Caspers, F, Kroyer, K, Mahner, C, Wendel, JC
During the 2007 run with the nominal LHC proton beam, electron cloud has been clearly identified and characterized in the PS using a dedicated setup with shielded button-type pickups. Efficient...
Stabilizing effect of a double-harmonic RF system in the CERN PS (2009)
Bhat, C, Caspers, F, Damerau, H, Hancock, S, Mahner, E, Zimmermann, F
Motivated by the discussions on scenarios for LHC upgrades, beam studies on the stability of flat bunches in a double-harmonic RF system have been conducted in the CERN Proton Synchrotron (PS)....
Interactions of Microwaves and Electron Clouds (2009)
The modification of microwave signals passing through an electron cloud can be used as a diagnostic tool for detecting its presence and as a measure for its effective density. This observation method...
Schottky Diagnostics in the ANKA Storage Ring (2009)
Caspers, F, Sonnad, K G, Birkel, I, Casalbuoni, S, Huttel, E, Smale, N J, ...
The status of longitudinal and transverse Schottky observation systems for the synchrotron light source ANKA is presented. ANKA regularly operates in a dedicated low alpha mode with short bunches for...
Trapped Mode Study in the LHC Rotatable Collimator (2009)
Xiao, L, Ng, C K, Smith, J C, Caspers, F
A rotatable collimator is proposed for the LHC phase II collimation upgrade. When the beam crosses the collimator, trapped modes will be excited that result in beam energy loss and collimator power...
A Novel Technique for Mitigating Multipactor by Means of Magnetic Surface Roughness (2009)
Caspers, F, Montesinos, E, Boria, V E, Bruns, W, Galan, L, Gimeno, B, ...
Multipactor phenomena which are closely linked to the SEY (secondary electron yield)can be mitigated by many different methods including groves in the metal surface as well as using electric or...
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...
Kotzian, G, Caspers, F, Federmann, S, Höfle, Wolfgang, Kotzian, G, De Maria, R
In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated...
Stabilizing Effect of a Double-Harmonic RF System in the CERN PS (2009)
Bhat, C M, Caspers, F, Damerau, H, Hancock, S, Mahner, E, Zimmermann, F
Motivated by the discussions on scenarios for LHC upgrades, beam studies on the stability of flat bunches in a double-harmonic RF system have been conducted in the CERN Proton Synchrotron (PS)....
Coupling Impedance of the CERN SPS beam position monitors (2009)
Salvant, B, Arduini, G, Boccard, C, Caspers, F, Grudiev, A, Jones, R, ...
A detailed knowledge of the beam coupling impedance of the CERN Super Proton Synchrotron (SPS) is required in order to operate this machine with a higher intensity for the foreseen Large Hadron...
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...
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, Cornelis, K, Ducimetière, L, Mahner, E, Papotti, G, ...
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...
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...
Caspers, F, Jaeckel, J, Ringwald, A
Using microwave cavities one can build a resonant “light-shining-through-walls” experiment to search for hidden sector photons and axion like particles, predicted in many extensions of the...
Orthogonal Coupling in Cavity BPM with Slots (2009)
Lipka, D, Nölle, D, Siemens, M, Vilcins, S, Caspers, F, Stadler, M, ...
XFELs require high precision orbit control in their long undulator sections. Due to the pulsed operation of drive linacs the high precision has to be reached by single bunch measurements. So far only...
For non-invasive determination of the spatial power density distribution during RF- and microwave hyperthermia it is proposed to apply the electromagnetic energy as short, high intensity pulses. This...
Measurements of the Electron Cloud Density in the PEP-II Low Energy Ring (2009)
Byrd, J, De Santis, S, Sonnad, K, Caspers, F, Kroyer, T, Krasnykh, A, ...
Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of...
Caspers, F, Federmann, S, Höfle, Wolfgang, Kotzian, G, De Maria, R
In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated...
BEAM INDUCED HEATING OF THE SPS FAST PULSED MAGNETS (2009)
J. Uythoven, G. Arduini, T. Bohl, F. Caspers, E. H. Gaxiola, T. Kroyer, ...
Fast pulsed magnets with ferrite yokes are used in CERN’s SPS accelerator for beam injection, extraction and excitation for tune measurements. The impedance of the ferrite structures can provoke...
Pivi, M T F, Krasnykh, A K, Byrd, J, De Santis, S, Sonnad, K G, Caspers, F, ...
Clouds of electrons in the vacuum chambers of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of...
Beam-Induced Multipactoring and Electron-Cloud Effects in Particle Accelerators (2009)
Caspers, F, Rumolo, G, Scandale, Walter, Zimmermann, F
In the beam pipe of high-energy proton or positron accelerators an “electron cloud” can be generated by a variety of processes, e.g. by residual-gas ionization, by photoemission from synchrotron...
F. Caspers, DESY Forschung Hochenergiephysik, J. Jaeckel, A. Ringwald
Internal report | Preprint
Sonnad, K.G., Müller, A.S., Caspers, F., Mashkina, E., Smale, N.J., ...
