X-ray diffraction projection topography: Possibilities of the quantitative analysis of images of defects

We propose methods for obtaining quantitative data on the parameters of defects that are observed on projection topographs and determining the main parameters (the displacement-field value and character, the depth of the occurrence of defects under the input surface of the crystal, their spatial orientation, and other parameters) of defects from the characteristics of a diffraction image that is recorded on projection topographs. The possibility of determining the main characteristics of defects through the analysis of diffraction images on projection topographs is shown using the example of rectilinear dislocations introduced into a silicon monocrystal upon plastic bending.     

Characterization of continuously inhomogeneous media with arbitrary thermophysical profiles using photothermal technique

A numerical method of determining depth profile of thermo-physical parameters of an inhomogeneous sample is presented. By dividing the inhomogeneous material into number of sublayers in which each single layer can be treated as homogeneous, the thermal-wave field of the material is obtained based on recurrence relations of thermophysical parameters of each divided layer. A numerical algorithm of determining the depth profile of thermophysical parameters in the continuously inhomogeneous material under excitation of arbitrary beam size has been demonstrated by a polynomial fitting process for three arbitrary generated thermophysical profiles.     

Accurate determination of the spin Hamiltonian parameters for Mn2+ ions in cubic ZnS nanocrystals by multifrequency EPR spectra analysis

Accurate determination of the spin Hamiltonian (SH) parameters, describing the electron paramagnetic resonance (EPR) spectra of paramagnetic impurity ions in wide band gap semiconductor nanocrystals, is essential for determining their localization and quantum properties. Here we present a procedure, based on publicly available software, for determining with higher accuracy the SH parameters of isolated Mn(2+) impurity ions in small cubic ZnS nanocrystals. The procedure, which can be applied to other cubic II-VI semiconductor nanocrystals as well, is based on the analysis of both low and high frequency EPR spectra with line shape simulation and fitting computing programs, which include the hyperfine forbidden transitions and line broadening effects. The difficulties, limitations and errors which can affect the accuracy in determining some of the SH parameters are also discussed.     

Inverse relationships for ellipsometry of uniaxially anisotropic nanoscale dielectric films on isotropic materials

The possibilities of determining the optical parameters of uniaxially anisotropic non-absorbing ultrathin films on the basis of ellipsometric parameters are analyzed in the framework of a long-wavelength approximation. It is shown that the special convenience of this analytical approach lies in the fact that it enables to find out the situations where it is possible to decouple the optical constants and the thickness (to provide correlation-free measurements) of an anisotropic ultrathin film. The accuracy of the obtained formulas for determining the parameters of ultrathin films is estimated by computer simulation of the reflection problem on the basis of the exact electromagnetic theory for anisotropic layered systems.     

Determination of the lattice parameters near the first-order phase transition in the Pb<Subscript>3</Subscript>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript> ferroelastic

A new method for determining the lattice parameters near the first-order phase transition is proposed. The method is based on the model of a thin phase boundary and a linear dependence between the lattice parameters within a phase.     

Time lag parametric identification of a hydrogen permeability model

An inverse problem with dynamic boundary conditions for determining the parameters of a hydrogen permeability nonlinear model is considered. Algorithms are proposed for estimating transport parameters of adsorption, desorption, dissolution, and diffusion depending on the body of experimental information.     

Accuracy of Determining Reverberation Parameters during Recovery of a Signal with Reverberation Distortions in the Case of Discrete Delays

We discuss the accuracy of determining reverberation parameters, which is required to recover a signal with reverberation distortions. It is shown that if the signal with distortions is digitized under conditions of the sampling theorem, then it is insufficient to determine the delay time of the retarded signal with an accuracy of the sampling interval. We present an iterative algorithm for determining the reverberation parameters with sufficient accuracy.     

Interplay among the azimuthally dependent HBT radii and the elliptic flow

We present a calculation of the elliptic flow and azimuthal dependence of the correlation radii in the ellipsoidally symmetric generalization of the Buda-Lund model. The elliptic flow is shown to depend only on the flow anisotropy while in case of correlation radii both flow and space anisotropy play an important role in determining their azimuthal oscillation. We also outline a simple procedure for determining the parameters of the model from data.     

Determination of model parameters for the hydrogen permeability of metals

The nonlinear inverse problem of determining the permeability parameters of metals for hydrogen from experimental data is examined. The model includes adsorption-desorption processes as well as diffusion. An algorithm is proposed for determining the model parameters from a known desorption flux without the need for writing specialized computer programs. Zh. Tekh. Fiz. 68, 38–42 (November 1998)     

Experimental determination of two-point Stokes parameters for a partially coherent broadband light beam

The generalized Stokes parameters, which are two-point extensions of conventional Stokes parameters, are determined for a pair of points in the cross-section of a partially coherent broadband light beam. For this purpose, using a two-mirror and two-beam-splitter assembly, unpolarized, linearly polarized and partially polarized electromagnetic beams are generated. This simple experimental method for determining generalized Stokes parameters establishes an analogy with the experimental scheme of determining conventional Stokes parameters, which in succession contributes to appreciable reduction in uncertainty in the measurements.     

Determination of time-varying contact length,friction force,torque and forces at the bearings in a helical gear system

This paper deals with determining various time-varying parameters that are instrumental in introducing noise and vibration in a helical gear system. The most important parameter is the contact line variation, which subsequently induces friction force variation, frictional torque variation and variation in the forces at the bearings. The contact line variation will also give rise to gear mesh stiffness and damping variations. All these parameters are simulated for a defect-free and two defective cases of a helical gear system. The defective cases include one tooth missing and two teeth missing in the helical gear. The algorithm formulated in this paper is found to be simple and effective in determining the time-varying parameters.     

