Positron-impact ionization of hydrogen atoms

The ionization cross section of hydrogen atoms by positron impact has been calculated by using a distorted-wave polarized-orbital method. We have employed two models depending on the choice of the final-channel wave function, and the two sets of results differ dramatically. We have also found that below 100 eV the total positron-impact ionization cross section including positronium formation is appreciably larger than the corresponding results for electron-impact ionization.

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The triple differential cross section for the ionization of hydrogen atoms under electron impact

Canadian Journal of Physics ◽

10.1139/p84-131 ◽

1984 ◽

Vol 62 (10) ◽

pp. 968-972 ◽

Cited By ~ 3

Author(s):

A. S. Ghosh ◽

P. S. Mazumdar ◽

Madhumita Basu

Keyword(s):

Differential Cross Section ◽

Cross Section ◽

Reasonable Agreement ◽

Ionization Cross Section ◽

Orbital Method ◽

Distorted Wave ◽

Hydrogen Atoms ◽

Ionization Cross ◽

Triple Differential Cross Section ◽

Theoretical Predictions

The triple differential ionization cross section (TDCS) in electron–hydrogen scattering has been calculated using a distorted wave polarized orbital method. The present TDCS results at 100 and 113.6 eV are in reasonable agreement with the measured values of Weigold et al. and the theoretical predictions of Smith. Winters, and Bransden.

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A measurement of the electron impact ionization cross section of atomic hydrogen in the metastable 2S state

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1975.0069 ◽

1975 ◽

Vol 343 (1634) ◽

pp. 333-349 ◽

Cited By ~ 35

Keyword(s):

Electric Field ◽

Electron Energy ◽

Cross Section ◽

Cross Sections ◽

Ionization Cross Section ◽

Impact Ionization ◽

Weak Field ◽

Weak Electric Field ◽

Hydrogen Atoms ◽

Ionization Cross

The total ionization cross section for electrons colliding with metastable 2S atoms has been measured up to 500 eV electron energy by a crossed beam technique. A beam of fast hydrogen atoms, containing about 25% in the 2S state and the rest in the IS ground state, is formed by charge capture onto protons that are passed through a caesium vapour target. Protons emerging from the target are removed from the beam by deflexion in a weak electric field. Atoms formed by capture into long-lived, high quantum states are first ionized in a topographically suitable field and then removed by deflexion in the weak field. The signal arising from electron ionization of the 2S atoms is identified by quenching them in a pulsed electric field. Contributions from other sources of extraneous ionization are eliminated by modulated beam techniques. The cross sections are determined from absolute measurements of the beam fluxes, the geometry of the interaction region and the rate at which 2S atoms are ionized. The results show that as the electron energy is raised, the ionization cross section for 2S atoms rises to a maximum at about 4 times the ionization energy of the 2S state. This maximum, about 10 -15 cm 2 , is 13 times larger than th at of the IS atoms. Comparison with various theoretical determinations indicates th at best agreement is obtained with the Born approximation which includes exchange, but below 100eV the classical Monte Carlo approximation agrees equally well with observations.

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Positron-impact ionization of atomic hydrogen in the distorted-wave polarized-orbital method

Canadian Journal of Physics ◽

10.1139/p90-038 ◽

1990 ◽

Vol 68 (2) ◽

pp. 249-252 ◽

Cited By ~ 9

Author(s):

K. K. Mukherjee ◽

Keka Basu Choudhury ◽

N. Ranjit Singh ◽

P. S. Mazumdar ◽

S. Brajamani

Keyword(s):

Cross Sections ◽

Atomic Hydrogen ◽

Impact Ionization ◽

Theoretical Calculations ◽

Orbital Method ◽

Distorted Wave ◽

Positron Impact ◽

Positron Energy ◽

The Matrix ◽

Final Channel

Calculations are performed for the total cross sections for the positron-impact ionization of the ground state of atomic hydrogen, employing the distorted wave polarized orbital method. This explicitly takes into account the matrix elements arising from the distorted part of the target wave function and the effect of final-channel distortion in the incident-positron energy range 20.4–68 eV. The results are compared with available theoretical calculations.

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