doi:10.1109/TASC.2006.870503engVollinger, CTodesco, EIdentification of Assembly Faults through the Detection of Magnetic Field Anomalies in the Production of the LHC DipolesAccelerators and Storage RingsLHC-PROJECT-Report-905CERN-LHC-Project-Report-905Magnetic measurements at room temperature have been used to monitor the production of the superconducting coils of the Large Hadron Collider main dipoles. They have made it possible to identify several assembly errors, e.g. cases of bad gluing of the coil layers, bad conductor positioning, missing pole shims and other problems related to faulty procedures. This paper reviews the experience accumulated so far considering almost 1000 dipoles. After a short outline of the method used to pin out field anomalies and deduce realistic deformation of the coil, an exhaustive list of the cases met during the production is given. A discussion follows on the findings after decollaring as compared to the predictions, including the still open cases.2006-05-19http://cds.cern.ch/record/97040410.1109/TASC.2006.870503http://cds.cern.ch/record/970404oai:cds.cern.ch:970404 engFessia, PCanseco, IR3D FEM Modeling of the Coil Ends of the LHC Main DipoleAccelerators and Storage RingsLHC-PROJECT-Report-904CERN-LHC-Project-Report-904A 3D finite element mechanical model has been developed to simulate the complex geometry of the extremities of the coils for the LHC main dipoles. The final aim is to evaluate the possible impact of coil defects on quench performances. In this paper we describe the first part of the work that has been carried out. This covers an analysis of the contribution of the mechanical properties of the different materials to the rigidity of the coil heads and the experimental validation of the model. For such validation we compared the computed stiffness with the values observed during production measurements in industry. The numerical results are in good agreement with the measured; some discrepancies in the intermediate zone of the end point out also in which direction the modeling should be refined.2006-05-19http://cds.cern.ch/record/970403http://cds.cern.ch/record/970403oai:cds.cern.ch:970403 doi:10.1109/TASC.2006.871220engSanfilippo, SBeauquis, JBottura, LBuzio, MCoccoli, MGarcía-Pérez, JPugnat, PSammut, NSiemko, ASmirnov, NStafiniak, AWildner, EElectrical and Magnetic Performance of the LHC Short Straight SectionsAccelerators and Storage RingsLHC-PROJECT-Report-903CERN-LHC-Project-Report-903The Short Straight Section (SSS) for the Large Hadron Collider arcs, containing in a common cryostat the lattice quadrupoles and correction magnets, have now entered series production. The foremost features of the lattice quadrupole magnets are a two-in-one structure containing two 56 mm aperture, two-layers coils wound from 15.1 mm wide NbTi cables, enclosed by the stainless steel collars and ferromagnetic yoke, and inserted into the inertia tube. Systematic cryogenic tests are performed at CERN in order to qualify these magnets with respect to their cryogenic and electrical integrity, the quench performance and the field quality in all operating conditions. This paper reports the main results obtained during tests and measurements in superfluid helium. The electrical characteristics, the insulation measurements and the quench performance are compared to the specifications and expected performances for these magnets. The field in the main quadrupole is measured using three independent systems: 10-m long twin rotating coils, an automatic scanner, and single stretched wire. A particular emphasis is given to the integrated transfer function which has a spread of around 12 units rms in the production and is a critical issue. The do-decapole harmonic component, which required trimming through a change in coil shims, is also discussed. Finally, the magnetic axis measurements at room temperature and at 1.9 K, providing the nominal vertical shift for installation are reported.2006-05-19http://cds.cern.ch/record/97040110.1109/TASC.2006.871220http://cds.cern.ch/record/970401oai:cds.cern.ch:970401 engBajko, MChamizo, RCharrondiere, CKuzmin, ASavary, FThe LHC Dipole Geometry as Built in IndustryAccelerators and Storage RingsLHC-PROJECT-Report-902CERN-LHC-Project-Report-902The LHC dipoles magnets are produced in 5 industrial production sites in Europe. The production is well underway and more than half of the total quantity has been delivered to CERN. One of the important characteristics of the dipole magnets is their geometry. To achieve the requested mechanical tolerances on the magnets, which are 15 m long and have a 28 t mass, the final assembly operations includes precise optical measurements. To ensure the good quality and high production rate, the final assembly procedure has been automated as much as possible. The authors report here about the assembly procedure, the features of the software that guides the optical measurements (and consequently the assembly operations) and the results obtained on the geometry in the different sites.2006-05-19http://cds.cern.ch/record/970400http://cds.cern.ch/record/970400oai:cds.cern.ch:970400 engLeroy, DReview of the R&D and Supply of the LHC Superconducting CablesAccelerators and Storage RingsLHC-PROJECT-Report-901CERN-LHC-Project-Report-901The construction of the superconducting magnets for the LHC machine has required the supply of ~ 7350 km of superconducting cables. The delivery of cables which is completed at 97% has made use of a large part of the world wide production capacity. Ten contracts have been placed with firms in Europe, Japan, USA. The Nb-Ti and the Nb materials have been contracted by CERN. Before tendering and placing the contracts, a R&D program has combined studies at CERN and orders of finished cables of significant lengths to industry. The report will present the main results of the R&D program, the characteristics of the LHC cables, the encountered difficulties and the obtained successes during the long duration fabrication contracts of the highly sophisticated LHC superconducting cables.2006-05-19http://cds.cern.ch/record/970398http://cds.cern.ch/record/970398oai:cds.cern.ch:970398 