Early Geiger counter, made by Hans Geiger, 1932. (9663806938)

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Science Museum London / Science and Society Picture Library

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Early Geiger counter, made by Hans Geiger, 1932.

• Uploaded by Mrjohncummings

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https://sewiki.info/b/2f005

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Wikimedia Commons

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1250 x 935 Pixel (144046 Bytes)

Beskrivning:

Hans Geiger (1882-1945) worked closely with Ernest Rutherford (1871-1935) to develop radiation measuring devices, particularly in 1908 when the Townsend avalanche effect was used in a laboratory rig to obtain measurable bursts of current from ionisation due to alpha particles. This made an important contribution to the early understanding of the nature of alpha particles. Later, in 1928, this ionisation effect was used in a practical tube developed by Geiger and Walther Müller to also measure gamma radiation. In this early example of a Geiger-Muller tube a low pressure gas is held in a metal cylinder fitted with an insulated handle. An electrical voltage is applied between the cylinder (Cathode) and a thin wire anode running axially along its centre which produces a strong electric field in the gas. Gamma radiation impinging on the cylinder produces electrons in the wall by the photoelectic effect, which then enter and ionise the gas to cause a measurable burst of electric current which is registered on a counter. This particular Geiger tube was used by James Chadwick, the discoverer of the neutron.

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CC BY-SA 2.0

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Creative Commons Attribution-Share Alike 2.0