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the antiparticle of the electron. When a positron is emitted by a radionuclide it combines with an electron and both undergo annihilation, producing two 511-keV gamma rays traveling in opposite directions. This effect is used in positron emission tomography.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

pos·i·tron (β+),

A subatomic particle of mass and charge equal to the electron but of opposite (that is, positive) charge.
Synonym(s): positive electron
Farlex Partner Medical Dictionary © Farlex 2012


+) (poz'i-tron)
A subatomic particle of mass and charge equal to the electron but of opposite (i.e., positive) charge.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


One of the small particles that make up an atom. A positron has the same mass and amount of charge as an electron, but the positron has a positive charge.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
According to Positron's president, Adel Abdullah, the demand for PET imaging is continuing to accelerate and increasing the need for radiopharmaceuticals and imaging technology.
Positron emission tomography is the diagnostic medical procedure of producing a positron emission tomography scan to examine metabolic activity of the tissues particularly the brain tissue, using a radioactive isotope administered intravenously.
By performing experiments using three laser systems -- Titan at Lawrence Livermore, Omega-EP at the Laboratory for Laser Energetics, and Orion at Atomic Weapons Establishment (AWE) in the United Kingdom -- LLNL physicist Hui Chen and her colleagues created nearly a trillion positrons (also known as anti-matter particles).
After again employing two separate teams to comb through the data, he confirmed the positron excess detected by HEAT, PAMELA and Fermi (SN: 5/4/13, p.14).
They would then direct the photon beam from the first stage of the experiment through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can.
These studies were triggered by the observation of a 1.8 MeV mono-energetic positron peak in heavy-ion collisions at GSI in 1983 15].
If Wimps exist, they would annihilate each other when they collide to release electrons and their antimatter equivalent, positrons.
Near-surface depth profiling of solids by mono-energetic positrons.
The latter are potential sites for investigation by positron annihilation experiments.
(5,6) When the asymmetric energy collider project started, there was also a study group which intended to build a B-factory using the symmetric energy collision of electron and positron beams using the 6.5 GeV TRISTAN accumulation ring.
Sure enough, these frequencies appeared to flip the spin of the positron and eject the antihydrogen from the trap.