Channeling of positrons

Pedersen, Malthe Jessen; Andersen, J. U.; Augustyniak, W.

doi:10.1080/00337577208231120

Cited by 29 publications

(4 citation statements)

References 5 publications

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“…41 together with the comparable energy-scaled result for protons. Pedersen et al (1972) The potentials that steer the incident beam are usually modeled by a continuum approximation, using cylindrically symmetric string potentials for axial channeling and two-dimensional planar potentials for planar channeling. low-symmetry planes.…”

Section: Positron Channelingmentioning

confidence: 99%

Interaction of positron beams with surfaces, thin films, and interfaces

1988

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Recent advances in the study of solid surfaces and thin films using variable-energy positron beams are reviewed. In the first part the authors discuss the process of positron moderation and technical aspects of positron beam production and application. The second part is (roughly) organized in sections that apply to increasing time scales appropriate to the positron-solid interaction. These are (a) first encounter and scattering effects, (b) energy loss and stopping profiles,

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Section: Positron Channelingmentioning

confidence: 99%

Interaction of positron beams with surfaces, thin films, and interfaces

1988

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“…The quantum description of radiation emission using wave functions as seen in Refs. [6,27,28] is valid when χ 1, because spin effects and recoil are neglected, and when ξ 1, because the magnetic field in the particle's rest frame is neglected and only the dipole matrix element is calculated. In the present paper we treat the problem from the laboratory frame, and the field can therefore be described solely by an electrostatic potential ϕ(y).…”

Section: Wave Functionsmentioning

confidence: 99%

“…Such an approach can be found, for example, in Refs. [6,27,28]. For higher particle energies, the theory relies on the semiclassical operator method by Baier et al [29], which then includes the effects of spin and photon recoil, but neglects the quantization of the transverse motion.…”

Section: Introductionmentioning

confidence: 99%

Complete treatment of single-photon emission in planar channeling

Wistisen

Piazza

2019

Phys. Rev. D

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Approximate solutions of the Dirac equation are found for ultrarelativistic particles moving in a periodic potential, which depends only on one coordinate, transverse to the largest component of the momentum of the incoming particle. As an example we employ these solutions to calculate the radiation emission of positrons and electrons trapped in the planar potential found between the (110) planes in Silicon. This allows us to compare with the semi-classical method of Baier, Katkov and Strakhovenko, which includes the effect of spin and photon recoil, but neglects the quantization of the transverse motion. For high-energy electrons, the high-energy part of the angularly integrated photon energy spectrum calculated with the found wave functions differs from the corresponding one calculated with the semi-classical method. However, for lower particle energies it is found that the angularly integrated emission energy spectra obtained via the semi-classical method is in fairly good agreement with the full quantum calculation except that the positions of the harmonic peaks in photon energy and the photon emission angles are shifted.

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“…This condition is necessarily to fulfil in order to establish a special kind of the particle motion, typically an undulating one, associated with the crystal lattice. In other words, under these conditions, the motion of a particle in an aligned crystal can be described within the quantum-mechanical principles in the form of a bound motion defined by a potential well [16,17]. The potential well, in both shape and depth, is determined by the averaged potential of the crystal lattice in its dependence on the crystal orientation, planar or axial.…”

Section: Introductionmentioning

confidence: 99%

Surface Channeling of Charged and Neutral Beams in Capillary Guides

Dabagov

Dik

2022

QuBS

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In this review work, the passage of charged and neutral beams through dielectric capillary guides is described from a uniform point of view of beams channeling in capillaries. The motion of beams into the hollow channels formed by the inner walls of capillaries is mainly determined by multiple small-angle scattering (reflection) and can be described in the approximation of surface channeling. It is shown that the surface interaction potential in the case of micro- and nano-capillaries is actually conditioned by the curvature of the reflecting surface. After presenting the analysis of previously performed studies on X-rays propagation into capillaries, which is valid for thermal neutrons, too, the surface channeling formalism is also developed for charged particle beams, in particular, moving in curved cylindrical capillaries. Alternative theories explaining experimental results on the beams passage through capillaries are based on simple thermodynamic estimates, on various diffusion models, and on the results of direct numerical simulations as well. Our work is the first attempt to explain the effective guiding of a charged beam by a capillary from the general standpoint of quantum mechanics, which made it possible to analytically explore the interaction potential for surface channeling. It is established that, depending on the characteristics of a projectile and a dielectric forming the channel, the interaction potential can be either repulsive or attractive; the limiting values of the potential function for the corresponding cases are determined. It has been demonstrated that the surface channeling behaviour can help in explaining the efficient capillary guiding for radiations and beams.

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Channeling of positrons

Cited by 29 publications

References 5 publications

Interaction of positron beams with surfaces, thin films, and interfaces

Interaction of positron beams with surfaces, thin films, and interfaces

Complete treatment of single-photon emission in planar channeling

Surface Channeling of Charged and Neutral Beams in Capillary Guides

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