The Auger effect in xenon and krypton

Abstract

In an earlier paper an account was given of a determination of the efficiency of emission of K series radiations from argon atoms ionized in the K shell. This efficiency, usually termed the K yield, was calculated from a statistical count of ordinary K photoelectron tracks and Auger pair tracks observed in a Wilson expansion chamber. These experiments have been extended to xenon and krypton, and the present paper describes the measurement of the K yields of these two gases. Determinations of the K yields for elements of high atomic number with the cloud expansion chamber should be of especial value, as other methods which depend on the measurement of X-ray energy by ionization currents encounter considerable difficulties owing to the increasing importance of scattering with short wave-length X-rays. The need for new measurements for the heavier elements has been emphasized recently by the striking divergence between the results of two extensive series of measurements, one due to Berkey and the other to Arends, both of whom used an ionization method. Berkey found a well-defined maximum in the K yield-atomic number curve in the neighbourhood of atomic number 44 after which the K yield suddenly decreased with increasing atomic number, an effect which is in direct contradiction with the experiments of Arends and existing theory. In connexion with the latter, too, measurements of the K yields for elements of high atomic number are of importance as calculations made recently by Massey and Burhop show that a relativistic treatment of the Auger effect yields rather lower values of the K yield for the higher atomic numbers than was expected by Burhop from his non-relativistic treatment.