Threshold transition radiation detectors in astroparticle physics

Transition Radiation Detectors (TRDs) have been used to study highly relativistic cosmic rays in the last three decades. In recent and in future balloon or space experiments TRDs will be used as energy measuring or threshold devices with large acceptances and long flight durations. Energy measuring TRDs will be required to study the origin of high-energy particles in the cosmic rays at energies near 10 15 eV . Threshold TRDs will be used for particle identification which is a key issue for dark matter and SUSY searches relying on positron spectroscopy up to 300 GeV. This requires a proton rejection above 10 2 from the TRDs. A review will be given of the different requirements and experimental solutions for threshold TRDs and the astrophysical significance of their measurements. Special emphasis will be dedicated to the space qualification and long flight duration aspects of the AMS-02 TRD.