Tomás, R
Kubo, K
Kuroda, S
Naito, T
Okugi, T
Urakawa, J
Zimmermann, F
Measurement of Resonance driving terms in the ATF Damping Ring
The measurement of resonance driving terms in the Damping Ring of the Accelerator Test Facility in KEK could help finding possible machine imperfections and even to optimize single particle stability through the minimization of non-linearities. The first experimental attempts of this enterprise are reported in this note.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc073.pdf;
http://cds.cern.ch/record/1122247/files/CERN-AB-2008-007_2.pdf;
http://cds.cern.ch/record/1122247/files/CERN-AB-2008-007.pdf;
Imported from Invenio.
Métral, E
Arduini, Gianluigi
Bohl, T
Burkhardt, H
Calaga, R
Caspers, Friedhelm
Damerau, H
Kroyer, T
Medina, H
Rumolo, G
Salvant, B
Schokker, M
Shaposhnikova, E
Spataro, B
Tückmantel, Joachim
CERN SPS Impedance in 2007
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 parallel, after the extensive and successful campaign of identification, classification and cure of the possible sources of (mainly longitudinal) impedance between 1998 and 2001, a new campaign (essentially for the transverse impedance this time) has started few years ago, in view of the operation of the SPS with higher intensity for the LHC luminosity upgrade. The present paper summarizes the results obtained from the measurements performed over the last few years and compares them to our predictions. In particular, it reveals that the longitudinal impedance is reasonably well understood and the main contributors have already been identified. However, the situation is quite different in the transverse plane: albeit the relative evolution of the transverse impedance over the last few years can be well explained by the introduction of the nine MKE kickers necessary for beam extraction towards the LHC, significant contributors to the SPS transverse impedance have not been identified yet.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupp066.pdf;
http://cds.cern.ch/record/1122256/files/CERN-AB-2008-008.pdf;
Imported from Invenio.
Giovannozzi, M
Quatraro, D
Turchetti, G
Stability change of Fourth-Order Resonance with application to Multi-Turn Extraction Schemes
Recently, a novel multi-turn extraction scheme was proposed, based on particle trapping inside stable resonances. Numerical simulations and experimental tests conirmed the feasibility of such a scheme for low order resonances. While the 3rd order resonance is generically unstable and those higher than 4th order are generically stable, the 4th order resonance can be either stable or unstable depending on the details of the system under consideration. By means of the normal form approach a general formula to control the stability of the 4th order resonance is derived. Numerical simulations confirm the analytical results and show that by crossing the unstable 4th order resonance the region around the centre of phase space is depleted and particles are trapped only in the four stable islands. This indicates that a four-turn extraction could be envisaged based on this technique.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc056.pdf;
http://cds.cern.ch/record/1122260/files/CERN-AB-2008-009.pdf;
Imported from Invenio.
Barranco, J
Bartmann, W
Benedikt, M
Papaphilippou, Y
Beam Losses and Collimation Considerations for PS2
The high intensity beams with different emittances foreseen to be delivered by the PS2, an upgraded version of the actual CERN Proton Synchrotron, require strict control of beam losses in order to protect the machine components and enable their hands-on maintenance. Beam loss simulations based on dedicated numerical tools are undertaken for a variety of PS2 beams and for different loss mechanisms, along the whole accelerating cycle. In this respect, a first iteration of the collimation system is presented.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc052.pdf;
http://cds.cern.ch/record/1122261/files/CERN-AB-2008-010.pdf;
Imported from Invenio.
Latina, A
Schulte, D
Tomás, R
Alignment of the CLIC BDS
Aligning the CLIC Beam Delivery System faces two major challenges, the tight tolerances for the emittance preservation and its strong non-linear beam dynamics. For these reasons conventional beam-based alignment techniques, like dispersion free steering, are only partially successful and need to be followed by optimization algorithms based on other observables, like beam sizes.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp037.pdf;
http://cds.cern.ch/record/1122289/files/CERN-AB-2008-011.pdf;
Imported from Invenio.
Jeanneret, J B
Braun, H H
Optimisation of a Beam Transfer FODO Line
With in view the design of the CLIC long transfer lines, we develop a formal approach for the optimisation of a straight FODO line. Optimum phase advance and cell length depending on beam parameters are derived for power consumption, overall cost and sensitivity to quadrupole misalignment.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc017.pdf;
http://cds.cern.ch/record/1122291/files/CERN-AB-2008-012.pdf;
Imported from Invenio.
Adli, E
Schulte, D
Beam-Based Alignment for the CLIC Decelerator
The CLIC Drive Beam decelerator requires the beam to be transported with very small losses. Beam-based alignment is necessary in order to achieve this, and various beam-based alignment schemes have been tested for the decelerator lattice. The decelerator beam has an energy spread of up to 90%, which impacts the performance of the alignment schemes. We have shown that Dispersion-Free-Steering works well for the decelerator lattice. However, because of the transverse focusing approach, modifications of the normal DFS schemes must be applied. Tune-up scenarios for the CLIC decelerator using beam-based alignment are also discussed.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp001.pdf;
http://cds.cern.ch/record/1122730/files/CERN-AB-2008-013.pdf;
Imported from Invenio.
