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where the 26.7 MeV includes the energy of the positrons emitted and annihilated.
https://openstax.org/books/college-physics-2e/pages/32-section-summary
Attempts to utilize controlled fusion as an energy source on Earth are related to deuterium and tritium, and the reactions play important roles.
https://openstax.org/books/college-physics-2e/pages/32-section-summary
Ignition is the condition under which controlled fusion is self-sustaining; it has not yet been achieved. Break-even, in which the fusion energy output is as great as the external energy input, has nearly been achieved.
https://openstax.org/books/college-physics-2e/pages/32-section-summary
Magnetic confinement and inertial confinement are the two methods being developed for heating fuel to sufficiently high temperatures, at sufficient density, and for sufficiently long times to achieve ignition. The first method uses magnetic fields and the second method uses the momentum of impinging laser beams for con...
https://openstax.org/books/college-physics-2e/pages/32-section-summary
Nuclear fission is a reaction in which a nucleus is split.
https://openstax.org/books/college-physics-2e/pages/32-section-summary
Fission releases energy when heavy nuclei are split into medium-mass nuclei.
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Self-sustained fission is possible, because neutron-induced fission also produces neutrons that can induce other fissions,n+AX→FF1+FF2+xnn+AX→FF1+FF2+xn, whereFF1FF1andFF2FF2are the two daughter nuclei, or fission fragments, andxis the number of neutrons produced.
https://openstax.org/books/college-physics-2e/pages/32-section-summary
A minimum mass, called the critical mass, should be present to achieve criticality.
https://openstax.org/books/college-physics-2e/pages/32-section-summary
More than a critical mass can produce supercriticality.
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The production of new or different isotopes (especially239Pu239Pu) by nuclear transformation is called breeding, and reactors designed for this purpose are called breeder reactors.
https://openstax.org/books/college-physics-2e/pages/32-section-summary
There are two types of nuclear weapons—fission bombs use fission alone, whereas thermonuclear bombs use fission to ignite fusion.
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Both types of weapons produce huge numbers of nuclear reactions in a very short time.
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Energy yields are measured in kilotons or megatons of equivalent conventional explosives and range from 0.1 kT to more than 20 MT.
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Nuclear bombs are characterized by far more thermal output and nuclear radiation output than conventional explosives.
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baryon number : a conserved physical quantity that is zero for mesons and leptons and±1±1for baryons and antibaryons, respectively
https://openstax.org/books/college-physics-2e/pages/33-glossary
baryons : hadrons that always decay to another baryon
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boson : particle with zero or an integer value of intrinsic spin
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bottom : a quark flavor
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charm : a quark flavor, which is the counterpart of the strange quark
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colliding beams : head-on collisions between particles moving in opposite directions
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color : a quark flavor
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conservation of total baryon number : a general rule based on the observation that the total number of nucleons was always conserved in nuclear reactions and decays
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conservation of total electron family number : a general rule stating that the total electron family number stays the same through an interaction
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conservation of total muon family number : a general rule stating that the total muon family number stays the same through an interaction
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cyclotron : accelerator that uses fixed-frequency alternating electric fields and fixed magnets to accelerate particles in a circular spiral path
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down : the second-lightest of all quarks
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electron family number : the number±1±1that is assigned to all members of the electron family, or the number 0 that is assigned to all particles not in the electron family
https://openstax.org/books/college-physics-2e/pages/33-glossary
electroweak theory : theory showing connections between EM and weak forces
https://openstax.org/books/college-physics-2e/pages/33-glossary
fermion : particle with a half-integer value of intrinsic spin
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Feynman diagram : a graph of time versus position that describes the exchange of virtual particles between subatomic particles
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flavors : quark type
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fundamental particle : particle with no substructure
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gauge boson : particle that carries one of the four forces
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gluons : eight proposed particles which carry the strong force
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gluons : exchange particles, analogous to the exchange of photons that gives rise to the electromagnetic force between two charged particles
https://openstax.org/books/college-physics-2e/pages/33-glossary
grand unified theory : theory that shows unification of the strong and electroweak forces
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hadrons : particles that feel the strong nuclear force
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Higgs boson : a massive particle that, if observed, would give validity to the theory that carrier particles are identical under certain circumstances
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leptons : particles that do not feel the strong nuclear force
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linear accelerator : accelerator that accelerates particles in a straight line
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meson : hadrons that can decay to leptons and leave no hadrons
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meson : particle whose mass is intermediate between the electron and nucleon masses
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muon family number : the number±1±1that is assigned to all members of the muon family, or the number 0 that is assigned to all particles not in the muon family
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particle physics : the study of and the quest for those truly fundamental particles having no substructure
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pion : particle exchanged between nucleons, transmitting the force between them
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quantum chromodynamics : quark theory including color
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quantum chromodynamics : the governing theory of connecting quantum number color to gluons
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quantum electrodynamics : the theory of electromagnetism on the particle scale
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quark : an elementary particle and a fundamental constituent of matter
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standard model : combination of quantum chromodynamics and electroweak theory
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strange : the third lightest of all quarks
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strangeness : a physical quantity assigned to various particles based on decay systematics
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superstring theory : a theory of everything based on vibrating strings some10−35m10−35min length
https://openstax.org/books/college-physics-2e/pages/33-glossary
synchrotron : a version of a cyclotron in which the frequency of the alternating voltage and the magnetic field strength are increased as the beam particles are accelerated
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synchrotron radiation : radiation caused by a magnetic field accelerating a charged particle perpendicular to its velocity
https://openstax.org/books/college-physics-2e/pages/33-glossary
tau family number : the number±1±1that is assigned to all members of the tau family, or the number 0 that is assigned to all particles not in the tau family
https://openstax.org/books/college-physics-2e/pages/33-glossary
theory of quark confinement : explains how quarks can exist and yet never be isolated or directly observed
https://openstax.org/books/college-physics-2e/pages/33-glossary
top : a quark flavor
https://openstax.org/books/college-physics-2e/pages/33-glossary
up : the lightest of all quarks
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Van de Graaff : early accelerator: simple, large-scale version of the electron gun
https://openstax.org/books/college-physics-2e/pages/33-glossary
virtual particles : particles which cannot be directly observed but their effects can be directly observed
https://openstax.org/books/college-physics-2e/pages/33-glossary
Yukawa’s idea of virtual particle exchange as the carrier of forces is crucial, with virtual particles being formed in temporary violation of the conservation of mass-energy as allowed by the Heisenberg uncertainty principle.
