Studies of the EMC effect in the QCD framework with the EMC iron and hydrogen structure functions

The QCD evolution of the measured structure functions F₂ in iron and hydrogen have been analysed to show that the momentum distribution of the valence quarks is lower in iron than in hydrogen and that the opposite is true for the gluon and sea quark distributions in the region of 0.1<x<0.65.     

Measurement of the real part of the K−n forward scattering amplitude between 1.2 and 2.6 GeV/c

The differential cross sections of the combined elastic and break-up K^?d reaction have been measured at 1.21, 1.42 and 2.61 GeV/c incident K^? momentum. The measurements have been performed at the CERN PS using multiwire proportional chambers. The values of the invariant momentum transfer t explored (0.0005<|t|<0.1 GeV²) include the Coulomb-nuclear interference region. The differential cross sections have been analysed in the framework of the Glauber impact-parameter formalism. The observed interference effects have been used to derive the ratio of the real to imaginary part of the forward K^?n nuclear amplitude.     

The melting behaviors of the Nb(1 1 0) nanofilm: a molecular dynamics study

By using molecular dynamics (MD) and the modified analytic embedded atom method (MAEAM), we have studied the melting point, the melting mechanism and the correspondingly dynamical behaviors of a Nb(1 1 0) nanofilm. Firstly, in accordance to the MD time dependence of the potential energy, the melting point of this nanofilm has been roughly estimated. Then, the melting mechanism of the nanofilm have been analyzed in detail with the application of the structure factor. The results clearly indicate that the melting transition of the 8th, 9th, and 10th atomic layer of the nanofilm has been characterized by the exponential, polynomial and linear sequence respectively when the thickness of the quasiliquid film attains to about 1.3 nm. Thirdly, the dynamical behaviors of the nanofilm melting, such as the melting front propagation velocity and the kinetic coefficient, which have also been analyzed, demonstrate that the melting front propagation velocity has linearly increased with the incremental temperature and the evaluated kinetic coefficient has approximately equaled 1.43m/(sK). Finally, by extrapolating the melting front propagation velocity to zero, we can accurately deduce the melting point of the Nb(1 1 0) nanofilm to 2568.3 K, which is much lower than the counterpart (2740 K) of the bulk niobium.     

Effect of interparticle interactions on the dynamical properties of γ-Fe2O3 nanoparticles

The dynamical properties of γ-Fe₂O₃ nanoparticles dispersed in a polymer have been investigated by means of AC susceptibility measurements in a large frequency range (10<ν<10⁴ Hz) and Mössbauer spectroscopy measurements. The frequency dependence of the blocking temperature, T_B, has been analysed for a series of samples with the same volume distribution and interparticle interactions of different strengths. An increase of the effective energy barrier with increasing interaction strength has been observed unambiguously, in agreement with our model, based on a statistical calculation of the interaction energy for a disordered assembly of particles with volume distribution and easy axes in random directions.     

Experimental limits on the strength of weak neutral currents in lepton pair production at PETRA energies

The processes e⁺e^? → e⁺e^? and μ⁺μ^? have been studied at PETRA using the JADE detector. The data, which were collected at s-values of up to 1300 GeV² have been analysed in terms of an electro-weak extension of QED to obtain values for the weak vector and axial vector couplings in the lepton sector. The values obtained agree with the predictions of the standard Salam-Weinberg model and the data are further analysed in terms of this model to obtain the limits 0.10 < sin²?_w < 0.40 (68% CL). The mass of the neutral weak gauge boson is deduced to be greater than 51 GeV/c².     

Single-scale wavelet representation of turbulence dynamics: Formulation and Navier-Stokes regularity

The ‘triad interactions’, arising from the spectral resolution of the nonlinear terms in the Navier-Stokes equations, have so far not been substantially modified in the wavelet representation. In this paper, the multiscale interactions are captured by exact expressions evaluated at a single scale of the Mexican hat wavelet coefficients: the larger-scale terms as a volume integral of nearby wavelet coefficients, and the smaller-scale contributions as iterated Laplacians of the coefficient at the point of interest. As a result, the Navier-Stokes equations are expressed exactly at a single scale. This facilitates the evaluation of the dominant Hölder exponent near singularities. From the scaling properties of wavelet coefficients, it is shown that Euler dynamics would generate stronger singularities for any h<1, but that viscous dynamics would not unless h<−1 (a discontinuous case). We discuss how this conclusion could be affected by boundary conditions.     

