Origin of the solar-magnetic-cycle dependent semiannual variation in galactic cosmic-ray flux

Journal Article · Wed Nov 01 04:00:00 EST 1978 · Geophys. Res. Lett.; (United States)

DOI:https://doi.org/10.1029/GL005i011p00969· OSTI ID:6589784

Levy, E

In this paper we point out that the general dipole-like symmetry of the interplanetary magnetic field produces a heliospheric latitude variation in the density of modulated galactic cosmic rays. This density variation gives the observed semiannual variation in the galactic cosmic-ray flux observed at Earth, which changes phase with the sign of the solar magnetic field.We derive an explicit expression for the symmetric cosmic-ray density gradient in the direction perpendicular to the solar equatorial plane and use it to derive a value for the cosmic-ray diffusion coefficient perpendicular to the average interplentary magnetic field.

• Research Organization: Department of Planetary Sciences and Lunar and Planetary Laboratory University of Arizona, Tucson, Arizona 85721
• OSTI ID: 6589784
• Journal Information: Geophys. Res. Lett.; (United States), Journal Name: Geophys. Res. Lett.; (United States) Vol. 5:11; ISSN GPRLA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANNUAL VARIATIONS
COSMIC RADIATION
COSMIC RAY FLUX
DIFFUSION
GEOGRAPHICAL VARIATIONS
INTERPLANETARY MAGNETIC FIELDS
IONIZING RADIATIONS
LATITUDE EFFECT
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MODULATION
PRIMARY COSMIC RADIATION
RADIATION FLUX
RADIATIONS
VARIATIONS