The dramatic ground-level enhancement of solar cosmic rays on February 23, 1956, as inferred from the neutron monitor data

摘要

The enhancement of solar cosmic rays (SCRs) in 1956 was the largest proton event ever observed on the Earth; however, information about this event is insufficient. The paper provides a detailed analysis of the situation in the Sun and near-Earth space before, during, and after the event. The data from 14 neutron monitors operated in 1956 have been used to simulate the behavior of SCRs on February 23. Variations in the characteristics of the cosmic ray energy spectrum and anisotropy, as well as the differential and integral proton fluxes, have been determined and analyzed. It is shown that the first particles arrived at the Earth in the form of an intense, but very narrow, beam.