Magnetic and electrical properties of bismuth cobaltite Bi24(CoBi)O40 with charge ordering

The compound Bi₂₄(CoBi)O₄₀ has been synthesized using the solid-phase reaction method. The temperature and field dependences of the magnetic moment in the temperature range 4 K < T < 300 K and the temperature dependences of the EPR line width and g-factor at temperatures 80 K < T < 300 K have been investigated. The electrical resistivity and thermoelectric power have been measured in the temperature range 100 K < T < 1000 K. The activation energy has been determined and the crossover of the thermoelectric power from the phonon mechanism to the electron mechanism with variations in the temperature has been observed. The thermal expansion coefficient of the samples has been measured in the temperature range 300 K < T < 1000 K and the qualitative agreement with the temperature behavior of the electrical resistivity has been achieved. The electrical and structural properties of the compound have been explained in the framework of the model of the electronic-structure transition with inclusion of the exchange and Coulomb interactions between electrons and the electron-phonon interaction.     

Investigation of the thermoelastic phase transformation in a NiAl alloy by molecular dynamics simulation

The Ni_xAl_1−x alloys exhibit shape memory effect, for which thermoelastic phase transformations are essential, in the composition range of 60<x<65. The analytical studies are very difficult on the thermoelastic phase transformations because these types of transformations exhibit anharmonic behaviour. In order to overcome this difficulty, it is possible to benefit from the molecular dynamics (MD) calculations based on interatomic interaction potentials. In the present study, the interatomic interactions of Ni_62.5Al_37.5 alloy have been modelled by means of Lennard-Jones potential energy function. A MD cell of 1024 atoms in B2 super lattice has been chosen and the structural changes were investigated on this system with changing temperature. It has been observed that the model alloy exhibits the thermoelastic phase transformation with thermal cycling. A hysteresis has been determined between forward and backward transformation temperatures. The structural analysis is also done before and after the transformation.     

Investigation of states in 30P via the 30Si(3He,t)30P reaction at 30 MeV

The ³⁰Si(³⁰He, t)³⁰P reaction has been measured for about 100 levels in ³⁰P with E_x < 8.8 MeV. Little selectivity in the population of states has been observed. For 75 levels angular distributions have been analysed using a “fingerprint method” by determining the L-value from a comparison in shape with transitions to states with known J^π. For possible mixed L-transitions a dominance of the higher L-value is observed for almost all cases. Coulomb displacement energy calculations utilizing shell-model wave functions have been used to identify T = 1 states.     

The mechanism of surface heterodiffusion at elevated temperatures

Molecular dynamics simulations employing the Lennard-Jones potential have been performed on Kr/Ar(111) to investigate the nature of high-temperature surface heterodiffusion. These suggest that high activation energies and preexponential factors observed experimentally at temperatures above approximately 0.70 T_m arise from adatom-vacancy pair formation, which sharply increases the number of mobile species. Evidence is also obtained that at intermediate temperatures (0.45 T_m < T < 0.66 T_m), Arrhenius curves mass transfer diffusivity can depend on both coverage and adsorbate interactions. For adsorbates which exhibit islanding, low coverage diffusion is characterized by an activation energy equal to the enthalpy of migration, whereas at moderate coverage the activation energy contains an additional term due to the enthalpy of formation of mobile adatoms from immobile islands.     

Interpretation of kinetics of iron surface oxidation involving the real structure of single crystal samples

The kinetics of oxidation of iron surface has been studied by AES method. The effects of oxygen diffusion into the lattice defects have been considered in the discussion of the mechanism of the oxygen adsorption. The real sticking coefficient has been determined as a function of oxygen coverage (S=1?θ in the range of 0<θ<0.9). The oxidation of iron surface occurs in two steps. At the first step the dissociative oxygen adsorption occurs for the coverage 0<θ _O<1 and the rate of the oxygen molecule adsorption is limiting. At the second step, in the range of oxygen coverage 1<θ _O<2, the reconstruction of the iron surface occurs with the formation of free adsorption sites. At this step the sticking coefficient of oxygen is almost constant (S≈0.1).     

