Keyword: luminosity
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MOYAA01 The LHC from Commissioning to Operation injection, controls, optics, ion 11
 
  • M. Lamont
    CERN, Geneva, Switzerland
  
  In 2011 the LHC moves from commissioning into the physics production phase with the aim of accumulating 1fb-1 by the end of 2011. The progress from commissioning to operation is described. Emphasis is put on the beam performance, but also on the performance of the different hardware systems. The role of collimation and machine protection is discussed, in view of the very high stored beam and magnet energy. Comment: Other invited presentations in this conference will cover the experience with beam instrumentation and the upgrade programmes.  
slides icon Slides MOYAA01 [7.410 MB]  
 
MOPC106 Study of the Variation of Transverse Voltage in the 4 Rod Crab Cavity for LHC cavity, simulation, HOM, dipole 322
 
  • B.D.S. Hall, P.K. Ambattu, G. Burt, C. Lingwood
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P. Goudket, C. Hill
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  The planned high luminosity upgrade to LHC will utilise crab cavities to rotate the beam in order to increase the luminosity in the presence of a finite crossing angle. A compact design is required in order for the cavities to fit between opposing beam-lines. In this paper we discuss we discuss one option for the LHC crab cavity based on a 4 rod TEM deflecting cavity. Due to the large transverse size of the LHC beam the cavity is required to have a large aperture while maintaining a constant transverse voltage across the aperture. The cavity has been optimised to minimise the variation of the transverse voltage while keeping the peak surface electric and magnetic fields low for a given kick. This is achieved while fitting within the strict design space of the LHC. The variation of deflecting voltage across the aperture has been studied numerically and compared with numerical and analytical estimates of other deflecting cavity types. Performance measurements an aluminium prototype of this cavity are presented and compared to the simulated design.  
 
MOPC120 Design of Superconducting Parallel-bar Deflecting/Crabbing Cavities cavity, coupling, SRF, proton 361
 
  • J.R. Delayen, S.U. De Silva
    ODU, Norfolk, Virginia, USA
  
  The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. We present an analysis of several designs of parallel-bar cavities and their electromagnetic properties.  
 
MOPO006 DAΦNE Bunch-by-bunch Feedback Upgrade as SuperB Design Test feedback, diagnostics, factory, controls 490
 
  • A. Drago
    INFN/LNF, Frascati (Roma), Italy
  • D. Teytelman
    Dimtel, San Jose, USA
  
  DAΦNE, the PHI-factory located in Frascati, has always shown dynamic behavior strongly dependent on the bunch-by-bunch feedback, since its first runs in 1997. Over the years, to keep up with the evolving machine requirements, transverse and longitudinal systems have received multiple upgrades and updates. During fall 2010, all the six DAΦNE feedback systems have been upgraded to support the next run for KLOE as well as to test bunch-by-bunch feedback architectures intended for the future Italian SuperB factory. Both e+/e- longitudinal feedback systems have been completely replaced with new hardware for increased reliability, better diagnostics and improved maintainability. In the effort to reduce residual dipole beam motion, determined by the front-end and quantization noise floor, vertical feedback systems now feature a 12-bit ADC, in place of the older 8-bit design. In the paper, we describe the hardware and software changes of this upgrade. Feedback performance analysis and beam dynamics data collected by the systems are presented.  
 
MOPO014 SVD-based Filter Design for the Trajectory Feedback of CLIC ground-motion, feedback, controls, simulation 511
 
  • J. Pfingstner, D. Schulte, J. Snuverink
    CERN, Geneva, Switzerland
  • M. Hofbaur
    UMIT, Hall in Tirol, Austria
  
  The orbit feedback of the Compact Linear Collider (CLIC) is the basic counter-measure against ground motion effects below 1 Hz in the beam delivery system and the main linac of CLIC. In this paper we present significant improvements of the orbit feedback design, by using time-dependent and spatial filters. The design procedure is based on a singular value decomposition (SVD) of the orbit response matrix and on loop-shaping techniques. This modified design has essential advantages compared to previous ones. The required beam position monitor resolution in the beam delivery system could be relaxed by a factor of five. At the same time the suppression of ground motion effects is improved. As a consequence, the tight tolerances for the allowable luminosity loss due to ground motion effects in CLIC can be met. The presented methods can be easily adapted to other accelerators in order to relax sensor tolerances and to efficiently suppress ground motion effects.  
 
MOPS003 Coherent Beam-beam Resonances in SuperB with Asymmetric Rings resonance, simulation, collider, dynamic-aperture 592
 
  • M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • Y. Zhang
    IHEP Beijing, Beijing, People's Republic of China
  
  One of the latest options of SuperB foresees exploiting rings with unequal circumferences. In such a configuration additional coherent beam-beam resonances can arise. In this paper we discuss the possible impact of the resonances on beam dynamics in SuperB, maximum achievable tune shifts and working point choice.  
 
MOPS057 Beam-beam Interaction under External Force Oscillation positron, simulation, electron, kicker 736
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  
  Beam-ion interaction is strongly nonlinear. Response for external oscillation applied to beam shows characteristic feature. Simulations for external frequency scan becomes feasible for the recent computer power. We show the frequency response for beam-ion system in KEK-PF and recent low emittance rings.  
 
MOPS069 Review of Beam Instabilities in the Presence of Electron Clouds in the LHC emittance, electron, injection, simulation 760
 
  • K.S.B. Li, G. Rumolo
    CERN, Geneva, Switzerland
  
  Recent observations at the LHC indicate the build-up of electron clouds when 50 ns spaced beams are injected into the machine at nominal intensity. These electron clouds are a source of coherent beam instabilities and incoherent emittance growth and limit the achievable luminosity. To better understand the influence of electron clouds on the beam dynamics, simulations have been carried out to study both the coherent and the incoherent effects on the beam. The simulations are performed with the HeadTail tracking code; the usage of new post-processing software allows determining not only the beam intensity thresholds in terms of the central electron cloud density but also the footprint of the beam in tune space. In this paper we review instability thresholds and tune footprints for beams with different emittances and interacting with an electron cloud in field-free or dipole regions.  
 
MOPS091 Study of Electron Cloud for MEIC electron, simulation, emittance, dipole 817
 
  • S. Ahmed, J.D. Dolph, G.A. Krafft, T. Satogata, B.C. Yunn
    JLAB, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Medium Energy Electron Ion Collider (MEIC) at Jefferson Lab has been envisioned as a future high energy particle accelerator beyond the 12 GeV upgrade of the existing Continuous Electron Beam Accelerator Facility (CEBAF). Synchrotron radiation from the closely spaced proton bunches in MEIC can generate photoelectrons inside the vacuum chamber and cause secondary emission due to multipacting in the presence of beam's electric field. This phenomenon can lead to fast build up of electron density, known as electron cloud effect – resulting into beam instability coupled to multi-bunches in addition to a single bunch. For MEIC, the estimated threshold value of the electron-cloud density is approximately 5 x 1012 m-3. In this paper, we would like to report the self-consistent simulation studies of electron cloud formation for MEIC. The code has been benchmarked against the published data of electron cloud effects observed in LHC. Our first simulations predict increase of electron clouds with the increase of repetition rate. The detailed simulations are under progress and will be reported. 		 
 
