Dresden 2013 – scientific programme

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T: Fachverband Teilchenphysik

T 113: Experimentelle Techniken der Astroteilchenphysik 6

T 113.4: Talk

Thursday, March 7, 2013, 17:40–17:55, HSZ-101

Positron-proton separation with the AMS-02 TRD — •Stefan Zeissler, Wim de Boer, Iris Gebauer, Melanie Heil, and Valerio Vagelli — KIT Karlsruhe

The Alpha Magnetic Spectrometer (AMS-02) is a state-of-the-art particle physics detector designed to operate as an external module on the International Space Station (ISS). Two of the main subdetectors are an Electromagnetic Calorimeter (ECAL) and a Transition Radiation Detector (TRD), the combination of which allows to select leptons with a rejection better than 10^5. Rejections as high as this are required to identify the very few positrons among the numerous cosmic rays protons. The TRD distinguishes positrons from protons by the transition radiation emitted when a charged particle crosses materials of different permitivity. The intensity of the transition radiation is proportional to the gamma-factor, which is detected as X-ray absorption in proportional tubes filled with Xe/CO2. To optimize the proton/positron separation multivariant approaches have been introduced. Here we show the results of a neural network approach which leads to a TRD-alone rejection of better than 10^3 above 10 GeV. This energy range is of particular interest for both, the study of local cosmic ray sources such as pulsars and indirect dark matter searches.