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Topic: Positron

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  Positron - Wikipedia, the free encyclopedia
When a low-energy positron collides with a low-energy electron, undergoing an annihilation event, their mass is converted into the kinetic energy of two gamma ray photons (see electron-positron annihilation).
The existence of positrons was first postulated in 1928 by Paul Dirac as an inevitable consequence of the Dirac equation.
Anderson also unsuccessfully suggested renaming electrons "negatrons." The positron was the first evidence of antimatter and was discovered by passing cosmic rays through a gas chamber and a lead plate surrounded by a magnet to distinguish the particles by bending differently charged particles in different directions.
en.wikipedia.org /wiki/Positron   (468 words)

 Positron (City of Heroes) - Wikipedia, the free encyclopedia
Positron (Dr. Raymond Keyes) is a fictional superhero from the City of Heroes backstory.
During this arc in the series, Positron and Synapse would become entrusted in protecting Candy Lebeaux, one of three people with the cosmic potential the Circle of Thorns needed to summon their patron god.
Positron has the ability to general and control anti-matter, which upon contact with regular matter, generally explodes.
en.wikipedia.org /wiki/Positron_(City_of_Heroes)   (1116 words)

 Positron Physics at COMP
The positron is the antiparticle of the electron: it has the same mass as the electron but its charge is positive.
Then the positron is in a quantum-mechanical state in which the strong positron - positive nuclei repulsion is a prominent feature pushing the positron density away from ion core regions.
If the positron is trapped by a vacancy-type defect in a solid its lifetime increases from that of a delocalized positron due to the reduced electron density.
www.fyslab.hut.fi /epm/positron/pos.html   (760 words)

 The LLNL Electron-Positron Beams Facility   (Site not responding. Last check: 2007-10-22)
The positron facility provides a wide range of capabilities, including high-current beams for investigation of bulk materials properties, low-emittance beams for studies of one-component plasmas, and a positron microprobe.
Experiments underway at the positron facility are probing the mechanisms by which defects arise in materials, of vital importance for science-based stockpile stewardship in this era of a comprehensive ban on nuclear weapons testing.
Two-photon annihilation is the dominant decay mode for positrons in a material; unless a positron collides with an electron, it is stable.
www-phys.llnl.gov /H_Div/Positrons   (275 words)

 The LLNL Electron-Positron Beam Facility   (Site not responding. Last check: 2007-10-22)
The positron facility at LLNL is designed to produce positrons with a wide range of characteristics, and to deliver them to a number of experimental apparatuses.
Tungsten has a negative "work function" for positrons; positrons in the material are ejected from the surface with an energy distribution approximately equal to that of the electrons in the material.
Positrons produced in the linac target are captured into a "stretcher," which reduces their energy and intensifies the pulses.
www-phys.llnl.gov /H_Div/Positrons/PositronFacility.html   (710 words)

 Lamination--Plastic Lamination and Decorative Paint Films By Positron Corp.   (Site not responding. Last check: 2007-10-22)
Positron Corporation laminates most of the beautiful foils and films found on its own switch and instrument panels.
Positron has developed a method to laminate chrome foil to thick sheet ABS and TPO which can later be thermo-formed into products such as bumpers and grills for vehicles.
Positron is capable of laminating vac-formable foam to plastic sheets which are then formed into items such a fender covers or "dunnage" products.
positroncorp.com /Lamination.html   (308 words)

 Nuclear Physics and Tomography   (Site not responding. Last check: 2007-10-22)
Positron emission stabilizes the nucleus by removing a positive charge through the conversion of a proton into a neutron.
The positron combines with an ordinary electron of a nearby atom in an annihilation reaction, forming positronium as an intermediate.
When a positron comes in contact with an electron, the two particles annihilate turning the mass of the two particles into two 511-keV gamma-rays that are emitted at 180-degree to each other.
laxmi.nuc.ucla.edu:8000 /lpp/nuclearphysics/imagerecon.html   (685 words)

 Positron Emission Tomography
Positron emission tomography (PET scan) is a test that combines computed tomography (CT) and nuclear scanning.
A positron emission tomography (PET) scan is done in a hospital nuclear medicine department or at a special PET center by a radiologist or nuclear medicine specialist and a nuclear medicine technologist.
Positron emission tomography (PET) scanning is not usually recommended during pregnancy because the radiation could damage a developing fetus.
www.webmd.com /hw/health_guide_atoz/aa80345.asp   (1684 words)

