a Volume in the Comprehensive Dictionary of PHYSICS DICTIONARY OF Material Science and High energy physics © 2001 by CRC Press LLC Comprehensive Dictionary of Physics Dipak Basu Editor-in-Chief Forthcoming and PUBLISHED VOLUMES Dictionary of Pure and Applied Physics Dipak Basu Dictionary of Material Science and High Energy Physics Dipak Basu Dictionary of Geophysics, Astrophysics, and Astronomy Richard A. Matzner © 2001 by CRC Press LLC a Volume in the Comprehensive Dictionary of PHYSICS Edited by Dipak Basu DICTIONARY OF Material Science and High energy physics Boca Raton London New York Washington, D.C. CRC Press © 2001 by CRC Press LLC This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. 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Visit the CRC Press Web site at www.crcpress.com © 2001 by CRC Press LLC No claim to original U.S. Government works International Standard Book Number 0-8493-2889-6 Library of Congress Card Number 00-051950 Printed in the United States of America 2 3 4 5 6 7 8 9 0 Printed on acid-free paper Library of Congress Cataloging-in-Publication Data Dictionary of Material Science and High Energy Physics / edited by Dipak Basu. p. cm. ISBN 0-8493-2889-6 (alk. paper) 1. Particles (Nuclear Physics)—Dictionaries. 2. Quantum theory—Dictionaries. 3. Materials—Dictionaries. I. Basu, Dipak. II. Series. QC772 .D57 2001 539 ′ .3—dc21 00-051950 2891 disclaimer Page 1 Friday, April 6, 2001 3:46 PM Preface The Dictionary of Material Science and High Energy Physics (DMSHEP) is one of the three major volumes being published by CRC Press, the other two being Dictionary of Pure and Applied Physics and Dictionary ofGeophysics, Astrophysics,andAstronomy. Each of these three dictionaries is entirely self-contained. The aim of the DMSHEP is to provide students, researchers, academics, and professionals in general with definitions in a very clear and concise form. A maximum amount of information is available in this volume that is still of reasonable size. The presentation is such that readers will not have any difficulty finding any term they are looking for. Each definition is given in detail and is as informative as possible, supported by suitable equations, formulae, and diagrams whenever necessary. ThefieldscoveredintheDMSHEParecondensedmatter,fluiddynamics, materialscience,nuclear physics, quantum mechanics, quantum optics, plasma physics, and thermodynamics. Terms have been chosen from textbooks, professional books, scientific and technical journals, etc. The authors are scientists at research institutes and university professors from around the world. Like most other branches of science, the field of physics has grown rapidly over the last decade. As such, many of the terms used in older books have become rather obsolete. On the other hand, new terms have appeared in scientific and technical literature. Care has been taken to ensure that old terms are not included in the DMSHEP, and new terminologies are not missed. Some of the terms are related to other fields, e.g., engineering (mostly electrical and mechanical), mathematics, chemistry, and biology. Readership includes physicists and engineers in most fields, teachers and students in physics and engineering at university, college, and high school levels, technical writers, and, in general, professional people. The uniqueness of the DMSHEP lies in the fact that it is an extremely useful source of infor- mation in the form of meanings of scientific terms presented in a very clear language and written by authoritative persons in the fields. It would be of great aid to students in understanding text- books, help academics and researchers fully appreciate research papers in professional scientific journals, provide authors in the field with assistance in clarifying their writings, and, in general, benefit enhancement of literacy in physics by presenting scientists and engineers with meaningful and workable definitions. Dipak Basu © 2001 by CRC Press LLC CONTRIBUTORS Ibrahim H. Adawi University of Missouri-Rolla Rolla, Missouri Kazuhiro Akimoto Teikyo University Utsunomiya, Japan Cetin Aktik University of Sherbrooke Sherbrooke, Quebec, Canada Mooread Alexanian University of North Carolina Wilmington, North Carolina Roger Andrews University of West Indies St. Augustine, Trinidad Supriyo Bandyopadhyay University of Nebraska Lincoln, Nebraska Rama Bansil Boston University Boston, Massachusetts Dipak Basu Carleton University Ottawa, Canada Glenn Bateman