Solar protons and α particles from the September 3, 1960, flares

Abstract

The solar proton differential energy spectra have been measured in emulsions during four flights in the 48-hour interval following the class 3+ solar flare at 0110 UT on September 3,1960. During these times the spectra can be expressed as d N / d E = c o n s t E - 8 where the constant is a decreasing function of time. The cutoff energy imposed by the earth's magnetic field at Minneapolis, Minnesota, is not sharp even before the sudden commencement of the magnetic storm. During the magnetic storm the cutoff energy is lowered. Solar α particles are observed with an abundance of 3 to 7 per cent of the solar protons of the same rigidity. This abundance ratio is 3 per cent before the magnetic storms and becomes higher during the times of the storms.