A spark chamber is a particle detector: a device used in particle physics for detecting electrically charged particles. They were most widely used as research tools from the 1930s to the 1960s and have since been superseded by other technologies such as drift chambers and silicon detectors. Today, working spark chambers are mostly found in science museums and educational organisations, where they are used to demonstrate aspects of particle physics and astrophysics.
Spark chambers consist of a stack of metal plates placed in a sealed box filled with a gas such as helium, neon or a mixture of the two. When a charged particle from a cosmic ray travels through the box, it ionises the gas between the plates. Ordinarily this ionisation would remain invisible. However, if a high enough voltage can be applied between each adjacent pair of plates before that ionisation disappears, then sparks can be made to form along the trajectory taken by the ray, and the cosmic ray in effect becomes visible as a line of sparks. In order to control when this voltage is applied, a separate detector (often containing a pair of scintillators placed above and below the box) is needed. When this trigger senses that a cosmic ray has just passed, it fires a fast switch to connect the high voltage to the plates. The high voltage cannot be connected to the plates permanently, as this would lead to arc formation and continuous discharging.
As research devices, spark chamber detectors have lower resolution than bubble chamber detectors. However they can be made highly selective with the help of auxiliary detectors, making them useful in searching for very rare events.
A streamer chamber is a type of detector closely related to the spark chamber. In a spark chamber one looks at a stack of parallel plates edge-on. For this reason, best viewing is afforded when the particle comes in perpendicularly to the plates. A streamer chamber, in contrast, typically has only two plates, at least one of which is transparent (e.g. wire mesh or a conductive glass). Particles come in roughly parallel to the plane of these plates. A much shorter high-voltage pulse is used than with a spark chamber, so there is insufficient time for sparks to form. Instead very dim streamers of ionised gas are formed. These can be seen when image enhancement is applied.
Donald Arthur Glaser was an American physicist, neurobiologist, and the winner of the 1960 Nobel Prize in Physics for his invention of the bubble chamber used in subatomic particle physics.
In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a particle accelerator. Detectors can measure the particle energy and other attributes such as momentum, spin, charge, particle type, in addition to merely registering the presence of the particle.
A cloud chamber, also known as a Wilson cloud chamber, is a particle detector used for visualizing the passage of ionizing radiation.
In electronics, electrical breakdown or dielectric breakdown is a process that occurs when an electrically insulating material, subjected to a high enough voltage, suddenly becomes a conductor and current flows through it. All insulating materials undergo breakdown when the electric field caused by an applied voltage exceeds the material's dielectric strength. The voltage at which a given insulating object becomes conductive is called its breakdown voltage and, in addition to its dielectric strength, depends on its size and shape, and the location on the object at which the voltage is applied. Under sufficient voltage, electrical breakdown can occur within solids, liquids, or gases. However, the specific breakdown mechanisms are different for each kind of dielectric medium.
The proportional counter is a type of gaseous ionization detector device used to measure particles of ionizing radiation. The key feature is its ability to measure the energy of incident radiation, by producing a detector output pulse that is proportional to the radiation energy absorbed by the detector due to an ionizing event; hence the detector's name. It is widely used where energy levels of incident radiation must be known, such as in the discrimination between alpha and beta particles, or accurate measurement of X-ray radiation dose.
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 trajectory, by tracking the trails of gaseous ionization.
Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There are a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by various performance metrics, such as spectral response. Semiconductor-based photodetectors typically use a p–n junction that converts photons into charge. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy.
In physics, a time projection chamber (TPC) is a type of particle detector that uses a combination of electric fields and magnetic fields together with a sensitive volume of gas or liquid to perform a three-dimensional reconstruction of a particle trajectory or interaction.
The ionization chamber is the simplest type of gaseous ionisation detector, and is widely used for the detection and measurement of many types of ionizing radiation, including X-rays, gamma rays, alpha particles and beta particles. Conventionally, the term "ionization chamber" refers exclusively to those detectors which collect all the charges created by direct ionization within the gas through the application of an electric field. It uses the discrete charges created by each interaction between the incident radiation and the gas to produce an output in the form of a small direct current. This means individual ionising events cannot be measured, so the energy of different types of radiation cannot be differentiated, but it gives a very good measurement of overall ionising effect.
An electrostatic precipitator (ESP) is a filterless device that removes fine particles, such as dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit.
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.
A nitrogen laser is a gas laser operating in the ultraviolet range using molecular nitrogen as its gain medium, pumped by an electrical discharge.
An electron avalanche is a process in which a number of free electrons in a transmission medium are subjected to strong acceleration by an electric field and subsequently collide with other atoms of the medium, thereby ionizing them. This releases additional electrons which accelerate and collide with further atoms, releasing more electrons—a chain reaction. In a gas, this causes the affected region to become an electrically conductive plasma.
MACRO was a particle physics experiment located at the Laboratori Nazionali del Gran Sasso in Abruzzo, Italy. MACRO was proposed by 6 scientific institutions in the United States and 6 Italian institutions.
In electromagnetism, the Townsend discharge or Townsend avalanche is a 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 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.
A nuclear emulsion plate is a type of particle detector first used in nuclear and particle physics experiments in the early decades of the 20th century. It is a modified form of photographic plate that can be used to record and investigate fast charged particles like alpha-particles, nucleons, leptons or mesons. After exposing and developing the emulsion, single particle tracks can be observed and measured using a microscope.
The MicroMegas detector is a gaseous particle detector coming from the development of the wire chamber. Invented in 1992 by Georges Charpak and Ioannis Giomataris, the Micromegas detectors are mainly used in experimental physics, in particular in particle physics, nuclear physics and astrophysics for the detection of ionising particles.
In electromagnetism, a streamer discharge, also known as filamentary discharge, is a type of transient electric discharge which forms at the surface of a conductive electrode carrying a high voltage in an insulating medium such as air. Streamers are luminous writhing branching sparks, plasma channels composed of ionized air molecules, which repeatedly strike out from the electrode into the air.
X-ray detectors are devices used to measure the flux, spatial distribution, spectrum, and/or other properties of X-rays.
The 30 cm Bubble Chamber, prototyped as a 10 cm Bubble Chamber, was a particle detector used to study high-energy physics at CERN.
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