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Encyclopedia > Compact Muon Solenoid

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The sentence "producing a rare particle, such as a Higgs boson" proves this article was not written and checked by physicists, despiste ip are from cern.ch domain. Ask the CMS collaboration to wrote a good article or add just a link to their web site!


Coordinates: 46°18′34″N 6°4′37″E / 46.30944, 6.07694 Map of Earth showing lines of latitude (horizontally) and longitude (vertically), Eckert VI projection; large version (pdf, 1. ...


The accelerator chain of the
Large Hadron Collider (LHC)
LHC experiments
ATLAS A Toroidal LHC ApparatuS
CMS Compact Muon Solenoid
LHCb LHC-beauty
ALICE A Large Ion Collider Experiment
TOTEM Total Cross Section, Elastic
Scattering and Diffraction Dissociation
LHCf LHC-forward
LHC preaccelerators
p and Pb Linear accelerators
for protons and Lead
(not marked) Proton Synchrotron Booster
PS Proton Synchrotron
SPS Super Proton Synchrotron
View of the CMS endcap through the barrel sections. The yellow arm of the cherry-picker gives an impression of scale
View of the CMS endcap through the barrel sections. The yellow arm of the cherry-picker gives an impression of scale

The Compact Muon Solenoid (CMS) experiment is one of two large general-purpose particle physics detectors being (as of 2006) built on the proton-proton Large Hadron Collider (LHC) at CERN in Switzerland. Approximately 2300 people from 159 scientific institutes form the collaboration building it. It will be located in an underground chamber at Cessy in France, just across the border from Geneva. The completed detector will be cylindrical, 21 metres long and 16 metres diameter and weigh approximately 12500 tonnes. Image File history File links LHC.svg‎ PNG version. ... The Large Hadron Collider (LHC) is a particle accelerator and collider located at CERN, near Geneva, Switzerland ( ). Currently under construction, the LHC is scheduled to begin operation in May 2008. ... ATLAS experiment detector under construction in October 2004 in its experimental pit; the current status of construction can be seen here. ... 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... ALICE (A Large Ion Collider Experiment) is one of the five detector experiments (ALICE, ATLAS, CMS, TOTEM, and LHCb) being constructed at the Large Hadron Collider at CERN. It is optimized to study heavy ion collisions. ... A totem is any entity which watches over or assists a group of people, such as a family, clan or tribe (Merriam-Webster Online Dictionary [1] and Websters New World College Dictionary, Fourth Edition). ... The LHCf (standing for Large Hadron Collider forward) experiment is one of six particle physics detector experiments being constructed on the Large Hadron Collider accelerator at CERN. ... A Linear particle accelerator is an electrical device for the acceleration of subatomic particles. ... In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... For Pb as an abbreviation, see PB. General Name, Symbol, Number lead, Pb, 82 Chemical series Post-transition metals or poor metals Group, Period, Block 14, 6, p Appearance bluish gray Standard atomic weight 207. ... The PS Booster is the first and smallest proton circular accelerator in the CERN LHC injection complex [1]. It takes 50MeV protons from the linear accelerator Linac2 and accelerates them up to 1. ... The surface above the PS at CERN. With more than 45 years to be smoothed out and have buildings built around it, the ring-shaped hill containing the accelerator is not completely obvious--but it can be seen curving around on the left side of the image. ... The Super Proton Synchrotron (SPS) is a particle accelerator at CERN. Originally specified as a 300 GeV machine, the SPS was actually built to be capable of 400GeV, an operating energy it achieved on the official commissioning date of 17 June 1976. ... Image File history File links Size of this preview: 800 × 524 pixelsFull resolution (2963 × 1941 pixel, file size: 1. ... Image File history File links Size of this preview: 800 × 524 pixelsFull resolution (2963 × 1941 pixel, file size: 1. ... Thousands of particles explode from the collision point of two relativistic (100 GeV per ion) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... The Compact Muon Solenoid (CMS) is an example of a large particle detector. ... Year 2006 (MMVI) was a common year starting on Sunday (link displays full 2006 calendar) of the Gregorian calendar. ... In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... The Large Hadron Collider (LHC) is a particle accelerator and collider located at CERN, near Geneva, Switzerland ( ). Currently under construction, the LHC is scheduled to begin operation in May 2008. ... CERN logo The European Organization for Nuclear Research (French: ), commonly known as CERN (see Naming), pronounced (or in French), is the worlds largest particle physics laboratory, situated just northwest of Geneva on the border between France and Switzerland. ... Coat of arms of the Canton of Geneva Coat of arms of the City of Geneva Geneva (French: Genève, German: Genf, Italian: Ginevra, Romansh Genevra, Spanish: Ginebra) is the second-most populous city in Switzerland (after Zurich), located where Lake Geneva (French: Lac de Genève or Lac L...