23rd Particle Accelerator Conf. (PAC09), Vancouver, CDN, May 4-8, 2009
Schottky diagnostics in the ANKA storage ring. (2009)
Sonnad, K.G., Müller, A.S., Caspers, F., Smale, N.J., Birkel, I., Casalbuoni, S., ...
23rd Particle Accelerator Conf. (PAC09), Vancouver, CDN, May 4-8, 2009
F. Caspers, DESY Forschung Hochenergiephysik, J. Jaeckel, A. Ringwald
Journal article
Orthogonal Coupling in Cavity BPM with Slots. 2009-05-25 - 2009-05-27 (2009)
D. Lipka, DESY Maschinenphysik, D. Noelle, M. Siemens, S. Vilcins, ...
Contribution to a conf. proceeding (book/online)
Beam Coupling Impedance Measurement and Mitigation for a Totem Roman Pot (2008)
Deile, M, Caspers, F, Kroyer, T, Oriunno, M, Radermacher, E, Roncarolo, F, ...
The longitudinal and transverse beam coupling impedance of the first final TOTEM Roman Pot unit has been measured in the laboratory with the wire method. For the evaluation of transverse impedance...
Albertone, J, Bartolome-Jimenez, S, Boccard, C, Bogey, T, Borowiec, P, Calvo, E, ...
Ensuring that the two 27km beam pipes of the LHC do not contain aperture restrictions is of utmost importance. Most of the ring is composed of continuous cryostats, so any intervention to remove...
Experimental Electron Cloud Studies in the CERN Proton Synchrotron (2008)
Mahner, E, Kroyer, T, Caspers, F
Indications for a beam-induced electron cloud build-up are observed since 2000 for the nominal LHC beam in the PS to SPS transfer line and during the last turns before ejection from the PS. A new...
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...
RF Wire Compensator of Long-Range Beam-Beam Effects (2008)
Dorda, U, Caspers, F, Kroyer, T, Zimmermann, F
The dynamic aperture of the proton beam circulating in the Large Hadron Collider (LHC) is expected to be limited by up to 120 long-range beam-beam encounters. In order to perfectly compensate the LHC...
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...
PRACTICAL INSTRUCTIONS FOR THE RF AND MICROWAVE MEASUREMENT TUTORIAL (2008)
For this practical tutorial using (vector) network and spectrum analysers detailed instructions are given on how to operate these sophisticated instruments, avoiding the need for reading heavy...
Measurement of Electron Clouds in Large Accelerators by Microwave Dispersion (2008)
De Santis, S, Byrd, JM, Caspers, F, Krasnykh, A, Kroyer, T, Pivi, MTF, ...
Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult...
Characterization of the ATLAS Roman Pots Beam Coupling Impedance and Mechanics (2008)
Roncarolo, F, Caspers, F, Di Girolamo, B, Jones, RM, Kroyer, T
Neutralisation Of The Lear Electron-Cooling Beam: Experimental Results (2007)
Bosser Caspers Chanel, J. Bosser, F. Caspers, M. Chanel, R. Ley, R. Maccaferri, ...
This paper reports on the technological aspects, the measurement techniques and the results. I. INTRODUCTION
F. Caspers, W. Heinze, J. Lewis, M. Lindroos, T. Salvermoser
Longitudinal and transverse beam control in circular accelerators depends critically on a reliable real-time knowledge of the magnetic bending field. Traditionally this is achieved with a...
F. Caspers, A. Mostacci, H. Tsutsui
In this paper we discuss longitudinal beam coupling impedance measurements performed with the coaxial wire method on a modified prototype of the SPS MKE kicker. The frequency dependent real and...
The 4.8 GHz LHC Schottky Pick-up System (2007)
Caspers, F, Hamerla, T, Jansson, A, Jiménez, J M, Jones, O R, Kroyer, T, ...
The LHC Schottky observation system is based on traveling wave type high sensitivity pickup structures operating at 4.8 GHz. The choice of the structure and operating frequency is driven by the...
Caspers, F, Kroyer, T, Kulka, J, Tock, J-P, Williams, L R
As part of the LHC assembly program, the super-conducting magnets are interconnected after installation. Electrical continuity between the magnets is ensured via a specifically designed cable...
The LHC Beam Pipe Waveguide Mode Reflectometer (2007)
Kroyer, T, Borowiec, P, Caspers, F, Sulek, Z, Williams, L R
The waveguide-mode reflectometer for obstacle detection in the LHC beam pipe has been intensively used for more than 18 months. The âﾜAssemblyâ version is based on the synthetic pulse...
An Improved Beam Screen for the LHC Injection Kickers (2007)
Barnes, M J, Caspers, F, Ducimetière, L, Garrel, N, Kroyer, T
The two LHC injection kicker magnet systems must produce a kick of 1.3 T.m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. Each...
Joint CARE-ELAN, CARE-HHH-APD, and EUROTEV-WP3 Workshop on Electron Cloud Clearing (2007)
Caspers, F, Scandale, Walter, Schulte, D, Zimmermann, F
This report contains the Proceedings of the joint CARE-HHH-APD, CARE-ELAN, and EUROTEV-WP3 Mini-Workshop on 'Electron Cloud Clearing - Electron Cloud and Technical Consequences', "ECL2", held at CERN...
