The Anticoincidence Counter System of AMS-02

Abstract

The AMS-02 experiment will be installed on the International Space Station at an altitude of about 400 km in 2010 to measure for three years cosmic rays. The total acceptance including the electromagnetic calorimeter is 0.095 m$^2$sr. This work focuses on the anticoincidence counter system (ACC). The ACC is a single layer composed of 16 interlocking scintillator panels that surround the tracker inside the inner bore of the superconducting magnet. The ACC needs to detect particles that enter or exit the tracker through the sides with an efficiency of better than 99.99 %. This allows to reject particles that have not passed through all the subdetectors and may confuse the charge and momentum measurements which is important for an improvement of the antinuclei-measurements. In 2007/2008 all subdetectors were integrated into the AMS-02 experiment and atmospheric muons were collected. These data were used to determine the ACC detection efficiency.