Dynamics of energetic spectrum of solar-diurnal variations of cosmic rays in 19-24 solar activity cycles

The anisotropic angular distribution of cosmic rays (CR) in the interplanetary medium manifests itself on Earth as periodic diurnal intensity variations. Ground-based detectors of CRs have different energy sensitivity to the primary CR radiation and, therefore, the amplitude and phase recorded by them are also different. This fact makes it possible to study the energy spectrum of the variations when using a sufficient number of detectors. In this work, the results of the investigation of the energy spectrum of solar-diurnal variations of CRs obtained by a network of neutron monitors and muon telescopes are presented. The network allows measuring CRs with median energies from units to hundreds of GeV. The expected values of the amplitude and phase of the daily CR variations at the selected ground-based stations for different types of the energy spectrum are shown. The calculated data are compared with experimental data for 19-24 solar activity cycles

Cosmic ray angular distribution dynamics during Forbush decrease in 3-4 November 2021

On November 3-4, 2021, there was a coronal ejection of the solar mass into the interplanetary medium. According to direct observations of the interplanetary magnetic field and the solar wind, the ejection was accompanied by a magnetic cloud. During the event, neutron monitors of the NMDB network registered a two-stage Forbush decrease with a total amplitude of up to 15%. A preliminary analysis of the NMDB data shows that the first step was due to the cosmic ray decrease behind the shock wave front, while the second step was due to the cosmic ray anisotropy formed in the magnetic cloud. This work was undertaken to study the dynamics of the angular distribution of cosmic rays in this event. The cosmic ray distribution was determined using the global survey method developed at the ShICRA in the 1960s. The method makes it possible to use the worldwide network of neutron monitors as a single multidirectional instrument and to determine the hourly dynamics of CR distribution. It is shown that unidirectional and bidirectional anisotropies of significant amplitude are observed inside the magnetic cloud. The results obtained are discussed in the framework of modern theories of the formation of magnetic clouds. The temporal dynamics of the spatial-angular distribution of cosmic rays during the Forbush decrease on November 3–4, 2021 was determined. The presence of cosmic ray anisotropy with an amplitude comparable to the magnitude of the density decrease itself was found