The development of end-window Geiger-Mÿller counter tubes

The paper gives an account of the various stages in the development of end-window self-quenching Geiger-Mÿller counter tubes for the detection of ß-particles. Commencing as a tube using the feather-edge type of copper-to-glass seal, one inch in diameter, with a copper-foil end window, the design was later modified to one more suitable for production on a larger scale, employing a standard Kovar/glass eyelet seal, the assembly of all metallic joints being effected by means of soft solder. To permit the detection of slower ß-particles, a similar tube was developed having a Duralumin window of thickness 1 mil, which was soldered to an electroplated copper layer. The assembly process was subsequently simplified by use of a thermosetting plastic adhesive wax called ¿Araldite¿. For the detection of very slow ß-particles it was necessary to use a mica window of about 0.25-mil thickness, and a suitable seal, using Araldite, was devised for windows of this material. It was found during the course of development that extreme purity of the filling gas and quenching vapour was unnecessary, and less rigorous pumping than that associated with most electronic tubes was also permissible, the most important factors in obtaining good tubes being cleanliness and freedom from loose particles and lint.