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Topic: Antiparticle

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In the News (Thu 25 Apr 19)

  antiparticle - Encyclopedia.com   (Site not responding. Last check: 2007-11-02)
antiparticle elementary particle corresponding to an ordinary particle such as the proton, neutron, or electron, but having the opposite electrical charge and magnetic moment.
In a few cases, such as the photon and the neutral pion, the particle is its own antiparticle, but most antiparticles are distinct from their ordinary counterparts.
The existence of antiparticles for electrons was predicted in 1928 by P. Dirac's relativistic quantum theory of the electron.
www.encyclopedia.com /doc.aspx?id=1E1:antipart   (720 words)

 antiparticle. The New Dictionary of Cultural Literacy, Third Edition. 2002
In physics, a rare form of subatomic matter that is a mirror image of normal matter.
The antiparticle corresponding to an elementary particle has the same mass as the particle but is opposite in all other properties.
The antiparticle corresponding to an electron is a positron, which has the same mass as an electron but a positive charge.
www.bartleby.com /59/19/antiparticle.html   (214 words)

 Antiparticle -- from Eric Weisstein's World of Physics
Antiparticles are denoted my placing a bar above the symbol for a given particle.
It gradually become clear that every particle has a corresponding antiparticle with the same mass and spin but, for charged particles, with a charge (and other quantum numbers) of the opposite sign.
When a particle meets its antiparticle, they can annihilate each other and disappear, their combined rest energies becoming available to appear in other forms.
scienceworld.wolfram.com /physics/Antiparticle.html   (232 words)

 ATLAS - eNews   (Site not responding. Last check: 2007-11-02)
antiparticle: For every fermion type there is another fermion type that has exactly the same mass but the opposite value of all other charges (quantum numbers).
For example, the antiparticle of an electron is a particle of positive electric charge called the positron.
Bosons also have antiparticles, except for those that have zero value for all charges, for example, a photon or a composite boson made from a quark and its corresponding antiquark.
pdg.lbl.gov /atlas/glossary.html   (2740 words)

 Theory: Antiparticles (SLAC VVC)
A particle and its antiparticle have identical mass and spin.
The antiparticle of a photon is a photon, likewise the antiparticle of a phi meson (s quark and anti-s quark) is a phi meson.
During any process, the number of particles plus antiparticles of a related type are conserved -- their total is the same before and after the process.
www2.slac.stanford.edu /vvc/theory/antiquarks.html   (625 words)

 antiparticle concept from the Astronomy knowledge base   (Site not responding. Last check: 2007-11-02)
Most of the observable universe consists of particles and matter, as opposed to antiparticles and antimatter.
The antiparticle of an electrically neutral particle is sometimes the same as the original particle (e.g., photons) and sometimes it is distinct (e.g., neutrons).
For each particle, there must exist an antiparticle with the opposite charge, magnetic moment and other internal quantum numbers (e.g., lepton number, baryon number, strangeness, charm, etc.), but with the same mass, spin and lifetime.
www.site.uottawa.ca:4321 /astronomy/antiparticle.html   (374 words)

 antiparticle - Search Results - MSN Encarta
Antiparticles, particles that are counterparts of the elementary particles that make up ordinary matter.
Unlike neutrinos and some other electrically neutral particles, the photon does not have a distinct antiparticle.
When an antiparticle and its particle interact, mutual annihilation occurs.
encarta.msn.com /antiparticle.html   (124 words)

 [No title]   (Site not responding. Last check: 2007-11-02)
An antiparticle that passes through a TOF system is slowed down by dE/dx losses in a degrader block.
The antiparticle is eventually stopped in the gas chamber, forming an exotic atom.
Once the antiparticle is captured into an bound state of the atom due to its negative charge, it starts decaying toward the nucleus.
www.cita.utoronto.ca /~kaya/exotic.html   (191 words)

 Antiparticle - Wikipedia, the free encyclopedia
Some particles, such as the neutron, are identical to their antiparticle; such particles must have no electric charge, but not all charge-neutral particles are of this kind.
A unified interpretation of antiparticles is now available in quantum field theory, which solves both these problems.
This behaviour under CPT is the same as the statement that the particle and its antiparticle lie in the same irreducible representation of the Poincare group.
en.wikipedia.org /wiki/Antiparticle   (1589 words)

 ScienceDaily: New Particle Discovered By BaBar Experiment, Revealing Secrets Of Strong Force
Physicists have known since some time that for each particle, an antiparticle exists, nearly identical in all aspects, except for some properties that are opposite.
The antiparticle of the electron is for instance the positron, named also antielectron, provided with positive electric charge, rather than negative.
During the 50's it was although discovered that particles can be made up also of the combination of a fundamental particle and its corresponding antiparticle.
www.sciencedaily.com /releases/2005/07/050712234420.htm   (913 words)

 Virtual antiparticle pairs at event horizon
His question was: Why does the antiparticle counterpart of the virtual antiparticle pairs (those that appear due to uncertainty between time and energy) at the event horizon fall into the fl hole, instead of the 'particle' counterpart of the pair (for example: a 'particle' is an electron, an antiparticle is the positron)?
During the pair creation, the particle or the antiparticle has the ability to fall within the event horizon and therefore has the ability to be separated from its pair.
Antiparticles have the same mass as particles -- there is no such thing as negative mass.
www.physicsforums.com /showthread.php?p=226260   (1480 words)