Optical-axis perturbation in nonplanar ring resonators

Several findings on the optical-axis perturbation of nonplanar ring resonators have been obtained identical by utilizing the augmented 5 × 5 matrix formulation and augmented 6 × 6 matrix formulation, respectively. It has been found out that in the whole region of 0 < L/R < 2, the longer the mirror radius, the higher the sensitivity of optical-axis decentration, while the total cavity length is L and the radius of the curvature mirrors is R. The sensitivity of optical-axis tilt in the region of 0 < L/R < 2 has been carried out too. The optical-axis decentration and optical-axis tilt inside the region of L/R > 2 have been discussed. The differences of the optical-axis perturbation between planar and nonplanar ring resonators have also been analyzed. These interesting findings are important to the cavity design of nonplanar ring resonators.     

Numerical determination of the capture/escape boundary for the Hénon attractor

The capture escape boundary for the Hénon attractor has been determined by numerical methods. In the region of attraction where -1<b<1, a principal boundary and secondary boundaries corresponding to attracting sets of s components (s=3, 5, 6, 7, 8, 10 and 12) have been detected. Bifurcations between these secondary boundaries have also been obtained.     

Formation of a cluster structure in the PbZr<Subscript>1 – <Emphasis Type="Italic">x</Emphasis> </Subscript>Ti<Subscript> <Emphasis Type="Italic">x</Emphasis> </Subscript>O<Subscript>3</Subscript> system

Microdeformations of the crystal lattices in the phombohedral and tetragonal regions of the PbZr_1–xTi_xO₃ phase diagram have been calculated and their dependences on the titanium concentration have been constructed. Based on an analysis of these dependences, it has been concluded that tetragonal-phase clusters form in the range 0.11< x < 0.12 and rhombohedral-phase clusters form in the range 0.725 < x < 0.750.     

Hamiltonian treatment of self-dual antisymmetric tensors

Self-dual antisymmetric tensors occur in certain (4n + 2)-dimensional supergravity models, in particular the one connected to type IIB superstrings. So far they have been quantized only using light front methods. Here we show that the existing covariant action for such fields leads to a consistent hamiltonian system also for ordinary “timelike” dynamics, although rather complicated second class constraints are present.     

The proton relaxation timesT 1 in binuclear copper complexes

Proton spin-lattice relaxation times as a function of temperature for two kinds of binuclear copper complexes with antiferromagnetic exchange interactionJS₁S₂ have been measured in order to understand the relaxation effects in exchange clusters. It is shown that the results reflect the coupling of the nuclear and electron subsystems; in the rangekT<J the coupling of the subsystems is modulated by temperature independent processes, in the rangekT≥J the temperature dependence of the dynamics of the electron subsystem is manifested. The response of the nuclear subsystem to the change in the nature of magnetic excitations is discovered.     

Reactivity screening of silica

As a screening of the chemical activity of silica [SiO₂/Si(1 0 0)], which is one of the most often used supports for nanostructures, thermal desorption spectroscopy data have been gathered for a variety of gases such as n-nonane, n-hexane, n-butane, iso-butane, ethane, CO₂, CO, O₂, and H/H₂. Whereas, the alkanes with chain lengths larger than three adsorb with large binding energies (E_d = 50-70 kJ/mol), the activity towards the other probe molecules is negligible (<24 kJ/mol) down to adsorption temperatures of 95 K. The adsorption of n- and iso-butane has additionally been studied by molecular beam scattering and follows standard precursor mediated adsorption dynamics.     

Universal conductivity variation in glassy Zr-M alloys

Temperature dependence (3–300 K) of the electrical conductivity in a number of amorphous Zr_1?xM_x alloys (M = Cu, Ni, Co and Fe, 0.19 < x < 0.71) has been analysed in some detail. Like in some other alloys with a high electrical resistivity, the conductivity varies as T at lower temperatures (T < 80 K) and √T at higher temperatures. A new feature observed is that the ratio of the coefficients of a low temperature T and a high temperature √T conductivity variation is practically constant for allalloys. Therefore a universal conductivity-temperature curve can be constructed for all amorphous Zr_1?xM_x alloys with the resistivity higher than 150 μohms cm. These results are consistent with the effects of incipient localisation and indicate that the electron-phonon coupling determines the conductivity variation.     

Photoemission study of Pd Zr and Cu Zr alloys

The XPS valence bands and core levels of the alloys Pd_1?xZr_x (0<x<1) and Cu_1?xZr_x (0<x<1) have been measured. The alloys prepared by coevaporation are crystalline — but their valence band spectra are close to those of the metallic glasses of the same compositions. The large valence band and core level shifts observed for Pd can be explained by a simple theory, not necessitating the postulation of a new type of bonding in these systems.