Bulletin of the Russian Academy of Sciences: Physics最新文献

Two-particle transverse momentum (P_T) correlations are investigated for proton–proton and deuteron–deuteron interactions at the center-of-mass energy of NN collisions of 10 GeV. The correlations between Λ-hyperons and anti-Λ-hyperons, K-, π-mesons and protons are calculated using the Geant4 FTF and Pythia 6.4 models. It is shown that P_T correlations between Λ-hyperons and strange particles in proton-proton interactions are stronger in the FTF model than in the Pythia model. Two-particle P_T correlations can be studied at the NICA SPD experiment. Studies of two-particle correlations can help clarify the mechanism of quark–gluon string fragmentation.

The spatial-frequency distributions of spin waves in a magnon crystal and their dispersion characteristics were experimentally investigated. In spite of the weak energy contrast of the crystal, the formation of a number of Brillouin zones and the existence of two types of wave nonreciprocity were detected. Of the two types, one is due to the asymmetry of dispersion dependences with respect to the direction of wave propagation, and the other is due to the difference between the spatial distributions of the waves propagating in opposite directions. The magnon crystal made it possible to detect and measure these types of nonreciprocity.

The authors study the parameters of the electromagnetic field when heating ferromagnetic steels in induction-resistive heating devices. New ways of calculating are obtained, and characteristics of electromagnetic fields in multilayer systems are determined. An estimate is made of the effect an internal copper layer of a heater, an air gap between layers, and the inductor current have on the parameters of the electromagnetic field.

The authors study the viscosity of liquids using a capillary viscometer of their own design. A value of viscosity is determined by the drop in pressure in the capillary, which makes it possible to study optically opaque liquids and carry out measurements in a magnetic field. A series of calibration experiments are carried out on liquids with known values of viscosity. The obtained dependences of the magnetoviscous effect in magnetic fluid samples with different structures and physical parameters are consistent with known theoretical and experimental data.

An experimental setup has been developed that allows generating local bipolar electric and magnetic fields in a superconducting sample to study its magnetic, electronic, and crystalline microstates in one cycle. It is shown that the application of a damped oscillating local magnetic field to a superconducting sample induces an exponentially damped travelling magnetic wave. With decreasing wavelength and increasing wave energy, as more of the oscillations of the mentioned local field incident on the sample and twins, the induced travelling wave covers more and more twin boundaries and interacts with the L, C, R loops formed on them. This, in turn, leads to a gradual increase in the magnetic flux density in the trap and the residual resonant frequency of the oscillating circuit.

A study is performed of the temperature dependences of the Hall coefficient, specific electrical resistance, and saturation magnetization for Fe₆₀Co₂₀Si₈B₁₂ and Fe₅₈Co₂₀Si₁₂B₁₀ alloys in amorphous and crystalline states. The relationship between these parameters is established and explained from the viewpoint of the theory of the anomalous Hall effect. Coefficients of the parameter of spin–orbital interaction are estimated on the basis of experimental data.

The elemental composition of a bottom sediments core from Lake Chasha (Southern Kamchatka) was studied using scanning X-ray fluorescence microanalysis with synchrotron radiation (µXRF-SR) with a spatial resolution of 1 mm. The data obtained were used to identify a tephra layer containing ash from the eruption of the Ksudach volcano in 1907. The rate of modern sedimentation in Lake Chasha was estimated and an age model was constructed covering the last century.

The authors study the effect of changes in the transparency of magnetic emulsions with deformable droplets of submicrometer size under the influence of magnetic field. The effect the orientation and strength of the magnetic field and the concentration of microdroplets have on the amplitude of transparency changes is revealed. Experimental data on the field dependence of the magneto-optical effect and its dependence on the angle of the magnetic field’s orientation are compared via calculations in an approximation of anomalous diffraction. The possibility of determining interphase tension in magnetic emulsions is analyzed by studying the relaxation of optical effects.

The features of the magnetic susceptibility of a magnetic fluid with a non-magnetic filler were experimentally studied. It was determined that the dependence of the magnetic susceptibility on the concentration of the non-magnetic filler has features. The explanation of the detected effects is based on the assumption of the influence of surface forces on the processes of relaxation of the magnetic moment of magnetic particles. It was also found that the dependences of the magnetic susceptibility of a magnetic fluid with a non-magnetic filler on the strength of the external magnetic field differ from similar dependences for the magnetic fluid without a filler.

Magnetoactive, also known as magnetorheological, elastomer is a composite material based on an elastic polymer filled with magnetic particles. The specifics of its deformation under the influence of magnetic fields have been the subject of this research. For instance, in non-homogeneous fields the degree of strain may reach hundreds of percent whereas magnetized samples containing high-coercivity (hard magnetic) components can suffer deformations occurring in a complex way. In addition to that, a sample responds to an external field with an increased roughness of its surface thus becoming more hydrophobic. The material also increases its stiffness by ten folds. These facts suggest that this elastomeric composite may be considered potentially useful for such areas as robotics and controllable damping units.