Energetic particle observations at the Helios 1 spacecraft of shocks associated with coronal mass ejections

Energetic particle data from the Helios 1 spacecraft have been used to study the particles associated with 26 coronal mass ejection (CME)/shock pairs. The particle events are divided into four classes on the basis of the relative intensities of their prompt and shock-associated components. Events in group 1 have strong prompt and shock components and are associated with energetic CMEs originating, most commonly, with central meridian flares. Group 2 events characteristically have strong prompt components and weaker shock components and are associated with western hemisphere (i.e., favorably located) flares. Group 3 consists of events with absent prompt components and strong shock components; the CMEs probably originate in disappearing filament events near central meridian. Group 4 events show no particle enhancements and are associated with slow CMEs and slow shocks.