bluuebunny/crossref_metadata_2025 huggingface dataset:
Pressure Ionization in Nonideal Alkali Plasmas
Authors: Ebeling W. , Meister C. V. , Sändig R. , Kraeft W.‐D.
Published: May 2007

A system of electrons (e) and ions (i) is considered in which beside the Coulomb interaction short range forces are taken into account, i.e. for the e‐i interaction a pseudopotential is used, and for the (classical) ions crystallographic radii are used.

For a Cesium plasma the thermodynamic properties are calculated quantumstatistically in a wide temperature‐density region. Degeneration effects are taken into account approximately. In the region with bound states the ionization equilibrium is discussed, and the Mott‐Transition is investigated critically. A phase transition occurs in the framework of the model chosen at Tc ≈ 4500 K and nc ≈ 4.1020 cm−3.
Die Berücksichtigung der Ionisation durch Elektronenstoß in der Elektronenkinetik des schwachionisierten anisothermen Plasmas. I. Analyse des Ionisierungsstoßintegrals und Ableitung von geeigneten Darstellungen für eine numerische Behandlung
Authors: Wilhelm J. , Winkler R.
Published: May 2007

Ausgehend von einer Bilanzierung der Elektronen im Geschwindigkeitsraum wird der Beitrag der Elektronenstoßionisierung zur Boltzmanngleichung der Elektronen bestimmt. Durch schrittweise Ausintegration des Ionisierungsstoßintegrals unter Einarbeitung des Impuls‐und Energiesatzes sowie der Kugelflächenfunktionsentwicklung der Geschwindigkeitsverteilungsfunktion der Elektronen wird die analoge Entwicklung des Ionisierungsstoßintegrals hergeleitet. Aus dieser werden die entsprechenden Beiträge zur Konzentrations‐und Energiebilanz der Elektronen gewonnen. Die Einarbeitung vereinfachender Annahmen über den differentiellen Streuquerschnitt beim ionisierenden Stoß ermöglicht die Ableitung von geeigneten Darstellungen des Stoßintegrals zur Bestimmungsgleichung der Isotropverteilung in einer Form darstellen, welche nur noch den totalen Ionisierungsquerschnitt enthält.
Long Wave Limit of the Complex Dielectric Function for Coulomb System with Bound States
Authors: Röpke G. , Meister C.‐V. , Kollmorgen K. , Kraeft W.‐D
Published: May 2007

For plasmas consisting of charged particles an improvement of the RPA dielectric function is considered which accounts especially for the possibility of the formation of bound states. The polarizability contains contributions of bound states as well as of scattering states. The imaginary part of the dielectric function describes optical transitions, and expressions for the electrical conductivity are obtained.
Problems of Separating Reaction Subchannels Demonstrated by a Multidimensional Study of the Reaction K−p → K* (890) Δ (1236) at 10 GeV/c
Authors: Naumann Thomas , Schiller H.
Published: May 2007

We investigate a subchannel which was separated by a cluster analysis and has the expected effective mass distributions, cross section, and angular distributions, but shows in the t‐dependence of spin density matrix elements strong influence of another subchannel. A cluster analysis helps to answer the question of overlap in multidimensional space.

We warn against considering cuts as efficient means of separation if physical analysis relies upon angular distributions. The effects of overlap and interference are shown to be important in this case.
Conductance Theory of Nonideal Plasmas
Authors: Ebeling W. , Röpke G.
Published: May 2007

The conductivity of nonideal plasmas is investigated by using the kinetic theory as well as the Kubo‐type correlation function theory. The effects of dynamical screening, short range forces and the Debye‐Onsager relaxation effect on the conductance problem are considered without and with quantum mechanical corrections. For some special plasmas it is found that deviations from Coulomb's law and quantum effects have only a small effect on the conductivity, whereas the numerically most important effects are connected with the dynamical screening and with the Debye‐Onsager relaxation force.
Streuung elektromagnetischer Oberflächen‐ und Volumenwellen an rauhen Oberflächen. Teil I. Allgemeine Grundlagen
Authors: Ponath H.‐E.
Published: May 2007

Es wird eine klassische Theorie der Streuung von elektromagnetischen Volumen‐ oder Oberflächenwellen an rauhen Oberflächen (Dielektrika oder Leiter) dargelegt. Die Erregerwelle erzeugt an der rauhen Grenzfläche eine Oberflächenpolarisation, die die Quelle für die Streustrahlung darstellt; sowohl in den Wellengleichungen als auch in den Grenzbedingungen für die Felder muß diese rauhigkeitsbedingte Polarisation berücksichtigt werden. Es werden allgemeine Ausdrücke für die Spektraldichten von Oberflächen‐ und Volumenstreuwellen angegeben, wobei die Erregung der Oberflächenpolarisation durch die Primärwellen sowohl homogen als auch inhomogen erfolgen kann.
Streuung elektromagnetischer Oberflächen‐ und Volumenwellen an rauhen Oberflächen. Teil II. Die Streulichtverteilung; Ein‐ und Auskopplung von Oberflächenwellen
Authors: Ponath H.‐E.
Published: May 2007

In dieser Arbeit erfolgt die Berechnung der Spektraldichte der Streustrahlung für die Streuung von Volumen‐ oder Oberflächenwellen an homogenen isotropen rauhen Oberflächen. In Abhängigkeit von den in den Medien z > O und z < O entstehenden Wellentypen wird eine Klassifikation aller möglichen Streuvarianten vorgenommen und die Winkelabhängigkeiten der verschiedenen Polarisationsvarianten (∥ und ⟂) der Streustrahlung ermittelt. Der Zusammenhang zwischen der Rauhigkeits‐Korrelationsfunktion und der Effektivität der Ein‐ bzw. Auskopplung von Oberflächen‐ und Volumenwellen wird diskutiert und ein Vergleich mit den Resultaten anderer Autoren angestellt.
Alpha Cluster in Hartree‐Fock Calculations
Authors: Hassan M. Y. M. , Moharram S. , Osman M. M.
Published: May 2007

