Single and Double Ionization of Helium by the Impact of Fast Charged Particles
A survey of the recent literature shows that paradoxes abound in electron- and ion-impact ionization of helium. For example, Schulz et al. [M. Schulz, R. Moshammer, D. Fischer, H. Kollmus, D.H. Madison, S. Jones, J. Ullrich, Nature 422 (2003) 48] found that first-Born and three-body distorted-wave (3DW) theories reproduced their data for single ionization of helium by very fast fully stripped carbon ions in the scattering plane, but not outside the scattering plane. For much slower impacting carbon ions, however, Madison et al. [D.H. Madison, D. Fischer, M. Foster, M. Schulz, R. Moshammer, S. Jones, J. Ullrich, Phys. Rev. Lett. 91 (2003) 253201] found good agreement between 3DW theory and experiment, even outside the scattering plane. This creates a dilemma, since distorted-wave perturbation theories are generally thought to improve with increasing, not decreasing, projectile speed! in this contribution, we will address these and other issues, and suggest possible ways of proceeding.
S. Jones et al., "Single and Double Ionization of Helium by the Impact of Fast Charged Particles," Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier, Dec 2005.
The definitive version is available at http://dx.doi.org/10.1016/j.nimb.2005.07.009
National Science Foundation (U.S.)
Keywords and Phrases
3DW; CDW; Cross-Section; Distorted Wave; Electron Impact; Ion Impact; Perturbation Theory; Collisions (Nuclear Physics); Ionization
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