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North-south anisotropy of galactic cosmic rays observed with the Global Muon Detector Network (GMDN)


Munakata, K and Kozai, M and Kato, C and Kuwabara, T and Rockenbach, M and Dal Lago, A and Schuch, NJ and Al Jassar, HK and Sharma, MM and Duldig, ML and Humble, JE and Bieber, JW and Evenson, P and Sabbah, I and Tokumaru, M, North-south anisotropy of galactic cosmic rays observed with the Global Muon Detector Network (GMDN), Proceedings of Science, 30 July - 06 August, The Hague, Netherlands, pp. 1-7. ISSN 1824-8039 (2015) [Non Refereed Conference Paper]

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We analyze the north-south anisotropy (NSA) of galactic cosmic rays observed with the GMDN on an hourly basis and compare with the anisotropy derived from the GG-component of a large multidirectional muon detector at Nagoya, Japan. The NSA is a component of the three dimensional anisotropy vector parallel to the Earth’s rotation axis. We find a significant seasonal variation of the NSA from the GG-component indicating the influence of the anisotropy component in the ecliptic plane to the NSA. We calculate the average and standard deviation of daily mean NSAs in the "toward" (T) and "away" (A) IMF sectors separately in each Carrington Rotation between December 1993 and November 2014. It is confirmed that the temporal variations of the NSA observed with the GMDN and GG-component are consistent with each other, as reported earlier. We find the T-A separation between average NSAs in T and A sectors shows a long-term variation with minima (maxima) around the solar activity minima (maxima). The standard deviation in each rotation also shows a similar long-term variation, keeping the ratio of T-A separation to the standard deviation roughly constant thorough out an entire period of analysis. We discuss this in relation with the "success rate" which is introduced as a parameter indicating to what extent we can infer the IMF sector polarity from the sign of the observed NSA.

Item Details

Item Type:Non Refereed Conference Paper
Keywords:cosmic rays, modulation, north-south anisotropy
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:Duldig, ML (Dr Marc Duldig)
UTAS Author:Humble, JE (Dr John Humble)
ID Code:110300
Year Published:2015
Deposited By:Mathematics and Physics
Deposited On:2016-07-23
Last Modified:2016-08-05

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