Paper |
Title |
Page |
MOP245 |
Quench Tests at the Large Hadron Collider with Collimation Losses at 3.5 Z TeV |
157 |
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- S. Redaelli, R.W. Aßmann, G. Bellodi, K. Brodzinski, R. Bruce, F. Burkart, M. Cauchi, D. Deboy, B. Dehning, E.B. Holzer, J.M. Jowett, E. Nebot Del Busto, M. Pojer, A. Priebe, A. Rossi, M. Sapinski, M. Schaumann, R. Schmidt, M. Solfaroli Camillocci, G. Valentino, R. Versteegen, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
- L. Lari
IFIC, Valencia, Spain
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The Large Hadron Collider (LHC) has been operating since 2010 at 3.5 TeV and 4.0 TeV without experiencing quenches induced by losses from circulating beams. This situation might change at 7 TeV where the reduced margins in the superconducting magnets. The critical locations are the dispersion suppressors (DSs) at either side of the cleaning and experimental insertions, where dispersive losses are maximum. It is therefore crucial to understand in detail the quench limits with beam loss distributions alike those occurring in standard operation. In order to address this aspect, quench tests were performed by inducing large beam losses on the primary collimators of the betatron cleaning insertion, for proton and lead ion beams of 3.5 Z TeV, to probe the quench limits of the DS magnets. Losses up to 500 kW were achieved without quenches. The measurement technique and the results obtained are presented, including observations of heat loads in the cryogenics system.
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MOP248 |
Brightness Evolution for LHC Beams during the 2012 Run |
170 |
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- M. Kuhn
Uni HH, Hamburg, Germany
- G. Arduini, J.F. Comblin, A. Guerrero, V. Kain, B. Mikulec, F. Roncarolo, M. Sapinski, M. Schaumann, R. Steerenberg
CERN, Geneva, Switzerland
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One of the reasons for the remarkable achievements of the LHC is the excellent performance of the LHC injector chain. The evolution of the brightness in the injectors and at LHC collision in 2011 and 2012 is discussed. During certain run periods, the brightness from the beam provided by the injectors was lower than usual. Some of the issues have been identified so far and will be reported. The latest results on emittance blow-up investigations through the 2012 LHC cycle will also be presented and compared to the 2011 data. Possible implications for LHC upgrade scenarios will be mentioned.
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WEO1A02 |
LHC Impedance Model: Experience with High Intensity Operation in the LHC |
349 |
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- B. Salvant, O. Aberle, G. Arduini, R.W. Aßmann, V. Baglin, M.J. Barnes, P. Baudrenghien, A. Bertarelli, C. Bracco, R. Bruce, X. Buffat, F. Carra, F. Caspers, G. Cattenoz, S.D. Claudet, H.A. Day, J.F. Esteban Müller, M. Garlaschè, L. Gentini, B. Goddard, A. Grudiev, B. Henrist, W. Herr, S. Jakobsen, R.J. Jones, G. Lanza, L. Lari, T. Mastoridis, N. Mounet, E. Métral, A.A. Nosych, J.L. Nougaret, S. Persichelli, T. Pieloni, A.M. Piguiet, S. Redaelli, F. Roncarolo, G. Rumolo, B. Salvachua, M. Sapinski, E.N. Shaposhnikova, L.J. Tavian, M.A. Timmins, J.A. Uythoven, A. Vidal, R. Wasef, D. Wollmann
CERN, Geneva, Switzerland
- A.V. Burov
Fermilab, Batavia, USA
- S.M. White
BNL, Upton, Long Island, New York, USA
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The CERN Large Hadron Collider (LHC) is now in luminosity production mode and has been pushing its performance in the past months by increasing the proton beam brightness, the collision energy and the machine availability. As a consequence, collective effects have started to become more and more visible and have effectively slowed down the performance increase of the machine. Among these collective effects, the interaction of brighter LHC bunches with the longitudinal and transverse impedance of the machine has been observed to generate beam induced heating and transverse instabilities since 2010. This contribution reviews the current LHC impedance model obtained from theory, simulations and bench measurements as well as a selection of measured effects with the LHC beam.
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Slides WEO1A02 [7.991 MB]
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