Paper |
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WEPME018 |
CERN Vacuum System Activities during the Long Shutdown 1: The LHC’s injector chain. |
2291 |
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- J.A. Ferreira Somoza, P. Chiggiato
CERN, Geneva, Switzerland
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During the long shutdown 1 (LS1), several maintenance, consolidation and upgrade activities have been carried out in LHC’s injector chain. Each machine has specific vacuum requirements and different history, which determine the present status of the vacuum components, their maintenance and consolidation needs. The present work presents the priorities agreed at the beginning of the LS1 period and their implementation. Of particular relevance are the interventions in radioactive controlled areas where several leaks due to stress corrosions stopped the operations in the past years. The strategy to reduce the collective dose is presented, in particular the use of remote controlled robots. An important part of the work performed during this period involves supporting other teams (acceptance tests, new equipment installation, etc.). Finally, as a result of the LS1 experience, a medium to long term strategy is depicted, focusing on the preparation of the next shutdown (LS2) and the integration of LINAC4 in the injector chain during the same period.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME018
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WEPME040 |
Development of Aluminium Vacuum Chambers for the LHC Experiments at CERN |
2354 |
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- M.A. Gallilee, P. Chiggiato, P. Costa Pinto, L.M.A. Ferreira, P. Lepeule, J. Perez Espinos, L. Prever-Loiri, A. Sapountzis
CERN, Geneva, Switzerland
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Beam losses may cause activation of vacuum chamber walls, in particular those of the Large Hadron Collider (LHC) experiments. For the High Luminosity LHC, the activation of such vacuum chambers will increase. It is therefore necessary to use a vacuum chamber material which interacts less with the circulating beam. While beryllium is reserved for the collision point, a good compromise between cost, availability and transparency is obtained with aluminium alloys; such materials are a preferred choice with respect to austenitic stainless steel. Manufacturing a thin-wall aluminium vacuum chamber presents several challenges as the material grade needs to be machinable, weldable, leak-tight for small thicknesses, and able to withstand heating to 250°C for extended periods of time. This paper presents some of the technical challenges during the manufacture of these vacuum chambers and the methods for overcoming production difficulties, including surface treatments and NEG thin-film coating.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME040
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WEPME041 |
Vacuum Acceptance Tests for the UHV Room Temperature Vacuum System of the LHC during LS1 |
2357 |
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- G. Cattenoz, V. Baglin, G. Bregliozzi, D. Calegari, P. Chiggiato, J.E. Gallagher, A. Marraffa
CERN, Geneva, Switzerland
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During the CERN Large Hadron Collider (LHC) first long shut down (LS1), a large number of vacuum tests are carried out on consolidated or newly fabricated pieces of equipment. In such a way, the vacuum compatibility is assessed before installation in the UHV system of the LHC. According to the equipment’s nature, the vacuum acceptance tests consist in functional checks, leak tests, outgassing rate measurements, evaluation of contaminants by Residual Gas Analysis (RGA), pumping speed measurements, and qualification of the sticking probability of Non-Evaporable-Getter coating. In this paper, the methods used for the tests and the acceptance criteria are described. A summary of the measured vacuum characteristics for the tested components is also given.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME041
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WEPME042 |
The LHC Vacuum Pilot Sectors Project |
2360 |
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- B. Henrist, V. Baglin, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland
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The operation of the CERN Large Hadron Collider (LHC) at nominal beam parameters is expected for the next years (2015). Increased synchrotron-radiation stimulated-desorption and electron-cloud build-up are expected. A deep understanding of the interactions between the proton beams and the beampipe wall is mandatory to control the anticipated beam-induced pressure rise. A Vacuum Pilot Sector (VPS) has been designed to monitor the performance of the vacuum system with time. The VPS is installed along a double LHC room temperature vacuum sector (18 m long, 80 mm inner diameter beam pipes) and includes 8 standard modules, 1.4 m long each. Such modules are equipped with residual gas analysers, Bayard-Alpert gauges, photon and electron flux monitors, etc. The chosen modular approach opens the possibility of studying different configurations and implementing future modifications. This contribution will describe the apparatus, the control system designed to drive measurements and possible applications during the next LHC operational phase.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME042
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WEPME043 |
Design and Qualification of Transparent Beam Vacuum Chamber Supports for the LHCb Experiment |
2363 |
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- J.L. Bosch, P. Chiggiato, C. Garion
CERN, Geneva, Switzerland
