bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radio frequency cavities
Authors: Wilson E. J. N. 
Published: January 2010

Abstract
A time varying field is essential for acceleration. After commenting that neither waves in free space nor in a waveguide can be matched to the velocity of a particle, this chapter shows how a chain of pill box cavities or a corrugated tube can propagate a wave whose phase velocity is less than c. The importance of the transit-time factor is mentioned. Maxwell's equations apply to such resonators. Particular boundary conditions apply at the conducting walls. The mode, the quality factor, and the shunt impedance are calculated for simple cavity. The dispersion diagram of an iris-loaded cavity is discussed, as are the choice of modes and the difference between standing wave and travelling wave configurations. The klystron, used to power the cavities, is discussed together with the various modes of coupling.
Essential Density Functional Theory
Authors: Finnis Mike 
Published: January 2010

AbstractStarting with an explanation of what functionals and functional derivatives are, this chapter develops the basic functional calculus needed to understand density functional theory (DFT). DFT for electrons in condensed matter is then explained, starting with the Thomas–Fermi model in which the kinetic energy is a local functional of the density. The Hohenberg–Kohn–Sham DFT is then developed, leading to the Schr ö dinger–like Kohn–Sham equations. The local density approximation (LDA) for exchange and correlation is explained. The chapter includes an introduction to the self-consistent solution of the Kohn–Sham equations.
Linear Response Theory
Authors: Finnis Mike 
Published: January 2010

AbstractThis chapter introduces the concept of linear response theory. The response function giving the change in charge density induced by a small change in the potential is derived in terms of the Green function of Chapter 1. These concepts lead to an expression for the error in the Harris–Foulkes functional due to neglect of complete self-consistency, which is shown to be second order in the error in the model input charge density. Linear response in jellium — the uniform gas of electrons — is explored in detail, including the response to non-local potentials. This is background for deriving pairwise potentials in simple metals in Chapter 6. The incorporation of exchange and correlation in the response function is described, whereby pairwise potential models in simple metals can contain more physics than the local density approximation or generalized gradient approximations used in fully self-consistent density functional theory.
Pairwise potentials in simple metals
Authors: Finnis Mike 
Published: January 2010

Abstract
This chapter shows how pairwise potentials for simple, s-p bonded metals, can be derived from first-principles. The starting point is jellium, and the ions are specified as pseudopotentials, local or non-local. The application of perturbation theory to second order in the pseudopotentials leads to the energy in the form of a density dependent, structure independent term plus a sum of density dependent, pairwise interactions between the ions. With the help of the Hellmann–Feynman theorem a simple physical interpretation is given in terms of interacting, spherically-symmetric pseudoatpms. A simple example using the Ashcroft empty core pseudopotential and the Thomas–Fermi approximation is worked through to illustrate the concepts. The use of a local density as a parameter within the pair potential is discussed.
Ionic Models
Authors: Finnis Mike 
Published: January 2010

AbstractThis chapter presents models for interatomic potentials in ionic materials. As for the other models described in this book, the derivations are based on density functional theory and the variational principle, which leads to all the commonly used types of model. The simplest model of all is the rigid ion model, or Born model. It is introduced here by changing the charges on the nuclei in a rare gas solid and applying first-order perturbation theory. To go beyond the rigid ion model the second-order functional derived previously is invoked. This leads to a class of models with deformable ions, the simplest example of which has the same structure as the classical shell model. Compressible ion and variable charge transfer models are discussed. Classical charge transfer models are seen as equivalent to self-consistent tight-binding model in which the effect of covalency is neglected.
7 Experimental techniques
Authors: Hempelmann Rolf 
Published: January 2010

