Plane wave born calculations of K-shell ionization at low velocities

Hippler, R.

doi:10.1016/0375-9601(90)90828-c

Cited by 90 publications

(87 citation statements)

References 14 publications

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“…This correction gives positron ionisation cross sections that are smaller than those of electrons near the ionisation threshold, in qualitative agreement with available experimental data (see, e.g., Hippler, 1990;Schneider et al, 1993). Fig.…”

Section: Ionisation Of Inner Shellssupporting

confidence: 89%

Radial Secondary Electron Dose Profiles and Biological Effects in Light-Ion Beams Based on Analytical and Monte Carlo Calculations using Distorted Wave Cross Sections

et al. 2008

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Section: Ionisation Of Inner Shellssupporting

confidence: 89%

Radial Secondary Electron Dose Profiles and Biological Effects in Light-Ion Beams Based on Analytical and Monte Carlo Calculations using Distorted Wave Cross Sections

et al. 2008

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“…Near the ionization threshold, however, the PWBA is not adequate because it neglects the distortion caused by the atomic field on the wave function of the projectile and it also disregards electron exchange. Various semiempirical modifications to the PWBA have been proposed to account for these effects [1,2]. A more rigorous approach is to use the distorted-wave Born approximation (DWBA), in which the initial and final projectile wave functions include the distortion caused by the atomic field and, which also allows the description of exchange effects in a consistent way [3].…”

Section: Introductionmentioning

confidence: 99%

Measurements of absoluteK-shell ionization cross sections andL-shell x-ray production cross sections of Ge by electron impact

2004

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Results from measurements of absolute K-shell ionization cross sections and L␣ x-ray production cross sections of Ge by impact of electrons with kinetic energies ranging from the ionization threshold up to 40 keV are presented. The cross sections were obtained by measuring K␣ and L␣ x-ray intensities emitted from ultrathin Ge films deposited onto self-supporting carbon backing films. Recorded x-ray intensities were converted to absolute cross sections by using estimated values of the sample thicknesses, the number of incident electrons, and the detector efficiency. Experimental data are compared with the results of widely used simple analytical formulas, with calculated cross sections obtained from the plane-wave and distorted-wave Born approximations and with experimental data from the literature.

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“…We show that the departure from the prediction of PWBA observed for Kand L-shell ionization by electron and positron impact [7][8] is mainly due to two effects: (i) the projectile-target nucleus interaction (Coulomb-effect, C), and (ii) electron exchange between the incident and the bound electron (exchange effect, Ex). The measured ratio increases with decreasing projectile energy; this result is in fair agreement with our present calculations and can be explained by the Coulomb effect which is most important at small WI.…”

Section: Resultsmentioning

confidence: 73%

“…For a quantitative analysis, reliable cross sections for impact ionization are required. Calculated cross sections are frequently based on first order perturbation theories (for example, plane-wave-Born approximation (PWBA) [7][8]), which provide reliable cross sections for sufficiently "fast" collisions. These theories predict total cross sections which are independent of the sign of the projectile,s charge.…”

Section: Inner Shell Ionizationmentioning

confidence: 99%

Energy-Loss of Positrons in Foils

Schneider¹,

Tobehn²,

Rückert³

et al. 1993

Acta Phys. Pol. A

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The Giessen slow positron source TEPOS delivers intense beams in the energy range between some eV and 6 keV; with postacceleration up to 80 keV. Results for remoderation are described shortly. Further the energy--losses of positrons with incident energy of 6-20 keV through thin aluminium foils were measured. Cross sections for K-and L-shell ionization of thin silver and gold targets by positron and electron impact have been determined at projectile energies of 30-70 keV. The experimental results are presented in detail; they are confirmed by calculations in plane-wave-Born approximation which include an electron exchange term and account for the deceleration or acceleration of the incident projectile in the nuclear field of the target atom.PACS numbers: 07.77.+p, 29.25.-t, 34.80.Dp Experimental Positron sourceAn intense source for low-energy positrons (TEPOS) with a magnetic transporting system has been provided at the Giessen 65 MeV pulsed electron linear accelerator (LINAC) at the Strahlenzentum of the University, and is described elsewhere in detail [1][2]. The source set-up consists of a vacuum chamber, containing the watercooled tungsten converter-bremstarget, and the tungsten moderator with a repeller plate. A solenoid system and different adequate Helmholtz coils transport the positrons to the experimental area. RemoderationTo improve the beam quality of our positron source TEPOS (smaller beam diameter and lower energy spread) we performed experiments with various remoderation arrangements in transmission mode using thin (1000 A) monocrystalline tungsten foils and different electrostatic positron extraction systems. At the end of the set-up a deflecting spherical condensor (with an adequate diaphragm) to analyze the energy of the positrons, and channel plates are installed.(3751

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Plane wave born calculations of K-shell ionization at low velocities

Cited by 90 publications

References 14 publications

Radial Secondary Electron Dose Profiles and Biological Effects in Light-Ion Beams Based on Analytical and Monte Carlo Calculations using Distorted Wave Cross Sections

Radial Secondary Electron Dose Profiles and Biological Effects in Light-Ion Beams Based on Analytical and Monte Carlo Calculations using Distorted Wave Cross Sections

Measurements of absoluteK-shell ionization cross sections andL-shell x-ray production cross sections of Ge by electron impact

Energy-Loss of Positrons in Foils

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