History
In 1908 Hans Geiger, under the supervision of Ernest Rutherford at the Victoria University of Manchester (now the University of Manchester), developed an experimental technique for detecting alpha particles that would later be used in the Geiger-muller tube. This counter was only capable of detecting alpha particles and was part of a larger experimental apparatus. The fundamental ionization mechanism used was discovered by John Sealy Townsend by his work between 1897 and 1901, and is known as the Townsend discharge, which is the ionization of molecules by ion impact.
It was not until 1928 that Geiger and Walther Müller (a PhD student of Geiger) developed the Geiger-Müller tube which could detect more types of ionizing radiation and it became a practical radiation sensor.
Once this improved sensor was available, Geiger counter instruments could be produced relatively cheaply because the large output pulse required little electronic processing to give a count rate reading, which was a distinct advantage in the thermionic valve era due to valve cost and power consumption.
Modern versions of the Geiger counter use the halogen tube invented in 1947 by Sidney H. Liebson. It superseded the earlier Geiger tube because of its much longer life and lower operating voltage, typically 400-600 volts.
Read more about this topic: Geiger Counter
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