 Define positron - a definition from Whatis.com
A positron is a particle of matter with the same mass as an electron, but opposite charge.
It is a form of antimatter because, when a positron encounters an electron, the two completely annihilate to yield energy.
The existence of the positron was predicted in 1928 by physicist Paul Dirac, and positrons were discovered experimentally in 1932 by physicist Carl Anderson.
whatis.techtarget.com /definition/0,,sid9_gci869317,00.html   (214 words)

 UTA Physics - Positron Surface Group
Positron annihilation induced Auger electron spectroscopy studies of properties of an alkali-metal overlayer on the Cu(100) surface, N.G. Fazleev, J.L. Fry, J.H. Kaiser, A.R. Koymen, K.H. Lee, T.D. Niedzwiecki, and A.H. Weiss, Phys.
Positron states and annihilation characteristics at the (100), (110), and (111) surfaces of alkali metals, N. Fazleev, J. L Fry, and Alex Weiss, Phys.
Positrons as probes of Si(100) surface with adsorbed hydrogen and oxygen, Fazleev, N. G.; Fry, J. L.; Weiss, A. H Radiation Physics and Chemistry, 58, 659-665 (2000).
www.uta.edu /physics/main/faculty/weiss/psg/publications   (2235 words)

 Positron | Legal Notice
Positron makes no representation that the Content in the Site is appropriate or available for use in other locations, and access to it from territories where the Content is illegal is prohibited.
Positron is not granting you any permission to use the Content other than the permission expressly stated in these Web Site Terms of Use.
The "P", Positron, and marks shown with a ® are owned by Positron, or their respective owners, and registered with the U.S. Patent and Trademark Office.
www.positron911.com /legal.asp   (962 words)

 Positron Accumulator
The ATHENA Positron Accumulator accumulates its positrons from a slow positron beamline that is a technological evolution of those early concepts of how to make a positron beam.
Positrons are not a common occurrence in nature, just like any other form of antimatter.
Since a positron beam originating from a radioactive source is by nature continious we can not use a method with opening and closing a gate electrode like we do for the antiproton pulses.
athena-positrons.web.cern.ch /ATHENA-positrons/wwwathena/Positron_accumulator.html   (864 words)

 Positron Public Safety Systems | The Power to Respond™
Positron Public Safety Systems' fully-integrated suite of applications span the entire workflow of public safety - from E9-1-1 emergency response to command and control through to digital justice and corrections.
Positron systems do more, share more and work together, right out of the box.
Positron's approach is the only path to an affordable, feature rich and evolving system - with a single number to call when you need expansion or support.
www.positron911.com   (116 words)

 Positron S.A. - The leader in Software and Web Development
Positron is aware of the inherent business opportunities of the Information Technologies and continuously evolves to be in best position to use new technologies as they emerge.
Positron specializes in the design and development of Commercial, Educational and Information Web Portals taking advantage of new technologies of web based appearance and content management using software and platforms of strategic collaborators such as Sun Microsystems for the products of Sun ONE.
Positron monitors all emerging information technologies as well as the evolution in the area of business computing.
www.positron.gr /about/aboutenglish.htm   (629 words)

Positron was kept afloat with bridge financing from Imatron Corporation in South San Francisco.
Because Positron PET is the best technique for measuring and imaging the impact of these diseases in the human body, better than CT, better than MR, better than Ultrasound, better than SPECT.
Positron is a whole body PET unit and offers some major competitive advantages.
www.twst.com /ceos/posc.html   (3044 words)

 T.L. Gibson's Positron-Matter Interactions Page
Though it is tempting to think of a positron as just a "positive electron" in terms of its interaction with atoms and molecules, there are significant differences that are most apparent at low and intermediate energies.
One of the most interesting phenomena in the field of positron collisions with matter---and one that has no electron-scattering counterpart---is the formation of real and virtual positronium (Ps) and the manner in which this charge-exchange process affects the elastic scattering.
A new treatment of short-range correlation between the positron and the electrons of the target.
www.phys.ttu.edu /~ritlg/research/pos1.html   (360 words)

