In 1908 physicists Hans Geiger (1882-1945) and Ernest Rutherford (1871-1937) were observing ionized helium atoms at Manchester University and wanted to confirm the data from their scintillation crystal counters. Their new "Geiger" counter consisted of a high-voltage wire running along the central axis of a sealed brass cylindrical tube containing low-pressure carbon dioxide. When charged particles entered through a window in the chamber they collided with and ionized CO2 molecules leading to a voltage change on the central wire that was registered on a galvanometer. A count rate of five to ten per minute could be registered. Soon more sophisticated detectors using helium gas and a photographic voltage registration were introduced, increasing the count rate to about a thousand per minute. In 1928 improvements made in the electrical characteristics by Walther Muller (one of Geiger's PhD students) enabled the instrument to detect electrons.
The main problem was the recovery time—the "dead time" between recording a particle and being ready to record the next one. This was considerably reduced in the 1930s by adding ethyl alcohol to the CO2 as a quenching agent thus quickly gathering up the ionization after a particle had passed through.
Many Geiger counters were used in the nuclear weapons industry during World War II, and the nuclear power industry afterward. They had been developed into cheap and robust instruments, and their urgent clicking sound, indicating the presence and intensity of ionizing particle radiation, has become a common feature in cold war and science-fiction films.
