Wake and higher order mode computations for the CMS experimental chamber at the LHC (2009)
Wakefields and trapped Higher Order Modes (HOMs) in the CMS experimental chamber at the LHC are investigated using a geometrical model which closely reflects the presently installed vacuum chamber....
A New CERN PS Transverse Damper (2009)
Blas, A, Belleman, J M, Benedetto, E, Caspers, F, Glenat, D C, Louwerse, R, ...
Since 1999 the PS has been operated without active transverse damping thanks to an increase of the coupling between the transverse planes and the reduction of injection steering errors. Although the...
Accelerator physics concept for upgraded LHC collimation performance (2009)
Assmann, R, Bellodi, G, Jowett, J, Métral, E, Weiler, T, Markiewicz, T, ...
The LHC collimation system is implemented in phases, in view of the required extrapolation by 2-3 orders of magnitude beyond Tevatron and HERA experience in stored energy. All available simulations...
An update of Zbase, the CERN impedance database (2009)
Salvant, B, Medina, H, Métral, E, Rumolo, G
A detailed knowledge of the beam coupling impedance of the CERN synchrotrons is required in order to identify the impact on instability thresholds of potential changes of beam parameters, as well as...
Analysis of the transverse SPS Beam coupling impedance with short and long bunches (2009)
Salvant, B, Calaga, R, De-Maria, R, Arduini, Gianluigi, Burkhardt, H, Damerau, H, ...
The upgrade of the CERN Large Hadron Collider (LHC) would require a four- to fivefold increase of the single bunch intensity presently obtained in the Super Proton Synchrotron (SPS). Operating at...
Status of LHC Crab Cavity simulations and beam studies (2009)
Calaga, R, De-Maria, R, Assmann, R, Barranco, J, Caspers, F, Ciapala, Edmond, ...
The LHC crab cavity program is advancing rapidly towards a first prototype which is anticipated to be tested during the early stages of the LHC phase I upgrade and commissioning. The general project...
Controlled Transverse Emittance Blow-up in the CERN SPS (2009)
Métral, E, Arduini, Gianluigi, Arnold Malandain, F, Höfle, Wolfgang, Manglunki, D
For several years, a large variety of beams have been prepared in the LHC injectors, such as single-bunch and multi-bunch beams, with 25 ns, 50 ns and 75 ns bunch spacings, nominal and intermediate...
Impedance Studies for the Phase 2 LHC Collimators (2009)
Métral, E, Caspers, F, Grudiev, A, Kroyer, T, Zotter, B, Roncarolo, F, ...
The LHC phase 2 collimation project aims at gaining a factor ten in cleaning efficiency, robustness and impedance reduction. From the impedance point of view, several ideas emerged during the last...
Barnes, M J, Caspers, F, Kroyer, T, Métral, E, Roncarolo, F, Salvant, B
Fast kicker magnets are used to inject beam into and eject beam out of the CERN SPS accelerator ring. These kickers are generally ferrite loaded transmission line type magnets with a rectangular...
Carbon Fiber Damage in Accelerator Beam (2009)
Sapinski, M, Dehning, B, Guerrero, A, Koopman, J, Métral, E
Carbon fibers are commonly used as moving targets in Beam Wire Scanners. Because of their thermomechanical properties they are very resistant to particle beams. Their strength deteriorates with time...
Ions for LHC: Towards Completion of the Injector Chain (2008)
Manglunki, Django, Albert, M, Angoletta, M E, Arduini, Gianluigi, Baudrenghien, P, Bellodi, G, ...
The commissioning of CERN's ion injector complex [1] to allow 1.1 PeV collisions of ions in LHC is well under way. After the Low Energy Ion Ring (LEIR) in 2005 [2] and the Proton Synchrotron (PS) in...
Gamma Transition Jump for PS2 (2008)
Bartmann, W, Benedikt, M, Métral, E, Möhl, D, Peggs, S
The PS2, which is proposed as a replacement for the existing ~50-year old PS accelerator, is presently considered to be a normal conducting synchrotron with an injection kinetic energy of 4 GeV and a...
Salvant, B, Arduini, Gianluigi, Calaga, R, Jones, R, Métral, E, Papotti, G, ...
Since 2003, single bunches of protons with high intensity (1.2e11 protons) and low longitudinal emittance (0.2 eVs) have been observed to suffer from heavy losses in less than one synchrotron period...
Experimental Study of the Electron Cloud Instability at the CERN SPS (2008)
Rumolo, G, Arduini, Gianluigi, Benedetto, E, Calaga, R, Métral, E, Papotti, G, ...