Hartree‐Fock (HF) calculations have been performed fcr 12C nucleus assuming a trigonal D3h equilibrium configuration. Different aspects including symmetry, kinds of two‐body interactions are investigated. The HF calculations have been carried out using a velocity dependent effective potential of s‐wave interaction. The results are compared with previous calculations. In all HF calculations no deviation from axial symmetry is obtained.
An Analytical Calculation of the Equation of State and the Critical Point in a Dense Classical Fluid of Charged Hard Spheres
Authors: Ebeling W. , Grigo M.
Published: May 2007

A theoretical expression for the equation of state is developed which is based on the mass action law, the Carnahan‐Starling expression for the hard‐sphere contributions and the mean‐spherical approximation for the Coulombic interactions. Numerical calculations of the pressure and the critical data show good agreement with other methods (HNC, MC etc.).
On the Problem of Random Walk without Self‐intersections
Authors: Alkhimov V. I.
Published: May 2007

The particle random walk without self‐intersections in the n‐dimensional Euclidean space is investigated. The distribution function for the end‐to‐end distance of a walking particle trajectory is obtained up to the second order in the excluded volume V0.
Die Berücksichtigung der Ionisation durch Elektronenstoß in der Elektronenkinetik des schwachionisierten anisothermen Plasmas III. Das instationäre Verhalten bei großer impulsförmiger Feldstörung
Authors: Wilhelm J. , Winkler R.
Published: May 2007

Es wird das Zeitverhalten der Elektronenkomponente bei einmaliger impulsförmiger Störung des elektrischen Feldes im Plasma berechnet. Die Untersuchungen erfolgen am Beispiel des schwachionisierten Neon‐Plasmas, wobei neben elastischen und anregenden Stößen zusätzlich die Direktionisation durch Elektronenstoß sowie ein Elektronenverlustterm mit konstanter Lebensdauer in die Berechnungen einbezogen werden. Die Bestimmung der Zeitentwicklung aller interessierenden makroskopischen Größen der Elektronen erfolgt ausgehend von stationären Zuständen durch Lösung der zeitabhängigen Boltzmanngleichung. Neben der Berechnung der ausgeprägten zeitlichen Änderungen z. B. der Elektronenkonzentration, der Elektronenstoßfrequenzen für Anregung und Ionisierung und der einzelnen Energieübertragungsraten wird insbesondere das Relaxationsverhalten der Elektronenkomponente nach dem Ein‐ und Ausschalten der rechteckförmigen Feldstörung analysiert.
The Initial Process of Superfluorescence in Microscopic Description
Authors: Steudel H.
Published: May 2007

The initiation of superfluorescence is studied by a method starting from the N‐atom master equation in the high‐excitation limit. By numerical calculation cooperation numbers and the temporal growth of the radiation pattern are determined for atomic numbers between 24 and 48. For randomly distributed atoms there is a particle density of maximum cooperation.
Galilei Covariance Does Not Imply Minimal Electromagnetic Coupling
Authors: Kraus Karl
Published: May 2007

The postulate of Galilei covariance in one‐particle classical and quantum mechanics is reinvestigated, with particular intent to correct some current misconceptions concerning the rǒle of minimal electromagnetic coupling in Galilei covariant theories.
Grenzbedingungen der Elektrodynamik für Medien mit räumlicher Dispersion und Übergangsschichten
Authors: Wünsche A.
Published: May 2007

Ausgehend von den Maxwellschen Gleichungen der makroskopischen Elektrodynamik räumlich inhomogener anisotroper Medien mit räumlicher Dispersion werden mit einer wesentlich neuen Methode durch Benutzung von verallgemeinerten Funktionen und Momenteentwicklungen der Felder die Grenzbedingungen abgeleitet. Wir finden ein vollständiges unendliches System von Grenzbedingungen, das näherungsweise in endliche Systeme überführt werden kann. Für die Spezialfälle räumlicher Dispersion erster Ordnung und für Übergangsschichten erhalten wir in erster Näherung Grenzbedingungen, welche die üblichen verbessern und verallgemeinern.
Calculation of Oscillator Strength in the Sc I‐Spectrum
Authors: Siefart E.
Published: May 2007

The oscillator strengths of the main transition from the 3d 4s 4p‐states to the groundstate 3d 4s2 of Sc I are calculated on using wave functions derived by diagnolization of the interaction matrix elements of the 3d 4s 4p‐, 3d2 4p‐ and 4s2 4p‐configurations. The relevant dipole matrix elements are reduced by application of tensor algebra to the unknown one‐electron matrix elements 〈4s‖r‖4p> and <3d‖r‖4p〉. These radial integrals are calculated from experimental lifetimes and oscillator strengths as well as from theoretical models. The resulting absolute oscillator strengths show a fairly good agreement with the experimental data, the uncertainties being smaller than 10 percent for the strongest transitions.
Characteristic of Cluster Production in Hadronic Interaction in Emulsion at Accelerator Energy
Authors: Ghosh Dipak
Published: May 2007

Charakteristika der Cluster‐Produktion durch Hadron‐Wechselwirkungen in Emulsionen bei Beschleuniger‐Energien

In dieser Arbeit wird die Bestimmung der Größe der Cluster im Pionisierungsgebiet von Proton‐Nukleon‐Wechselwirkungen in Emulsionen bei 22,6 GeV/c dargestellt. Hierbei wird eine modellunabhängige Methode benutzt, die kürzlich in einer Arbeit von Shivpuri und anderen vorgeschlagen wurde. Es wurde beobachtet, daß bei Beschleuniger‐Energien ein Cluster aus maximal drei geladenen Teilchen (Pionen) besteht.
Space‐Dispersion Approach to the Explanation of the Higgs‐Mechanism
Authors: Papp E.
Published: May 2007

Proofs have been given that gauge transformations are needed in order to make finite the divergent space‐dispersions evaluations occurring as a result of the scalar‐field translation. So, the Higgs‐mechanism works only if there is a finite maximum value of the emerging space‐dispersion evaluation of the scalar field. The space dispersion thus used is expressed by the imaginary part of the average‐value of the non‐hermitian space‐operator.
Superharmonic Approximation for Crystal
Authors: Yukalov V. I.
Published: May 2007

