Binary stopping theory for swift heavy ions

Citation
P. Sigmund et A. Schinner, Binary stopping theory for swift heavy ions, EUR PHY J D, 12(3), 2000, pp. 425-434
Citations number
26
Categorie Soggetti
Physics
Journal title
EUROPEAN PHYSICAL JOURNAL D
ISSN journal
14346060 → ACNP
Volume
12
Issue
3
Year of publication
2000
Pages
425 - 434
Database
ISI
SICI code
1434-6060(200012)12:3<425:BSTFSH>2.0.ZU;2-H
Abstract
The Bohr theory treats charged-particle stopping as a sequence of interacti ons with classical target electrons bound harmonically to their equilibrium positions. We demonstrate that equivalent results can be derived on the as sumption of free binary collisions governed by a suitable effective potenti al. This kind of mapping is rigorous in the limits of distant and close col lisions and therefore provides a tool to evaluate energy losses via binary- scattering theory. This model was developed with the aim of calculating sto pping forces for heavy ions at moderately high velocities, where a classica l-orbital calculation is typically superior to the Born approximation. The effective potential employed holds equally well for dressed as for stripped ions. Unlike the Bohr theory, the present evaluation avoids a formal divis ion into regimes of close and distant collisions that do not necessarily jo in smoothly. Moreover, no perturbation expansion is necessary. For these re asons the overall accuracy as well as the range of validity of the Bohr mod el are significantly enhanced. Extensive tests have been performed, includi ng comparisons with rigorous evaluations of the Z(1)(3) effect, with excell ent agreement even where such was not necessarily expected. Moreover, credi ble results have been obtained under conditions where the perturbation expa nsion shows poor convergence. A comparison with experimental data on O-Al i s encouraging, even though shell corrections and projectile excitation/ioni zation have not yet been incorporated and input has not yet been optimized.