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Phys. Rev. Lett. 102, 051101 (2009) [5 pages]

New Measurement of the Antiproton-to-Proton Flux Ratio up to 100 GeV in the Cosmic Radiation

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O. Adriani et al. PAMELA Collaboration
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Received 13 September 2008; revised 21 November 2008; published 2 February 2009

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A new measurement of the cosmic-ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 above an energy of 20 GeV. The high-energy results are a tenfold improvement in statistics with respect to all previously published data. The data follow the trend expected from secondary production calculations and significantly constrain contributions from exotic sources, e.g., dark matter particle annihilations.

© 2009 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.102.051101
DOI:
10.1103/PhysRevLett.102.051101
PACS:
96.50.sb, 95.35.+d, 95.55.Vj