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Abstract-The production of superconducting magnets for particle accelerators involves high precision assemblies and tight tolerances, in order to achieve the requirements for their appropriate performance. It is therefore essential to have a strict control and traceability over the geometry of each component of the system, and also to be able to compensate possible inherent deviations coming from the production process.The objective of this paper is to present the experience from systematic geometrical measurements performed during the on-going production of model magnets for the High Luminosity -LHC upgrade. First, the methodology for the data acquisition and its ulterior analysis is described. Then, the results obtained in terms of coil geometry are explained with the goal of identifying the principal factors causing systematic and unexpected dimensional deviations. Finally, the integrated effect of assembly operations, cool down and powering of the magnet is investigated looking at measurements before and after cold tests.  Index Terms-Geometrical measurements, metrology, superconducting model magnets for particle accelerators, MQXFS, 11 T dipole, HL-LHC models.

The normal and superconducting magnets for the LHC ring have been carefully examined to insure that each of about 1900 assemblies is suitable for the operation in the accelerator. Hardware experts and accelerator physicists have contributed to this work that consisted in magnet acceptance, and sorting according to geometry, field quality and quench level. This paper gives a description of the magnet approval mechanism that has been running since four years, reporting in a concise summary the main results achieved. AbstractThe normal and superconducting magnets for the LHC ring have been carefully examined to insure that each of about 1900 assemblies is suitable for the operation in the accelerator. Hardware experts and accelerator physicists have contributed to this work that consisted in magnet acceptance, and sorting according to geometry, field quality and quench level. This paper gives a description of the magnet approval mechanism that has been running since four years, reporting in a concise summary the main results achieved.

The Large Hadron Collider Short Straight Sections (SSS) are currently being installed in their final position in the accelerator tunnel. For all the SSSs, both those in the regular arcs as well as those in the insertion regions, magnetic axis and geometric measurements are made at different steps of their assembly. These stages range from production in the industry to the cryostating at CERN, as well as during and after cold tests or during installation of the BPM/beam screen assembly. The results of the geometry at the various production stages by means of different procedures and analysis tools are reported and discussed in details in this paper.

The 15 m long main dipoles for the Large Hadron Collider have now been installed in their final positions in the accelerator tunnel. Geometric measurements of the magnets after many of the production steps from industry to the cryostating, after cold tests and after preparation of the magnets for installation, have been made, permitting careful control of the shape of the magnet, the positioning of the field correctors, and the final positioning in the tunnel.The result of the geometry control at the different production stages, from industry to CERN, using different kinds of control procedures and analysis, is reported. AbstractThe 15 m long main dipoles for the Large Hadron Collider have now been installed in their final positions in the accelerator tunnel. Geometric measurements of the magnets after many of the production steps from industry to the cryostating, after cold tests and after preparation of the magnets for installation, have been made, permitting careful control of the shape of the magnet, the positioning of the field correctors, and the final positioning in the tunnel. The result of the geometry control at the different production stages, from industry to CERN, using different kinds of control procedures and analysis, is reported.