Ionization of Atomic Hydrogen by Low Energy Antiprotons

Lead Research Organisation: Swansea University
Department Name: College of Science


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...


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Description Cross section for single, nondissociative ionization of molecular hydrogen for impact of antiprotons have been measured. We have found that the cross section which is proportional to the projectile velocity, which is quite unlike the behavior of corresponding atomic cross sections, and which has never previously been observed experimentally.
Exploitation Route The results obtained during this grant can be used to benchmark theories of antiproton-atomic collisions.
Sectors Other

Description Our findings have been used by many scientists to justify theoretical and experimental work in number of areas of basic physics. Organisations such as CERN and our institutions have used our work to promote their respective missions, and in the public understanding of science.
First Year Of Impact 2011
Sector Other
Impact Types Cultural

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