The CMS experiment (Compact Muon Solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T ...superconducting magnet with 6 m diameter by 12.5 m long free bore, enclosed inside a 10000 ton return yoke. The magnetic field is achieved by a 4-layer superconducting solenoid made of a reinforced Rutherford type superconductor with a hybrid configuration and wound inside an external aluminum cylinder. The coil is indirectly cooled at an operating temperature of 4.5 K by a thermosiphon, and it is designed to run at a nominal current of 20 kA. The corresponding maximum stored magnetic energy reaches 2.6 GJ with an E/M ratio of 12 kJ/kg. The quench protection is achieved by discharging the magnet in an external resistor in fast mode, with a peak voltage in the coil kept at 600 V and a voltage to ground of plusmn300 V during the discharge. The coil design takes benefit of the quench back effect to limit the temperature gradients inside the winding pack in case of quench. The design and the characteristics of the quench protection system are described. The computational results of the quench protection for several operating currents are presented. The behavior of the magnet in case of faulty conditions on the protection system is analyzed
Mechanical properties of the CMS conductor Cure, B.; Blau, B.; Herve, A. ...
IEEE transactions on applied superconductivity,
06/2004, Letnik:
14, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
CMS (Compact Muon Solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting ...solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10000 ton return yoke. The magnetic field is achieved by a 4-layer superconducting solenoid made of a high purity aluminum (HPA) stabilized Rutherford type superconductor. The magnet is operated at 4.5 K, with a nominal current of 20 kA, for a total stored magnetic energy of 2.7 GJ. Due to the high magnetic forces at nominal field inside the winding pack, the structural component is the conductor itself to get a self-supporting winding structure. The mechanical reinforcement is made from aluminum alloy directly welded to the superconductor by electron beam (EB) welding technology before the winding operation. The external support cylinders also take part to the mechanical integrity. At each step of fabrication of the CMS conductor, the mechanical properties of the components and bonding between them are measured by destructive testing on short samples, in complement of continuous monitoring during production. This paper presents the results of the superconducting cable to pure aluminum shear testing, the tensile testing of the EN AW 6082 aluminum reinforcement, the insert to reinforcement shear testing, and the tensile testing of the full conductor before and after heat treatment induced during coil curing. Possible influence of the EB welding on the mechanical properties of the final conductor is investigated. Residual resistivity ratio (RRR) measurements of the HPA stabilizer are presented. Mechanical properties and equivalent RRR of the CMS conductor are presented for comparison with conductors of other geometry.
Compact muon solenoid (CMS) is a general-purpose detector designed to run at the highest luminosity at the CERN large hadron collider (LHC). Its distinctive features include a 4 T superconducting ...solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10000-ton return yoke made of construction steel. Accurate characterization of the magnetic field everywhere in the CMS detector, including the large ferromagnetic parts of the yoke, is required. To measure the field in and around ferromagnetic parts, a set of flux-loops and Hall probe sensors will be installed on several of the steel pieces. Fast discharges of the solenoid during system commissioning tests will be used to induce voltages in the flux-loops that can be integrated to measure the flux in the steel at full excitation of the solenoid. The Hall sensors will give supplementary information on the axial magnetic field and permit estimation of the remanent field in the steel after the fast discharge. An experimental R&D program has been undertaken, using a test flux-loop, two Hall sensors, and sample disks made from the same construction steel used for the CMS magnet yoke. A sample disc, assembled with the test flux-loop and the Hall sensors, was inserted between the pole tips of a dipole electromagnet equipped with a computer-controlled power supply to measure the excitation of the steel from full saturation to zero field. The results of the measurements are presented and discussed.
The conceptual design study of a Future Circular hadron-hadron Collider (FCC-hh) with a center-of-mass energy of the order of 100 TeV, assumed to be constructed in a new tunnel of 80–100 km ...circumference, includes the determination of the basic requirements for its detectors. A superconducting solenoid magnet of a 12-m-diameter inner bore with a central magnetic flux density of 6 T, in combination with two superconducting dipole magnets and two conventional toroid magnets, is proposed for an FCC-hh experimental setup. The coil of 23.468 m length has seven 3.35-m-long modules included into one cryostat. The steel yoke with a mass of 22.6 kt consists of two barrel layers of 0.5 m radial thickness and a 0.7-m-thick nose disk and four 0.6-m-thick endcap disks each side. The outer diameter of the yoke is 17.7 m. The full length of the magnetic system is 62.6 m. The air gaps between the endcap disks provide for the installation of muon chambers up to an absolute pseudorapidity of about 2.7. The superconducting dipole magnets provide measurement of charged particle momenta in the absolute pseudorapidity region greater than 3. The conventional forward muon spectrometer allows muon identification in the absolute pseudorapidity region from 2.7 to 5. The magnet is modeled with the program TOSCA from Cobham CTS Limited. The total current in the superconducting solenoid coil is 123 MA turns; the stored energy is 41.8 GJ. The axial force acting on each endcap is 450 MN. The stray field is 13.7 mT at a radius of 50 m from the coil axis and 5.2 mT at a radius of 100 m. Many other parameters are presented and discussed.
Magnetic Tests of the CMS Superconducting Magnet Kircher, F.; Bredy, P.; Fazilleau, P. ...
IEEE transactions on applied superconductivity,
06/2008, Letnik:
18, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
The superconducting magnet for CMS has been designed to reach a 4 T field in a free bore of 6 m over a length of 12.5 m, with a stored energy of 2.6 GJ at nominal current. The magnet has been ...extensively and successfully tested in a surface hall at CERN in August and October 2006. Its characteristics make it the largest superconducting solenoid ever built in terms of bending power for the physics, stored energy and stored energy per unit of cold mass. The tests of the magnet were carried out by charging it to progressively higher currents. Long current flattops were used for magnetic measurements, generally ending with triggered fast discharges. During the tests, all the relevant parameters related to electrical, magnetic, thermal and mechanical behavior have been recorded and will be reported in the paper. Special emphasis will be put on the results and analysis of phenomena related to induced fast discharges, such as coupling and quench-back effects.
