Ionization of Atomic Hydrogen and Helium by Low Energy Antiprotons

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


Experimental studies of collision processes, in which fundamental charged particles ionize simple atoms and molecules, provide the data necessary for our understanding of the many-body interaction and the development a theoretical description of this fundamental yet unsolved problem in collision dynamics. The ionization process plays an important role in astrophysical and technological plasmas and in the dissociation of molecules in the Earth's atmosphere. A comparison of single and multiple ionization of simple atomic and molecular targets by equi-velocity protons, electrons and their corresponding antiproton and positron antiparticles makes it possible to determine the effects of projectile mass and charge. The separation of 'pure' ionization from electron capture or transfer ionization processes can be studied in the special case of antiprotons colliding with light atoms. The absence of electron transfer is a significant simplification and the mass of the projectile enables straight-line trajectories models to be used.


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Indelicato P (2014) The Gbar project, or how does antimatter fall? in Hyperfine Interactions

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Capra A (2016) Limit on the electric charge of antihydrogen in Hyperfine Interactions

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Jonsell S (2016) The role of antihydrogen formation in the radial transport of antiprotons in positron plasmas in Journal of Physics B: Atomic, Molecular and Optical Physics

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Knudsen H (2009) On the double ionization of helium by very slow antiproton impact in Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

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Knudsen H (2008) Ionization of helium and argon by very slow antiproton impact. in Physical review letters

Description The total cross sections for single ionization of helium and single and double ionization of argon by antiproton impact have been measured in the kinetic energy range from 3 to 25 keV using a new technique for the creation of intense slow antiproton beams.
Exploitation Route The new data provide benchmark results for the development of advanced descriptions of atomic collisions and we show that they can be used to judge, for the first time, the validity of the many recent theories.
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 2008
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