engPrevitali, VBoutboul, TLe Naour, SLeroy, DOberli, LCritical Current Studies on Deformed Nb-Ti StrandsAccelerators and Storage RingsLHC-PROJECT-Report-900CERN-LHC-Project-Report-900The Nb-Ti hard conductors used in LHC dipole and quadrupole magnets are Rutherford cables composed of several tens of strands. During the cabling process, the strands are severely compacted especially at the thin edge of the cable. In order to assess, on the whole wire length, the deformation effect on the transport current of the wires, LHC-type Nb-Ti superconducting strands of various types were flattened by means of rollers. The critical current was then measured as a function of deformation and applied magnetic field at both 4.3 K and 1.9 K. The measurements were performed for both orientations (flat face perpendicular or parallel to magnetic field). The critical current density anisotropy of such deformed strands and the correlation with magnetization effects are discussed. This study permits to better understand and to quantify the critical current degradation of few percent observed in strands due to cabling. Comparisons with wires extracted from Rutherford cables are presented.2006-05-19http://cds.cern.ch/record/970397http://cds.cern.ch/record/970397oai:cds.cern.ch:970397 engCalvi, MAgrisani, LBottura, LMasi, ASiemko, AOn the Use of Wavelet Transform for Quench Precursors Characterisation in the LHC Superconducting Dipole MagnetsAccelerators and Storage RingsLHC-PROJECT-Report-899CERN-LHC-Project-Report-899Premature training quenches are caused by transient energy released within the magnet coil while it is energized. Signals recorded across the so-called quench antenna carry information about these disturbances. A new method for identifying and characterizing those events is proposed, which applies the wavelet transform approach to the recorded signals. Such an approach takes into account the time of occurrence as well as frequency content of the events. The choice of the optimal mother wavelet is discussed, and the results obtained from the application of the method to actual signals are given. The criteria to recognize the interesting events are presented as well as the methodology to classify their global behavior.2006-05-19http://cds.cern.ch/record/970396http://cds.cern.ch/record/970396oai:cds.cern.ch:970396 doi:10.1109/TASC.2006.8732engBertinelli, FComel, SHarlet, PPeiro, GRusso, ATaquet, AProduction of Low-Carbon Magnetic Steel for the LHC Superconducting Dipole and Quadrupole MagnetsAccelerators and Storage RingsLHC-PROJECT-Report-898CERN-LHC-Project-Report-898In 1996 CERN negotiated a contract with Cockerill Sambre – ARCELOR Group for the supply of 50 000 tonnes of low-carbon steel for the LHC main magnets: this was the first contract to be placed for the project, and one of the single largest. In 2005 – after nine years of work – the contract is being successfully completed. This paper describes the steel specifically developed, known as MAGNETIL™, its manufacturing and quality control process, organization of production, logistics and contract follow-up. Extensive statistics have been collected relating to physical, mechanical and technological parameters. Specific attention is dedicated to magnetic measurements (coercivity and permeability) performed at both room and cryogenic temperatures, the equipment used and statistical results. Reference is also made to the resulting precision of the fineblanked laminations used for the magnet yoke. The technology transfer from the particle accelerator domain to industry is ongoing, for example for the screening of high voltage cables buried in the ground.2006-05-19http://cds.cern.ch/record/97039510.1109/TASC.2006.8732http://cds.cern.ch/record/970395oai:cds.cern.ch:970395 engTortschanoff, TheodorBurgmer, RDurante, MHagen, PKlein, UKrischel, DPayn, ARossi, LSchellong, BSchmidt, PSimon, FSchirm, K-MTodesco, EThe LHC Main Quadrupoles during Series FabricationAccelerators and Storage RingsLHC-PROJECT-Report-897CERN-LHC-Project-Report-897By the end of August 2005 about 320 of the 400 main LHC quadrupole magnets have been fabricated and about 220 of them assembled into their cold masses, together with corrector magnets. About 130 of them have been cold tested in their cryostats and most of the quadrupoles exceeded their nominal excitation, i.e. 12,000 A, after no more than two training quenches. During this series fabrication, the quality of the magnets and cold masses was thoroughly monitored by means of warm magnetic field measurements, of strict geometrical checking, and of various electrical verifications. A number of modifications were introduced in order to improve the magnet fabrication, mainly correction of the coil geometry for achieving the specified field quality and measures for avoiding coil insulation problems. Further changes concern the electrical connectivity and insulation of instrumentation, and of the corrector magnets inside the cold masses. The contact resistances for the bus-bar connections to the quench protection diodes and the elimination of insulation problems of the main bus-bars required special attention. To this must be added actions for solving of interface problems to the neighbouring magnets in the machine and to the cryogenic feed line.2006-05-19http://cds.cern.ch/record/970394http://cds.cern.ch/record/970394oai:cds.cern.ch:970394 engCharifoulline, ZResidual Resistivity Ratio (RRR) Measurements of LHC Superconducting NbTi Cable StrandsAccelerators and Storage RingsLHC-PROJECT-Report-896CERN-LHC-Project-Report-896The Rutherford-type superconducting NbTi cables of the LHC accelerator are currently manufactured by six industrial companies. As a part of the acceptance tests, the Residual Resistivity Ratio (RRR) of superconducting strands is systematically measured on virgin strands to qualify the strands before cabling and on extracted strands to qualify the cables and to check the final heat treatment (controlled oxidation to control interstrand resistance). More than 12000 samples of virgin and extracted strands have been measured during last five years. Results show good correlation with