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CME-geometry and cosmic-ray anisotropy observed by a prototype muon detector network


Munakata, K and Kuwabara, T and Bieber, JW and Evenson, P and Pyle, R and Yasue, S and Kato, C and Fujii, Z and Duldig, ML and Humble, JE and Silva, MR and Trivedi, NB and Gonzalez, WD and Schuch, NJ, CME-geometry and cosmic-ray anisotropy observed by a prototype muon detector network, Advances in Space Research, 36, (12) pp. 2357-2362. ISSN 0273-1177 (2005) [Refereed Article]

DOI: doi:10.1016/j.asr.2003.05.064


We analyze the cosmic-ray anisotropy observed by a prototype network of muon detectors during geomagnetic storms associated with coronal mass ejections (CMEs). The network currently consists of multidirectional surface muon detectors at Nagoya (Japan) and Hobart (Australia), together with a prototype detector at São Martinho (Brazil) which has been in operation since March, 2001. In this report, we analyze the anisotropy recorded in both the muon detector and neutron monitor (the Spaceship Earth) networks and find significant enhancements of cosmic-ray anisotropy during geomagnetic storms. Following the analysis by Bieber and Evenson [Bieber, J.W., Evenson, P. CME geometry in relation to cosmic ray anisotropy. Geophys. Res. Lett. 25 (1998) 2955-2958] for the neutron monitor data at ∼10 GeV, we also derive cosmic-ray density gradients from muon data at higher-energy (∼50 GeV), possibly reflecting the larger-scale geometry of CMEs causing geomagnetic storms. We particularly find in some events the anisotropy enhancement clearly starting prior to the storm onset in both the muon and neutron data. This is the first result of the CME-geometry derived from simultaneous observations of the anisotropy with networks of multidirectional muon detectors and neutron monitors. © 2003 COSPAR. Published by Elsevier Ltd. 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:Humble, JE (Dr John Humble)
ID Code:36453
Year Published:2005
Web of Science® Times Cited:9
Deposited By:Physics
Deposited On:2005-08-01
Last Modified:2006-03-29

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