Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published July 16, 1992 | public
Journal Article

The big accelerator in the sky

Abstract

The positron, the antimatter counterpart of the electron, was discovered on 2 August 1932, dramatically and unexpectedly confirming Dirac's new quantum theory of the electron. The positron in question was created by a cosmic ray which happened to end its wanderings around the Galaxy in the Caltech cloud chamber of Carl Anderson. Astrophysical objects, which have been accelerating particles for much longer and to much higher energies than have terrestrial physicists, can be astonishingly efficient. Near the centre of our Galaxy, some object (or objects) can, when it chooses, create 10^(10) tonnes of positrons per second, with very little waste heat. The positrons, of rest-mass energy 511 keV, annihilate with the electrons they meet, often releasing a pair of 511-keV γ-rays. The 20-year search for the source of these positrons takes an unexpected turn on page 215 of this issue.

Additional Information

© 1992 Nature Publishing Group.

Additional details

Created:
August 20, 2023
Modified:
March 5, 2024