Abstract
This chapter describes the practical aspects of quasielastic neutron scattering experiments and the necessary processing of raw data, including tips and tricks. The sample thickness has to be chosen as a compromise between sufficiently high scattering intensity and sufficiently low multiple scattering. For the background subtraction, self-shielding has to be taken into account, and then resolution corrections have to be performed. For complex situations with the superposition of several scattering components, a simultaneous fit enables the extraction of desired information from the data. Another problem is multiple scattering; corresponding correction strategies are outlined. Finally, the two spectrometer types most commonly used for quaisielastic neutron scattering experiments — time-of-flight instruments and backscattering instruments — are described in some detail. As a related method, quasielastic Mössbauer spectroscopy is briefly mentioned.
9 Metals and alloys
Authors: Hempelmann Rolf 
Published: January 2010

Abstract
For the fcc noble metals and for bcc metals of group V and VI such as Mo, W, V, and Nb, atomic diffusion is slow compared to the case of bcc alkali metals Li, Na, or K. The group IV metals Ti, Zr, and Hf have still higher diffusivities. The first section of the chapter describes the investigation of sodium diffusion, in particular presenting the encounter model of vacancy diffusion in detail. The second part deals with similar experiments on bcc-β-titanium, where the relation between high diffusivity and soft modes as measured by triple axis spectrometry is explained. QENS diffusion studies are also performed for some alloys and intermetallic compounds.
Fabrication techniques and methods for semiconductor quantum dots
Authors: Ustinov Victor M. , Zhukov Alexey E. , Egorov Anton Yu. , Maleev Nikolai A. 
Published: January 2010

AbstractThis chapter first considers the basic principles of molecular beam epitaxy (MBE) of III-V materials. It describes a typical MBE system and its components with special attention to the reflection high-energy electron diffraction system for in-situ monitoring of a growth surface. Metal organic chemical vapour deposition (MOCVD), chemical reactions in MOCVD process and typical reactor scheme are then described. The chapter also describes different methods of in situ formation of one- or zero-dimensional quantum size objects, including formation of quantum wires on a V-grooved substrate, quantum wires and dots on high-index surfaces, and selective epitaxial growth of low-dimensional structures. Special attention is paid to a method of quantum dot formation in Stranski–Krastanow growth mode.
Power characteristics of quantum dot lasers
Authors: Ustinov Victor M. , Zhukov Alexey E. , Egorov Anton Yu. , Maleev Nikolai A. 
Published: January 2010

AbstractThis chapter considers the quantum dot active region as a possible candidate for high-power laser applications. Thermal rollover, catastrophic optical mirror damage, and other mechanisms of power limitation in diode lasers are discussed, taking into account specific aspects of quantum dot lasers. Power conversion efficiency in a QD laser is analytically treated, and influence of laser structure and QD parameters is also discussed. Internal loss and other parameters affecting slope efficiency of a QD laser are considered in connection with inherent properties of self-organized quantum dots. The chapter also addresses issues associated with the realization of a continuous-wave lasing regime in QD lasers. Device characteristics are summarized for state-of-the-art high-power quantum dot lasers operating in the 0.9-1.1 and 1.2-1.3 spectral ranges.
Conclusions
Authors: Ustinov Victor M. , Zhukov Alexey E. , Egorov Anton Yu. , Maleev Nikolai A. 
Published: January 2010

AbstractThis chapter presents some concluding remarks. Remarkable progress in the development of self-organized quantum dot lasers is pointed out and the most notable results, e.g. a record-low threshold current density, are briefly summarized. The main parameters of QD arrays affecting the laser’s threshold characteristics are emphasized. It is recognized that device performance of existing QD lasers is still inferior when compared with the theoretical predictions for the ideal quantum dots. Inhomogeneous broadening associated with the size non-uniformity of the islands is the main problem that still remains. An expectation of bright prospects is expressed for device application of quantum dots emitting in wavelength ranges beyond the spectral limit of a quantum well.
Dynamical Theory of X-Ray Diffraction
Authors: Authier André 
Published: January 2010