Lehigh University Bethlehem, Pennsylvania Subir K. Bose University of Central Florida Orlando, Florida Daniel R. Claes University of Nebraska Lincoln, Nebraska Don Correll Lawrence Livermore National Laboratory Livermore, California Paul Christopher Dastoor University of Newcastle Callaghan, NSW, Australia Anupam Garg Northwestern University Evanston, Illinois Willi Graupner Virginia Tech Blacksburg, Virginia Muhammad R. Hajj Virginia Tech Blacksburg, Virginia Parameswar Hari California State University Fresno, California Robert F. Heeter Lawrence Livermore National Laboratory Livermore, California Ed V. Hungerford University of Houston Houston, Texas Nenad Ilic University of Manitoba Winnipeg, Canada Takeo Izuyama Toho University Miyama, Japan Jamey Jacob University of Kentucky Lexington, Kentucky Yingmei Liu University of Pittsburgh Pittsburgh, Pennsylvania Vassili Papavassiliou New Mexico State University Las Cruces, New Mexico © 2001 by CRC Press LLC Perry Rice Miami University Oxford, Ohio Francesca Sammarruca University of Idaho Moscow, Idaho Douglas Singleton California State University-Fresno Fresno, California Reeta Vyas University of Arkansas Fayetteville, Arkansas Thomas Walther Texas A&M University College Station, Texas Peter Winkler University of Nevada Reno, Nevada Bernard Zygelman University of Nevada Las Vegas, Nevada © 2001 by CRC Press LLC Editorial Advisor Stan Gibilisco © 2001 by CRC Press LLC A Abelian group Property of a group of el- ements associated with a binary operation. In an Abelian group, the group elements commute under the binary operation. If a and b are any two group elements and if the (+) sign denotes the binary operation, then, for an Abelian group, a +b = b + a. absolute plasma instabilities A class of plasma instabilities with amplitudes growing with time at a fixed point in the plasma medium. Compare with convective instabilities. absolute temperature (T ) Scale of temper- ature defined by the relationship 1/T = (∂S/ ∂U) V,N ; S denotes entropy, U the internal en- ergy, and V the volume of an isolated system of N particles. The absolute temperature scale is same as the Kelvin scale of temperature if S = k B ln , where  is the number of mi- crostates of the system and k B is the Boltzmann constant. absolute viscosity Measure of a fluid’s resis- tance to motion whose constant is given by the relation between the shearstress, τ, and velocity gradient, du/dy, of a flow such that τ ∝ du dy . The constant of proportionality is the absolute viscosity. For Newtonian fluids, the relation is linear and takes the form τ = µ du dy where µ, also known as dynamic viscosity, is a strong function of the temperature of the fluid. For gases, µ increases with increasing temper- ature; for liquids, µ decreases with increasing temperature. For non-Newtonian fluids, the re- lationisnot linearandapparentviscosityis used. absolute zero (0K) The lowest temperature on the Kelvin or absolute scale. absorption A process in which a gas is con- sumed by a liquid or solid, or in which a liquid is taken in by a solid. In absorption, the substance absorbed goes into the bulk of the material. The absorption ofgasesin solidsissometimescalled sorption. absorption band (F) If alkali halides are heated in the alkali vapor and cooled to room temperature, there will be a Farbe center defect. F-center is a halide vacancy with its bound elec- tron. Theexcitationfromgroundstateto thefirst excited state in F-center leads to an observable absorption band, which is called F-absorption band. Because there is an uncoupled electron in F-center, it has paramagnetism. absorption band (V) If alkali halides are heated in the halide vapor and cooled to room temperature, there willbe a V-center defect in it. V-center isanalkali vacancywithits boundhole. The excitation from ground state to the first ex- cited state in V-center causes a V-absorption band, which lies in theedgeofultra-visionlight. absorption coefficient A measure of the probability that an atom will undergo a state- transition in the presence of electromagnetic ra- diation. In modern atomic theory, an atom can make a transition to a quantum state of higher energy by absorbing quanta of photons. The en- ergy defect of the transition is matched by the energy posited in the photons. absorption of photons The loss of light as it passes through material, due to its conversion to other energy forms (typically heat). Light incident on an atom can induce an upward tran- sition of