Z = 12 (C) to 47 (Ag) with the PWBA-C-Ex theory [2,3] and Luo and Joy's theory [20,21] as well as some empirical formulae. It can be seen that for the medium-Z elements the calculation results from these theoretical models and the empirical formulae were very close each other and in good agreement with the experimental K-shell ionization cross sections, but for lower-and higher-Z elements the calculation results from these theoretical models and the empirical formulae were obviously different.…”

Copper K-shell emission cross sections for laser–solid experiments

“…Above +1 MeV, the cross section starts to increase continually from a minimum Macroscopic K-shell emission cross sections for solid copper. Points are from measurements given by Liu et al, 9 Llovet et al, 10 and Zhou et al 11 Curves are from expressions given by Hombourger, 17 An et al, 22 Santos et al, 25 Haque et al's BELI model, 19 Haque et al's XCVTS model, 24 and Bote et al 14 that is roughly a factor of 2 below the initial peak for copper. The position of this minimum does not vary significantly with atomic number, and its depth decreases with increasing atomic number as the peak moves up toward it.…”

“…Such expressions have been used in modeling laser-solid experiments, which would have led to significant errors; 2E/m e v 2 exceeds 1.1 at only 34 keV and exceeds 2 at 0.32 MeV. We then considered 12 relativistic expressions, [14][15][16][17][18][19][20][21][22][23][24][25] and there are almost certainly more out there. Since this time, a minor modification of Santos et al's expression 25 has been published by Guerra et al 26 Only four expressions clearly failed to reproduce the measurements: Jakoby et al's 16 14 expression around the dip, and by Hombourger's 17 expression at higher energies.…”

“…(2) for the fluorescence yield, we find that there is a maximum in the K-shell emission cross section at an atomic number close to 21, which is scandium. Considering the atomic number density of solids in this region, the maximum macroscopic cross section should belong to titanium (22), which has been used in high-intensity laser-solid experiments almost as frequently as copper. Considering that the K-shell emission self-absorption depth is roughly proportional to the atomic number, increasing the thickness of the layer from which emission can be obtained and consequently total yield, we find that maximum yield occurs near 29, which is copper.…”

Relativistic Ionization of Hydrogen Atoms by Positron Impact

“…Particular attention has recently been given to positron impact ionization of atoms and molecules (Positron Physics-M. Charlton, J. Humberston (Cambridge, 2001)) [1]. Many theoretical and experimental works have been carried out for these processes [2][3][4][5][6][7][8][9][10].…”