Magnetic-Cloud-Chamber Observations of Low-Energy Cosmic-Ray Electrons

The flux of cosmic-ray electrons in the energy range $45<E<\mathrm{}150\mathrm{}$ MeV has been measured at balloon altitudes over a wide range of geomagnetic latitudes. The data obtained led to the following conclusions: (1) The flux of primary electrons in the above energy range is less than 35 particles/${\mathrm{m}}^2$-sec-sr. (2) The geomagnetic cutoff rigidity at Fort Churchill, Manitoba, is less than 45 MV; this is significantly less than the cutoff expected from the earth's interval field alone.