the measurements done by the companies and reflect well the technological process of cable production (strand annealing, cabling, cable heat treatment). This paper presents a description of the RRR-test station and the measurement procedure, the summary of the results over all suppliers and finally the correlation between RRR-values of the cables and the magnets.2006-05-19http://cds.cern.ch/record/970393http://cds.cern.ch/record/970393oai:cds.cern.ch:970393 doi:10.1109/TASC.2006.870494engSeyvet, FArnau-Izquierdo, GBertarelli, ADenis, OEl-Kallassi, PFernández-Cano, E DFessia, PIlie, S DJeanneret, J BLetant, DPoncet, APugnat, PSavary, FSgobba, StefanoSiemko, ATodesco, ETommasini, DVeness, RVullierme, BWildner, ELong Term Stability of the LHC Superconducting Cryodipoles after Outdoor StorageAccelerators and Storage RingsLHC-PROJECT-Report-895CERN-LHC-Project-Report-895The main superconducting dipoles for the LHC are being stored outdoors for periods from a few weeks to several years after conditioning with dry nitrogen gas. Such a storage before installation in the 27 km circumference tunnel may affect not only the mechanical and cryogenic functionality of the cryodipoles but also their quench and field performance. A dedicated task force was established to study all aspects of long term behaviour of the stored cryodipoles, with particular emphasis on electrical and vacuum integrity, quench training behaviour, magnetic field quality, performance of the thermal insulation, mechanical stability of magnet shape and of the interface between cold mass and cryostat, degradation ofmaterials and welds. In particular, one specifically selected cryodipole stored outdoors for more than one year, was retested at cold. In addition, various tests have been carried out on the cryodipole assembly and on the most critical subcomponents to study aspects such as the hygrothermal behaviour of the supporting system and the possible oxidation of the Multi Layer Insulation reflective films. This paper summarizes the main investigations carried out and their results.2006-05-19http://cds.cern.ch/record/97039210.1109/TASC.2006.870494http://cds.cern.ch/record/970392oai:cds.cern.ch:970392 engMacCaferri, RBettoni, STommasini, DVenturini-Delsolaro, WManufacture and Test of the Prototype 5 T Superconducting Undulator for the LHC Synchrotron Radiation Profile MonitorAccelerators and Storage RingsLHC-PROJECT-Report-894CERN-LHC-Project-Report-894A superconducting undulator wound with Nb-Ti based conductor, will be used in the LHC as a key part of the synchrotron radiation profile monitor system. Two undulators are needed, one per each circulating beam, providing 5 T in a 60 mm bore over two periods of 280 mm each. A full scale prototype has been designed and successfully tested in the end of 2004. In this paper, the electromagnetic and the mechanical design of the undulator are summarized. The fabrication of the prototype is described and the successful cold test results, both power test and magnetic flux density measurements, are reported.2006-05-19http://cds.cern.ch/record/970391http://cds.cern.ch/record/970391oai:cds.cern.ch:970391 doi:10.1109/TASC.2006.870498engBertinelli, FBoter-Rebollo, EBerthollon-Vitte, SGlaude, DVanenkov, IA Correlation Study between Geometry of Collared Coils and Normal Quadrupole Multipole in the Main LHC DipolesAccelerators and Storage RingsLHC-PROJECT-Report-893CERN-LHC-Project-Report-893The quality control implemented at all LHC dipole assemblers includes precise mechanical measurements of the geometry of collared coils. A cross-analysis performed between mechanical and magnetic measurements data shows a correlation between collared coils outer dimensions and the normal quadrupole multipole (b2) for one dipole assembler. The profile geometry of the single collars - as determined from 3D measurements at the collar suppliers and CERN - could not account alone for the significant left – right aperture asymmetry observed. This triggered a deeper investigation on different elements of the geometry of single collars. The results of this work show that the relative positioning of the collaring holes, allowing a small bending deformation of collars under the effect of coil pre-stress, is an important effect that generates a b2 multipole at the limit of specification. The study has deepened the understanding of the factors affecting collared coil geometry and field quality. The precision of 3D measurements at the collar suppliers and at CERN has been improved, and a tighter quality control has been introduced at the collar suppliers.2006-05-19http://cds.cern.ch/record/97039010.1109/TASC.2006.870498http://cds.cern.ch/record/970390oai:cds.cern.ch:970390 doi:10.1109/TASC.2006.873244engBertinelli, FFudanoki, FKomori, TPeiro, GRossi, LProduction of Austenitic Steel for the LHC Superconducting Dipole MagnetsAccelerators and Storage RingsLHC-PROJECT-Report-892CERN-LHC-Project-Report-892The austenitic-steel collars are an important component of the LHC dipole magnets, operating at cryogenic temperature under high mechanical stress. The required steel, known as YUS 130S, has been specifically developed for this application by Nippon Steel Corporation (NSC), who was awarded a CERN contract in 1999 for the supply of 11 500 tonnes. In 2005 - after six years of work - the contract is being successfully completed, with final production being ensured since October 2003 by Nippon Steel & Sumikin Stainless Steel Corporation (NSSC). The paper describes the steel properties, its manufacturing and quality control process, organization of production, logistics and contract follow-up. Extensive statistics have been collected relating to mechanical, physical and technological parameters. Specific attention is dedicated to measurements of magnetic permeability performed at cryogenic temperatures by CERN, the equipment used and statistical results. Reference is also made to the resulting precision of the fineblanked collars.2006-05-19http://cds.cern.ch/record/97038910.1109/TASC.2006.873244http://cds.cern.ch/record/970389oai:cds.cern.ch:970389 doi:10.1109/TASC.2006.870507engWildner, EBeauquis, JLa