Observations of solar flare radiation and modulation effects at balloon altitudes, July 1959

Abstract

Observations of cosmic-ray time variations in the stratosphere were obtained over Berkeley, Calif. (USA), and Lindau/Harz (Germany) during the period of outstanding solar activity in July 1959. Whereas over Berkeley (geomagnetic latitude 44 deg N) only modulation of cosmic radiation by solar- controlled processes was observed, additional radiation accelerated in the vicinity of the sun (approximately 46% above normal) was observed over Lindau (geomagnetic latitude 52 deg N) on July 15. On the assumption that the excess radiation consisted almost entirely of protons, its energy spectrum had the form N(E)dE approximately E-4 dE and extended up to 400 Mev. According to conventional geomagnetic theory, individual protons of these energies are normally forbidden at geomagnetic latitude 52 deg N. Their presence over Lindau on July 15 indicates that they were admitted by some mechanism which temporarily lowers the cutoff rigidity at this latitude during a magnetic storm. There is some indication of further examples of excess radiation over Lindau at atmospheric depths down to 30 mm Hg on July 13, 21, 23, and 31.