Speaker
Dr
James M Ryan
(University of New Hampshire)
Description
We report the proton spectrum of two GLEs, 2001 April 15 and 2005 January 20. Using two
instruments, the Climax neutron monitor and the Milagro ground based TeV gamma-ray
telescope, we constructed the spectrum of the highest energy part of the GLE spectrum. The
many available rigidity thresholds in the Milagro instrument, coupled with the nearby Climax
NM, allows one to construct a differential spectrum above 1 GV rigidity. We find that the
impulsive, anisotropic phase of both events is systematically harder than the delayed isotropic
phase. We fit both spectra to power laws in energy with exponential roll overs. We find that
the roll over energy abruptly drops after the anisotropic phase and seems to remain roughly
constant thereafter. Because the roll over energy embodies important physics in the shock
acceleration process, this implies that if the particles in the delayed phase came directly from
the shock, the conditions changed significantly or that the original population injected by the
shock has been modified by transport effects.
Author
Dr
James M Ryan
(University of New Hampshire)
