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Long-term variations of vector and tensor anisotropies of cosmic rays

P.Y. Gololobov, G. Krymsky, P. Krivoshapkin

in 35th International Cosmic Ray Conference

Contribution: pdf


On the basis of data of Nagoya multi-directional muon telescope the long-term variations of vector and tensor anisotropies of cosmic rays that was registered in the period 1971-2015 are investigated. Decomposition of observed diurnal anisotropy into vector and tensor components is held using the method of receiving vectors. It is shown, that: 1. the amplitude of vector anisotropy reveals 11-year variations and the phase - 22-year, which is influenced by the 11-year solar activity cycle; 2. the antisymmetric diurnal component of tensor anisotropy experiences sustainable annual oscillations along the hour line 9-21 of local time, and the amplitude of which manifests 11-year variations and at the solar maxima reaches the value ~0.1%; 3. the semidiurnal component of tensor anisotropy undergoes annual and semiannual oscillations with amplitude ~0.1%. The amplitude and phase of this component reveals 11- and 22-year variations, respectively.
It is shown that the obtained average characteristics of tensor anisotropy can be described within the frameworks of the models of cosmic ray screening by sectoral interplanetary magnetic field and the shear flow of solar wind. The reasons for the appearance of 11- and 22-year variations in the tensor anisotropy is discussed. The origin of annual and semiannual variations of tensor anisotropy is due to the shift of interplanetary magnetic field to the south of the solar equatior and non-coincidence of the axes of rotation of the Earth and the Sun.