Stopping mechanisms of negative heavy particles in gas targets

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 1996-07, Vol.115 (1), p.106-110
• Main Authors: Schiwietz, G., Wille, U., Díez Muiño, R., Fainstein, P.D., Grande, P.L.
• Format: Article
• Language: English
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/0168-583X(95)01521-3

The mechanisms responsible for the stopping of negatively charged, heavy particles in gas targets are discussed. Experimentally determined stopping powers of antiprotons and negative muons in He and H 2 targets are compared to the results of various theoretical calculations for the electronic and nuclear contributions to the stopping power. Target excitation and ionization via direct (first-order) electronic transitions are found to dominate the stopping in the range of high projectile velocities. Higher-order effects are revealed for intermediate velocities, while near-adiabatic dynamics is shown to prevail in the electronic stopping power at low velocities. The threshold behavior of the electronic stopping power in heavy rare-gas targets is discussed as a signature of the near-adiabatic stopping mechanism.