Ionization of Atomic Hydrogen by Low Energy Antiprotons

Lead Research Organisation: Queen's University of Belfast
Department Name: Sch of Mathematics and Physics


Ionization is an important process in astrophysical and technological plasmas and in the dissociation of molecules in the Earth's atmosphere. Technological plasmas are increasingly used in industrial processing of materials, particularly to affect their surface properties, and are widely used in the semiconductor industry. Energy from controlled plasma fusion of hydrogen isotopes presents us with the possibility of a 'clean' energy source to replace fossil fuels and to alleviate global warming resulting from carbon dioxide emissions from current generation power stations.The cross section for electron removal or ionization of the simplest atom (hydrogen, or its isotope deuterium) by antiprotons is currently of considerable interest. This is the simplest collision system for testing theory with only one active electron and, since the antiproton cannot capture an electron, the detection of a hydrogen ion in coincidence with an antiproton after the collision is a signature of the ionization process. We will measure the cross sections for ionization of atomic hydrogen by antiproton impact at low energies, in a range never before accessed experimentally. Our understanding of the ionization mechanism in such a simple three-body system should enable an important step forward in current theoretical models.A firm theoretical understanding of ionization is important to the applications mentioned above, as theory is often used to provide input to simulations and in the interpretation of observations in physical situations where dedicated experiments are difficult, or even impossible...

Planned Impact

The main impact of this work will be on the academic community studying few-body Coulomb physics, particularly as involved in ionization. The results are eagerly awaited by the atomic collisions theory community and we anticipate that some serious long-standing discrepancies will be resolved and that the Fermi-Teller theory will be tested for the first time. Since accurate modelling of the ionization process has applications in laboratory (including industrial) fusion and astrophysical plasmas, a knock-on effect will be felt in these communities via the development of improved theoretical models and diagnostics. The study will impact on the growing antihydrogen community who will benefit from the data obtained in the proposed work via the development of a more complete understanding of very low energy antiproton collisions.


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Description WE have provided benchmark data for atomic collision theory.
Exploitation Route these data will enable the further development of fundamental collision theory
Sectors Aerospace, Defence and Marine,Education

Description The data in the publication is being used by collision theorist to understand the fundamental process of ionisation in ion-atom ion-simple molecule collisions
First Year Of Impact 2004
Sector Aerospace, Defence and Marine,Education
Description Univ of Swansea 
Organisation Swansea University
Country United Kingdom 
Sector Academic/University 
PI Contribution We worked together with Professor Charlton at CERN on the experimental project on antiproton collisions.
Collaborator Contribution Professor Charlton made a positive contribution to both the operation of the experiment and the discussions of the physics involved
Impact Deatils of all publications have been listed.
Start Year 2006
Description University of Arhus 
Organisation Aarhus University
Country Denmark 
Sector Academic/University 
Start Year 2009
Description University of Tokyo 
Organisation University of Tokyo
Country Japan 
Sector Academic/University 
Start Year 2009