The possibility of using a semiconductor thermal probe to investigate the power flow distribution in waveguides

Conclusions

1. The temperature profile of an absorbing film for a given microwave power flux distribution has been considered.
2. The conditions under which agreement is found between the temperature relief and the flux distribution has been clarified.
3. An experimental investigation has been carried out of the temperature profile in a matched film for the TE₁₀ mode.
4. The possibility of using a semiconductor thermal probe to investigate the microwave power flux distribution has been demonstrated.

     

Symmetrieeigenschaften achtkomponentiger Spinorfelder im Gitterraum

Starting from the four component Dirac equation for free particles without mass W.Heisenberg und W.Pauli have shown that the interaction term is uniquely defined, if one requires that all symmetries of free particles are preserved. Here we obtain similar results if we start from the eight component Dirac equation for free particles without mass:

1. The symmetry group of the eight component Dirac equation for free particles without mass has 16 parameters. It is isomorph to the direct product of the SU 4 and a one-parametric group: SU 4× (1).
2. The interaction operator is uniquely defined if one requires to preserve as many symmetries as possible of those given in (1).
3. But some of the symmetries in (1) are necessarily broken, in particular that of SU 3. The symmetry of the interaction operator is given by SO 4× (1)× (1).

These results mean:

1. The Heisenberg theory is uniquely defined, only if one assumes that the free particle part of the equation is well known.
2. The theory can be changed without modifying the fundamental idea ofHeisenberg andPauli to deduce an uniquely defined interaction operator if one starts with a modified free particle part.
3. A special kind of modification of the free particle part leads essentially to the SU 4-symmetry including that of SU 3, which is necessarily broken by the interaction term.
4. The question arises if this break of the SU 3-symmetry has something to do with the real break. This question is not yet touched in this paper.

     

On the particle density of mass zero bosons and energy density of mass zero fermions

It is shown that even nonlocal generalizations of the usual expressions for

1. the particle probability density of mass zero, spin zero (one) bosons;
2. the energy density of mass zero spin one half fermions;

can become negative, indicating that the method of obtaining positive definite expressions for massive particles^2,4 for the above quantities does not work here.     

An investigation of the axial mode behaviour of a helical TEA-CO2 laser

The frequency behaviour of axial modes was investigated during the initial phase of mode competition in case of a helical TEA-CO₂ laser. With the help of a homodyne technique single-shot and multi-shot beat spectra were measured. Analysing these under various aspects and combining the results of an earlier investigation it was found that

1. inferior modes exist only for 100–200 ns.
2. their spectral width is less than 1 MHz and is determined by lifetime broadening, with the dominant mode narrower than 0.77 MHz,
3. in the average over many shots the spectral envelope of modes does not follow a Lorentzian shape as expected for the Lorentzian gain curve,
4. the beat powers change widely from shot to shot, whereas the total laser power remains constant,
5. no specific phase structures are likely to govern the laser emission, although the maximum emission principle appears to be obeyed with every individual shot. In an appendix relations are derived and summarized which are required for the evaluation of beat mode spectra and for the determination of line width as they apply to the actual time dependence of the laser emission.

     

Astroparticle physics with high energy neutrinos: from AMANDA to IceCube

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 10²⁰ eV and 10¹³ eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the science reach of its extension, IceCube. Similar experiments are under construction in the Mediterranean. Neutrino astronomy is also expanding in new directions with efforts to detect air showers, acoustic and radio signals initiated by super-EeV neutrinos. The outline of this review is as follows:

Introduction

Why kilometer-scale detectors?

Cosmic neutrinos associated with the highest energy cosmic rays

High energy neutrino telescopes: methodologies of neutrino detection

High energy neutrino telescopes: status

     

New interferometric method for determining the refractive index of thin dielectric film,its thickness,the phase shift,and the order of interference

A new interferometric method is proposed, using white light fringes of equal chromatic order to determine simultaneously the following paramcters:

1. The refractive index of a thin dielectric film, and hence its dispersion.
2. The film thickness.
3. The correct value of the order of interference.
4. The phase shift occuring due to reflection at the dielectric/metal interface. In the present work, doubly silvered zinc sulphide (ZnS) thin dielectric film was used as an example in applying the proposed method.

