# Hannover 2010 – wissenschaftliches Programm

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# A: Fachverband Atomphysik

## A 26: Electron Scattering and Recombination / Interaction of Matter with Ions (with MO)

### A 26.7: Vortrag

### Freitag, 12. März 2010, 12:30–12:45, B 302

**Collisions of low-energy antiprotons with He atoms** — •Armin Lühr and Alejandro Saenz — Humboldt-Universität zu Berlin, Institut für Physik, Moderne Optik, Hausvogteiplatz 5-7, D-10117 Berlin

During the last two decades advances have been achieved in the understanding of antiproton (p) collisions with the simplest one- and two-electron atoms H and He. However, in the case of p + He experiment and theory did not agree for impact velocities below the mean electron velocity for more than a decade stimulating a vivid theoretical activity.

Theoretical investigations for collisions of p with helium atoms
in an energy range from 1 keV to 6 MeV have been performed. The He atom is
described with a full two-electron approach which was recently applied in
nonperturbative time-dependent calculations of p + H_{2} collisions
[1].
The scattering wave function is expanded in time-independent eigenstates of the
target. The impact-parameter method is employed to describe the collision
process.
The present results for excitation and ionization are compared to experimental
as well as theoretical data highlighting persisting inconsistencies among these
data. The influence of two-electron effects as well as of expansion parameters
on the outcome of the calculations is discussed.

[1] A. Lühr and A. Saenz, Phys. Rev. A **80**, (Rapid Communication) (2009)