China, MTommasini, DControl of the Dipole Cold Mass Geometry at CERN to Optimize LHC PerformanceAccelerators and Storage RingsLHC-PROJECT-Report-891CERN-LHC-Project-Report-891The detailed shape of the 15 m long superconducting LHC dipole cold mass is of high importance as it determines three key parameters: the beam aperture, nominally of the order of 10 beam standard deviations; the connectivity of the beam- and technical lines between magnets; the transverse position of non-linear correctors mounted on the dipole ends. An offset of the latter produces unwanted beam dynamics perturbations. The tolerances are in the order of mm over the length of the magnet. The natural flexibility of the dipole and its mechanical structure allow deformations during handling and transportation which exceed the tolerances. This paper presents the observed deformations of the geometry during handling and various operations at CERN, deformations which are interpreted thanks to a simple mechanical model. These observations have led to a strategy of dipole geometry control at CERN, based on adjustment of the position of its central support (the dipole is supported at three positions, horizontally and vertically) to recover individually or statistically their original shape as manufactured. The implementation of this strategy is discussed, with the goal of finding a compromise between conflicting requirements: quality of the dipole geometry, available resources for corrective actions and magnet installation strategy whereby the geometry tolerances depend on the final magnet position in the machine.2006-05-19http://cds.cern.ch/record/97038810.1109/TASC.2006.870507http://cds.cern.ch/record/970388oai:cds.cern.ch:970388 engFessia, PKrog-Pedersen, SRossi, LApplication of the Learning Curve Analysis to the LHC Main Dipole Production: First AssessmentAccelerators and Storage RingsLHC-PROJECT-Report-890CERN-LHC-Project-Report-890About two third of the LHC main dipoles have been delivered by the three suppliers charged of the production. The training of the staff, mostly hired just for this manufacture, and the natural improvement of the procedures with the acquired experience, decrease naturally the time necessary for the assembly of a unit. The aim of this paper is to apply methodologies like the cost-based learning curves and the time-based learning curves to the LHC Main Dipole comparing the estimated learning percentage to the ones experienced in other industries. This type of analysis, still in a preliminary phase and here applied to about 40% of the total production of the LHC magnets that will end by 2006, shows that our production has a relatively high learning percentage and it is similar to aerospace and complex machine tools for new models. Therefore with the LHC project, accelerator magnets seem to have reached industrial maturity and this production can be used as bench mark for other large scientific projects implying series production.2006-05-19http://cds.cern.ch/record/970387http://cds.cern.ch/record/970387oai:cds.cern.ch:970387 engVenturini-Delsolaro, WKarppinen, MCold Test Results of the Inner Triplet Orbit Correctors for the LHCAccelerators and Storage RingsLHC-PROJECT-Report-889CERN-LHC-Project-Report-889The inner triplet orbit correctors for the LHC, MCBX and MCBXA, underwent acceptance tests at superfluid helium temperature at CERN, before shipping to FNAL for integration in the cold masses. A total of 27 MCBX (Horizontal-Vertical Dipole Correctors), of which 9 MCBXA (with nested Sextupole-Dodecapole insert), are needed for the LHC, including spares. The paper discusses the test protocols for series magnets, and reports the results of quench performance and cold magnetic measurements. The peculiarities of combined training and the hysteresis effects in the nested windings are presented, together with the search of the optimum setting procedure to minimize the persistent current effects on the beam dynamics.2006-05-19http://cds.cern.ch/record/970386http://cds.cern.ch/record/970386oai:cds.cern.ch:970386 engSchwerg, NVöllinger, CDevelopment of a Current Fit Function for NbTi to be Used for Calculation of Persistent Current Induced Field Errors in the LHC Main DipolesAccelerators and Storage RingsLHC-PROJECT-Report-888CERN-LHC-Project-Report-888A new fit function for the critical current density of superconducting NbTi cables for the LHC main dipoles is presented. Existing fit functions usually show a good matching of the very low field range, but produce a current density which is significantly too small for the intermediate and high field range. Consequently the multipole range measured at cold is only partially reproduced and loops from current cycling do not match. The presented function is used as input for the field quality calculation of a complete magnet cross-section including arbitrary current cycling and all hysteresis effects. This way allows to trace a so-called finger-print of the cable combination used in the LHC main bending magnets. The finger-print pattern is a consequence of the differences of the measured superconductor magnetization of cables from different manufacturers. The simulation results have been compared with measurements at cold obtained from LHC main dipoles and a very good agreement for low and intermediate field values could be observed.2006-05-19http://cds.cern.ch/record/970384http://cds.cern.ch/record/970384oai:cds.cern.ch:970384 doi:10.1109/TASC.2006.870500engBellesia, BBertinelli, FSantoni, CTodesco, EDependence of Magnetic Field Quality on Collar Supplier and Dimensions in the Main LHC DipoleAccelerators and Storage RingsLHC-PROJECT-Report-887CERN-LHC-Project-Report-887In order to keep the electro-magnetic forces and to minimize conductor movements, the superconducting coils of the main Large Hadron Collider dipoles are held in place by means of austenitic steel collars. Two suppliers provide the collars necessary for the whole LHC production, which has now reached more than 800 collared coils. In this paper we first assess if the different collar suppliers origin a noticeable difference in the magnetic field quality measured at room temperature. We