The localized approximation for a quantum crystal considered earlier by the author is taken here as the initial step of an iteration, and the higher approximations for the propagators and thermodynamic functions are calculated. This generalization is based on a new type of a double iterative procedure for the equation of motion. The method is illustrated with a three‐dimensional crystal.
An Extensive Survey of the Characteristics of Pseudorapidity Distributions in Hadron‐Nucleus Collisions at High and Ultra High Energies
Authors: Ghosh Dipak
Published: May 2007

This paper presents an extensive study of the nature of the pseudorapidity distribution in hadron‐nucleus collision in emulsion from accelerator energy to super high cosmic ray energies (24 GeV/c to 4 TeV). The energy and the target dependence of the distributions and their possible significance are also discussed.
Shortening of the Energy Relaxation Time of Excited Molecular Vibrations of Small XH Molecules in a Dense Medium by Formation of H‐Bonds XH…Y
Authors: Mühle S. , Süsse K.‐E. , Welsch D.‐G.
Published: May 2007

By applying the models developed by Bixon and Jortner and by Konoplev and Plotnikov, respectively, for describing the energy relaxation of excited electronic levels and by using the results of the authors recently found from the study of the IR absorption spectra of H‐bonded species XH…Y the depopulation of excited vibrational levels of smal (two‐atomic) molecules in a dense medium (solid matrix) is studied. It is found that by formation of H‐bonds the depopulation times may be shortened essentially (more than five orders of magnitude).
Adjusting Conditions for High‐resolution Pulsed NMR in Solids
Authors: Döhler H. , Döhler T. , Fenzke D.
Published: May 2007

Adjusting conditions of pulse sequences for high‐resolution nmr in solids are demonstrated by the example of the WHH4 cycle. For this pulse sequence the well‐known adjusting condition [1] occurs as limiting case at sufficiently weak dipolar interaction. The relations between the pulse rotation angle and interval time proved to be dependent on the dipolar interaction. Therefore it is impossible to suppress the dipolar interaction in ordinary solids completely.

If the strength of the dipolar interaction varies in a range depending on the allowable inhomogeneity of the rf field a spectrometer for high‐resolution nmr in solids can be adjusted in an almost optimal way.
On the Decay Rate of Bound Muons
Authors: Chatterjee L. , Roy T.
Published: May 2007

The rigorous calculation of the Bound muon decay rate performed by Überall seems exhaustive. However an important effect not considered by him is the recoil of the nucleus.

The present paper reports the computation of the decay rate using a perturbative type of wavefunction, similar to that used by Überall. In addition, the nuclear recoil effect has been taken into account and the results, as expected, exhibit a light increase over Überall's values, in particular for the lighter elements, where recoil is more pronounced.

Screening by the atomic electrons and the effect of vacuum polarisation have also been considered, but eventually found to be negligible.
Lepton‐Pair Production in a Nucleon Field
Authors: Allam S. H. , El‐Kheshin M. , El‐Shawarbi A.
Published: May 2007

The total cross‐sections for the photo‐nucleon reactions y + p → p + v + v− and y + n → n + v + v− are calculated according to Weinberg‐Salam theory. The effect of the form factors is taken in the electromagnetic vertex. The dependence of the total cross‐sections on the energy of the incident photon is explicitly shown.
The Two‐Nucleon Stripping Process with Skyrme Type Potential
Authors: Osman Ahmed , Ismail M. Y.
Published: May 2007

Theory of two‐nucleon stripping reactions is reconsidered. The nucleon‐nucleon interactions are taken as Skyrme type potentials. Differential cross‐sections for two‐nucleon stripping reactions are calculated using DWBA approximation with different Skyrme type potentials of different parameters. The angular distributions for different two‐nucleon stripping reactions (t, p) with incident triton on the different targets of 31P, 40Ca, 96Zr, 118Sn and 206Pb are calculated giving good agreement with the experimental data. Better values are extracted for the spectroscopic factors.
On the Calculation of the Electrical Conductivity of a Nonideal Hydrogen Plasma
Authors: Blümlein J. , Kraeft W.‐D. , Meyer Th.
Published: May 2007

The electrical conductivity of a nonideal hydrogen plasma is calculated within the linear response formalism. The approximation given involves the first term with respect to the density expansion in the low degenerate case. The contributions of the free‐free scattering of the particles as well as the bound‐bound, bound‐scattering, and scattering‐scattering parts due to multiple scattering are discussed up to this level.
Quantum Mechanical Second Virial Coefficient for Cutoff Potentials
Authors: Schlanges M. , Kremp D. , Gau R.
Published: May 2007

The high‐ and low temperature approximations of the second virial coefficient for cutoff potentials are discussed and compared with numerical results.
Begründung einer Integralgleichung für die Bewegung eines strahlenden Elektrons
Authors: Petzold J.
Published: May 2007

Für eine früher als Bewegungsgleichung für ein strahlendes Elektron vorgeschlagene Integro‐Differentialgleichung wird eine Begründung auf der Grundlage der Maxwell‐Lorentz‐Theorie gegeben. In erster Näherung und im nicht‐relativistischen Grenzfall erhalten wir die Theorien von Herglotz (1903) und Kaup (1966).
Statistics in a Trilinear Interacting Stokes‐Antistokes Boson System
Authors: Tänzler W. , Schütte F.‐J.
Published: May 2007

The statistics of a system of four boson modes is treated with simultaneous Stokes‐Antistokes interaction taking place. The time evolution is calculated in full quantum manner but in short time approximation. Mean photon numbers and correlations of second order are calculated. Antibunching can be found in the laser mode and in the system of Stokes and Antistokes mode.
Statistics of a Stokes‐Antistokes Interacting Boson System with Damping
Authors: Germey K. , Schütte F.‐J. , Tiebel R.
Published: May 2007

