Measurements of cosmic-ray electrons in the energy range 4 MeV to 6 BeV at 2 g/cm2 atmospheric depth at Ft. Churchill

Abstract

In this paper we extend our recent measurements on electrons in the energy range 70–2 400 MeV to energies from 4 MeV to 6 000 MeV. These new measurements have been made using two separate telescopes which are sensitive to electrons in different but overlapping energy ranges. Detailed ascent curves are available for electrons from 4 MeV to [Formula: see text], permitting the derivation of a secondary electron production function at the top of the atmosphere. This production function is compared with the theoretical calculations of Perola and Scarsi (1966) and Verma (1967) appropriate to energies >50 MeV and the calculations of Beedle (1966) relating to the production of low-energy electrons by the knock-on process and by Compton scattering of photons.From our studies we derive the total electron spectrum existing at 2.3 g/cm² atmospheric depth at Ft. Churchill in 1966. Subtracting from this our experimentally derived secondary production of electrons, we are able to determine the spectrum of extraterrestrial electrons from [Formula: see text] to >6 BeV. This spectrum is compared with other observations, and the galactic nature of the particles is discussed. The variability of these particles with time is investigated. Some observations regarding the creation of these electrons in the galaxy are also made.