Detector (gas amplification)

The Townsend avalanche is an ionisation process for gases where free electrons are accelerated by an electric field, collide with gas molecules, and consequently free additional electrons. Those electrons are in turn accelerated and free additional electrons. The result is an avalanche multiplication of free electrons known as gas amplification (see Figure).

History

The phenomenon was discovered around 1897 by the Irish physicist John Sealy Edward Townsend (1868 – 1957).

Related concepts

• detector (ionization)
• detector (photographic emulsion)
• detector (scintillation)