then analyze the measurements of the collar dimensions carried out at the manufacturers, comparing them to the geometrical tolerances. Finally we use a magneto-static model to evaluate the expected spread in the field components induced by the actual collar dimensions. These spreads are compared to the magnetic measurements at room temperature over the magnet production in order to identify if the collars, rather than other components or assembly process, can account for the measured magnetic field effects. It has been found that in one over the three Cold Mass Assemblers the driving mechanism of the magnetic field harmonics b2 and a3 is the collar shape.2006-05-19http://cds.cern.ch/record/97038210.1109/TASC.2006.870500http://cds.cern.ch/record/970382oai:cds.cern.ch:970382 engHagen, PBottura, LCalvi, MSanfilippo, SSchirm, KTodesco, ETortschanoff, TheodorSimon, FSteering the Field Quality in the Production of the Main Quadrupoles of the Large Hadron ColliderAccelerators and Storage RingsLHC-PROJECT-Report-886CERN-LHC-Project-Report-886The main issues concerning the field quality in the main quadrupoles of the Large Hadron Collider are presented. We show the trend plots for the focusing strength and multipoles at room temperature covering more than 2/3 of the production. We describe the correction of the coil layout to improve b6 at injection field level. A non-negligible fraction of the quadrupoles has been manufactured with collars featuring a magnetic permeability somewhat higher than the specified limits. We show plots for this anomaly. Field quality correlations to measurements in operational conditions are discussed. The dependence of field quality on cable manufacturer is analysed2006-05-19http://cds.cern.ch/record/970379http://cds.cern.ch/record/970379oai:cds.cern.ch:970379 doi:10.1109/TASC.2006.870777engBoutboul, TLe Naour, SLeroy, DOberli, LPrevitali, VCritical Current Density in Superconducting Nb-Ti Strands in the 100 mT to 11 T Applied Field RangeAccelerators and Storage RingsLHC-PROJECT-Report-885CERN-LHC-Project-Report-885The knowledge of the critical current density in a wide temperature and applied magnetic field range is a crucial issue for the design of a superconducting magnet, especially for determining both current and temperature margins. The critical current density of LHC-type Nb-Ti strands of 0.82 and 0.48 mm diameter was measured by means of critical current and magnetization measurements at both 4.2 K and 1.9 K and for a broad magnetic field range (up to 11 T). For the magnetic field range common to both measurement methods, critical current density values as extracted from transport current and from magnetization data are compared and found fairly consistent. Our experimental data are compared to other sets from literature and to scaling laws as well.2006-05-19http://cds.cern.ch/record/97037810.1109/TASC.2006.870777http://cds.cern.ch/record/970378oai:cds.cern.ch:970378 engPrin, HCanard, PCatalán Lasheras, NKirby, GOstojic, RPerez, JCProduction of the Superconducting Matching Quadrupoles for the LHC InsertionsAccelerators and Storage RingsLHC-PROJECT-Report-884CERN-LHC-Project-Report-884The LHC insertions are equipped with individually powered superconducting quadrupole assemblies comprising several quadrupole magnets and orbit correctors, and range in length from 5.3 m to 11.3 m. Following the initial experience in the assembly of the pre-series cold masses, the production has advanced well and about half of the total of 82 units has been produced at CERN. In this paper we present the experience gained in steering the cold mass production, in particular with respect to the alignment requirements. We also report on the field quality and other measurements made for assuring the quality of the quadrupoles.2006-05-19http://cds.cern.ch/record/970377http://cds.cern.ch/record/970377oai:cds.cern.ch:970377 engJacquemod, ABalaguer, J MLaurent, FTock, J PVaudaux, LQualification and Start of Production of the Ultrasonic Welding Machines for the LHC InterconnectionsAccelerators and Storage RingsLHC-PROJECT-Report-883CERN-LHC-Project-Report-883The Large Hadron Collider (LHC) is presently under installation at CERN, Geneva. The approximately 4000 superconducting corrector magnets required by the machine are powered through copper-stabilized Nb-Ti busbars. To interconnect the magnets along the machine, about 50 000 joints between superconducting cables rated at 600 A have to be performed in-situ during the interconnection activities. An ultrasonic welding technique has been developed and optimised by CERN which led to the development of a dedicated machine which was qualified during the assembly of the STRING II, a 110-m chain of cryomagnets assembled as a prototype of the LHC. The realization of the â series â interconnections together with the procurement of the tooling based on functional specifications have been contracted to a consortium of firms. Qualification tests and acceptance criteria in terms of electrical contact resistance, mechanical resistance, reliability and reproducibility have been defined by CERN. This paper presents the tests and some results of the qualification process relevant to the industrialized tooling provided by the contractor. Results of pre-series junctions done in the LHC tunnel are presented together with the perspective for the continuation of the work.2006-05-19http://cds.cern.ch/record/970376http://cds.cern.ch/record/970376oai:cds.cern.ch:970376 engLa China, MWildner, EScandale, WalterA Simplified Structural Model for the Analysis of Shape Deformations of the LHC Superconducting Dipole Cold MassAccelerators and Storage RingsLHC-PROJECT-Report-882CERN-LHC-Project-Report-882In superconducting magnets for particle accelerators the mechanical accuracy along the length of the Cold Mass is one of the crucial parameters to guarantee the field quality needed by beam dynamics. This issue is made even more challenging in the twin-aperture LHC superconducting dipole where tolerances in the 0.3-1 mm range shall be obtained over a length of 15 m, for a Cold Mass of about 30 tonnes which, to minimize thermal losses, is