Resonance capture of electrons and positrons in the axial channeling mode at a crystal surface

Abstract

The motion of channeled particles in a single crystal is determined by the continuous potential of the crystallographic axes. The transverse motion of particles in the axial channeling mode is characterized by a discrete energy spectrum. In this paper, the criteria for selection of the continuous potential and the conditions for quantization of the transverse energy for axially channeled particles are discussed, and the criterion for the resonance capture of particles in the axial channeling mode during particle entrance into a single crystal is formulated; it requires that the particle’s angular momentum with respect to the channel axis coincides with a quantity that is a multiple of Planck’s constant. The effect of resonance capture can be observed, for example, via an increase in the intensity of electromagnetic radiation of the beam of channeled particles in the optical range at frequencies corresponding to transitions between the allowed levels of transverse motion.