 The "W" Particle and the Weak Force Mechanism
In addition, notice that in the baryon decays a particular meson is always necessary to both annihilate and supply a specific quark flavor in the baryon being transformed.
The antiparticle of this reacting meson always appears among the product particles, suggesting that the proposed mechanism is in fact the actual pathway.
Hence although the virtual particle x antiparticle complex is identical in both the "short" and "long" decay sequences, the products are different because the "short" annihilates one member of its virtual complex, whereas the "long" does not.
home.earthlink.net /~johngowan/weakforce.html   (3145 words)

 Antiparticles   (Site not responding. Last check: 2007-11-02)
For example, the positron is the antiparticle of the electron.
Going beyond the basics, we can say that an antiparticle is related to the particle by charge conjugation.
If the neutral kaon is confirmed to directly violate CP, it may provide an avenue for nature to show a preference for matter over antimatter in the early universe.
hyperphysics.phy-astr.gsu.edu /hbase/particles/antimatter.html   (275 words)

 Particle Adventure Glossary   (Site not responding. Last check: 2007-11-02)
The energy appears in some other form, perhaps as a different particle and its antiparticle (and their energy), perhaps as many mesons, perhaps as a single neutral boson.
The produced particles may be any combination allowed by conservation of energy and momentum and of all the charge types.
Most boson types also have antiparticles except for those that have zero value for all charges, such as a photon or a composite boson made from a quark and its corresponding antiquark.
www.particleadventure.org /particleadventure/frameless/glossary.html   (1995 words)

 antimatter - a Whatis.com definition   (Site not responding. Last check: 2007-11-02)
Antimatter is any substance that, when combined with an equal amount of matter, results in the complete and direct conversion of all substance to energy.
The antiparticle of an electron is known as a positron.
An antiparticle never lasts for very long, because shortly after it forms, it encounters one of its equivalent matter particles, and both are annihilated, yielding pure energy.
whatis.techtarget.com /gDefinition/0,294236,sid44_gci866279,00.html   (287 words)

 Antimatter   (Site not responding. Last check: 2007-11-02)
In general, an antiparticle is the particles name with "anti" in front of it.
For example, the antiparticle of the proton is the antiproton.
An exception to this rule is the electron, whose antiparticle is known as the positron.
blueflag.phys.yorku.ca /yhep/antimatter.html   (161 words)

 Glossary Test
A process in which a particle meets its corresponding antiparticle and both disappear.
For most particle types there is another particle type that has exactly the same mass but the opposite value of all other charges.
Matter made up of elementary particles whose masses are identical to their normal-matter counterparts but whose other properties, such as electric charge, are reversed.
www.cpepweb.org /main_universe/glossary.html   (2139 words)

 The Quark-Lepton Era
, where E is the energy of the photon and m is the mass of the particle and antiparticle).
At this time the universe has a baryon-antibaryon asymmetry which results from post-inflationary violating processes, explained in terms of of decay a hypothetical X-boson resulting from an asymmetry in the electro-weak force.
So they are frozen out, just as the baryons were, and like the baryons then proceed annihilate each other, only one out of every billion electrons surviving, and the electron era camme toi an end.
www.kheper.net /cosmos/universe/Quark-Lepton.html   (740 words)

 UCT Physics: Elementary Particle Physics Glossary   (Site not responding. Last check: 2007-11-02)
A synchrotron (such as the SPS at CERN) uses magnetic fields to confine the proton orbits to a circle, and electric fields in radio-frequency cavities to accelerate the charge protons.
The energy appears in some other form, perhaps as a different particle and its antiparticle (and their energy), perhaps as many mesons, perhaps as a single neutral boson, or perhaps as gamma rays.
The electrically-charged leptons are the electron, the muon, the tau, and their antiparticles.
www.phy.uct.ac.za /courses/phy400w/particle/ppgloss.htm   (2398 words)

 [No title]
The gaseous antiparticle spectrometer (GAPS) effects particle identification through the characteristic X-rays emitted by antiparticle when it forms exotic atoms in gases.
The antiparticle is eventually stopped in the gas chamber, forming an exotic atom with probability of order unity (excluding a small fraction of loss by the direct annihilation in degrader block and gas).
Promptly after the release of these X-rays, the antiparticle annihilates with the proton producing a shower of pions.
www.cita.utoronto.ca /~kaya/gaps.html   (463 words)

 A Beginner's Guide to Antimatter   (Site not responding. Last check: 2007-11-02)
When a particle and its antiparticle meet, they annihilate each other and their entire mass is converted into pure energy.
Dirac's equations predicted that all of the fundamental particles in nature must have a corresponding "antiparticle." In each case, the masses of the particle and antiparticle are identical, and other properties are nearly identical.
Present theory suggests that if particles outnumbered antiparticles in the Big Bang by as little as one part in 100 million, then the present universe could be explained by those extra particles that were not annihilated by an antiparticle counterpart.
www.firstscience.com /site/articles/antimatter.asp   (981 words)

 Particle-Antiparticle Asymmetry, CP Violation, and B Factories
There has already been detected an asymmetry between particles and antiparticles in the K meson system, by Val Fitch and Jim Cronin in 1980.
The symmetry that exchanges a particle and antiparticle is called charge conjugation, C, because the charges change sign under this.
Because these are more massive than kaons, there are fewer strong interacting states to couple to the B's, and the measurements in the B system are almost an exact test of the quark mixing theory in the weak interactions, as opposed to the kaon system which is very complicated by strong interactions.
www.ps.uci.edu /physics/news3/silverman.html   (763 words)

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