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Deep Minima and Vortices for Positronium Formation in Positron-Hydrogen and Positron-Helium Collisions

This dissertation work is a study of positronium formation for positron-hydrogen and positron-helium collisions in the Ore gap (the energy region between the threshold for ground-state positronium formation and the first excitation level of the target atom) using variational K-matrices. We have fitted the K-matrices using multichannel effective range theories and using polynomials. Using the variational K-matrices and their fits, we have located zeros in the positronium-formation scattering amplitude and corresponding deep minima in the positronium-formation differential cross section. The zeros are related to the vortices in the extended velocity field associated with the positronium-formation scattering amplitude. For positron-hydrogen collisions, we have found two zeros in the positronium-formation scattering amplitude, and corresponding deep minima in the positronium-formation differential cross section, while we have obtained a zero in the positronium-formation scattering amplitude for positron-helium collisions. We have connected the zeros in the positronium-formation scattering amplitude to vortices in the extended velocity fields. Our work shows that vortices can occur for charge exchange in atomic collisions.

Identiferoai:union.ndltd.org:unt.edu/info:ark/67531/metadc1808421
Date05 1900
CreatorsAlrowaily, Albandari Wanes
ContributorsQuintanilla, Sandra, Van Reeth, Peter, Littler, Chris, Ordonez, Carlos, Rostovtsev, Yuri
PublisherUniversity of North Texas
Source SetsUniversity of North Texas
LanguageEnglish
Detected LanguageEnglish
TypeThesis or Dissertation
Formatxix, 154 pages, Text
RightsPublic, Alrowaily, Albandari Wanes, Copyright, Copyright is held by the author, unless otherwise noted. All rights Reserved.

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