The electron cloud instability limits the performance of many existing proton and positron rings. A simulation study carried out with the HEADTAIL code revealed that the threshold for its onset...
Roncarolo, F, Caspers, F, Kroyer, T, Métral, E, Salvant, B
The prediction of the resistive wall transverse beam impedance at the first unstable betatron line (8 kHz) of the CERN Large Hadron Collider (LHC) is of paramount importance for understanding and...
Salvant, B, Caspers, F, Kroyer, T, Métral, E, Roncarolo, F
The low frequency longitudinal and transverse impedances of the CERN Large Hadron Collider (LHC) have to be specifically minimized to prevent the onset of coherent instabilities. The LHC beam vacuum...
CERN SPS Impedance in 2007 (2008)
Métral, E, Arduini, Gianluigi, Bohl, T, Burkhardt, H, Calaga, R, Caspers, F, ...
Each year several measurements of the beam coupling impedance are performed in both longitudinal and transverse planes of the CERN Super Proton Synchrotron to keep track of its evolution. In...
Koutchouk, Jean-Pierre, Assmann, Ralph Wolfgang, Métral, E, Todesco, E, Zimmermann, F, De Maria, R, ...
A significant reduction of b* requires a new beam crossing scheme to overcome the consequence of the luminosity loss factor. We define in this paper the parameters of a possible solution taking...
August 2008IONS FOR LHC: TOWARDS COMPLETION OF THE INJECTOR CHAIN (2008)
J. M. Jowett, V. Kain, D. Küchler, M. Martini, S. Maury, E. Métral, ...
The commissioning of CERN’s ion injector complex [1] to allow 1.1 PeV collisions of ions in LHC is well under way. After the Low Energy Ion Ring (LEIR) in 2005 [2] and the Proton Synchrotron (PS)...
Nominal LHC Beam Instability Observations in the CERN Proton Synchrotron (2007)
Steerenberg, R, Arduini, Gianluigi, Benedetto, E, Blas, A, Höfle, Wolfgang, Métral, E, ...
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...
Space-Charge Compensation Options for the LHC Injector Complex (2007)
Aiba, M, Chanel, M, Dorda, U, Franchetti, G, Garoby, R, Koutchouk, Jean-Pierre, ...
Space-charge effects have been identified as the most serious intensity limitation in the CERN PS and PS Booster, on the way towards ultimate LHC performance and beyond. We here explore the...
Transverse Impedance of LHC Collimators (2007)
Métral, E, Arduini, Gianluigi, Assmann, Ralph Wolfgang, Boccardi, A, Bracco, C, Bohl, T, ...
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...
Resistive-Wall Impedance of an Infinitely long Multi-Layer Cylindrical Beam Pipe (2007)
Métral, E, Salvant, B, Zotter, B
The resistive-wall impedance of cylindrical vacuum chambers was first calculated more than forty years ago under some approximations. Since then many papers have been published to extend its range of...
A New Type of distributed Enamel based Clearing Electrode (2007)
Kroyer, T, Behler, F J, Caspers, F, Hellmond, P, Métral, E, Wendel, J C, ...
Clearing electrodes can be used for electron cloud (EC) suppression in high intensity particle accelerators. In this paper the use of low and highly resistive layers on a dielectric substrate are...
Tracking Study of the Effect of BPM Impedances in the SPS (2007)
Rumolo, G, Arduini, Gianluigi, Métral, E, Spataro, B
Following the observation of a Transverse Mode Coupling Instability (TMCI) in the SPS [1, 2], a systematic estimate of the impedance of the various pieces of equipment installed in the machine has...
Fast Vertical Single-bunch Instability at Injection in the CERN SPS: An Update (2007)
Arduini, Gianluigi, Bohl, T, Burkhardt, H, Métral, E, Rumolo, G, Salvant, B
Following the first observation of a fast vertical instability for a single high-brightness bunch at injection in the SPS in 2002, a series of detailed measurements and simulations has been performed...
Métral, E, Rumolo, G, Salvant, B, Steerenberg, R
For many years, a horizontal head-tail instability has been observed at the CERN Proton Synchrotron during the long 1.2 s injection flat-bottom. This slow instability has been damped using linear...
Gilardoni, S S, Giovannozzi, M, Martini, M, Métral, E, Steerenberg, R, Müller, A-S
Recently, a novel technique to perform multi-turn extraction from a circular particle accelerator was proposed. It is based on beam splitting and trapping, induced by a slow crossing of a nonlinear...