Adli, E
Schulte, D
Syratchev, I
A study of Failure Modes in the CLIC Decelerator
The CLIC Drive Beam decelerator is responsible for producing the RF power for the main linacs, using Power Extraction and Transfer Structures (PETS). To provide uniform power production, the beam must be transported with very small losses. In this paper failure modes for the operation of the decelerator are investigated, and the impact on beam stability and loss levels is presented. Quadrupole failure, PETS inhibition and PETS RF break down scenarios are being considered.
eng
2008
https://accelconf.web.cern.ch/e08/papers/MOPP002.pdf;
http://cds.cern.ch/record/1122737/files/CERN-AB-2008-014.pdf;
Imported from Invenio.
Aumon, S
Gilardoni, S
Martini, M
Study of Beam Losses at Transition Crossing at the CERN PS
A series of studies has been carried out to understand and alleviate the beam losses in the CERN PS Proton Synchrotron. Losses appear especially at transition crossing during the pulsing of special quadrupoles used to create a gamma jump scheme. However, this causes a large optics and orbit distortion. After a brief summary of the gamma jump scheme at the PS, experimental and simulation results of the loss and reduction studies are presented.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc048.pdf;
http://cds.cern.ch/record/1122738/files/CERN-AB-2008-015.pdf;
Imported from Invenio.
Tomás, R
Braun, H H
Jørgensen, M
Schulte, D
Optimizing the CLIC Beam Delivery System
The optimization of the new CLIC Final Focus System (FFS) with L*=3.5m is presented for a collection of CLIC beam parameters. The final performance is computed for the full Beam Delivery System including the new diagnostics section. A comparison to previous designs is also presented.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp038.pdf;
http://cds.cern.ch/record/1122745/files/CERN-AB-2008-016.pdf;
Imported from Invenio.
Latina, A
Adli, E
Burkhardt, H
Renier, Y
Rumolo, G
Schulte, D
Tomás, R
Recent Improvements in the Tracking Code Placet
The tracking code Placet has recently undergone several improvements. A redesign of its internal data structures and a new user interface based on the mathematical toolbox Octave considerably expanded its simulation capabilities. Several new lattice elements, optimization algorithms and physics processes were added to allow for more complete start-to-end simulations. Finally, the use of the AML language and the Universal Parser Library have extended its interfacing capability. A review of these new features is presented in this paper.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupp094.pdf;
http://cds.cern.ch/record/1122948/files/CERN-AB-2008-017.pdf;
Imported from Invenio.
Salvant, B
Arduini, Gianluigi
Calaga, R
Jones, R
Métral, E
Papotti, G
Rumolo, G
Steinhagen, R
Tomás, R
Transverse Mode-Coupling Instability in the CERN SPS: Comparing Moses Analytical Calculations and Headtail Simulations with experiments in the SPS
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 after injection at 26 GeV/c in the CERN Super Proton Synchrotron (SPS) when the vertical chromaticity is corrected. Understanding the mechanisms underlying this instability is crucial to assess the feasibility of an anticipated upgrade of the SPS, which requires bunches of 4e11 protons. Analytical calculations from MOSES and macroparticle tracking simulations using HEADTAIL with an SPS transverse impedance modelled as a broadband resonator had already qualitatively and quantitatively agreed in predicting the intensity threshold of a fast instability. A sensitive frequency analysis of the HEADTAIL simulations output was performed using SUSSIX, and revealed the fine structure of the mode spectrum of the bunch coherent motion. A coupling between the azimuthal modes "-2"and "-3" was clearly observed to be the reason for this fast instability. The aim of this contribution is to compare the HEADTAIL simulations with dedicated measurements performed in the SPS in 2007.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupp067.pdf;
http://cds.cern.ch/record/1122949/files/CERN-AB-2008-018.pdf;
Imported from Invenio.
Rumolo, G
Arduini, Gianluigi
Benedetto, E
Calaga, R
Métral, E
Papotti, G
Salvant, B
Shaposhnikova, E
Experimental Study of the Electron Cloud Instability at the CERN SPS
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 decreases with increasing beam energy, if the 6D emittance of the bunch is kept constant and the longitudinal matching to the bucket is preserved. Experiments have been carried out at the CERN-SPS to study the dependence of the vertical electron cloud instability on the energy and on the beam size. The reduction of the physical transverse emittance as a function of energy is considered in fact to be the main reason for the unusual dependence of this instability on energy.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupp065.pdf;
http://cds.cern.ch/record/1122950/files/CERN-AB-2008-019.pdf;
Imported from Invenio.
Franchi, A
Gilardoni, S
Giovannozzi, M
Adiabaticity and Reversibility Studies for Beam Splitting using Stable Resonances
At the CERN Proton Synchrotron, a series of beam experiments proved beam splitting by crossing the one-fourth resonance. Depending on the speed at which the horizontal resonance is crossed, the splitting process is more or less adiabatic, and a different fraction of the initial beam is trapped in the islands. Experiments prove that when the trapping process is reversed and the islands merged together, the final distribution features thick tails. The beam population in such tails is correlated to the speed of the resonance crossing and to the fraction of the beam trapped in the stable islands. Experiments and possible theoretical explanations are discussed.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc051.pdf;
http://cds.cern.ch/record/1122951/files/CERN-AB-2008-020.pdf;
Imported from Invenio.
Barranco, J
Gilardoni, S
Study of losses during Continuous Transfer Extraction at CERN Proton Synchrotron
The proton beams used for the fixed target physics at the SPS are extracted from the PS at 14 GeV/c in five turns, using a technique called Continuous Transfer (CT). During this extraction, large losses are observed in straight sections were the machine aperture should be large enough to accommodate the circulating beam without any loss. These losses are due to particles scattered by the electrostatic septum used to slice the beam and defocused by a quadrupole used during the extraction. Simulations and experimental results are presented.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc047.pdf;
http://cds.cern.ch/record/1122952/files/CERN-AB-2008-021.pdf;
Imported from Invenio.