Goals

The main goals of the experiment are:

  • to explore physics at the TeV scale
  • to discover the Higgs boson
  • to look for evidence of physics beyond the standard model, such as supersymmetry, or extra dimensions
  • to be able to study aspects of heavy ion collisions

A TeV is a teraelectronvolt, i. ... The Higgs boson is a hypothetical massive scalar elementary particle predicted to exist by the Standard Model of particle physics. ... This article or section is in need of attention from an expert on the subject. ... Kaluza-Klein theory (or KK theory, for short) is a model which sought to unify classical gravity and electromagnetism. ...

Highlights

The main highlight features of the detector:

  • Its relatively small size
  • The powerful solenoid magnet
  • Its optimization for tracking muons

The muon (from the letter mu (μ)--used to represent it) is an elementary particle with negative electric charge and a spin of 1/2. ...

Detector overview

CMS is designed as a general-purpose detector, capable of studying many aspects of proton collisions at 14 TeV, the center-of-mass energy of the LHC particle accelerator. It contains subsystems which are designed to measure the energy and momentum of photons, electrons, muons, and other products of the collisions. The innermost layer is a silicon-based tracker. Surrounding it is a scintillating crystal electromagnetic calorimeter, which is itself surrounded with a sampling calorimeter for hadrons. The tracker and the calorimetry are compact enough to fit inside the CMS solenoid which generates a powerful magnetic field of 4 T. Outside the magnet are the large muon detectors, which are inside the return yoke of the magnet. In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... A TeV is a teraelectronvolt, i. ... The Large Hadron Collider (LHC) is a particle accelerator and collider located at CERN, near Geneva, Switzerland ( ). Currently under construction, the LHC is scheduled to begin operation in May 2008. ... In classical mechanics, momentum (pl. ... In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ... In the Standard Model of particle physics, a muon (Greek μείον = minus) is a semistable fundamental particle with negative electric charge and a spin of 1/2. ... Scintillation is a flash of light produced in a transparent material by an ionizing event. ... Stozite is a mineral, Lead tungstate; formula PbWO4. ... In particle physics, a calorimeter is an experimental apparatus that measures the energy of particles. ... Various solenoid actuators from Trombetta Motion Technologies A solenoid is a loop of wire, often wrapped around a metallic core, which produces a magnetic field when an electrical current is passed through it. ...

The set up of the CMS. In the middle, under the so-called barrel there is a man for the scale. (HCAL=hadron calorimeter, ECAL=electromagnetic calorimeter)
The set up of the CMS. In the middle, under the so-called barrel there is a man for the scale. (HCAL=hadron calorimeter, ECAL=electromagnetic calorimeter)

Image File history File links Download high resolution version (805x421, 75 KB) Summary A poster about the set up of the Compact Muon Solenoid (CMS) and the countries that build it. ... Image File history File links Download high resolution version (805x421, 75 KB) Summary A poster about the set up of the Compact Muon Solenoid (CMS) and the countries that build it. ...

The layers of CMS – from the center outwards

A slice of the CMS detector. Flash animation can be reached here

Image File history File links Download high resolution version (992x506, 95 KB) Source: http://cmsinfo. ... Image File history File links Download high resolution version (992x506, 95 KB) Source: http://cmsinfo. ...

The collision region - at the center

This is where the protons smash into each other. The focusing magnets in the LHC force the proton beams, traveling in opposite directions, to cross at the center of the CMS detector. In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... The Large Hadron Collider (LHC) is a particle accelerator and collider located at CERN, near Geneva, Switzerland ( ). Currently under construction, the LHC is scheduled to begin operation in May 2008. ...


The beams are arranged into "bunches" of protons. Each bunch contains approximately 100 billion protons. The particles are so tiny that the chance of any two colliding is very small. When the bunches cross, there will be only about 20 collisions among 200 billion particles.


When two protons collide at such high energy, they are ripped apart, and the exchange of mass and energy means that particles which do not usually occur in the world around us can be created. Most of these processes are already well understood - only around 100 in every 1 billion collisions will produce "interesting" physics.


Consequently, the bunches are spaced closely in the beam, so that there are 40 million bunch crossings per second - one every 25ns. To help compare orders of magnitude of different times this page lists times between 10−9 seconds and 10−8 seconds (1 nanosecond and 10 nanoseconds) See also times of other orders of magnitude. ...


Layer 1 – The tracker

Finely segmented silicon sensors (strips and pixels) enable charged particles to be tracked and their momenta to be measured. They also reveal the positions at which long-lived unstable particles decay. A semiconductor particle detector is a device that uses a semiconductor (usually silicon) to detect the passage of charged particles. ...


