First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–350 GeV
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Aguilar-2013-First Result from the Alpha Magnetic S.pdf
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Author(s)
Basil, A.
Becker, R.
Becker, Ulrich J.
Behlmann, Matthew Daniel
Berges, P.
Burger, Joseph D.
Cai, X. D.
Capell, Michael H.
Chen, Andrew I.
Chen, H.
Date Issued
April 2013
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Aguilar, M. et al. “First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–350 GeV.” Physical Review Letters 110.14 (2013). © 2013 American Physical Society
Version
Final published version
Abstract
A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8×10[superscript 6] positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼250 GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.110.141102
