Mainz 2014 – scientific programme
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T: Fachverband Teilchenphysik
T 100: Niederenergie kosmische Strahlung
T 100.5: Talk
Thursday, March 27, 2014, 17:50–18:05, P2
Identifying positrons and electrons with AMS-02 — •Nikolas Zimmermann — RWTH Aachen University
The AMS-02 experiment is a multi-purpose detector for cosmic-ray particles mounted on the International Space Station. It recorded over 30 billion events since its installation in 2011.
Electrons are 100 times and positrons 1000 times less abundant than protons. Measuring the positrons as function of energy is especially interesting, as an excess over the expected astrophysical background may hint at an additional source of positrons in the galaxy or a new phenomena responsible for the excess.
In order to measure positrons accurately with a small uncertainty, a large proton rejection of 106 is needed. AMS-02 offers a transition radiation detector to separate positrons from protons and an electromagnetic calorimeter allowing a precise measurement of the kinetic energy of an incoming lepton. The misidentification probability of the charge sign, charge confusion, plays an important role when measuring electron and positron fluxes. The finite tracker resolution leads to an increasing probability to misidentify the charge sign at high energies and must be taken into account.
This talk covers the measurement of electron and positron fluxes with AMS-02 and its difficulties. Different techniques to obtain the electron and positron counting rates will be presented.