ALICE Time of Flight Module
The Time-Of-Flight system of ALICE consists of 90 such modules, each containing 15 or 19 Multigap Resistive Plate Chamber (MRPC) strips. This detector is used for identification of charged particles. It measures with high precision (50 ps) the time of flight of charged particles and therefore their velocity. The curvature of the particle trajectory inside the magnetic field gives the momentum, thus the particle mass is calculated and the particle is identified The MRPC is a stack of resistive glass plates, separated from each other by nylon fishing line. The mass production of the chambers (~1600, covering a surface of 150 m2) was done at INFN Bologna, while the first prototypes were bult at CERN.
DE;
LHC;
ALICE ;
Museum Heritage Collection ;
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Imported from Invenio.
Slice through an LHC bending magnet
Slice through an LHC superconducting dipole (bending) magnet. The slice includes a cut through the magnet wiring (niobium titanium), the beampipe and the steel magnet yokes. Particle beams in the Large Hadron Collider (LHC) have the same energy as a high-speed train, squeezed ready for collision into a space narrower than a human hair. Huge forces are needed to control them. Dipole magnets (2 poles) are used to bend the paths of the protons around the 27 km ring. Quadrupole magnets (4 poles) focus the proton beams and squeeze them so that more particles collide when the beams’ paths cross. There are 1232 15m long dipole magnets in the LHC.
LHC;
AC;
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http://cds.cern.ch/record/2284290/files/AC41.jpg?subformat=icon-180;
http://cds.cern.ch/record/2284290/files/AC41.gif?subformat=icon;
Imported from Invenio.
Slice through an LHC focusing magnet
Slice through an LHC superconducting quadrupole (focusing) magnet. The slice includes a cut through the magnet wiring (niobium titanium), the beampipe and the steel magnet yokes. Particle beams in the Large Hadron Collider (LHC) have the same energy as a high-speed train, squeezed ready for collision into a space narrower than a human hair. Huge forces are needed to control them. Dipole magnets (2 poles) are used to bend the paths of the protons around the 27 km ring. Quadrupole magnets (4 poles) focus the proton beams and squeeze them so that more particles collide when the beams’ paths cross. Bringing beams into collision requires a precision comparable to making two knitting needles collide, launched from either side of the Atlantic Ocean.
LHC ;
AC;
http://cds.cern.ch/record/2284291/files/AC42.JPG;
http://cds.cern.ch/record/2284291/files/AC42.jpg?subformat=icon-180;
http://cds.cern.ch/record/2284291/files/AC42.gif?subformat=icon;
Imported from Invenio.
LHC bending magnet coil
A short test version of coil of wire used for the LHC dipole magnets. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9’000 niobium–titanium filaments ten times finer than a hair.
LHC;
AC;
http://cds.cern.ch/record/2284292/files/AC43a.jpg;
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http://cds.cern.ch/record/2284292/files/AC43b.jpg?subformat=icon-180;
http://cds.cern.ch/record/2284292/files/AC43b.gif?subformat=icon;
Imported from Invenio.
Slice of LHC dipole wiring
More about LHC magnets
Dipole model slice made in 1994 by Ansaldo. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. 50’000 tonnes of steel sheets are used to make the magnet yokes that keep the wiring firmly in place. The yokes constitute approximately 80% of the accelerator's weight and, placed side by side, stretch over 20 km!
AC;
LHC;
Museum Heritage Collection ;
http://cds.cern.ch/record/2284293/files/AC45.JPG;
http://cds.cern.ch/record/2284293/files/AC45.jpg?subformat=icon-180;
http://cds.cern.ch/record/2284293/files/AC45.gif?subformat=icon;
Imported from Invenio.
