Positron
The positron or antielectron is the particle with an electric charge of +1e, a spin of 1/2 (the same as the electron), and the same mass as an electron. It is the antiparticle (antimatter counterpart) of the electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons.
Cloud chamber photograph by C. D. Anderson of the first positron ever identified. A 6 mm lead plate separates the chamber. The deflection and direction of the particle's ion trail indicate that the particle is a positron. | |
| Composition | Elementary particle |
|---|---|
| Statistics | Fermionic |
| Generation | First |
| Interactions | Gravity, electromagnetic, weak |
| Symbol | e+ , β+ |
| Antiparticle | Electron |
| Theorized | Paul Dirac (1928) |
| Discovered | Carl D. Anderson (1932) |
| Mass | me 9.1093837015(28)×10−31 kg 5.48579909065(16)×10−4 Da 0.51099895000(15) MeV/c2 |
| Mean lifetime | stable (same as electron) |
| Electric charge | +1 e +1.602176634×10−19 C |
| Spin | 1/2 ħ (same as electron) |
| Weak isospin | LH: 0, RH: 1/2 |
Positrons can be created by positron emission radioactive decay (through weak interactions), or by pair production from a sufficiently energetic photon which is interacting with an atom in a material.
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