A preliminary note on branched α-ray tracks

Abstract

According to Prof. Sir E. Rutherford, if about one hundred thousand α-rays from radium C pass through the air, on the average there will be one close nuclear collision, which produces a swiftly moving atom. Thus, if we take a great number of photographs of α-ray tracks compatible with the above order of magnitude, we might expect to find some evidence to indicate the disruption of atoms by the α-particles. The present note is to describe some preliminary trials in this direction. The reciprocating expansion apparatus of the preceding article is very convenient for taking a large number of photographs within a reasonable time. Direct eye-observation confirmed the existence of some branched tracks which differed greatly in configuration from spurred tracks like the one photographed by Mr. C. T. R. Wilson. Arrangements were then made to devise a suitable method of photographing such tracks and to show their orientation in space.