G.M Tube (Geiger Mueller Counter Tube) is a most useful of the instrument used for detecting and measuring the energies α, β, Ƴ, and X-rays. It is sufficiently sensitive to detect individual α and β particles. It is also used to compare the activity of the radioactive substance.
Construction of Geiger-Mueller Counter Tube
It consists of a metallic cylindrical cathode tube enclosed in a glass envelope. A fine tungsten wire (anode wire) is stressed along the axes of the tube. The rays to be detected enters the tube through the glass envelope.
|Fig. G. M. Counter|
The total number of ion produced is now is independent of an initial number of ions (primary ions) formed by the entering particle.
Thus the entry of a single particle in the tube cause a pulse of current, which is amplified by pulse amplifier and the amplified pulse is sent to rate meter (scale).