Accession Number : AD0775862

Title :   Anomalous Cosmic-Ray Anisotropy and Unidirectional Interplanetary Magnetic Field during 1954,


Personal Author(s) : Antonucci,Ester

Report Date : SEP 1973

Pagination or Media Count : 20

Abstract : Observations of the interplanetary magnetic field during solar minimum lead to the following important conclusions for cosmic ray modulation: (a) the interplanetary magnetic field does not show any sector structure for a few solar rotations, i.e. the field has polarity away from the sun during this interval, (b) cosmic ray diffusion in the interplanetary medium is essentially anisotropic for rigidity of the order of 10 GV (K parallel/K perpendicular approximately 0.01 ratio of diffusion coefficients calculated from the magnetic-field power spectra by Jokipii and Coleman). If diffusion occurs essentially along the magnetic field lines, the cosmic ray density U(r, T) is a symmetric function of the heliolatitude lambda with a minimum in the equatorial plane: U(r, T, lambda) proportional to a exp(-b cosine squared (lambda)). Therefore a cosmic ray density gradient across the solar equatorial plane exists and it depends on the size of the modulation region. (Modified author abstract)

Descriptors :   *Cosmic rays, Anisotropy, Intensity, Diurnal variations, Magnetic fields, Modulation

Subject Categories : Astrophysics

Distribution Statement : APPROVED FOR PUBLIC RELEASE