Table of contents

It is shown that the classical problem of motion of an arbitrary number of particles along a straight line with binary itneraction (shx)⁻² placed under the action of the Morse potential can be solved by using the Lax representation. Exact solution of the equations of motion is reduced to calculation of the matrix exponentials. Existence conditions are determined for the points of equilibrium. The coordinates of particles at those points are defined by zeros of the generalized Laguerre polynomials, which allows us to find explicit expressions for the equilibrium-state energy and frequencies of small oscillations around equilibrium. Comparison is made with the results obtained earlier for the discrete spectrum of the corresponding quantum systems.

The equivalence of the one-dimensional two-fermion model, on one hand, with the two-dimensional Coulomb gas and sine-Gordon models on the other is worked out by employing the Jordan boson representation and the point-splitting regularization. The distinction is made throughout between the bandwidth cut-off and momentum-transfer cut-off. It is shown that the coupling constants, both in the weak-coupling regime and near the Luther-Emery exact solution, scale with the momentum-transfer cut-off. The relationship between the bosonized form of the two-fermion model and the corresponding Fermi gas model is briefly discussed.

Experimental results on the multiplicity distributions and correlations between various types of secondary particles are presented for 800 GeV proton-emulsion nucleus interactions. The results indicate strong correlation between the shower and the grey particles and an independence of the normalised multiplicity with respect to the target mass. The number of grey particles in an interaction is found to be the best experimental measure of the number of intranuclear collisions.

Low- and medium-spin states in ¹⁹⁸Pb are studied using the reaction ¹⁹⁸(³He, 3n) at laboratory energy 27.5 MeV. The in-beam measurements comprise γ-ray singles, γ-RF timing, γ-ray angular distributions and γ-γ coincidences. Seven new levels are located and assigned spins and parities. The previously reported lifetimes are unambiguously assigned: T_1/2(5⁻) = 50.4 ± 0.5 ns, T_1/2(7⁻) = 4.19 ± 0.10 μs and T_1/2(9⁻) = 240 ± 15 ns. The corresponding transition rates B(λ) are deduced. The new non-yrast levels are compared to the existing systematics. A tentative excited (collective) band structure is proposed and compared to a similar one in ¹⁹⁶Pb. Systematic trends in E1, E2 and E3 transition rates in light Pb isotopes are discussed.

We present calculations of energy levels and transition probabilities in 3d and 3d⁹ configurations along the potassium and cobalt sequences for the ions Ti IV to Ag XXIX and Cu III to Dy XL, respectively. Similarly to previous investigations in 3pⁿ and 4pⁿ configurations, approximate relativistic Hartree-Fock wavefunctions were obtained from Cowan's code. The average energy and spin-orbit parameters for the 3d (3d⁹) configurations were adjusted so as to reproduce the observed splittings of the ²D terms or were deduced from the trends of these parameters along the sequences when experimental energy level values are missing.

Proton excitation cross sections and rate coefficients for the 2s² 2p⁵²P_3/2 -2s² 2p⁵²P_1/2 transition in fluorine-like Mg IV, S VIII, Cl IX, Ti XIV and Ni XX have been calculated using the close-coupled impact parameter method. These data are found to be significantly different from earlier results, and will hence lead to changes in the theoretical electron density diagnostic emission line ratios R₁ = I(2s² 2p⁵²P_3/2 -2s² 2p⁵²P_1/2)/I(2s² 2p⁵²P_3/2 -2s2p⁶²S_1/2) and R₂ = I(2s²2p⁵²P_3/2-2s²2p⁵²P_1/2)/I(2s²2p⁵²P_1/2-2s2p⁶²S_1/2) in F-like ions.

Analyses of the XUV spectra of laser produced plasmas of ruthenium and rhodium have yielded the energies of all the levels of the 4s²4p³ and 4s²4p²5s configurations of Ru XII and Rh XIII. The classifications were made possible by isolectronic extrapolations and Hartree-Fock and Dirac-Fock calculations.

Assignments are suggested for 32 transitions in Ar VI involving doublet levels in the 3p³ and 3s3p3d configurations. Beam-foil decay curves are used to measure the lifetimes of these levels, the results being systematically about 25% longer than the values calculated by Fawcett. These decays are also used in ANDC analyses of the lifetimes of the 3s3p²²S, ²P, ²D and 3s²3d²D levels, where the agreement with Fawcett's calculation is generally good. A discussion is also given of the alternative analysis of the Ar VI spectrum recently published by Lesteven-Vaïsse et al. using recoil-ion techniques.

