Item

Abstract

In the present work, the process of bound-free pair production of electrons and positrons in combined laser and Coulomb fields is investigated. It is assumed that an ion at relativistic speed collides with an intense x-ray laser beam. The process proceeds nonlinearly due to simultaneous absorption of several laser photons. The capture of the electron into the ground state and excited states is considered. The process probability is calculated in the framework of relativistic quantum mechanics. For this nonlinear process ordinary perturbation theory cannot be applied; instead the Strong-Field-Approximation is used,which neglects the influence of the Coulomb field on the positron. An analytical result for the amplitude is derived and numerical results of pair production rates for parameters for the planned x-ray laser at DESY are presented. The main outcome is that bound-free pair production has a sizeable probability and that it is comparable to the free-free reaction channel. Experimental observation of this process will become feasible in the near future.