Paper |
Title |
Page |
MOPRO031 |
Abort Gap Cleaning for LHC Run 2 |
138 |
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- J.A. Uythoven, A. Boccardi, E. Bravin, B. Goddard, G.H. Hemelsoet, W. Höfle, D. Jacquet, V. Kain, S. Mazzoni, M. Meddahi, D. Valuch
CERN, Geneva, Switzerland
- E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
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To minimize the beam losses at the moment of an LHC beam dump the 3 μs long abort gap should contain as few particles as possible. Its population can be minimised by abort gap cleaning using the LHC transverse damper system. The LHC Run 1 experience is briefly recalled; changes foreseen for the LHC Run 2 are presented. They include improvements in the observation of the abort gap population and the mechanism to decide if cleaning is required, changes to the hardware of the transverse dampers to reduce the detrimental effect on the luminosity lifetime and proposed changes to the applied cleaning algorithms.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO031
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MOPRI096 |
The New Transfer Line Collimation System for the LHC High Luminosity Era |
839 |
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- V. Kain, C. Bracco, B. Goddard, F.L. Maciariello, M. Meddahi, A. Mereghetti, G.E. Steele, F.M. Velotti
CERN, Geneva, Switzerland
- E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
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A set of passive absorbers is located at the end of each of the 3 km long injection lines to protect the LHC in case of failures during the extraction process from the LHC’s last pre-injector or the beam transfer itself. In case of an erroneous extraction, the absorbers have to attenuate the beam to a safe level and be robust enough themselves to survive the impact. These requirements are difficult to fulfil with the very bright and intense beams produced by the LHC injectors for the high luminosity era. This paper revisits the requirements for the SPS-to-LHC transfer line collimation system and the adapted strategy to fulfill these for the LHC high luminosity operation. A possible solution for the new transfer line collimation system is presented.
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DOI • |
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※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI096
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MOPRI100 |
Investigations of SPS Orbit Drifts |
852 |
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- L.N. Drøsdal, C. Bracco, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, J. Wenninger
CERN, Geneva, Switzerland
- E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
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The LHC is filled from the last pre-injector, the Super Proton Synchrotron (SPS), via two 3 km long transfer lines, TI 2 and TI 8. Over the LHC injection processes, a drift of the beam trajectories has been observed in TI 2 and TI 8, requiring regular correction of the trajectories, in order to ensure clean injection into the LHC. Investigations of the trajectory variations in the transfer lines showed that the main source of short term trajectory drifts are current variations of the SPS extraction septa (MSE). The stability of the power converters has been improved, but the variations are still present and further improvements are being investigated. The stability over a longer period of time cannot be explained by this source alone. The analysis of trajectory variations shows that there are also slow variations in the SPS closed orbit at extraction. A set of SPS orbit measurements has been saved and analysed. These observations will be used together with simulations and observed field errors to locate the second source of variations.
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DOI • |
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※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI100
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WEPRO068 |
SPS Beam Steering for LHC Extraction |
2106 |
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- E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
- H. Bartosik, K. Cornelis, L.N. Drøsdal, B. Goddard, V. Kain, M. Meddahi, Y. Papaphilippou, J. Wenninger
CERN, Geneva, Switzerland
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The CERN Super Proton Synchrotron accelerates beams for the Large Hadron Collider to 450 GeV. In addition it produces beams for fixed target facilities which adds complexity to the SPS operation. During the run 2012-2013 drifts of the extracted beam trajectories have been observed and lengthy optimizations in the transfer lines were performed to reduce particle losses in the LHC. The observed trajectory drifts are consistent with the measured SPS orbit drifts at extraction. While extensive studies are going on to understand, and possibly suppress, the source of such SPS orbit drifts the feasibility of an automatic beam steering towards a “golden” orbit at the extraction septa, by means of the interlocked correctors, is also being investigated. The challenges and constraints related to the implementation of such a correction in the SPS are described. Simulation results are presented and a possible operational steering strategy is proposed.
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※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO068
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