Geiger–Müller tube
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The Geiger–Müller tube or G–M tube is the sensing element of the Geiger counter instrument used for the detection of ionizing radiation. It is named after Hans Geiger, who invented the principle in 19
A complete Geiger counter, with the Geiger–Müller tube mounted in a cylindrical enclosure connected by a cable to the instrument
Visualization of the spread of Townsend avalanches by means of UV photons. This mechanism allows a single ionizing event to ionize all the gas surrounding the anode by triggering multiple avalanches.
Detection of gamma in a G-M tube with a thick-walled stainless steel cathode. Secondary electrons generated in the wall can reach the fill gas to produce avalanches. This effect is considerably attenuated at low energies below about 20 KeV
Pancake G–M tube, the circular concentric anode can clearly be seen.
Geiger counter is a colloquial name for any hand-held radiation measuring device in civil defense, but most civil defense devices were ion-chamber radiological survey meters capable of measuring only
Victoreen Civil Defense V-777-1 shelter radiation detection kit overview
An example of the CD V-715 survey meter.
The Civil Defense CD V-717 with detachable ionization chamber deployed. Ionization chamber portion sits atop yellow anti-contamination bag.
An example of the CD V-720 survey meter, turned upside down, showing the retractable beta shield.