Abstract
X-ray diffraction is a major tool for the study of crystal structures and the characterization of crystal perfection. Since the discovery of X-ray diffraction by von Laue, Friedrich, and Knipping in 1912 two basic theories have been used to describe this diffraction. One is the approximate geometrical, or kinematical theory, applicable to small or highly imperfect crystals; it is used for the determination of crystal structures and the study of powders and polycrystalline materials. The other one is the rigorous dynamical theory, applicable to perfect or nearly perfect crystals and, for that reason, is the one used for the assessment of the structural properties of high technology materials. It has witnessed exciting developments since the advent of synchrotron radiation. This book provides an account of the dynamical theory of diffraction and of its applications. The first part serves as an introduction to the subject, presenting early developments, Ewald's theory of dispersion and the basic results of Laue's dynamical theory. This is followed in the second part by a detailed development of the diffraction and propagation properties of X-rays in perfect crystals, including the study of anomalous absorption, Pendellösung, grazing incidence diffraction (GID) and n-beam or multiple-beam diffraction. The third part constitutes an extension of the theory to the case of slightly and highly deformed crystals. The last part gives three applications of the theory: X-ray optics for synchrotron radiation, location of atoms at surfaces and interfaces and X-ray diffraction topography.
3 Geometrical theory of X-ray diffraction
Authors: AUTHIER ANDRÉ 
Published: January 2010

Abstract
This chapter describes a concise summary of the geometrical theory of X-ray diffraction, which is not the main topic of the book. The amplitude diffracted by a periodic electron distribution is calculated and the structure factor is introduced. The intensity diffracted by a small crystal is then calculated and the expression of the angular variations of the reflectivity discussed. Finally, the integrated intensity is calculated both in the reflection and the transmission geometries and the mosaic crystal model introduced.
Elementary dynamical theory
Authors: AUTHIER ANDRÉ 
Published: January 2010

Abstract
This chapter presents the basic properties of dynamical diffraction in an elementary way. The relationship with the band theory of solids is explained. The fundamental equations of dynamical theory are given for scalar waves as a simplification; the solutions of the propagation equation are then derived for an incident plane wave in the 2-beam case; and the amplitude ratio between reflected and refracted waves deduced. The notions of wavefields, dispersion surface, and tie points are introduced. Two experimental set-ups are considered: transmission and reflection geometries. The boundary conditions at the entrance surface of the crystal are expressed in each case and the intensities of the refracted and reflected waves calculated as well as the anomalous absorption coefficient, due to the Borrmann effect, the Pendellösung interference fringe pattern and the integrated intensity. It is shown that the geometrical diffraction constitutes a limit of dynamical diffraction by small crystals. At the end of the chapter dynamic diffraction by quasicrystals is considered.
5 Properties of wavefields
Authors: AUTHIER ANDRÉ 
Published: January 2010

Abstract
This chapter is the first of the next few chapters devoted to plane-wave advanced dynamical theory. The fundamental equations of dynamical diffraction are derived for vector waves and the expression of the dispersion equation is given in the two-beam case and for absorbing crystals, the following discussion being limited to geometrical situations where neither the incidence nor the emergence angle is grazing. The notion of wavefields and the dispersion surface are introduced, and it is shown that the Poynting vector, which gives the direction of propagation of the energy, is normal to it. The boundary conditions at the entrance surface are then introduced. Transmission and reflection geometries are treated separately. For each case, the deviation parameter is introduced geometrically and the coordinates of the tiepoints determined, the Pendellösung distance (extinction distance in the reflection geometry), Darwin width, the anomalous absorption coefficient, index of refraction, the phase and amplitude ratios of the reflected and refracted waves are calculated. Borrmann's standing wave interpretation of the anomalous absorption effect is given. The last section is to the case where Bragg's angle is close to π/2.
13 Ray tracing in slightly deformed crystals
Authors: AUTHIER ANDRÉ 
Published: January 2010

