Hamburg 2009 – scientific programme

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A: Fachverband Atomphysik

A 4: Electron Scattering and Recombination

A 4.4: Talk

Monday, March 2, 2009, 15:30–15:45, VMP 6 HS-E

Electron-Positron Pair Creation in Relativistic Heavy Ion Collisions Described in a Molecular View — •Sven Augustin and Werner Scheid — Institut für Theoretische Physik, Justus Liebig Universität, Gießen, Deutschland

Previous calculations of cross sections for electron-positron pair production with electron capture into the target’s K shell in relativistic heavy nuclei scattering, for instance those done by Busic et al. [1], faced problems due to difficulties in defining the positron states in a two centre problem.

It is usually assumed that, after the collision, a positron is defined by a hole state in the negative continuum of the target ion. While this approach is true for a single ion, it is not if a second ion, i.e. the projectile, is present. This is indeed independent of their distance.

Thus a projection on the target’s negative continuum states causes a “double counting” of the positrons. It should be replaced by a projection on time dependent solutions of the Dirac equation with electromagnetic potentials of two separating ions.

Considering such a molecular-like setting we chose the description in a centre of mass frame rotating with the axis connecting target and projectile.

[1] O. Busic, N. Grün and W. Scheid, Phys. Rev. A70, 062707 (2004)