scholarly journals One-particle reducible contribution to the one-loop scalar propagator in a constant field

2017 ◽  
Vol 923 ◽  
pp. 339-349 ◽  
Author(s):  
James P. Edwards ◽  
Christian Schubert
Keyword(s):  
Constant Field ◽  
The One

scholarly journals One-particle reducible contribution to the one-loop spinor propagator in a constant field

2017 ◽  
Vol 924 ◽  
pp. 377-386 ◽  
Author(s):  
N. Ahmadiniaz ◽  
F. Bastianelli ◽  
O. Corradini ◽  
J.P. Edwards ◽  
C. Schubert
Keyword(s):  
Constant Field ◽  
The One

New Method to Characterize Thin Oxide Reliability

1995 ◽  
Vol 386 ◽  
Author(s):  
Heng-Chih Lin ◽  
J. P. Snyder ◽  
C. R. Helms
Keyword(s):  
New Method ◽  
Constant Field ◽  
Testing Methods ◽  
Current Ramp ◽  
Linear Current ◽  
Oxide Reliability ◽  
Voltage Ramp ◽  
The One ◽  
Surface Microroughness ◽  
Linear Voltage

ABSTRACTNext generation ULSI devices will require ultra thin gate insulators where degradation due to contamination or surface microroughness is an even more important problem. Tunneling and breakdown characteristics are critical electrical testing methods, but unfortunately obtaining meaningful oxide integrity information on the one hand and tunneling IV's on the other is a tedious and time consuming process.In this research, we report on a new method to measure meaningful IV's, Qbd's, and Vbd's at the same time. This method uses a linear current ramp strategy where a voltage ramp to between 8–10 MV/cm is applied first followed by a linear current ramp until breakdown is reached. There are several advantages of this new method: The linear voltage ramp quickly and easily identifies low breakdown devices, whereas switching to a linear current ramp provides for nearly constant field stressing to obtain meaningful IV and Qbd

scholarly journals Asymptotic Behaviour of the QED Perturbation Series

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Idrish Huet ◽  
Michel Rausch de Traubenberg ◽  
Christian Schubert
Keyword(s):  
Asymptotic Behaviour ◽  
Structure Constant ◽  
Perturbation Series ◽  
Fine Structure Constant ◽  
Constant Field ◽  
Energy Limit ◽  
Loop Level ◽  
Large N ◽  
The One

I will summarize the present state of a long-term effort to obtain information on the large-order asymptotic behaviour of the QED perturbation series through the effective action. Starting with the constant-field case, I will discuss the Euler-Heisenberg Lagrangian in various dimensions and up to the three-loop level. This Lagrangian holds the information on the N-photon amplitudes in the low-energy limit, and combining it with Spinor helicity methods explicit all-N results can be obtained at the one-loop and, for the “all +” amplitudes, also at the two-loop level. For the imaginary part of the Euler-Heisenberg Lagrangian, an all-loop formula has been conjectured independently by Affleck, Alvarez, and Manton for Scalar QED and by Lebedev and Ritus for Spinor QED. This formula can be related through a Borel dispersion relation to the leading large-N behaviour of the N-photon amplitudes. It is analytic in the fine structure constant, which is puzzling and suggests a diagrammatic investigation of the large-N limit in perturbation theory. Preliminary results of such a study for the 1+1 dimensional case throw doubt on the validity of the conjecture.

A random-walk theory of tarnishing reactions

1967 ◽  
Vol 299 (1458) ◽  
pp. 354-370 ◽  
Keyword(s):  
Random Walk ◽  
Three Dimensional ◽  
Constant Field ◽  
Three Dimensional Model ◽  
Rate Laws ◽  
Positive Ions ◽  
Growth Laws ◽  
Constant Potential ◽  
Random Walk Theory ◽  
The One

Random-walk theory has been applied to describe the oxidation of metals. The one-dimensional random-walk problem with a growing site array has, in principle, been solved exactly provided the array is singly occupied and the hop probabilities are independent of site position. This result has been generalized to a pseudo three-dimensional model. The conditions for linear, parabolic and `logarithmic’ growth laws have been delineated. The case where the hop probabilities are different at a boundary has also been treated and it has been shown that, provided this difference is not too great, this leads to a different reaction rate but the same type of rate law. The effect of an electric field on the oxidation has been treated by considering the effect of the field on the hop probabilities, and rate laws for constant field and constant potential situations have been obtained. The way that the surface charge varies during the reaction by virtue of the net difference in rate of arrival of (say) electrons and positive ions at the oxide/ oxygen interface has been investigated numerically and it has been shown that there is often an appreciable region of approximately constant potential. The effect of multiple occupation of the random walk path has been qualitatively discussed.

scholarly journals Photon polarization tensor in circularly polarized Hermite- and Laguerre-Gaussian beams

2018 ◽  
Vol 33 (07n08) ◽  
pp. 1850044 ◽  
Author(s):  
Felix Karbstein ◽  
Elena A. Mosman
Keyword(s):  
Quantum Electrodynamics ◽  
Field Approximation ◽  
Constant Field ◽  
Polarization Tensor ◽  
Photon Polarization ◽  
Circularly Polarized ◽  
Polarized Beams ◽  
Effective Lagrangian ◽  
Linearly Polarized ◽  
The One

We derive analytical expressions for the photon polarization tensor in circularly polarized Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) beams, complementing the corresponding results for linearly polarized beams obtained recently. As they are based upon a locally constant field approximation of the one-loop Heisenberg–Euler effective Lagrangian for quantum electrodynamics (QED) in constant fields, our results are generically limited to slowly varying electromagnetic fields, varying on spatial (temporal) scales much larger than the Compton wavelength (time) of the electron.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

Fundamental Research into Thin Films in a Developing Country

1972 ◽  
Vol 30 ◽  
pp. 500-501
Author(s):  
J.A. Eades ◽  
E. Grünbaum
Keyword(s):  
Thin Films ◽  
Growth Process ◽  
Empirical Process ◽  
Nucleation And Growth ◽  
Research Groups ◽  
Film Research ◽  
Fundamental Research ◽  
Controlled Deposition ◽  
The One ◽  
The University

In the last decade and a half, thin film research, particularly research into problems associated with epitaxy, has developed from a simple empirical process of determining the conditions for epitaxy into a complex analytical and experimental study of the nucleation and growth process on the one hand and a technology of very great importance on the other. During this period the thin films group of the University of Chile has studied the epitaxy of metals on metal and insulating substrates. The development of the group, one of the first research groups in physics to be established in the country, has parallelled the increasing complexity of the field.The elaborate techniques and equipment now needed for research into thin films may be illustrated by considering the plant and facilities of this group as characteristic of a good system for the controlled deposition and study of thin films.

STM studies of crystal growth

1991 ◽  
Vol 49 ◽  
pp. 374-375
Author(s):  
M. G. Lagally
Keyword(s):  
Crystal Growth ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Sputter Deposition ◽  
Field Of View ◽  
Scanning Tunneling ◽  
Wide Field ◽  
Tunneling Microscopy ◽  
Wide Field Of View ◽  
The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

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