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http://dx.doi.org/10.5140/JASS.2006.23.2.117

LOCAL TIMES OF GALACTIC COSMIC RAY INTENSITY MAXIMUM AND MINIMUM IN THE DIURNAL VARIATION  

Oh Su-Yeon (Dept. of Astronomy and Space Science, Chungnam University)
Yi Yu (Dept. of Astronomy and Space Science, Chungnam University)
Publication Information
Journal of Astronomy and Space Sciences / v.23, no.2, 2006 , pp. 117-126 More about this Journal
Abstract
The Diurnal variation of galactic cosmic ray (GCR) flux intensity observed by the ground Neutron Monitor (NM) shows a sinusoidal pattern with the amplitude of $1{\sim}2%$ of daily mean. We carried out a statistical study on tendencies of the local times of GCR intensity daily maximum aad minimum. To test the influences of the solar activity and the location (cut-off rigidity) on the distribution in the local times of maximum and minimum GCR intensity, we have examined the data of 1996 (solar minimum) and 2000 (solar maximum) at the low-latitude Haleakala (latitude: 20.72 N, cut-off rigidity: 12.91 GeV) and the high-latitude Oulu (latitude: 65.05 N, cut-off rigidity: 0.81 GeV) NM stations. The most frequent local times of the GCR intensity daily maximum and minimum come later about $2{\sim}3$ hours in the solar activity maximum year 2000 than in the solar activity minimum you 1996. Oulu NM station whose cut-off rigidity is smaller has the most frequent local times of the GCR intensity maximum and minimum later by $2{\sim}3$ hours from those of Haleakala station. This feature is more evident at the solar maximum. The phase of the daily variation in GCR is dependent upon the interplanetary magnetic field varying with the solar activity and the cut-off rigidity varying with the geographic latitude.
Keywords
galactic cosmic rays; diurnal variation; solar maximum & minimum;
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  • Reference
1 Ananth, A. G., Kudela, K, & Venkatesan, D. 1995, Solar Physics, 159, 191   DOI
2 Ananth, A. G., Venkatesan, D., & Pillai, S. 1993, Solar Physics, 143, 187
3 Bieber, J. W. & Chen, J. 1991, ApJ, 372, 301   DOI
4 Dorman, I. L. 2003, Cosmic rays in the Earth's atmosphere and underground (Dordrecht: Kluwer Academic Publishers), p.644
5 Mursula, K & Usoskin, I. 2003, Heliospheric physics and cosmic rays (Oulu: Oulu University Press), p.123