Ionization of Atomic Hydrogen by Low Energy Antiprotons

The cross section for electron removal or ionization of the simplest atom (hydrogen or its isotope deuterium), by antiprotons, is of 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 process is a signature of the ionization process. The antiproton hydrogen collision system is therefore an ideal system against which to test our theoretical understanding of the few-body Coulomb physics involved in ionization.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 proceessing of materials, particularly to effect 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.Our understanding of the ionization mechanism in such a simple collision system should enable an important step forward in current theoretical models.