Authors: C.M.S. Cohen
Affiliation: California Institute of Technology
It has been clear for a long time that solar energetic particles (SEPs) were accelerated by flares as well as CME-driven shocks. A decade ago it was widely believed that the two acceleration mechanisms produced mutually exclusive results: ‘impulsive’ vs. ‘gradual’ SEP events. Today many are questioning this belief in part due to improved composition measurements being made of SEPs at a few MeV/nucleon and above by instruments on ACE and Wind. I will briefly review some of these measurements and then discuss the ideas regarding the roles of flare and shock acceleration currently being discussed in the SEP community in an effort to understand these results as well as future measurements that could potentially provide further insights.