Characteristics of Forbush decreases in cosmic ray intensity observed underground

Abstract

Characteristics of Forbush decreases in cosmic ray intensity recorded underground at 60 m.w.e. during November 1960 and July 1961 are described. These decreases are compared with those recorded during the same period at sea level, as well as with those recorded at other underground stations. It is shown that, following the decreases of November 1960, large anisotropies existed in primary cosmic ray intensity which could be detected even by monitors situated deep underground. The observed decreases are compared with the predictions of different theories that have been proposed to account for Forbush decreases.