LHC magnet support post
A prototype magnet support for the Large Hadron Collider (LHC). The magnet supports have to bridge a difference in temperature of 300 degrees. Electrical connections, instrumentation and the posts on which the magnets stand are the only points where heat transfer can happen through conduction. They are all carefully designed to draw off heat progressively. The posts are made of 4 mm thick glass-fibre– epoxy composite material. Each post supports 10 000 kg of magnet and leaks just 0.1 W of heat. This piece required a long development period which started in the early ’90s and continued until the end of the decade. The wires next to the support post are wires from strain gauges, which are employed to measure the stress level in the material when the support is mechanically loaded. These supports are mechanically optimized to withstand a weight of up to 100Kn (10 tons) while being as thin as possible to minimize conduction heat to magnets. This is the reason why the stress measurement was extensively done in the prototyping phase.
AC;
LHC;
Museum Heritage Collection ;
1995
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http://cds.cern.ch/record/2266136/files/AC47.png?subformat=icon-180;
Imported from Invenio.
Sample of superconducting wiring from the LHC
CERN article "The magic of superconductors in the spotlight"
The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9’000 niobium–titanium filaments ten times finer than a hair. The cables carry up to 12’500 amps and must withstand enormous electromagnetic forces. At full field, the force on one metre of magnet is comparable to the weight of a jumbo jet. Coil winding requires great care to prevent movements as the field changes. Friction can create hot spots which “quench” the magnet and ruin its superconductivity. A quench in any of the LHC superconducting magnets would stop machine operation. 50’000 tonnes of steel sheets are used to make the magnet yokes that keep the wiring firmly in place. The yokes constitute approximately 80% of the accelerator's weight and, placed side by side, stretch over 20 km!
AC;
LHC ;
Museum Heritage Collection ;
http://cds.cern.ch/record/2285237/files/AC049.JPG;
http://cds.cern.ch/record/2285237/files/Nb-Ti filaments .png;
http://cds.cern.ch/record/2285237/files/Nb-Ti Cable Cross section.jpg;
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http://cds.cern.ch/record/2285237/files/Nb-Ti Cable Cross section.jpg?subformat=icon-180;
http://cds.cern.ch/record/2285237/files/Nb-Ti Cable Cross section.gif?subformat=icon;
Imported from Invenio.
Section of LHC beampipe
About LHC as a vacuum system
A short section of the LHC beampipe including beam screen. Particle beams circulate for around 10 hours in the Large Hadron Collider (LHC). During this time, the particles make four hundred million revolutions of the machine, travelling a distance equivalent to the diameter of the solar system. The beams must travel in a pipe which is emptied of air, to avoid collisions between the particles and air molecules (which are considerably bigger than protons). The beam pipes are pumped down to an air pressure similar to that on the surface of the moon. Emptying the air from the two 27 km long Large Hadron Collider beam-pipes is equivalent in volume to emptying the nave of the Notre Dame cathedral in Paris. Initially, the air pressure is reduced by pumping. Then, cold sections of the beam-pipe are further emptied using the temperature gradient across special beam-screens inside the tube where particles travel. The warm sections are emptied using a coating called a getter that works like molecular fly-paper. This vacuum technology has applications in high performance solar panels. More technical information: In the LHC, particles circulate under vacuum. The vacuum chamber can be at room temperature (for example, in the experimental areas), or at cryogenic temperature, in the superconductive magnets. This piece is located in the superconductive magnets. The outer pipe is the vacuum chamber, which is in contact with the magnets, at cryogenic temperature (1.9K). It is called the “cold bore”. The inner tube is the beam screen. Its main goal is to protect the magnets from the heat load coming from the synchrotron radiation. Indeed, when high energy protons’ trajectory is bent, photons are emitted by the beam. They are intercepted by the beam screen. The temperature of the beam screen is kept between 5 and 20K by a circulation of gaseous helium in the small pipes on both sides of the beam screen. As those surfaces are at cryogenic temperature. The residual gas present in the accelerator is sticking on the surfaces. This phenomenon called “adsorption” is used to maintain a very low pressure in the vacuum chamber of the accelerator. About materials: The cold bore is in stainless steel. The beam screen is in stainless steel with colaminated copper. Both those material have a low outgassing rates, which means that they release few molecules in the vacuum chamber. About beam and impedance: The goal of the copper, which has a good electrical conductivity, is to facilitate the circulation of the image current. The beam is composed of charged particules circulating: it is an electric current. When it is circulating, an image current is produced. It is called induction. If the image current cannot circulate properly, the beam is slowed down. About adsorption process: When the beam circulates, photons from synchrotron radiation are emitted and hit the beam screen. By doing so, they desorb molecules from the walls. The molecules are then pumped down on the outer pipe (where they cannot be reached by the photons anymore), through the small holes in the beam screen.
