Keywords: multiphoton processes, photonuclear reactions, X–ray lasers, gamma–ray lasers, laser–assisted nuclear photoeffect, gauge invariance
Laser–assisted nuclear photoeffect re–examined
In a recent article of Dadi and Müller the modification of nuclear photoeffect due to intense laser field is discussed. The paper is criticised from the point of view of gauge invariance. The S–matrix element and the cross–section of the laser–assisted nuclear photoeffect are recalculated in a gauge invariant manner taking into account the effect of the Coulomb field of the remainder nucleus. The γ–photon energy dependence of the laser–free cross–section obtained in the plane wave and long–wavelength Coulomb–Volkov approximations are compared. The laser–assisted partial cross–sections with laser photon energy 2 keV and some different polarisation states of γ–photon of energy 3 MeV are numerically investigated.