supported in three points only. To reach this goal a number of geometrical checks and analyses are carried out at all stages of magnet assembly, handling, installation and operation. In this paper we present the structural model of the dipole based on which the checks and the analysis are performed, the nature of the geometrical imperfections identified and the temporary or permanent shape modifications predicted.2006-05-19http://cds.cern.ch/record/970375http://cds.cern.ch/record/970375oai:cds.cern.ch:970375 doi:10.1109/TASC.2006.870496engModena, MBajko, MCornelis, MFessia, PLiénard, PMiles, Jde Rijk, GSavary, FSgobba, StefanoTommasini, DVlogaert, JVöllinger, CWildner, ELHC Superconducting Dipole Production Follow-up: Results of Audit on QA Aspects in IndustryAccelerators and Storage RingsLHC-PROJECT-Report-881CERN-LHC-Project-Report-881The manufacturing of the 1232 Superconducting Main Dipoles for LHC is under way at three European Contractors: Alstom-Jeumont (Consortium), Ansaldo Superconduttori Genova and Babcock Noell Nuclear. The manufacturing is proceeding in a very satisfactory way and in March 2005 the mid production was achieved. To intercept eventually â€ﾜweak points” of the production process still present and in order to make a check of the Quality Assurance and Control in place for the series production, an Audit action was launched by CERN during summer-fall 2004. Aspects like: completion of Production and Quality Assurance documentation, structure of QC Teams, traceability, calibration and maintenance for tooling, incoming components inspections, were checked during a total of seven visits at the five different production sites. The results of the Audit in terms of analysis of â€ﾜsystematic” and â€ﾜrandom” problems encountered as well as corrective actions requested are presented.2006-05-19http://cds.cern.ch/record/97037410.1109/TASC.2006.870496http://cds.cern.ch/record/970374oai:cds.cern.ch:970374 doi:10.1109/TASC.2006.870501engde Rijk, GBajko, MCornelis, MFessia, PMiles, JModena, MMolinari, GRinn, JSavary, FVlogaert, JElectrical Integrity Tests during Production of the LHC DipolesAccelerators and Storage RingsLHC-PROJECT-Report-880CERN-LHC-Project-Report-880For the LHC dipoles, mandatory electrical integrity tests are performed to qualify the cold mass (CM) at four production stages: individual pole, collared coil, CM before end cover welding and final CM. A description of the measurement equipment and its recent development are presented. After passing the demands set out in the specification, the results of the tests are transmitted to CERN where they are further analyzed. The paper presents the most important results of these measurements. We also report a review of the electrical non-conformities encountered e.g. interturn shorts and quench heater failure, their diagnostic and the cures.2006-05-19http://cds.cern.ch/record/97036310.1109/TASC.2006.870501http://cds.cern.ch/record/970363oai:cds.cern.ch:970363 engDenz, RElectronic Systems for the Protection of Superconducting Elements in the LHCAccelerators and Storage RingsLHC-PROJECT-Report-879CERN-LHC-Project-Report-879The Large Hadron Collider LHC, currently under construction at CERN, will incorporate an unprecedented number of superconducting magnets, busbars and current leads. As most of these elements depend on active protection in case of a transition from the superconducting to the resistive state, the so-called quench, a protection system based on modern, state of the art electronics has been developed.2006-05-19http://cds.cern.ch/record/970362http://cds.cern.ch/record/970362oai:cds.cern.ch:970362 doi:10.1109/TASC.2005.869553engRamberger, SBidon, SCornuet, DGérard, DGurov, DHans, OKalbreier, WilliKiselev, OMorozov, IOgurtsov, APetrov, Vde Rijk, GRuvinsky, ESukhanov, AZhilayev, KNormal-Conducting Separation and Compensation Dipoles for the LHC Experimental InsertionsAccelerators and Storage RingsLHC-PROJECT-Report-878CERN-LHC-Project-Report-878The experimental insertions of the LHC make use of normal-conducting magnets to provide for part of the beam separation and to compensate the effect of two large spectrometer dipoles. Three different types with respect to the length were designed and are based on the same type of lamination. The main type of magnet MBXW has a core length of 3.4 m while the MBXWT and MBXWS magnets are 1.5 m and 0.75 m long versions respectively. The magnet design was done in collaboration between CERN and BINP and the dipole magnets are produced by BINP. So far all three MBXWS magnets, all three MBXWT magnets and fifteen of twenty-nine MBXW magnets have been manufactured and delivered to CERN. The report presents the main design issues and results of the acceptance tests including mechanical, electrical and magnetic field measurements.2006-05-19http://cds.cern.ch/record/97036110.1109/TASC.2005.869553http://cds.cern.ch/record/970361oai:cds.cern.ch:970361 engTodesco, EBellesia, BHagen, PVöllinger, CTrends in Field Quality along the Production of the LHC Dipoles and Differences among ManufacturersAccelerators and Storage RingsLHC-PROJECT-Report-877CERN-LHC-Project-Report-877More than two thirds of the dipoles of the Large Hadron Collider have been manufactured and their magnetic field has been measured at room temperature. In this paper we make a review of the trends that have been observed during the production. In some cases, the trends were traced back to displacements of conductors with respect to the nominal lay-out. The analysis allows detecting the most critical zones in the superconducting coil as far as field quality is concerned. The second part of the paper makes the point of the observed differences in field quality between the three manufacturers. The analysis allows evaluating which multipoles are more affected, what magnitudes of displacements are necessary to explain these differences (the manufacturers all producing the same baseline), and what could be the origin of such differences.2006-05-19http://cds.cern.ch/record/970360http://cds.cern.ch/record/970360oai:cds.cern.ch:970360 engPojer, MDevred, ArnaudScandale, WalterA Non-Linear Finite Element Model for