DIFFUSIVE-SHOCK-ACCELERATED INTERPLANETARY IONS AT SEVERAL ENERGIES DURING THE SOLAR-CYCLE-21 MAXIMUM

The most intense energetic particle (mainly proton) events in the ener gy range 36-1600 keV, during the years of maximum activity of solar cy cle 21 (1978 to 1982), have been studied with regard to their spectra, temporal profiles. source location at the Sun, interplanetary plasma parameters and interplanetary magnetic field topology. In all the even ts, the particles were accelerated by the 'Diffusive Shock' accelerati on mechanism, because all the events were 'long-duration events', shoc k-associated, and their spectra fitted to a power-law energetic partic le spectrum dJ/dE similar to E-gamma with the exponent values ranging from 1.25 up to 1.94, with a mean value of 1.60 +/- 0.06. We also show that the spectral indexes gamma are related to the shock properties b y a linear expression. The solar sources were located on a wide longit udinal belt extending from 500 W up to 73 degrees E. Neither the spect ral indexes nor the shock parameters present any dependence on the sou rce location at the Sun. Finally, only one event showed the complete s et of properties that characterize the presence of a magnetic cloud as sociated with the event.