Balloon measurement of solar cosmic rays at Fort Churchill, Canada, during July 1959

Balloon measurements, obtained over Fort Churchill, Canada, of solar cosmic ray intensity during July 1959 are reported. The intensities observed on July 11, 12, and 18 were many times as great as those observed simultaneously at Minneapolis. In particular, the excess Geiger counter rate at Fort Churchill was 100±25 times as great as the corresponding rate observed at Minneapolis during a small influx of radiation which occurred at 0730 UT on July 11 (before the magnetic storm that began at 1620 UT July 11). Measurements of the dependence of excess rate on atmospheric depth indicate that the energy spectrum of the solar cosmic rays did not change significantly over a period of 10 days.