Positron

Positron

The Positron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of 1/2 (the same as the electron), and has the same mass as an electron. When a low-energy positron collides with a low-energy electron, annihilation occurs, resulting in the production of two or more gamma ray photons.

Discovery

The existence of positron was first postulated in 1928 by Paul Dirac as a direct consequence of the Dirac equation. In 1932, positrons were discovered by Carl D. Anderson, who gave the particle its name.

Characteristics

Positrons may be generated by positron emission nuclear decay (through weak interactions), or by pair production from a sufficiently energetic photon.

Applications

Positrons are used in medicine, specifically in positron emission tomography (PET) scans. These scans use a radioactive isotope that decays to produce positrons. The positrons annihilate to produce gamma rays, which are then detected and used to create an image of the body.

See also

• Antimatter
• Electron
• Gamma ray
• Positron emission
• Positron emission tomography

References

Positron Resources
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