  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
collides at relativistic speed with an intense x-ray laser beam of linear
polarization. The process proceeds nonlinearly due to simultaneous absorption
of a few laser photons. The capture of the electron into the ground state and
the $L$-shell is considered. The scaling of the total rate, the angular
distributions of the emitted positrons and a comparison to the competing
free-free channel are surveyed. Numerical results of pair production rates for
parameters for the planned x-ray free electron lasers at DESY and SLAC are
presented. We find that pair production with these laser facilities can become
observable in the near future.

Atomic Physics