The study of forked α-ray tracks

Abstract

If the Wilson Condensation Method is used to photograph a large number of α-ray tracks, occasional sudden bends will be noticed, due to the collision of the α-particles with the atoms of the gas in the expansion chamber. In a previous paper, a description was given of a method of analysing statistically the numbers of these bends, so as to give the speed of the α-particles and the law of force surrounding the nuclei of the gas atoms. The first part of the following paper is concerned with the lengths of the tracks of the recoil atoms set in motion by the α-particles, and leads directly to a knowledge of the relation between their range and velocity. The recoil atoms dealt with are the atoms of hydrogen, helium, air and argon. From these results the relative ionisation due to the four types of particles is calculated.