The statistics of a system of four boson modes in Stokes‐Antistokes interaction is considered with respect to the influence of damping in one mode. The time evolution of the system is calculated. The mean particle numbers and the factorial moments of photon number distribution are calculated. Numerical results show strong dependence on bath temperature but only weak influence of the bath coupling strength. In the combined Stokes‐Antistokes system Antibunching appears if the bath temperature is low.
Hermitesche Relativitätstheorie, Chromodynamik und Confinement
Authors: Treder H.‐J.
Published: May 2007

Die Ausdehnung der Riemannschen Metrik der Allgemeinen Relativitätstheorie ins Komplexe bedeutet die Ersetzung der Symmetrie‐Bedingungen

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für den metrischen Tensor, Affinität und Ricci‐Tensor durch die Hermiteschen Bedingungen

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Mit diesen Bedingungen führt das Einstein‐Hilbert‐Hamilton‐Prinzip

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zu einer erweiterten Gravitationstheorie (Einstein), die im Sinne der EIH‐Approximation neben der Newton‐Einsteinschen Gravodynamik, auch die Chromodynamik der Elementarteilchenphysik enthält.

Die von den Einstein‐Schrödingerschen Feldgleichungen der Hermiteschen Relativitätstheorie implizierte Wechselwirkung zwischen Gravo‐ und Chromodynamik erzwingt das „Confinement”︁. Ohne dieses Confinement würde das Gravitationspotential divergieren, d.h., es könnte keine — nach Maßgabe der Einstein‐Schrödingerschen Feldgleichungen — Riemannsche Raum‐Zeit‐Metrik gik = aik geben.
Equilibrium Statistical Mechanics in Mach‐Einstein‐Universes
Authors: Mücket Jan P.
Published: May 2007

Within the framework of the Mach‐Einstein‐doctrine as formulated by TREDERthe thermodynamical quantities and the relations between them are derived for a simple N‐particle‐gas in equilibrium by means of a statistical‐mechanical description of the particle system. Because of the induction of inertia for each particle due to the gravitational interaction with all other particles the corresponding equations of state are modified essentially in some cases.
Über zweidimensionale Turbulenz
Authors: Szablewski W.
Published: May 2007

Aus der Gleichung der Turbulenzenergie bei zweidimensionaler Turbulenz folgt neben dem Transfer der Enstrophie und Turbulenzenergie in Richtung großer Wellenzahlen ein Energie‐ nd Enstrophie‐Transfer in Richtung kleiner Wellenzahlen für einen Bereich O < k < k1 (k Wellenzahl).

Es wird die der k−1‐Gesetzmäßigkeit des Spektrums der Enstrophie im Konvektionsunterbereich äqivalente Form des Enstrophietransfers abgeleitet. Auf dieser Basis erhalten wir für den Konvektionsbereich k≫ k0 (k0 Wellenzahl der großen Wirbel) in einfacher Form ein Ähnlichkeitsgesetz des Spektrums, das in der Asymptote eine logarithmische Modifikation der k−1‐Gesetzmäßigkeit enthält.

Für den viskosen Bereich bei großen Wellenzahlen ergibt sich ein exponentielles Abklingen des Spektrums.

Schließlich beschreiben wir auf der Grundlage des Transfers für den Konvektionsbereich k ≫ k0 approximativ den Übergang des Spektrums vom Konvektions‐ in den Zähigkeitsbereich. Die gewonnene Formel enthält sowohl das Ähnlichkeitsgesetz des Spektrums im Konvektionsbereich k ≫ k0 wie das exponentielle Abklingen des viskosen Bereiches.

Die mittels des Ähnlichkeitsgesetzes herzuleitenden Spektren des Enstrophie‐ und Energietransfers im Konvektionsbereich k ≫ k0 ergeben, daß hier – jeweils mit Null startend – der Transfer der Enstrophie zu großen Wellenzahlen hin und der Transfer der Energie zu kleinen Wellenzahlen hin erfolgt.
The Hertz's Method of Superpotential
Authors: Bleyer U. , Treder H.‐J.
Published: May 2007

The Method of HERTZ consists in the solution of the electromagnetic field equations by the help of a superpotential. We analyse the applicability of this method to more general field equations.
Effect of Fluctuation on Plane Front Propagation in Bistable Nonequilibrium Systems
Authors: Schimansky‐Geier L. , Mikhailov A. S. , Ebeling W.
Published: May 2007

A theory of front propagation in bistable stochastic media is developed. The effect of fluctuations is twofold: 1) they lead to random variations of the front shape. 2) they result in random motion of the front positions. Its general expression for the dispersion of the position for arbitrary stochastic noises with spatial correlation length lc and correlation time τc is given. For rate functions with cubic nonlinearities the dispersion formula is further analysed.
Derivation of the Finslerian Gauge Field Equations
Authors: Asanov G. S.
Published: May 2007

As is well known the simplest way of formulating the equations for the Yang‐Mills gauge fields consists in taking the Lagrangian to be quadratic in the gauge tensor [1 ‐ 5], whereas the application of such an approach to the gravitational field yields equations which are of essentially more complicated structure than the Einstein equations. On the other hand, in the gravitational field theory the Lagrangian can be constructed to be of forms which may be both quadratic and linear in the curvature tensor, whereas the latter possibility is absent in the current gauge field theories. In previous work [6] it has been shown that the Finslerian structure of the space‐time gives rise to certain gauge fields provided that the internal symmetries may be regarded as symmetries of a three‐dimensional Riemannian space. Continuing this work we show that appropriate equations for these gauge fields can be formulated in both ways, namely on the basis of the quadratic Lagrangian or, if a relevant generalization of the Palatini method is applied, on the basis of a Lagrangian linear in the gauge field strength tensor. The latter possibility proves to result in equations which are similar to the Einstein equations, a distinction being that the Finslerian Cartan curvature tensor rather than the Riemann curvature tensor enters the equations.
On the Renormalization Group Method for the Problem of Random Walk without Self‐Intersections
Authors: Alkhimov V. I.
Published: May 2007