     

Bestimmung der wahren Halbwertsbreite derMζ-Linien der Elemente 38 Sr bis 47 Ag

1. The intensity distribution of theMζ-lines (40<λ<110Å) was measured using a 2m concave grating spectrometer.
2. The instrumental profile of the spectrometer could be determined by solving a modified folding equation by the method of successive approximations. For the spectrometer used we found that the instrumental response was a Gaußian, and that its width is independant of wavelength.
3. A graphical method is applied by which the natural width of theMζ-lines can be determined if the instrumenta profile is a Gaußian. Widths for Sr, Ru, Rh and Ag are presented for the first time.

     

Dynamical enhanced electron emission and discharges at contaminated surfaces

Broad-area electrodes show electron emission already at electric field strengthsF≈10⁷ V/m. This enhanced field emission (EFE) occurs only for contaminated surfaces. EFE is accompanied by photon emission and gas desorption yielding finally discharges. EFE is caused by dust and contaminants initiating the following effects:

an electron is stochastically emitted in a trigger zone

the electron gains energyΔE?eΔxF ^*

which excites electronic states

which relax by the emission of electrons, photons, and atoms

where the positive charges left behind enhanceF ^*=βF (β?1) initiating so an electron avalanche, i.e., a high conductivity channel. Because of charge migration and neutralization, this avalanche has a life time. This pulsating EFE is accompanied by light emission and gas desorption yielding finally a gas cloud and a discharge.

The pulsating, self-sustained EFE has the same root as:

the enhanced secondary emission found first by Malter

the conductivity switching exhibited by thin (≈ 1 μm) layers of semiconductors or insulators

the normal cathode fall and

the firing-wave instability in neurodynamics.

     

Nanoparticle and Nanoporous Carbon Adsorbents for Removal of Trace Organic Contaminants from Water

Removal of a wide range of trace organic contaminants from water to concentrations below USEPA Maximum Contaminant Levels (MCL) remains an important goal for the water industry. Design of advanced carbon based adsorption systems represents a unique approach to solving these problems. A number of successful examples are cited in this paper and are briefly summarized in the following section.

1. Removal of foulants such as humic acid using nanoparticle carbon blacks and chemically activated nanoporous fibers;
2. Removal of trace organic contaminants such as benzene, toluene, ethylbenzene and p-xylene (BTEX) to levels below USEPA MCL using nanoporous carbon fibers;
3. Removal of trace chemical warfare simulants such as diisopropylmethyl phosponate and chloroethylethylsulfide using enlarged nanoporous carbon fibers;
4. Removal of trace chlorinated solvents such as trichloroethylene (TCE) and chloroform using tailored nanoporous carbon fibers;
5. Removal of the trace herbicide, atrazine, to below USEPA MCL level using nanoporous chemically activated fibers.

In this paper the enormous improvement of the above systems over commercially available products in static and dynamic adsorption evaluation is described.     

Absence of singular continuous spectrum for certain self-adjoint operators

We give a sufficient condition for a self-adjoint operator to have the following properties in a neighborhood of a pointE of its spectrum:

1. its point spectrum is finite;
2. its singular continuous spectrum is empty;
3. its resolvent satisfies a class of a priori estimates.

     

Bestimmung von Stoßfrequenz und Stoßmodell in verschiedenen Flammenplasmen aus Absorption und Dispersion von Mikrowellen

The electron collision frequencies for four flames of different temperature and composition have been determined by means of measuring simultaneouslyX-band microwave attenuation and phase shift, which originate from the complex conductivity of the flame plasma. Hence the method can also be used for the determination of the collision frequencies of time dependent plasmas. In order to enhance the small magnitude of the quantities to be measured one hundred equal flames burnt inside the waveguide. The measurements show:

1. In flames collisions of electrons with induced dipoles dominate (Lorentz-theory).
2. The collision frequencies depend on the flame temperatureand on the chemical composition.

