Dictionary of Material Science and High Energy Physics Part 1 pdf

Comprehensive Dictionaryof PHYSICS DICTIONARY OF Material Science and High energy physics... Comprehensive Dictionaryof Physics Dipak Basu Editor-in-Chief Forthcoming and PUBLISHED VOLUM

Comprehensive Dictionary

of PHYSICS

DICTIONARY OF

Material Science

and

High energy

physics

Comprehensive Dictionary

of Physics

Dipak Basu

Editor-in-Chief

Forthcoming and PUBLISHED VOLUMES

Dictionary of Pure and Applied Physics

a Volume in the Comprehensive Dictionary

and High energy

physics

Boca Raton London New York Washington, D.C.

CRC Press

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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

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 of Geophysics, Astrophysics, and Astronomy Each of these three dictionaries

is entirely self-contained

The aim of the DMSHEP is to provide students, researchers, academics, and professionals ingeneral with definitions in a very clear and concise form A maximum amount of information isavailable in this volume that is still of reasonable size The presentation is such that readers willnot 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 whenevernecessary

The fields covered in the DMSHEP are condensed matter, fluid dynamics, material science, nuclearphysics, quantum mechanics, quantum optics, plasma physics, and thermodynamics Terms havebeen chosen from textbooks, professional books, scientific and technical journals, etc The authorsare 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 thatold terms are not included in the DMSHEP, and new terminologies are not missed Some of theterms 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 physicsand 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 mation in the form of meanings of scientific terms presented in a very clear language and written

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text-Dipak Basu

University of North Carolina

Wilmington, North Carolina

Anupam Garg

Northwestern University Evanston, Illinois

Willi Graupner

Virginia Tech Blacksburg, Virginia

Muhammad R Hajj

Virginia Tech Blacksburg, Virginia

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

Bernard Zygelman

University of Nevada Las Vegas, Nevada

Editorial Advisor

Stan Gibilisco

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 Bis the Boltzmann

constant

absolute viscosity Measure of a fluid’s

resis-tance to motion whose constant is given by the

relation between the shear stress, 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-lation is not linear and apparent viscosity is used

absolute zero (0K) The lowest temperature

on the Kelvin or absolute scale

absorption A process in which a gas is sumed by a liquid or solid, or in which a liquid is

con-taken in by a solid In absorption, the substance

absorbed goes into the bulk of the material The

absorption of gases in solids is sometimes called

sorption

absorption band (F) If alkali halides areheated in the alkali vapor and cooled to roomtemperature, there will be a Farbe center defect.F-center is a halide vacancy with its bound elec-tron The excitation from ground state to the firstexcited 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 areheated in the halide vapor and cooled to roomtemperature, there will be a V-center defect in it.V-center is an alkali vacancy with its bound hole.The excitation from ground state to the first ex-

cited state in V-center causes a V-absorption band, which lies in the edge of ultra-vision light.

absorption coefficient A measure of theprobability that an atom will undergo a state-transition in the presence of electromagnetic ra-diation In modern atomic theory, an atom canmake a transition to a quantum state of higherenergy by absorbing quanta of photons The en-ergy defect of the transition is matched by theenergy 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) Lightincident on an atom can induce an upward tran-

sition of the atom’s state from an energy ε0to

an energy ε n = ε0+ ¯hω = ε0+ ¯hck, where

ω = (ε n − ε0)/ ¯h is the angular frequency of

the light, and k = 2π/λ its propagation

num-ber This is interpreted as the absorption of anindividual photon of energy¯hω = ε n −ε0by the

positive frequency component e −iωtof a

pertur-bation in the Hamiltonian of the atomic electron.The absorption cross section depends on the di-rection and polarization of the radiation, and is

r , t ) , and ε0, ε nare the energy of the initial

|0 > and final |n > atomic states.

absorption of plasma wave energy The loss

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 nian is invariant under the interchange of coor-dinates of a particle pair Eigenstates of such asystem are degenerate, and this property is calledexchange symmetry If a degeneracy exists that

