| Paper |
Title |
Page |
| TUPAN088 |
Beam Scraping for LHC Injection
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1580 |
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- H. Burkhardt, G. Arduini, S. Bart Pedersen, C. Fischer, JJ. G. Gras, A. Koschik, D. K. Kramer, S. Redaelli
CERN, Geneva
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Operation of the LHC will require injection of very high intensity beams from the SPS to the LHC. Fast scrapers have been installed and will be used in the SPS to detect and remove any existing halo before beams are extracted, to minimize the probability for quenching of super-conducting magnets at injection in the LHC. We briefly review the functionality of the scraper system and report about measurements that have recently been performed in the SPS on halo scraping and re-population of tails.
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| TUPAN097 |
Studies of Beam Losses from Failures of SPS Beam Dump Kickers
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1607 |
| |
- T. Kramer, G. Arduini, O. E. Berrig, E. Carlier, L. Ducimetiere, B. Goddard, A. Koschik, J. A. Uythoven
CERN, Geneva
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The SPS beam dump extraction process was studied in detail to investigate the possibility of operation with reduced kicker voltage and to fully understand the trajectory and loss pattern of the mis-kicked beams. This paper briefly describes the SPS beam dump process, and presents the tracking studies carried out for failure cases. The simulation results are compared to the results of measurements made with low intensity beams.
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| TUPAN107 |
Beam Loss Response Measurements with an LHC Prototype Collimator in the SPS
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1622 |
| |
- Th. Weiler, G. Arduini, R. W. Assmann, C. Bracco, H.-H. Braun, B. Dehning, P. Gander, E. B. Holzer, M. Jonker, R. Losito, A. Masi, L. Ponce, S. Redaelli, G. Robert-Demolaize, M. Sobczak, J. Wenninger
CERN, Geneva
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Beam tests with an LHC prototype collimator were performed at the SPS in autumn 2006. Applying a new collimator control system many new beam measurements were performed. This contribution presents results on collimator-induced beam loss measurements and their applications to beam-based alignment of collimators and measurements of the beam size and position. Interesting features of the recorded beam loss signals are illustrated and possible impacts for LHC operation are discussed. The measured loss distributions around the full SPS ring are analyzed and compared with simulations.
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| WEOAC03 |
Transverse Impedance of LHC Collimators
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2003 |
| |
- E. Metral, G. Arduini, R. W. Assmann, A. Boccardi, T. Bohl, C. Bracco, F. Caspers, M. Gasior, O. R. Jones, K. K. Kasinski, T. Kroyer, S. Redaelli, G. Robert-Demolaize, G. Rumolo, R. J. Steinhagen, Th. Weiler, F. Zimmermann
CERN, Geneva
- F. Roncarolo
UMAN, Manchester
- B. Salvant
EPFL, Lausanne
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The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams in case of failures, and which will be moved very close to the beam, with full gaps of few millimetres, in order to protect surrounding super-conducting equipments. We present an estimate of the transverse resistive-wall impedance of the LHC collimators, the total impedance in the LHC at injection and top energy, the induced coupled-bunch growth rates and tune shifts, and finally the result of the comparison of the theoretical predictions with measurements performed in 2004 and 2006 on a prototype collimator installed in the SPS.
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Slides
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| FRPMN065 |
Fast Vertical Single-Bunch Instability at Injection in the CERN SPS - An Update
|
4162 |
| |
- G. Arduini, T. Bohl, H. Burkhardt, E. Metral, G. Rumolo
CERN, Geneva
- B. Salvant
EPFL, Lausanne
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Following the first observation of a fast vertical instability for a single high-brightness bunch at injection in the SPS in 2003, a series of detailed measurements and simulations has been performed in order to assess the resulting potential intensity limitations for the SPS, as well as possible cures. During the 2006 run, the characteristics of this instability were studied further, extending the intensity range of the measurements, and comparing the experimental data with simulations that take into account the latest measurements of the transverse machine impedance. In this paper, we summarize the outcome of these studies and our understanding of the mechanisms leading to this instability. The corresponding intensity limitations were also determined.
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| FRPMN076 |
Nominal LHC Beam Instability Observations in the CERN Proton Synchrotron
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4222 |
| |
- R. R. Steerenberg, G. Arduini, E. Benedetto, A. Blas, W. Hofle, E. Metral, M. Morvillo, C. Rossi, G. Rumolo
CERN, Geneva
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The nominal LHC beam has been produced successfully in the CERN Proton Synchrotron since 2003. However, after having restarted the CERN PS in spring 2006, the LHC beam was set-up and observed to be unstable on the 26 GeV/c extraction flat top. An intensive measurement campaign was made to understand the instability and to trace its source. This paper presents the observations, possible explanations and the necessary measures to be taken in order to avoid this instability in the future.
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| FRPMN078 |
Improved Algorithms to Determine Non-Linear Optics Model of the SPS from Non-Linear Chromaticity
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4231 |
| |
- R. Tomas, G. Arduini, G. Rumolo, F. Zimmermann
CERN, Geneva
- R. Calaga
BNL, Upton, Long Island, New York
- A. Faus-Golfe
IFIC, Valencia
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Funding: This work is partially supported by the U. S. DOE
In recent years several measurements of the SPS non-linear chromaticity have been performed in order to determine the non-linear optics model of the SPS machine at injection energy for different cycles. In 2006 additional measurements have been performed at injection and during the ramp for the cycle used to accelerate the LHC beam. New and more robust matching algorithms have been developed in 2006 to fit the model to the measurements up to arbitrary chromatic order. In this paper we describe the algorithms used in the analysis of the data and we summarize and compare the results from all experiments.
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