Distribution Of Cosmic Ray Intensity Research Articles

Phenomena of Absorption of Soft and Hard Components of Space Rays in the Atmosphere in Yerevan Conditions

The article examines the angular distribution of cosmic ray intensity and identifies the triads using two different empirical formulas for their distribution. The total absorption coefficient of soft and hard components was measured.

Solar semidiurnal anisotropy of galactic cosmic ray intensity observed by the two‐hemisphere network of surface‐level muon telescopes

Observations made by the two‐hemisphere network of surface‐level, multidirectional muon telescopes at Hobart (Tasmania, Australia) and Nagoya (Aichi, Japan) are used to examine the origin of the solar semidiurnal variation in cosmic ray intensity. The network allows us to precisely determine the asymmetry of the variation across both hemispheres. It is shown that the variation is consistent with the north–south (NS) symmetric distribution of cosmic ray intensity in space. The phase of the space harmonic vector responsible for the variation is consistent with both the second‐order anisotropy expected from a bidirectional latitudinal density gradient (type I) and also one arising from pitch angle scattering (type II). The network also observed a purely NS antisymmetric, antisidereal diurnal variation with the maximum phases differing by 12 hours between the two hemispheres. This is consistent with an antisidereal diurnal variation arising from annual modulation of the solar diurnal variation produced by a second‐order anisotropy. The phase of the space harmonic vector responsible for the antisidereal diurnal variation is consistent with the phases predicted from both type I and type II anisotropies. It is shown, however, that the ratio of the amplitude of the space harmonic vector of the antisidereal diurnal variation to that of the solar semidiurnal variations is consistent with the type II anisotropy but not with the type I anisotropy. This result implies that the solar semidiurnal variation and the antisidereal diurnal variation observed during the period 1992–1995 mainly arise from the type II anisotropy and cannot be explained solely as arising from the type I anisotropy.

Semidiurnal Anisotropy of Galactic Cosmic Ray Intensity

The semidiurnal variation of galactic cosmic ray intensity is investigated using data from mainly high counting rate neutron and meson monitors during 1964–1968. It is shown that in order to explain the observed semidiurnal variation it is necessary that an anisotropy of cosmic ray intensity be present in interplanetary space. The energy spectrum and the asymptotic latitude dependence of the anisotropy are then determined. The energy spectrum has a positive exponent close to + 1 for the power law in energy. The strength of the anisotropy decreases more rapidly than cosλ with increasing asymptotic latitude λ, both cos2λ and cos3λ being acceptable. The distribution of cosmic ray intensity in the range of heliolatitudes ± 7.25° at the orbit of the earth, obtained using data from the Ottawa neutron monitor, does not support the explanation of the semidiurnal variation based on the models of Subramanian and Sarabhai or Lietti and Quenby.

Spatial distribution of cosmic ray intensity and geomagnetic theory

Abstract Data recorded in a world-wide investigation of relationships between the spatial distribution of cosmic ray intensity and the magnetic field of the earth have been compared with the predictions of geomagnetic theory. Measurements obtained with a neutron monitor in the U.S. Navy Hydrographic Office Airborne Geomagnetic Survey-Project MAGNET are well organized in terms of new calculations of vertical threshold magnetic rigidities by Quenby and Wenk, who have taken into account the effects of the dipole and non-dipole parts of the field as well as the penumbral correction. Except for the observations over one region in the North Atlantic, a plot of nucleonic intensity versus threshold rigidity reveals that all the points fall within a narrow band.

A Survey of the Cosmic-Ray Nucleonic Component along 145° East Longitude using an Airborne Monitor

MANY reports have appeared in recent years of discrepancies between the observed distribution of cosmic ray intensity over the surface of the Earth and that expected from conventional geomagnetic theory. For example, the geomagnetic equator does not fit reported positions of equatorial cosmic ray minima1 and a new cosmic ray equator must be determined by experiment. Furthermore, at intermediate latitudes direct measurements of low-rigidity cut-offs of alpha-particles and heavier nuclei frequently differ from those calculated from the Stormer theory using standard geomagnetic co-ordinates2. It appears that geomagnetic co-ordinates must be replaced by a new system of co-ordinates for the description of the Earth's effective magnetic field for cosmic rays.