the atom’s state from an energy ε 0 to an energy ε n = ε 0 + ¯ hω = ε 0 + ¯ hck, where ω = (ε n − ε 0 )/ ¯ h is the angular frequency of the light, and k = 2π/λ its propagation num- ber. This is interpreted as the absorption of an individualphotonofenergy ¯ hω = ε n −ε 0 by the positive frequency component e −iωt of a pertur- bation intheHamiltonianof the atomicelectron. The absorption cross section depends on the di- rection and polarization of the radiation, and is © 2001 by CRC Press LLC given by σ abs (ω) = 4π 2 e 2 ωc  n         n        ρ j ρ −k · ρ λ        0         2 δ ( ε n ε 0 − ηω ) for a polarization vector ρ λ , wave vector ρ k = (2π/λ) ρ p and probability current density ρ j ( ρ r ,t), and ε 0 ,ε n are the energy of the initial |0 > and final |n>atomic states. absorption of plasma wave energy Theloss of plasma wave energy to the plasma particle medium. For instance, an electromagnetic wave propagating through a plasma medium will in- crease the motion of electrons due to electro- magnetic forces. As the electrons make col- lisions with other particles, net energy will be absorbed from the wave. acceptor A material such as silicon that has a resistivity halfway between an insulator and a conductor (on a logarithmic scale). In a pure semiconductor, the concentrations of negative charge carriers (electrons) and positive carriers (holes) are the same. The conductivity of a semiconductor can be considerably altered by adding small amounts of impurities. The pro- cess of adding impurity to control the conduc- tivity is called doping. Addition of phospho- rus increases the number of electrons available for conduction, and the material is called n-type semiconductor (i.e., the charge carriers are neg- ative). The impurity, or dopant, is called a donor impurity in this case. Addition of boron results in the removal of electrons. The impurity in this case is called the acceptor because the atoms added to the material accept electrons, leaving behind positive holes. acceptor levels The levels corresponding to acceptors are called acceptor levels. They are in the gap and very close to the top of the valence band. accidental degeneracy Describes a property of a many-particle quantum system. In a quan- tum system of identical particles, the Hamilto- nian is invariant under the interchange of coor- dinates of a particle pair. Eigenstates of such a systemaredegenerate,andthispropertyiscalled exchange symmetry. If a degeneracy exists that is not due to exchange symmetry, it is called accidental degeneracy. acoustic modes The relation between fre- quency w and wave vector k is called the dis- persion relation. In the phonon dispersion rela- tion, there are optical and acoustical branches. Acoustical branches describe the relative mo- tion among primitive cells in crystal. If there are p atoms in each primitive cell, the number of acoustical modes is equal to the degree of freedom of each atom. For example, in three- dimensional space, the number of acoustical modes is three. acoustics The study of infinitesimal pressure waves that travel at the speed of sound. Acous- tics is characterized by the analysis of linear gas dynamic equations where wave motion is small enoughnottocreatefiniteamplitudewaves. The fluid velocity is assumed to be zero. acoustic wave See sound wave. action A property of classical and quan- tum dynamical systems. In Hamilton’s for- mulation of classical dynamics, the quantity S =  t 2 t 1 dtL(q(t), ˙q(t)), where L(q(t), ˙q(t)) is the Lagrangian, and q(t), ˙q(t) is the dynami- cal variable and its time derivative, respectively, is called the action of the motion. In quantum physics, Planck’s constant h has the dimensions of an action integral. If the action for a classical system assumes avaluethatiscomparable to the value of Planck’s constant, the system exhibits quantum behavior. Feynman’s formulation of quantum mechanics involves a sum of a func- tion of the action over all histories. activity (λ) The absolute activity is defined as λ = exp(µ/k B T), where µ is the chemical potential at temperature T , and k B is the Boltz- mann constant. added mass Refers to the effect of increased drag force on a linearly accelerating body. For © 2001 by CRC Press LLC [...]