Channeling process in a bent crystal

Abstract

We have investigated the channeling process of charged particles in a bent crystal. Invoking simple assumptions we derive a criterion, which determines whether channeling occurs or not. We obtain the same criterion using the Dirac equation. It is shown that the centrifugal force acting on the particle in the berit crystal significantly alters the effective transverse potential. The cases of axial and planar channeling are considered. The channeling probability and the dechanneling probability due to tunneling of the particle under the barrier in the effective transverse potential are estimated. These probabilities depend on the specific scaling parameter characterizing the process. Using the quasiclassical theory of synchrotron radiation we have calculated the ~ontribut~ion to the radiation spectrum, which arises due to the curvature of the channel. This contribution beconies significant for TeV electrons or positrons. Some practical consequences of our results are briefly discussed.

Channeling of high-energy particles in bent crystals – Experiments at the CERN SPS

“…Analogously, one may ®x the maximum curvature by requiring that the bending angle, h, over one oscillation length in the channel, k w , must be smaller than the critical angle [25] …”

Coherent radiation of an ultrarelativistic charged particle channelled in a periodically bent crystal

“…In both cases the passage of an ultra-relativistic particle along the bent channel gives rise to the undulator radiation due to the curvature of the trajectory, provided that the projectile is trapped into the channel. The latter condition is subject to the general condition for the channeling process in a bent crystal [3,7], and can be fulfilled by a proper choice of projectile energy and maximal curvature of the channel, as described below. The advantage of the static channel is that its parameters are fixed and thus the projectile moves along the fixed trajectory as well.…”

“…The channeling process in a bent crystal takes place if the maximal centrifugal force in the channel, mγv 2 /R min (where R min is the minimum curvature radius of the bent channel) is less than the maximal interplanar field U ′ max [3,7]:…”

<title>Variation of deflection efficiency with nuclear charge for relativistic ions in bent crystals</title>

“…Analogously, one may fix the maximum curvature by requiring that the bending angle, θ, over one oscillation length in the channel, λ ψ , must be smaller than the critical angle 6 :…”