Experimental Evidence of the Directional Components of Cosmic Rays

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Abstract
It is possible to resolve the diurnal variation into two components. The first of these has its maximum at 18h and corresponds to the particle wind predicted in the theory by Alfvén (1954). The amplitude ought to be constant both as a function of geomagnetic activity and as a function of time. The second component has its maximum at 12h. It represents the sum of the various kinds of radial particle flow, and it ought to display variations indirectly related to geomagnetic activity. A search for experimental evidence of these components is made possible through the determination of the incidental directions of the primary particles by Brunberg (1953) and Brunberg and Dattner (1953). An analysis of C.R. measurements from Stockholm, Nagoya, and Huancayo seems to confirm the two components and their expected properties. A very doubtful amplitude change of the 18h-component during major magnetic storms is not at variance with theory. The Stockholm measurements were treated by Sandström (1955) as to geomagnetic effects, those from Nagoya and Huancayo by Sekido and Kodama (1952). A seasonal phase shift reported by the latter for geomagnetically quiet days is compared to measurements in Stockholm. If it exists at all the reported phase shift is evidently due to local effects. Other secular or seasonal phase shifts (Elliot and Thambyaphillai 1953) have not been treated in the present study, as the data did not provide any example of these effects. Several points are open to discussion because of the data's being collected with instruments of widely different properties. Directional counter telescopes offer the most valuable results, if they are designed for a comparatively small aperture and measure in at least two directions. DOI: 10.1111/j.2153-3490.1956.tb01193.x
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