https://openstax.org/books/college-physics-2e/pages/33-section-summary
The four basic forces and their carrier particles are summarized in theTable 33.1.
https://openstax.org/books/college-physics-2e/pages/33-section-summary
Feynman diagrams are graphs of time versus position and are highly useful pictorial representations of particle processes.
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The theory of electromagnetism on the particle scale is called quantum electrodynamics (QED).
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A variety of particle accelerators have been used to explore the nature of subatomic particles and to test predictions of particle theories.
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Modern accelerators used in particle physics are either large synchrotrons or linear accelerators.
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The use of colliding beams makes much greater energy available for the creation of particles, and collisions between matter and antimatter allow a greater range of final products.
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All particles of matter have an antimatter counterpart that has the opposite charge and certain other quantum numbers as seen inTable 33.2. These matter-antimatter pairs are otherwise very similar but will annihilate when brought together. Known particles can be divided into three major groups—leptons, hadrons, and c...
https://openstax.org/books/college-physics-2e/pages/33-section-summary
Leptons do not feel the strong nuclear force and are further divided into three groups—electron family designated by electron family numberLeLe; muon family designated by muon family numberLμLμ; and tau family designated by tau family numberLτLτ. The family numbers are not universally conserved due to neutrino os...
https://openstax.org/books/college-physics-2e/pages/33-section-summary
Hadrons are particles that feel the strong nuclear force and are divided into baryons, with the baryon family numberBBbeing conserved, and mesons.
https://openstax.org/books/college-physics-2e/pages/33-section-summary
Hadrons are thought to be composed of quarks, with baryons having three quarks and mesons having a quark and an antiquark.
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The characteristics of the six quarks and their antiquark counterparts are given inTable 33.3, and the quark compositions of certain hadrons are given inTable 33.4.
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Indirect evidence for quarks is very strong, explaining all known hadrons and their quantum numbers, such as strangeness, charm, topness, and bottomness.
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Quarks come in six flavors and three colors and occur only in combinations that produce white.
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Fundamental particles have no further substructure, not even a size beyond their de Broglie wavelength.
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There are three types of fundamental particles—leptons, quarks, and carrier particles. Each type is divided into three analogous families as indicated inFigure 33.20.
https://openstax.org/books/college-physics-2e/pages/33-section-summary
Attempts to show unification of the four forces are called Grand Unified Theories (GUTs) and have been partially successful, with connections proven between EM and weak forces in electroweak theory.
https://openstax.org/books/college-physics-2e/pages/33-section-summary
The strong force is carried by eight proposed particles called gluons, which are intimately connected to a quantum number called color—their governing theory is thus called quantum chromodynamics (QCD). Taken together, QCD and the electroweak theory are widely accepted as the Standard Model of particle physics.
https://openstax.org/books/college-physics-2e/pages/33-section-summary
Unification of the strong force is expected at such high energies that it cannot be directly tested, but it may have observable consequences in the as-yet unobserved decay of the proton and topics to be discussed in the next chapter. Although unification of forces is generally anticipated, much remains to be done to pr...
https://openstax.org/books/college-physics-2e/pages/33-section-summary
axions : a type of WIMPs having masses about 10−10of an electron mass
https://openstax.org/books/college-physics-2e/pages/34-glossary
Big Bang : a gigantic explosion that threw out matter a few billion years ago
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black holes : objects having such large gravitational fields that things can fall in, but nothing, not even light, can escape
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chaos : word used to describe systems the outcomes of which are extremely sensitive to initial conditions
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complexity : an emerging field devoted to the study of complex systems
https://openstax.org/books/college-physics-2e/pages/34-glossary
cosmic microwave background : the spectrum of microwave radiation of cosmic origin
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cosmological constant : a theoretical construct intimately related to the expansion and closure of the universe
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cosmological red shift : the photon wavelength is stretched in transit from the source to the observer because of the expansion of space itself
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cosmology : the study of the character and evolution of the universe
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critical density : the density of matter needed to just halt universal expansion
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critical temperature : the temperature at which and below which a material becomes a superconductor
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dark matter : indirectly observed non-luminous matter
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electroweak epoch : the stage before 10−11back to 10−34after the Big Bang
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escape velocity : takeoff velocity when kinetic energy just cancels gravitational potential energy
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event horizon : the distance from the object at which the escape velocity is exactly the speed of light
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flat (zero curvature) universe : a universe that is infinite but not curved
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general relativity : Einstein’s theory that describes all types of relative motion including accelerated motion and the effects of gravity
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gravitational waves : mass-created distortions in space that propagate at the speed of light and that are predicted by general relativity
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GUT epoch : the time period from 10−43to 10−34after the Big Bang, when Grand Unification Theory, in which all forces except gravity are identical, governed the universe
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Hubble constant : a central concept in cosmology whose value is determined by taking the slope of a graph of velocity versus distance, obtained from red shift measurements
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