On the ionisation of various gases by α-, β-, and γ-rays

Abstract

When an ionising agent traverses a gas, the ionisation between two parallel planes separated by a distance δ x is measured by K. δ x , where K denotes the ionisation per cubic centimetre when it is ionised throughout by an intensity of the ionising agent equal to that between the planes. In order to obtain values of K in practice, the gases under investigation are reduced to such low pressures that they absorb only a small fraction of the energy of the ionising agent, and a set of readings with different gases then gives their respective values of K for the intensity of the ionising agent where it enters the ionisa­tion chamber. A test that the absorption of energy in the gas is small is that the ionisation is directly proportional to the pressure. Strutt has carried out a set of experiments on the ionisation of a number of gases by α-, β-, and γ-rays. This paper gives the ionisation of a larger number of gases for these rays and the conclusions which may be deduced from the results of the experiments. Let us first consider the α-particle.