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ATLAS (A Toroidal LHC ApparatuS) is one of the five detector experiments (ALICE, ATLAS, CMS, TOTEM, and LHCb) being constructed at the Large Hadron Collider at CERN in Switzerland. It will be 45 meters long, 25 meters in diameter, and weigh about 7,000 tons. The project involves roughly 2000 scientists and engineers at 151 institutions in 34 countries. The construction is scheduled to be completed in 2007. The experiment's goal is to make measurements of phenomena that involve highly-massive particles, especially new theories of particle physics beyond the Standard Model, which have not been measurable at previous particle accelerators. In experimental particle physics, a particle detector is a device used to track and identify high-energy particles, such as produced by nuclear decay, cosmic radiation, or reactions in a particle accelerator. ...
The Compact Muon Solenoid (CMS) experiment is a large particle physics detector being ( 2003) built on the proton-proton Large Hadron Collider (LHC) at CERN in Switzerland. ...
The LHCb (standing for Large Hadron Collider beauty) experiment is one of four large particle physics detector experiments being constructed on the Large Hadron Collider accelerator at CERN. LHCb is a specialist b-physics experiment, particularly aimed at measuring the parameters of CP-violation in the interactions of b-hadrons...
CMS detector for LHC at CERN The Large Hadron Collider (short LHC) is a particle accelerator and collider located at CERN. It is currently under construction and scheduled to start operation in 2007. ...
CERN logo CERN is the European Organization for Nuclear Research, the worlds largest particle physics laboratory, situated on the border between France and Switzerland, just west of Geneva. ...
metre or meter, see meter (disambiguation) The metre is the basic unit of length in the International System of Units. ...
metre or meter, see meter (disambiguation) The metre is the basic unit of length in the International System of Units. ...
The word ton or tonne is derived from the Old English tunne, and ultimately from the Old French tonne, and referred originally to a large cask with a capacity of 252 wine gallons, which holds approximately 2100 pounds of water. ...
This article is about the profession. ...
An engineer is someone who practices the engineering profession; a professional practitioner of engineering; someone who uses scientific knowledge to solve practical problems and produce goods for society. ...
2007 is a common year starting on Monday of the Gregorian calendar. ...
In particle physics, an elementary particle is a particle of which other, larger particles are composed. ...
In mathematics, theory is used informally to refer to a body of knowledge about mathematics. ...
Particles erupt from the collision point of two relativistic (100 GeV) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ...
The Standard Model of Fundamental Particles and Interactions The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. ...
One of the early particle accelerators responsible for development of the atomic bomb. ...
 ATLAS experiment detector being assembled (October 2004) Image File history File links Beschreibung: Kaverne des Atlas-Experiments im LHC am CERN Description: ATLAS detector being assebled in CERN Source: Image taken by Nikolai Schwerg Date: 16 Oktober 2004 (OpenDay 50 Years CERN) Author: Nikolai Schwerg Permission: Released in the GNU FDL domain by Juhanson Other versions of...
Image File history File links Beschreibung: Kaverne des Atlas-Experiments im LHC am CERN Description: ATLAS detector being assebled in CERN Source: Image taken by Nikolai Schwerg Date: 16 Oktober 2004 (OpenDay 50 Years CERN) Author: Nikolai Schwerg Permission: Released in the GNU FDL domain by Juhanson Other versions of...
Physics program
ATLAS will investigate several aspects and extensions of the Standard Model: The Standard Model of Fundamental Particles and Interactions The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. ...
- The hypothetical Higgs mechanism, which gives masses to elementary particles (in particular explaining the difference between the Weak force and Electromagnetism) and demands the existence of a particle called the Higgs boson
- CP violation, which explains the origin of matter/antimatter asymmetry
- Decays of the top quark and more precise determination of its mass
- The search for indications of Supersymmetry and or other new high-energy theories. If new beyond-the-standard-model physics is discovered experimentally, ATLAS data will be used to determine the features of that theory.
- The search for new, highly massive particles, which are usually the indicators of the theories mentioned above. They may also be the particles that compose Dark matter.