Layer 2 – The electromagnetic calorimeter

Nearly 80 000 crystals of scintillating lead tungstate (PbWO4) are used to measure precisely the energies of electrons and photons. A ‘preshower’ detector, based on silicon sensors, helps particle identification in the endcaps. Scintillation is a flash of light produced in a transparent material by an ionizing event. ... Stozite is a mineral, Lead tungstate; formula PbWO4. ... Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ... In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... A semiconductor particle detector is a device that uses a semiconductor (usually silicon) to detect the passage of charged particles. ...

The silicon strip tracker of CMS
Preparing Lead Tungstate Crystals for the ECAL
Preparing Lead Tungstate Crystals for the ECAL

Image File history File links Metadata Size of this preview: 800 × 536 pixelsFull resolution (3872 × 2592 pixel, file size: 2. ... Image File history File links Metadata Size of this preview: 800 × 536 pixelsFull resolution (3872 × 2592 pixel, file size: 2. ... Image File history File links Size of this preview: 800 × 533 pixelsFull resolution (984 × 656 pixel, file size: 546 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Size of this preview: 800 × 533 pixelsFull resolution (984 × 656 pixel, file size: 546 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Layer 3 – The hadron calorimeter

Half of the Hadron Calorimeter
Half of the Hadron Calorimeter

Layers of dense material (brass or steel) interleaved with plastic scintillators or quartz fibers allow the determination of the energy of hadrons, that is, particles such as protons, neutrons, pions and kaons. The brass used in the endcaps of the HCAL used to be Russian artillery shells. [1] Image File history File links Metadata No higher resolution available. ... Image File history File links Metadata No higher resolution available. ... For other uses, see Brass (disambiguation). ... The steel cable of a colliery winding tower. ... Scintillation is a flash of light produced in a transparent material by an ionizing event. ... In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ... For alternative meanings see proton (disambiguation). ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV/c² (1. ... In particle physics, pion (short for the Greek pi meson = P middle) is the collective name for three subatomic particles discovered in 1947: π0, π+ and π−. Pions are the lightest mesons. ... In particle physics, a kaon (also called K-meson and denoted K) is any one of a group of four mesons distinguished by the fact that they carry a quantum number called strangeness. ...


Layer 4 – The magnet

Like most particle physics detectors, CMS has a large solenoid magnet. This allows the charge/mass ratio of particles to be determined from the curved track that they follow in the magnetic field. It is 13 meters long and 6 meters in diameter, and its refrigerated superconducting niobium-titanium coils will produce a 4-tesla magnetic field. Various solenoid actuators from Trombetta Motion Technologies A solenoid is a loop of wire, often wrapped around a metallic core, which produces a magnetic field when an electrical current is passed through it. ... SI unit. ...


The inductance of the magnet is 14 Henries and the nominal current is 19500 Amps, giving a total stored energy of 2.66 GJ, equivalent to about half-a-tonne of TNT. There are dump circuits to safely dissipate this energy should the magnet quench. The circuit resistance (essentially just the cables from the power converter to the cryostat) have a resistance of 0.1 milliohms which leads to a circuit time constant of nearly 39 hours. This is the longest time constant of any circuit at CERN. The henry (symbol H) is the SI unit of inductance. ... Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current. ... GJ is an abbreviation that can refer to the following: Eurofly IATA airline designator Generic Java programming language gigajoule, a unit of energy Gliese-Jahreiss star catalogue An online gaming or instant messaging abbreviation corresponding to good job, sometimes used in a sarcastic manner GreatestJournal grapefruit juice or grape juice... R-phrases S-phrases Related Compounds Related compounds picric acid hexanitrobenzene Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Trinitrotoluene (TNT) is a chemical compound with the formula C6H2(NO2)3CH3. ... A quench refers to a rapid cooling. ... Cryocoolers are refrigerators used to reach cryogenic temperatures. ...


Layer 5 – The muon detectors and return yoke

To identify muons (essentially heavy electrons) and measure their momenta, CMS uses three types of detector: drift tubes (DT), cathode strip chambers (CSC) and resistive plate chambers (RPC). The DT's are used for precise trajectory measurements in the central barrel region, while the CSC's are used in the end caps. The RPC's provide a fast signal when a muon passes through the muon detector, and are installed in both the barrel and the end caps. In the Standard Model of particle physics, a muon (Greek μείον = minus) is a semistable fundamental particle with negative electric charge and a spin of 1/2. ... This article needs cleanup. ...