     

Magnetostriction measurement by means of strain modulated ferromagnetic resonance (SMFMR)

A novel method for measuring magnetostriction constants is presented. A strain, periodic in time, applied to the sample, causes a modulation of the ferromagnetic resonance line position. The height of the signal obtained after phase-sensitive detection is proportional to the strain modulation depth. The appropriate magnetostriction constant λ is obtained by comparing the height of the SMFMR signal with that of the FMR line, as recorded by means of magnetic field modulation. Features of the new technique are:

1. high sensitivity: λ_min? 10_?9 forM=100 Oe and linewidth ΔH _d=1 Oe;
2. λ's belonging to distinct precession modes are separately determined;
3. applicable to thin layers for which strain gauge techniques cannot be used;
4. wide temperature range: 1.2 K<T<300 K;
5. uniform stress.

An illustrative example (YIG layer on GGG substrate) is given.     

Existence of phase transitions for quantum lattice systems

We prove that the following lattice systems:

1. anisotropic Heisenberg model,
2. Ising model with transverse magnetic field,
3. quantum lattice gas with hard cores extending over nearest neighbours,

exhibit phase transitions if the temperature is sufficiently low and the transverse (or kinetic) part of the interaction sufficiently small.     

Two-dimensional quantum field theories containing a massless scalar field

The following new findings are briefly reported:

1. A consistent quantum theory can be formulated for a free massless scalar field in two-dimensional spacetime.
2. Satisfactory operator solutions in terms of asymptotic fields can be constructed in the Thirring and Schwinger models.
3. Gauge invariance is spontaneously broken in the Thirring model as well as in the Schwinger model.

     

The moment of inertia at the saddle point of low energy fission of even-even nuclei

We use the molecular model of low energy fission, which describes the nucleus by two interacting fragments, to calculate the moment of inertia for U²³⁶ in the cranking approximation including BCS theory. We show that the moment of inertia at the saddle point:

1. depends almost linearly on the fragment distance.
2. is influenced only very weakly by the pairing constant and by the fragment deformations.
3. shows, as a function of the distribution of mass between the two fragments (A ₁ ,A ₂ ), a minimum near the magic configurationA ₁=132,Z ₁=50 and depends in this mass region strongly on the term structure near the Fermi energy.
4. is approximately that of a rigid body.

     

Some current challenges in space plasma physics

An overview of the subject of space plasma physics is attempted. This encompasses a discussion of various ground-based and satellite studies of the near-Earth space environment, with its marked temporal and spatial variations, theoretical investigations, and numerical simulations. The important distinction is drawn between passive studies of elements of the natural system, aimed at the difficult task of understanding the self-consistent evolution of some natural processes, and active investigations, which either probe or modify natural processes, in order to improve understanding of cause and effect (e.g. of energy transformations) within the system. Linear, nonlinear, and chaotic processes can occur. Attention is paid to:

1. Energetic events on the Sun,
2. Large-scale features of the interplanetary medium, both observed directly and via scintillations of distant radio stars,
3. The magnetosphere in general, and the aurora in particular,
4. Wave-particle interactions, especially cyclotron resonance phenomena, and
5. The ionosphere, particularly when heated by powerful radio waves.

The approach adopted is to place these special topics in the context of the Solar Terrestrial Energy Program (STEP) of ICSU's SCOSTEP. Finally, mention is made of some benefits to humanity of studies of space plasma physics phenomena.     

