Geiger Counter
ALTERNATIVE NAME/S: Geiger-Müller counter
DETAILS/DESCRIPTION:
The Geiger counter, developed soon after 1906 by Hans Geiger* (and in 1928 improved by Walter Muller) is a device used to detect and measure the ionizing radiation given off by radioactive minerals and cosmic rays.
The instrument consists of a metal cylinder with a thin metal wire, typically made of tungsten, strung lengthwise inside a metal cylinder. The cylinder acts as one electrode and the wire acts as the other. The cylinder is sealed with glass insulators at both ends and filled with gas.
The gas conducts electricity only when some of its atoms have been ionized, or split up into free electrons and ions. A high voltage current applied to the device is almost, but not quite, strong enough to create a current through the gas. When any ionizing particles of radiation enter the gas-filled cylinder, the gas becomes ionized and therefore able to carry the current from one electrode to the other, completing the circuit.
Each ionized particle creates a brief electrical pulse. This is amplified electronically, activating a loudspeaker or a mechanical counting device, and creating an audible click. The gas mixture in the chamber then quickly returns to its usual non-ionized state. This allows each new particle to create its own click, and this makes particle-counting possible.
ONELINER: The Geiger counter
OTHER CONNECTIONS: None
BIBLIOGRAPHY:
Geiger Counters. Retrieved January 4, 2005, from http://www.kronjaeger.com/hv-old/radio/geiger/**
Geiger Counter. The Columbia Encyclopedia, Sixth Edition. 2001. Retrieved January 4, 2005, from http://www.bartleby.com/65/ge/Geigerco.html**
The Geiger Counter. Retrieved January 4, 2005, from http://www-istp.gsfc.nasa.gov/Education/wgeiger.html**
Particle Detectors. Funk & Wagnalls New Encyclopedia. Retrieved January 4, 2005, from OCLC FirstSearch.