Evolution of the mössbauer spectra of ludwigite Co3 − x Fe x O2BO3 with substitution of iron for cobalt

A concentration series of single crystals of iron-cobalt ludwigites Co_{3 ? x} Fe _x O₂BO₃ (x = 0.0125, 0.025, 0.050, 0.10, 1.0) has been synthesized. The structure has been studied using X-ray diffraction and Mössbauer effect. A preferred occupation of nonequivalent crystallographic positions by iron in the ludwigite structure has been revealed. It has been found that the valence of substituting iron ions is three. It has been revealed that the structure of the γ-resonance spectrum of Co₂FeO₂BO₃ is complicated due to a composition disorder in the system.     

Measurement of the vector A y and tensor A yy , A xx , A xz analyzing powers for the dd → 3H p reaction at 200 MeV

The data on the vector A _y and tensor A _yy , A _xx , A _xz analyzing powers for the d → ³H p reaction have been obtained at the energy of the initial deuteron of 200MeV in the angular range of 0–95 degrees in the c.m.s. The calculations performed within one-nucleon exchange model with the use of the standard three-nucleon bound state wave functions fail to reproduce the data on the tensor analyzing powers.     

Directionality and maneuvering effects on a surface ship underwater acoustic signature

This work examines underwater source spectra of a small (560 tons, 40 m length), single-screw oceanographic vessel, focusing on directionality and effects of maneuvers. The measurements utilized a set of four, self-contained buoys with GPS positioning, each recording two calibrated hydrophones with effective acoustic bandwidth from 150 Hz to 5 kHz. In straight, constant-speed runs at speeds up to 6.2 m s(-1), the ship source spectra showed spectral levels in reasonable agreement with reference spectra. The broadband source level was observed to increase as approximately speed to the fourth power over the range of 2.6-6.1 m s(-1), partially biased at low speeds by nonpropulsion machinery signals. Source directionality patterns were extracted from variations in source spectra while the ship transited past the buoy field. The observed spectral source levels exhibited a broadside maximum, with bow and stern aspect reduced by approximately 12-9 dB, respectively, independent of frequency. An empirical model is proposed assuming that spectral source levels exhibit simultaneous variations in aspect angle, speed, and turn rate. After correction for source directionality and speed during turning maneuvers, an excess of up to 18 dB in one-third octave source levels was observed.     

Nonlinear Dynamics of Parametric Oscillations of Exciton–Polaritons in a Semiconductor Microcavity

Journal of Experimental and Theoretical Physics - The polariton dynamics in a microcavity in the parametric oscillator mode is studied when two pump polaritons turn into polaritons of signal and...     

Hybrid Plasma – Prospects for Application in Medicine and Biology

Russian Physics Journal - Different schemes and designs of generators of low-temperature hybrid plasma produced by simultaneous ionization of plasma-generating medium by an electron beam with...     

Data Acquisition and Diagnostic System for Prototype of PANDA Pellet Target

Physics of Atomic Nuclei - In the PANDA experiment of the FAIR project, it is proposed to use internal targets based on the hydrogen isotopes that provide a monodisperse regime of flow generation...     

Dynamics of Macroparticles in a Quasi-Two-Dimensional Dust–Plasma System under Directed External Action: Simulation Results

The action of the light pressure force on a bounded region of a 2D system of dust macroparticles is simulated using the molecular dynamics method. The dynamics of dust macroparticles in the quasi-2D structure (trajectories of particles, their mean square displacement, and kinetic energy) is analyzed for various values of the nonideality parameter and laser radiation power. It is shown that by varying the radiation power, it is possible to influence the self-diffusion processes and the value of chaotic velocity of particles. Analysis is performed for different initial values of the nonideality parameter of the unperturbed dust subsystem. It is found that the interparticle interaction results in an increase in the kinetic energy of particles in the region of action, as well as beyond it.     

Short-Lived Electron Excitations in FeTe1 –xSex as Revealed by Microwave Absorption

Journal of Experimental and Theoretical Physics - The Fe1 +yTe1 –xSex single crystals with the various Se/Te ratios were studied by the microwave absorption and direct current resistivity...     

Electron microscopy study of the microstructure of Ni–W substrate surface

The surface microstructure of Ni–W alloy tapes, which are used as substrates to form films of high-temperature superconductors and photovoltaic devices, has been studied. Several samples of a Ni₉₅W₅ tape (Evico) annealed under different conditions were analyzed using scanning electron microscopy, energy-dispersive X-ray microanalysis, electron diffraction, and electron energy-loss spectroscopy. NiWO₄ precipitates are found on the surface of annealed samples. The growth of precipitates at a temperature of 950°С is accompanied by the formation of pores on the surface or under an oxide film. Depressions with a wedge-shaped profile are found at the grain boundaries. Annealing in a reducing atmosphere using a specially prepared chamber allows one to form a surface free of nickel tungstate precipitates.