|
Gaseous Ionisation Detector
Gaseous ionization detectors are radiation detection instruments used in particle physics to detect the presence of ionizing particles, and in radiation protection applications to measure ionizing radiation. They use the ionising effect of radiation upon a gas-filled sensor. If a particle has enough energy to ionize a gas atom or molecule, the resulting electrons and ions cause a current flow which can be measured. Gaseous ionisation detectors form an important group of instruments used for radiation detection and measurement. This article gives a quick overview of the principal types, and more detailed information can be found in the articles on each instrument. The accompanying plot shows the variation of ion pair generation with varying applied voltage for constant incident radiation. There are three main practical operating regions, one of which each type utilises. Types The three basic types of gaseous ionization detectors are 1) ionization chambers, 2) proportional co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Detector Regions
A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends the information to other electronics, frequently a computer processor. Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, and in innumerable applications of which most people are never aware. With advances in micromachinery and easy-to-use microcontroller platforms, the uses of sensors have expanded beyond the traditional fields of temperature, pressure and flow measurement, for example into Attitude and heading reference system, MARG sensors. Analog sensors such as potentiometers and force-sensing resistors are still widely used. Their applications ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Townsend Avalanche
In electromagnetism, the Townsend discharge or 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 that permits significantly increased electrical conduction through the gas. The discharge requires a source of free electrons and a significant electric field; without both, the phenomenon does not occur. The Townsend discharge is named after John Sealy Townsend, who discovered the fundamental ionisation mechanism by his work circa 1897 at the Cavendish Laboratory, Cambridge. General description The avalanche occurs in a gaseous medium that can be ionised (such as air). The electric field and the mean free path of the electron must allow free electrons to acquire an energy level (velocity) that can cause impact ionisation. If the ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stopping Power (particle Radiation)
In nuclear and materials physics, stopping power is the retarding force acting on charged particles, typically alpha and beta particles, due to interaction with matter, resulting in loss of particle kinetic energy. Stopping power is also interpreted as the rate at which a material absorbs the kinetic energy of a charged particle. Its application is important in a wide range of thermodynamic areas such as radiation protection, ion implantation and nuclear medicine.ICRU Report 73: Stopping of Ions heavier than Helium, Journal of the ICRU, 5 No. 1 (2005), Oxford Univ. Press Definition and Bragg curve Both charged and uncharged particles lose energy while passing through matter. Positive ions are considered in most cases below. The stopping power depends on the type and energy of the radiation and on the properties of the material it passes. Since the production of an ion pair (usually a positive ion and a (negative) electron) requires a fixed amount of energy (for example, 33 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americium
Americium is a synthetic element, synthetic chemical element; it has Chemical symbol, symbol Am and atomic number 95. It is radioactive and a transuranic member of the actinide series in the periodic table, located under the lanthanide element europium and was thus named after the Americas by analogy. Americium was first produced in 1944 by the group of Glenn T. Seaborg from Berkeley, California, at the Metallurgical Laboratory of the University of Chicago, as part of the Manhattan Project. Although it is the third element in the transuranic series, it was discovered fourth, after the heavier curium. The discovery was kept secret and only released to the public in November 1945. Most americium is produced by uranium or plutonium being bombarded with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 100 grams of americium. It is widely used in commercial ionization chamber smoke detectors, as well as in neutron sources and industrial gauges. Several u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smoke Detector
A smoke detector is a device that senses smoke, typically as an indicator of fire. Smoke detectors/alarms are usually housed in plastic enclosures, typically shaped like a disk about in diameter and thick, but shape and size vary. Smoke can be detected either optically (Photodiode, photoelectric) or by physical process (ionization). Detectors may use one or both sensing methods. Sensitive detectors can be used to detect and deter smoking in banned areas. Smoke detectors in large commercial and industrial buildings are usually connected to a central fire alarm system. Household smoke detectors, also known as ''smoke alarms'', generally issue an audible or visual alarm from the detector itself or several detectors if there are multiple devices interconnected. Household smoke detectors range from individual battery-powered units to several interlinked units with battery backup. With interlinked units, if any unit detects smoke, alarms will trigger all of the units. This happens eve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Health And Safety Executive
