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Relativistic Proton Production During the 2000 July 14 Solar Event: The Case for Multiple Source Mechanisms


Bombardieri, DJ and Duldig, ML and Michael, KJ and Humble, JE, Relativistic Proton Production During the 2000 July 14 Solar Event: The Case for Multiple Source Mechanisms, The Astrophysical Journal, 644, (1) pp. 565-574. ISSN 0004-637X (2006) [Refereed Article]

DOI: doi:10.1086/501519


Protons accelerated to relativistic energies by transient solar and interplanetary phenomena caused a ground-level cosmic-ray enhancement on 2000 July 14, Bastille Day. Near-Earth spacecraft measured the proton flux directly, and ground-based observatories measured the secondary responses to higher energy protons. We have modeled the arrival of these relativistic protons at Earth using a technique that deduces the spectrum, arrival direction, and anisotropy of the high-energy protons that produce increased responses in neutron monitors. To investigate the acceleration processes involved we have employed theoretical shock and stochastic acceleration spectral forms in our fits to spacecraft and neutron monitor data. During the rising phase of the event (10:45 and 10:50 UT) we find that the spectrum between 140 MeV and 4 GeV is best fitted by a shock acceleration spectrum. In contrast, the spectrum at the peak (10:55 and 11:00 UT) and in the declining phase (11:40 UT) is best fitted with a stochastic acceleration spectrum. We propose that at least two acceleration processes were responsible for the production of relativistic protons during the Bastille Day solar event: (1) protons were accelerated to relativistic energies by a shock, presumably a coronal mass ejection (CME); and (2) protons were also accelerated to relativistic energies by stochastic processes initiated by magnetohydrodynamic (MHD) turbulence. © 2006. The American Astronomical Society. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:High energy astrophysics and galactic cosmic rays
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Bombardieri, DJ (Dr Daniel Bombardieri)
UTAS Author:Duldig, ML (Dr Marc Duldig)
UTAS Author:Michael, KJ (Dr Kelvin Michael)
UTAS Author:Humble, JE (Dr John Humble)
ID Code:39807
Year Published:2006
Web of Science® Times Cited:31
Deposited By:Physics
Deposited On:2006-08-01
Last Modified:2011-09-29

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