Galactic Rotation and the Intensity of Cosmic Radiation at the Geomagnetic Equator

Abstract

The angle of deflection experienced by a primary cosmic particle moving in the plane of the geomagnetic equator is calculated for different energies and the result used to find the diurnal variation in the intensity of cosmic rays arriving vertically at the geomagnetic equator. If it is assumed that the number of primaries varies inversely as the cube of their energy, the calculation shows that there should be a diurnal variation in the vertical intensity of 0.17 percent, if all primaries are positive, with a maximum at 13 hr. 20 min. sidereal time. With a ratio of three positive to one negative primary, and the same distribution law, the amplitude of the diurnal variation should be 0.1 percent with a maximum at 12 hr. 30 min. sidereal time, while if the primary radiation as a whole is neutral (one positive particle to each negative) the amplitude should be 0.06 percent with maximum at 8 hr. 40 min. sidereal time. If the number of primaries is an exponentially decreasing function of their energy, the amplitude of the diurnal variation should be 0.24 percent with maximum at 18 hr. sidereal time, assuming all primaries are positive; if the primary radiation is neutral the amplitude should be 0.19 percent and the maximum should occur at 20 hr. 40 min. sidereal time. The expected diurnal variations for several values of the lower limiting energy are also discussed.