| Summary: | Using a newly developed ionization chamber, which transmits its information by radio, simultaneous balloon flights were made from widely separated stations in the summer of 1951. Bismarck, North Dakota (geomagnetic latitude, λm, 56°N) was used as a base station. Four flights were made from shipboard going north from Boston and five were made from Thule, Greenland (λm=88°N), simultaneous with those at Bismarck. In all, 28 successful flights were made by the two expeditions. In seeking to determine the geomagnetic effects on the low energy primaries, considerable information was gathered on the radiation that fluctuates from day to day. The following are the chief experimental findings together with some of the conclusions that may be drawn. (1) The fluctuations in the primary radiation at 90 000 feet were as much as 10 percent in a few days. (2) These were simultaneous (except as noted in the text) and very close to the same amount at the two stations. (3) The magnitude of the fluctuations at high altitudes was considerably larger than the geomagnetic effect between Bismarck and Thule. (4) The radiation that fluctuated contained both high (> 15 Bev/c) momentum and low (down to 1.5 Bev/c) momentum particles. (5) There was a good correlation between the fluctuations in the radiation at high altitudes and the fluctuations in the neutron and meson components at ground level. (6) The fact that no particles fluctuated at Thule that did not also fluctuate at Bismarck leads us to conclude that there are few, if any, low energy particles coming in at Thule that are not also present at Bismarck, otherwise they too would be expected to vary. (7) From the manner in which the fluctuating radiation is absorbed in the atmosphere, it is concluded that the fluctuations cannot be due to heavy primaries alone. Rather it appears that the particles that fluctuate are of the same nature as the other incoming particles but have somewhat less energy per particle. (8) Varying magnetic fields of the geomagnetic axially symmetrical ...
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