Jeanneret, J B
Adli, E
Latina, A
Rumolo, G
Schulte, D
Tomás, R
Beam Dynamics Issues in the CLIC Long Transfer Line
Both the main and the drive beam of the CLIC project must be transported from the central production site to the head of the main linacs over more than twenty kilometers. Over such distances chromatic error may be substantial. With long distances and large beam currents, ion-induced detuning and instabilities and multi-bunch resistive wall effects must also be considered. These effects are quantified and simulated. Based on these results, a baseline design has been established.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc018.pdf;
http://cds.cern.ch/record/1122953/files/CERN-AB-2008-022.pdf;
Imported from Invenio.
Antoniou, F
Papaphilippou, Y
Optics Design Considerations for the CLIC Pre-Damping Rings
The CLIC pre-damping rings have to accommodate a large emittance beam, coming in particular from the positron source and reduce its size to low enough values for injection into the main damping rings. Linear lattice design options based on an analytical approach for theoretical minimum emittance cells are presented. In particular the parameterisation of the quadrupole strengths and optics functions with respect to the emittance and drift lengths is derived. Complementary considerations regarding constraints imposed by positron stacking and input momentum spread are also considered.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp062.pdf;
http://cds.cern.ch/record/1122954/files/CERN-AB-2008-023.pdf;
Imported from Invenio.
Papaphilippou, Y
Braun, H H
Korostelev, M
Parameter Scan for the CLIC Damping Rings
Triggered by the RF frequency reduction of the CLIC main linac cavities, the damping ring parameters had to be reevaluated and the rings performance adapted to the new luminosity requirements. In view of a staged approach for reaching the ultimate energy of the collider, the dependence of the rings output emittances under the influence of Intrabeam Scattering is evaluated with respect to different beam characteristics such as bunch population, beam energy, coupling and longitudinal beam characteristics.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp060.pdf;
http://cds.cern.ch/record/1122955/files/CERN-AB-2008-024.pdf;
Imported from Invenio.
Rumolo, G
Bruns, W
Papaphilippou, Y
Electron Cloud Build Up and Instability in the CLIC Damping Rings
Electron cloud can be formed in the CLIC positron damping ring and cause intolerable tune shift and beam instability. Build up simulations with the Faktor2 code, developed at CERN, have been done to predict the cloud formation in the arcs and wigglers of the damping rings. HEADTAIL simulations have been used to study the effect of this electron cloud on the beam and assess the thresholds above which the electron cloud instability would set in.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp050.pdf;
http://cds.cern.ch/record/1122956/files/CERN-AB-2008-025.pdf;
Imported from Invenio.
Rumolo, G
Jeanneret, J B
Papaphilippou, Y
Quatraro, D
Collective Effects in the CLIC Damping Rings
Possible performance limitations coming fromcollective effects in the CLIC damping rings are the subject of this paper. In particular, the consequences of space charge, due to the very high beam brilliance, and of the resistive wall impedance, due to the locally very small beam pipe, are considered potentially dangerous in spite of the high beam energy. Space charge has been studied in detail with the HEADTAIL code, which was modified in order to take into account a finer lattice structure. This study also includes requirements on the broad band impedance of the damping rings and ion effects in the electron ring (electron cloud in the positron ring is treated in a companion paper). Its goal is to identify all the potential design constraints determined by these phenomena.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp049.pdf;
http://cds.cern.ch/record/1122957/files/CERN-AB-2008-026.pdf;
Imported from Invenio.
Rumolo, G
Schulte, D
Fast Ion Instability in the CLIC Transfer Line and Main LINAC
The Fast Ion Instability is believed to be a serious danger for bunch trains propagating in the CLIC electron transfer line and main linac, since it may strongly affect the bunches in the tail of the train if the vacuum pressure is not below a certain threshold. We have developed the FASTION code, which can track electrons through a FODO cell line and takes into account their interactions with the produced (and possibly trapped) ions. We describe how this tool can be used for setting tolerances on the vacuum pressure and for giving specifications for the design of a feedback system.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp048.pdf;
http://cds.cern.ch/record/1122958/files/CERN-AB-2008-027.pdf;
Imported from Invenio.
Corsini, R
Alesini, D
Biscari, C
Ghigo, A
Schulte, D
Skowronski, P K
Tecker, F
Fast Vertical Beam Instability in the CTF3 Combiner Ring
The CLIC Test Facility CTF3 is being built at CERN by an international collaboration, in order to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. The facility includes an 84 m combiner ring, which was installed and put into operation in 2007. High-current operation has shown a vertical beam break-up instability, leading to high beam losses over the four turns required for nominal operation of the CTF3 ring. Such instability is most likely due to the vertically polarized transverse mode in the RF deflectors used for beam injection and combination. In this paper we report the experimental data and compare them with simulations. Possible methods to eliminate the instability are also outlined.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp011.pdf;
http://cds.cern.ch/record/1122959/files/CERN-AB-2008-028.pdf;
Imported from Invenio.
