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Computational and graphical results on Halley's method for one-parameter rational functions of the form ζ^α − 1 = 0 are presented. Level sets for inf {|H_ζ0ⁿ: n = 1, 2, ...} and index (ζ₀) reveal a visually striking and intricate class of patterns indicating behavior ranging from stable points to chaos.

Similarities and differences between the single-particle orbitals of the Nilsson and Woods-Saxon average potentials are investigated in detail for deformed nuclei in the rare-earth and actinide regions. The neutron single-particle orbitals are found to be similar in the two potentials in the rare earth region, while in the actinide region large differences are found. These differences can, however, be significantly reduced by changing the Nilsson model parameters κ and μ. The proton single-particle orbitals show small but systematic differences both in the rare earth and actinide region. The origin of these differences can be traced back to the Coulomb interaction, which is not explicitly considered in the Nilsson potential.

The excitation of a fast ion beam, by a laser beam perpendicular to the ion beam axis at the exit of a carbon foil, has been studied both theoretically and experimentally. The laser was tuned to a transition 1 → 2 of an ion first excited by a carbon foil. The population changes of levels 1 and 2 in the laser field are expressed as a function of the relevant parameters. Beam-foil-laser experiments have been realized using hydrogen beams (~ 100 keV/amu), preexcited in a carbon foil, interacting with a cw dye laser inside its cavity. Experimental results are in good agreement with our calculations.

We consider normalized Slater-type orbitals _nlm^(α)(q) in the momentum space representation. The following general Fourier transform of these functions is obtained:

where C_n^λ and Y_lm represents the usual Gegenbauer polynomials and spherical harmonics, respectively. This unified analytical formula is valid for all the allowed values of integer n – l. Previous results, which are given in terms of the Gauss hypergeometric function ₂F₁, provide two separate expressions depending upon whether n – l is odd or even. A power series representation of the present result for _nlm^(α)(q) contains the vector q merely through regular solid harmonics _q^l Y_lm () and binomial terms (q² + α²)^−N, where N is a non-negative integer. This is particularly amenable to subsequent integrations over the vector q in multicenter atomic scattering integrals involving the momentum space Slater-type orbitals.

The correlated-configuration saddle point method is proposed as a tool for rather high accuracy determination of autoionizing states in atomic systems. The method is based on the method of superposition of correlated configurations, elaborated previously by one of the authors and on the mini-max principle. The positions of the six lowest ²P⁰ resonances in the lithium atom have been determined. The results are better than those obtained by other authors and a comparison with experiments is in general satisfactory.

The correlated-configuration saddle-point method recently proposed by the authors is used to calculate nonrelativistic positions of nine ²D resonances in the lithium atom. Elastic and inelastic scattering regions are taken into account. An extension of the method to describe resonances in the latter region properly is also proposed. The results obtained are in most cases better than those of other authors and an agreement with experimental data is rather good.

Ab initio calculations of the differential, integral and momentum transfer cross sections for collisions of electrons with neutral argon have been performed in the energy range 0.001-300 eV. The interaction of the e-Ar system is a sum of three spherical potentials namely, static, exchange and polarisation. The target electronic density function is obtained from a self-consistent numerical Hartree-Fock procedure. The various potential terms are then determined from this electron density function. The phase-shifts are evaluated using the variable-phase-approach. The present results involve no fitting parameter and compare very well with the experimental data at all energies considered here.

Absolute cross sections for the simultaneous excitation and ionization of Ar by electron impact have been measured by the optical method. In particular we report the measurements of eighteen levels belonging to the 3p⁴ 4p and 3p⁴ 4d configurations of Ar II. The dependence on electron energy of the excitation functions of some 3p⁴ 4p levels was studied in the range 0-6000 eV.

Radiative lifetimes of eleven argon II and krypton II levels have been determined using selective pulsed laser excitation and time resolved observation of the reemitted fluorescence. The laser excitation was performed from metastable Ar II and Kr II levels, populated by a pulsed low pressure hollow cathode discharge. The results are discussed with regard to trends in the behaviour of lifetimes along homologous series.

The Green's function scattering-theoretic method is used to study the ideal vacancies in the SnTe. The diagonal matrix elements of the Green's function are calculated using the Linear Combination of Atomic Orbitals method with the minimal basis set, all nearest-neighbor interactions and a second neighbor interaction. A good description of the valence and the conduction bands is obtained. The Sn vacancy is found to induce two holes in the valence bands and the Te vacancy two electrons in the conduction bands, in accord with the known experimental and theoretical results. Using the calculated Green's function and the specifics of the electronic structure of the IV-VI compounds, the changes in the electronic structure due to a substitutional impurity and the implications of the vacancies to the structural stability of SnTe and the other IV-VI compounds are discussed.

