Lifetimes of anion vacancies and <Emphasis Type="Italic">F</Emphasis><Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> color centers in lithium fluoride following irradiation

A method is developed for determining the mean lifetime of anion vacancies in dielectric crystals following irradiation. This method is used to study the temporal kinetics of the concentrations of vacancies and F ₂⁺ color centers in lithium fluoride crystals irradiated by ionizing radiation. It is then possible to study the dependences of the vacancy lifetime on the concentration of F ₁ color centers, temperature, and impurity content of a crystal. Vacancy and F ₂⁺ color lifetimes determined by this method are given.     

On the determination of the potential functions of H<Subscript>2</Subscript>Co,PH<Subscript>3</Subscript>, and CH<Subscript>4</Subscript> molecules based on experimental data

In the present work, a method of determining multidimensional potential surfaces of polyatomic molecules is suggested. The method is based on the use of high-accuracy data on the vibrational-rotational band centers and results of vibrational-rotational theory. Results of application of the method to the CH ₄, PH₃, AsH₃, and H ₂CO molecules are presented. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 58–63, February, 2008.     

Thermal expansion and thermal conductivity of single-crystal Cu<Subscript>x</Subscript>Ag<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>InS<Subscript>2</Subscript> solid solutions grown by the moving solvent method

Single crystals of Cu_xAg_1−x InS₂ solid solutions are grown by the moving solvent method. The compositions and structures of the single crystals are determined. The thermal expansion coefficients of these crystals are determined with a dilatometer. The thermal expansion coefficients are found to vary linearly with concentration x. The thermal conductivity of the crystals is measured by the absolute method, and the concentration dependence of the thermal conductivity is constructed. This dependence is shown to have a minimum near the equimolar composition.     

<Superscript>6</Superscript>He + <Superscript>6</Superscript>He Clustering of <Superscript>12</Superscript>Be in a Microscopic Algebraic Approach

The norm kernel of the A=12 system composed of two ⁶He clusters, and the L=0 basis functions (in the SU(3) and angular momentum-coupled schemes) are analytically obtained in the Fock-Bargmann space. The norm kernel has a diagonal form in the former basis, but the asymptotic conditions are naturally defined in the latter one. The system is a good illustration for the method of projection of the norm kernel to the basis functions in the presence of SU(3) degeneracy that was proposed by the authors. The coupled-channel problem is considered in the algebraic version of the resonating-group method, with the multiple decay thresholds being properly accounted for. The structure of the ground state of ¹²Be obtained in the approximation of zero-range nuclear force is compared with the shell-model predictions. In the continuum part of the spectrum, the S-matrix is constructed, the asymptotic normalization coefficients are deduced and their energy dependence is analyzed.     

Electron/pion identification in the CBM TRD applying a ω<Stack><Subscript><Emphasis Type="Italic">n</Emphasis></Subscript><Superscript><Emphasis Type="Italic">k</Emphasis></Superscript></Stack> goodness-of-fit criterion

The problem of electron/pion identification in the CBM experiment based on the measurements of energy losses and transition radiation in the TRD detector is discussed. Earlier we analyzed a possibility to solve such a problem using an artificial neural network (ANN) [1]. Here we consider an approach based on a nonparametric ω _n ^k goodness-of-fit criterion, and comparison with the ANN method is also performed. We show that both methods provide a comparable level of pion suppression and electron identification, the ω _n ^k test is more simple for practical applications, the ANN method provides the needed level of pions suppression only if “clever” variables are used. We demonstrate that application of the ω _n ^k -criterion to the J/Ψ reconstruction provides a high level of pion background suppression and significantly improves a signal-to-background ratio. The text was submitted by the authors in English.     

Design of Plane-Symmetric Low <Emphasis Type="Italic">F</Emphasis>-number Reflective System Based on Perturbation Aberration Model

All-reflective optical systems have theoretically no chromatic aberration and are suitable for wide spectral application, but co-axial reflective systems are difficult to design as low F-number optical systems. In this paper, the aberration of plane-symmetric optical systems with low F-number is analyzed based on the wavefront derived from optical path length. Up to third-order aberrations are classified into three categories by their characteristics. The reduction method of the dominant aberration, astigmatism-like aberration, is proposed. In the method, the Gauss image plane is modeled by means of a simplified mirror surface with third-order approximation. Because the system is plane-symmetric, symmetric cross section and asymmetric cross section are modelled differently. The design example of a three-mirror system with F/2 is shown.     

