The Influence of Pressure and Collecting Field on Gamma Ray Ionization in Gases

The first part of this paper presents and discusses the conflicting theories which have been proposed to account for the observed dependence on pressure and collecting field of the ionization current in high pressure chamber electroscopes irradiated with γ -rays. The three types of recombination of ions in gases - preferential, initial, and volume - are considered in detail. The conclusion is drawn that, when low intensities are used, preferential recombination assumes a dominant role. The second part of the paper is devoted to an extension of the Compton, Bennett, and Stearns theory to include dependence on collecting field. Satisfactory agreement with Bowen's observations on air is obtained. The approximate, and partially empirical nature of the expressions developed prohibits a decisive test of the theory. The agreement found does demonstrate its fundamental correctness and superiority.