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Beryllium beam vacuum chambers pass through the aperture of the large dipole magnet and particle acceptance region of the LHCb experiment, coaxial to the LHC beam. At the interior of the magnet, a system of rods and cables supports the chambers, holding them rigidly in place, in opposition to the vacuum forces caused by their conical geometry. In the scope of the current upgrade program, the steel and aluminium structural components are replaced by a newly designed system, making use of Beryllium, in addition to a number of organic materials, and are optimized for overall transparency to incident particles. Presented in this paper are the design criteria, along with the unique design developments carried out at CERN, and furthermore, a description of the technologies procured from industrial partners, specifically in obtaining the best solution for the cable components.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME043
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WEPME044 |
LHC Experimental Beam Pipe Upgrade during LS1 |
2366 |
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- G. Lanza, V. Baglin, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland
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The LHC experimental beam pipes are being improved during the ongoing long shutdown 1 (LS1). Several vacuum chambers have been tested and validated before their installation inside the detectors. The validation tests include: leak tightness, ultimate vacuum pressure, material outgassing rate, and residual gas composition. NEG coatings are assessed by hydrogen sticking probability measurement with the help of Monte Carlo simulations. In this paper the motivation for the beam pipe upgrade, the validation tests of the components and the results are presented and discussed.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME044
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WEPME045 |
Assessment of New Components to be Integrated in the LHC Room Temperature Vacuum System |
2369 |
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- G. Bregliozzi, V. Baglin, P. Chiggiato
CERN, Geneva, Switzerland
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Integration of new equipment in the long straight sections (LSS) of the LHC must be compatible with the TiZrV non-evaporable getter thin film that coats most of the 6-km-long room-temperature beam pipes. This paper focus on two innovative accelerator devices to be installed in the LSS during the long shutdown 1 (LS1): the beam gas vertex (BGV) and a beam bending experiment using crystal collimator (LUA9). The BGV necessitates a dedicated pressure bump, generated by local gas injection, in order to create the required rate of inelastic beam-gas interactions. The LAU9 experiments aims at improving beam cleaning efficiency with the use of a crystal collimator. New materials like fibre optics, piezoelectric components, and glues are proposed in the original design of the two devices. The integration feasibility of these set-ups in the LSS is presented. In particular outgassing tests of special components, X-rays photoelectron spectroscopy, analysis of NEG coating behaviour in presence of glues during bake-out, and pressure profile simulations will be presented.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME045
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WEPME046 |
The HIE-Isolde Vacuum System |
2372 |
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- G. Vandoni, S. Blanchard, P. Chiggiato, K. Radwan
CERN, Geneva, Switzerland
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The High Intensity and Energy Isolde (HIE-Isolde) project aims at increasing the energy and intensity of the radioactive ion beams (RIB) delivered by the present Rex-Isolde facility. Energy up to 10MeV/amu will be reached by a new post-accelerating, superconducting (SC) linac. Beam will be delivered via a HEBT to three experimental stations for nuclear physics. To keep the SC linac compact and avoid cold-warm transitions, the cryomodules feature a common beam and insulation vacuum. Radioactive ion beams require a hermetically sealed vacuum, with transfer of the effluents to the nuclear ventilation chimney. Hermetically sealed, dry, gas transfer vacuum pumps are preferred to gas binding pumps, for an optimized management of radioactive contamination risk during maintenance and intervention. The vacuum system of the SC-linac is isolated by two fast valves, triggered by fast reacting cold cathode gauges installed on the warm linac, the HEBT and the experimental stations. Rough pumping is distributed, while the HEBT turbomolecular pumps also share a common backing line. Slow pumpdown and ventilation of the cryomodules are studied to avoid particulate movement in the viscous regime.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME046
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WEPME047 |
CERN Vacuum System Activities during the Long Shutdown 1: the LHC Beam Vacuum |
2375 |
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- V. Baglin, G. Bregliozzi, P. Chiggiato, J.M. Jimenez, G. Lanza
CERN, Geneva, Switzerland
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After the Long Shutdown 1 (LS1) and the consolidation of the magnet bus bars, the CERN Large Hadron Collider (LHC) will operate with nominal beam parameters. Larger beam energy, beam intensities and luminosity are expected. Despite the very good performance of the beam vacuum system during the 2010-12 physics run (Run 1), some particular areas require attention for repair, consolidation and upgrade. Among the main activities, a large campaign aiming at the repair of the RF bridges of some vacuum modules is conducted. Moreover, consolidation of the cryogenic beam vacuum systems with burst disk for safety reasons is implemented. In addition, NEG cartridges, NEG coated inserts and new instruments for the vacuum system upgrade are installed. Besides these activities, repair, consolidation and upgrades of other beam equipment such as collimators, kickers and beam instrumentations are carried out. In this paper, the motivation and the description for such activities, together with the expected beam vacuum performance after LS1, are described in detail.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME047
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