Coherent excitation of relativistic heavy ions in a crystal

A periodic perturbation superimposed by collisions with periodically situated atoms of a crystal can coherently excite atomic or nuclear levels of the projectile travelling through the crystal. This effect is called resonant-coherent excitation (RCE). We report on some recent studies on atomic and nuclear RCE at relativistic energy. The fine structure of electronic levels of H-like relativistic heavy ions and their small perturbations by a crystal potential strongly affect the position, the shape and the width of a resonance in RCE in a crystal.