TUYA01 Achievements and Lessons from the Tevatron antiproton, collider, proton, electron 903
 
  • V.D. Shiltsev
    Fermilab, Batavia, USA
  
  The Tevatron Run-2 will come to an end at the time of IPAC'11. This talk will concentrate on exploration of the accelerator physics issues that were dealt with in achieving the current (very high) level of performance in the Tevatron and will review achievements, challenges and lessons learned on the way.  
slides icon Slides TUYA01 [5.881 MB]  
 
TUYA02 LHC Upgrade Plans: Options and Strategy cavity, quadrupole, collider, cryogenics 908
 
  • L. Rossi
    CERN, Geneva, Switzerland
  
  Presentation of options for future luminosity and/or energy upgrades of the LHC ring. The presentation should cover the different ideas, short term, medium term and long term, and discuss the research programme that is needed to prepare the upgrades.  
slides icon Slides TUYA02 [5.139 MB]  
 
TUYA03 Stochastic Cooling of a High Energy Collider simulation, kicker, pick-up, cavity 913
 
  • M. Blaskiewicz, J.M. Brennan, R.C. Lee, K. Mernick
    BNL, Upton, Long Island, New York, USA
  
  Three dimensional stochastic cooling was successfully implemented at the Relativistic Heavy Ion Collider to overcome emittance growth from intra-beam scattering. The talk reports on the experience of operating a collider with continuous cooling. The application of such techniques to other hadron machine (e.g. LHC) will be discussed.  
slides icon Slides TUYA03 [1.350 MB]  
 
TUYB03 CLIC Conceptual Design and CTF3 Results linac, emittance, target, damping 961
 
  • D. Schulte
    CERN, Geneva, Switzerland
  
  An international collaboration is carrying out an extensive R&D programme to prepare CLIC, a multi-TeV electron-positron collider. In this concept, the colliding beams will be accelerated in very high gradient normal conducting 12 GHz accelerating structures. The necessary RF power is extracted from a high-current, low-energy drive beam that runs parallel to the colliding beams and is generated in a central complex. This year the collaboration will produce a conceptual design report to establish the feasibility of the technology. The CLIC concept will be introduced and the status of key studies of critical issues will be reviewed. A focus will be on the CLIC Test Facility 3 (CTF3), which is a test facility to produce and use high current a drive beam.  
slides icon Slides TUYB03 [13.204 MB]  
 
TUPC002 Study of a Large Piwinski’s Angle Configuration for Linear Colliders collider, linear-collider, radiation, background 988
 
  • R. Versteegen, O. Napoly
    CEA/DSM/IRFU, France
  
  The application of a Large Piwinski’s Angle configuration to the interaction region of a linear collider is studied. The calculation of the equivalent disruption parameter and beamstrahlung parameter in the presence of a crossing angle are necessary to estimate the beam-beam effects in such a configuration. The reduction of the beam-beam interaction effects, based on these parameters, while keeping same luminosity is presented for both ILC and CLIC parameters.  
 
TUPC004 The Luminosity for the ILC Travelling Focus Regime with Offsets and Angle Scans* emittance, simulation, collider, wakefield 991
 
  • L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, A. Ushakov
    University of Hamburg, Hamburg, Germany
  • K. Buesser, A.F. Hartin, G.A. Moortgat-Pick, N.J. Walker
    DESY, Hamburg, Germany
  • S. Riemann, F. Staufenbiel
    DESY Zeuthen, Zeuthen, Germany
  
  One of the crucial challenges of a future linear collider is to provide high luminosity. In the current ILC design a luminosity of 2x1034 is foreseen. In order to enhance the luminosity, use of the “travelling focus” scheme is under discussion. Within this regime the hourglass effect at the interaction point can be effectively overcome by judiciously arranging for the head and tail of the bunches to be focused at a proportionally displaced longitudinal position. The effect is further enhanced by the strong beam-beam interaction which continuously focuses the bunches during collision. In principle travelling focus could provide an additional 30% luminosity. Nevertheless the regime is highly sensitive to beam-beam transverse and angular offsets at the collision point. The study of the luminosity stability for various ILC parameters using traveling focus will be presented.  
 
TUPC013 Simulation of Phase Stability at the Flat Top of the CLIC Drive Beam linac, simulation, kicker, collider 1018
 
  • A. Gerbershagen, D. Schulte
    CERN, Geneva, Switzerland
  • P. Burrows
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  
  Funding: University of Oxford
The drive beam phase stability is one of the critical issues of the Compact Linear Collider (CLIC). In this paper the generation and propagation of drive beam phase errors is studied for effects that vary during the drive beam pulse. This includes the influence of drive beam current and phase errors as well as of drive beam accelerator RF phase and amplitude errors on the drive beam phase after the compressor chicanes and the analysis of the propagation of these errors through the drive beam combination scheme. The impact of the imperfections on the main beam is studied including the possible correction with help of a feedforward system. 		 
 
TUPC014 System Control for the CLIC Main Beam Quadrupole Stabilization and Nano-positioning* feedback, quadrupole, ground-motion, simulation 1021
 
  • S.M. Janssens, K. Artoos, C.G.R.L. Collette, M. Esposito, P. Fernandez Carmona, M. Guinchard, C. Hauviller, A.M. Kuzmin, R. Leuxe, J. Pfingstner, D. Schulte, J. Snuverink
    CERN, Geneva, Switzerland
  
  The conceptual design of the active stabilization and nano-positioning of the CLIC main beam quadrupoles was validated in models and experimentally demonstrated on test benches. Although the mechanical vibrations were reduced to within the specification of 1.5 nm at 1 Hz, additional input for the stabilization system control was received from integrated luminosity simulations that included the measured stabilization transfer functions. Studies are ongoing to obtain a transfer function which is more compatible with beam based orbit feedback; it concerns the controller layout, new sensors and their combination. In addition, the gain margin must be increased in order to reach the requirements from a higher vibration background. For this purpose, the mechanical support is adapted to raise the frequency of some resonances in the system and the implementation of force sensors is considered. Furthermore, this will increase the speed of repositioning the magnets between beam pulses. This paper describes the improvements and their implementation from a controls perspective.  
 
TUPC023 Status of Ground Motion Mitigation Techniques for CLIC feedback, quadrupole, simulation, ground-motion 1048
 
  • J. Snuverink, K. Artoos, C.G.R.L. Collette, F. Duarte Ramos, A. Gaddi, H. Gerwig, S.M. Janssens, J. Pfingstner, D. Schulte
    CERN, Geneva, Switzerland
  • G. Balik, L. Brunetti, A. Jeremie
    IN2P3-LAPP, Annecy-le-Vieux, France
  • P. Burrows
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • B. Caron
    SYMME, Annecy-le-Vieux, France
  • J. Resta-López
    IFIC, Valencia, Spain
  
  The Compact Linear Collider (CLIC) accelerator has strong stability requirements on the position of the beam. In particular, the beam position will be sensitive to ground motion. A number of mitigation techniques are proposed - quadrupole stabilisation and positioning, final doublet stabilisation as well as beam based orbit and interaction point (IP) feedback. Integrated studies of the impact of the ground motion on the CLIC Main Linac (ML) and Beam Delivery System (BDS) have been performed, which model the hardware and beam performance in detail. Based on the results future improvements of the mitigation techniques are suggested and simulated. It is shown that with the current design the tight luminosity budget for ground motion effects is fulfilled and accordingly, an essential feasibility issue of CLIC has been addressed.  
 
