annihilation

annihilation

A reaction between an elementary particle and its antiparticle in which the two particles disappear and photons or other particles and antiparticles are created; energy and momentum are conserved. An electron and a positron, for example, interact and produce two gamma-ray photons. Hadrons, such as the proton and the antiproton, also undergo annihilation, as do quarks and antiquarks.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

annihilation

[ə‚nī·ə′lā·shən]

(particle physics)

A process in which an antiparticle and a particle combine and release their rest energies in other particles.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.