Burnet, Jean Paul, Giovannozzi, Massimo, Métral, E, Michels, O, Steerenberg, R, Vandorpe, B
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...
Simulation study on the energy dependence of the TMCI threshold in the CERN-SPS (2006)
Rumolo, Giovanni, Métral, E, Shaposhnikova, Elena
This paper concentrates on theoretical studies of Transverse Mode Coupling Instability (TMCI) at the SPS. It shows the expected thresholds based on the HEADTAIL tracking model and on impedance values...
Tune shift induced by nonlinear resistive wall wake field of flat collimator (2006)
Zimmermann, Frank, Arduini, Gianluigi, Assmann, R W, Burkhardt, H, Caspers, F, Gasior, M, ...
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...
The final collimation system for the LHC (2006)
Assmann, R W, Aberle, O, Bellodi, G, Bertarelli, A, Bracco, C, Braun, H, ...
The LHC collimation system has been re-designed over in order to address the unprecedented challenges that are faced with the 360 MJ beams at 7 TeV. The layout of the LHC has now been frozen and a...
Resonant Multi-Turn Extraction: Principle and Experiments (2006)
Gilardoni, S S, Giovannozzi, Massimo, Martini, M, Métral, E, Scaramuzzi, P, Steerenberg, R, ...
Recently a novel approach to perform multi-turn extraction was proposed based on beam splitting in the transverse phase space by means of trapping inside stable islands. In addition to numerical...
1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main...
Métral, E, Giovannozzi, Massimo, Martini, M, Steerenberg, R, Franchetti, Giuliano, Hofmann, I
Several benchmarking space charge experiments have been performed during the last few years in the CERN Proton Synchrotron. These controlled experiments are of paramount importance to validate the...
Transverse resistive-wall impedance from very low to very high frequencies (2005)
The transverse resistive-wall impedance of a circular beam pipe derived from field matching in Ref. [1] is extended here, following exactly the same approach, but(i) without making the...
Overview of Impedance and Single-Beam Instability Mechanisms (2005)
The transverse resistive-wall impedance is discussed in the particular case of the LHC collimators, which reveal a new physical regime. Single-bunch and coupled-bunch instability mechanisms are then...
Final Results from the Novel Multi-turn Extraction Studies at CERN Proton Synchrotron (2005)
Cappi, R, Gilardoni, S S, Giovannozzi, Massimo, Martini, M, Métral, E, Müller, A S, ...
Recently a novel approach to perform multi-turn extraction was proposed based on beam splitting in the transverse phase space by means of trapping inside stable islands. An experimental campaign was...
Transverse Mode-Coupling Instability in the CERN Super Proton Synchrotron (2005)
Arduini, Gianluigi, Benedetto, Elena, Burkhardt, H, Métral, E, Rumolo, Giovanni, Shaposhnikova, Elena
A vertical single-bunch instability has been observed in 2003 right after injection at 26 GeV/c in the CERN Super Proton Synchrotron (SPS). High-intensity proton bunches (~1.2 1011 p/b) with low...
Long Term Simulations of Space Charge and Beam Loss Observed in the CERN Proton Synchrotron (2005)
Franchetti, Giuliano, Giovannozzi, Massimo, Hofmann, I, Martini, M, Métral, E
Long term storage of high intensity beams with small loss is required in the FAIR [1] project at GSI as well as for JPARC [2]. In this paper we discuss that an important contribution to the loss in...
Franchetti, Giuliano, Giovannozzi, Massimo, Hofmann, I, Martini, M, Métral, E, Qiang, J, ...
Measurements of emittance exchange due to the Montague resonance in the CERN Proton Synchrotron in 2003 have provided detailed data, which are suitable for benchmarking of different simulation codes...
Space-Charge Experiments at the CERN Proton Synchrotron (2005)
Franchetti, Giuliano, Giovannozzi, Massimo, Hofmann, I, Martini, M, Métral, E, Qiang, J, ...
Benchmarking of the simulation codes used for the design of the next generation of high beam power accelerators is of paramount importance due to the very demanding requirements on the level of beam...
Proton Drivers for Neutrino Factories: The CERN Approach (2000)
H. Schönauer, B. Autin, M. Chanel, G. Franchetti, J. Gareyte, R. Garoby, ...
This article concentrates on the accumulator and compressor rings of the CERN Reference Scenario; the SPL was presented at this Workshop by R. Garoby and is well-documented [1]. Only a section is...