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Radiation Protection Glossary

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Positron
The positron has properties which are identical to those of a negatively charged Electron , except that it has a positive charge. Positrons are unstable in matter and disappear by Annihilation with negatively charged electrons. This produces two Gamma Rays , each of 0.511 MeV which move in opposite directions. In simple terms positron emitters (e.g. Oxygen-15) decay by a Proton changing into a Neutron and releasing a positron. One can say that the Nucleus of the parent has too much energy, but not enough to release an Alpha Particle and so releases a positron instead.