Transition prediction of a hypersonic boundary layer over a cone at small angle of attack—with the improvement of e<Superscript><Emphasis Type="Italic">N</Emphasis></Superscript> method

The problem of transition prediction for hypersonic boundary layers over a sharp cone has been studied in this work. The Mach number of the oncoming flow is 6, the cone half-angle is 5°, and the angle of attack is 1°. The conventional e ^N method is used, but the transition location so obtained is obviously incorrect. The reason is that in the conventional method, only the amplifying waves are taken into account, while in fact, for different meridians the decay processes of the disturbances before they begin to grow are different. Based on our own previous work, new interpretation and essential improvement for the e ^N method are proposed. Not only the amplification process but also the decay process is considered. The location, where by linear stability theory, the amplitude of disturbance wave is amplified from its initial small value to 1%, is considered to be the transition location. The new result for transition prediction thus obtained is found to be fairly satisfactory. It is also indicated that for the calculation of base flow, boundary layer equations can be used for a small angle of attack. Its computational cost is much smaller than those for DNS. Supported by the National Natural Science Foundation of China (Grant Nos. 10632050 and 90716007), the Special Foundation for the Authors of National Excellent Doctoral Dissertations (Grant No. 200328), and the Foundation of Liu-Hui Center of Applied Mathematics of Nankai University and Tianjin University     

Data analysis method to achieve sub‐10 pm spatial resolution using extended X‐ray absorption fine‐structure spectroscopy

Obtaining sub‐10 pm spatial resolution by extended X‐ray absorption fine structure (EXAFS) spectroscopy is required in many important fields of research, such as lattice distortion studies in colossal magnetic resistance materials, high‐temperature superconductivity materials etc. However, based on the existing EXAFS data analysis methods, EXAFS has a spatial resolution limit of π/2Δk which is larger than 0.1 Å. In this paper a new data analysis method which can easily achieve sub‐10 pm resolution is introduced. Theoretically, the resolution limit of the method is three times better than that normally available. The method is examined by numerical simulation and experimental data. As a demonstration, the LaFe_1–xCr_xO₃ system (x = 0, 1/3, 2/3) is studied and the structural information of FeO₆ octahedral distortion as a function of Cr doping is resolved directly from EXAFS, where a resolution better than 0.074 Å is achieved.     

<Emphasis Type="Italic">F</Emphasis><Subscript>2</Subscript> challenging DGLAP

The low-x data of the structure function F ₂ measured by the collaborations H1 and ZEUS are compared with the prediction of the DGLAP equations. A new method of comparing data and theory is presented. The systematic and quantitative analysis shows that the predicted 1/x behavior deviates increasingly from the observed one as x decreases below 10^-3.Received: 31 October 2003, Published online: 26 May 2004     

Extension of the Random-Phase Approximation for <Emphasis Type="Italic">γ</Emphasis>-soft nuclei

The variational method is formulated which extends the Random-Phase Approximation to γ-soft nuclei.     

Comment: “On the computation of molecular auxiliary functions<Emphasis Type="Italic">A</Emphasis><Subscript>n</Subscript>and<Emphasis Type="Italic">B</Emphasis><Subscript>n</Subscript>”

Guseinov, Mamedov, Kara and Orbay (Pramana - J. Phys. 56, 691 (2001)) propose methods for evaluating the molecular auxiliary functionsA _n(p) andB _n(pt) for the range 17 ≤n ≤ 60 and 25 ≤pt ≤ 60. However, their procedure forA _n(p) is not new, and that forB _n(pt) is less efficient for their target range than another well-known method. Their approach does have merit for smaller non-zero values ofpt. Two minor errors in table 1 of their paper are also identified.     

Temperature determination of (CF<Subscript>3</Subscript>I)<Subscript><Emphasis Type="Italic">N</Emphasis></Subscript> clusters in a beam by time-of-flight measurements of IR-laser excited SF<Subscript>6</Subscript> molecules sublimating from the surface of clusters

The method is described and the experimental results are presented on the temperature determination of the (CF₃I) _N clusters in a beam (N ⩽ 10² is a number of monomers in a cluster) using SF₆ molecules from intersecting molecular beam as probe thermometers. The SF₆ molecules are captured by clusters in the crossed cluster and molecular beams and, after a certain time, sublimate from the surface of clusters carrying information on the velocity and temperature (internal energy) of clusters. Using time-of-flight (TOF) method the kinetic energy (velocity) of sublimated SF₆ molecules was measured and the temperature of clusters was determined to be T _cl = (88 ± 15) K.     

