Single ionization by positron impact

1996 ◽  
Vol 74 (7-8) ◽  
pp. 367-372 ◽  
Author(s):  
J. Moxom ◽  
P. Ashley ◽  
G. Laricchia
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Positron Impact ◽  
Ionization Cross ◽  
Positron Scattering ◽  
Direct Ionization ◽  
Low Energies ◽  
Ionization Cross Sections ◽  
Impact Energies ◽  
Existing Data

The single direct ionization cross sections for positron scattering [Formula: see text] on He, Ar, Kr, and H2 were measured and compared with existing data and the corresponding cross sections for electron impact [Formula: see text]. At most impact energies the present data for He and H2 are in reasonable accord with other measurements and, in the case of He, with some of the available calculations. At low energies, [Formula: see text] is found to increase more slowly than [Formula: see text], probably due to the importance of Ps formation in this energy range.

Ionization in collisions between 30–1000 keV antiprotons and atomic hydrogen

1996 ◽  
Vol 74 (7-8) ◽  
pp. 490-495 ◽  
Author(s):  
K. Paludan ◽  
H. Knudsen ◽  
U. Mikkelsen ◽  
M. Charlton ◽  
K. Kirsebom ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
Theoretical Calculations ◽  
Published Data ◽  
Ionization Cross ◽  
Ionization Cross Sections ◽  
Impact Energies ◽  
Theoretical Results

Recently published data for impact of antiprotons in the energy range 30–1000 keV on atomic hydrogen are compared with analogous proton, electron, and positron measurements, and it is found that the ionization cross sections of atomic hydrogen follow the same pattern as similar cross sections obtained on He and H2 targets, in accordance with the general phenomenological description of single ionization that has developed over the last decade. Further comparisons are made with various recent and advanced theoretical calculations for antiproton ionization of atomic hydrogen. These theoretical results agree well with the data obtained, but for lower impact energies the different methods do not, despite the simplicity of the system, agree on predicting even the form of the cross section.

K-, L-, and M-shell ionization of atoms by electron and positron impact

1996 ◽  
Vol 74 (7-8) ◽  
pp. 376-383 ◽  
Author(s):  
S. P. Khare ◽  
J. M. Wadehra
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Positron Impact ◽  
Electrons And Positrons ◽  
Virtual Photons ◽  
Plane Wave Born Approximation ◽  
Ionization Cross Sections ◽  
Impact Energies ◽  
Shell Ionization ◽  
Good Agreement

The plane-wave Born approximation with Coulomb, relativistic, and exchange corrections is employed to obtain the K-, L1-, L2-, L3-, and M-shell ionization cross sections of a number of atoms bombarded by electrons and positrons in the energy range varying from the threshold of ionization to 1 GeV. Transverse interaction of virtual photons with atoms is also included and it is found to be of great significance for impact energies greater than about 1 MeV. For K- and L-shell ionization, good agreement between the theoretical values and various experimental data for electron-impact cross sections is obtained. However, for the M shell, the theory overestimates the experimental cross sections. For positron impact the agreement between the present results and the limited experimental data is found to be quite satisfactory.

Doubly-differential ionization cross sections of positron impact on argon

1994 ◽  
Vol 89 (1) ◽  
pp. 133-140 ◽  
Author(s):  
A. Schmitt ◽  
U. Cerny ◽  
T. Falke ◽  
H. Möller ◽  
W. Raith ◽  
...  
Keyword(s):  
Cross Sections ◽  
Positron Impact ◽  
Ionization Cross ◽  
Ionization Cross Sections
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