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A “loss cone” precursor of an approaching shock observed by a cosmic ray muon hodoscope on October 28, 2003
Author(s) -
Munakata K.,
Kuwabara T.,
Yasue S.,
Kato C.,
Akahane S.,
Koyama M.,
Ohashi Y.,
Okada A.,
Aoki T.,
Mitsui K.,
Kojima H.,
Bieber J. W.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021469
Subject(s) - hodoscope , physics , cosmic ray , shock (circulatory) , muon , rigidity (electromagnetism) , nuclear physics , anisotropy , heliosphere , earth's magnetic field , magnetic field , computational physics , solar wind , plasma , optics , medicine , quantum mechanics
We analyze a loss cone anisotropy observed by a ground‐based muon hodoscope at Mt. Norikura in Japan for 7 hours preceding the arrival of an interplanetary shock at Earth on October 28, 2003. Best fitting a model to the observed anisotropy suggests that the loss cone in this event has a rather broad pitch‐angle distribution with a half‐width about 50° from the IMF. According to numerical simulations of high‐energy particle transport across the shock, this implies that the shock is a “quasi‐parallel” shock in which the angle between the magnetic field and the shock normal is only 6°. It is also suggested that the lead‐time of this precursor is almost independent of the rigidity and about 4 hour at both 30 GV for muon detectors and 10 GV for neutron monitors.