TUPC027 CLIC Post-Collision Line Luminosity Monitoring photon, simulation, monitoring, feedback 1057
 
  • R. Appleby
    UMAN, Manchester, United Kingdom
  • A. Apyan, L.C. Deacon, E. Gschwendtner
    CERN, Geneva, Switzerland
  
  The CLIC post collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14 MW to the main beam dump. Full Monte Carlo simulation has been done for the description of the Compact Linear Collider (CLIC) luminosity monitoring at the post collision line. One method of the luminosity diagnostic is based on the detection of high energy muons produced by the beamsstrahlung photons in the main beam dump. The disrupted beam and the beamsstrahlung photons produce at the order of 106 muons per bunch crossing, with energies greater than 10 GeV. Currently threshold Cherenkov counters are considered after the beam dump for the detection of these high energy muons. A second method using the direct detection of the beamsstrahlung photons is also considered.  
 
TUPC134 Phase Detection Electronics for CLIC pick-up, controls, linac, linear-collider 1338
 
  • A. Andersson
    CERN, Geneva, Switzerland
  
  The Compact Linear Collider (CLIC) requires very tight RF phase synchronisation in order to preserve high luminosity. The electronics required for processing the signals delivered from the phase pick-ups present a significant challenge. This paper discusses the strategy adopted to achieve a sufficiently accurate measurement of the phase. Performance measurements performed in the lab of some of the sub-systems are also presented.  
 
TUPC155 Optimisation of the LHC Beam Current Transformers for Accurate Luminosity Determination instrumentation, pick-up, monitoring, synchrotron 1395
 
  • J-J. Gras, D. Belohrad, M. Ludwig, P. Odier
    CERN, Geneva, Switzerland
  • C. Barschel
    RWTH, Aachen, Germany
  
  During the 2010 and 2011 LHC runs a series of dedicated fills were used for luminosity calibration measurements at each of the LHC experiments. A major contribution to the final precision of these luminosity calibration campaigns originated from the absolute accuracy of the bunch current population estimation. The importance of these measurements for the LHC physics community triggered a large and fruitful collaboration between the CERN Beam Instrumentation Group and the LHC Experiments to push the LHC Beam Current Transformers performance to their limit. This paper will report on the available instruments for beam current measurements, the methodology used to improve them and the results obtained.  
 
TUPC168 Results from the LHC BRAN Luminosity Monitor at Increased Luminosities emittance, radiation, injection, simulation 1428
 
  • R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • E. Bravin
    CERN, Geneva, Switzerland
  • H.S. Matis, A. Ratti, W.C. Turner, H. Yaver, T. stezelberger
    LBNL, Berkeley, California, USA
  
  Funding: This work supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The LHC BRAN luminosity monitors are used to monitor and optimize the luminosity at the LHC high luminosity interaction points IP1 and IP5. The Argon gas ionization chambers detect showers produced in the TAN absorbers by neutral particles emerging from pp collisions. The detectors have been operated during the 2010 run by counting the shower rate. As the current 2011 run has the multiplicity of proton-proton collisions per bunch crossing near ten, the detector sees more than one collision per bunch crossing. Therefore, the operation of the detector has been switched to pulse height mode to detect the average shower flux. This paper presents results from recent pulse height mode measurements, including the total and bunch-by-bunch luminosity as well as a determination of the crossing angle at these IPs. Comparisons with luminosity measurements from ATLAS and CMS are also presented. 		 
 
TUPZ002 90 m β* Optics for ATLAS/ALFA optics, emittance, scattering, quadrupole 1798
 
  • S. Cavalier, P.M. Puzo
    LAL, Orsay, France
  • H. Burkhardt
    CERN, Geneva, Switzerland
  • A. Peskov
    NNGU, Nizhny Novgorod, Russia
  
  We describe a high β* optics developed for the ATLAS detector at the LHC interaction regions (IR1), Roman Pots have been installed 240 m left and right of IR1 to allow to measure the absolute luminosity and the total elastic cross section for ATLAS with ALFA (Absolute Luminosity for ATLAS). Ultimately, it is planned to preform these measurements at a very high β* of 2625 m. Here we describe a new, intermediate β* = 90 m optics, which has been optimized for compatibility with the present LHC running conditions. We described the main features and expected performance of this optics for ALFA.  
 
TUPZ005 Design of the NICA Collider Rings collider, ion, lattice, betatron 1807
 
  • O.S. Kozlov, H.G. Khodzhibagiyan, S.A. Kostromin, I.N. Meshkov, A.O. Sidorin, N.D. Topilin, G.V. Trubnikov
    JINR, Dubna, Moscow Region, Russia
  
  The Nuclotron-based Ion Collider fAcility (NICA) is a new accelerator complex being constructed at JINR aimed to provide the collider experiments with ion-ion (Au79+) and ion-proton collisions at the energy range of 1-4.5 GeV/n and also the collisions of polarized proton-proton and deuteron-deuteron beams. Superconducting collider rings accumulate beam injected from Nuclotron and realize the conditions for beam-beam interactions to achieve the required luminosity. Each ring has the racetrack shape with two arcs and two long straight sections. Its circumference is about 500 m. The collider lattice design is subjected to have possibility of the gamma transition variation, mainly by the arcs retuning. The long straight sections contain the most of the insertion devices and are matched to the arcs, optimized to provide the final focusing of the beams in IP and accurate betatron tune adjustment.  
 
TUPZ009 LHC Machine Protection against Very Fast Crab Cavity Failures cavity, optics, betatron, emittance 1816
 
  • T. Baer, R. Tomás, J. Tückmantel, J. Wenninger, F. Zimmermann
    CERN, Geneva, Switzerland
  • T. Baer
    Uni HH, Hamburg, Germany
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  
  For the high-luminosity LHC upgrade program (HL-LHC), the installation of crab cavities (CCs) is essential to compensate the geometric luminosity loss due to the crossing angle. The baseline is a local scheme with CCs around the ATLAS and CMS experiments. In a failure case (e.g. a CC quench), the voltage and/or phase of a CC can change significantly with a fast time constant of the order of a LHC turn. This can lead to large, global betatron oscillations of the beam. Against the background of machine protection, the influence of a CC failure on the beam dynamics is discussed. The results from dedicated tracking studies, including the LHC upgrade optics, are presented. Necessary countermeasures to limit the impact of CC failures to an acceptable level are proposed.  
 
TUPZ013 Calculation Method for Safe Beta* in the LHC emittance, optics, collimation, injection 1828
 
  • R. Bruce, R.W. Assmann, W. Herr, D. Wollmann
    CERN, Geneva, Switzerland
  
  One way of increasing the peak luminosity in the LHC is to decrease the beam size at the interaction points by squeezing to smaller values of beta*. The LHC is now in a regime where safety and stability determines the limit in beta*, as opposed to traditional optics limits. In this paper, we derive a calculation model to determine the safe beta*-values based on collimator settings and operational stability of the LHC. This model was used to calculate the settings for the LHC run in 2011. It was found that beta* could be decreased from 3.5 m to 1.5 m, which has now successfully been put into operation.  
 
