arXiv subjects

Vadim K. Ivanov

Publications and source records attributed to Vadim K. Ivanov.

4 recordsLinked to original sources

arXiv2019

Channeling of electrons and positrons in straight and periodically bent diamond(110) crystals

In this paper we present the results of a systematic numerical analysis of the channeling properties of electrons and positrons in oriented straight and periodically bent diamond(110) crystals. We analyse dependence of the intensity of the radiation emitted on the projectile energy as well as on the bending amplitude. The analysis presented is based on the grounds of accurate numerical simulations of the channeling process. The simulation parameters, such as the crystal orientation, thickness and bending parameters of the crystals as well as the energy of the projectiles, were chosen to match those used in past and ongoing experiments. The peculiarities which appear in the radiation spectra are attributed to the interplay of various radiation mechanisms. The analysis performed can be used to predict and explain future experimental results.

physics.acc-ph↗

arXiv2018

Interplay and specific features of radiation mechanisms of electrons and positrons in crystalline undulators

We predict peculiar changes in spectral distributions of radiation emitted by ultra-relativistic positrons and electrons in periodically bent crystals with variation of the bending amplitude. It is shown that the changes, being sensitive to the projectile energy, manifest themselves differently for negatively and positively charged projectiles. We demonstrate that the features observed are due to the interplay of different radiation mechanisms occurring in periodically bent crystals. The observations are important for design, practical realization and channeling experiments with periodically bent crystals as the key element of the novel light sources. The analysis presented is based on the grounds of accurate numerical simulations of the channeling process.

physics.acc-ph↗

arXiv2011

Role of exchange interaction in self-consistent calculations of endohedral fullerenes

Results of the self-consistent calculation of electronic structure of endohedral fullerene Ar@C$_{60}$ within the Hartree-Fock and the local density approximations are presented. Hartree-Fock approximation is used for the self-consistent description for the first time. It is shown that the accurate account of the exchange interaction between all electrons of the compound leads to the significant modification of the atomic valent shell which causes the noticeable charge redistribution inside the endohedral compound.

physics.atm-clus↗

arXiv2009

Many-body theory for angular resolved photoelectron spectra of metal clusters

Angular resolved photoelectron spectra of metal clusters have been experimentally measured for the first time only recently. These measurements have been performed systematically for sodium clusters in a broad range of cluster sizes. This work attracted a lot of attention and was reported practically at all major international cluster conferences because it revealed a very non-trivial behavior of the angular anisotropy parameter with respect to photon energy and provided a method for probing the angular momentum character of the valence orbitals of free nanoclusters. Initial attempts to explain these observations within single particle approximations fail completely. In this Letter we present a consistent many-body theory for the description of angular resolved photoelectron spectra of metal clusters. Jellium model formalism is employed. Our calculations demonstrate the dominant role of the many-body effects in the formation of angular distributions of photoelectrons emitted from sodium clusters and are in a good agreement with experimental data reported in. The concrete comparison of theory and experiment has been performed for the photoionization of $Na_7^{-}$ and $Na_{19}^{-}$ anions being characterized by the entirely closed shells of delocalized electrons.

physics.atm-clus↗