Geiger–Müller tube

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Device for detecting alpha particles, beta particles, and gamma radiation, by measuring the electric current produced when these forms of radiation ionize a gas. The tube comprises an outer metal cylinder forming a negative terminal (cathode) with a thin membrane of plastic or mica covering the front of the tube. The inside of the tube is filled with argon gas and contains a metal rod at the centre forming a positive terminal (anode). Radiation from a sample travels through the thin membrane and ionizes the argon by removing electrons from the argon atoms. The electrons are attracted to the positively-charged rod. This flow of charge (an electric current) through the rod is converted to a digital reading on a Geiger counter.

Yellow symbolizes the golden land of South America. Red stands for courage and the blood of the freedom fighters. Blue represents the ocean separating South America from Spain. Effective date: 17 February 1954. >>