Crystal potential periodicity effects on the dynamics of fast charged particles and their emission of radiation

We present an overview of our comprehensive quantal theory of the dynamics of fast charged particles in crystals and of the radiation they emit. Unlike previous theoretical investigations in this field, ours takes account of the full three-dimensional periodicity of the crystal potential in all dynamical regimes of the particle motion through the crystal. We show that, contrary to prevailing assumptions, the periodicity of the crystal potential, both along the direction of propagation of the particle and transversely to it, give rise to important observable effects and cannot be ignored even for channeled particles. In particular, we show that channeled particles radiate via momentum transfer to the crystal in terms of reciprocal lattice vectors. Thus the spontaneous radiation spectrum predicted by our theory is much richer than what has been known hitherto.