The solar cosmic-ray outburst of May 4, 1960

Abstract

Low‐energy nucleonic cosmic‐ray data from stations at Lincoln, Mt. Washington, Sulfur Mountain, and Deep River were studied with regard to onset times, time and magnitude of maximum increase, and decay characteristics. The decay behavior underwent a definite transition that is clearly related to the termination of the optical flare. The first part of the decay is clearly exponential, with a time constant in the neighborhood of 17 minutes, whereas the latter part is not distinctly established either as exponential (with a possible time constant of 78 minutes) or as following a t−1.5 law. Ordinary impact zones do not seem to fit the pattern of increases observed at various stations in the northern hemisphere.

Relativistic solar cosmic rays

“…The diffusion of these particles through a sun and the fact that in many events the spatial distribution homogeneous, isotropic, three dimensional medium can be becomes almost isotropic during the decay phase, it is gener-described by the following equation: 1 (Figure 32), which is close to the value deduced by Krimigis [1965] for energetic particles. A major problem concerning this model is that at long times (t >> tmax) the decay of the intensity is expected to be proportional to t -a/•'-•, which is in disagreement with the observed exponential decay [see, e.g., Webber, 1963;Anderson et al, 1960]. In fact, in some events the exponential decay sets in immediately after tm (Figure 33).…”

Time Variation of Cosmic Ray Intensity in the Antarctic Region II. Unusual Increase

“…The type of neutron monitor at Syowa Base is not identical with the standard type, but cosmic ray neutrons measured by it show time variations similar to those by the standard type (Fukushima, Kitamura and Kodama, 1961 is that the decay time is shortest (Anderson et al, 1960). The fluctuation of the enhanced intensities still remains among the stations except Churchill and Ellsworth and at least it is larger than in the other events.…”