The Relative Intensity of Cosmic Rays at Sea Level at Geomagnetic Latitudes 56.8 and 83.0

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Abstract
During the summer of 1950 two cosmic-ray counter telescopes were exchanged between Ottawa (geomagnetic latitude 56.8°N) and Resolute (geomagnetic latitude 83.0°N) in such a way that an accurate comparison of vertical intensities could be made. The telescopes were operated under almost identical conditions for about three weeks; then they were exchanged, the Ottawa telescope being flown to Resolute and the equipment there returned to Ottawa. Corrections were made for barometer and differences in altitude by reducing all counting rates to that at 1000 mb pressure using known barometer coefficients. Corrections were made for differences in the atmospheric temperature by integrating numerically through the mean atmosphere at each station to get the probability of meson decay between production levels and the 1000-mb layer. When all corrections were made there remained a difference in intensity of 1.76±0.75 percent. No difference would be expected with the absorbers used (14½ inches of lead) at latitudes so high above the "knee." Arguments are presented to show that the difference is probably due to mesons produced by a group of field sensitive primaries and scattered into the telescope. This group of primaries could come from directions with large zenith angles, which would be allowed at Resolute but excluded at Ottawa.