TUPZ014 Luminosity Optimization for a Higher-Energy LHC emittance, damping, radiation, proton 1831
 
  • C.O. Domínguez, F. Zimmermann
    CERN, Geneva, Switzerland
  
  A Higher-Energy Large Hadron Collider (HE-LHC) is an option to further push the energy frontier of particle physics beyond the present LHC. A beam energy of 16.5 TeV would require 20-T dipole magnets in the existing LHC tunnel, which should be compared with 7 TeV and 8.33 T for the nominal LHC. Since the synchrotron radiation power increases with the fourth power of the energy, radiation damping becomes significant for the HE-LHC. It calls for transverse and longitudinal emittance control vis-à-vis beam-beam interaction and Landau damping. The heat load from synchrotron radiation, gas scattering, and electron cloud also increases with respect to the LHC. In this paper we discuss the proposed HE-LHC beam parameters; the time evolution of luminosity, beam-beam tune shifts, and emittances during an HE-LHC store; the expected heat load; and luminosity optimization schemes for both round and flat beams.  
 
TUPZ016 First Run of the LHC as a Heavy-ion Collider ion, proton, heavy-ion, injection 1837
 
  • J.M. Jowett, G. Arduini, R.W. Assmann, P. Baudrenghien, C. Carli, M. Lamont, M. Solfaroli Camillocci, J.A. Uythoven, W. Venturini Delsolaro, J. Wenninger
    CERN, Geneva, Switzerland
  
  A year of LHC operation typically consists of an extended run with colliding protons, ending with a month in which the LHC has to switch to its second role as a heavy ion collider and provide a useful integrated luminosity to three experiments. The first such run in November 2010 demonstrated that this is feasible. Commissioning was extremely rapid, with collisions of Pb nuclei achieved within 55 h of first injection. Stable beams for physics data-taking were declared a little over one day later and the final integrated luminosity substantially exceeded expectations.  
 
TUPZ017 Luminosity and Beam Parameter Evolution for Lead Ion Beams in the LHC emittance, simulation, ion, heavy-ion 1840
 
  • J.M. Jowett, R. Bruce, T. Mertens
    CERN, Geneva, Switzerland
  
  Heavy ion beams in the LHC are subject to strong blow-up and debunching effects from intra-beam scattering and luminosity-driven beam losses. The large nuclear charge is at the origin of these effects, both in the cross sections for simple Coulomb scattering and the ultraperipheral interactions occurring in the collisions. We compare predictions from our models with data on luminosity, beam size and intensity evolution from the first heavy ion run of the LHC. This analysis has to take account of the varying capabilities of the LHC beam instrumentation between injection and collision energies.  
 
TUPZ019 Transverse Emittance Preservation through the LHC Cycle emittance, injection, extraction, controls 1843
 
  • V. Kain, B. Goddard, B.J. Holzer, J.M. Jowett, M. Meddahi, T. Mertens, F. Roncarolo
    CERN, Geneva, Switzerland
  
  The preservation of the transverse emittance is crucial for luminosity performance. At the LHC design stage the total allowed emittance increase was set to 7% throughout the LHC cycle. The proton run in 2010 showed that the injectors can provide beams with smaller emittances than nominal and higher bunch intensities. The LHC parameters are well under control and the emittances are kept below nominal until physics. The LHC luminosity goals for the first year of running could therefore be achieved with fewer bunches than initially foreseen. This paper will report on the measured emittance growth at injection from the SPS and the evolution of the emittance through the entire LHC cycle. Sources and possible cures for the observed emittance growth will be discussed.  
 
TUPZ020 Fill Analysis and Experimental Background Observations in the LHC background, vacuum, extraction, monitoring 1846
 
  • Y.I. Levinsen, H. Burkhardt, A. Macpherson, M. Pereira, S.X. Roe
    CERN, Geneva, Switzerland
  
  Funding: Presenting author funded by the University of Oslo
In this work we look at experimental background under different conditions for the early 2011 running. We will discuss the observations in the context of the residual gas pressure, beam halo, and cross-talk between experiments. We have developed a modular fill analysis tool which automatically extracts data and analyses each fill in the LHC. All generated and extracted information is stored for outside use. The tool is applied to aid us in the work presented here. 		 
 
TUPZ021 The SPS Beam Quality Monitor, from Design to Operation injection, extraction, dipole, quadrupole 1849
 
  • G. Papotti, T. Bohl, F. Follin, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  
  The SPS Beam Quality Monitor is a system that monitors longitudinal beam parameters on a cycle-by-cycle basis and prevents extraction to the LHC in case the specifications are not met. This avoids losses, unnecessary stress of machine protection components and luminosity degradation, additionally helping efficiency during the filling process. The system has been operational since the 2009 LHC run, checking the beam pattern, its correct position with respect to the LHC references, individual bunch lengths and stability. In this paper the algorithms used, the hardware implementation and the operational aspects are presented.  
 
TUPZ023 Observation of Bunch to Bunch Differences due to Beam-beam Effects injection, emittance, kicker, dynamic-aperture 1855
 
  • G. Papotti, R. Alemany-Fernandez, R. Giachino, W. Herr, T. Pieloni, M. Schaumann, G. Trad
    CERN, Geneva, Switzerland
  
  Due to the bunch filling schemes in the LHC the bunches experience a very different collision schedule and therefore different beam-beam effects. These differences and the effect on the performance have been observed and compared with the expectations. Possible limitations due to these effects are discussed.  
 
TUPZ025 Experience with Offset Collisions in the LHC target, emittance, beam-losses, controls 1858
 
  • G. Papotti, R. Alemany-Fernandez, F. Follin, R. Giachino, W. Herr, T. Pieloni, M. Schaumann
    CERN, Geneva, Switzerland
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  
  To keep the luminosity under control, some experiments require the adjustment of the luminosity during a fill, so-called luminosity leveling. One option is the separate the beams transversely and adjust the separation to the desired collision rate. The results from controlled experiments are reported and interpreted. The feasibility of this method for ultimate luminosities is discussed.  
 
TUPZ027 Beta* Measurement in the LHC Based on K-modulation quadrupole, optics, simulation, lattice 1864
 
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: This work partially supported by the US Department of Energy through the LHC Accelerator Research Program (LARP).
Accurate knowledge of the collision point optics is crucial to equalize the luminosities at the different experiments. K-modulation was successfully applied at several accelerators for measuring the lattice beta functions. In the LHC, it was proposed as an alternative method to compute the beta* at the collision points. Results of beta* measurements in the LHC based on the K-modulation technique are presented with comparisons to nominal segment-by-segment method. 		 
 