the LHC Main Dipole Coil Cross-SectionAccelerators and Storage RingsLHC-PROJECT-Report-876CERN-LHC-Project-Report-876The production of the dipole magnets for the Large Hadron Collider is at its final stage. Nevertheless, some mechanical instabilities are still observed for which no clear explanation has been found yet. A FE modelization of the dipole cold mass cross-section had already been developed at CERN, mainly for magnetic analysis, taking into account conductor blocks and a frictionless behavior. This paper describes a new ANSYS® model of the dipole coil cross-section, featuring individual turns inside conductor blocks, and implementing friction and the mechanical non-linear behavior of insulated cables. Preliminary results, comparison with measurements performed in industry and ongoing developments are discussed.2006-05-19http://cds.cern.ch/record/970359http://cds.cern.ch/record/970359oai:cds.cern.ch:970359 doi:10.1109/TASC.2006.870492engCano, E D FernandezBuzio, MGarcía-Pérez, JJeanneret, Jean BernardPoncet, ASeyvet, FTovar-Gonzalez, AWildner, EStability of the Horizontal Curvature of the LHC Cryodipoles During Cold TestsAccelerators and Storage RingsLHC-PROJECT-Report-875CERN-LHC-Project-Report-875The LHC will be composed of 1232 horizontally curved, 15 meter long, superconducting dipole magnets cooled at 1.9 K. They are supported within their vacuum vessel by three Glass Fiber Reinforced Epoxy (GFRE) support posts. Each cryodipole is individually cold tested at CERN before its installation and interconnection in the LHC 27 km circumference tunnel. As the magnet geometry under cryogenic operation is extremely important for the LHC machine aperture, a new method has been developed at CERN in order to monitor the magnet curvature change between warm and cold states. It enabled us to conclude that there is no permanent horizontal curvature change of the LHC dipole magnet between warm and cold states, although a systematic horizontal transient deformation during cool-down was detected. This deformation generates loads in the dipole supporting system; further investigation permitted us to infer this behavior to the asymmetric thermal contraction of the rigid magnet thermal shield during cool-down. Controlling the helium flow rate in the thermal shield of the cryomagnet enabled us to reduce the maximal deformation by a factor of approximately two, thus increasing significantly the mechanical safety margin of the supporting system during the CERN cold tests.2006-05-19http://cds.cern.ch/record/97035810.1109/TASC.2006.870492http://cds.cern.ch/record/970358oai:cds.cern.ch:970358 doi:10.1109/TASC.2006.871218engSmirnov, NBottura, LCalvi, MDeferne, GDi Marco, JSammut, NSanfilippo, SFocusing Strength Measurements of the Main Quadrupoles for the LHCAccelerators and Storage RingsLHC-PROJECT-Report-874CERN-LHC-Project-Report-874More than 1100 quadrupole magnets of different types are needed for the Large Hadron Collider (LHC) which is in the construction stage at CERN. The most challenging parameter to measure on these quadrupoles is the integrated gradient (Gdl). An absolute accuracy of 0.1% is needed to control the beta beating. In this paper we briefly describe the whole set of equipment used for Gdl measurements: Automated Scanner system, Single Stretched Wire system and Twin Coils system, concentrating mostly on their absolute accuracies. Most of the possible inherent effects that can introduce systematic errors are discussed along with their preventive methods. In the frame of this qualification some of the magnets were tested with two systems. The results of the intersystem cross-calibrations are presented. In addition, the qualification of the measurement system used at the magnet manufacturer's is based on results of more than 40 quadrupole assemblies tested in cold conditions at CERN and in warm conditions at the vendor site.2006-05-19http://cds.cern.ch/record/97035610.1109/TASC.2006.871218http://cds.cern.ch/record/970356oai:cds.cern.ch:970356 doi:10.1109/TASC.2006.871221engGarcía-Pérez, JBillan, JBuzio, MGalbraith, PGiloteaux, DRemondino, VittorioPerformance of the Room Temperature Systems for Magnetic Field Measurements of the LHC Superconducting MagnetsAccelerators and Storage RingsLHC-PROJECT-Report-873CERN-LHC-Project-Report-873The LHC will be composed of 1232 horizontally curved, 15-meter long, superconducting dipole assemblies and 474 Short Straight Sections containing various types of quadrupoles. These magnets are manufactured by several European companies and half of them are currently produced. The field quality at room temperature is strictly monitored to guide and validate the assembly at different stages of the production in the industry. Dipoles and quadrupoles are measured with two different rotating coil systems. These â€ﾜmoles” travel inside the 50 mm aperture and accurately measure the field and gradient strength integrated over the length, the field direction and high order harmonics. We describe here these two systems, their performance and the experience gained through the two first years of operation.2006-05-19http://cds.cern.ch/record/97035410.1109/TASC.2006.871221http://cds.cern.ch/record/970354oai:cds.cern.ch:970354 doi:10.1109/TASC.2005.864262engCalvi, MTodesco, EBottura, LSanfilippo, SSiemko, AImpact of the First Powering Cycles on the LHC Superconducting Dipole Coil GeometryAccelerators and Storage RingsLHC-PROJECT-Report-872CERN-LHC-Project-Report-872The impact of the first powering cycles on the LHC superconducting dipoles coil geometry has been investigated. Dedicated magnetic measurements have been performed to estimate the changes in the geometric component of the harmonics, caused by the last highest Lorentz force the coil has ever experienced. Several magnets have been powered at increasing current steps while the field quality has been measured to quantify the changes in geometry. The effect of the thermal cycles has been also considered as well as the systematic differences between measurements before and after the quench training. The reconstruction of the coil geometry variations is discussed in terms of continuous modes