Large ground level events in solar cycle 22 and some peculiarities of relativistic proton acceleration
Abstract
Some of the Ground Level Enhancements of Solar Cosmic Rays (SCR) recorded by neutron monitors during solar cycle 22 are analyzed. The events appeared in series, and their occurence rate in 1989-1991 was a factor of 4 larger than the average value (≅1/yr) for the total observation interval (since 1942). The events of Sept. 29 and Oct. 24, 1989 proved to be the more intensive. The analyzed events show no peculiarities as to the distribution of the T1/2 parameter, whereas the shape of the profile of some events is notable for a two peak structure. The later implies the possibility of a two component SCR ejection from two different sources in the solar atmosphere. For the event of Sep. 29 we have estimated the ejection rigidity spectrum of protons to be Dsolar (R) = (1-2) 1032R-2.9 Gv-1 at R>= 1 Gv. As to its proton flux, this event proved to be by 1-2 orders less intensive than the well known event of Feb. 23 1956.
- Publication:
-
Advances in Space Research
- Pub Date:
- October 1994
- DOI:
- 10.1016/0273-1177(94)90531-2
- Bibcode:
- 1994AdSpR..14j.711V
- Keywords:
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- Ground Stations;
- Radiation Measuring Instruments;
- Solar Cosmic Rays;
- Solar Cycles;
- Solar Protons;
- Angular Distribution;
- Neutron Counters;
- Nuclear Particles;
- Proton Flux Density;
- Relativistic Particles;
- X Ray Spectroscopy;
- Solar Physics