Corsini, R
Bettoni, S
Biscari, C
Chao, Y
Döbert, S
Ghigo, A
Tecker, F
Skowronski, P
Experimental Studies on Drive Beam Generation in CTF3
The objective of the CLIC Test Facility CTF3, built at CERN by an international collaboration, is to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. CTF3 consists of a 150 MeV electron linac followed by a 42 m long delay loop, an 84 m combiner ring and a two-beam test area. One keyissue studied in CTF3 is the efficient generation of a very high current drive beam, used in CLIC as the power source for the acceleration of the main beam to multi-TeV energies. The beam current is first doubled in the delay loop and then multiplied again by a factor four in the combiner ring by interleaving bunches using transverse deflecting RF cavities. The combiner ring and the connecting transfer line have been installed and put into operation in 2007. In this paper we give the status of the commissioning, illustrate the beam optics measurements, discuss the main issues and present the results of the combination tests.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp010.pdf;
http://cds.cern.ch/record/1123153/files/CERN-AB-2008-029.pdf;
Imported from Invenio.
Abreu, N P
Blaskiewicz, M
Brown, K
Burkhardt, H
Butler, J
Fischer, W
Harvey, M
Tepikian, S
Energy Loss of Coasting Gold Ions and Deuterons in RHIC
The total energy loss of coasting gold ion beams at two different energies and deuterons at one energy were measured at RHIC, corresponding to a gamma of 75.2, 107.4 and 108.7 respectively. We describe the experiment and observations and compare the measured total energy loss with expectations from ionization losses at the residual gas, the energy loss due to impedance and synchrotron radiation. We find that the measured energy losses are below what is expected from free space synchrotron radiation. We believe that this shows evidence for suppression of synchrotron radiation which is cut off at long wavelength by the presence of the conducting beam pipe.
eng
2008
https://accelconf.web.cern.ch/e08/papers/wepp001.pdf;
http://cds.cern.ch/record/1123673/files/CERN-AB-2008-031.pdf;
Imported from Invenio.
Benedetto, E
Agapov, I
Follin, F
Kain, V
Fitting Algorithms for Optical and Beam Parameters in Transfer Lines with Application to the LHC Injection Line T12
As part of the commissioning with beam of the transfer line TI2 and TI8 from the SPS to the LHC [1], a series of optics measurements has been conducted. The paper presents the results in terms of Twiss parameters (including the dispersion), emittance and momentum spread obtained from the combination of trajectory and beam profile measurements. Profiting from the redundancy of monitors, there is a possibility of applying different fitting algorithms to retrieve beam parameters and to extract information on the optics of the line. The results from the different fit methods applied to the data will be compared with the expected values and cross-checked with independent measurements.
eng
2008
https://accelconf.web.cern.ch/e08/papers/wepp057.pdf;
http://cds.cern.ch/record/1123674/files/CERN-AB-2008-032.pdf;
Imported from Invenio.
Benedetto, E
Arduini, Gianluigi
Guerrero, A
Jacquet, D
Optics Measurements and Matching of TT2-TT10 Line for Injection of the LHC Beam in the SPS
A well matched injection in the SPS is very important for preserving the emittance of the LHC beam. The paper presents the algorithms used for the analysis and the results of the optics measurements done in the transfer line TT2-TT10 and in the SPS. The dispersion is computed by varying the beam momentum and recording the offsets at the BPMs, while the Twiss parameters and emittance measurements in TT2-TT10 are performed with beam profile monitors equipped with OTR screens. These results are completed by those obtained with a matching monitor installed in the SPS as a prototype for the LHC. This device makes use of an OTR screen and a fast acquisition system, to get the turn by turn beam profiles right at injection in the ring, from which the beam mismatch is computed and compared with the results obtained in the line. Finally, on the basis of such measurements, a betatron and dispersion matching of TT2-TT10 for injection in the SPS has been performed and successfully put in operation.
eng
2008
https://accelconf.web.cern.ch/e08/papers/wepp058.pdf;
http://cds.cern.ch/record/1123675/files/CERN-AB-2008-033.pdf;
Imported from Invenio.
Goddard, B
Bartmann, W
Benedikt, M
Kramer, T
Koschik, A
4 GeV H- Charge Exchange Injection into the PS2
The proposed PS2 will accelerate protons from 4 to 50 GeV. The required beam intensity and brightness can only be achieved with a multi-turn H- charge exchange injection system, where the small emittance injected beam is used to paint the transverse phase space of the PS2 machine. This paper describes the constraints and conceptual design of the H- injection system and its incorporation into the present PS2 lattice. The requirements for the special injection system elements are described, in particular the injection chicane and painting magnet systems and the change exchange foil. Some key performance aspects are investigated, including the stripping efficiency, expected emittance growth and beam loss arising from the simulated number of multiple foil traversals, together with estimates of foil heating.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpp087.pdf;
http://cds.cern.ch/record/1123688/files/CERN-AB-2008-034.pdf;
Imported from Invenio.
Kramer, T
Benedikt, M
Goddard, B
Vincke, H
Design Considerations for the PS2 Beam Dumps
The different beam dump functionalities required for the proposed PS2 machine and its transfer lines are briefly described, followed by first estimates about the expected beam loads. This data has been taken as input for comparing the different technical options for the dump systems, in particular to simulate the radiological impact for internal or external beam dump options. The numbers derived have been used to help decide which of the feasible technical alternatives are preferred.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpp088.pdf;
http://cds.cern.ch/record/1123689/files/CERN-AB-2008-035.pdf;
Imported from Invenio.
