Geiger Counter Tubes

The following are some of the many processes that contribute to the mechanism of the discharge in Geiger counters: formation of the primary ion pairs; ion multiplication within the gas by Townsend avalanche formation; spreading of the avalanches through photoelectric absorption of ultra-violet quanta in the gas; transfer of ionization energy from positive ions of the rare gases to the polyatomic molecules of the "quenching" admixture; release of secondary electrons at the cathode by positive ions and metastable atoms; de-excitation of metastable atoms of the rare gases by colisions with atoms of admixed foreign gases; and decomposition of poly-atomic molecules by electron impacts and photon absorption. Present theories provide a qualitative understanding of the fundamental roles played by all of these processes, but their combined effects are too complex to predict the wide variation in characteristics of tubes obtained with slightly altered practices of construction or choices of gases. This paper is a review of existing theories and methods of constructing tubes to obtain maximum counting efficiencies and other desirable characteristics, such as low threshold voltage, thermal insensitivity, long life, high resolution, and low background.