Abstract
This chapter is devoted to the propagation of X-ray wavefields in slightly deformed crystals where the deformation is small enough for the notions of dispersion surface and wavefields to be locally valid. A local reciprocal-lattice vector and local effective misorientation are defined. The trajectories of the wavefields (ray tracing) are determined using the Eikonal approximation. The case of a constant strain gradient is considered in detail and it is shown that the ray trajectories are bent, giving rise to the mirage effect; both the transmission and reflection geometries are considered. The diffracted intensities are calculated for an incident plane wave and an incident spherical wave. Shape of the Pendellösung fringes in a deformed crystal is discussed.
16 Location of atoms at surfaces and interfaces using X-ray standing waves
Authors: AUTHIER ANDRÉ 
Published: January 2010

Abstract
This chapter describes the use of dynamical diffraction for the location of atoms and impurities at surfaces and interfaces using the standing waves formed by the superposition of the incident and reflected waves. After an introduction giving the principle of the method and its historical development, the variations of the intensity of the wavefield in the reflection, or Bragg, geometry are calculated and the fluorescent yield determined. Applications to the determination of surface structures, nature and position of impurities, polarity of heteropolar crystals are described. The case of deformed crystals is also considered. The last section concerns standing waves associated with specular reflection.
Better accuracy from simple pendulums
Authors: Matthys Robert James 
Published: January 2010

Abstract
This chapter deals with simple pendulums and with several things that can be done to improve their accuracy. Most of the items have only a minor effect on accuracy, but they add up. The pendulum should be enclosed in a case to protect it from the air currents of an open room, which will push the pendulum around and give erratic timing. A metal pendulum rod is recommended over a wooden one. If the pendulum is not temperature compensated, a low thermal expansion metal like iron must be chosen for the pendulum rod. If the pendulum is not temperature compensated, the bob must be supported at its bottom edge rather than at its middle or top edge. Other tips: use a low drag bob shape, walls dose to the pendulum cause a problem with relative humidity; slide the top end of the suspension spring up and down through a narrow slot; keep the number of piece parts and mechanical joints in a pendulum to a minimum.
Does a pendulum’s axis of rotation shift with amplitude?
Authors: Matthys Robert James 
Published: January 2010

Abstract
This chapter describes an experiment to determine whether a pendulum's axis of rotation moves when the swing amplitude is increased. This issue presupposes that the pendulum has a flat spring type of suspension. A flat suspension spring bends all along a section of its length, so there is no obvious reason to indicate that a pendulum's axis of rotation would remain fixed when the swing amplitude is increased. The axis of rotation is found by measuring the horizontal travel of two points on the pendulum rod, one point a little above the axis of rotation and the other a little below it. The axis of rotation does move downward slightly (down the suspension spring), as the pendulum's swing amplitude increases. This should make the pendulum speed up as the amplitude increases, but in reality a pendulum actually slows down with increasing amplitude.
Putting Q in perspective
Authors: Matthys Robert James 
Published: January 2010

Abstract
Q is a clock oscillator's quality factor, a measure of how low its energy losses are with respect to the total energy stored in the motion of the oscillator. This chapter provides some new information on Q and looks at arguments both for and against it. The value of Q rests on two facts: that increasing a pendulum's Q means lower drive forces, which means less pendulum disturbance, which means a more accurate clock; and that historically (but not scientifically), a higher Q generally means a higher long-term accuracy. On a global scale of wristwatches to atomic frequency standards, Q is historically often proportional to long-term clock accuracy. This makes Q significant as an indicator of clock accuracy on a global clock scale. On the more limited scale of pendulum clocks by themselves, both temperature compensation and aging are more important issues than Q since their errors are bigger than the increased accuracy available from an increased Q.
Barometric compensation with a crossed spring suspension?
Authors: Matthys Robert James 
Published: January 2010

