Gas discharge mechanism of halogen-quenched counters

Abstract

Halogen-quenched counters may be divided into two groups I and II, comprising counters in which the ionization potential of the halogen molecules lies respectively above and below the metastable level of the rare gas atoms. In counters of group II the ionization of halogen molecules by metastably excited rare gas atoms and by resonance photons of the rare gas is supposed to play an important part in the multiplication. The resonance photons are absorbed and re-emitted many times before an excited rare gas atom ionizes a halogen molecule. Experiments with two counters in one glass envelope, one with a cylinder as cathode and one with a helically wound wire as cathode, show that the photo-effect at the cathode does not play a part in the multiplication process. When one of two identical counting systems in the same bent glass envelope discharges, the other is nearly always ignited by resonance photons of the first discharge, with a delay of the order of some microseconds. The propagation of the discharge parallel to the wire in most cases appears to be faster than the lateral spread of the discharge. The region below the starting potential has been explored with an α-particle source. An ionization chamber region and a proportional region have been found.