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Abstract
A review on the positron scattering from atoms and molecules is presented in this article. The focus on positron scattering studies is on the rise due to their presence in various fields and application of cross section data in such environments. Positron scattering is usually investigated using theoretical approaches that are similar to those for electron scattering, being its anti-particle. However, most experimental or theoretical studies are limited to the investigation of electron and positron scattering from inert gases, single electron systems and simple or symmetric molecules. Optical potential and polarized orbital approaches are the widely used methods for investigating positron scattering from atoms. Close coupling approach has also been used for scattering from atoms, but for lighter targets with low energy projectiles. The theoretical approaches have been quite successful in predicting cross sections and agree reasonably well with experimental measurements. The comparison is generally good for electrons for both elastic and inelastic scatterings cross sections, while spin polarization has been critical due to its sensitive perturbing interaction. Positron scattering cross sections show relatively less features than that of electron scattering. The features of positron impact elastic scattering have been consistent with experiment, while total cross section requires significant improvement. For scattering from molecules, utilization of both spherical complex optical potential and R-matrix methods have proved to be efficient in predicting cross sections in their respective energy ranges. The results obtained shows reasonable comparison with most of the existing data, wherever available. In the present article we illustrate these findings with a list of comprehensive references to data sources, albeit not exhaustive.
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Shipman M, Armitage S, Beale J, Brawley SJ, Fayer SE, Garner AJ, Leslie DE, Van Reeth P, Laricchia G. Absolute Differential Positronium-Formation Cross Sections. PHYSICAL REVIEW LETTERS 2015; 115:033401. [PMID: 26230792 DOI: 10.1103/physrevlett.115.033401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Indexed: 06/04/2023]
Abstract
The first absolute experimental determinations of the differential cross sections for the formation of ground-state positronium are presented for He, Ar, H2, and CO2 near 0°. Results are compared with available theories. The ratio of the differential and integrated cross sections for the targets exposes the higher propensity for forward emission of positronium formed from He and H2.
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Affiliation(s)
- M Shipman
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S Armitage
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - J Beale
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S J Brawley
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S E Fayer
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - A J Garner
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D E Leslie
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - P Van Reeth
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - G Laricchia
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Coleman PG, Cheesman N, Lowry ER. Coupling between positron-atom scattering channels above the first inelastic threshold. PHYSICAL REVIEW LETTERS 2009; 102:173201. [PMID: 19518780 DOI: 10.1103/physrevlett.102.173201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 02/24/2009] [Indexed: 05/27/2023]
Abstract
Experimentally determined cross sections for the elastic scattering of positrons by argon and xenon atoms have been found to exhibit a steplike increase at the first inelastic threshold energy--i.e., that for positronium formation. Rather than supporting the existence of a cusplike behavior predicted theoretically, this feature, which is more pronounced for xenon, suggests the existence of an intermediate virtual positronium state which enhances the elastic interaction probability.
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Affiliation(s)
- P G Coleman
- Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
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Ashley P, Moxom J, Laricchia G. Near-Threshold Ionization of He and H2 by Positron Impact. PHYSICAL REVIEW LETTERS 1996; 77:1250-1253. [PMID: 10063029 DOI: 10.1103/physrevlett.77.1250] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Falke T, Raith W, Weber M. Observation of structure in differential transfer ionization of argon atoms by positrons. PHYSICAL REVIEW LETTERS 1995; 75:3418-3421. [PMID: 10059581 DOI: 10.1103/physrevlett.75.3418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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