2γ and 3γ annihilation as calibration processes for high energy <Emphasis Type="Italic">e</Emphasis><Superscript>+</Superscript><Emphasis Type="Italic">e</Emphasis><Superscript>−</Superscript> colliders

Born differential cross sections and the lowest-order radiative correction to them are obtained in the kinematics of large-angle final photon emissions in high-energy electron-positron annihilation processes. Taking into account the possible emission of real soft and hard photons in collinear kinematics, we show the validity of the Drell-Yan form of the differential cross section with the nonsinglet structure functions of the initial leptons. The leading and next-to-leading contribution to the cross sections is obtained. The relevant numerical estimations are presented. The text was submitted by the authors in English.     

Analytical expression of transition form factors from discrete spectrum nS states to continuum states of hydrogen-like atoms

The new approach to calculation of transition form factors of hydrogen-like atoms is proposed. The explicit analytical expressions of transition form factors from arbitrary discrete states to continuum are obtained in terms of classical polynomials.     

Heat Transfer Processes in Multiferroics Bi1 – xHoxFeO3 (x = 0–0.20)

Physics of the Solid State - The thermal diffusivity and thermal conductivity of multiferroics Bi1&nbsp;–&nbsp;xHoxFeO3 (x = 0–0.20) have been studied in the high-temperature...     

Thermal diffusion and heat conductivity of BiFeO3 and Bi0.95La0.05FeO3 multiferroics at high temperatures

The thermal diffusion and heat conductivity of BiFeO₃ and Bi_0.95La_0.05FeO₃ multiferroics at high temperatures (300–1200 K) have been examined. The dominant mechanisms of phonon heat transfer in the region of ferroelectric and antiferromagnetic phase transitions have been revealed. The temperature dependence of the mean free path of phonons has been determined.     

Radiative corrections to the cross section for <Emphasis Type="Italic">e</Emphasis><Superscript>−</Superscript> + <Emphasis Type="Italic">p</Emphasis> → <Emphasis Type="Italic">v + n</Emphasis> and the crossed processes

The Born cross section and the radiative corrections to its lowest order are considered in the framework of QED with structureless nucleons including the emission of virtual and real photons. The result is generalized to take into account the radiative corrections in higher orders of the perturbation theory in the leading and next-to-leading logarithmic approximation. The crossing processes are considered in the leading approximation. The text was submitted by the authors in English.     

Phonon Scattering by Paramagnetic Ions of Europium and Samarium in Bismuth Ferrite

Physics of the Solid State - Temperature dependences of the thermal diffusivity and thermal conductivity in multiferroic materials BiFeO3, Bi0.90Sm0.10FeO3, and Bi0.90Eu0.10FeO3 were studied....     

Phase composition,microstructure, and thermophysical and dielectric properties of multiferroic Bi<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Dy<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>FeO<Subscript>3</Subscript>

An extensive study was performed to establish correlations between the crystal structure, the grain composition, and the dielectric and thermophysical properties of high-temperature multiferroics of the Bi_1?x Dy_x FeO₃ type (x = = 0.05–0.20). It is shown that a trade-off between the macroresponses in the materials is achieved at x = 0.10; this circumstance permits recommendation of the materials for practical use.     

Electron–positron pair production by linearly polarized photon in the nuclear field

Process of lepton pair production by polarized photon on nuclei can be used to measure the degree of linear polarization of high energy photon. The differential cross section and the analyzing power are calculated with taking into account higher powers of expansion in Zα. Pure Coulomb and screened potential are considered. The results are illustrated in terms of asymmetry. The screening effect as well as the effect of higher orders expansion in Zα   is shown to vanish in limit of pair emission angles exceeding m/ω$m/\omega$.     

Heat capacity and thermal diffusivity of heavy oil saturated rock materials at high temperatures

Journal of Thermal Analysis and Calorimetry - In this paper, a typical combined cycle power generation unit in Iran is simulated by a mathematical method in order to perform sensitivity analysis on...     

Heat capacity of nanostructured BaTiO3 ceramics

The temperature dependence of the heat capacity of nanostructured BaTiO₃ ceramics produced by the solid-phase method has been studied; before sintering, the synthesized charge is subjected to a severe action in Bridgman anvils in combination with shear deformation. It has been found that the ferroelectric transition is substantially smeared and the phase transition temperature decreases nonlinearly with increasing applied pressure. It has been shown that the defect structure plays a dominant role in the formation of physical properties of the ceramics.