AbstractIn this study we applied again to the outstanding solar particle event of 23 February 1956, the largest one in the entire history of observations of solar cosmic rays. Due to significant improvement of the analysis/modeling techniques and new understanding of physical processes in the solar atmosphere and interplanetary space, a possibility arises to interpret the old data in the light of modern concept of multiple particle acceleration at/near the Sun. In our new analysis the data of available then neutron monitors and muon telescopes are used. The technique of the analysis includes: (a) calculation of asymptotic cones of ground-based detectors; (b) modeling of cosmic ray detector responses at variable parameters of the flux of solar relativistic protons; (c) determination of primary solar proton parameters outside magnetosphere by comparison of computed responses with observations. Certain evidence was obtained that the flux of relativistic solar protons consisted of two distinct components: prompt and delayed ones. The prompt component with exponential energy spectrum caused a giant impulse-like increase at a number of European cosmic ray stations. The delayed component had a power-law spectrum and was a cause of gradual increase at cosmic ray stations in the North American region. A numerical simulation of the proton acceleration in the vicinity of the magnetic reconnection region brings to the proton spectrum with exponential dependence on energy. This agrees with observational data for the prompt component. It is also shown that the huge increase in ∼5000% on neutron monitors was due to the prompt component only with the exponential proton spectrum. The power-law spectrum of comparable intensity gave considerably smaller effect.
Relativistic solar protons in the ground level event of 23 February 1956: New study
Advances in Space Research ; 41 , 6 ; 926-935
2007-04-18
10 pages
Article (Journal)
Electronic Resource
English
Relativistic solar protons in the ground level event of 23 February 1956: New study
Online Contents | 2008
|Relativistic solar protons in the ground level event of 23 February 1956: New study
Online Contents | 2008
|The solar-terrestrial event of 23 February 1956
Elsevier | 2009
|The solar-terrestrial event of 23 February 1956
Online Contents | 2009
|A study of the ground level enhancement of 23 February 1956
Elsevier | 2004
|