Cosmic-ray electron flux from 10 to 100 GeV measured by the bets instrument

Abstract New measurements of the electron flux from 10 to 100 GeV were carried out with the BETS (balloon-borne electron telescope with scintillating fibers) instrument. The detector is an imaging calorimeter consisting of scintillating-fiber belts of 36 layers (each 280 mm wide) and the 8 plates of lead (each 5mm thick). Rejection of the background protons was performed at an efficiency of ∼2000 using the shower imaging capability with high granulation. The observed electron flux around a few 10 GeV is consistent with the recent results reported by the HEAT group. Comparing the flux with theoretical expectations from a diffusion model, the best fit is obtained for the model of a diffusion coefficient of 2 × 10 28 ( E/GeV ) 0.3 cm 2 /sec for the SN rate of once per 30 years in the Galaxy.