Proton spectra of the four remarkable GLE in the 22nd solar cycle

The proton spectra of several large solar particle events in the 22nd solar cycle (namely for the enhancements on 29 September 1989, 19 October 1989, 24 May 1990 and 15 June 1991) were obtained within the wide energy range directly by experimental data without any advance model. The data from spacecraft measurements and the world network of neutron monitors have been used to analyse these events. All the obtained spectra indicate a similar behaviour in the low energy range but differ at high energies > 1 GeV. The proposed method allows us to define the times of the maximum increase depending on the particle energy. The time-energy dependencies together with the proton flux profiles at different energies and the obtained spectra might be used as a predictor for estimation of the radiation dose in the maximum of the event, as well as its behaviour. Copyright (C) 1996 Elsevier Science Ltd