Hamilto-is not due to exchange symmetry, it Hamilto-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 disdis-persion tion, there are optical and acoustical branches.Acoustical branches describe the relative mo-tion among primitive cells in crystal If thereare p atoms in each primitive cell, the number

rela-of acoustical modes is equal to the degree rela-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 tics is characterized by the analysis of linear gas

Acous-dynamic equations where wave motion is smallenough not to create finite amplitude waves Thefluid velocity is assumed to be zero

acoustic wave See sound wave

action A property of classical and tum dynamical systems In Hamilton’s for-mulation of classical dynamics, the quantity

quan-S = t2

t1 dt L(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 a value that is comparable to thevalue of Planck’s constant, the system exhibitsquantum behavior Feynman’s formulation ofquantum 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 Bis the Boltz-mann constant

added mass Refers to the effect of increaseddrag force on a linearly accelerating body For

a sphere (the simplest case to analyze), the drag

force in an ideal (frictionless) flow due to

accel-eration is

D= 2

3π r

3ρ dU dt

which is equivalent to increasing the volume of

the sphere by exactly 1/2 Thus, the increased

drag force may be neglected if the added mass

is included in the sphere to give a total mass of

(ρ+1

2ρ)V , where ρ is the fluid density and V

is the volume of the sphere Also referred to as

virtual mass

addition of angular momentum Two

an-gular momenta, J1 and J2 (orbital angular

mo-mentum and spin, or two distinguishable

sub-systems with different angular momentum

quan-tum numbers j1 and j2), can combine to yield

any quantized state with a total angular

momen-tum quanmomen-tum number in the range |j1 − j2| ≤

j ≤ (j1 +j2) but with the J z projections simply

adding as m = m1 +m2 The addition rules

fol-low from the nature of the angular momentum

where θ1φ1 and θ2φ2 are the polar and azimuthal

angles of particle 1 and 2, respectively, and P l

is a Legendre polynomial See associated

Leg-endre polynomial

adiabatic bulk modulus (β S ) The adiabatic

bulk modulus is a measure of the resistance to

volume change without deformation or change

in shape in a thermodynamic system in a process

with no heat exchange, i.e., at constant entropy

It is the inverse of the adiabatic compressibility:

adiabatic compressibility (κ s) The

frac-tional decrease in volume with increase in

pres-sure without exchange of heat, i.e., when the

entropy remains constant during the

adiabatic invariant Characteristic

parame-ter that does not change as a physical system

slowly evolves; the most commonly used batic invariant in plasma physics is the magnetic

adia-moment of a charged particle that is spiralingaround a magnetic field line

adiabatic plasma compression

Compres-sion of a gas and/or plasma that is not panied by gain or loss of heat from outside theplasma confinement system For example, plas-

accom-ma in an increasing accom-magnetic field that results inplasma compression slow enough that the mag-netic moment, or other adiabatic invariants ofthe plasma particles, may be taken as constant

adiabatic process A process in which no heat

enters or leaves a system

adiabatic theorem Describes the behavior of

the wave function for a system undergoing abatic evolution Consider a quantum systemwhose time evolution is governed by a Hamil-

adi-tonian H (R(t)), where R(t) is a non-quantum mechanical parameter and t is the time parame-

ter In the limit of slow evolution, so that the time

derivative of H (t) can be neglected, M Born and

V Fock showed that|(t) >= exp(− i

¯h

t

E(t )

dt ) |(0) >, where E(t) is the instantaneous

en-ergy eigenvalue for state|(t) >, is a solution to

the time dependent Schrödinger equation This

is a statement of the quantum adiabatic theorem

that was generalized in 1984 by M.V Berry See

Berry’s phase

adjoint equation A corresponding ship that results from replacing operators bytheir Hermitian conjugate, ordinary numbers bytheir complex conjugate, conjugating bras intokets (and kets into bras), and reversing withineach individual term the order of these symbols

relation-adjoint operator Property associated with a

pair of operators For operator A that has the property A |ψ >= |ψ >, where|ψ >, |ψ >

are vectors in Hilbert space, the operator A†is

called the adjoint operator of A It has the lowing property < ψ |A†=< ψ|, where < ψ|

fol-is the dual to vector|ψ > If A is a square

ma-trix, then A† is the matrix obtained by taking