Inventor: J W Geiger, W Müller

• Invented in 1908
• The Geiger counter is an instrument that detects and measures the intensity of radiation, such as particles from radioactive material, consisting of a Geiger tube and associated electronic equipment.

The Geiger counter was later replaced by the halogen counter, which became preferred for its longer life and lower operating voltage. Such detectors were and still are of importance for one can see its association with the time of invention of the theory of relativity; the nuclear reaction. The Geiger counter is crucial in that it measures the degree of radiation—the aspect of nuclear reactions that are as, if not more, fearful as the explosion itself.

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