Glossary

Search the Glossary by either clicking on a letter or typing a Keyword into the search box.

Annihilation (Positron - Electron)

Annihilation (Positron - Electron) radiation occurs when an electron (negatively charged) collides with a Positron (positively changed & the electron 'anti-particle'). The usual result is the emission of two gamma ray photons , each of 511 KeV and travelling away from each other. The example in this glossary shows the decay of F-18 by positron emission followed by the resulting annihilation radiation. This process has application in Positron Emission Tomography (PET imaging).

If you start from nothing, it is very difficult to get anywhere

– Gerhard Herzberg