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A Geiger counter, also called a '''Geiger-Müller counter''', measures Ionizing Radiation . DESCRIPTION Geiger counters can be used to detect Alpha and Beta Radiation . The sensor is a Geiger-Müller Tube , a gas-filled tube that briefly conducts electricity when a Particle or Photon of radiation briefly makes the gas (normally inert Argon gas) conductive. The instrument amplifies this signal and displays it to the user, either as a current measurement (needle, lamp) or an audible click, with one click for each single particle. Under some conditions Geiger counters can be used to detect Gamma Radiation , though not reliably. Due to the fact that the density of the gas is so low, it is unlikely that a gamma photon will interact with the gas in a GM tube, hence the GM tube is very insensitive to gamma rays. A much better device for detecting gamma rays is a Sodium iodide Scintillation Counter . However, the window on the Scintillation Counter is too thick to allow beta particles to enter the detector. It is vital that the correct detector is chosen for the radiation which is to be tested for. Geiger counters cannot be used to detect Neutrons . TYPES AND APPLICATIONS The Geiger-Müller tube is one form of a class of radiation detectors called ''gaseous detectors'' or simply gas detectors. Although useful, cheap and robust, a counter using a GM tube can only detect the presence and intensity of radiation. Gas detectors with the ability to both detect radiation and determine particle energy levels (due to their construction, test gas, and associated electronics) are called Proportional Counter s. Some proportional counters can detect the position and/or angle of the incident radiation as well. Other devices detecting radiation include: Ionization Chamber , Dosimeter s, Photomultiplier , Semiconductor Detector s and variants including CCD s, Microchannel Plate s, Scintillation Counter s, solid-state Track Detector s, Cloud Chamber s, Bubble Chamber s, Spark Chamber s, Neutron Detector s and Microcalorimeter s. The Geiger-Müller counter has applications in the fields of Nuclear Physics , Geophysics ( Mining ) and medical therapy with isotopes. Some of the proportional counter have many internal wires and electrodes and are called Multi-wire Proportional Counter s or simply MWPCs. Radiation detectors have also been used extensively in nuclear physics, Medicine , Particle Physics , Astronomy and in industry. HISTORY Hans Geiger developed a device (what would later be called the "''Geiger counter''") in 1908 together with Ernest Rutherford . This counter was only capable of detecting alpha particles. In 1928 , Geiger and Walther Müller (a PhD student of Geiger) improved the counter so that it could detect all kinds of ionizing radiation. The current version of the "Geiger counter" is called the ''halogen counter''. It was invented in 1947 by Sidney H. Liebson (Phys. Rev. 72, 602–608 (1947)). It has superseded the earlier Geiger counter because of its much longer life. The devices also possessed a lower operating voltage. SEE ALSO ;General
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;Radiation EXTERNAL LINKS ;Patents Electric lamps and discharge devices of the Gieger-Müller type (Class 313/93)
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