Random walk without self‐intersections for a particle in the Euclidean n‐dimensional space is investigated. Renormalization group equations for the probability density of the end‐to‐end distance of a particle trajectory are derived. The asymptotics for this probability density are defined for 4 ‐ n ≪ 1.
Second Order Corrected Hadamard Formulae
Authors: Epele L. N. , Fanchiotti H. , Canal C. A. Garcia
Published: May 2007

The second order correction to the Hadamard formulae for the Green function, harmonic measures and period matrix of a two‐dimensional domain is obtained iu the context of the domain variational theory.
Examples of Finslerian Metric Tensors of the Space‐Time Signature
Authors: Asanov G. S.
Published: May 2007

Continuing the previous work [1], where a way of associating the gauge fields with Finslerian metrics has been indicated, in the present note we propose a class of Finslerian metrics which are of interest for the following two reasons. Firstly, the metrics give rise to the Finslerian metric tensors of the space‐time signature (+ − − −). Secondly, the associated indicatrices prove to be spaces of constant curvature, yielding examples of the Finslerian metrics which reflect the internal symmetry groups SU(2) and SU(2)⊗SU(2).
On the Nuclear Energy Generation Rate in a Simple Analytic Stellar Model
Authors: Haubold H. J. , Mathai A. M.
Published: May 2007

This paper is concerned with the hydrostatic equilibrium of a purely gaseous star generating energy at a rate . By the common technique of integration theory of special functions the total net rate of nuclear energy generation is evaluated analytically for a linear density distribution function assumed for a simple stellar model.
Gravitationsphysik und Lorentzraum
Authors: Burghardt R.
Published: May 2007

Für statische und stationäre Gravitationsfelder lassen sich koordinateninvariante Erhaltungssätze aufstellen. Die Erhaltungsgrößen werden im Lorentzraum dargestellt, sind einer physikalischen Interpretation zugänglich und umfassen Feld‐ und Materieterme. An einigen Modellen wird die Nützlichkeit des Verfahrens gezeigt.
Derivation of Absolute Depth‐Intensity Spectrum under Standard Rock from the Recently Estimated Primary Cosmic Ray Spectrum
Authors: Bhattacharyya D. P. , Pal Pratibha , Mukhopadhyay A.
Published: May 2007

Using the recently derived primary cosmic ray nucleon spectrum from JACEE and GSFC balloon flight data and Fermilab results for pp → π± + X anything inclusive reaction data in the light of Feynman scaling the depth‐intensity spectrum under standard rock has been estimated. A precisely constructed range‐energy relation has been applied in this analysis. The derived spectrum when corrected for range fluctuation agrees approximately with the experimental data under standard rocks measured by MIYAZAKI, BARTON, CASTAGNOLI et al., MEYER et al., BERGAMASCO et al., SHELDON et al. and BASCHIERA et al.
Noise Influence on a Dispersive Optical Bistable System with Trilinear Interaction
Authors: Germey K. , Herger R.‐L. , Herklotz R. , Mareyen M. , Schütte F.‐J. , Tiebel R. , Worlitzer K.
Published: May 2007

The influence of fluctuations in the driving fields on an optical bistable multimode system inside a ring resonator with a second order nonlinear material is considered. Steady state solutions of the resulting Fokker‐Planck equations are found for different approximations in which one or two of the modes can be eliminated adiabatically. The results of the stochastics are compared with the deterministic behaviour.
On Geometry of Point Defects and DislocationsThe Meaning of the Third Identity of Curvature Tensor
Authors: Günther H. , Zorawski M.
Published: May 2007

The aim of this paper is to proof mathematically that, as far as flat space geometry is considered, there is no geometrical interaction between point defects and dislocations. Point defects giving rise to non flat geometry have a more general geometrical structure. In this case the so called third identity of the curvature tensor starts to play an important role.
Gravitational Interaction of Fermion Antisymmetric Tensor Fields
Authors: Ivanenko D. , Obukhov Yu. N.
Published: May 2007

We investigate the coupling of classical and quantum antisymmetric tensor fields, which describe fermions, with the gauge gravitational field. We show that within the framework of the classical Einstein‐Cartan theory the new generalized nonlinear fermion theory can be formulated, which turns out to be the correct microscopic description of the Weyssenhoff spinning fluid. The oneloop gravitational counterterms and the conformal stress tensor and the axial vector current anomalies are obtained. The differences between the antisymmetric tensor fermions and the usual Dirac spinor fields are discussed.
Electric Quadrupole and Magnetic Dipole Moments of Mirror Nuclei and Self‐Conjugate Nuclei
Authors: Zickendraht W.
Published: May 2007

A transformation, which brings about the unification of the nuclear collective and single particle models, yields sumrules for the magnetic dipole moments and for the electric quadrupole moments of mirror nuclei. These sumrules are applied to cases, for which the numerical values of these moments are known.
Bemerkung über die maximale Energie eines Teilchens bei einem Drei‐Teilchen‐Zerfall
Authors: Kamke D.
Published: May 2007

Es wird gezeigt, wie die nicht‐relativistische Bedingung für die maximale Energie eines Teilchens ‐ bei gleicher Geschwindigkeit aller übrigen Teilchen ‐, abgeändert wird, falls eines oder mehrere Teilchen verschwindende Ruhmasse haben.
Ein Demonstrationsversuch zur Hyperfeinaufspaltung von Atomen
Authors: Schmitzer A. , Bechtel H. H. , Fick D.
Published: May 2007

Der Nachweis der laserinduzierten Resonanzfluoreszenz an einem thermischen Atomstrahl erlaubt auf einfache Weise die Beobachtung der Hyperfeinaufspaltung im Grund‐ und angeregten Zustand von Natrium. Ein für Demonstrationen geeigneter Versuch kann, neben dem Atomstrahl selbst, die Wirkung von Elektronen‐ und Kernspin im Hörsaal vorführen. Das benötigte Laserlicht wird hierbei über ein Lichtleiterkabel vom Labor in den Hörsaal geführt. Der Versuch kann auch zur Demonstration des optischen Pumpens und durch Anlegen eines Magnetfeldes in der Beobachtungsregion zur Demonstration des Zeeman‐Effektes benutzt werden.
Plasmadiagnostik mit Lithiumatomstrahl‐aktivierter Umladungsspektroskopie
Authors: Aumayr Friedrich , Winter Hannspeter
Published: May 2007