Response to the Comment: “On the computation of molecular auxiliary functions<Emphasis Type="Italic">A</Emphasis><Subscript>n</Subscript>and B<Subscript>n</Subscript>”

The Comment ‘on the computation of auxiliary functionsA _n(p) and B_n(pt)’ (FEHarris, Pramana - J. Phys. 61, C779 (2003)) is analysed in the arbitrary range of parametersn,p andpt. It is shown that our downward recursion approach forB _n(pt) in the range (n/pt) > 1 is more efficient than the well-known upward recursion method, and the upward recursion procedure forA _n(p) does not have merit for smaller non-zero values ofp (p < 001).     

Dynamics of the Weyl scale invariant non-BPS <Emphasis Type="Italic">p</Emphasis> = 3 brane

In this paper a Weyl scale-invariant p = 3-brane scenario is introduced, with the brane embedded in a higher-dimensional bulk space with N = 1, 5D Super-Weyl symmetry. Its action, which describes its long wave oscillation modes into the ambient superspace and breaks the target symmetry down to the lower dimensional Weyl W(1, 3) symmetry, is constructed by the approach of coset method.     

New spherically symmetric solutions in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>)-gravity by Noether symmetries

Spherical symmetry for f (R)-gravity is discussed by searching for Noether symmetries. The method consists in selecting conserved quantities in form of currents that reduce dynamics of f (R)-models compatible with symmetries. In this way we get a general method to obtain constants of motion without setting a priori the form of f (R). In this sense, the Noether symmetry results a physical criterium. Relevant cases are discussed.     

Enhancement of the defect field of one-dimensional photonic crystals containing <Emphasis Type="Italic">ε</Emphasis>-and <Emphasis Type="Italic">μ</Emphasis>-negative layers

Employing the transfer matrix method, we study the electromagnetic field of one-dimensional photonic crystals with a defect inserted by pairs of μ-negative (MNG) and ε-negative (ENG) material layers. The fields within the pairs of layers and the matrix defect are independent of each other, and the whole field is their superposition. The whole defect field can be significantly enhanced by pairs of ε-negative and μ-negative layers. In contrast to the conventional defect modes, the intensity and volume of the defect field with pairs of ε-negative and μ-negative layers can be precisely adjusted.     

Magnetic behaviour of doped dimer compounds Sr<Subscript>3</Subscript>Cr<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>M<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>8</Subscript> (M = V,Mn)

Wilson chains, based on a logarithmic discretization of a continuous spectrum, are widely used to model an electronic (or bosonic) bath for Kondo spins and other quantum impurities within the numerical renormalization group method and other numerical approaches. In this short note we point out that Wilson chains can not serve as thermal reservoirs as their temperature changes by a number of order ΔE when a finite amount of energy ΔE is added. This proves that for a large class of non-equilibrium problems they cannot be used to predict the long-time behavior.     

Relaxation kinetics of photoconductivity in <Emphasis Type="Italic">р</Emphasis>-silicon compensated by phosphorus atoms

The relaxation kinetics of photoconductivity in neutron-doped silicon (NDS) of the p-type is discussed. It is found that the relaxation process in the compensated p-Si<B, P> differs from that in the reference p-Si<B> sample. The difference is explained on the basis of concept of different micrononuniformity of the material conductivity. A method based on studying the dependences of charge-carrier mobility on annealing time is developed for determining thermal annealing of structural defects.     

Investigation on optical properties of Bi<Subscript>2.85</Subscript>La<Subscript>0.15</Subscript>TiNbO<Subscript>9</Subscript> thin films by prism coupling technique

Layered-perovskite ferroelectric Bi_2.85La_0.15TiNbO₉ (LBTN) optical waveguiding thin films were grown on fused silica substrates by pulsed laser deposition (PLD). X-ray diffraction (XRD) revealed that the film is highly (00l) textured. We observed sharp and distinct transverse electric (TE) and transverse magnetic (TM) multimodes and measured the refractive indices of LBTN thin films at 632.8 nm. The ordinary and extraordinary refractive indices were calculated to be n _TE=2.358 and n _TM=2.464, respectively. The film homogeneity and the film-substrate interface were analyzed using an improved version of the inverse Wentzel–Kramer–Brillouin (iWKB) method. The refractive index of the film remains constant at n ₀ within the waveguiding layer. The average transmittance of the film is 70% in the wavelength range of 400–1400 nm and the optical waveguiding properties were evaluated by the optical prism coupling method. Our results showed that the LBTN films are very good electro-optical active material.