Sound propagation and relaxation processes in the isotropic phase of cholesteryl miristate

The propagation and absorption of high-frequency sound in the isotropic phase of cholesteryl miristate is studied in a wide frequency range using the data of both Brillouin spectroscopy and acoustooptic measurements. The parameters of the relaxation process associated with the volume viscosity relaxation are calculated using the experimental data on the velocity and absorption of sound.     

Effective equation of nonlinear pulse evolution in a randomly anisotropic medium

Propagation of a light pulse through a weakly inhomogeneous optical fiber is analyzed. The non-linear envelope equation describing the evolution of polarized pulses is determined by statistical properties of inhomogeneities in the optical fiber. The isotropic Manakov system of equations is shown to be applicable in the presence of high-frequency small-scale defects in the fiber. In the presence of only large-scale inhomogeneities, the signal dynamics are described by an anisotropic system of equations.     

Observation of latent coherent effects in randomized systems

Coherent interference effects of the following three types are experimentally discovered in disordered (randomized) systems: (i) Josephson behavior of the HTSC polycrystal BaKBiO in the phase-separated state; (ii) oscillations of bismuth film resistance, which are periodic in “direct” magnetic field; and (iii) mesoscopic oscillations of the resistance in the course of film growth. In the first case, the method for detecting the “latent” nonstationary Josephson effect is substantiated by the frequency modulation method for microwave radiation, while in the other two cases, simple models are proposed to explain the nature of coherent oscillations of the resistance. The analogy between the observed oscillations and the Josephson effect in randomized systems is discussed.     

New data on the ternary fission of 252Cf from the Gammasphere facility

Ternary fission of ²⁵²Cf was studied at Gammasphere using eight ΔE×E particle telescopes. Helium, beryllium, boron, and carbon light charged particles (LCPs) emitted with kinetic energy more than 9, 21, 26, and 32 MeV, respectively, were identified. The 3368-keV γ transition from the first 2⁺ excited state in ¹⁰Be was found and the population probability ratio N(2⁺)/N(0⁺) = 0.160 ± 0.025 was estimated. No evidence was found for 3368-keV γ rays emitted from a triple molecular state. For the first time, charge distributions are obtained for ternary fission fragments emitted with helium, beryllium, and carbon LCPs.     

Isotopic effect in the width of a giant dipole resonance in light nuclei

An isotopic effect in the widths of giant dipole resonances is established on the basis of an analysis of the latest systematics of photoabsorption cross sections for nuclei containing 12 to 65 nucleons. This effect arises owing to isospin splitting of a giant resonance and is enhanced by its configuration splitting.     

Elasticity and inelasticity of biomorphic silicon carbide ceramics

The effect of the vibration strain amplitude on the Young modulus and ultrasonic absorption (internal friction) in biomorphic SiC ceramics is investigated in the temperature range 116–296 K. The biomorphic SiC ceramics is prepared through pyrolysis of eucalyptus with subsequent infiltration of silicon. It is demonstrated that the vibration loading of samples in air and under vacuum is accompanied by a number of unexpected effects. The behavior of the studied ceramics is governed by at least two mechanisms, which, to a large extent, are responsible for the elastic and inelastic properties of the material. One mechanism is associated with the adsorption-desorption of environmental molecules (hypothetically, owing to the presence of pores and residual carbon), and the other mechanism involves microplastic deformation due to the motion of dislocations or other (similar) structural units.     

Nanocrystalline nature of high-symmetry Ce<Superscript>4+</Superscript>-Eu<Superscript>3+</Superscript> centers in silica gel glasses

The spectral-luminescent properties of silica gel glasses coactivated by Ce⁴⁺ and Eu³⁺ ions are investigated. The structure of the glasses is studied using x-ray powder diffraction and small-angle neutron scattering. The inference is drawn that Ce⁴⁺-Eu³⁺ centers with high-symmetry Eu(III) oxo complexes, which are formed in the glasses, have nanocrystalline nature. These centers are characterized by a weak vibronic interaction of Eu³⁺ ions with the matrix. The size of nanocrystallites formed under the synthesis conditions and at coactivator concentrations used is approximately equal to 10 nm.     

Effect of laser erosion on the copper and zinc concentrations in the surface layer of brass

A REMMA 102 scanning electron microscope equipped with semiconductor and wave spectrometers is applied to measure the copper and zinc concentrations in the surface layers of an M161 brass sample and the same sample subjected to a focused laser radiation. The results are compared with the results obtained with an MS3101 laser mass spectrometer having a laser-plasma ion source. The laser-assisted erosion of the surface layer in the brass is shown to significantly change the copper and zinc concentrations. It is found that, when the craters produced by laser pulses on the initial surface do not overlap, the copper and zinc contents in the laser-induced plasma correspond to their contents in the sample.     

Calculation of the ion transverse velocity distribution function under ion cyclotron resonance heating

The ion transverse velocity distribution functions and the fraction η of ions heated above a certain energy W ₁ are calculated as applied to the ion cyclotron resonance heating method of isotope separation. It is assumed that the longitudinal ion velocity distribution in a plasma source is nonequilibrium. Under high heating temperatures, the averaged ion transverse velocity distribution becomes essentially nonequilibrium and exhibits two maxima. The ion heating efficiency η is calculated for W ₁=40 eV and various values of the parameter p=λ/L, where λ is the wavelength of the electric field of an antenna and L is the heating zone extension. The relative contributions of the time-of-flight and Doppler broadenings are evaluated.     

On the magnetic dipole absorption of electromagnetic radiation by a fine conducting particle

The cross section of absorption of electromagnetic radiation by a fine spherical conducting particle is estimated in terms of the classical kinetic theory of electrical conduction. The mixed diffuse-specular mechanism of charge carrier reflection from the sample boundary is considered. A correlation between the coefficient of specular reflection and the absorption cross section at different temperatures is analyzed.