Abstract
A crossed spring suspension provides an axis of rotation characterised by extremely low friction, something that a pendulum can use. The suspension typically consists of four flat strips of spring metal (two sets of two, with the two sets oriented at 90 degrees to each other) that are clamped at the ends. For small rotation angles, the axis of rotation is nominally located at the springs' crossover point in the middle of the springs. The suspension has three important characteristics. First, it has extremely low friction. Second, the rotational stiffness of the suspension springs (in units of torque per unit angle about the axis of rotation) varies with the total weight suspended from the springs, that is, with the weight of the pendulum. Third, the axis of rotation moves horizontally as the pendulum swings away from its vertical orientation in the center of swing. This chapter proposes an idea for barometric compensation of a pendulum using a crossed spring suspension.
Stability of suspension spring materials
Authors: Matthys Robert James 
Published: January 2010

Abstract
A pendulum's suspension spring is so simple physically, and yet so complicated in questions of size, what material to use, bending fatigue, length stability, the effects of its Young's modulus varying with temperature, how to solidly grab hold of its top and bottom ends, whether to use one spring or two, etc. This chapter deals with the first four questions. The suspension spring's length, thickness, and material are varied to determine how these parameters affect the pendulum's timing and thermal hysteresis. The goal is to improve the timing and reduce the thermal hysteresis. This chapter covers what actually happens in practice to a pendulum when the suspension spring's length, thickness, and material are changed. Experimental results show that type 642 aluminum silicon bronze, hard temper, is the best material for a pendulum's suspension spring.
Electronic correction for air pressure variations
Authors: Matthys Robert James 
Published: January 2010

Abstract
At atmospheric pressure, a pendulum is slightly buoyant to a ‘sea’ of air. This buoyancy causes the pendulum's timing to be a little sensitive to the air's density, and consequently to its pressure. Timing error can be corrected mechanically by putting a small bellows-supported weight on the pendulum. As the air pressure increases, the bellows shrinks and lowers the weight resting on top of it, speeding up the pendulum to compensate for its natural slowdown with increasing pressure. This assumes that the bellows' weight is located in the pendulum's upper half. If located in the lower half, the bellows-supported weight must hang below the bellows instead of sitting on top of it. The effect of the air pressure variations can also be corrected for electronically, using a silicon-based pressure sensor, some electronic circuitry, and an electromagnetic (coil and magnet) pendulum drive. This chapter describes an electronic circuit that corrects for a pendulum's air pressure variations.
Kinetic Coefficients for Granular Gases of Viscoelastic Particles
Authors: Brilliantov Nikolai V. , Pöschel Thorsten 
Published: January 2010

Abstract
This chapter analyzes the kinetic coefficients for granular gases of viscoleastic particles. The kinetic coefficients reveal a much more complicated time and temperature dependence than for the case of ε = const. For such gases, the transport coefficients and cooling rates have different temperature dependencies.
Structure Formation in Granular Gases of Viscoelastic Particles
Authors: Brilliantov Nikolai V. , Pöschel Thorsten 
Published: January 2010

Abstract
This chapter begins with a discussion of linearized equations for hydrodynamic modes. It then discusses stability analysis of the hydrodynamic modes and structure formation, and structure formation as a transient process. The stability analysis of hydrodynamic equations for a gas of viscoleastic particles shows that the conditions of instability for shear and heat modes depend on time. Thus, structure formation in granular gases is a transient process. Over time, the granular gas returns to the homogeneous cooling state.
Coherent Interactions
Authors: BARNETT STEPHEN M. , RADMORE PAUL M. 
Published: January 2010

AbstractThis chapter presents some of the models describing the time-dependent interaction between a simple atom and a field, which may be described either classically or fully quantum mechanically. A number of equivalent interaction pictures and the important rotating-wave approximation are introduced. The two-state dynamics of an atom coupled to a classical field is solved, starting with perturbation theory. Non-perturbative behaviour is analysed, leading to Rabi oscillations of the atomic probabilities. The Jaynes–Cummings model of the dynamics of a single two-state atom coupled to a single quantized mode of the electromagnetic field is solved leading to collapses and revivals of the excited state probability. An exactly soluble model of the coupling of a single state to a Bixon–Jortner quasi-continuum of discrete levels is analysed. Finally, the coherent interactions between two field modes, of the type common in nonlinear optics, are discussed.