The motion of a liquid in a rectangular tank is considered. A systematic and exact solution is obtained for the time dependent velocity potential of the flow and for the shape of the free surface of the liquid. The problem is treated by using the linearized equations of motion of an inviscid fluid. The flow is assumed to be two-dimensional. The final results are obtained in a form of generalized Fourier series. Some particular cases are examined and several conclusions are drawn.

The fluctuation spectra of the magnetized plasma in the presence of parametric interaction of lower-hybrid waves with modified convective cell modes are analytically derived.

The first part of this paper is devoted to a general survey of Screened Hydrogenic Models (SHM) for atomic structure calculations. New interest is taken in these models because they allow a very fast computation of total energy, one-electron energies, ionization potentials... for any ionic configuration, that can be done on-line in Plasma Physics studies. The a-priori formulation of the SHM is revisited. Then, the additional approximations required to recover a more intuitive formulation based on the notions of inner and outer screenings, and ignoring angular-momentum splitting of the levels, are described. The usefulness of fitting screening constants is discussed. The last part proposes a simple extension of the latter model including l-splitting in a self-consistent manner. Numerical results are presented and discussed.

The results of the rapid quenching from the melt of the pure metals (In, Pb) at high pressures 0.7-8.0 GPa with a cooling rate ~ 10³ K s⁻¹ are presented. The supercooling of the melt was measured, and the high pressure influence on the basic parameters of the solidification process are analysed. The short-range order (SRO) structure of the amorphous alloy Cu_0.85 Sn_0.15 was investigated, and the radial distribution function (RDF) was calculated.

It was shown that at certain (P-T) conditions some tetrahedrally bonded semiconductors can be produced in the amorphous (GaSb) or partially amorphous (ZnSe) state. For amorphous gallium antimonide (a-GaSb) Raman spectra, temperature, heat of crystallization and SRO structure were investigated.

From the theoretical and experimental data one can conclude that a rapid quenching from the melt under high pressure results in a drastic disordering of the structure of the materials or even an amorphization.

Phase relations of ReO₃ have been investigated under high pressure by several methods: by X-ray diffraction in diamond anvil cell up to 30 GPa at 25°C and in boron pellet up to 10 GPa within the range 200-400°C, by DTA method and by quenching up to 9 GPa in the interval 200-1000°C. The regions of existence of cubic ReO₃ and of the two new modifications – hexagonal ReO₃ (superstructure type as Fe₃N) and rhombohedral ReO₃ (VF₃ structure type) have been determined under high pressure. The cubic ReO₃ undergoes the disproportion within the range 2-5 GPa at 340-380°C. The rhombohedral ReO₃ and cubic ReO₃ transform to hexagonal ReO₃ when heating above 340-250°C in the pressure range 5-9 GPa. Hexagonal ReO₃ is metastable under normal conditions.

We report on a first-principle theoretical study of the structural properties of the α and β phases of the ternary semiconductor CdIn₂ Se₄. We have also studied the properties of two intermediate phases in a possible transition process α → β. Besides a good agreement with the experiment our overall result is that all these phases have so similar structural properties that in most of the cases the consideration of the simplest phase from the crystallographic point of view should be quite enough, with substantial savings in computer time. This result should also hold for the other members of the AB₂C₄ semiconductor family with D_2d¹ space group symmetry and should allow for an easier systematic investigation of their physical properties.

We have developed a general X-ray diffraction model which enables to investigate interfacial disorder in crystalline/amorphous and crystalline/crystalline multilayers. Using classical structure factor calculations, we simulate the evolution of the diffracted X-ray intensities as a function of the fluctuation amplitude, the superlattice wavelength and the interatomic distances. From experimental X-ray diffraction patterns, the interfacial disorder is extracted as a function of superlattice wavelength for various crystalline/crystalline systems. An enhanced lattice mismatch between the two components gives rise to an increase of interfacial disorder.

Magnetic instability during asymmetric magnetization reversal in crystalline materials was first investigated systematically by Néel who interpreted it as a superposition of the reptation (=accomodation) and bascule effects. We found similar effects in the amorphous Fe-B alloy but the changes of magnetic polarization were smaller than in the crystallized state, and there was a bigger stability region inside the hysteresis loop. The dependence on the number of magnetization reversals in the amorphous and appropriate crystalline materials is also different.