AC;
LHC;
2009
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http://cds.cern.ch/record/2253707/files/AC60.jpg?subformat=icon-180;
http://cds.cern.ch/record/2253707/files/AC60.gif?subformat=icon;
Imported from Invenio.
Niobium Titanium and Copper wire samples
Two wire samples, both for carrying 13'000Amperes. I sample is copper. The other is the Niobium Titanium wiring used in the LHC magnets. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9’000 niobium–titanium filaments ten times finer than a hair. The cables carry up to 12’500 amps and must withstand enormous electromagnetic forces. At full field, the force on one metre of magnet is comparable to the weight of a jumbo jet. Coil winding requires great care to prevent movements as the field changes. Friction can create hot spots which “quench” the magnet and ruin its superconductivity. A quench in any of the LHC superconducting magnets would stop machine operation. 50’000 tonnes of steel sheets are used to make the magnet yokes that keep the wiring firmly in place. The yokes constitute approximately 80% of the accelerator's weight and, placed side by side, stretch over 20 km!
AC;
LHC;
2009
http://cds.cern.ch/record/2253655/files/AC48.jpg;
http://cds.cern.ch/record/2253655/files/AC48b.jpg;
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http://cds.cern.ch/record/2253655/files/AC48b.gif?subformat=icon;
http://cds.cern.ch/record/2253655/files/AC48b.jpg?subformat=icon-180;
Imported from Invenio.
LHC accelerating cavity prototype
More about radiofrequency cavities
Particles are accelerated using radio-frequency cavities. These contain an electric field which oscillates at just the right frequency to give a kick to the charged particles passing through.
AC;
LHC;
http://cds.cern.ch/record/2289743/files/LHC accelerating cavity prototype (i).JPG;
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http://cds.cern.ch/record/2289743/files/LHC accelerating cavity prototype (ii).gif?subformat=icon;
Imported from Invenio.
LHC beampipe interconnection
Particle beams circulate for around 10 hours in the Large Hadron Collider (LHC). During this time, the particles make four hundred million revolutions of the machine, travelling a distance equivalent to the diameter of the solar system. The beams must travel in a pipe which is emptied of air, to avoid collisions between the particles and air molecules (which are considerably bigger than protons). The beam pipes are pumped down to an air pressure similar to that on the surface of the moon. Much of the LHC runs at 1.9 degrees above absolute zero. When material is cooled, it contracts. The interconnections must absorb this contraction whilst maintaining electrical connectivity.
AC;
LHC;
Museum Heritage Collection ;
http://cds.cern.ch/record/2289744/files/AC065.jpg;
http://cds.cern.ch/record/2289744/files/AC065.jpg?subformat=icon-180;
http://cds.cern.ch/record/2289744/files/AC065.gif?subformat=icon;
Imported from Invenio.
ATLAS muon detector
Muon detectors from the outer layer of the ATLAS experiment at the Large Hadron Collider. Over a million individual detectors combine to make up the outer layer of ATLAS. All of this is exclusively to track the muons, the only detectable particles to make it out so far from the collision point. How the muon’s path curves in the magnetic field depends on how fast it is travelling. A fast muon curves only a very little, a slower one curves a lot. Together with the calorimeters, the muon detectors play an essential role in deciding which collisions to store and which to ignore. Certain signals from muons are a sure sign of exciting discoveries. To make sure the data from these collisions is not lost, some of the muon detectors react very quickly and trigger the electronics to record. The other detectors take a little longer, but are much more precise. Their job is to measure exactly where the muons have passed, calculating the curvature of their tracks in the magnetic field to the nearest five hundredths of a millimetre. Even these precision detectors are not exactly sluggish – they react within a millionth of a second. Such a fast response is essential when new collisions are occurring in the centre of ATLAS 40 million times every second! This muon detector is a drift tube - an aluminium tube with a wall thickness of some 1/10 mm that is filled with a special gas mixture. Inside the tube there is a wire that is tightened all over the length of the tube and fixed at the end caps. Particles (or ionizing radiation) that enter the tube ionize the gas molecules and liberate electrons. Since there is a high voltage between the wire and the tube wall, the released negatively charged electrons move towards the wire in the centre of the tube. On their way to the central wire, the moving electrons induce an electric signal that can be amplified and registered by further electronics.