The Higgs mechanism, originally discovered by the British physicist Peter Higgs (building on a previous suggestion by Philip Anderson in condensed matter physics), is the mechanism that gives masses to all elementary particles in particle physics. ...
The weak nuclear force or weak interaction is one of the four fundamental forces of nature. ...
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ...
Higgs boson - Wikipedia, the free encyclopedia /**/ @import /skins-1. ...
CP-symmetry is a symmetry obtained by a combination of the C-symmetry and the P-symmetry. ...
The top quark is a third-generation quark with a charge of +2/3. ...
In particle physics, supersymmetry is a hypothetical symmetry that relates bosons and fermions. ...
In cosmology, dark matter consists of matter particles that cannot be detected by their emitted radiation but whose presence can be inferred from gravitational effects on visible matter such as stars and galaxies. ...
Components The ATLAS detector consists of four major parts: the Inner Detector, the calorimeters, the muon spectrometer, and the magnet systems.
Inner Detector The Inner Detector begins a few centimeters from the proton beam axis, extends to a radius of 1.2 m, and is 7 m in length along the beam pipe. Its basic function is to track charged particles, revealing a variety of detailed information about them. The Magnetic Field surrounding the entire inner detector causes charged particles to curve; the direction they curve in gives their charge, and how much they curve gives their momentum. The starting point of the tracks also yields useful information; if a group of tracks seems to originate from a point other than the original proton-proton collision, this is a sign that the particles came from the decay of a bottom quark (see B-tagging). The Inner Detector has three parts: Current flowing through a wire produces a magnetic field (M) around the wire. ...
In physics, momentum is a physical quantity related to the velocity and mass of an object. ...
For other uses of this term, see: Quark (disambiguation) 1974 discovery photograph of a possible charmed baryon In particle physics, the quarks are subatomic particles thought to be elemental and indivisible. ...
B-tagging is the name given to the special efforts required in modern Particle detectors to identify jets originating from bottom quarks (b-quarks). ...
Pixel Detector The Pixel Detector, the innermost part of the detector, contains 3 layers and 3 disks on each end cap. The smallest unit of this unit is a module. It contains of a pixel sensor 16 read out chip and a flex with a control chip an further electronic components. The smallest readout cell are the pixels (50 by 400 µm²) with rougly 47000 one one module with a size of about 2 by 6 cm². In total the Pixel Detector will have about 1700 modules whitch leads to over 80 million readout channels. This minute size enables extremely precise tracking very close to the interaction point. This large number of readout channels was one of the challenges for the Pixel Detector. Another one was/is the radiation due to close distance to the interaction point, so that all components have to be radiation tolerant. A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ...
One million (1000000), one thousand thousand, is the natural number following 999999 and preceding 1000001. ...
In particle physics, an interaction point (IP) is the place where particles collide. ...
Semi-Conductor Tracker The Semi-Conductor Tracker (SCT) is the middle component of the inner detector, and is composed of four double layers of sillicon strips. It has a total area of 61 m², and 6.2 million readout channels. A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ...
One million (1000000), one thousand thousand, is the natural number following 999999 and preceding 1000001. ...
Transition Radiation Tracker The Transition Radiation Tracker (TRT), the outermost component of the inner detector, is a combination of a straw tracker and a transition radiation detector. That is, it both tracks charged particles and determines whether they are highly relativistic. This aids in particle identification; particles relativistic enough to produce large amounts of transition radiation are usually electrons. It has 350,848 readout channels. A straw tracker is a type of Particle detector which uses many straw chambers to track the path of a particle. ...
A transition radiation detector (TRD) is a particle detector utilizing the -dependent threshold of transition radiation in a stratified material. ...
Albert Einsteins theory of relativity is a set of two theories in physics: special relativity and general relativity. ...
Particle identification refers to the process of using information left by an elementary particle passing through a particle detector to identify the type of particle. ...
Transition radiation is produced by relativistic charged particles when they cross the interface of two media of different dielectric constants. ...
Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ...
Calorimeter The calorimeters are situated outside the solenoidal magnet that surrounds the inner detector. Their purpose is to absorb the energy from particles, thereby measuring it. There are two basic calorimeter systems. Magnetic lines of force of a bar magnet shown by iron filings on paper A magnet is an object that has a magnetic field. ...