 UTA Physics - Positron Surface Group
Positron Stimulated Secondary Electron Emission from Cu (100), Alex H. Weiss and Karl Canter, in Positron Annihilation, the proceedings of the Sixth International Conference on Positron Annihilation,edited by P.G. Coleman, S.C. Sharma and L.M. Diana, North Holland Publishing Co. (1982) pp.
Positron Annihilation Induced Auger Electron Spectroscopy, Alex Weiss, in Positron Beams for Solid and Surfaces, AIP Conference Proceedings 218, edited by P.J. Schultz, G. Massoumi, and P.J. Simpson, AIP Press, New York (1990).
Positron States on the Cs/Cu(100) Surface, A.R. Koymen, K.H. Lee, D. Mehl, Alex Weiss, and K.O. Jensen, in Positron Beams for Solids and Surfaces, AIP Conference Proceedings 218, edited by P.J. Schultz, G. Massoumi, and P.J. Simpson, AIP Press, New York (1990) pp.
www.uta.edu /physics/main/faculty/weiss/psg/publications/pubproc.html   (906 words)

 Accelerator: Positron Beam   (Site not responding. Last check: 2007-10-22)
Positrons are produced by diverting some of the electrons
The positrons are collected and sent back along a separate line to the start of the linac.
At the beginning of the linac, magnets turn the positrons around and send then into the linac where they are accelerated in just the same way as electrons.
www2.slac.stanford.edu /vvc/accelerators/positron.html   (100 words)

 Black Diamond Positron Anodized Carabiner
Black Diamond designed the Positron Anodized Carabiner to bring the anti-snag benefits of a keylock biner to the ‘working class' climber.
The Positron's keylock nose doesn't snag on pro, ropes, or slings—which translates to easier clips and reduces the chance of open-gate failure.
The functional shape of the Positron makes it easy to hold, and its bowed back, smooth action, and deep basket add up to make this the most versatile clipping, racking and anchoring biner ever.
www.backcountry.com /store/BLD0610.html?PID=1692154&AID=10281785   (326 words)

 Ilham Alqaradawi - Physics - Positron Group
As this will be the first equipment of its type in the region (the three other nearest positron beams are in Italy, South Africa and India), regional collaboration with other groups working on other problems in material physics will be encouraged.
To achieve this, a major aspect of the project will be the training of students in the latest techniques and the development of local expertise and a major objective will be to study problems of relevance to local industry.
For more information on positron research at the University of Qatar click here or contact the project leader.
www.ilhamalqaradawi.com /positron-group/positron_beam_project.htm   (258 words)

 [No title]
Positron allows you to individually add and delete tracks from a Neuros, as well as synchronize it with a directory tree of music.
Most people will use "positron sync" to copy over all of their music directories (specified when you ran "positron config").
Positron will try to figure out where everything should be filed, but with the following limitations: * The pcaudio database will be cleared.
www.xiph.org /positron/files/README   (806 words)

 Universe Today - Positron Drive: Fill 'er Up For Pluto
Unlike human twins, a positron is unlikely to survive the birth process.
Because positrons and their siblings - electrons - find each other irresistible and quickly annihilate in a burst of soft gamma rays.
According to Dr. Smith, "for many years physicists have squeezed positrons out of the tungsten targets by colliding the positrons with matter, slowing them down by a thousand or so to use in high resolution microscopes.
www.universetoday.com /am/publish/positron_drive_pluto.html   (1146 words)

 Hifi Choice - Review   (Site not responding. Last check: 2007-10-22)
The averaged room responses show that the Positron's bass alignment is well suited to free-space siting, although some wall proximity is unlikely to do much harm.
The Positron received very similar marks and comments on two separate presentations, when the panel showed unusual unanimity and consistency in placing it a little below average overall.
In acoustic terms, Positron is the smallest speaker within the test group, and suffers somewhat when compared to significantly larger alternatives available at a similar price.
www.hifichoice.co.uk /archive/perl/426_printreview.htm   (566 words)

 Positron Technologies Inc.
Positron Technologies Inc. is a leader in the electronics manufacturing services and logistics market place in Canada.
When these core competencies are combined with our state of the art manufacturing technologies and programs, Positron becomes a clear choice for strategic partnership engagements.
Positron is continuously working to drive costs out there by increasing our customer's competitiveness within their market place.
www.positron-tech.com   (97 words)

 The Positron from Garrison Aerodrome
Designed by Pat Mattes of Mattes Models for Garrison Aerodrome, the Positron is an intermediate level Speed 400 class electric sport model constructed primarily of balsa sheet.
The Positron builds quickly since the wing is flat and there are no ribs.
We have a slick, interactive 3-D wireframe of the Positron available.
www.rc-aero.com /kits/positron   (199 words)

 Technorati Tag: Positron
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www.technorati.com /tag/Positron   (283 words)

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