Magnetization reversal in amorphous gadolinium-cobalt films with a radial gradient of magnetic properties

The integral characteristics of magnetization switching in amorphous gadolinium-cobalt films with perpendicular anisotropy are studied by visualizing the domain structure and measuring magnetooptic hysteresis loops. The films have a radial gradient of magnetic properties that is due to a spatially nonuniform thermal field. Magnetization switching in those film areas where the domain wall motion depends only on the coercive force is simulated in simple terms. In a first approximation, local events of magnetization switching are shown to take place independently of each other and the net hysteresis loop can be represented as a sum of the local loops.     

On the accuracy of classical, semiclassical and quantum methods in collision line broadening calculations: Comparative analysis for C2H2-Ar, He systems

Accuracies of classical, semiclassical and quantum methods are comprehensively examined in calculations of impact line widths of C₂H₂ molecules perturbed by Ar and He. The field of comparative study covers both infrared absorption and Raman scattering lines of acetylene having rotational quantum number J=0-30 at temperatures 173 and 296 K. Calculations have been made by fully classical method and by three basic least approximate semiclassical methods, namely, Neilsen-Gordon (NG) method, peaking approximation (PA) and Smith-Giraud-Cooper (SGC) method. Most accurate ab initio potential energy surfaces (PES) of Yang et al. (1996) [21] and Mozsynski et al. (1995) [22] have been applied to model C₂H₂-Ar and C₂H₂-He interactions. The comparison has been made also with available experimental data and with the results of rigorous fully quantum-mechanical calculations within close coupling and coupled states approaches in identical conditions. Semiclassical methods are proved to be not so much accurate as it is generally believed since all they gave in the cases considered seriously underestimated results. The fundamental issue of the adequacy of simplified trajectories in collision broadening calculations is finally reasonably solved. In cases of C₂H₂-Ar and C₂H₂-He systems the use of the “exact” isotropic trajectories (i.e. driven only by the isotropic part of PES) is the main reason of failing of NG, PA and SGC methods. Thus the neglecting of back-influence of the RT exchange on the classical path is a principal defect of semiclassical methods. Finally, the application of simplified trajectories is recognized as inadequate and risky in broadening calculations for molecules having relatively small rotational constants when accurate ab initio PES are applied.     

Entropy considerations in numerical simulations of non-equilibrium rarefied flows

Non-equilibrium rarefied flows are encountered frequently in supersonic flight at high altitudes, vacuum technology and in microscale devices. Prediction of the onset of non-equilibrium is important for accurate numerical simulation of such flows. We formulate and apply the discrete version of Boltzmann’s H-theorem for analysis of non-equilibrium onset and accuracy of numerical modeling of rarefied gas flows. The numerical modeling approach is based on the deterministic solution of kinetic model equations. The numerical solution approach comprises the discrete velocity method in the velocity space and the finite volume method in the physical space with different numerical flux schemes: the first-order, the second-order minmod flux limiter and a third-order WENO schemes. The use of entropy considerations in rarefied flow simulations is illustrated for the normal shock, the Riemann and the two-dimensional shock tube problems. The entropy generation rate based on kinetic theory is shown to be a powerful indicator of the onset of non-equilibrium, accuracy of numerical solution as well as the compatibility of boundary conditions for both steady and unsteady problems.     

Features of the magnetic properties of Pd/Fe/Pd films and nanodisks

The magnetic properties of Pd/Fe/Pd films and nanodisks with diameter 600 nm fabricated by focused ion beam milling were investigated. A fourth-order anisotropy of magnetization reversal in nanodisk arrays was observed during the experiment. It was demonstrated that the anisotropy occurs due both to the breaking of symmetry of dipole-dipole interactions at array boundaries and to the initiation of inhomogeneous configurations of magnetization in nanodisks.     

An IC100 cyclotron based facility for producing nuclear filters and for scientific and applied research

The cyclotron IC-100 station, based on the Laboratory of Nuclear Reactions (JINR, Dubna, Russia), provides the industrial construction of nuclear filters. During modernization, the cyclotron was equipped with a superconducting ECR-ion source and an axial injection system. The specialized beam channel with a two coordinate scanning system and equipment for irradiating polymer films was installed in the implantation part of the station. High intensity heavy ion beams of Ne, Ar, Fe, Kr, Xe, I, and W have been accelerated to 1 MeV/nucleon energy. The investigation into irradiated crystals features and irradiation of different polymer films is provided. Also, a few thousands square meters of track films with holes in the wide range of densities were produced. The cyclotron-based station is capable of solving different kinds of scientific and applied problems as well. The text was submitted by the authors in English.     

Properties of multiplicity distributions in νA and\bar v A intersections atE_{\begin{array}{*{20}c} {( - )} \\ v \\ \end{array} }< 30GeV

We present data on the multiplicity structure of inclusive charged hadron production in charged current neutrino and antineutrino freon interactions in the energy range 3–30 GeV resulting from an experiment with the bubble chamber SKAT. Average multiplicities, dispersions and correlation coefficients are investigated. Furthermore, KNO-scaling is studied and average net charges are calculated in different kinematical regions. Our data are compared with results from \(\begin{array}{*{20}c} {( - )} \\ v \\ \end{array} \) -interactions on an isoscalar target of “free” nucleons to study the influence of nuclear effects.     

On the oscillation and asymptotic behavior of the solutions of a certain system of differential-functional equations of neutral type

Conditions for the oscillation of all solutions and for the existence of nonoscillatory solutions with polynomial growth at infinity are given for the system of differential-functional equations of neutral type

Extended transverse-momentum analysis for intermediate-energy heavy-ion collisions

An extension of the transverse-momentum analysis of Danielewicz and Odyniec is proposed. This extension involves a consideration of baryonic p_T-distribution widths in and out of the reaction plane. Calculations within one- and two-fluid mean-field models show that such an analysis allows us to extract more information on the nuclear equation of state and stopping power than the conventional one does. Different criteria for selecting collision events (i.e. sorting them out according to impact parameters) are also examined. Selections according to the baryonic multiplicity in the midrapidity region and the transversal-to-longitudinal energy ratio are found to be suitable for this purpose.