Primary cosmic ray electrons below 600 MeV

Abstract

The primary cosmic ray electron flux between 25 MeV and 600 MeV has been measured with a system composed of a Cerenkov telescope and a scintillation detector, separated by lead absorber. A modified detector has investigated the primary electron differential energy spectrum. Results are presented from balloon nights made from both Kiruna, Northern Sweden and Cardington, England, between 1964 and 1966. The flights from England specifically investigated the atmospheric secondary electron component and these measurements are compared with recent theoretical calculations. The Kiruna observations are corrected for atmospheric secondary electrons using both the theoretical and experimental data. The results are well represented by a power law spectrum of the form: dJ dE =12 +1·5 −3·2 E −0.6±0.2 electron/m 2. sec. sr. Mev between 25 MeV and 500 MeV. A comparison is made with the results of other investigators. The origin of low energy primary electrons is discussed and emphasis is placed on the galactic “secondary” source in the energy range under observation.