| Paper |
Title |
Page |
| 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 |
| |
- 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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| WEPCH092 |
Dynamical Aperture Studies for the CERN LHC: Comparison between Statistical Assignment of Magnetic Field Errors and Actual Measured Field Errors
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2128 |
| |
- M. Giovannozzi, S.D. Fartoukh, S.S. Gilardoni, J.-B. Jeanneret, A.M. Lombardi, Y. Papaphilippou, T. Risselada, R. de Maria
CERN, Geneva
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It is customary to evaluate the performance of a circular particle accelerator by computing the dynamical aperture, i.e., the domain in phase space where bounded single-particle motion occurs. In the case of the LHC the dynamical aperture computation is performed by assuming a statistical distribution of the magnetic field errors of various magnets' classes: the numerical computations are repeated for a given set of realisations of the LHC ring. With the progress in the magnet production and allocation of the available positions in the ring, the statistical approach has to be replaced by the computation of one single configuration, namely the actual realisation of the machine. Comparisons between the two approaches are presented and discussed in details.
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| WEPCH139 |
WISE: An Adaptative Simulation of the LHC Optics
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2248 |
| |
- P. Hagen, M. Giovannozzi, J.-P. Koutchouk, T. Risselada, S. Sanfilippo, E. Todesco, E.Y. Wildner
CERN, Geneva
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The LHC beam dynamics requires a tight control of the magnet field quality and geometry. As the production of the magnets advances, decisions have to be made on the acceptance of possible imperfections. To ease decision making, an adaptative model of the LHC optics has been built, based on the current information available (e.g. magnetic measurements at warm or cold, magnet allocation to machine slots) as well as on statistical evaluations for the missing information (e.g. magnets yet to be built, measured, or for non-allocated slots). The uncertainties are included: relative and absolute measurement errors, warm-to-cold correlations for the fraction of magnets not measured at cold, hysteresis and power supply accuracy. A pre-processor generates instances of the LHC ring for the MADX program, with the possibility of selecting various error sources. A post-processor computes ranges for relevant beam optics parameters and distributions. This approach has been applied to the expected beta-beating, to the possible impact of permeability issues in some quadrupole collars, to the geometrical displacements of the multipolar correctors and to prioritize the magnetic measurement programme.
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