Hamburg 2009 – scientific programme

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A: Fachverband Atomphysik

A 5: Atomic Systems in External Fields I

A 5.2: Talk

Monday, March 2, 2009, 17:00–17:15, VMP 6 HS-B

Laser-Induced Channeling of Bethe-Heitler Pairs — •Erik Lötstedt¹, Ulrich D. Jentschura^1,2, and Christoph H. Keitel¹ — ¹Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg — ²Department of Physics, Missouri University of Science and Technology, Rolla MO65409, USA

A high-energy photon colliding with a nuclear Coulomb field may decay into an electron-positron pair by the Bethe-Heitler process. We investigate the modification of this process by the addition of an assisting laser field [1]. For a subcritical laser field, the total cross section is almost unchanged compared to the laser-free case. In contrast, there is a drastic enhancement of the differential cross section in a certain direction of emission. The additional momentum transferred by the laser field serves to channel the produced pairs, so that they are preferentially ejected in a direction making a small angle with the propagation direction of the laser field. The laser-induced modification of the cross section can be understood by classical arguments.

[1] E. Lötstedt, U. D. Jentschura, and C. H. Keitel, Phys. Rev. Lett. 101, 203001 (2008).