American Upper Air Cosmic Ray Expedition

Abstract

THE National Geographic Society, the United States Army Air Force and the Bartol Research Foundation will jointly conduct a series of four round-trip nights in a specially equipped B-29 bomber to investigate the variation with latitude and longitude of cosmic ray intensities. The flights will extend between lat. 50° N. and the magnetic equator, some 20° south of the geographic equator ; and studies will be made at altitudes of 5,000, 15,000, 25,000 and 35,000 ft. The trips will not necessarily be continuous, and parts of each flight may even be made at different levels so long as complete round trips at each of the four altitudes can be pieced together. The principal apparatus to be carried in the plane, consisting of multiple banks of Geiger counters, has been designed by Dr. W. F. G. Swann, director of the Bartol Research Foundation. The counters are so arranged that they will record only the particles which move downward vertically. It is hoped to discover the pattern of cosmic ray intensity in a cross-section of the atmosphere extending 4,800 miles northward from the magnetic equator, and reaching from sea-level more than 6½ miles high, and so learn more about the nature of the primary particles entering the atmosphere and breaking down there to form mesotrons. The investigations will be carried out under the direction of Dr. Lyman J. Briggs, chairman of the Research Committee of the National Geographic Society and formerly director of the National Bureau of Standards. The Army Air Force's co-operation in the project is under the supervision of Major-General Curtis E. Le May, deputy chief of staff in charge of research ; the activities of the Bartol Research Foundation will be in charge of Dr. W. F. G. Swann.