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Feasibility study of resonant antiproton capture by ions and an open system approach to resonance decay
Stockholm University, Faculty of Science, Department of Physics. Atomfysik. (Teoretisk Atomfysik)
2008 (English)Licentiate thesis, monograph (Other academic)
Abstract [en]

The present thesis is based on two different projects. The first part deals with

resonant capture of antiprotons by electron excitation in highly charged hydrogenlike ions.

The search for this process was mentioned by an experimental group at the Max Planck Institute in

Heidelberg (Germany) as a possible future project at the Facility for Low Antiproton and

Ion Research (FLAIR) at the "Gesellschaft f\"ur Schwerionenforschung" (GSI) in Darmstadt (Germany),

which motivated the theoretical feasibility study presented in this thesis.

Illustrative calculations on the collision of antiprotons in the energy

region $E\approx 0.13-0.14\,{\rm keV}$ with hydrogenlike calcium Ca$^{19+}$ have been carried out

using an approach which is common in dielectronic recombination (DR) calculations, justified by the fact

that the process of

interest can formally be seen as the exotic analogon of DR where the incoming electron is replaced by

an antiproton.

In particular, we investigated the doubly excited resonant electron-antiproton states that can eventually be formed

in such a collision and estimated their positions as well as the rates of the possible decay channels. Based on this,

first approximate predictions for the cross section of resonant antiproton capture are made.

The second part of the thesis is devoted to resonances as well, but in quite a different context. Due to the coupling

to the continuum, a quantum system that contains resonances can be treated as an {\it open} quantum system. Such an approach,

however, is often heuristic to a certain extent, because the theoretical decription of the

dissipative interaction of an open system with its environment in many cases requires phenomenological constants that cannot

be determined from the first principles. To investigate whether such constants are connected to known parameters of a resonance

(its width, in particular), the unitary time evolution of a model quantum system within the Schr\"odinger equation is

compared to the non-unitary time evolution within the Lindblad master equation. For the chosen model potential, good agreement

was achieved and a relation between the resonance width and the phenomenological constants that appear in the

Lindblad-type equations of motion is suggested.

Place, publisher, year, edition, pages
2008. , 93 p.
National Category
Atom and Molecular Physics and Optics
URN: urn:nbn:se:su:diva-15057OAI: diva2:181577
Available from: 2008-11-19 Created: 2008-11-19Bibliographically approved

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