Durch Injektion von Lithiumatomstrahlen in ein magnetisch eingeschlossenes Plasma können dessen Protonen bzw. darin enthaltene Verunreinigungsionen über die infolge inelastischer Ion‐Lithiumatom‐Stöße resultierende charakteristische Linienstrahlung nachgewiesen werden. Mit Wirkungsquerschnitten bzw. zugehörigen Reaktionsratenkoeffizienten für die maßgebenden atomaren Anregungsprozesse wurden Berechnungen der Lithiumstrahlabschwächung sowie der Abstrahlcharakteristiken für die LiI 670,8 nm ‐ und Hα 656,3 nm ‐ Emissionslinien längs der Plasmarandschicht durchgeführt. Die Ergebnisse demonstrieren die Durchführbarkeit geplanter plasmadiagnostischer Messungen von Dichte, Temperatur und Driftgeschwindigkeit für Protonen sowie Verunreinigungsionen.
Über Anwendungsmöglichkeiten der PIXE‐Methode in der Luftstaubanalytik
Authors: Richter F.‐W.
Published: May 2007

Die Methode der protoneninduzierten Röntgenemission (PIXE) ist ein inzwischen anerkanntes Verfahren zur quantitativen Bestimmung von Spurenelementen.

Es wird gezeigt, daß PIXE für die routinemäßige Elementanalyse von Luftstaub‐Filterproben eingesetzt werden kann, insbesondere daß diese Methode in Verbindung mit zeitauflösender Luftstaubsammlung die Möglichkeit eröffnet, kurzzeitige Schwankungen der Elementkonzentrationen in der Luft zu erfassen.
Phasenmodulierte Anregung eines optisch gepumpten Spinsystems
Authors: Cappeller U. , Müller H.
Published: May 2007

Unter der Einwirkung von larmorfrequenten phasenmodulierten magnetischen Wechselfeldern treten in einem Spinsystem resonante „Kollektiv‐Rabi‐Bewegungen”︁ auf; diese Bewegungsformen sind besonders ausgeprägt, wenn der Phasenhub, die Wechselfeldstärke und die Phasenmodulationsfrequenz eine weitere charakteristische Bedingung (hier als „Rabi‐Resonanzbedingung”︁ bezeichnet) erfüllen.
Ergodicity and Entrainment in a System of Electrical Relaxation Oscillators
Authors: Grossmann S. , Schnedler E. , Thomae S.
Published: May 2007

We consider a system of two coupled relaxation oscillators. This model has been suggested, incorrectly, by other authors as a simple model of chaos. We show that this system is at most ergodic but never mixing. The spectra of both oscillators can be understood in terms of a mutual phase modulation. Finally we include entrainment effects in our description and compare our results with some measurements performed on an electric circuit.
Robert Rompe und die Wissenschaftspolitik der AdW der DDR
Authors: Hofmann Ulrich
Published: May 2007

Persönliche Bemerkungen über die Wissenschaftspolitik der AdW der DDR, ihre historische Entwicklung und Bedeutung für die gesellschaftliche Praxis.
The d−3 Law Describing the Thickness Dependence of the Electrical Resistivity of Rough Metal Films
Authors: Finzel H.‐U. , Wissmann P.
Published: May 2007

The resistivity of thin metal films with rough surfaces is higher than that of smooth films. This roughness effect is calculated assuming that the deviations of the thickness from a mean value are symmetrical. The total resistivity is found to be composed of the normal bulk resistivity, the wellknown contribution of the scattering of conduction electrons at the grain boundaries and surfaces, and an additional resistivity term due to roughness, which varies proportional to 1/d3. The theory is applied to polycrystalline nickel films deposited at ambient temperature under UHV conditions on glass substrates.
Equations of Motion for Test Particles in a Poincaré Gauge Field
Authors: Fuchs Helmut
Published: May 2007

We consider the equations of motion for test particles with internal structure in a Poincaré gauge field by a general Lagrangian approach. The break down of the Poincaré symmetry is also considered with respect to the equations of motion.
Schmidtsystem mit geebnetem Bildfeld durch Anwendung eines Hologrammspiegels
Authors: Glaubitz U. , Haferkorn H.
Published: May 2007

Die Bildfehlertheorie dritter Ordnung bietet die einzige Möglichkeit, die Abbildungsleistung optischer Systeme nach analytischen Formalismen gezielt zu verbessern. Es wurden Gleichungen für die Bildfehlerkoeffizienten von Hologrammspiegeln aufgezeigt, die speziell für die Konstruktion mehrgliedriger rotationssymmetrischer Systeme geeignet sind. Sie sind Teil eines geschlossenen Formelsatzes für konventionelle und holografisch abbildende Elemente. Die Interpretation führte zur Dimensionierung eines „Petzvalspiegels”︁, der selbst keine Brechkraft besitzt und dennoch eine Petzvalwölbung verursachen kann. Durch diese Eigenschaft wurde die Berechnung eines zweigliedrigen Spiegelsystems möglich, bei dem sämtliche Bildfehler dritter Ordnung kompensiert sind.
Verallgemeinerte Mastergleichungen und Fokker‐Planck‐Gleichungen für Prozesse in inhomogenen Systemen weitab vom Gleichgewicht
Authors: Haberlandt R.
Published: May 2007

Unter Verwendung verallgemeinerter kanonischer Gesamtheiten werden verallgemeinerte Mastergleichungen und Fokker‐Planck‐Gleichungen für irreversible Prozesse in inhomogenen, räumlich und zeitlich nichtlokalen Systemen, die weit vom Gleichgewicht entfernt sein dürfen, hergeleitet. Ihr Zusammenhang mit Spezialfällen wird diskutiert.
Aktuelle Fragen der Beziehungen zwischen Grundlagenforschung und industrieller Vorlaufforschung
Authors: Müller Kh.
Published: May 2007