The magnetic field and loss in an apparatus for the determination of magnetic properties of electrical steel under rotational flux conditions using field sensing coils (H-coils) is numerically analyzed by means of finite-element calculations in order to improve the accuracy of the apparatus. The method considered here is based on the determination of the field quantities and makes use of square-shaped samples and an air gap between the pole faces and the sample. The influence of various parameters is studied. The errors in field strength and loss decrease with decreasing gap, but for small gaps it is difficult to obtain circular rotational flux under sinusoidal primary voltage conditions. Furthermore, two different concepts of the determination of rotational loss are considered.

We report our studies on fabrication and superconducting properties of YBa₂ Cu₃ O_7-y thin films prepared by d.c. magnetron sputtering from a single "1-2-3" target and subsequent heat treatment. The films exhibited sharp resistive transitions and zero-resistance temperatures above 85 K. XPS results indicate that the stoichiometry of our films was close to the target composition.

Measurements of the elastic peak intensity make possible estimation of the true inelastic mean free path (IMFP). Corresponding experiments are relatively simple and can be performed for any sample. The theoretical models can be used to derive the relation between elastic peak intensity and IMFP for single and multiple elastic scattering. In the present work both models were based on the differential scattering cross-sections calculated within the partial wave expansion method. Examples of calculations of the IMFP using both theoretical models are presented.

Many properties of high-temperature superconductors clearly indicate that a mechanism different than the BCS one is responsible for their superconductivity. It seems that bipolaronic models can give sufficient explanation of essential problems in terms of Bose-Einstein condensation of hole pairs in real space. The only difficulty of a too large effective mass of the conventional bipolaron may be avoided by considering Chakraverty's peroxitons (O⁻-Cu⁺ -O⁻) which are true bosons with relatively low mass. According to the structure of YBa₂ Cu₃ O_7-y we propose to treat it as a two-component boson system which consists of a quasi-one-dimensional boson gas for the Cu1-O1 chains and a quasi-two-dimensional boson gas for the Cu2-O2-O3 layers. As a first approximation we treat both subsystems as ideal boson gases. The oxygen content influences strongly the number of peroxitons in chains and layers as well as their effective masses and, therefore, critical temperature of the system. Within the proposed approach we expect different superconducting phases and critical temperatures depending on oxygen content.

In this paper we present analytical expressions for the Hall coefficient and the electronic contribution to the thermoelectric power as a function of energy for a metal with a Fermi surface which is distorted by a pair of Bragg planes. Our results obtained by using an isotropic relaxation time are compared with the experimental data.

The paper aims at determining curves of magnetizing using a new method of measuring, as demonstrated on (Ni-Zn) ferrites of the type Permax.

For various temperatures of sintering of ferrites, the anisotropy of the induction of investigated material, caused by the introduction of axial thrust during the formation of samples was determined. The thrust is of considerable practical importance and makes it possible to produce materials possessing higher values of magnetic permeability. By applying the magnetic circuit described in the paper, there appears a possibility of determining the directional changes of other material constants (magnetostriction, core loss, apparent core loss, etc.).

An angle-resolved photoemission study of a ZrN_0.93 (110) single crystal is reported. Off-normal spectra recorded using unpolarized Ne I and He I resonance radiation are presented and the determined experimental peak dispersion are compraed with possible direct transitions calculated for ZrN_1.0. The results show that dominant emission peaks at these photon energies probably are one-dimensional density of states features, i.e., peaks originating from band extrema. A peak observed at about 2eV below the Fermi energy is interpreted as originating from occupied vacancy states.

A study is made of the stress annealing on the magnetic properties of Fe-Si samples as a function of carbon and silicon content and prolonged lowtemperature annealing prior to stress annealing. The data obtained are compared with those of magnetic annealing investigations.

The magnetic or stress annealing or stress-field annealing effects on domain structure and magnetic properties are compared on one and the same sample. The thermal stability of losses after stress or magnetic annealing is investigated.

The results permit the conclusion that the origin of the induced magnetic anisotropy under stress annealing in the elastic region is the same as that in the case of magnetic annealing.