Particle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. ...
Electromagnetic calorimeter The Electromagnetic (EM) calorimeter absorbs energy from particles that interact electromagnetically, which include charged particles and photons. It has high precision, both in the amount of energy absorbed and in the precise location of the energy deposited. The energy-absorbing material is liquid argon, and a cryostat is required around the EM calorimeter to keep it sufficiently cool. Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ...
For the Science Fiction weapon, as seen in Star Trek, see Photon torpedo. ...
A liquid will assume the shape of its container. ...
General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ...
Cryocoolers are refrigerators used to reach cryogenic temperatures. ...
Hadron calorimeter The Hadron calorimeter absorbs energy from particles that pass through the EM Calorimeter but do interact via the Strong force, primarily neutral hadrons. It is less precise, both in energy magnitude and localization. The energy absorbing material is steel. Many of the features of the Calorimeter are chosen with cost-effectiveness in mind, because it is so large and has so much material; for example, the main part of the calorimeter (the Tile Calorimeter) is 8m in diameter and covers 12m along the beam axis. In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ...
The strong nuclear force or strong interaction (also called color force or colour force) is a fundamental force of nature which affects only quarks and antiquarks, and is mediated by gluons in a similar fashion to how the electromagnetic force is mediated by photons. ...
Neutral means balanced between two or more opposites. ...
// Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ...
Muon spectrometer The Muon spectrometer is an extremely large straw tracker, extending from the calorimeters out to the full diameter of the detector. Its purpose is to measure the momentum of muons, which pass through all other layers of the detector, by observing their curvature in the toroidal magnetic field. It has over one million readout channels, and its layers of detectors have a total area of 12000 m². The moons shadow, as seen in muons 700m below ground at the Soudan 2 detector. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
A straw tracker is a type of Particle detector which uses many straw chambers to track the path of a particle. ...
Current flowing through a wire produces a magnetic field (M) around the wire. ...
A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ...
Magnet system
Inner solenoid The inner solenoid produces a 2 tesla magnetic field surrounding the inner detector, causing even very energetic particles to curve enough that their momentum can be determined. In engineering, a solenoid is a mechanical device that converts energy into linear motion. ...
The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic inductivity). ...
Outer toroid The outer toroidal magnetic field is produced by very large eight large barrel loops and two endcaps, all situated outside the calorimeters and within the muon system. The total volume of the magnetic field is 26 meters long and 20 meters in diameter, and stores 1.2 billion joules of energy. It bends muons which escape the other parts of the detector, so that their momentum can be measured. A toroid is a doughnut-shaped object whose surface is a torus. ...
metre or meter, see meter (disambiguation) The metre is the basic unit of length in the International System of Units. ...
metre or meter, see meter (disambiguation) The metre is the basic unit of length in the International System of Units. ...
The word billion, and its equivalents in other languages, refer to one of two different numbers. ...
The joule (symbol J, also called newton meter, watt second, or coulomb volt) is the SI unit of energy and work. ...
Data systems
Trigger and data aquisition The trigger system uses simple information to identify, in real time, the most interesting events out of the 40 million beam crossings that occur every second in the center of the detector. After the first level, about 100,000 events per second have been selected. After the third-level trigger, a few hundred events remain to be stored for further analysis. A beam crossing in a particle collider occurs when two packets of particles, going in opposite directions, reach the same point in space. ...
Computing Offline event reconstruction will be performed on all permenantly stored events, turning the pattern of signals from the detector into physics objects like jets, photons, and leptons. Individuals within the collaboration can write their own code to do further analysis of these objects. The software for these tasks has been under development for many years, and will continue to be refined even once the experiment is running. In a particle detector experiment, reconstruction is the process of interpreting the electronic signals produced by the detector to determine the original particles that passed through. ...
A jet is a narrow cone of hadrons and other particles produced by the hadronization of a quark or gluon in a Particle physics experiment. ...
For the Science Fiction weapon, as seen in Star Trek, see Photon torpedo. ...
In physics, a particle is a lepton if it has a spin of 1/2 and does not experience the strong nuclear force. ...
Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ...
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