Cosmic rays near the Earth corresponds nuclei flow of different elements with near-relativistic and relativistic velocities. Nuclear CR spectrum is steep-grade that is why about 92% of the flow consists of protons. Remaining part forms from alfa-particles and other nuclei. There are hard gamma-quantum, electrons and neutrinos also persisting.

Supernovas are considered the main source of CR. This main part of CR is called galactic cosmic rays (GCR). A part of CR appears from the Sun as a result of strong solar flares. The part is called solar cosmic rays (SCR). GCR and SCR compose primary cosmic radiation.

To be able to get to the surface of the Earth, cosmic rays take through the layer of atmospheric air equivalent to almost 15 nuclear track-lengths. As a result of nuclear cascade in the atmosphere, radiation that consists of elementary particles, part of which are not component of primary CR, is generated on the surface of the Earth. The main components of secondary CR are electron-photon, mu-meson and neutron.

There are two main areas of research in CR physics:

  • nuclear-physics (physics of elementary particles and nuclear interactions);
  • astrophysics (answering the questions about sources and variations (changes of intensity) of CR).

Astrophysics of CR is an area that is found at the joint of CR physics, astrophysics, geo- and heliophysics, physics of cosmic plasma. CR are high-sensitive to electromagnetic conditions in cosmic space because CR corresponds flow of charged particles. Energetic spectrum and nuclear composition of CR are not constant in time and space. CR flow in interplanetary space is, strictly speaking, not isotropic. Persistence of spatial anisotropy at the Earth revolution leads to twenty-four hour variations of CR. Intensity of CR is exposed to great influence of solar activity (SA). Significant variations of CR intensity, especially at low energies, take place in the periods of solar flares and magnetic storms. CR intensity on the Earth surface is under the influence of solar processes and processes in interplanetary space and also in Earth magnetosphere and atmosphere. Variations of intensity in CR physics are separated depending on variation source: interplanetary, magnetospheric and atmospheric. Interplanetary variations include 11-year and 27-day variations, Forbush-effects, solar CR and also variations provoked by solar plasma flows (solar wind), emissions of coronal mass and other solar processes.

Sporadical solar phenomena account for foundation of solar CR with intensity increase in several times (for example, in 29th of September 1989 increasing of intensity observed in Novosibirsk at the sea level was equal to 183,9%), lead to geomagnetic storms, malfunction of radio communication, failures of technical systems, deterioration of health of chronic patients. In addition to solution of problems of fundamental science, research of CR variations provides solution of tasks of interplanetary processes diagnostic, possibility of prediction of SA and sporadical solar phenomena.

Results of observations of CR intensity on the Earth surface can be found on web-sites of CR stations world network (45 currently working stations included). Data observed gathered in the World Data Center (WDC) and available to scientific community.

* Read about cosmic rays on Astronet