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Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395)
The aim of this analysis is to study if the field quality in a large aperture low-beta superconducting quadrupole for the LHC upgrade limits the beam performances due to increased geometric aberrations. Random field errors in superconducting quadrupoles are usually estimated by computing the effect of a random positioning of the coil blocks around the nominal position with an r.m.s. of 0.05 mm. Here, we review the experience acquired in the construction of 7 superconducting quadrupoles in the RHIC and in the LHC projects to estimate the precision in the block positioning, showing that there is no visible dependence on the magnet aperture. Different magnet models are then used to estimate the expected field quality in quadrupoles with apertures ranging from 50 to 200 mm. The impact on geometrical aberrations and scaling laws for their dependence on the aperture are finally evaluated.
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- R. I. Saban, R. Alemany-Fernandez, V. Baggiolini, A. Ballarino, E. Barbero-Soto, B. Bellesia, F. Bordry, D. Bozzini, M. P. Casas Lino, V. Chareyre, S. D. Claudet, G.-J. Coelingh, K. Dahlerup-Petersen, R. Denz, M. Gruwe, V. Kain, G. Kirby, M. Koratzinos, R. J. Lauckner, S. L.N. Le Naour, K. H. Mess, F. Millet, V. Montabonnet, D. Nisbet, B. Perea-Solano, M. Pojer, R. Principe, S. Redaelli, A. Rijllart, F. Rodriguez-Mateos, R. Schmidt, L. Serio, A. P. Siemko, M. Solfaroli Camillocci, H. Thiesen, W. Venturini Delsolaro, A. Vergara-Fernandez, A. P. Verweij, M. Zerlauth
CERN, Geneva
- SF. Feher, R. H. Flora, R. Rabehl
Fermilab, Batavia, Illinois
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The LHC is an accelerator with unprecedented complexity; in addition, the energy stored in magnets and the beams exceeds other accelerators by one to two orders of magnitude. To avoid a plague of technical problems and ensure a safe machine start-up, the hardware commissioning phase was emphasized: the thorough commissioning of technical systems (vacuum, cryogenics, quench protection, power converters, electrical circuits, AC distribution, ventilation, demineralised water, injection system, beam dumping system, beam instrumentation, etc) is carried-out without beam. Activity started in June 2005 with the commissioning of individual systems, followed by operating a full sector of the machine as a whole. LHC architecture allows the commissioning of each of the eight sectors independently from the others, before the installation of other sectors is complete. Important effort went into the definition of the programme and the organization of the coordination in the field, as well as in the tools to record and analyze test results. This paper presents the experience with this approach, results from the commissioning of the first LHC sectors and gives an outlook for future activities.
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