TUPZ032 LHC Luminosity Upgrade with Large Piwinski Angle Scheme: A Recent Look collider, simulation, emittance, single-bunch 1879
 
  • C.M. Bhat
    Fermilab, Batavia, USA
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: Work is supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and US LARP.
Luminosity upgrade at the LHC collider using bunches with constant line charge density (longitudinally flat bunches) but with same beam-beam tune shift at collision, the so called large Piwinski angle scheme* is being studied with renewed interest in recent years**. By design the total beam-beam tune shift at the LHC is less than 0.015. But the initial operational experience at the LHC indicates the possibility of operating with beam-beam tune shifts as high as 0.02. In view of this development we have revisited the requirements for the Large Piwinski Angle scheme at the LHC. In this paper we present a new parameter list supported by 1) calculations on the luminosity gain, 2) reduction of e-cloud issues on nearly flat bunches and 3) longitudinal beam dynamics simulations. We also make some remarks on the needed upgrades on the LHC injector accelerators.
* F. Ruggiero and F. Zimmermann, PRST-AB 5, 061001 (2002).
** C. M. Bhat, CERN-2009-004, pp. 106-114.
Thanks to O.Bruning, E.Shaposhnikova, H.Damerau, E.Mahner, F.Caspers & CERN BE/ABP & RF Depts. 		 
 
TUPZ038 RHIC Performance for FY2011 Au+Au Heavy Ion Run cavity, ion, feedback, heavy-ion 1894
 
  • G.J. Marr, L. A. Ahrens, M. Bai, J. Beebe-Wang, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, C. Carlson, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, W. Fu, C.J. Gardner, D.M. Gassner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, N.A. Kling, M. Lafky, J.S. Laster, C. Liu, Y. Luo, M. Mapes, A. Marusic, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, S. Polizzo, V. Ptitsyn, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, C. Schultheiss, F. Severino, T.C. Shrey, K.S. Smith, D. Steski, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, B. Van Kuik, G. Wang, M. Wilinski, A. Zaltsman, K. Zeno, S.Y. Zhang
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Following the Fiscal Year (FY) 2010 (Run-10) Relativistic Heavy Ion Collider (RHIC) Au+Au run [1], RHIC experiment upgrades sought to improve detector capabilities. In turn, accelerator improvements were made to improve the luminosity available to the experiments for this run (Run-11). These improvements included: a redesign of the stochastic cooling systems for improved reliability; a relocation of “common” RF cavities to alleviate intensity limits due to beam loading; and an improved usage of feedback systems to control orbit, tune and coupling during energy ramps as well as while colliding at top energy. We present an overview of changes to the Collider and review the performance of the collider with respect to instantaneous and integrated luminosity goals. 		 
 
WEZA01 Round Beam Collisions at VEPP-2000* positron, lattice, resonance, betatron 1926
 
  • Y.M. Shatunov, D.E. Berkaev, A.N. Kirpotin, I. Koop, A.P. Lysenko, I. Nesterenko, E. Perevedentsev, Yu. A. Rogovsky, A.L. Romanov, P.Yu. Shatunov, D.B. Shwartz, A.N. Skrinsky, I. Zemlyansky
    BINP SB RAS, Novosibirsk, Russia
  
  The idea of round beams collision was proposed more than 20 years ago for the Novosibirsk Phi-factory design. It requires equal emittances, equal small fractional tunes, equal beta functions at the IP, no betatron coupling in the collider arcs. A 90° rotation at each passage of the transverse oscillation plane by means of solenoids in the interaction regions provides conservation of the longitudinal component of the angular moment. Thus the transverse motion becomes one-dimensional. Such a scheme helps to eliminate all betatron coupling resonances that are of crucial importance for beam-beam tune shift saturation and lifetime degradation. Only recently, the round beam concept was successfully tested at the electron-positron collider VEPP2000 at the energy of 510 MeV. Despite the low energy a high single bunch luminosity of 1031 cm-2s−1 was achieved together with a maximum tune shift as high as 0.1. At present the work is in progress to increase the energy of the collider to explore the range between 510 MeV and 1 GeV in collision.  
slides icon Slides WEZA01 [3.740 MB]  
 
WEZA02 Colliders for B Factories quadrupole, emittance, sextupole, factory 1931
 
  • H. Koiso
    KEK, Ibaraki, Japan
  
  Two new B factories, SuperB in Frascati and SuperKEKB in Tsukuba, aim at unprecedented luminosities close to 1036/cm2/s. The designs, status, challenges, and differences between the two machines are reported. Emphasis should be put on recent developments for the B factories. The presentation should include a realistic outlook.  
slides icon Slides WEZA02 [6.796 MB]  
 
WEODA01 Observations of Beam-beam Effects at High Intensities in the LHC emittance, beam-beam-effects, dynamic-aperture, brightness 1936
 
  • W. Herr, R. Alemany-Fernandez, R. Giachino, G. Papotti, T. Pieloni
    CERN, Geneva, Switzerland
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  • E. Laface
    ESS, Lund, Sweden
  • M. Schaumann
    RWTH, Aachen, Germany
  
  First observations with colliding beams in the LHC with bunch intensities close to nominal and above are reported. In 2010 the LHC initially operated with few bunches spaced around the circumference. Beam-beam tune shifts exceeding significantly the design value have been observed. In a later stage crossing angles were introduced around the experiments to allow the collisions of bunch trains. We report the first experience with head-on as well as long range interactions of high intensity bunches and discuss the possible performance reach.  
slides icon Slides WEODA01 [0.409 MB]  
 
WEODA03 Design Concepts for the Large Hadron Electron Collider linac, electron, cavity, collider 1942
 
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  
  A report is presented on the design concepts for a high luminosity electron-nucleon collider of 1.3 TeV centre of mass energy, realized with the addition of a 60 GeV electron ring or linear accelerator to the existing proton and ion LHC beam facility, comprising machine magnets, optics, interaction region, cryogenics, rf, civil engineering and further components of the LHeC. The report on behalf of the LHeC study team is a summary of the 2011 LHeC CDR and feedback received from an international review panel.  
slides icon Slides WEODA03 [9.780 MB]  
 
WEPC037 An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade optics, insertion, sextupole, quadrupole 2088
 
  • S.D. Fartoukh
    CERN, Geneva, Switzerland
  
  A novel optics concept has been invented and developed in the context of the LHC Upgrade studies. It offers an incredibly powerful and flexible machinery in order to squeeze beta* in a symmetric or asymmetric way (so-called “round” or “flat” optics, respectively), while perfectly controlling the chromatic aberrations induced (off-momentum beta-beating, non-linear chromaticity, spurious dispersion due to the crossing angles). The basic principles of the scheme are described and a specific path for the LHC upgrade is built accordingly, only relying on the existing and well-characterized LHC-like technology, and based on the production of flat collision optics with very small beta* (7.5 cm) in the plane perpendicular to the crossing plane.  
 
WEPC081 Beam-Beam Induced Orbit Effects at LHC simulation, closed-orbit, beam-beam-effects, collider 2208
 
  • M. Schaumann, R. Alemany-Fernandez
    CERN, Geneva, Switzerland
  
  For high bunch intensities the beam-beam force is strong enough to expect orbit effects if the two beams do not collide head-on but with a crossing angle or with a given offset. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are presented in this paper.  
 
