Würzburg 2018 – scientific programme

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T: Fachverband Teilchenphysik

T 7: Kosmische Strahlung I

T 7.9: Talk

Monday, March 19, 2018, 18:05–18:20, Philo-HS7

Cosmic ray anisotropy searches with AMS-02 — Iris Gebauer, Kai Fabian Bindel, Maura Graziani, and •Stefan Zeissler — Karlsruher Institut für Technologie (KIT)

The Alpha Magnetic Spectrometer (AMS-02) is a state-of-the-art particle detector designed to operate as an external module on the International Space Station (ISS). In this unique space environment, cosmic particles can be measured with high precision over an energy range from GeV up to TeV. The AMS collaboration provided precise measurements of the electron and positron fluxes, which indicate an additional source of positrons among the various cosmic particles. Possible candidates for such a source are local pulsars, a local source of positrons produced in proton-gas interactions or dark matter annihilation. In the first two cases, a possible anisotropy in the electrons and positrons incoming direction at Earth might be detectable. To determine the level of isotropy, the measured data is compared to reference maps, which simulate a measurement of the isotropic sky. A common choice of reference maps are proton count maps or shuffled maps, which redistribute measured incoming directions over the whole measuring time. Both options lead to difficulties in the reconstruction of a marginal signal with large expansion over the galactic sky as it would be the case for charged cosmic particles. We developed a method to construct reference maps based on fundamental detector characteristics such as the livetime and the geometric acceptance. Using this, we are able to reconstruct the isotropic sky as it would be seen by the detector. We demonstrate the performance of the method using AMS-02 data.