The AMS-02 transition radiation detector

The Alpha Magnetic Spectrometer AMS02 will be equipped with a large transition radiation detector (TRD) to achieve a proton background suppression necessary for dark matter searches. The AMS02 TRD consists of 20 layers of fleece radiator each with Xe/CO2 proportional wire straw tubes read out by a dedicated low-power data-acquisition system. A space-qualified TRD design will be presented. The performance of a 20-layer prototype was tested at CERN with electron, myon and pion beams up to 100 GeV and with protons up to 250 GeV. The beam-test results will be compared to Geant3 MC predictions. The detector is under construction at RWTH Aachen; the gas system will be built at MIT, slow-control at MIT and INFN Rome and DAQ at TH Karlsruhe. This project is funded by the German Space Agency DLR, the US Department of Energy DOE and NASA. (C) 2004 Elsevier B.V. All rights reserved.