Journal
NATURE
Volume 458, Issue 7238, Pages 607-609Publisher
NATURE PUBLISHING GROUP
DOI: 10.1038/nature07942
Keywords
-
Categories
Funding
- The Italian Space Agency (ASI)
- Deutsches Zentrumfur Luftund Raumfahrt (DLR)
- The Swedish National Space Board
- The Swedish Research Council
- The Russian Space Agency (Roscosmos)
- The Russian Foundation for Basic Research
Ask authors/readers for more resources
Antiparticles account for a small fraction of cosmic rays and are known to be produced in interactions between cosmic-ray nuclei and atoms in the interstellar medium(1), which is referred to as a 'secondary source'. Positrons might also originate in objects such as pulsars(2) and microquasars(3) or through dark matter annihilation(4), which would be 'primary sources'. Previous statistically limited measurements(5-7) of the ratio of positron and electron fluxes have been interpreted as evidence for a primary source for the positrons, as has an increase in the total electron+positron flux at energies between 300 and 600 GeV (ref. 8). Here we report a measurement of the positron fraction in the energy range 1.5-100 GeV. We find that the positron fraction increases sharply overmuch of that range, in a way that appears to be completely inconsistent with secondary sources. We therefore conclude that a primary source, be it an astrophysical object or dark matter annihilation, is necessary.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available