Borburgh, J
Balhan, B
Fowler, T
Hourican, M
Weterings, W
Septa and Distributor Developments for H- Injection into the Booster from LINAC4
The construction of Linac4 requires the modification of the existing injection system of the CERN PS Booster. A new transfer line will transport 160 MeV H- ions to this machine. A system of 5 pulsed magnets (BIDIS) and 3 vertical septa (BISMV) will distribute and inject the Linac pulses into the four-vertically separated Booster rings. Subsequently the beam will be injected horizontally, using a local bump created with bumpers (BS magnets) to bring the injected H- beam together with the orbiting proton beam onto the stripper foil. To accommodate the injected H- beam, the first of the BS magnets will have to be a septum-like device, deflecting only the orbiting beam. This paper highlights the requirements and technical issues and describes the solutions to be adopted for both the BIDIS and BISMV. The results of initial prototype testing of the BIDIS magnet will also be presented.
eng
2008
https://accelconf.web.cern.ch/e08/papers/wepc141.pdf;
http://cds.cern.ch/record/1123691/files/CERN-AB-2008-036.pdf;
Imported from Invenio.
Bartmann, W
Benedikt, M
Métral, E
Möhl, D
Peggs, S
Gamma Transition Jump for PS2
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 maximum energy of 50 GeV. One of the possible lattices (FODO option) foresees crossing of transition energy near 10 GeV. Since the phase-slip-factor $\eta$ becomes very small near transition energy, many intensity dependent effects can take place in both longitudinal and transverse planes. The aim of the present paper is on the one hand to scale the gamma transition jump, used since 1973 in the PS, to the projected PS2 and on the other hand based on these results the analysis of the implementation and feasibility of a gamma transition jump scheme in a conventional FODO lattice.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpp089.pdf;
http://cds.cern.ch/record/1123717/files/CERN-AB-2008-037.pdf;
Imported from Invenio.
Wenninger, J
Protection Controls for High Power Accelerators
The next generation hadron accelerators will operate with MW beams or store beams with an energy of many 100 MJ. Such accelerators must be protected by fast and very reliable interlock systems to avoid damage due to uncontrolled beam loss. Machine protection will constrain operation, but some operational flexibility is still required for commissioning and performance optimization. This is a substantial challenge for control systems and application programs. New tools are developed to face those challenges: critical settings management, software interlocks, role based access to equipment, automatic accelerator mode recognition etc. This talk presents some of the challenges and tools. Experience with novel approaches are discussed.
eng
2008
https://accelconf.web.cern.ch/e08/papers/wezg01.pdf;
http://cds.cern.ch/record/1123722/files/CERN-AB-2008-038.pdf;
Imported from Invenio.
Gilardoni, S
Franchi, A
Giovannozzi, M
Progress in the Beam preparation for the Multi-Turn Extraction at the CERN Proton Synchrotron
A new type of extraction based on beam trapping inside stable islands in the horizontal phase space will become operational during 2008 at the CERN Proton Synchrotron. A series of beam experiments was carried out to prove lossless capture with high intensity and multi-bunched beams, up to $1.5 × 10^{13}$ protons per pulse, in preparation of the extraction commissioning. These fundamental steps for the new Multi-turn Extraction are presented and discussed in details.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc049.pdf;
http://cds.cern.ch/record/1123725/files/CERN-AB-2008-039.pdf;
Imported from Invenio.
Gilardoni, S
Franchi, A
Giovannozzi, M
Experimental Evidence of Beam Trapping with one-third and one-fifth Resonance Crossing
Beam trapping in stable islands of the horizontal phase space generated by non-linear magnetic fields is realized by means of a given tune variation so to cross a resonance of order n. Whenever the resonance is stable, n + 1 beamlets are created whereas if the resonance is unstable, the beam is split in n parts. Experiments at the CERN Proton Synchrotron showed protons trapped in stable islands while crossing the one-third and one-fifth resonance with the creation of 3 and 6 stable beamlets, respectively. The results are presented and discussed.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thpc050.pdf;
http://cds.cern.ch/record/1123728/files/CERN-AB-2008-040.pdf;
Imported from Invenio.
Willeke, F
Bordry, Frederick
Braun, H H
Brüning, Oliver Sim
Burkhardt, H
Chattopadhyay, S
Dainton, J B
Holzer, B
Jowett, John M
Klein, M
Linnecar, T
Mess, K H
Myers, S
Osborne, J
Zimmermann, F
A Storage Ring based Option for the LHeC
The LHeC aims at the generation of hadron-lepton collisions with center of mass energies in the TeV scale and luminosities of the order of $10^{32}-10^{33} cm^{-2} sec^{-1}$ by taking advantage of the existing LHC 7 TeV proton ring and adding a high energy electron accelerator. This paper presents technical considerations and potential parameter choices for such a machine and outlines some of the challenges arising when an electron storage ring based option, constructed within the existing infrastructure of the LHC, is chosen.
eng
2008
https://accelconf.web.cern.ch/e08/papers/wepp052.pdf;
http://cds.cern.ch/record/1124065/files/CERN-AB-2008-041.pdf;
Imported from Invenio.
