Simulation of transport and relaxation of hot electrons in the near-surface layers of nanostructured and crystalline silicon dioxides

Computer simulation has been performed to investigate the transport and energy relaxation of photoelectrons in the near-surface layers of nanostructured and crystalline silicon dioxides in the presence and absence of an electric field. Calculations have shown that nanostructured samples have a shorter hot-electron thermalization time and exhibit weaker influence of an electric field on the electron energy relaxation process than the bulk crystal. The size effect calculated in terms of electron thermalization time is most pronounced at particle sizes less than 5 nm.     

The Long-Distance Asymptotics for the Correlation Function of the Third Spin Components in the XX0 Model with Interaction Through Two Sites

The XX0 chain in the external magnetic field directed along the z axis is discussed. The Hamiltonian describing the exchange interaction between two and four neighboring sites of the chain is constructed. An integral representation for the equal-time temperature correlation function of the third spin components is given. From the long-distance asymptotic of this correlation function, the correlation radius is calculated and its low-temperature behavior is studied. Bibliography: 11 titles.     

Luminescence Quenching in Magnesium-Doped Alumina Ceramics

Physics of the Solid State - The effect of magnesium impurity on luminescent properties of alumina ceramics sintered at high temperatures under vacuum is studied by pulsed cathodoluminescence,...     

Electrical breakdown and high-energy electron emission under dielectric charging

A Monte-Carlo calculation model for electron transport in crystalline dielectrics charged by irradiation is improved with allowance for impact ionization and cascading processes. The electron transport in SiO ₂ is simulated for high-strength electric fields. It is found that a breakdown in a dielectric can occur in the electric field strength range 11.5–12.5 MV/cm. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 52–58, March, 2008.     

Heavy ion linear accelerator with high-frequency quadrupole focusing

Based on results of works on the NICA/MPD (Joint Institute for Nuclear Research, Dubna) project, the possibility of designing a heavy ion linear accelerator with high-frequency quadrupole focusing both in the input part and in the main part of the accelerator is shown. Parameters of the linear ¹⁹⁷Au³¹⁺ ion accelerator are presented. Special attention is paid to technical questions of calculating, designing, manufacturing, and tuning the accelerator.     

Influence of disorder on superconductivity in non-magnetic rare-earth nickel borocarbides

The effect of substitutional disorder on the superconducting properties of YNi₂B₂C was studied by partially replacing yttrium and nickel by Lu and Pt, respectively. For the two series of (Y, Lu)Ni₂B₂C and Y(Ni, Pt)₂B₂C compounds, the upper critical field H _c2(T) and the specific heat c _p(T, H) in the superconducting mixed state have been investigated. Disorder is found to reduce several relevant quantities such as T _c, the upper critical field H _c2(0) at T=0 and a characteristic positive curvature of H _c2(T) observed for these compounds near T _c. The H _c2(T) data point to the clean limit for (Y, Lu) substitutions and to a transition to the quasi-dirty limit for (Ni, Pt) substitutions. The electronic specific heat contribution γ(H) exhibits significant deviations from the usual linear γ(H) law. These deviations reduce with growing substitutional disorder but remain even in the quasidirty limit which is reached in the Y(Ni_1−x , Pt _x )₂B₂C samples for x=0.1.