Solar proton spectrums in the events of November 12 and 15, 1960

Abstract

Freier and Webber have demonstrated that an exponential rigidity spectrum provides a good empirical fit to solar proton data over a wide range of rigidity and during widely different events. In this paper we discuss the conclusions they have drawn about the events of November 12 and 15, 1960, during which a series of rocket flights was made by the Goddard Space Flight Center. We find that for the November 12 event an exponential rigidity spectrum does not fit the observations, owing to the presence of a relatively large number of low-energy protons, and that data obtained late in the November 15 event are consistent with an exponential rigidity spectrum. We suggest that the difference in character of the spectrums observed in these two events is due to a flux of low-energy protons arriving at the earth on November 12 with the solar plasma responsible for concurrent geomagnetic disturbances. The flights made late in the November 15 event were during a geomagnetically quiet time.