Riddone, G
Mainaud-Durand, H
Nousiainen, R
Samoshkin, A
Schulte, D
Syratchev, I
Wuensch, W
Zennaro, R
Technical Specification for the CLIC Two-Beam Module
A high-energy (0.5-3 TeV centre-of-mass), highluminosity Compact Linear Collider (CLIC) is being studied at CERN [1]. The CLIC main linacs, 21-km long each, are composed of 2-m long two beam modules. This paper presents their current layout, the main requirements for the different sub-systems (alignment, supporting, stabilization, cooling and vacuum) as well as the status of their integration.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp028.pdf;
http://cds.cern.ch/record/1124077/files/CERN-AB-2008-042.pdf;
Imported from Invenio.
Zennaro, R
Study of the Validity of K. Bane's Formulae for the CLIC Accelerator Structure
The comprehension of short range wakefields is essential for the design of CLIC. Useful tools are the Karl Bane's formulae which provide geometrical parameterization of the short range wake for periodic rotational-symmetric structures. The comparison of 2D computations based on ABCI with predicted results and the study of the range of validity of these formulae are the subjects of this paper. An extended model for rounded iris structures is also proposed.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp045.pdf;
http://cds.cern.ch/record/1124081/files/CERN-AB-2008-043.pdf;
Imported from Invenio.
Kovermann, J W
Calatroni, S
Descoeudres, A
Lefèvre, T
Wuensch, W
Advanced Experimental Techniques for RF and DC Breakdown Research
Advanced experimental techniques are being developed to analyze RF and DC breakdown events. First measurements with a specially built spectrometer have been made with a DC spark setup [1] at CERN and will soon be installed in the CLIC 30GHz accelerating structure test stand to allow comparison between DC and RF breakdown phenomena. This spectrometer is able to measure the light intensity development during a breakdown in narrow wavelength bands in the visible and near infrared range. This will give information about the important aspects of the breakdown including chemical elements, temperature, plasma parameters and possibly precursors of a breakdown.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopp095.pdf;
http://cds.cern.ch/record/1124085/files/CERN-AB-2008-044.pdf;
Imported from Invenio.
Wuensch, W
CLIC Accelerating Structure Development
One of the most important objectives of the CLIC (Compact Linear Collider) study is to demonstrate the design accelerating gradient of 100 MV/m in a fully featured accelerating structure under nominal operating conditions including pulse length and breakdown rate. The main issues which must be addressed and their interrelations are described along with the development and testing programs which have been put into place to accomplish this feasibility demonstration.
eng
2008
https://accelconf.web.cern.ch/e08/papers/thxm01.pdf;
http://cds.cern.ch/record/1124103/files/CERN-AB-2008-045.pdf;
Imported from Invenio.
Tückmantel, Joachim
Digital Generation of Noise-Signals with Arbitrary Constant or Time-Varying Spectra
Noise sources in the RF system of an accelerator produce longitudinal emittance increase or particle loss. This noise is inherent, from the beam-control system electronics, external sources or high power components, or can be purposely injected for a specific need such as bunch distribution modification or controlled emittance increase. Simulations to study these effects on the beam require precise reproduction either of the total noise measured on the hardware, or of the noise spectrum to be injected and optimized to produce the desired changes. In the latter case the 'optimized' noise source has also to be created in real-time to actually excite the beam via the RF system. This paper describes a new algorithm to create noise spectra of arbitrary spectral density varying with cycle time. It has very good statistical properties and effectively infinite period length, important for long simulation runs. It is spectrally clean and avoids undesired mirror spectra. Coded in C++, it is flexible and fast. Used extensively in simulations it has also successfully created controlled emittance increase in the SPS by the injection of artificial real-time RF noise.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupc103.pdf;
http://cds.cern.ch/record/1124106/files/CERN-AB-2008-047.pdf;
Imported from Invenio.
Angoletta, M E
Bourrion, O
De Martinis, C
Falbo, L
Findlay, A
Foglio, R
Hunt, S
Tourres, D
Vescovi, C
CERN PSB Beam Tests of CNAO Synchrotron's Digital LLRF
The Italian National Centre for Oncological hAdrontherapy (CNAO), in its final construction phase, uses proton and carbon ion beams to treat patients affected by solid tumours. At the heart of CNAO is a 78- meter circumference synchrotron that accelerates particles to up to 400 MeV/u. The synchrotron relies on a digital LLRF system based upon Digital Signal Processors (DSPs) and Field Programmable Gate Array (FPGA). This system implements cavity servoing and beam control capabilities, such as phase and radial loops. Beam tests of the CNAO synchrotron LLRF system were carried out at CERN's Proton Synchrotron Booster (PSB) in autumn 2007, to verify the combined DSP/FPGA architecture and the beam control capabilities. For this, a prototype version of CNAO's LLRF system was adapted to the PSB requirements. This paper outlines the prototype system layout and describes the tests carried out and their results. In particular, system architecture and beam control capabilities were successfully proven by comparison with the PSB operational beam control system and with the help of several existing beam diagnostic systems.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupc154.pdf;
http://cds.cern.ch/record/1124107/files/CERN-AB-2008-048.pdf;
Imported from Invenio.
