About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC will be the largest superconducting installation ever built and, at 1.9 degrees above absolute zero (300 degrees below room temperature), one of the the coldest objects in the universe! Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9000 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.
About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC will be the largest superconducting installation ever built and, at 1.9 degrees above absolute zero (300 degrees below room temperature), one of the the coldest objects in the universe! Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9000 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.
Rock samples taken from 0 to 170 m below ground on the CERN site when the LEP (Large Electron Positron collider) pit number 6 was drilled in Bois-chatton (Versonnex). The challenges of LHC civil engineering: A mosaic of works, structures and workers of differents crafts and origins. Three consulting consortia for the engineering and the follow-up of the works. Four industrial consortia for doing the job. A young team of 25 CERN staff, 30 surface buildings, 32 caverns of all sizes, 170 000 m3 of concrete, 420 000 m3 excavated. 1998-2004 : six years of work and 340 millions Swiss Francs.
A wooden model of the ALEPH experiment and its cavern. ALEPH was one of 4 experiments at CERN's 27km Large Electron Positron collider (LEP) that ran from 1989 to 2000. During 11 years of research, LEP's experiments provided a detailed study of the electroweak interaction. Measurements performed at LEP also proved that there are three – and only three – generations of particles of matter. LEP was closed down on 2 November 2000 to make way for the construction of the Large Hadron Collider in the same tunnel. The cavern and detector are in separate locations - the cavern is stored at CERN and the detector is temporarily on display in Glasgow physics department. Both are available for loan.
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.
One of the building blocks of the CMS Silicon Tracker: a part of the detector that reconstructs the trajectories of charge particles emerging from the proton-proton collisions. A lightweight structure, made mostly of carbon fibre, supports silicon detectors and their readout electronics. These detectors generate an electrical pulse when they are traversed by a charged particle, and they are segmented into fine strips (in this case the strips are 180 microns wide, about the size of a human hair) that collect those pulses, such that the position of the strip provides a coordinate on the particle trajectory.
The crystals used in CMS’s electromagnetic calorimeter may look like simple bricks of glass, but they are in fact mostly metal and are heavier than steel! Lead tungstate crystal with a touch of oxygen in this crystalline form is highly transparent and scintillates when electrons and photons pass through it. This means it produces light in proportion to the particle’s energy. CMS contains nearly 80’000 such crystals, each of which took two days to grow. This technology developed at CERN has applications in medical imaging, for example improving cancer diagnosis. The Compact Muon Solenoid (CMS) is a general-purpose detector at the Large Hadron Collider (LHC).
The first layer of the ATLAS detector’s calorimeter is made of 8’200 lead plates and electrodes folded into an accordion shape and immersed in liquid argon. ATLAS (A Toroidal LHC ApparatuS) is the largest, general-purpose particle detector experiment at the Large Hadron Collider (LHC). As particles cross the folds and interact 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 of secondary particles is produced. The electrodes register a signal that gives a measurement of the energy of the initial particle. As with most of the LHC detectors, the structural design challenge is to hold the heavy elements in place without affecting the measurements of the particles. Here, the layers of honeycomb spacer are designed to do just that. They separate the copper electrode layer from the lead and stainless steel absorber, allowing the liquid argon to flow freely in between.
Each MCS magnet consists of six coils, a laminated iron yoke, an aluminium shrinking cylinder, an end plate that houses the electrical connections and an iron magnetic shield. The coils are made by counter-winding a single, rectangular cross-section, NbTi wire around a G11 central post. The superconductor has a rectangular cross-section and is enamel insulated. The coils are wet wound. After winding G11 end spacers are fitted to the ends of the coils which are then cured. The cured coils are assembled on a precise mandrel together with the connection plate, wrapped with a glass-fibre/epoxy pre-preg bandage and cured to make an MCS coil assembly. The MCS magnet module is built by stacking the eccentric yoke laminations [1] around the MCS coil assembly in 6 different azimuthal orientations and shrink fitting the aluminium shrinking cylinder. The radial interference between the inner diameter of the shrinking cylinder and the outer diameter of the yoke lamination stack is chosen such that the correct pre-stress is produced at operating temperature. This interference is obtained by precise machining of the cured coil assembly outer diameter. Precise dowel holes in the end plate allow accurate placement of the magnet module within the magnetic shield. The magnets are mounted on their support plate in the dipole cold mass by means of a bolted flange, this flange contains a pair of accurately drilled 6H7 holes for doweling to the support plate. Coil inter-connections are made by ultrasonic welding. Quench protection resistors are connected in parallel with each magnet and mounted in the gap between the shrinking cylinder and magnetic shield. [1] A. Ijspeert, J. Salminen, “Superconducting coil compression by scissor laminations”, EPAC-96, Sitges, Spain, June 1996.
Radioactive nuclei are produced at the ISOLDE facility by shooting a high-energy beam of protons on a thick target. By studying some of these nuclei, physicists are improving the knowledge of nucleosynthesis, the process through which stars produce chemical elements. This is a prototype that was developed for the CERN Open Days, in 2019.