A Mica Window Geiger Counter Tube for Measuring Soft Radiations

A mica window Geiger counter tube is described which combines the speed of a metal walled tube with a sensitivity to soft radiations comparable to that of the screen walled tubes. It consists of a NO2 treated metal cylinder covered at one end by a thin sheet of mica (0.02 mm) and at the other end by a glass bell with a central capillary. Through this capillary is sealed a piece of 8‐mil tungsten wire with a drop of glass fused over the end. The tube is operated at a pressure of 10 cm of Hg with a mixture of 10 percent ethanol and 90 percent argon.