Cosmic ray electrons and positrons from 4.5 to 100 GeV.

Abstract

The HEAT (High Energy Antimatter Telescope) balloon borne cosmic ray experiment is described. The design, construction, flight and data analysis are discussed. The positron fraction (e$\rm\sp+/(e\sp+ +e\sp-)$ and the fluxes of electrons and positrons from 4.5 to 50 GeV and the flux of all electrons (electrons and positrons) from 4.5 to 100 GeV are presented. The positron fraction results do not confirm the previously observed rise. There is evidence for a statistically significant excess of positrons in the energy region of 7 GeV to 20 GeV. This excess is analyzed in the context of a Big Bang relic supersymmetric weakly interacting particle. The fluxes are found to be intermediate to previously reported measurements. The shape of all electron the spectrum is analyzed in the context of the Leaky Box cosmic ray propagation model.