Anisotropy of the electron-phonon scattering rate in metals

A method of measuring the temperature dependent part of the electron scattering ratev(T) for separate groups of electrons has been developed on the basis of the radio-frequency size effect. The temperature dependence of the amplitude of a radio-frequency size effect line yields information on the probability of electron scattering averaged over the vicinity of the corresponding extremal cross section of the Fermi surface (FS). This method was applied to two problems:

1. the determination of the electron-phonon scattering rate on the FS point-by-point in noble metals; and
2. the extraction of the contribution of electron-phonon scattering collisions with electron transfering from one sheet of the FS to another to the total electron-phonon scattering rate.

     

Detection of highly ionizing particles: Nonlinear near-surface phenomena in silicon radiation detectors

As far as the detection system is concerned, experimens on synthesis and study of the properties of superheavy nuclei is one of the most difficult tasks. In fact, these experiments can be considered extreme in many senses:

• —extremely low (fractions of a picobarn-picobarns) formation cross sections of the products under investigation
• —extremely high heavy ion beam intensities for example, ～1.1–1.5 pμA^{1 48}Ca
• —high radioactivity of actinide targets, which are used in the experiments aimed at the synthesis of super-heavy nuclei
• —very long duration of the experiment (as long as a year)
• —extremely low yield of the products under investigation (sometimes less than 1 per month)
• —very high sensitivity of the detection system
• —radical suppression of the background products (method of “active correlations”).

The two last points are the subject of the present paper, as well as the subject of two of my reviews published before. It is evident that without knowledge of the nature of the internal processes in semiconductor detectors it is virtually impossible to provide clear detection of ultra rare signals. In the present paper, the author reports on the investigation of near-surface phenomena in silicon radiation detectors, first of all bearing in mind the theoretical-methodological aspect of these phenomena. Non-equilibrium electron-hole recombination, pulse height defect formation, charge multiplication, and formation of “hot” electron system, are considered. With just these phenomena one can observe nonlinearity of energy-charge-amplitude conversion for heavy ion (recoil nucleus) registered by a silicon detector. Practical applications are also considered. One of them is a deeply modified method of “active correlations”. Projection of applying the method in the experiments with the modernized cyclotron (DC-280 FLNR project) is projected as well as possible applications in the heavy-ion-induced complete fusion nuclear reactions.     

Small-angle X-ray scattering on spinodal,nucleotic or coarsening processes in two-phase systems containing spherical,fibrillar or lamellar inhomogeneities

We study the effects of some of the most important and typical structural changes in two-phase systems on selected structural parameters obtained from small-angle x-ray scattering (SAXS) measurements. To limit the present study, it was assumed that the Phase, 1, embedded in the matrix

1. is monodispersed and homogeneous,
2. possesses one of the three most extreme shapes (spherical, fibrillar or lamellar) and
3. changes its behaviour

1. through type change (spinodal or nucleotic or coarsening), without changing the shape,
2. through a change of the shape only, or
3. through a) (type change) and b) (shape change) simultaneously.

To find the type of change for three basically different shapes of Phase 1 and to calculate its intensity (amount of the change) the following three SAXS parameters must be compared before and after the treatment of the system:

1. chord lengthl ₁ (and/or radius of gyrationR),
2. volume partw ₁ of the Phase 1, and
3. relative inner surfaceS _v of the system.

It is shown by this comparison that by the pure type change in the case of

1. spinodal change, all three SAXRS parameters are increasing or decreasing simultaneously and proportional to a power of the intensity of the change,
2. nucleotic change,l ₁ (and/orR) is unchanged, the other two (w ₁ andS _v ) are increasing or decreasing simultaneously and directly proportional to the intensity,
3. coarsening change,w ₁ is unchanged and anincreasing ofl ₁ is always accompanied by adecreasing ofS _v and vice versa.

In addition to this type change, the cases of mere changes of the shape (“shape change”) and finally of simultaneous type and/or shape change are studied. For the case of pure shape change the alteration of the dimensions (chord lengthl ₁ and/or radius of gyrationR) must be followed. The limitations of the analyses of the simultaneous type and/or shape change are discussed in detail.