WEPC142 High Performance Web Applications for Particle Accelerator Control Systems controls, collider, optics, diagnostics 2322
 
  • G. Mazzitelli, C. Bisegni, P. Ciuffetti, G. Di Pirro, A. Stecchi
    INFN/LNF, Frascati (Roma), Italy
  • S. Calabrò, L.G. Foggetta
    IN2P3-CNRS, Orsay, France
  • L. Catani, F. Zani
    INFN-Roma II, Roma, Italy
  
  The integration of web technologies and applications has been one of the major trends for the development of new services for control systems of particle accelerators and large experimental apparatuses. Nowadays, high performance web technologies exhibit some features that would allow their deeper integration in a control system and their employment in developing control system's core components. In this paper we discuss the results of preliminary investigations of a new paradigm for a particle accelerator control system and associated machine data acquisition system based on a synergic combination of network distributed cache memory and a non-relational key/value database. Storage speed, network memory data retrieve throughput and database queries execution, as well as scalability and redundancy of the systems, are presented and critically reviewed.  
poster icon Poster WEPC142 [8.902 MB]  
 
WEPO026 Advances in the Design of the SuperB Final Doublet quadrupole, collider, controls, positron 2454
 
  • E. Paoloni, N. Carmignani, F. Pilo
    University of Pisa and INFN, Pisa, Italy
  • S. Bettoni
    CERN, Geneva, Switzerland
  • M.E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma), Italy
  • F. Bosi
    INFN-Pisa, Pisa, Italy
  • P. Fabbricatore, S. Farinon, R. Musenich
    INFN Genova, Genova, Italy
  • M.K. Sullivan
    SLAC, Menlo Park, California, USA
  
  SuperB is an asymmetric (6.7 GeV HER, 4.18 GeV LER) e+ e− collider operating at the Y(4S) peak with a design peak luminosity of 1036 Hz/cm2 to be built in Italy in the very near future. The design luminosity is almost a factor hundred higher than that of the present generation comparable facilities. To get the design luminosity a novel collision scheme, the so called “large Piwinski angle with crab waist”, has been designed. The scheme requires a short focus final doublet to reduce the vertical beta function down to betay*=0.2 mm at the interaction point (IP). The final doublet will be composed by a set of permanent and superconducting (SC) quadrupoles. The SC quadrupole doublets QD0/QF1 have to be placed as close to the IP as possible. This layout is critical because the space available for the doublets is very small. An advanced design of the quadrupole has been developed, based on the double helical coil concept. The paper discusses the design concept, the construction and the results of test of a model of the superconducting quadrupole based on NbTi technology. Future developments are also presented.  
 
WEPO027 Design Study of Final Focusing Superconducting Magnets for the SuperKEKB solenoid, focusing, quadrupole, positron 2457
 
  • M. Tawada, N. Higashi, M. Iwasaki, H. Koiso, A. Morita, Y. Ohnishi, N. Ohuchi, K. Oide, T. Oki, K. Tsuchiya, H. Yamaoka, Z.G. Zong
    KEK, Ibaraki, Japan
  
  For SuperKEKB, which is an upgrade project of KEKB, we are studying the design of the final focus quadrupole magnets for the interaction region. The 7 GeV electrons in the high-energy ring and the 4 GeV positrons in the low-energy ring collide at one IP with a finite crossing angle of 83 mrad. For each beam, the final beam focusing system consists of the superconducting quadrupole-doublets. These quadrupole magnets have to meet specifications described below. (1) Because of the small beam separation between two beam lines, the superconducting magnet is designed with thin coils and the conductor size is required to be minimized. (2) Since the beta functions are so large, a large space with a good field quality is required. (3) These magnets must apply the focusing fields on electrons and positrons, independent each other. The quadrupole magnets in the solenoid field of the particle detector are designed without an iron yoke. Consequently, the reduction of the leakage fields from the adjacent beam lines is a critical issue to achieve large dynamic aperture. In this paper we will report the design of final focusing system.  
 
WEPS022 Ions for LHC: Performance of the Injector Chain ion, linac, injection, proton 2529
 
  • D. Manglunki, M. E. Angoletta, P. Baudrenghien, G. Bellodi, A. Blas, T. Bohl, C. Carli, E. Carlier, S. Cettour Cave, M. Chanel, K. Cornelis, H. Damerau, A. Findlay, S.S. Gilardoni, S. Hancock, J.M. Jowett, D. Kuchler, S. Maury, E. Métral, S. Pasinelli, M. Schokker, G. Tranquille, B. Vandorpe, U. Wehrle, J. Wenninger
    CERN, Geneva, Switzerland
  
  The first LHC Pb ion run took place at 1.38 A TeV/c per beam in autumn 2010. After a short period of running-in, the injector chain was able to fill the collider with up to 137 bunches per ring, with an intensity of 108 Pb ions/bunch, about 50% higher than the design value. This yielded a luminosity of 3E25 Hz/cm2, allowing the experiments to accumulate just under 10 inverse microbarn each during the four week run. We review the performance of the individual links of the injector chain, and address the main issues limiting the LHC luminosity, in view of reaching 1026 Hz/cm2 in 2011, and substantially beyond when the LHC energy increases after the long shutdown in 2013-14.  
 
THOAA03 Overview of LHC Beam Loss Measurements beam-losses, quadrupole, proton, collimation 2854
 
  • B. Dehning, A.E. Dabrowski, M. Dabrowski, E. Effinger, J. Emery, E. Fadakis, V. Grishin, E.B. Holzer, S. Jackson, G. Kruk, C. Kurfuerst, A. Marsili, M. Misiowiec, E. Nebot Del Busto, A. Nordt, A. Priebe, C. Roderick, M. Sapinski, C. Zamantzas
    CERN, Geneva, Switzerland
  • E. Griesmayer
    CIVIDEC Instrumentation, Wien, Austria
  
  The LHC beam loss monitoring system based on ionization chambers is used for machine protection, quench prevention and accelerator optimization. After one full year of operation it can be stated that its main functionality, that of the protection of equipment, has proven to be very robust with no issues observed for hundreds of critical beam loss events and the number of false beam aborts well below expectation. In addition the injection, dump and collimation system make regular use of the published loss measurements for system analysis and optimisation, such as the determination of collimation efficiency in order to identify possible intensity limitations as early as possible. Intentional magnet quenches have been performed to verify both the calibration accuracy of the system and the accuracy of the loss pattern predictions from simulations. Tests have also been performed with fast loss detectors based on single- and polycrystalline CVD diamond, which are capable of providing nanosecond resolution time loss structure. This presentation will cover all of these aspects and give an outlook on future performance.  
slides icon Slides THOAA03 [1.972 MB]  
 
THPZ003 The SuperB Project: Accelerator Status and R&D feedback, quadrupole, emittance, injection 3684
 
