Cosmic Rays in the Dipole Geomagnetic Field

The foundation and development of the theory of charged energetic particles moving in the magnetic field of the earth came about through the need to explain some geophysical phenomena. These investigations were initiated by C. Störmer (1907), who by researching charged energetic particles moving in the earth's magnetic field, tried to understand the nature of the polar aurora phenomenon. The earth's magnetic field may be presented for a first approximation as a field produced by a dipole with a moment M_E = 8.1×10²⁵ Gs.cm³ inclined at 11.5° to the earth's rotation axis and shifted by 342 km relative to the earth's center (according to the magnetic survey of 1944). Stórmer (1907, 1931, M1955) based his theory on the dipole approximation of the earth's magnetic field, which describes the main part of the real geomagnetic field. For a long time Stórmer's theory was also applied to the investigation of the behavior of charged particles of CRs in the earth's magnetic field. Until now this theory has not lost its interest because many effects of CRs in the geomagnetic field (latitude and East—West geomagnetic effects, cutoff rigidities, penumbra, formation of radiation belts, and others) are the same as in a real field and the difference is only quantitative.