of deformation as well as single block displacements.2006-05-19http://cds.cern.ch/record/97034910.1109/TASC.2005.864262http://cds.cern.ch/record/970349oai:cds.cern.ch:970349 doi:10.1109/TASC.2006.870504engBellesia, BMolinari, GSantoni, CScandale, WalterTodesco, EShort Circuit Localization in the LHC Main Dipole Coils by means of Room Temperature Magnetic MeasurementsAccelerators and Storage RingsLHC-PROJECT-Report-871CERN-LHC-Project-Report-871During the construction of the LHC main dipoles, 12 cases of short circuits between the cables of the superconducting coils have been detected. Some of them appeared only under the press, making impossible their localization after disassembly. In this paper we describe a method to locate electrical shorts through the use of room temperature magnetic measurements. An example case is discussed in detail to illustrate the features of the approach, and a statistic of the cases met during the production of more that 70% of the dipole total quantity is presented.2006-05-19http://cds.cern.ch/record/97034710.1109/TASC.2006.870504http://cds.cern.ch/record/970347oai:cds.cern.ch:970347 engBuzio, MBeauquis, JBottura, LCoccoli, MDeferne, GKrotov, NLaface, ERuccio, AGarcía-Pérez, JMissiaen, DSchnizer, PSmirnov, NWildner, EWinkes, PWarm and Cold Magnetic and Mechanical Alignment Tests of LHC Short Straight SectionsAccelerators and Storage RingsLHC-PROJECT-Report-870CERN-LHC-Project-Report-870This paper contains a summary of the results of the magnetic and mechanical alignment tests performed at CERN on the first 111 arc Short Straight Sections. These include the mechanical axis of the Cold Bore Tube at room temperature, the magnetic axis of main quadrupoles and correctors at both room and cryogenic temperature, and the field direction of the main quadrupoles. The measurements show that the quality of the assemblies is generally within the requirements for the machine.2006-05-19http://cds.cern.ch/record/970342http://cds.cern.ch/record/970342oai:cds.cern.ch:970342 engBuzio, MBottura, LBrun, GFievez, GGalbraith, PGarcía-Pérez, JLópez, RMasi, ARussenschuck, StephanSmirnov, NTikhov, AChecking the Polarity of Superconducting Multipole LHC MagnetsAccelerators and Storage RingsLHC-PROJECT-Report-869CERN-LHC-Project-Report-869This paper describes the design and operation of the â€ﾜPolarity Checker”, a scanning probe designed to check multipole field order, type and polarity of superconducting LHC magnets. First we introduce the measurement method, based on the harmonic analysis of the radial field component picked up by a rotating Hall sensor at different current levels. Then we describe the hardware and the software of the system, which features automatic powering, data acquisition and treatment, discussing the achieved sensitivity and performance. Finally we provide a summary of the test results on the first 505 cryoassemblies, showing how the system was usefully employed to detect some potentially harmful connection errors.2006-05-19http://cds.cern.ch/record/970340http://cds.cern.ch/record/970340oai:cds.cern.ch:970340 engSchirm, K MKalbreier, WilliAnashin, VKiselev, OMaraev, VOgurtsov, APupkov, YuRuvinsky, EZhilyaev, KKonstantinov, Yu SKosjakin, MPeregud, VThe Bending Magnets for the Proton Transfer Line of CNGSAccelerators and Storage RingsCERN-AT-2006-003-MELThe project "CERN neutrinos to Gran Sasso (CNGS)", a collaboration between CERN and the INFN (Gran Sasso Laboratory) in Italy, will study neutrino oscillations in a long base-line experiment. High-energy protons will be extracted from the CERN SPS accelerator, transported through a 727 m long transfer line and focused onto a graphite target to produce a beam of pions and kaons and subsequently neutrinos. The transfer line requires a total of 78 dipole magnets. They were produced in the framework of an in-kind contribution of Germany via DESY to the CNGS project. The normal conducting dipoles, built from laminated steel cores and copper coils, have a core length of 6.3 m, a 37 mm gap height and a nominal field range of 1.38 T - 1.91 T at a maximum current of 4950 A. The magnet design was a collaboration between CERN and BINP. The half-core production was subcontracted to EFREMOV Institute; the coil fabrication, magnet assembly and the field measurements were concluded at BINP in June 2004. The main design issues and results of the acceptance tests, including mechanical, electrical and magnetic field measurements, are discussed.2006-05-26http://cds.cern.ch/record/967485http://cds.cern.ch/record/967485oai:cds.cern.ch:967485Work supported in part by the European Community-Research infrastructure activity under the FP6 Program engCalvi, MBottura, LBreschi, MCoccoli, MGranieri, PIriart, GLecci, FSiemko, AAnalytical Model of Thermo-electrical Behaviour in Superconducting Resistive Core CablesAccelerators and Storage RingsCERN-AT-2006-004-MTMHigh field superconducting Nb$_{3}$Sn accelerators magnets above 14 T, for future High Energy Physics applications, call for improvements in the design of the protection system against resistive transitions. The longitudinal quench propagation velocity (vq) is one of the parameters defining the requirements of the protection. Up to now vq has been always considered as a physical parameter defined by the operating conditions (the bath temperature, cooling conditions, the magnetic field and the over all current density) and the type of superconductor and stabilizer used. It is possible to enhance the quench propagation velocity by segregating a percent of the stabilizer into the core, although keeping the total amount constant and tuning the contact resistance between the superconducting strands and the core. Analytical model and computer simulations are presented to explain the phenomenon. The consequences with respect to minimum quench energy are evidenced and the strategy to optimize the cable designed is discussed.2006-06-12http://cds.cern.ch/record/967166http://cds.cern.ch/record/967166oai:cds.cern.ch:967166revised version submitted on 2006-06-28 17:26:18Work supported in part by the European Community-Research infrastructure activity under the FP6 Program