GM tube stands for Geiger Muller tube. This tube is widely used in nuclear physics for detection and measurement of alpha particles, beta particles, and gamma rays.
It is widely applicable in medical purpose and in prospecting of radioactive ores.
It consist of hollow metal case which is enclosed in a thin glass tube with a fine tungsten wire which act as anode which is connected to positive terminal of battery and the negative terminal of battery is connected with metal surface.
Working:-It is based on the basic principle that when we apply a very high potential and an ionized gas is passed through it then the ions of the ionized gas will produce the secondary ions which is proportional to the energy of the primary ionization and the high energy which will comes out from window and cause the other atoms to ionize the gas filled in the tube.
Here the gas is argon and avalanche of argon ions produces and in this way many ions comes near to the wire and thus they create pulse and this pulse can be amplified and counted using amplifier which has pulse counter and loud speaker.