Onsets and Release Times in Solar Particle Events

Abstract

The time at which solar energetic particles (SEPs) are first released into interplanetary space, and its relation to CMEs and various photon emissions, are important clues to the site and nature of the SEP acceleration mechanism [1- 5,7,8,10,11]. We examine velocity dispersion among onsets in electrons and ions from Wind, ACE, and IMPB, as well as available neutron monitors, to determine the solar release time. We present results for two large impulsive events (1 May 2000 and 14 April 2001) and three western ground level events (GLEs; 6 November 1997, 6 May 1998, and 15 April 2001). In the impulsive events, the particle release coincides with hard x-ray emission. But the large GLEs show delayed release with respect to 1-ray emission, consistent with acceleration by the CME-driven shock.

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