Peculiarities of Cherenkov and Transition Radiation in a Finite-Size Absorbing Medium

Russian Physics Journal - Based on the equations of macroscopic electrodynamics, the spectral-angular characteristics of electromagnetic radiation are considered, which is generated during the...     

X-Ray Cherenkov Radiation in an Absorbing Medium with Finite Dimensions

Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - The spectral-angular characteristics of the electromagnetic radiation produced during the propagation of fast charged...     

Book reviews

Prospects for Fusion Power, Edited by S. 0. Dean, Pergamon Press, $29.30.

The Detection of Fissionable Materials by Nondestructive Means by R. Sher (Stanford University) and S. Untermyer II (National Nuclear Corporation), pp. 298. Price : $US49.00.     

On polarization energy loss of ions

The effect of correlations of ion charge fluctuations on polarization energy loss in the passage through condensed media are considered. It is shown that the correlation contribution to the energy loss is reduced to the replacement of the equilibrium charge by a certain effective one depending on the ion velocity and root-mean-square charge fluctuations as the ion velocity is larger than the Bohr velocity. Otherwise the correlations of the ion charge fluctuations play a significant role in polarization loss that cannot be described in terms of the equilibrium or effective charge.     

Modeling of neutral-atom scattering at the surface of a crystal for the case of grazing incidence

The features of the angular distributions of accelerated neutral atoms at grazing angles of incidence on the Al(001) surface are studied using the mathematical modeling method. The interaction of accelerated atoms with crystal-lattice atoms and the electronic properties and atomic structure of the Al(001) surface are calculated using the electron-density-functional method. The angular distributions of scattered atoms are modeled by taking into account their interaction with several atomic layers in the crystal lattice and atomic displacements during thermal oscillations. The influence of crystal surface-layer relaxation on rainbow scattering, i.e., the difference between the distances of planes on the surface and in the volume, is established. The possibilities of using the effect of rainbow scattering to study the structural features of a crystal surface are discussed.     

Properties of the oxygen sublattice structure of YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−<Emphasis Type="Italic">x</Emphasis></Subscript> crystal studied by ion channeling

Properties of the oxygen sublattice structure of the YBa₂Cu₃O_{7 ?x} crystal are studied using the diffusion model of ion channeling. The angular dependence of the elastic resonance scattering of helium ions on oxygen nuclei along the 〈001〉 direction is measured at an ion energy of 3.055 MeV. Steps are observed in the scattering yield at an angle of about 0.4°. The best fit of the calculated angular dependence of elastic resonance scattering to the experimental data is attained under the assumption that the oxygen rows contain vacancies corresponding to a fraction (not exceeding 20%) of the disordered oxygen atoms, which are randomly distributed in the plane normal to the 〈001〉 direction, and that the oxygen atoms in the rows are displaced from their equilibrium positions in a direction normal to the 〈001〉 axis.     

“Emergency” channeling radiation due to collisions with point defects

Conditions and causes of a new effect of “emergency” channeling radiation due to collision with point defects have been obtained. Numerical calculations have shown that this effect may be considerable.     

Dynamic Interaction of Nitrogen Atoms with the Surface of an Aluminum Crystal

Russian Physics Journal - A possibility of reconstructing the ion-atom dynamic interaction potential from the dependence of the rainbow scattering angle of nitrogen atoms under the conditions of...