Edge burrs are known to cause increases in losses of large power transformers but it is difficult to quantify their effect. A single phase experimental transformer core was prepared with arrays of thermistors to measure the localised loss when artificial burrs were introduced in a controlled manner. When laminations were completely shorted in the core the total core loss rose by almost 100% and localised losses rose to over 50 W kg⁻¹. Partial burrs as occur in practice caused smaller but nevertheless significant increases in loss also. The high localised losses occurred in regions in which the eddy currents caused by the burrs was computed to be high.

The electronic structure of light rare earth impurities (Pr, Nd and Pm) in 5d-metals (Ir and Ta) is studied theoretically by means of a supercell approximation. For Pr in Ir a non-magnetic state is calculated to be stable, while the other impurity-host combinations give spin-polarized states. For Pm in Ir and Ta an almost complete spin-polarization is obtained. The results are compared with experiment and a qualitative agreement is found.

In external fields parallel to the rolling direction (r.d.) a g.o. SiFe sheet shows besides a stray-field structure due to grain boundaries the field-dependent edge peaks at the bounds of the specimen with strong components normal to the sheet plane. The present investigations concern the static stray-field behaviour of a g.o. 3% SiFe sheet (5mm × 20mm × 300μm) stacked upon a joint of two little sheets (5mm × 5mm × 300μm each) with a gap as small as possible between them. In low external fields parallel to r.d. nearly no interaction between the laminations was observed. Increasing the external field up to a critical value led to a remarkable change in the behaviour of the upper single strip due to a stray-field interaction.

The kinetics of formation the f.c.c. γ phase at 1180°C have been studied metallographically in Fe-28.02Cr-24.67Co-1.04Si (wt.%) alloy. Selected (α + γ) phase specimens subjected to electron microprobe analysis showed a depletion of the γ phase in Co, usually accompanied by an enrichment in Cr.

Deterioration of permanent magnet properties (but not the saturation magnetization) as the α → γ transformation proceeds is described.

Grain-oriented silicon steels of various thickness were built into 3-phase stacked cores, and the relationship between the building factor (B.F.) and the material loss was discussed. The loss component proportional to square of frequency (W_e), and the ratio of W_e to total loss too, decrease as the thickness of the silicon steel decreases, while the loss component proportional to frequency (W_h) is nearly constant for the high grade silicon steels of various thickness. In the case that silicon steels have same thickness, the B.F. deteriorates with decreasing material loss. But in the case that the thickness varies for high grade steels the B.F. does not change in spite of varying material loss. Using thin silicon steels, the core loss of transformers can be decreased in the same ratio of the material losses.

Because of its high diffusivity in silicon, aluminium is best suited for the deep diffusions often required in high voltage power semiconductor devices. The ion implantation technique allows the reproducible low dosage doping necessary, e.g., for the new concepts of junction termination systems.

The most important draw back of the use of aluminium as a p-type dopant in silicon is its low electrical activity after the anneal. The main problem therefore is the enhancement of the aluminium yield (the amount of electrically active Al with respect to the implanted dose). Sheet resistivity and spreading resistance measurements after various annealing processes are presented as well as a triple implant process, which allows to enhance the aluminium yield.

New metallographic cooling rates have been calculated for the iron meteorites Carlton (IIICD), Toluca (IAB), and Odessa (IAB) based on the central Ni concentration versus taenite width method. New kamacite bandwidth cooling rates have been calculated for the members of group IVB, the ungrouped iron meteorite Chinga, and the high-Ni members of IIICD and IAB. The cooling rates determined are up to several orders of magnitude faster than those previously reported.

A difference of about a factor of 60 is found between the kamacite bandwidth cooling rate and the central Ni versus taenite width cooling rate of the same meteorite, Carlton. This discrepancy is interpreted as resulting from extensive regolith accretion on the parent body at the time of Widmanstätten pattern formation.

No systematic trend is found in the cooling rates as a function of bulk meteorite Ni of the magmatic group IVB. Combined with the strong inter-element correlations found in group IVB [15], the constant cooling rate suggests a core origin of this group.

No systematic cooling rate variation is found in neither of the non-magmatic groups IIICD or IAB. Combined with the weak or missing inter-element correlations in these groups, the results of the present work support the megaregolith melt pool scenario suggested by Wasson et al. [1] for the origin of the non-magmatic groups IIICD and IAB.