Leptons in near earth orbit

The lepton spectra in the kinetic energy ranges 0.2 to 40 GeV for e(-) and 0.2 to 3 GeV for e(+) were measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380 km. From the origin of the leptons two distinct spectra were observed: a higher energy spectrum and a substantial second spectrum with positrons much more abundant than electrons. Tracing leptons from the second spectra shows that most of these leptons travel for an extended period of time in the geomagnetic field and that the e(+) and e(-) originate from two complementary geographic regions. (C) 2000 Elsevier Science B.V. All rights reserved.