A multi-channel wire gas electron multiplier

A novel and relatively simple method of production of electrodes for a multi-channel wire gas multiplier is developed. Two modifications of the multipliers have been tested: with a multiplication of electrons between two wire electrodes, MWGEM, and between a wire electrode and continuous anode, MWCAT. For both MWGEM and MWCAT detectors, filled with neon under pressure of 760 Torr and irradiated by beta-particles (Ni-63), the coefficient of proportional multiplication of electrons up to 10000 was obtained. For the MWGEM detector irradiated by alpha-particles (Pu-239), the coefficient of proportional multiplication of 300 was obtained. It is observed, that in contrast to the GEM detectors, produced by perforation of a metal-clad plastic foil, in a MWGEM the discharges do not destroy its electrodes even for the potentials above the threshold of discharges. The results on operation of the MWCAT filled with Ar, Ar+CH4 and Ar+1% Xe are also presented.Comment: 4 pages, 9 figure

Bose-Einstein condensation of semi-hard bosons in S=1 dimerized organic compound F2PNNNO

An analysis of the energy spectrum and the magnetization curve of two-dimensional organic antiferromagnet F2PNNNO with a spin-one dimerized structure shows that a behavior of the compound in an external magnetic field can be explained within a lattice boson model with an extended Pauli's exclusion principle, i.e. no more than two bosons per a dimer. The unusual magnetization curve observed experimentally in the compound reflects a sequence of phase transitions intrinsic for a lattice boson system with strong on-site and inter-site repulsions due to a tuning of magnon density by the applied magnetic field

Strong pair correlation in small metallic nanoclusters: the energy spectrum

The electronic shell structure in small metallic nanoclusters leads to high level degeneracy, which is strongly beneficial for the appearance of pair correlation. This results in a high value of Tc as well as in the appearance of a superconducting gap which causes a strong modification of the energy spectrum. The electronic energy spectrum becomes strongly temperature dependent. Consequently, specific experiments to demonstrate the presence of pair correlation can be proposed

Evaluation of clinical efficacy and safety of the Ilizarov apparatus for external fixation (literature review)

Purpose A retrospective analysis of clinical efficacy and safety of using the external fixation apparatus of G.A. Ilizarov's design. Materials and methods Analysis and evaluation of clinical data was performed using 107 literary sources. 4.200 clinical cases were studied to evaluate effectiveness, and 6.274 cases to assess safety. Results The analysis revealed a high clinical efficacy of using the Ilizarov apparatus for external fixation (various assemblies) in solving a wide range of practical problems in the field of traumatology and orthopedics. According to the results of the study, its high clinical treatment effectiveness was confirmed both on the use of the method in general (about 95 % of positive outcomes), and in specific nosological groups of patients (not lower than 90 % of positive outcomes). After having assessed the available data on the safety in the application of the Ilizarov apparatus for external fixation (various assemblies), we can conclude that the rates of adverse events, recorded in the literature analyzed, can be considered acceptable. Among all those events, the events classified as adverse effects of the product amounted to 17.03 % (5 ÷ 95 % CI: 16.11 ÷ 17.97 %). © Soldatov Yu.P., Stogov M.V., Ovchinnikov E.N., Gubin A.V., Gorodnova N.V., 2019. © 2019 Russian Ilizarov Scientific Center for Restorative Traumatology and Orthopaedics

Influence of spin structures and nesting on Fermi surface and a pseudogap anisotropy in t-t'-U Hubbard model

Influence of two type of spin structures on the form of the Fermi surface (FS) and a photoemission intensity map is studied for t-t'-U Hubbard model. Mean field calculations are done for the stripe phase and for the spiral spin structure. It is shown, that unlike a case of electron doping, the hole-doped models are unstable with respect to formation of such structures. The pseudogap anisotropies are different for h- and e- doping. In accordance with ARPES data for La2SrxCuO4 the stripe phase is characterized by quasi-one-dimensional segments of FS at k=(\pi,0) and by suppression of spectral weight in diagonal direction. It is shown that spiral structures display the polarisation anisotropy: different segments of FS correspond to electros with different spin polarisations.Comment: 12 pages, 4 figure

Mathematical modeling of the hydrodynamics of the bubble mode during the bottom blowing of the ladle furnace: Report III

The formation and motion of gas bubbles in the melt substantially affect the heat exchange and kinetics of chemical transformations when performing the fire refining of copper in the ladle furnace. The variation in the bubble velocity, as well as of the volume and surface of the moving gas bubble over the melt height, is considered in the presented mathematical model. © 2013 Allerton Press, Inc

Observation of magnetization reversal and negative magnetization in a double perovskite compound Sr2YbRuO6

Detailed magnetic properties of the compound Sr2YbRuO6 are presented here. The compound belongs to the family of double perovskites forming a monoclinic structure. Magnetization meas-urements reveal clear evidence for two components of magnetic ordering aligned opposite to each other, leading to a magnetization reversal, compensation temperature (T* = 34 K) and neg-ative magnetization at low temperatures and low magnetic fields. Heat capacity measurements corroborate the presence of two components in the magnetic ordering and a noticeable third anomaly at low temperatures (~15 K) which cannot be attributed the Schottky effect. The calcu-lated magnetic entropy is substantially lower than that expected for the ground states of the or-dered moments of Ru5+ and Yb3+, indicating the presence of large crystal field effects and/ or in-complete magnetic ordering and/or magnetic frustrations well above the magnetic ordering. An attempt is made to explain the magnetization reversal within the frameworks of available models.Comment: 15 pages text, 6 figures Journal-ref: J.Phys.:Condens.Matter 20(2008)23520

Surface effects in magnetic superconductors with a spiral magnetic structure

We consider a magnetic superconductor MS with a spiral magnetic structure. On the basis of generalized Eilenberger and Usadel equations we show that near the boundary of the MS with an insulator or vacuum the condensate (Gor'kov's) Green's functions are disturbed by boundary conditions and differ essentially from their values in the bulk. Corrections to the bulk quasiclassical Green's functions oscillate with the period of the magnetic spiral, $2\pi /Q$, and decay inside the superconductor over a length of the order $v/\pi T$ (ballistic limit) or $\sqrt{D/\pi T}$ (diffusive limit). We calculate the dc Josephson current in an MS/I/MS tunnel junction and show that the critical Josephson current differs substantially from that obtained with the help of the tunnel Hamiltonian method and bulk Green's functions.Comment: 10 pages 3 Figs; some misprints in fromulae corrected; submitted to Phys. Rev.