Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact
We investigate ionization of atomic hydrogen by electron- and positron-impact. We apply the Coulomb–Born (CB1) approximation, various modified CB1 approximations, the three body distorted wave (3DW) approximation, and the time-dependent close-coupling (TDCC) method to electron-impact ionization of h...
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2020-05-01
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| author | C. M. DeMars S. J. Ward J. Colgan S. Amami D. H. Madison |
| author_facet | C. M. DeMars S. J. Ward J. Colgan S. Amami D. H. Madison |
| author_sort | C. M. DeMars |
| collection | DOAJ |
| description | We investigate ionization of atomic hydrogen by electron- and positron-impact. We apply the Coulomb–Born (CB1) approximation, various modified CB1 approximations, the three body distorted wave (3DW) approximation, and the time-dependent close-coupling (TDCC) method to electron-impact ionization of hydrogen. For electron-impact ionization of hydrogen for an incident energy of approximately 76.45 eV, we obtain a deep minimum in the CB1 triply differential cross section (TDCS). However, the TDCC for 74.45 eV and the 3DW for 74.46 eV gave a dip in the TDCS. For positron-hydrogen ionization (breakup) we apply the CB1 approximation and a modified CB1 approximation. We obtain a deep minimum in the TDCS and a zero in the CB1 transition matrix element for an incident energy of 100 eV with a gun angle of <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mn>56.13</mn> <mo>°</mo> </msup> </mrow> </semantics> </math> </inline-formula>. Corresponding to a zero in the CB1 transition matrix element, there is a vortex in the velocity field associated with this element. For both electron- and positron-impact ionization of hydrogen the velocity field rotates in the same direction, which is anticlockwise. All calculations are performed for a doubly symmetric geometry; the electron-impact ionization is in-plane and the positron-impact ionization is out-of-plane. |
| first_indexed | 2024-03-10T19:31:39Z |
| format | Article |
| id | doaj.art-8c209baed5d04f1c8a04363183bfb364 |
| institution | Directory Open Access Journal |
| issn | 2218-2004 |
| language | English |
| last_indexed | 2024-03-10T19:31:39Z |
| publishDate | 2020-05-01 |
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| spelling | doaj.art-8c209baed5d04f1c8a04363183bfb3642023-11-20T02:06:39ZengMDPI AGAtoms2218-20042020-05-01822610.3390/atoms8020026Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron ImpactC. M. DeMars0S. J. Ward1J. Colgan2S. Amami3D. H. Madison4Department of Physics, University of North Texas, Denton, TX 76203, USADepartment of Physics, University of North Texas, Denton, TX 76203, USATheoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USADepartment of Physics, Missouri University of Science and Technology, Rolla, MI 65409, USADepartment of Physics, Missouri University of Science and Technology, Rolla, MI 65409, USAWe investigate ionization of atomic hydrogen by electron- and positron-impact. We apply the Coulomb–Born (CB1) approximation, various modified CB1 approximations, the three body distorted wave (3DW) approximation, and the time-dependent close-coupling (TDCC) method to electron-impact ionization of hydrogen. For electron-impact ionization of hydrogen for an incident energy of approximately 76.45 eV, we obtain a deep minimum in the CB1 triply differential cross section (TDCS). However, the TDCC for 74.45 eV and the 3DW for 74.46 eV gave a dip in the TDCS. For positron-hydrogen ionization (breakup) we apply the CB1 approximation and a modified CB1 approximation. We obtain a deep minimum in the TDCS and a zero in the CB1 transition matrix element for an incident energy of 100 eV with a gun angle of <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mn>56.13</mn> <mo>°</mo> </msup> </mrow> </semantics> </math> </inline-formula>. Corresponding to a zero in the CB1 transition matrix element, there is a vortex in the velocity field associated with this element. For both electron- and positron-impact ionization of hydrogen the velocity field rotates in the same direction, which is anticlockwise. All calculations are performed for a doubly symmetric geometry; the electron-impact ionization is in-plane and the positron-impact ionization is out-of-plane.https://www.mdpi.com/2218-2004/8/2/26electron-impact ionizationhydrogenpositron-impact ionizationvelocity fieldvortices |
| spellingShingle | C. M. DeMars S. J. Ward J. Colgan S. Amami D. H. Madison Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact Atoms electron-impact ionization hydrogen positron-impact ionization velocity field vortices |
| title | Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact |
| title_full | Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact |
| title_fullStr | Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact |
| title_full_unstemmed | Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact |
| title_short | Deep Minima in the Triply Differential Cross Section for Ionization of Atomic Hydrogen by Electron and Positron Impact |
| title_sort | deep minima in the triply differential cross section for ionization of atomic hydrogen by electron and positron impact |
| topic | electron-impact ionization hydrogen positron-impact ionization velocity field vortices |
| url | https://www.mdpi.com/2218-2004/8/2/26 |
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