Grundlagenforschung und industrielle Vorlaufforschung vergleichend werden ihre Unterschiede und notwendigen Gemeinsamkeiten diskutiert. Kriterien für eine gute Wechselbeziehung werden in „Elementarforderungen”︁ zusammengefaßt, die beide, Grundlagenforschung und industrielle Vorlaufforschung, streng zu beachten haben.
Gruppentheoretische Invarianten für Fehleruntersuchungen in der quantitativen Texturanalyse
Authors: Matthies Siegfried
Published: May 2007

Nach einem kurzen Überblick über Anliegen und Probleme der quantitativen Texturanalyse werden Fragen der Fehleranalyse behandelt. Es wird gezeigt, daß bestimmte Invarianten, die aus der Kristallsymmetrie folgen, dazu herangezogen werden können.
Zur Realisierbarkeit akustischer Quantengeneratoren auf der Basis supraleitender Tunnelelemente
Authors: Otschik Peter , Lange Felix
Published: May 2007

Es wird gezeigt, daß ein akustischer Quantengenerator bei Schmalbandtunnelinjektion von Quasiteilchen in einen Supraleiter bei Erfüllung einer Reihe physikalischer und technischer Bedingungen realisierbar ist. Diese betreffen die Erzeugung der Besetzungsinversion n(E) > 1/2 und eines positiven Verstärkungsfaktors der Phononen, die Herstellung einer sehr dünnen Tunnelbarriere und eines Resonators mit einstellbaren Eigenschaften des akustischen Spiegels und sehr kleiner lateraler Dimension in der Größenordnung der Kohärenzlänge. Die Realisierungschancen dieser Bedingungen werden ausführlich diskutiert.
The Influence of Quantum Effects on the Ferroelectric Properties of TSCC‐Type Single Crystals
Authors: Windsch W. , Braeter H.
Published: May 2007

Experimental investigations on tris‐sarcosine calcium chloride (TSCC)‐type crystals reveal that pure TSCBr and TSCJ are quantum paraelectrics. Measurements of the concentration dependence of phase transition temperature and order parameter, of the pressure dependence of phase transition temperature and of the shift of permittivity peak due to an external electric field show a pronounced influence of quantum fluctuations on the behaviour of these crystals. Based on the model of coupled anharmonic oscillators it is possible to describe all essential ferroelectric properties of the crystal system using only few model parameters in consistent manner. The proposed model can be successfully applied to other quantum paraelectrics.
Solution of the Nonlinear Equation of Motion of Relativistic Positrons under Planar Channeling Conditions
Authors: Wedell R.
Published: May 2007

In earlier publications the positron planar channeling at relativistic energies was often described by a harmonic potential. In this paper a system of differential equations describing the channeled positron motion in an anharmonic potential is derived. It is shown that at such small depths, where the statistical equilibrium is not established, the radiation energy loss may be neglected. The obtained simplified equations are equivalent to corresponding expressions for ion channeling at small depths. Therefore, these earlier results can also be extended to the positron case.
Zur Relaxationszeit des Kosmos
Authors: Treder H.‐J.
Published: May 2007

Die Relaxationszeit, die den Übergang vom Zustand der isotropen Turbulenz in den des mikroskopischen Chaos beschreibt, wird für den expandierenden Kosmos abgeschätzt.
Color Conductivity at High Resolution: A New Phenomenon of Nuclear Physics
Authors: Nachtmann O. , Pirner H. J.
Published: May 2007

In this paper we discuss in detail the hyothesis that nuclei show extended quark and gluon modes when explored with a high resolution probe. We call this color conductivity at high resolution. We relate color conductivity to the behaviour of proton‐proton total and elastic cross sections at high energies. For deep inelastic muon‐nucleon scattering we discuss in detail the nuclear evolution equation following from color conductivity and introduced by us previously. The EMC Fe/d data are well described by our theory if due allowance is made for the quoted systematic error. We predict striking effects from color conductivity in the final state of deep inelastic lepton‐nucleus scattering. The possibility of making fundamental tests of quantum chromodynamics in leptonnucleus scattering is emphasized. We connect the shadowing phenomenon to the volume and surface terms in the Bethe‐Weizsäcker formula for the nuclear binding energy. Finally we point out that deep inelastic scattering on deformed nuclei may be crucial to distinguish between different theories of the EMC effect.
Analytical Results Connecting Stellar Structure Parameters and Neutrino Fluxes
Authors: Haubold H. J. , Mathai A. M.
Published: May 2007

This paper is an attempt to construct simple analytic models to study the internal structure of main sequence stars. Explicit closed form expressions, which are computable, are given for a number of quantities such as nuclear reaction rate, luminosity, and the number of two particle reactions when the radial matter density of the stellar model is a nonlinear function decreasing from the center to the surface. All analytic results are obtained by taking advantage of the integration theory of generalized hypergeometric functions.
Particle Production in Non‐equilibrium Thermodynamic States in Nucleus‐Nucleus Collisions
Authors: Hussein M. T. , Hassan N. M. , Osman O. M.
Published: May 2007

The formation of nonequilibrium thermodynamic system is assumed during the collision of relativistic heavy ions with target nuclei. A simple classical solution of the Boltzmann equation is found and compared with the spectra of particles produced in the Ne‐U238 reaction at lab. energies of 250 and 400 MeV per nucleon. The model contains only one fitting parameter tc which is the time required by the system to reach the equilibrium state.
Über Spin‐3/2‐Felder in Raum‐Zeiten mit Torsion
Authors: Spinosa Ricardo
Published: May 2007