The CMS experiment (Compact Muon Solenoid) is a general-purpose proton-proton detector designed to run at the highest luminosity at the LHC. Distinctive features of the CMS detector include a ...high-magnetic-field solenoid (4T) coupled with a multilayer muon system, a fully active scintillating-crystal electromagnetic calorimeter, a tile hadronic calorimeter, and a powerful inner tracking system. The two 20 kA current leads for the CMS electrical circuit have been designed, manufactured and tested by CEA Saclay. Their design, with reliability as prime goal, is based on the use of a pure-copper braid, having an RRR of 130, placed inside a conduit and cooled by evaporating helium gas. Their length is of 3.3 m to cross the return yoke and their conductive cross-section has been fixed at 1800 mm/sup 2/, slightly above the optimal section. An important specification is the behavior in case of lack of coolant: the current leads are able to hold the maximal current during 5 minutes followed by a fast discharge, time constant of 190 s, without any damage. They are fully instrumented with sensors and diagnostics (temperature, voltage and helium flow) for safety and control. In case of discharge, they are submitted to a high voltage and then must ensure an insulation of 3 kV. The tests will include insulation, mechanical and electrical tests (at nominal current, with and without coolant).
The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4 T, the magnetic length is ...12.5 m and the free bore is 6 m. The coil is wound from 20 high purity aluminum-stabilized NbTi conductors with a total length of 45 km. The main peculiarity of the CMS magnet among other existing thin detector solenoids is its sandwich-type aluminum-stabilized superconductor. This special feature was chosen in order to have a mechanically self-supporting winding structure. We measured the critical current of all the 21 finished conductors in fields up to 6 T using the Ma.Ri.S.A. test facility at INFN-Genova. We compare these results with the critical current of single strands measured by CEA-Saclay, extracted from the conductor after the co-extrusion. A comparison among the measurements provides information about the possible critical current degradation and assures an accurate quality control of the conductor production. We also qualified the method used for making the joints between the layers within a single module and between the five modules and the bus bars. Measurements on both round and straight TIG-welded samples were carried out, in Genova and at CEA-Saclay, respectively.
Flux loops and Hall probes are being installed on selected segments of the steel flux return of the 4 T solenoid of the compact muon solenoid (CMS) detector under construction at CERN (European ...Center for Nuclear Research). This steel also serves as part of the muon detection system of CMS and accurate characterization of the magnetic flux density in the steel as elsewhere in the detector is required. Voltages induced in the flux loops during fast discharge of the solenoid will be sampled and integrated to measure the change in average flux density in the steel during the discharge. Hall probes mounted on the surface of the steel segments will provide information about the fields internal and external to the steel. In the laboratory work reported herein small iron discs with flux loops on their peripheries and Hall probes on their flat surfaces are magnetized between the pole tips of a laboratory standard magnet and controlled power supply. The voltages induced in the flux loops during charging and discharging of the magnet are integrated and compared with the Hall probes which sample the fields immediately external to the discs. The experimental work reported here will provide interpretation of the flux coil and Hall probe measurements from the CMS magnet when it is commissioned in 2005.
Validation of the CMS Magnetic Field Map Klyukhin, V. I.; Amapane, N.; Ball, A. ...
Journal of superconductivity and novel magnetism,
02/2015, Letnik:
28, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Compact Muon Solenoid (CMS) is a general purpose detector, designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4-T ...superconducting solenoid with 6-m-diameter by 12.5-m-length free bore, enclosed inside a 10,000-ton return yoke made of construction steel. The return yoke consists of five dodecagonal three-layered barrel wheels and four end-cap disks at each end comprised of steel blocks up to 620 mm thick, which serve as the absorber plates of the muon detection system. To measure the field in and around the steel, a system of 22 flux loops and 82 three-dimensional (3-D) Hall sensors is installed on the return yoke blocks. A TOSCA 3-D model of the CMS magnet is developed to describe the magnetic field everywhere outside the tracking volume measured with the field-mapping machine. The magnetic field description is compared with the measurements and discussed.
The Compact Muon Solenoid (CMS) is a general purpose detector, designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T ...superconducting solenoid with 6-m-diameter by 12.5-m-length free bore, enclosed inside a 10,000-ton return yoke made of construction steel. The return yoke consists of five dodecagonal three-layered barrel wheels and four end-cap disks at each end comprised of steel blocks up to 620 mm thick, which serve as the absorber plates of the muon detection system. Accurate characterization of the magnetic field everywhere in the CMS detector is required. To measure the field in and around the steel, a system of 22 flux loops and 82 3-D Hall sensors is installed on the return yoke blocks. Fast discharges of the solenoid (190 s time-constant) made during the CMS magnet surface commissioning test at the solenoid central fields of 2.64, 3.16, 3.68 and 4.01 T were used to induce voltages in the flux loops. The voltages are measured on-line and integrated off-line to obtain the magnetic flux in the steel yoke close to the muon chambers at full excitations of the solenoid. The 3-D Hall sensors installed on the steel–air interfaces give supplementary information on the components of magnetic field and permit to estimate the remanent field in steel to be added to the magnetic flux density obtained by the voltages integration. A TOSCA 3-D model of the CMS magnet is developed to describe the magnetic field everywhere outside the tracking volume measured with the field-mapping machine. The results of the measurements and calculations are presented, compared, and discussed.
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