 A deflection needle type geiger counter |
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| Other names | Geiger-Müller counter |
|---|---|
| Uses | Particle detector |
| Inventor | Hans Geiger |
| Related items | Geiger-Müller tube |
A Geiger counter, also called a Geiger-Müller counter, is a type of particle detector that measures ionizing radiation. They are notable for being used to detect if objects emit nuclear radiation.
Geiger counters are used to detect ionizing radiation (usually beta particles and gamma rays, but certain models can detect alpha particles). An inert gas-filled tube (usually helium, neon or argon with halogens added) briefly conducts electricity when a particle or photon of radiation makes the gas conductive. The tube amplifies this conduction by a cascade effect and outputs a current pulse, which is then often displayed by a needle or lamp and/or audible clicks. Modern instruments can report radioactivity over several orders of magnitude.
Some Geiger counters can be used to detect gamma radiation, though sensitivity can be lower for high energy gamma radiation than with certain other types of detector, because the density of the gas in the device is usually low, allowing most high energy gamma photons to pass through undetected (lower energy photons are easier to detect, and are better absorbed by the detector. Examples of this are the X-ray Pancake Geiger Tube). Improved gamma sensitive Geiger-Müller tubes with high density cathodes (walls) of lead or stainless steel were used to overcome this difficulty. Gamma photons interact with the walls producing high-energy electrons which are then detected.
A better device for detecting gamma rays is a sodium iodide scintillation counter. Good alpha and beta scintillation counters also exist, but Geiger detectors are still favored as general purpose alpha/beta/gamma portable contamination and dose rate instruments, due to their low cost and robustness. A variation of the Geiger tube is used to measure neutrons, where the gas used is boron trifluoride and a plastic moderator is used to slow the neutrons. This creates an alpha particle inside the detector and thus neutrons can be counted.
Electric lamps and discharge devices of the Geiger-Müller type (Class 313/93)
| This article's introduction section may not adequately summarize its contents. To comply with Wikipedia's lead section guidelines, please consider expanding the lead to provide an accessible overview of the article's key points. (August 2009) |
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File:Geiger A deflection needle type geiger counter | |
| Other names | Geiger-Müller counter |
|---|---|
| Uses | Particle detector |
| Inventor | Hans Geiger |
| Related items | Geiger-Müller tube |
A Geiger counter, also called a Geiger-Müller counter, is a type of particle detector that measures ionizing radiation. They are notable for being used to detect whether objects emit nuclear radiation.
Geiger counters are used to detect ionizing radiation (usually beta particles and gamma rays, but certain models can detect alpha particles). An inert gas-filled tube (usually helium, neon or argon with halogens added) briefly conducts electricity when a particle or photon of radiation makes the gas conductive. The tube amplifies this conduction by a cascade effect and outputs a current pulse, which is then often displayed by a needle or lamp and/or audible. Modern instruments can report radioactivity over several orders of magnitude. Some Geiger counters can be used to detect gamma radiation, though sensitivity can be lower for high energy gamma radiation than with certain other types of detector, because the density of the gas in the device is usually low, allowing most high energy gamma photons to pass through undetected (lower energy photons are easier to detect, and are better absorbed by the detector. Examples of this are the X-ray Pancake Geiger Tube). Improved gamma sensitive Geiger-Müller tubes with high density cathodes (walls) of lead or stainless steel were used to overcome this difficulty. Gamma photons interact with the walls producing high-energy electrons which are then detected.
A better device for detecting gamma rays is a sodium iodide scintillation counter. Good alpha and beta scintillation counters also exist, but Geiger detectors are still favored as general purpose alpha/beta/gamma portable contamination and dose rate instruments, due to their low cost and robustness. A variation of the Geiger tube is used to measure neutrons, where the gas used is boron trifluoride and a plastic moderator is used to slow the neutrons. This creates an alpha particle inside the detector and thus neutrons can be counted.
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Wikimedia Commons has media related to: Geiger counter |
Electric lamps and discharge devices of the Geiger-Müller type (Class 313/93)
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Named after Hans Geiger who developed the first such device in 1908 together with Ernest Rutherford.
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Singular |
Plural |
Geiger counter (plural Geiger counters)
A Geiger counter (sometimes called Geiger-Müller counter) is an instrument that measures radiation in an area. It works by measuring ionizing radiation by count rate. It was developed by Hans Geiger and Ernest Rutherford in 1908. It was improved by Walther Müller in 1928.
Geiger counters can detect the presence of radiation. Some can also detect the intensity of it, and the angle from which it comes.
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   | How a Geiger counter works. - The Vega Science Trust - The Geiger Counter |
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