Ein geladenes massives Materiefeld mit Spin 3/2 wird im Rahmen der Riemann‐Cartanschen Geometrie ohne Anwendung der üblichen Rarita‐Schwingerschen Formulierung beschrieben. Die 2‐spinoriellen, speziell relativistischen Fierz‐Pauli‐Gleichungen für Spin‐3/2‐Felder werden in 4‐Spinor‐Formulierung ausgedrückt. Dies führt zu einer Spin‐3/2‐Lagrange‐Funktion, die zur Rarita‐Schwingerschen äquivalent ist. Alle drei Paare der 2‐Spinor‐Gleichungen ergeben sich als nicht äquivalent und für eine vollständige Beschreibung des Spin‐3/2‐Feldes notwendig. Die Riemann‐Cartansche Formulierung dieser Feldgleichungen läßt die Ursache von einer von H. A. Buchdahl festgestellten Inkonsistenz ihres Riemannschen Ausdrucks deutlich werden: keine Symmetrie der 2‐Spinoren soll vor dem Variationsverfahren angenommen werden.
Functional Integral Approach to a Many Fermion System with Bound States
Authors: Blaschke D. , Röpke G. , Reinhardt H.
Published: May 2007

The equation of state for a dense system of interacting Fermions is derived using functional integral technique. To investigate the formation of bound states, a Hubbard‐Stratonovich transformation is applied which expresses the action as functional of pair fields. The evaluation of the partition function in lowest orders with respect to the pair fields leads to a result which can be interpreted as the contribution of two‐particle states, accounting for density corrections as Pauli blocking and self‐energy shift. Comparison is performed with results for the equation of state of hot dense matter (plasmas, nuclear matter) obtained within a Green's function approach.
Phenomenology of Late Stages of Kaluza‐Klein Cosmologies
Authors: Bleyer U. , Liebscher D.‐E.
Published: May 2007

We consider the arguments to additional space dimensions in a general scheme of phenomenological cosmology, and show, that strong conditions are to be met.
Zur Quantisierung der Kosmologie
Authors: Treder H.‐J.
Published: May 2007

Die dynamische Quantisierung der Friedmannschen kosmologischen Gleichung führt zu der Aussage, daß die physikalische Interpretierbarkeit der Quantenkosmologie bereits in Fermischen Dimensionen zusammenbricht.
Dissipative Model of the Universe
Authors: Molnár P. , Mészáros M.
Published: May 2007

In the present study a trial is carried out to generalize the non‐relativistic‐dynamic model of cosmology put forward by O. Heckmann. The generalization is performed under the framework of the Gyarmati principle of irreversible thermodynamics for anisotropic inhomogeneous and viscous case. The equation of motion of the dissipative Universe will be a Navier‐Stokes tensor equation leading to a Riccatian differential equation general in one dimension. The equations of the Heckmann model compatible with standard cosmology can be obtained from this by means of further simplifying assumption.
On the Valence State of Iron in Sr0.52+Ca0.52+Fe0.54+ Me0.54+O32−
Authors: Fayek M. K. , Elnimr M. K. , El Hamalawy A. , Sekina M. Abou
Published: May 2007

Powder samples of Sr0.5Ca0.5Fe0.5Me0.5O3 (Me = Co, Zr or Mn) and Sr0.3La0.7FeO3 are investigated by X‐ray diffraction and Mössbauer effect spectroscopy.

Analysis of the completely ordered spectra suggested three kinds of iron ions coexist in general where the resolution into the different valence state is clearly seen. The Mössbauer effect parameters values are found to be close to those expected for Fe3+, Fe4+ and Fe5+ indicating that some of the tetravalent iron ions in its high spin state disproportionate into Fe3+ and Fe5+ ions passing through temperature dependent intermediate valence states.
The Influence of Supplementary Conditions for Papapetrou Equations on the Lyapunov Stability of Motion
Authors: Bakhan'kov A. A. , Ryabushko A. P.
Published: May 2007

The Lyapunov stability of circular motions of spinning test bodies in the Schwarzschild field has been considered. For Papapetrou equations the generalized supplementary conditions S0iu0 = kSijuj = k const, i, j = 1, 2, 3, have been chosen. Four of the first integrals of motion have been indicated. With the aid of Lyapunov functions the domains of stable motions have been found.
Effect of Surface States on the Electrochemical Behaviour of Single Crystal n‐ZnSe Photoelectrode
Authors: El‐Dessouki M. S. , El‐Kabbany F. , Attia V. A.
Published: May 2007

Surface Photovoltage Spectroscopy (SPS) technique has been used to detect the surface states of ZnSe (110) surfaces. Aqueous electrolyte/ZnSe junction has been electrochemically investigated in dark and under illumination. The effect of surface states on the kinetics of charge transfer through the semiconductor‐electrolyte (S/E) junction has been discussed. The low leakage and photocurrents measured by the application of D.C. bias were referred to the blocking nature of S/E interface, in which the localized and induced surface states play an important role.
The Mie Scattering at an Inhomogeneous and Arbitrary Shaped Inclusion
Authors: Rennert P.
Published: May 2007

We consider the scattering of an electromagnetic wave at an inhomogeneous and arbitrary shaped inclusion describing the inclusion as a non‐spherical perturbation. Thus, inhomogenety and arbitrarity in the shape are treated on the same footing. The fields are developed into vector spherical harmonics. The radial parts must be calculated from a coupled set of equations using the methods known from the scattering of a scalar field at a non‐spherical potential. Using an operator notation the lengthly expressions can be avoided, which contain the Clebsch‐Gordan coefficients.
An Inverse Problem for the Benney‐Kaup System ‐ Periodic and Decaying Case
Authors: Roy Chowdhury A. , Purkait Sasanka
Published: May 2007

We have formulated the inverse problem for the Benney‐Kaup system in both the case of asymptotically decaying and periodic solution. In the former we set up the Gelfand‐Levitan‐Marchenko equation and study the analytic properties required therein. In the latter case we prove that the nonlinear field can be determined by the Abel inversion on a Riemann surface with the help of elliptic or theta functions.
On the Vacuum‐Interaction of Two Parallel Cosmic Strings
Authors: Bordag M.
Published: May 2007

Cosmic strings are well known solutions of the Einstein equations. In classical physics there is no interaction between such strings. In quantum physics there is an interaction due to vacuum fluctuations like the well known Casimir effect. The interaction energy is calculated in the case of two parallel cosmic strings and shows an attractive force between them.