Energy dependence of the rigidity spectrum of nergy Forbush d orbush decrease of galactic crease co cosmic ray intensity

摘要

We show that rigidity spectrum of Forbush decrease (Fd) of the galactic c cosmic ray (GCR) intensity in osmic September 9 9-23, 2005 has a clear dependence on the energy. We calculated rigidity spectrum of the Fd based on the data of the neutron monitors and Nagoya muon telescope channels divided in three groups according to their cut o off rigidities rigidities. We find . that temporal changes of the rigidity spectrum exponent γ are approximately similar for all cut off rigidity groups groups, but values of , γ are the larger the higher are cut off rigidities. We conclude that r rigidity spectrum igidity of Fd is hard fo for lower energy range and is soft for the higher energy range. We believe that an energy dependence of the power law rigidity spectrum of Fd is observed o owing to the preferential convection ing convection-diffusion mechanism of Fd in September 9 9-23, 2005. It is a reflecti reflection of role of the exponent on γ of the power spectral density (PSD) of the inte interpl pla- anetary magnetic field (IMF) in formation of the d netary dependence of the amplitudes of Fd on rigidity of GCR particles, pendence meaning a manifestation of the role of v in creation of the cha character of the rigidity spectrum. The exponent racter v is grea great- ter for high frequency region of the IMF turbulence (responsible for scattering of low rigidity particles of GCR), than sponsible for low frequency region of the IMF turbulence (being responsible for scattering of higher rigidity particles). Based on the distribution of average turbulence energy among the IMFs components w we challenge to estimate an existence istence of slab/2D structure of solar wind turbulence during the Fd in September 9 9-23, 2005.