Experiments on Cosmic Rays in High-Flying Aircraft

Abstract

A BRIEF announcement has been issued by Dr. Gilbert Grosvenor and Dr. W. F. G. Swann in a News Bulletin of the National Geographic Society of Washington of some experiments on the origin of the meson component of the cosmic rays. The National Geographic Society, the Bartol Foundation and the U.S. Army co-operated in the experiments, which were made in a series of flights in a B29 aircraft at places, ranging from Northern Chile to Southern Canada, from the magnetic equator up to mag. lat. 48° N. and at altitudes up to 33,000 ft. The apparatus consisted of a number of coincidence counters arranged to record penetrating particles of which the direction of motion was in or near the vertical. The soft component (electrons and photons) was prevented from reaching the counters by a sufficient thickness of lead shielding. At 33,000 ft. the observed intensity of the mesons, using this particular experimental arrangement, was observed to increase by 33 per cent in going from mag. lat. 0° to mag. lat. 48°, and 50 per cent at 25,000 ft. The absolute change in intensity with latitude, in contrast with the above values of the relative changes, was greater at the higher altitude than at the lower.