Particle Channeling In Crystals Research Articles

Subbarrier interaction of channeling particles under the self-similar excitation of correlated states in a periodically deformed crystal

It has been shown that application of the periodic modulation of parabolic potential well parameters (in the case of charged particle channeling in crystals, i.e., periodic spatial modulation of the wall height of a potential well in the crystal channel) leads to the formation of the coherent channeling state in particles in this well. The formation of this state changes the interaction process between these particles and nuclei, and increases the barrier transparency by many times. For channeling this mode can be formed using, e.g., the longitudinal acoustic wave running along the channel axis. This wave changes the distance between nuclei and, accordingly, modulates the height of channel walls.

A mathematical theory of planar particle channeling in crystals

We use a simple two-phase averaging method for ODEs to characterize the class of energetic positively charged particle motions in the relativistic perfect crystal model that remain uniformly close to motions in Lindhard’s planar continuum model over long time intervals that grow with the particle energy. Our averaging method includes a generalization of a method of Besjes to quasiperiodic functions with truncated diophantine conditions, which allows us to exclude resonances due to low-order axial directions. Although our methods are mathematically rigorous, we believe the results are physically realistic, notably the estimates of the critical energy and of the initial directions for planar channeling.

Quantum Theory of Channeling in Deformed Crystals

AbstractA description of charged particle channeling in crystals with smooth strain fields of arbitrary nature and form is built within the framework of quantum mechanical approach based on the dynamical diffraction theory. General features of the solution obtained are discussed, and its particular applications to the studies of beam deflection by bent crystals and dechanneling on extended distortions are outlined, special attention is given to the influence of channel curvature variations. The effect of bulk retrapping into the channel is predicted and shown to play an important role for the case of alternating bending.