Cosmic-Ray Positron Identification through Bremsstrahlung Conversion

The main challenge of cosmic-ray positron measurements is the suppression of the vast proton background. An approach to the positron identification which is based on the reconstruction of pair production by bremsstrahlung photons is presented. It has been applied to data taken by the AMS-01 experiment and yields a proton rejection of more than 105, allowing to extend the positron sensitivity limit of the experiment from 3 GeV to 50 GeV.