Deile, Mario
Caspers, Fritz
Kroyer, Tom
Oriunno, Marco
Radermacher, Ernst
Soter, Anna
Roncarolo, Federico
Beam Coupling Impedance Measurement and Mitigation for a TOTEM Roman Pot
Conf. Proc. C
TUPP029
0806233
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 the wire position has been kept constant, and the insertions of the RP were moved asymmetrically. With the original configuration of the RP, resonances with fairly high Q values were observed. In order to mitigate this problem, RF-absorbing ferrite plates were mounted in appropriate locations. As a result, all resonances were sufficiently damped to meet the stringent LHC beam coupling impedance requirements.
eng
2008
http://accelconf.web.cern.ch/e08/papers/tupp029.pdf;
http://cds.cern.ch/record/1124108/files/arXiv:0806.4974.pdf;
http://cds.cern.ch/record/1124108/files/TUPP029f04.png;
http://cds.cern.ch/record/1124108/files/TUPP029f05.png;
http://cds.cern.ch/record/1124108/files/TUPP029f07.png;
http://cds.cern.ch/record/1124108/files/TUPP029f01b.png;
http://cds.cern.ch/record/1124108/files/TUPP029f02.png;
http://cds.cern.ch/record/1124108/files/TUPP029f01a.png;
http://cds.cern.ch/record/1124108/files/TUPP029f08.png;
http://cds.cern.ch/record/1124108/files/TUPP029f03a.png;
http://cds.cern.ch/record/1124108/files/TUPP029f03b.png;
http://cds.cern.ch/record/1124108/files/TUPP029f06c.png;
http://cds.cern.ch/record/1124108/files/TUPP029f06b.png;
http://cds.cern.ch/record/1124108/files/TUPP029f06a.png;
http://cds.cern.ch/record/1124108/files/CERN-AB-2008-049.pdf;
Imported from Invenio.
Damerau, H
Hancock, S
Kroyer, T
Mahner, E
Schokker, M
Electron Cloud Mitigation by Fast Bunch Compression in the CERN PS
A fast transverse instability has been observed with nominal LHC beams in the CERN Proton Synchrotron (PS) in 2006. The instability develops within less than 1 ms, starting when the bunch length decreases below a threshold of 11.5 ns during the RF procedure to shorten the bunches immediately prior to extraction. An alternative longitudinal beam manipulation, double bunch rotation, has been proposed to compress the bunches from 14 ns to the 4 ns required at extraction within 0.9 ms, saving some 4.5 ms with respect to the present compression scheme. The resultant bunch length is found to be equivalent for both schemes. In addition, electron cloud and vacuum measurements confirm that the development of an electron cloud and the onset of an associated fast pressure rise are delayed with the new compression scheme. Beam dynamics simulations and measurements of the double bunch rotation are presented as well as evidence for its beneficial effect from the electron cloud standpoint.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupp050.pdf;
http://cds.cern.ch/record/1124109/files/CERN-AB-2008-050.pdf;
Imported from Invenio.
Syratchev, I
Riddone, G
Tantawi, S
CLIC RF High Power Production Testing Program
The CLIC Power Extraction and Transfer Structure (PETS) is a passive microwave device in which bunches of the drive beam interact with the impedance of the periodically loaded waveguide and generate RF power for the main linac accelerating structure. The demands on the high power production (~ 150 MW) and the needs to transport the 100 A drive beam for about 1 km without losses, makes the PETS design rather unique and the operation very challenging. In the coming year, an intense PETS testing program will be implemented. The target is to demonstrate the full performance of the PETS operation. The testing program overview and test results available to date are presented.
eng
2008
https://accelconf.web.cern.ch/e08/papers/weobg01.pdf;
http://cds.cern.ch/record/1124110/files/CERN-AB-2008-051.pdf;
Imported from Invenio.
The MERIT(nTOF-11) experiment is a proof-ofprinciple test of a target system for a high power proton beam to be used as front-end for a neutrino factory or a muon collider. The experiment took data in autumn 2007 with the fast-extracted beam from the CERN Proton Synchrotron (PS) to a maximum intensity of $30 × 10^{12}$ per pulse. The target system, based on a free mercury jet, is capable of intercepting a 4-MW proton beam inside a 15-T magnetic field required to capture the low energy secondary pions as the source for intense muon beams. Partice detectors installed around the target setup measure the secondary particle flux out of the target and can probe cavitation effects in the mercury jet when excited by an intense proton beam.Preliminary results of the data analysis will be presented here.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopc087.pdf;
http://cds.cern.ch/record/1124302/files/CERN-AB-2008-053.pdf;
Imported from Invenio.
Holzer, E B
Chiggiato, P
Dehning, B
Ferioli, G
Grishin, V
Jimenez, T M
Koshelev, A
Kramer, Daniel
Larionov, A
Taborelli, M
Seleznev, V
Sleptsov, M
Sytin, A
Wevers, I
Development, Production and Testing of 4500 Beam Loss Monitors
Beam-loss monitoring (BLM) [1] is a key element in the LHC machine protection. 4250 nitrogen filled ionization chambers (IC) and 350 secondary emission monitors (SEM) have been manufactured and tested at the Institute for High Energy Physics (IHEP) in Protvino, Russia, following their development at CERN. Signal speed and robustness against aging were the main design criteria. Each monitor is permanently sealed inside a stainless-steel cylinder. The quality of the welding was a critical aspect during production. The SEMs are requested to hold a vacuum of $10^{-7}$ bar. Impurity levels from thermal and radiationinduced desorption should remain in the range of parts per million in the ICs. To avoid radiation aging (up to $2·10^{8}$ Gy in 20 years) production of the chambers followed strict UHV requirements. IHEP designed and built the UHV production stand. Due to the required dynamic range of $10^{8}$, the leakage current of the monitors has to stay below 2 pA. Several tests during and after production were performed at IHEP and CERN. A consistently high quality during the whole production period was achieved and the tight production schedule kept at the same time.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupc037.pdf;
http://cds.cern.ch/record/1124309/files/CERN-AB-2008-054.pdf;
Imported from Invenio.
