Long-term variations of the Primary Cosmic-Ray Electron Component

Abstract

The intensity of primary cosmic-ray electrons has been measured from 1960 through 1966 at balloon altitude over Ft. Churchill, Manitoba. Initial measurements were made with an energy-loss vs. range counter telescope from 1960 through 1964. From 1964 through 1966 an energy-loss vs. total energy counter telescope was used. Overlapping data exist for both instruments in 1964. Our results are consistent with the absence of a solar modulation effect for electrons in the 0.25 to 1.05 BV rigidity range. The experimental errors lead to an upper limit of 60% for the possible fractional change of the electron intensity over this period.