High Statistics Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5-500 GeV with the Alpha Magnetic Spectrometer on the International Space Station


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Accardo L., Aguilar M., Aisa D., Alpat B., Alvino A., Ambrosi G., ...More

PHYSICAL REVIEW LETTERS, vol.113, no.12, 2014 (Peer-Reviewed Journal) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 113 Issue: 12
  • Publication Date: 2014
  • Doi Number: 10.1103/physrevlett.113.121101
  • Journal Name: PHYSICAL REVIEW LETTERS
  • Journal Indexes: Science Citation Index Expanded, Scopus

Abstract

A precision measurement by AMS of the positron fraction in primary cosmic rays in the energy range from 0.5 to 500 GeV based on 10.9 million positron and electron events is presented. This measurement extends the energy range of our previous observation and increases its precision. The new results show, for the first time, that above similar to 200 GeV the positron fraction no longer exhibits an increase with energy.