GeV to multi-TeV cosmic rays: AMS-02 status and future prospects

Due to recent observations, there is a renewed interest in GeV to multi-TeV cosmic ray measurements. Spectrum and composition measurements may in particular indicate dark matter contributions to the positron flux. Future instruments and their expected contributions to questions like cosmic ray origin, acceleration and propagation, as well as non-standard sources like dark matter or strangelets will enrich the observational base in the near future. The final flight set-up of the AMS-02 instrument is presented in detail and its performance is assessed. Its expected sensitivity to unusual sources of cosmic rays is estimated

Charge determination of nuclei with the AMS-02 silicon tracker

The silicon tracker of the AMS-02 detector measures the trajectory in three dimensions of electrons, protons and nuclei to high precision in a dipole magnetic field and thus measures their rigidity (momentum over charge) and the sign of their charge. In addition, it measures the specific energy loss of charged particles to determine the charge magnitude. Ladders from the AMS-02 tracker have been exposed to ion beams at CERN and GSI to study their response to nuclei from helium up to the iron group. The longest ladder, View the MathML source72×496mm2, verified in the tests contains 12 sensors. Good charge resolution is observed up to iro

The AMS-02 tracker performance

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Discriminating the source of high-energy positrons with AMS-02

We study the prospects for discriminating between the dark matter (DM) and pulsar origin of the PAMELA positron excess with the Alpha Magnetic Spectrometer AMS-02. We simulate the response of AMS-02 to positrons (and electrons) originating from DM annihilations, and determine the pulsar parameters (spin-down luminosity, distance and characteristic age) that produce a satisfactory fit to the mock AMS-02 data. It turns out that it is always possible to mimic a DM signal with pulsars. Although the fit in some cases requires values of spin-down luminosity and characteristic age different from those of known pulsars in the ATNF and Fermi-LAT catalogues, these catalogues are known to be incomplete, and therefore the pulsar interpretation can hardly be ruled out. We also show that if the positron excess is due to a single pulsar, it is always possible to find a DM candidate that provides a good fit to the mock AMS-02 data. The discrimination between the two scenarios will thus require a better knowledge of the underlying sources, or complementary data