THE ENERGY-SPECTRA AND RELATIVE ABUNDANCES OF ELECTRONS AND POSITRONSIN THE GALACTIC COSMIC-RADIATION

Observations of cosmic-ray electrons and positrons have been made with a new balloon-borne detector, the High-Energy Antimatter Telescope (H EAT), which was first flown in 1994 May from Fort Sumner, New Mexico. We describe the instrumental approach and the data analysis procedures , and we present results from this flight. The measurement has provide d a new determination of the individual energy spectra of electrons an d positrons from 5 GeV to about 50 GeV and of the combined ''all-elect ron'' intensity (e(+) + e(-)) up to similar to 100 GeV. The single pow er-law spectral indices for electrons and positrons are a = 3.09 +/- 0 .08 and 3.3 +/- 0.2, respectively. We find that a contribution from pr imary sources to the positron intensity in this energy region, if it e xists, must be quite small.