| Paper |
Title |
Page |
| MOPLS012 |
The LHC Sector Test
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559 |
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- M. Lamont, R. Bailey, H. Burkhardt, B. Goddard, L.K. Jensen, O.R. Jones, V. Kain, A. Koschik, R.I. Saban, J.A. Uythoven, J. Wenninger
CERN, Geneva
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The proposal to inject beam into a sector of the partially completed LHC is presented. The test will provide an important milestone, force preparation of a number of key systems, and allow a number of critical measurements with beam. The motivation for the test is discussed, along with the proposed beam studies, the radiation issues and the potential impact on ongoing installation. The demands on the various accelerator systems implicated are presented along with the scheduling of the preparatory steps, the test itself and the recovery phase.
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| TUPLS014 |
Optics Flexibility and Dispersion Matching at Injection into the LHC
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1517 |
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- A. Koschik, H. Burkhardt, B. Goddard, Y. Kadi, V. Kain, V. Mertens, T. Risselada
CERN, Geneva
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The LHC requires very precise matching of transfer line and LHC optics to minimise emittance blow-up and tail repopulation at injection. The recent addition of a comprehensive transfer line collimation system to improve the protection against beam loss has created additional matching constraints and consumed a significant part of the flexibility contained in the initial optics design of the transfer lines. Optical errors, different injection configurations and possible future optics changes require however to preserve a certain tuning range. Here we present methods of tuning optics parameters at the injection point by using orbit correctors in the main ring, with the emphasis on dispersion matching. The benefit of alternative measures to enhance the flexibility is briefly discussed.
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| WEPCH043 |
On the Implementation of Experimental Solenoids in MAD-X and their Effect on Coupling in the LHC
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2011 |
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- A. Koschik, H. Burkhardt, T. Risselada, F. Schmidt
CERN, Geneva
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The betatron coupling introduced by the experimental solenoids in the LHC is small at injection and negligible at collision energy. We present a study of these effects and look at possible corrections. Additionally we report about the implementation of solenoids in the MAD-X program. A thin solenoid version is also made available for tracking purposes.
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| WEPCH140 |
Recent Improvements of PLACET
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2251 |
| |
- A. Latina, H. Burkhardt, L. Neukermans, G. Rumolo, D. Schulte, R. Tomas
CERN, Geneva
- P. Eliasson
Uppsala University, Uppsala
- J. Resta-López
IFIC, Valencia
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The tracking code PLACET is used to simulate the beam transport in linear colliders from the damping ring to the interaction point and beyond. Recent improvements of the code are presented. They include the possibility to simulate bunch compressors and to use parallel computer systems.
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| THPCH019 |
Halo and Tail Generation Studies for Linear Colliders
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2823 |
| |
- L. Neukermans, H. Burkhardt
CERN, Geneva
- J. Resta-López
IFIC, Valencia
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Halo particles in linear colliders can result in significant losses and serious background which may reduce the overall performances. We present a study of various halo generation processes with numerical estimates. The aim is to allow to predict and minimize the halo throughout the accelerator chain including the final focus up to the experimental detectors. We include estimates for the planned CLIC beam line.
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| THPCH057 |
The Fast Vertical Single-bunch Instability after Injection into the CERN Super Proton Synchrotron
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2913 |
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- E. Métral, G. Arduini, T. Bohl, H. Burkhardt, G. Rumolo
CERN, Geneva
- B. Spataro
INFN/LNF, Frascati (Roma)
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Since 2003, high-intensity single-bunch proton beams with low longitudinal emittance have been affected by heavy losses after less than one synchrotron period after injection. The effects of the resonance frequency of the responsible impedance, longitudinal emittance and chromaticity on the intensity threshold were already discussed in detail in 2004, comparing analytical predictions with simulation results. In this paper the evolution of the instability between injection and the time of beam loss is our main concern. Measurements are compared with HEADTAIL simulations. A travelling-wave pattern propagating along the bunch, which is the signature of a Beam Break-Up or Transverse Mode Coupling Instability (TMCI), is clearly identified. The oscillating frequency, near ~1 GHz, is in good agreement with the usual broad-band impedance model deduced from beam-based measurements like the head-tail growth rate vs. chromaticity.
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| THPCH061 |
Tune Shift Induced by Nonlinear Resistive Wall Wake Field of Flat Collimator
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2925 |
| |
- F. Zimmermann, G. Arduini, R.W. Assmann, H. Burkhardt, F. Caspers, M. Gasior, O.R. Jones, T. Kroyer, E. Métral, S. Redaelli, G. Robert-Demolaize, F. Roncarolo, G. Rumolo, R.J. Steinhagen, J. Wenninger
CERN, Geneva
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We present formulae for the coherent and incoherent tune shifts due to the nonlinear resistive wall wake field for a single beam traveling between two parallel plates. In particular, we demonstrate that the nonlinear terms of the resistive wall wake field become important if the gap between the plates is comparable to the transverse rms beam size. We also compare the theoretically predicted tune shift as a function of gap size with measurements for an LHC prototype graphite collimator in the CERN SPS and with simulations.
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