... array of positive ions As a result, there are bands of energy, of allowed energy levels instead of single discrete energy levels, where an electron can exist The allowed bands are separated by gaps of forbidden energy called forbidden gaps The valence electrons in a solid are located in an energy band called the valence band The energy band in which electrons can freely move is called the conduction band... direction of © 20 01 by CRC Press LLC annealing The process of heating a material to a temperature below the melting point, and then cooling it slowly annihilation The result of matter and antimatter (for example an electron and a positron, particles of identical mass but opposite charge) undergoing collision The resulting destruction of matter gives off energy in the form of radiation Conservation of energy. .. 20 01 by CRC Press LLC band gap The results of band calculation show that electrons in crystal are arranged in energy bands Because of some perturbations which come from long range or short range interaction in the crystal, there are some forbidden regions in these bands which are called band gaps or energy band gaps band theory An electron in a crystalline solid can exist only in certain values of energy. .. and energy gaps in metals can be derived from the BCS wave function beam A concentrated, ideally unidirectional stream of particles characterized by its flux (number per unit area per unit time) and energy In high energy experiments, typically a few MeV to T eV in energy with intensities as high as 10 33 /cm2 /sec directed at targets of only a few mm2 in area for the purposes of studying collisions and. .. relation 1/ λ = RH (1/ n2 − 1/ 4), RH = 1. 07 × 10 7 m 1 is the Rydberg constant, and n is an integer whose value is greater than 2 This is called the Balmer formula and, as an empirical relation, pre-dates the Bohr derivation by a couple of decades banana orbit In a toroidal geometry, the fast spiraling of a charged particle around a magnetic field line is accompanied by a slow drift motion of the particle’s... Reynolds and Mach numbers) are the primary factors in the creation of lift and drag (see hydrofoil) alcator plasma machine Name given to a set of tokamaks designed and built at MIT; these particles have a typical energy range of 4-8 MeV and are easily dissipated within a few centimeters of air (or less than 0.005mm of aluminum) ambipolar plasma diffusion Diffusion process in which a buildup of spatial... measurement of velocity in any gas (anemometry, e.g., hot-wire anemometry) angstrom (Å) Unit of length equal to one trillionth of a meter (10 10 m or 1/ 10th of a nanometer) An angstrom is not an SI unit angular momentum A property of any revolving or rotating particle or system of particles Classically, a particle of mass m moving with velocity v at a distance r from a point O carries a momentum relative... observable particle mass (sometimes called the renormalized mass) The self -energy (interaction energy, for example, between an electron and its own electromagnetic field which is visualized as the continuous emission by the electron of virtual photons that are subsequently reabsorbed) becomes an inseparable part of a particle’s observed rest mass barn A unit of area typically used in nuclear and high energy physics. .. numbers j1 and j2 ), can combine to yield any quantized state with a total angular momentum quantum number in the range |j1 − j2 | ≤ j ≤ (j1 + j2 ) but with the Jz projections simply adding as m = m1 + m2 The addition rules follow from the nature of the angular momentum operator relations addition theorem The identity, Pl [cos(ˆ 1 · r m=l 4π ∗ ˆ r2 )] = 2l +1 m=−l Ylm ( 1 1 )Ylm (θ2 φ2 ), where 1 1 and. .. other particles, such as those measuring the gyro-magnetic ratio The anomalous magnetic moment is expressed in terms of the departure of a constant g from its expected bare electron value of two: g = 2 [1 + (e2 /4π h )1/ 2π + · · · ] and can be accounted for ¯ by a phenomenological term in the interaction astrophysical plasmas Includes the sun and stars, the solar wind and stellar winds, large parts of the . PUBLISHED VOLUMES Dictionary of Pure and Applied Physics Dipak Basu Dictionary of Material Science and High Energy Physics Dipak Basu Dictionary of Geophysics, Astrophysics, and Astronomy Richard. the Comprehensive Dictionary of PHYSICS DICTIONARY OF Material Science and High energy physics © 20 01 by CRC Press LLC Comprehensive Dictionary of Physics Dipak Basu Editor-in-Chief Forthcoming and PUBLISHED. and High Energy Physics (DMSHEP) is one of the three major volumes being published by CRC Press, the other two being Dictionary of Pure and Applied Physics and Dictionary ofGeophysics, Astrophysics,andAstronomy.