Barkhausen noise has been investigated in SiFe laminations in a wide range of magnetization rates (1.5 × 10⁻⁴ Ts⁻¹ ⩽ İ ⩽ 3Ts⁻¹). The statistical parameters of the noise are found to follow a complex non-linear dependence on İ. It is shown that, by means of a general theoretical approach to the motion of the Bloch wall, stochastically interacting with the surrounding medium, it is possible to make an accurate prediction of the Barkhausen noise power spectrum, which is found to be in good agreement with experiments.

Both boron-type and A1N-type high-permeability oriented silicon steel compositions have been case into 6.4 mm thick castings and successfully processed into well oriented finished products. The core losses for 0.30 mm steels ranged from 1.500 to 1.604 watts per kilogram at 60 Hz and 1.7 T (M-2H and M-3H quality levels). Texture development as indicated by B₈ was reasonably good lying between 1.875 and 1.901 Tesla.

The processing is of such a nature that an in-line process of melting, casting, solutioning and hot rolling is anticipated. Such a process would be less capital intensive and more energy efficient than existing methods of producing oriented silicon steels.

Microcrystalline ribbons of Fe-6.5 wt% Si alloy prepared by planar flow on Cu-Be wheel are used. Grain growth during isochronal annealing is measured. We confirmed by X-ray diffraction, transmission electron microscopy and Vicker's microhardness the different phase domains of A₂. B₂ and DO₃. Ordering kinetics are studied by Vicker's microhardness. DO₃ phase hardens the material whereas B₂ softens it. The effect of ordering on the magnetic properties as induction, coercive force, permeability and losses, is studied. H_c and P₁ decrease respectively from 112 to 20 A/m, and 4 to 0.7 mw/cm³ as grain diameter increases from 10 to 150 μm. μ_max increases from 3100 to 22000 for the same increasing of grain diameter. The ordering effect is smaller than the grain size one, so it does not show for 300 μm grain diameter samples. The order-disorder effect on magnetic properties is insignificant with regard to the grain size one.

Multipolar 180° Bloch walls are frequently observed in soft magnetic media. A critical curvature of these walls during the magnetization-reversal process causes the nucleation of 90° flux-closure domains which yield a considerable susceptibility decrease and provide a source of irreversibilities. The phenomenon has been investigated on iron-whisker single crystals by means of direct optical observations and inductive measurements.

Susceptibility measurements were performed on polycrystalline (nickel and Permalloys) and glassy (iron-nickel-boron-silicon) specimens of 50 mm length, around 1 mm width and 0.03-0.2 mm thickness. They demonstrate that the investigation on approach to saturation can give further information on structural properties. In crystalline case, the stress dependence of susceptibility gives reliable estimates for the magnetostriction and anisotropy constants of single crystals, whenever the susceptibility is separable χ(σ, H) = a(σ)F(H + H_A), where H_A is the effective anisotropy field. To get the magnetostriction constant in glassy alloys, similar relation should hold.

A new method is shown for determinating domain structures in scanning electron microscopes by using the backscattered electrons. The detectors are a pair of semiangular semiconductor diodes, and a special signal circuit is incorporated in the scanning electron microscope to enhance the picture of the magnetic domain wall structure. The method has been applied to metallic glasses of high magnetostrictive coefficient. After quenching, the "as received" ribbons exhibit a magnetic domain structure which is characteristic of the quenching process rather than the composition of the material. In addition, the method is able to give information about the domain wall thickness and the direction of the magnetization.

The results of laboratory investigations of the plasticities of Fe-Si-Al alloys are discussed in this paper. The rollabilities of these alloys were determined by a modified reverse bend test. The modification was that the reverse bend test was performed at different temperatures. The results reveal that rapid plasticity increases occur at particular temperatures, defined as "T_s". The "T_s" values are typical for individual alloys. It was found that alloys are plastic at room temperature if the chemical composition complies with the formula:

% Si + 0.54(% A1) ⩽ 3.5.

The plastic Fe-Si-Al alloy having the highest possible resistivity could be selected using the above formula.

The paper presents the results of application of permalloy thin film magnetoresistive sensors for investigation of silicon iron sheets. The following parameters have been measured - the single point value of magnetic field intensity and anisotropy, sheet texture, losses and uniformity. Determination of these parameters has been based on the measurement of stray field at the sheet surface.

The stability of a self-gravitating, perfectly conducting and compressible fluid cylinder has been elaborated. The dispersion relation of this configuration is derived in its general form. The magnetic field has always a stabilizing effect for all possible modes of perturbation. The gravitational instability becomes worse in the presence of the compressibility effects in the fluid.