The Health and Safety Executive (HSE) is a British public body responsible for the encouragement, regulation and enforcement of workplace health, safety and welfare. It has additionally adopted a research role into occupational risks in Great Britain. It is a non-departmental public body with its headquarters in Bootle, England. In Northern Ireland, these duties lie with the Health and Safety Executive for Northern Ireland. The HSE was created by the Health and Safety at Work etc. Act 1974, and has since absorbed earlier regulatory bodies such as the Factory Inspectorate and the Railway Inspectorate though the Railway Inspectorate was transferred to the Office of Rail and Road in April 2006. The HSE is sponsored by the Department for Work and Pensions. As part of its work, HSE investigates industrial accidents, small and large, including major incidents such as the explosion and fire at Buncefield in 2005. Though it formerly reported to the Health and Safety Commission, on 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geiger Counters
A Geiger counter (, ; also known as a Geiger–Müller counter or G-M counter) is an electronic instrument for detecting and measuring ionizing radiation with the use of a Geiger–Müller tube. It is widely used in applications such as radiation dosimetry, radiological protection, experimental physics and the nuclear industry. "Geiger counter" is often used generically to refer to any form of dosimeter (or, ''radiation-measuring device''), but scientifically, a Geiger counter is only one specific type of dosimeter. It detects ionizing radiation such as alpha particles, beta particles, and gamma rays using the ionization effect produced in a Geiger–Müller tube, which gives its name to the instrument. In wide and prominent use as a hand-held radiation survey instrument, it is perhaps one of the world's best-known radiation detection instruments. The original detection principle was realized in 1908 at the University of Manchester, but it was not until the development of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spread Of Avalanches In G-M Tube
Spread may refer to: Places * Spread, West Virginia Arts, entertainment, and media * ''Spread'' (film), a 2009 film. * '' $pread'', a quarterly magazine by and for sex workers * "Spread", a song by OutKast from their 2003 album '' Speakerboxxx/The Love Below'' * Spreadability, a concept in media studies * Page spread, an aspect of book design Finance * Spread, the difference in price between related securities, as in: ** Bid–offer spread, between the buying and selling price of a commodity and/or security ** Credit spread (bond), on bonds ** Option-adjusted spread, on mortgage backed securities where the borrower has the right to repay in full ** Options spread, building blocks of option trading strategies. ** Spread trade, between two related securities or commodities *** Spread option, payoff is based on the difference in price between two underlying assets ** Yield spread, difference in percentage rate of return of two instruments ** Z-spread, on mortgage backe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Electron Multiplier
A gas electron multiplier (GEM) is a type of gaseous ionization detector used in nuclear and particle physics and radiation detection. All gaseous ionization detectors are able to collect the electrons released by ionizing radiation, guiding them to a region with a large electric field, and thereby initiating an electron avalanche. The avalanche is able to produce enough electrons to create a current or charge large enough to be detected by electronics. In most ionization detectors, the large field comes from a thin wire with a positive high-voltage potential; this same thin wire collects the electrons from the avalanche and guides them towards the readout electronics. GEMs create the large electric field in small holes in a thin polymer sheet; the avalanche occurs inside of these holes. The resulting electrons are ejected from the sheet, and a separate system must be used to collect the electrons and guide them towards the readout. GEMs are one of the class of micropattern gaseou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microstrip Gas Chamber
Microstrip is a type of electrical transmission line which can be fabricated with any technology where a conductor is separated from a ground plane by a dielectric layer known as ''substrate''. Microstrip lines are used to convey microwave-frequency signals. Typical realisation technologies are printed circuit board (PCB), alumina coated with a dielectric layer or sometimes silicon or some other similar technologies. Microwave components such as antennas, couplers, filters, power dividers etc. can be formed from microstrip, with the entire device existing as the pattern of metallization on the substrate. Microstrip is thus much less expensive than traditional waveguide technology, as well as being far lighter and more compact. Microstrip was developed by ITT laboratories as a competitor to stripline (first published by Grieg and Engelmann in the December 1952 IRE proceedings). The disadvantages of microstrip compared with waveguide is the generally lower power handling capac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micropattern Gaseous Detectors
Micropattern gaseous detectors (MPGDs) are a group of gaseous ionization detectors consisting of microelectronic structures with sub-millimeter distances between anode and cathode electrodes. When interacting with the gaseous medium of the detector, particles of ionizing radiation create electrons and ions that are subsequently drifted apart by means of an electric field. The accelerated electrons create further electron-ion pairs in an avalanche process in regions with a strong electrostatic field. The various types of MPGDs differ in the way this strong field region is created. Examples of MPGDs include the microstrip gas chamber, the gas electron multiplier and the Micromegas detector. The main advantages of MPGDs over previous types of gaseous detectors, such as the multiwire proportional chamber A wire chamber or multi-wire proportional chamber is a type of proportional counter that detects charged particles and photons and can give positional information on their traject ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
