Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 14: Ion Scattering II (with molecules and surfaces)
A 14.11: Vortrag
Donnerstag, 5. April 2001, 18:15–18:30, H1028
Transverse Cooling or Heating of Channeled Ions — •Florian Grüner1, Walter Assmann1, Sarkis Karamian2, and Jens-Ulrik Andersen3 — 1Sektion Physik, LMU München, Am Coulombwall 6, 85748 Garching, Germany — 2FLNR JINR, 141980 Dubna, Russian Federation — 3ACAP, Institute of Physics and Astronomy, Aarhus University, Aarhus C, Denmark DK 8000
According to the prevailing theory of channeling there should be no redistribution of an isotropic ion beam after transmission through a crystal. However, for not fully stripped ions we have measured a strong enhancement of the angular flux along crystal directions in certain cases as well as a strong reduction in the other cases. For a possible explanation of this new phenomenon an additional mechanism is proposed: cooling or heating of the transverse motion of channeled ions due to correlated charge exchange processes. Systematic measurements show a transition for most ions from cooling to heating in dependence of the ion energy.