D'Elia, A
Fandos, R
Søby, L
High Bandwidth Wall Current Monitor for CTF3
Wall Current Monitors (WCM) are commonly used to observe the time profile and spectra of a particle beam by detecting its image current. Within the framework of the EUROTeV Programme, a WCM for CLIC and ILC having a very large bandwidth (100kHz-20GHz) is required and has been developed. A deep study of the field configuration for the device has been necessary. Consequently, the geometrical parameters crucial for a proper functioning of the structure have been found. Furthermore, the very stringent initial requests (bandwidth from 100kHz to 20GHz) were reviewed in a more critical way showing that the low frequency cutoff can be sensibly increased, thus avoiding any ferrite in the structure.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupc021.pdf;
http://cds.cern.ch/record/1124312/files/CERN-AB-2008-055.pdf;
Imported from Invenio.
Barnes, M
Balhan, B
Borburgh, J
Fowler, T
Goddard, B
Ueda, A
Weterings, W
Development of an Eddy Current Septum for LINAC4
A linear accelerator (linac) is the first stage of the CERN accelerator complex. The linac defines the beam quality for subsequent stages of acceleration and the reliability has to be high as a fault of the linac shuts down all other machines. The existing linacs at CERN were designed 30 or more years ago: recent upgrades allowed the linacs to reach LHC requirements but also showed that they are at the limit of their brightness and intensity capabilities. A replacement Superconducting Proton Linac (SPL) has been proposed; the initial part of the SPL is termed LINAC4. The LINAC4 injection bump would be made up of a set of four pulsed dipole magnets; the first of these magnets (BS1) must act as a septum with a thin element dividing the high-field region of the circulating beam from the field-free region through which injected $H^{-}$ beam must pass. The initial specifications for BS1 required; a deflection of 66 mrad at 160 MeV, achieved with a peak field of 628 mT and a length of 250 mm: the field fall time was $40 \mu$s with a flattop of at least $100 \mu$s. The ripple of the flattop should be below ±1%. This paper discusses the design of an eddy current septum for BS1.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupd002.pdf;
http://cds.cern.ch/record/1124314/files/CERN-AB-2008-056.pdf;
Imported from Invenio.
Barnes, M
Ducimetière, L
Goddard, B
Uythoven, J
Upgrading the Fast Extractions Kicker System in SPS LSS6
A fast extraction system, located in the LSS6 region of the CERN SPS accelerator, transfers 450 GeV/c protons, as well as ions, via the TI 2 transfer line towards the LHC. The system includes three travelling wave kicker magnets, all powered in series, energised by a single Pulse Forming Network (PFN) and terminated by a short circuit. The specification for the system requires a kick flattop of $7.8 \mu$s with a ripple of not more than ±0.5%. Recent measurements with beam show that the ±0.5% kick specification is achieved over $7.1 \mu$s of the kick flattop; however the ripple over $7.8 \mu$s is ±0.75%. Initial electrical measurements have been carried out on each of the three magnets; more detailed comparisons of the beam measurements and the contribution of each magnet to the detailed shape of the flattop kick will be carried out. This paper reports the results of initial measurements and plans for future measurements to permit modifications to the PFN for reducing flattop ripple.
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupd003.pdf;
http://cds.cern.ch/record/1124315/files/CERN-AB-2008-057.pdf;
Imported from Invenio.
Manglunki, Django
Albert, M
Angoletta, M E
Arduini, Gianluigi
Baudrenghien, P
Bellodi, G
Belochitskii, P
Benedetto, E
Bohl, T
Carli, C
Carlier, E
Chanel, M
Damerau, H
Gilardoni, S
Hancock, S
Jacquet, D
Jowett, John M
Kain, V
Küchler, D
Martini, M
Maury, S
Métral, E
Normann, L
Papotti, G
Pasinelli, S
Schokker, M
Scrivens, R
Tranquille, G
Vallet, J L
Vandorpe, B
Wehrle, U
Wenninger, J
Ions for LHC: Towards Completion of the Injector Chain
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 2006 [3], the Super Proton Synchrotron (SPS) has now been commissioned with the 'Early' ion beam, which should give a luminosity of $5×10^{25}cm^{-2}s^{-1}$ in the LHC. This paper summarizes the operation in 2007 of all the machines involved in the ion injection chain.
eng
2008
https://accelconf.web.cern.ch/e08/papers/mopc131.pdf;
http://cds.cern.ch/record/1124319/files/CERN-AB-2008-058.pdf;
Imported from Invenio.
Dubrovskiy, A
Rodríguez, José Alberto
An Automatic Control System for Conditioning 30 GHz Accelerating Structures
A software application programme has been developed to allow fast and automatic high-gradient conditioning of accelerating structures at 30 GHz in CTF3. The specificity of the application is the ability to control the high-power electron beam which produces the 30 GHz RF power used to condition the accelerating structures. The programme permits operation round the clock with minimum manpower requirements. In this paper the fast control system, machine control system, logging system, graphical user control interface and logging data visualization are described. An outline of the conditioning control system itself and of the feedback controlling peak power and pulse length is given. The software allows different types of conditioning strategies to be programmed
eng
2008
https://accelconf.web.cern.ch/e08/papers/tupp008.pdf;
http://cds.cern.ch/record/1125173/files/CERN-AB-2008-059.pdf;
Imported from Invenio.