Photoelectrons and their Back Diffusion in Self-quenching Geiger–Müller Counters

Abstract

THE Thomsons's¹ equation is the only satisfactory theoretical approach to the problem of back diffusion of electrons. Though most simple in form, the value of its term C relating to the energy of electrons is very uncertain. Theobald's² results on photoelectric current measurements at varying X/p are in agreement with the Thomsons's theory in molecular gases, taking C equal to the most probable energy of emission of photoelectrons. The lack of agreement in the case of argon is attributed to the uncertainty in the electron drift velocity near the cathode. Likewise, Bradbury's³ values for mobility of electrons calculated using the Thomsons's equation are in agreement with those determined by direct methods. Few data are, however, available concerning the investigation of this subject in Geiger–Müller counters.