基于锥形单玻璃管X射线聚焦镜表征X射线光源参数

X射线光源的焦斑尺寸和焦深对X射线光谱学,尤其是对于微区X射线衍射与荧光分析等领域十分重要的参数。如何高效而准确的表征这些参数对于X射线光源的应用和发展至关重要。现有的光源参数表征方法,尤其在表征微焦斑光源的参数时,都存在自身的局限性。锥形单玻璃管X射线聚焦镜是一种常用的X射线聚焦器件。根据锥形单玻璃管X射线聚焦镜滤波特性和几何特点,分析得到聚焦镜的聚焦光能量上限的大小受到光源焦斑尺寸的影响,提出这个能量上限与光源尺寸和光源到聚焦镜入口的距离之间的数学关系。设计了一种基于锥形单玻璃管X射线聚焦镜的表征X射线光源参数的方法。对锥形单玻璃管X射线聚焦镜的参数进行测量和确定后,将聚焦镜放置要测量的光源前,与光源形成聚焦光路。在光路准直并确保只有在聚焦镜内发生单次全反射的X射线射出聚焦镜的情况下,通过改变聚焦镜与光源焦斑距离并利用能谱探测系统来探测聚焦光并得到多个对应的聚焦光能谱。对所得能谱进行计算与分析,得到各能谱中的能量最大值,即聚焦光的能量上限。利用聚焦光能量上限、光源焦斑尺寸和光源到聚焦镜的距离之间的关系并结合线性拟合法,可同时得到光源焦斑尺寸和焦深。选用制造商给出焦斑尺寸约60 μm,焦深为20 mm的微焦斑钼靶光源作为测量对象,利用基于锥形单玻璃管X射线聚焦镜的表征方法测量的结果为焦斑尺寸为60.1 μm,焦深为19.7 mm。用小孔成像法表征该光源焦斑尺寸为60.3 μm,焦深为20.1 mm。相较于现有的方法,基于锥形单玻璃管X射线聚焦镜的表征X射线光源参数方法对表征微焦斑光源有一定优势,对表征高能X射线光源有潜在发展和利用价值。     

Methods for reconstructing equilibrium plasma configurations in the Globus-M spherical tokamak

A magnetic diagnostics allowing one to reliably reconstruct equilibrium plasma configurations in a tokamak over a wide range of operating parameters is developed. The accuracy of determining the geometrical parameters and thermal energy of the tokamak plasma is analyzed in detail. The experimental data obtained in the Globus-M tokamak are processed the with help of the EFIT code. The influence of the plasma configuration on the intensity of the main impurity lines is investigated.     

Thermal Modelling and Characterisation of Semiconductor Bolometers

A revised version of the Griffin & Holland ideal semiconductor bolometer model is presented and its use in determining bolometer properties and parameters from experimental load curve measurements is discussed. We show that degeneracy between some bolometer parameters can only be broken by model fitting a family of load curves over a range of bath temperatures, and that measurements with the bolometer blanked (zero absorbed radiant power) are essential for unambiguous determination of the main parameters. The influence of measurement errors on parameter recovery is analysed using synthetic noisy data sets.     

Possibility of Fast Determination of Radio-Interferometer Parameters

We propose a method for fast determination and systematic monitoring of certain radio-interferometer parameters (the baseline projection and the mounting-site longitude). The method is based on reception of the emission from point radio sources at certain values of their hour angles with the subsequent processing of measurement results using a developed algorithm. We show that the method is applicable for determining the parameters of radio interferometers with both two- and one-channel receivers.     

Optimization and control of parameters of the optical scheme of a heterodyne differential microscope

Dependences of the complex response of a heterodyne differential microscope to test objects on the parameters of its optical scheme are studied. Based on the obtained regularities, methods for controlling and optimizing these parameters are proposed. A procedure for accurately bringing the signal photodetector into coincidence with the center of the Fourier plane of the microscope is described. A method that enables one to control the focusing of the probe beams on an object under study, as well as their nonidentity, is proposed. Conditions for optimizing the size of the signal photodetector are formulated. A correlation between a detuning of the main parameters of the microscope optical system and the error in determining the parameters of an object under study is established.     

Intermittency Phenomena and Super-soft Processes

Starting from the experimental data on the dependence of intermittency phenomena on various physical parameters,it is shown that the average transverse momentum per event plays a decisive role in determining the intermittency strength.This means that intermittency phenomena is closely related to the super-soft processes,observed experimentally in recent years.     

Determining the structural parameters of a low-barrier diode with near-surface δ-doping from data on the temperature dependences of the current-voltage characteristics

A technique for determining the structural parameters of low-barrier metal-semiconductor junctions, the tunnel-transparent barrier of which is formed by high-precision near-surface ??-doping, is described. The following nanostructure parameters have been calculated: the ??-layer depth and the surface concentration of the doping impurity in this layer. Analysis is based on the previously proposed model of thermally assisted electron tunneling in the aforementioned junctions and current-voltage characteristics measured in a specific temperature range.     

Nonaccelerator neutrino physics

The subject of these lectures is experimental nonaccelerator neutrino physics. We discuss experiments on solar and atmospheric neutrino flux measurements, as well as experiments devoted to recording the antineutrino on nuclear reactors in the context of determining the parameters of neutrino oscillations. Neutrino geophysics, a new field of science, is overviewed.     

Technique for determining the cell parameters of the confined one-dimensional photonic crystal,based on the Floquet-Bloch formalism

The technique for determining the cell structural parameters of the confined one-dimensional photonic crystal, based on the strict analytical representation of Floquet-Bloch waves in the form of inhomogeneous waves is proposed.