Paper |
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MOPJE045 |
Fixed Points in Presence of Space Charge in Circular Particle Accelerators |
389 |
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- M. Giovannozzi, S.S. Gilardoni, A. Huschauer
CERN, Geneva, Switzerland
- S. Machida, C.R. Prior, S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
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Recent measurements performed in the framework of the multi-turn extraction (MTE) studies showed a dependence of the position of beamlets obtained by crossing a stable transverse resonance on the total beam intensity. This novel observation has triggered a number of studies aiming at understanding the source of the observed effect. In this paper the results of numerical simulations performed in different conditions are discussed in detail.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE045
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MOPJE046 |
Influence of the Alignment of the Main Magnets on Resonances in the CERN Proton Synchrotron |
392 |
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- A. Huschauer, S.S. Gilardoni, R. Wasef
CERN, Geneva, Switzerland
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During the Long Shutdown 1 seven out of the one hundred combined function PS main magnets were removed from the tunnel to conduct maintenance. After reinstallation, the main magnets were aligned to the reference positions and within the first week of operation of the accelerator, a beam-based re-alignment campaign was performed to reduce the excursions of the closed orbit. In order to further investigate and understand the source of betatronic resonances, which, already in 2011, were found to be excited by the bare machine, tune diagram measurements before and after this beam-based magnet alignment were conducted. In both cases the same resonances as in 2011 were found to be present; however, after the alignment, an overall increase of their strengths was observed. In this paper we present the corresponding measurement results and discuss the direct impact on the daily operation of the accelerator.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE046
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MOPJE047 |
Chromaticity Dependence of the Transverse Effective Impedance in the CERN Proton Synchrotron |
395 |
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- S. Persichelli, N. Biancacci, S.S. Gilardoni, A. Huschauer, E. Métral, B. Salvant, R. Wasef
CERN, Geneva, Switzerland
- M. Migliorati
University of Rome La Sapienza, Rome, Italy
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The current knowledge of the transverse impedance of the Proton Synchrotron (PS) has been established with beam-based measurements at different energies. The transverse coherent tune shift as a function of the beam intensity has been measured in order to evaluate the total effective imaginary part of the transverse impedance and its localization in the accelerator at the energies of 2, 7, 13 and 25 GeV. Measurements have been performed changing the chromaticity for every tune shift scan with intensity. The data analysis revealed an increase of impedance with chromaticity for all the energies considered. That transverse impedance can be compared with the previously evaluated theoretical impedance budget taking into account the individual contribution of several machine devices. The missing impedance is finally highlighted.
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DOI • |
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※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE047
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MOPJE048 |
Electron-Cloud Studies for Transversely Split Beams |
399 |
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- N. Pradhan, S.S. Gilardoni, M. Giovannozzi, G. Iadarola, G. Rumolo
CERN, Geneva, Switzerland
- N. Pradhan
UMiss, University, Mississippi, USA
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Recently, resonance crossing has been proposed as a means of manipulating the transverse beam distribution. This technique has application, among other topics, to injection and extraction schemes. Moreover, the transversely split beams might also be used as a mitigation measure of electron-cloud effects. The results of detailed numerical simulations are discussed in this paper, possibly opening new options for scrubbing of beam pipes in circular accelerators.
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DOI • |
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※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE048
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MOPJE071 |
New Electron Cloud Detectors for the CERN Proton Synchrotron |
476 |
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- C. Yin Vallgren, P. Chiggiato, S.S. Gilardoni, H. Neupert, M. Taborelli
CERN, Geneva, Switzerland
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Electron cloud (EC) has already been observed during normal operation of the PS using classical shielded button pick-up detectors in drift sections. In the context of the LHC Injector Upgrade (LIU project), similar measurements are also needed for the combined function magnets of the machine, where the access to the vacuum chamber is strongly limited by the presence of the yoke. Two new electron cloud detectors have been studied, developed, and installed during the Long Shutdown (LS1) in one of such magnets. The first is based on current measurement by using a shielded button-type pick-up with a special geometry to reach the bottom surface of the vacuum pipe embedded in the magnet. The second one relies on a newly developed measurement method based on detection of the photons, which are emitted by cathodoluminescence from the electron cloud impinging on the vacuum chamber walls. Part of the emitted photons is collected through a quartz window by a Micro-Channel Plate Photomultiplier Tube (MCP-PMT). First results obtained during machine development runs show the feasibility of the photon detection scheme. The results are discussed and compared with pick-up measurements.
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DOI • |
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※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE071
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THPF093 |
Status of the LHC Injectors Upgrade (LIU) Project at CERN |
3915 |
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- M. Meddahi, J. Coupard, H. Damerau, A. Funken, S.S. Gilardoni, B. Goddard, K. Hanke, L. Kobzeva, A.M. Lombardi, D. Manglunki, S. Mataguez, B. Mikulec, G. Rumolo, E.N. Shaposhnikova, M. Vretenar
CERN, Geneva, Switzerland
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CERN is currently carrying out an ambitious improvement programme of the full LHC Injectors chain in order to enable the delivery of beams with the challenging HL-LHC parameters. The LHC Injectors Upgrade project coordinates this massive upgrade program, and covers a new linac (Linac4 project) as well as upgrades to the Proton Synchrotron Booster, the Proton Synchrotron and Super Proton Synchrotron. The heavy ion injector chain is also included, adding the Linac3 and Low Energy Ion Ring to the list of accelerators concerned. The performance objectives and roadmap of the main upgrades will be presented, including the work status and outlook. The machine studies and milestones during LHC Run 2 will be discussed and a preliminary Long Shutdown 2 installation planning given. Finally, for the LHC Run 3, the beam performance across the full injector chain after all the upgrades will be estimated and the required commissioning stages outlined.
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DOI • |
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※ https://doi.org/10.18429/JACoW-IPAC2015-THPF093
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THPF099 |
Upgrade of the SPS Ion Injection System |
3938 |
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- J.A. Uythoven, J. Borburgh, E. Bravin, S. Burger, E. Carlier, J.-M. Cravero, L. Ducimetière, S.S. Gilardoni, B. Goddard, J. Hansen, E.B. Holzer, M. Hourican, T. Kramer, F.L. Maciariello, D. Manglunki, F.-X. Nuiry, A. Perillo Marcone, G.E. Steele, F.M. Velotti, H. Vincke
CERN, Geneva, Switzerland
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As part of the LHC Injectors Upgrade Project (LIU) the injection system into the SPS will be upgraded for the use with ions. The changes will include the addition of a Pulse Forming Line parallel to the existing PFN to power the kicker magnets MKP-S. With the PFL a reduced magnetic field rise time of 100 ns should be reached. The missing deflection strength will be given by two new septum magnets MSI-V, to be installed between the existing septum MSI and the kickers MKP-S. A dedicated ion dump will be installed downstream of the injection elements. The parameter lists of the elements and studies concerning emittance blow-up coming from the injection system are presented. The feasibility of the 100 ns kicker rise time and the small ripple of the septum power converter are presented. Material studies of the ion dump are presented together with the radiation impact.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2015-THPF099
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