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...
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...
The CERN SPL Chopper Structure. A Status Report (2007)
Kroyer, T, Caspers, F, Mahner, E
In the framework of HIPPI, a study for a Superconducting Proton Linac is being carried out at CERN. An integral part of the medium energy line is the chopper, which has to establish the required time...
Transverse impedance of LHC collimators (2007)
Metral, E, Arduini, G, Assmann, R, Boccardi, A, Bohl, T, Caspers, F, ...
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...
Linac4 Technical Design Report (2006)
Arnaudon, L, Baudrenghien, P, Baylac, M, Bellodi, G, Body, Y, Borburgh, J, ...
Linac4 is an H- linear accelerator, intended to replace Linac2 as injector to the PS Booster (PSB). By delivering to the PSB a beam at 160 MeV energy, Linac4 will provide the conditions to double the...
Status of the design of a Wide Band beam Current Monitor (WBCM) for EUROTeV (2006)
Caspers, F, Fandos, R, Jensen, E, Kroyer, T, Podadera-Aliseda, I, Soby, L, ...
In the framework of EUROTeV, the conceptual design of a new wide band wall current monitor is being carried out. The design is based on the wall current monitors presently installed in CTF3. The new...
The SPL (II) at CERN, a Superconducting 3.5 GeV H- Linac (2006)
Gerigk, F, Baylac, M, Bellodi, G, Benedico-Mora, E, Body, Y, Caspers, F, ...
A revision of the physics needs and recent progress in the technology of superconducting (SC) RF cavities have triggered major changes in the design of a SC H-linac at CERN. With up to 5MW beam...
Fault Detection and Identification Methods Used for the LHC Cryomagnets and Related Cabling (2006)
Bozzini, D, Caspers, F, Chareyre, V, Duse, Y, Kroyer, T, López, R, ...
Several methods for electrical fault location have been developed and tested. As part of the electrical quality assurance program for the LHC, certain wires have to be subjected to a (high) DC...
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 Beam Screen for the LHC Injection Kicker Magnets (2006)
Barnes, MJ, Caspers, F, Ducimetière, L, Garrel, N, Kroyer, T
The two LHC injection kicker magnet systems must each produce a kick of 1.2 T.m with a flattop duration variable up to 7.86 ìs, and rise and fall times of less than 0.9 ìs and 3 ìs, respectively....
The SPS Fast Extraction Kicker System in LSS6 (2006)
Gaxiola, E, Caspers, F, Ducimetière, L, Faure, P, Kroyer, T, Versolatto, B, ...
A new fast extraction has been set up in SPS LSS6 to transfer 450 GeV/c protons as well as ions to Ring 1 of the LHC, via the transfer line TI 2. The system includes four travelling wave kicker...
Operational experience with the LHC waveguide mode reflectometer (2006)
Borowiec, P, Caspers, F, Kroyer, T, Sulek, Z, Williams, L
The LHC microwave mode reflectometer (assembly version) reached operational status by the autumn of 2005. It is now routinely used in the LHC tunnel and on the surface to take data on the beam...
Impedance measurement of the SPS MKE kicker by means of the coaxial wire method (2006)
Caspers, F, González, C, Dyachkov, M, Shaposhnikova, Elena, Tsutsui, H
Proposal for a 3 MeV H¯ test facility in the PS South Hall (2006)
Bongardt, K, Caspers, F, Garoby, R, Küchler, D, Lombardi, A M, Mostacci, A, ...
Application of Waveguide Mode Diagnostics for Remote Sensing in Accelerator Beam Pipes (2005)
Kroyer, T, Scholtz, A L, Caspers, F
In this work, two remote sensing systems using waveguide modes in beam pipes of CERN accelerators are studied. The first is an application of time domain reflectometry in waveguides. Since the...
Stochastic Cooling Electrodes for a Wide Velocity Rangel in the CR (2005)
Balk, MC, Caspers, F, Franzke, B, Nolden, F, Peschke, C, Thorndahl, L, ...
The CR storage ring is part of the FAIR project at GSI.It serves as a first stage of stochastic cooling for secondary rare isotopes at v/c=0.83 as well as for antiprotons at v/c=0.97. To avoid the...
Results from the SPS 1.7 GHz travelling wave schottky monitor (2005)
Castro, M E, Caspers, F, Kroyer, T, Jones, R, Koutchouk, Jean-Pierre, Tranquille, G
A 1.7 GHz waveguide Schottky detector system was recently built and installed in the SPS accelerator following the design of the detectors of the Fermilab Tevatron and Recycler accelerators. The...
The Large Hadron Collider Vacuum System (1995)
B. Angerth, F. Bertinelli, R. Calder, F. Caspers, P. Cruikshank, ...
INTRODUCTION The two rings of the LHC beam vacuum system have a total length of about 54 km of which almost 48 km will be at 1.9 K, the temperature of the superconducting magnets [1]. With the design...