Unseen GLEs (Ground Level Events)
Abstract
Over the last seventy years, solar energetic particle (SEP) ground level events (GLEs) have been observed by ground-based neutron monitors and muon telescopes at a rate of slightly more than one per year. Ground-based detectors only measure secondary particles, and matching their observations with SEP in-situ measurements from spacecraft has been difficult. Now, the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument provides in-situ measurements that also include composition and pitch-angle distribution and bridge the energy between long-term SEP monitors in space (e.g. ACE and GOES) and the ground-based observations. The PAMELA data show that there are a few SEP events (e.g. 23 Jan 2012) where PAMELA sees high-energy (> 1 GeV) particles, yet these are not registered as GLEs. We will present evidence that the anisotropic distribution of these SEPs may miss the global network of neutron monitors.
- Publication:
-
AAS/AGU Triennial Earth-Sun Summit
- Pub Date:
- April 2015
- Bibcode:
- 2015TESS....120503C