The Hadron Calorimeter Barrel (in the foreground, on the yellow frame) waits to be inserted into the superconducting magnet (the silver cylinder in the centre of the red magnet yoke).
The Hadron Calorimeter Barrel (in the foreground, on the yellow frame) waits to be inserted into the superconducting magnet (the silver cylinder in the centre of the red magnet yoke).
A part of the Magnet Yoke, with drift tubes and resitive-plate chambers in the barrel region.

Image File history File links Size of this preview: 800 × 533 pixelsFull resolution (3072 × 2048 pixel, file size: 2. ... Image File history File links Size of this preview: 800 × 533 pixelsFull resolution (3072 × 2048 pixel, file size: 2. ... Image File history File links Size of this preview: 380 × 599 pixelsFull resolution (2022 × 3189 pixel, file size: 1. ... Image File history File links Size of this preview: 380 × 599 pixelsFull resolution (2022 × 3189 pixel, file size: 1. ...

Collecting and collating the data

Pattern recognition

Testing the data read-out electronics for the tracker.
Testing the data read-out electronics for the tracker.

New particles discovered in CMS will be typically unstable and rapidly transform into a cascade of lighter, more stable and better understood particles. Particles travelling through CMS leave behind characteristic patterns, or ‘signatures’, in the different layers, allowing them to be identified. The presence (or not) of any new particles can then be inferred. Image File history File links Metadata Size of this preview: 398 × 599 pixelsFull resolution (2848 × 4288 pixel, file size: 2. ... Image File history File links Metadata Size of this preview: 398 × 599 pixelsFull resolution (2848 × 4288 pixel, file size: 2. ... Many fundamental particles (including quarks and leptons) have finite lifetimes, after which they decay into lower-mass particles. ...


Trigger system

To have a good chance of producing a rare particle, such as a Higgs boson, the particle bunches in the LHC collide up to 40 million times a second. Particle signatures are analyzed by fast electronics to save (or ‘trigger on’) only those events (around 100 per second) most likely to show new physics, such as the Higgs particle decaying to four muons. This reduces the data rate to a manageable level. These events are stored for subsequent detailed analysis. The Higgs boson is a hypothetical massive scalar elementary particle predicted to exist by the Standard Model of particle physics. ... In the Standard Model of particle physics, a muon (Greek μείον = minus) is a semistable fundamental particle with negative electric charge and a spin of 1/2. ...


Data analysis

Physicists from around the world use cutting-edge computing techniques (such as the Grid) to sift through millions of events from CMS to produce data that could indicate the presence of new particles or phenomena. Grid computing is a phrase in distributed computing which can have several meanings: A local computer cluster which is like a grid because it is composed of multiple nodes. ...


Milestones

The insertion of the vacuum-tank, June 2002
The insertion of the vacuum-tank, June 2002
YE+2 descent into the cavern
YE+2 descent into the cavern
YE+1, a component of CMS weighing 1,270 tonnes, finishes its 100m descent into the CMS cavern, January 2007
YE+1, a component of CMS weighing 1,270 tonnes, finishes its 100m descent into the CMS cavern, January 2007

Image File history File linksMetadata Insertion_of_vac-tank_2. ... Image File history File linksMetadata Insertion_of_vac-tank_2. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links Size of this preview: 800 × 521 pixelsFull resolution (1531 × 997 pixel, file size: 1. ... Image File history File links Size of this preview: 800 × 521 pixelsFull resolution (1531 × 997 pixel, file size: 1. ...

Context

Another experiment called ATLAS, installed at another point on the LHC ring, is meant to do similar physics; the ATLAS and CMS collaborations may compete to make major discoveries. ATLAS experiment detector under construction in October 2004 in its experimental pit; the current status of construction can be seen here. ...


The Tevatron is a proton - antiproton collider at Fermilab, with a center-of-mass energy of about 2 TeV. It has been operating since 1987. There are two experiments on the Tevatron ring called CDF and D0. Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... Aerial view of the Fermilab site. ... The Collider Detector at Fermilab (CDF) experimental collaboration studies high energy particle collisions at the Tevatron, the world’s highest energy particle accelerator. ... D0 under construction, the installation of the central tracking system D0s control room The D0 experiment consists of a worldwide collaboration of scientists conducting research on the fundamental nature of matter. ...


References

External links


  Results from FactBites:
 
CERN Courier - CMS assembly enters its next - IOP Publishing - article (415 words)
The return yoke for the detector's 4 T superconducting solenoid is now completely assembled, with a central section supporting the 7.6 m diameter, 13 m long outer shell of the solenoid's vacuum tank.
Barrel and endcap muon chambers were successfully installed during the summer, and a dry run of the solenoid coil insertion was also recently conducted.
Muon chamber supports on the 15 m diameter endcap yoke disks, for example, are positioned to an accuracy of 0.2 mm.
  More results at FactBites »

 
 

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