Unidirectional Measurements of the Cosmic-Ray Latitude Effect

Abstract

Cosmic-ray intensities in the vertical direction, and in two inclined directions, 45\ifmmode^\circ\else\textdegree\fi{} eastwards and 45\ifmmode^\circ\else\textdegree\fi{} westwards from the zenith, have been recorded as a function of latitude. The apparatus, embodying several coincidence counter trains, was arranged for unattended operation and automatic recording. It has made several voyages between New York and southern Chile through the Panama Canal on ships of the Grace Line. A latitude effect of 12 percent was found in the eastern direction compared with 4 percent in the western direction. Two values for the vertical latitude effect have been found, one about 12 percent and the other about 20 percent, and it is uncertain in the present measurements which one is correct. The intensity in the vertical and western directions is strongly influenced by local anomalies in the earth's magnetic field, whereas eastern intensities agree more closely with the distribution expected if the earth's field were that of a dipole. Shower intensities, recorded on one voyage, showed less of a latitude effect than vertical rays.