| Paper |
Title |
Page |
| MOPCH097 |
CERN Proton Synchrotron Working Point Control Using an Improved Version of the Pole-face-windings and Figure-of-eight Loop Powering
|
264 |
| |
- R.R. Steerenberg, J.-P. Burnet, M. Giovannozzi, O. Michels, E. Métral, B. Vandorpe
CERN, Geneva
|
|
| |
The working point of the CERN Proton Synchrotron, which is equipped with combined function magnets, is controlled using pole-face-windings. Each main magnet consists of one focusing and one de-focusing half-unit on which four pole-face-winding plates are mounted containing two separate coils each, called narrow and wide. At present they are connected in series, but can be powered independently. In addition, a winding called the figure-of-eight loop, contours the pole faces and crosses between the two half units, generating opposite fields in each half-unit. The four optical parameters, horizontal and vertical tune and chromaticity, are adjusted by acting on the pole-face-winding currents in both half units and in the figure-of-eight loop, leaving one physical quantity free. The power supply consolidation project opened the opportunity to use five independent power supplies, to adjust the four parameters plus an additional degree of freedom. This paper presents the results of the measurements that have been made in the five-current mode together with the influence of the magnetic nonlinearities, due to the unbalance in the narrow and wide winding currents, on the beam dynamics.
|
|
| TUPLS122 |
Implementation of the Proposed Multiturn Extraction at the CERN Proton Synchrotron
|
1789 |
| |
- M. Giovannozzi
CERN, Geneva
|
|
| |
Following the positive results of the three-year measurement campaign at the CERN Proton Synchrotron concerning beam splitting with stable islands in the transverse phase space, the study of a possible implementation of the proposed multi-turn extraction was undertaken. The novel approach would allow a substantial reduction of beam losses, with respect to the present scheme, when delivering the high-intensity proton beams required for the planned CERN Neutrino to Gran Sasso Project. Major modifications to the ring layout are foreseen, such as a new design of the extraction bumps including also the installation of three additional kickers to create a closed-bump over the five turns used to extract the split beam. The ring aperture was reviewed and improvements are proposed to reduce possible beam losses between beam splitting and extraction. The goal consists of implementing the proposed changes by the end of the 2007/2008 PS shutdown and to commission the novel extraction during the 2008 physics run.
|
|
| WEPCH047 |
Procedures and Accuracy Estimates for Beta-beat Correction in the LHC
|
2023 |
| |
- R. Tomas, O.S. Brüning, S.D. Fartoukh, M. Giovannozzi, Y. Papaphilippou, F. Zimmermann
CERN, Geneva
- R. Calaga, S. Peggs
BNL, Upton, Long Island, New York
- F. Franchi
GSI, Darmstadt
|
|
| |
The LHC aperture imposes a tight tolerance of 20% on the maximum acceptable beta-beat in the machine. An accurate knowledge of the transfer functions for the individually powered insertion quadrupoles and techniques to compensate beta-beat are key prerequisites for successful operation with high intensity beams. We perform realistic simulations to predict quadrupole errors in LHC and explore possible ways of correction to minimize beta-beat below the 20% level.
|
|
| WEPCH092 |
Dynamical Aperture Studies for the CERN LHC: Comparison between Statistical Assignment of Magnetic Field Errors and Actual Measured Field Errors
|
2128 |
| |
- M. Giovannozzi, S.D. Fartoukh, S.S. Gilardoni, J.-B. Jeanneret, A.M. Lombardi, Y. Papaphilippou, T. Risselada, R. de Maria
CERN, Geneva
|
|
| |
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.
|
|
| WEPCH093 |
Parameter Scans and Accuracy Estimates of the Dynamic Aperture of the CERN LHC
|
2131 |
| |
- M. Giovannozzi, E. McIntosh
CERN, Geneva
|
|
| |
Techniques to make use of large distributed computing facilities allow for denser parameter scans of the dynamical aperture, i.e., the domain in phase space where bounded single-particle motion prevails. Moreover, one can also increase the number of 'seeds' each of which represents a possible realisation of multipolar components around the machine. In this paper the dependence of the dynamical aperture on the step size of the grid of initial conditions and on the number of seeds is studied. Estimates on the accuracy of the dynamic aperture are derived and the definition of an improved protocol for numerical simulations is presented.
|
|
| WEPCH139 |
WISE: An Adaptative Simulation of the LHC Optics
|
2248 |
| |
- P. Hagen, M. Giovannozzi, J.-P. Koutchouk, T. Risselada, S. Sanfilippo, E. Todesco, E.Y. Wildner
CERN, Geneva
|
|
| |
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.
|
|
| THPCH059 |
Kicker Impedance Measurements for the Future Multi-turn Extraction of the CERN Proton Synchrotron
|
2919 |
| |
- E. Métral, F. Caspers, M. Giovannozzi, A. Grudiev, T. Kroyer, L. Sermeus
CERN, Geneva
|
|
| |
In the context of the novel multi-turn extraction, where charged particles are trapped into stable islands in transverse phase space, the ejection of five beamlets will be performed by means of a set of three new kickers. Before installing them into the machine, a measurement campaign has been launched to evaluate the impedance of such devices. Two measurement techniques were used to try to disentangle the driving and detuning impedances. The first consists in measuring the longitudinal impedance for different transverse offsets using a single displaced wire. The sum of the transverse driving and detuning impedances is then deduced applying Panofsky-Wenzel theorem. The second uses two wires excited in opposite phase and yields the driving transverse impedance only. Finally, the consequences on the beam dynamics are also analyzed.
|
|
| WEPCH141 |
Accelerator Physics Code Web Repository
|
2254 |
| |
- F. Zimmermann, R. Basset, E. Benedetto, U. Dorda, M. Giovannozzi, Y. Papaphilippou, T. Pieloni, F. Ruggiero, G. Rumolo, F. Schmidt, E. Todesco
CERN, Geneva
- D.T. Abell
Tech-X, Boulder, Colorado
- R. Bartolini
Diamond, Oxfordshire
- O. Boine-Frankenheim, G. Franchetti, I. Hofmann
GSI, Darmstadt
- Y. Cai, M.T.F. Pivi
SLAC, Menlo Park, California
- Y.H. Chin, K. Ohmi, K. Oide
KEK, Ibaraki
- S.M. Cousineau, V.V. Danilov, J.A. Holmes, A.P. Shishlo
ORNL, Oak Ridge, Tennessee
- L. Farvacque
ESRF, Grenoble
- A. Friedman
LLNL, Livermore, California
- M.A. Furman, D.P. Grote, J. Qiang, G.L. Sabbi, P.A. Seidl, J.-L. Vay
LBNL, Berkeley, California
- D. Kaltchev
TRIUMF, Vancouver
- T.C. Katsouleas
USC, Los Angeles, California
- E.-S. Kim
PAL, Pohang, Kyungbuk
- S. Machida
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
- J. Payet
CEA, Gif-sur-Yvette
- T. Sen
Fermilab, Batavia, Illinois
- J. Wei
BNL, Upton, Long Island, New York
- B. Zotter
Honorary CERN Staff Member, Grand-Saconnex
|
|
| |
In the framework of the CARE HHH European Network, we have developed a web-based dynamic accelerator-physics code repository. We describe the design, structure and contents of this web repository, illustrate its usage, and discuss our future plans.
|
|