  • M.E. Biagini, S. Bini, R. Boni, M. Boscolo, B. Buonomo, T. Demma, E. Di Pasquale, A. Drago, L.G. Foggetta, S. Guiducci, S.M. Liuzzo, G. Mazzitelli, L. Pellegrino, M.A. Preger, P. Raimondi, U. Rotundo, C. Sanelli, M. Serio, A. Stecchi, A. Stella, S. Tomassini, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • M.A. Baylac, O. Bourrion, J.-M. De Conto, N. Monseu, C. Vescovi
    LPSC, Grenoble, France
  • K.J. Bertsche, A. Brachmann, Y. Cai, A. Chao, M.H. Donald, R.C. Field, A.S. Fisher, D. Kharakh, A. Krasnykh, K.C. Moffeit, Y. Nosochkov, A. Novokhatski, M.T.F. Pivi, J.T. Seeman, M.K. Sullivan, S.P. Weathersby, A.W. Weidemann, U. Wienands, W. Wittmer, G. Yocky
    SLAC, Menlo Park, California, USA
  • S. Bettoni
    PSI, Villigen, Switzerland
  • A.V. Bogomyagkov, I. Koop, E.B. Levichev, S.A. Nikitin, I.N. Okunev, P.A. Piminov, D.N. Shatilov, S.V. Sinyatkin, P. Vobly
    BINP SB RAS, Novosibirsk, Russia
  • B. Bolzon, M. Esposito
    CERN, Geneva, Switzerland
  • F. Bosi
    INFN-Pisa, Pisa, Italy
  • L. Brunetti, A. Jeremie
    IN2P3-LAPP, Annecy-le-Vieux, France
  • A. Chancé
    CEA, Gif-sur-Yvette, France
  • P. Fabbricatore, S. Farinon, R. Musenich
    INFN Genova, Genova, Italy
  • E. Paoloni
    University of Pisa and INFN, Pisa, Italy
  • C. Rimbault, A. Variola
    LAL, Orsay, France
  • Y. Zhang
    IHEP Beijing, Beijing, People's Republic of China
  
  The SuperB collider project has been recently approved by the Italian Government as part of the National Research Plan. SuperB is a high luminosity (1036 cm-2 s-1) asymmetric e+e− collider at the Y(4S) energy. The design is based on a “large Piwinski angle and Crab Waist” scheme already successfully tested at the DAΦNE Phi-Factory in Frascati, Italy. The project combines the challenges of high luminosity colliders and state-of-the-art synchrotron light sources, with two beams (e+ at 6.7 and e- at 4.2 GeV) with extremely low emittances and small beam sizes at the Interaction Point. As unique features, the electron beam will be longitudinally polarized at the IP and the rings will be able to ramp down to collide at the tau/charm energy threshold with one tenth the luminosity. The relatively low beam currents (about 2 A) will allow for low running (power) costs compared to similar machines. The insertion of beam lines for synchrotron radiation users is the latest feature included in the design. The lattice has been recently modified to accommodate insertion devices for X-rays production. A status of the project and a description of R&D in progress will be presented.  
 
THPZ004 DAΦNE Tune-up for the KLOE-2 Experiment background, closed-orbit, wiggler, coupling 3687
 
  • C. Milardi, D. Alesini, M.E. Biagini, S. Bini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, M. Esposito, L.G. Foggetta, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, S.M. Liuzzo, F. Marcellini, G. Mazzitelli, L. Pellegrino, M.A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • S. Bettoni
    PSI, Villigen, Switzerland
  
  Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11).
In its continuous evolution DAΦNE, the Frascati lepton collider, is starting a new run for the KLOE-2 experiment, an upgraded version of the KLOE one. A new interaction region, based on the high luminosity Crab-Waist collision scheme, has been designed, built and installed. Several machine subsystems have been revised according to innovative design concepts in order to improve beam dynamics. Collimators and shieldings have been upgraded in order to minimize the background rates on the detector during coasting as well as injection operation. A wide measurement campaign has been undertaken to verify and quantify the effect of the modifications and to tune-up the collider in view of the 3 years long data-taking foreseen to deliver ~5 fb-1 to the experiment. 		 
 
THPZ007 Lattice Design of Low Emittance and Low Beta Function at Collision Point for SuperKEKB emittance, dipole, dynamic-aperture, lattice 3693
 
  • Y. Ohnishi, H. Koiso, A. Morita, K. Oide, H. Sugimoto
    KEK, Ibaraki, Japan
  
  Extremely low beta function at the interaction point(IP) and low emittance are necessary to achieve the design luminosity of 8x1035 cm-2 s-1 for a SuperKEKB project. The low emittance with a large Piwinski angle makes this possible with longer bunch longitudinally compared with the vertical beta function at IP. We call this Nano-beam scheme. In this scheme, a beam-beam parameter is realized to be less than 0.09 for the design luminosity. The lattice features, chromaticity corrections, and dynamic aperture are discussed in this article.  
 
THPZ008 Strong-strong Simulations for Super B Factories II simulation, resonance, factory, positron 3696
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  
  Trials for the strong-strong simulation for study of beam-beam effect in large Piwinski angle (LPA) collision adopted in Super B factories. So far a combination method of particle in cell method and soft-Gaussian model has been used. We now show complete strong-strong simulation for LPA collision scheme. Collisions between many slices of two bunches are evaluated by particle in cell method with shifted Green function.  
 
THPZ009 Beam Background Simulation for SuperKEKB/Belle-II background, simulation, scattering, interaction-region 3699
 
  • H. Nakano, H. Yamamoto
    Tohoku University, Graduate School of Science, Sendai, Japan
  • K. Kanazawa, H. Nakayama, Y. Ohnishi
    KEK, Ibaraki, Japan
  • C. Kiesling, S. Koblitz, A. Moll, M. Ritter
    MPI-P, München, Germany
  
  The Belle experiment is now being upgraded to the Belle II experiment designed for a 40 times higher luminosity. Such a high luminosity is realized by the SuperKEKB collider where beam-induced background rates are expected to be much higher than those of KEKB. This poses a serious challenge for the design of the machine-detector interface. We have thus carried out a GEANT4-based beam background simulation for Touschek effect. We describe the method of generating background particles and present the result of simulation.  
 
THPZ010 Beam Background and MDI Design for SuperKEKB/Belle-II background, scattering, radiation, positron 3702
 
  • H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama
    KEK, Tsukuba, Japan
  • H. Nakano
    Tohoku University, Graduate School of Science, Sendai, Japan
  
  The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x1035 cm-2s-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.  
 
THPZ012 Luminosity Enhancement and Performance in BEPCII background, quadrupole, optics, coupling 3708
 
  • Q. Qin, J. Cao, J. Cheng, Y.L. Chi, H. Dong, Z. Duan, D. Ji, W. Kang, S.P. Li, L. Ma, H. Qu, C.H. Wang, G.W. Wang, J.Q. Wang, X.H. Wang, Y. Wei, J. Xing, G. Xu, C.H. Yu, J. Yue, C. Zhang, Y. Zhang
    IHEP Beijing, Beijing, People's Republic of China
  
  The Beijing Electron Positron Collider (BEPC) was upgraded to a factory-like machine –- BEPCII, during last several years. From last November, the BEPCII was commissioned again for its luminosity. Efforts on optics correction including optimizing the strengths of superconducting quadrupoles near the IP, orbits correction concerning beam energy, etc, make the transvers tunes possible to move very close to half integer, bringing a big luminosity increase. The background of the detector is also reduced with beam commissioning, and finally fit the requirements of data taking. Further luminosity commissioing, including coupling optimization, beta-waist tuning, was carried on, and the luminosity reached 6.49·1032 cm-2 s-1 during routine operation. Some measures of luminosity enhancement and the luminosity related accelerator physics issues will be discussed.  
 
THPZ013 A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities cavity, optics, insertion, dynamic-aperture 3711
 
  • R. De Maria, S.D. Fartoukh
    CERN, Geneva, Switzerland
  
  The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme*.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings. 		 
 
