Säm Krucker, Robert P. Lin Space Science Laboratory, University of California, Berkeley, CA
The 3-D Plasma and Energetic Particles experiment on the WIND
spacecraft was designed to provide high sensitivity measurements of
both suprathermal ions and electrons down to solar wind energies. A
statistical survey of 52 solar proton events has been investigated.
For all proton events, a temporally related electron event is
observed. The presented results focus on the properties of protons
released near the Sun which show a velocity dispersion when detected at
1 AU. The analysis of the spectral, temporal, and spatial observations
reveal the following main results:
1) Dispersive protons show a low energy cut off between about 0.1 and 1 MeV.
2) There are two classes of proton events: For one class (70% of the events), the first arriving protons are traveling almost scatterfree as indicated by the derived path lengths between 1.1 and 1.3 AU, whereas the events of the second class show significantly larger path lengths around 2 AU.
3) Relative to the electron release time at the Sun, the almost scatterfree traveling protons of the first class of events are release delayed by 0.5 to 2 hours. For the events of the second class, protons and electrons seemed to be released simultaneously within the accuracy of 20 minutes.