Abstract
Precision measurements of the positron component in the cosmic radiation provide important information about the propagation of cosmic rays and the nature of particle sources in our Galaxy. The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray positron flux and fraction that extends previously published measurements up to 300 GeV in kinetic energy. The combined measurements of the cosmic-ray positron energy spectrum and fraction provide a unique tool to constrain interpretation models. During the recent solar minimum activity period from July 2006 to December 2009, approximately 24 500 positrons were observed. The results cannot be easily reconciled with purely secondary production, and additional sources of either astrophysical or exotic origin may be required.
- Received 19 June 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.081102
© 2013 American Physical Society
Synopsis
A Long, Hard Look at Cosmic-Ray Positrons
Published 19 August 2013
A satellite-based experiment has characterized the highest energy positrons contained in cosmic rays, which will help sort out astrophysical models for their origin.
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