Precision measurement of the positron fraction in primary cosmic rays with the AMS-02 detector
Aula Bruno Touschek (LNF INFN)
Aula Bruno Touschek
Via Enrico Fermi, 40
Alpha Magnetic Spectrometer (AMS-02) is a general purpose high energy particle detector which was successfully deployed on the International Space Station (ISS) on May 19, 2011 to conduct a long duration
mission of fundamental physics research in space.
The results of the AMS experiment on the primary positron fraction in the energy range from 0.5 to 350 GeV are presented. Events have been collected in the first 18 months of data taking, for a total statistics of ~6 million electrons and ~600,000 positrons. The data show that the positron fraction is steadily increasing from 10 to ~250 GeV. The positron fraction spectrum shows no structure and the positron to electron ratio shows no observable anisotropy.