DE;
LHC;
ATLAS;
Muon ;
detector;
Museum Heritage Collection ;
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http://cds.cern.ch/record/2264550/files/DE73b.gif?subformat=icon;
Imported from Invenio.
ATLAS Liquid Argon Calorimeter 2m prototype
This module was built and tested with beam to validate the ATLAS electromagnetic calorimeter design. One original design feature is the folding. 10 000 lead plates and electrodes are folded into an accordion shape and immersed in liquid argon. As they cross the folds, particles are slowed down by the lead. As they collide with the lead atoms, electrons and photons are ejected. There is a knock-on effect and as they continue on into the argon, a whole shower is produced. The electrodes collect up all the electrons and this signal gives a measurement of the energy of the initial particle. This 2 m long module dates back to the first detector studies for the LHC in the 1990’s. It was built by the R&D collaboration RD-3 to evaluate the performances of liquid argon calorimetry for the physics programme - the search for the Higgs boson decays into two photons, in particular. After the choice of that technology by the ATLAS collaboration, the design of its elements were reassessed in view of production and a new module was tested in the CERN beam lines, leading to the Technical Design Report in 1996.
DE ; LHC ; ATLAS ; Calorimeter ; Calorimetre ; Museum Heritage Collection ;
1990
http://cds.cern.ch/record/2254084/files/DE113.JPG;
http://cds.cern.ch/record/2254084/files/Photo of the module taken in 2018.jpg;
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http://cds.cern.ch/record/2254084/files/Photo of the module taken in 2018.jpg?subformat=icon-180;
Imported from Invenio.
CMS Tracker Model
Access to the pictures
Model of the tracking detector for the CMS experiment at the LHC. This object is a mock-up of an early design of the CMS Tracker mechanics. It is a segment of a “Wheel” to support Micro-Strip Gas Chamber (MSGC) detector modules on the outer layers and silicon-strip detector modules in the innermost layers. The particularity of that design is that modules are organised in spirals, along which power and optical cables and cooling pipes were planned to be routed. Some of such spirals are illustrated in the mock-up by the colors of the modules. With the detector development it became, however, evident that the silicon detectors would need to be operated in LHC experiments in cold temperatures, while the MSGC could stay in normal room-temperature. That split in two temperatures lead to separating those two detector types by a thermal barrier and therefore jeopardizing the idea of using common, vertical Wheels with services arranged along spirals.
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LHC ;
Museum Heritage Collection ;
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Imported from Invenio.
ATLAS Transition Radiation Tracker - small piece
Description of the ATLAS inner detector
The ATLAS transition radiation tracker is made of 300'000 straw tubes, up to 144cm long. Filled with a gas mixture and threaded with a wire, each straw is a complete mini-detector in its own right. An electric field is applied between the wire and the outside wall of the straw. As particles pass through, they collide with atoms in the gas, knocking out electrons. The avalanche of electrons is detected as an electrical signal on the wire in the centre. The tracker plays two important roles. Firstly, it makes more position measurements, giving more dots for the computers to join up to recreate the particle tracks. Also, together with the ATLAS calorimeters, it distinguishes between different types of particles depending on whether they emit radiation as they make the transition from the surrounding foil into the straws.
DE;
LHC;
2006
http://cds.cern.ch/record/2235799/files/ATLAS TRT.JPG;
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http://cds.cern.ch/record/2235799/files/ATLAS TRT.gif?subformat=icon;
Imported from Invenio.