The Synthesis and Disintegration of Atoms as Revealed by the Photography of Wilson Cloud Tracks

Abstract

IN 1923 Harkins and Ryan developed a simple method (NATURE, 112, 54; J. Am. Chem. Soc., 45, 2095) for obtaining a knowledge of what occurs when an atom disintegrates. This consisted of the use of very fast -rays, such as those of thorium or radium-C, in a modified Wilson (Shimizu) ray track apparatus, and the photography of an extremely large number of tracks. By the use of these fast rays, about 20,000 photographs in air and 21,000 in argon were obtained. Each photograph gave two views at right angles. That Wilson's apparatus had not been applied earlier for this purpose was undoubtedly due to the fact that it had previously seemed almost hopeless to obtain sufficient photographs.