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annihilation radiation


Definition: the radiation resulting when a positron from beta-positive decay comes to rest. It encounters an electron, and the two particles annihilate each other and convert their rest mass into two 0.51-MeV gamma rays emitted in exactly opposite directions.

See: pair production

Further information

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.