THPZ015 Synchrotron Radiation in the Interaction Region for a Ring-Ring and Linac-Ring LHeC radiation, linac, interaction-region, electron 3717
 
  • N.R. Bernard
    UCLA, Los Angeles, California, USA
  • R. Appleby, L.N.S. Thompson
    UMAN, Manchester, United Kingdom
  • N.R. Bernard
    ETH, Zurich, Switzerland
  • B.J. Holzer, R. Tomás, F. Zimmermann
    CERN, Geneva, Switzerland
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  • P. Kostka
    DESY Zeuthen, Zeuthen, Germany
  • B. Nagorny, U. Schneekloth
    DESY, Hamburg, Germany
  
  The Large Hadron electron Collider (LHeC) aims at bringing hadron-lepton collisions to CERN with center of mass energies in the TeV scale. The LHeC will utilize the existing LHC storage ring with the addition of a 60 GeV electron accelerator. The electron beam will be stored and accelerated in either a storage ring in the LHC tunnel (Ring-Ring) or a linac tangent to the LHC tunnel (Linac-Ring). Synchrotron Radiation (SR) in the Interaction Region (IR) of this machine requires an iterative design process in which luminosity is optimized while the SR is minimized. This process also requires attention to be given to the detector as the beam pipe must be designed such that damaging effects, such as out-gasing, are minimized while the tracking remains close to the IP. The machinery of GEANT4 has been used to simulate the SR load in the IR and also to design absorbers/masks to shield SR from backscattering into the detector or propagating with the electron beam. The outcome of these simulations, as well as cross checks, are described in the accompanying poster which characterizes the current status of the IR design for both the Ring-Ring and Linac-Ring options of the LHeC in terms of SR.  
 
THPZ016 Interaction Region Design for a Ring-Ring LHeC quadrupole, electron, optics, proton 3720
 
  • L.N.S. Thompson, R. Appleby
    UMAN, Manchester, United Kingdom
  • N.R. Bernard
    UCLA, Los Angeles, California, USA
  • M. Fitterer
    KIT, Karlsruhe, Germany
  • B.J. Holzer
    CERN, Geneva, Switzerland
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  • P. Kostka
    DESY Zeuthen, Zeuthen, Germany
  • L.N.S. Thompson
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. Using one of the LHC's proton beams, an electron beam of relatively low energy and moderately high intensity provides high luminosity TeV-scale e-p collisions at one of the LHC interaction points, running simultaneously with existing experiments. Two designs are studied; an electron ring situated in the LHC tunnel, and an electron linac. The focus of this paper is on the ring design. Designing an e-p machine presents interesting accelerator physics and design challenges, particularly when considering the interaction region. These include coupled optics, beam separation and unconventional mini-beta focusing schemes. Designs are constrained by an array of interdependent factors, including beam-beam interaction, detector dimensions and acceptance, luminosity and synchrotron radiation. Methods of addressing these complex issues are discussed. The current designs for the LHeC Ring-Ring interaction region and long straight section are presented and discussed, in the context of the project goals and design challenges encountered. Future developments and work are also discussed.  
 
THPZ019 High Luminosity Electron-hadron Collider eRHIC electron, hadron, linac, proton 3726
 
  • V. Ptitsyn, E.C. Aschenauer, J. Beebe-Wang, S.A. Belomestnykh, I. Ben-Zvi, R. Calaga, X. Chang, A.V. Fedotov, H. Hahn, L.R. Hammons, Y. Hao, P. He, A.K. Jain, E.C. Johnson, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, W. Meng, B. Parker, A.I. Pikin, T. Rao, T. Roser, B. Sheehy, J. Skaritka, R. Than, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, Q. Wu, W. Xu
    BNL, Upton, Long Island, New York, USA
  
  We present the design of a future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan adding 20 (30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 1034 cm-2s−1 can be achieved in eRHIC using the low-beta interaction region which a 10 mrad crab crossing. A natural staging scenario of step-by-step increases of the electron beam energy by builiding-up of eRHIC's SRF linacs. We report on the eRHIC design and cost estimates for it stages. We discuss the progress of eRHC R&D projects from the polarized electron source to the coherent electron cooling.  
 
THPZ022 Operation Scheme and Statistics of KEKB injection, cavity, sextupole, factory 3735
 
  • M. Tanaka
    MELCO SC, Tsukuba, Japan
  • Y. Funakoshi
    KEK, Ibaraki, Japan
  
  The KEKB B-Factory(KEKB) started a collision experiment in 1999 and finished in June, 2010. The total operation time of KEKB from fiscal year 2000 was 55657 hours. The breakdowns of operation are physics run 73.8%, machine study 6.8%, machine tuning 4.8%, beam tuning 5.9%, trouble 5.3%, maintenance 2.1% and other 1.3%. The total integrated luminosity was 1041 fb-1 and the maximum peak luminosity was 21.083 nb-1s−1. To increase the peak and integrated luminosity, the continuous injection scheme, the crab cavities and the skew sextupole magnets were effective. We finished over ten year operation of KEKB in June, 2010.  
 
THPZ026 Collimation Dependent Beam Lifetime and Loss Rates in the LHC collimation, insertion, beam-losses, betatron 3744
 
  • D. Wollmann, R.W. Assmann, R. Bruce, F. Burkart, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino
    CERN, Geneva, Switzerland
  
  The four primary collimators in each LHC beam define the smallest aperture. Particles with high betatron amplitudes or momentum offset will therefore hit first a primary collimator. The instantaneous particle loss rate at primary collimators is an important measure for the global lifetime of the beams and a major ingredient to identify collimation induced performance limitations in the LHC. These loss rates have been measured during a number of LHC fills, featuring both "good" fills with high luminosity and "bad" fills with beam instabilities. The beam lifetime at the collimators was then calculated from this data for different cases. The results are presented and interpreted within this paper.  
 
THPZ030 Halo Scrapings with Collimators in the LHC collimation, beam-losses, superconducting-magnet, proton 3756
 
  • F. Burkart, R.W. Assmann, R. Bruce, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino, D. Wollmann
    CERN, Geneva, Switzerland
  • L. Lari
    IFIC, Valencia, Spain
  
  The population of the beam halo has been measured in the LHC with beam scraping experiments. Primary collimators of the LHC collimation system were used to scrape the beam halo at different statuses of the machine (injection, top energy, separated and colliding beams). In addition these measurements were used to calibrate the beam loss monitor signals to loss rates at the primary collimators. Within this paper the halo scraping method, the measured halo distribution and the calibration factors are presented and compared to theoretical predictions.  
 
FRXCA01 First Years Experience of LHC Beam Instrumentation feedback, emittance, beam-losses, instrumentation 3779
 
  • O.R. Jones
    CERN, Geneva, Switzerland
  
  The LHC is equipped with a full suite of sophisticated beam instrumentation which has been essential for rapid commissioning, the safe increase in total stored beam power and the understanding of machine optics and accelerator physics phenomena. This talk will comment on all of these systems and on their contributions to the various stages of beam commissioning. It will include details on: the beam position system and its use for real-time global orbit feedback; the beam loss system and its role in machine protection; total and bunch by bunch intensity measurements; tune measurement and feedback; synchrotron light diagnostics for transverse beam size measurements, abort gap monitoring and longitudinal density measurements. Issues and problems encountered along the way will also be discussed together with the prospect for future upgrades.  
slides icon Slides FRXCA01 [7.322 MB]