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luminosity

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MOPP027 Placet Based Start-to-end Simulations of the ILC with Intra-train Fast Feedback System linac, simulation, emittance, feedback 604
 
  • J. Resta-López, P. Burrows, A. F. Hartin
    JAI, Oxford
  • A. Latina, D. Schulte
    CERN, Geneva
  Integrated simulations are important to assess the reliability of the luminosity performance of the future linear colliders. In this paper we present multi-bunch tracking simulation results for the International Linear Collider (ILC) from the start of the LINAC to the interaction point. The tracking along the LINAC and the beam delivery system is done using the code Placet. This code allows us to introduce cavity wakefield effects, element misalignment errors and ground motion. Static beam based alignment of the LINAC are also considered. The luminosity and beam-beam parameters are calculated using the code Guinea-Pig. In the framework of the Feedback On Nano-second Timescales (FONT) project, we describe and simulate an updated fast intra-train feedback system in order to correct for luminosity degradation mainly due to high frequency ground motion.  
 
MOPP037 Alignment of the CLIC BDS alignment, multipole, simulation, radiation 628
 
  • A. Latina, D. Schulte, R. Tomas
    CERN, Geneva
  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.  
 
MOPP038 Optimizing the CLIC Beam Delivery System radiation, synchrotron, synchrotron-radiation, emittance 631
 
  • R. Tomas
    BNL, Upton, Long Island, New York
  • H.-H. Braun, M. Jorgensen, D. Schulte
    CERN, Geneva
  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.  
 
MOPP045 Study of the Validity of K. Bane's Formulae for the CLIC Accelerating Structure dipole, impedance, RF-structure, target 646
 
  • R. Zennaro
    CERN, Geneva
  The comprehension of short range wake is essential for the design of CLIC. Useful tools are the Karl Bane's formulae which predict the short range wake for periodic 2D symmetry 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. A new fitting of the computational results is proposed for structures with very small aperture. A model for rounded iris structures is also proposed.  
 
TUXG01 Last Year of PEP-II B-Factory Operation feedback, injection, vacuum, controls 946
 
  • J. Seeman
    SLAC, Menlo Park, California
  The PEP II B-Factory at SLAC has been in operation for a decade, delivering luminosity to the BABAR experiment. The design luminosity was successfully reached after one year of operation and since then it has surpassed over four times design at 1.2 x 1034 cm-2sec-1. History of main achievements, high current operation issues, and lessons for the future factories will be presented.  
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TUXG02 High Luminosity Operation, Beam-Beam Effects and Their Compensation in TEVATRON proton, electron, antiproton, collider 951
 
  • V. D. Shiltsev
    Fermilab, Batavia, Illinois
  During the recent years a remarkable increase of the TEVATRON luminosity was achieved. The presentation discusses the collider performance, how this was achieved and illustrates today's limitations. The TEVATRON will shutdown soon but many ideas that emerged from the TEVATRON are of great interest for future (hadron) colliders. As an example, the experience gained at the TEVATRON in understanding of beam-beam effects in hadron colliders and their compensation is highly relevant for future projects. Experimental results of the Tevatron Electron Lenses will be presented and possible use of similar lenses in LHC and RHIC will be discussed.  
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TUOAG02 Commissioning of BEPCII injection, vacuum, optics, electron 959
 
  • J. Q. Wang, L. Ma, C. Zhang
    IHEP Beijing, Beijing
  BEPCII is the upgrade project of Beijing Electron Positron Collider (BEPC), serving continuously for both high energy physics experiment and light soure use. As an e+-e- collider, BEPCII will operate in the beam energy region of 1-2.1 GeV with design luminosity of 1*1033cm-2s-1 at 1.89 GeV. The beam commissioning of BEPCII storage rings started out in Nov. 2006. From Nov. 2006 to Aug. 2007, the phase one commissioning was carried out successfully with the so called backup scheme adopting conventional magnets in the IR intead of the superconducting insertion magnets (SIM). After the SIM was intalled into the interaction region, phase two commissioning began in Oct. 2007. The tuning method for high luminosity but low background was extensively studied during phase two, and the beam current has reached more than 1/3 of the design of 0.91 A. The third phase of beam commissioning is planned in May this year after the detector is moved into the on-line position. It is expected that the luminosity would reach to about 30% of its design specification. This paper describes the procedure of beam commissioning of BEPCII and focuses on results of its second phase.  
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TUOBG01 Observations of Beam-beam Tune Spectrum and Measurement of Coherent Tune Shift at KEKB electron, emittance, positron, betatron 962
 
  • T. Ieiri, Y. Ohnishi, M. Tobiyama, S. Uehara
    KEK, Ibaraki
  KEKB is a double-ring electron/positron collider with a horizontal crossing angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. Under the new crabbing collision as well as the horizontal crossing collision, tune spectra of a colliding bunch were observed on a spectrum analyzer to study beam-beam effects. The beam-beam spectrum showed strong nonlinear resonant phenomena. Considering the nonlinearity, the coherent beam-beam tune shift was measured as a function of the bunch current. It was confirmed that the vertical beam-beam parameter estimated from the coherent beam-beam tune shift agreed with a value obtained from a bunch-by-bunch luminosity monitor. The estimated vertical beam-beam parameter was saturated on a level of about 0.04, which is called a beam-beam limit. We found that the bunch current corresponding to the beam-beam limit was far below the bunch current used in the usual operation.  
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TUPC033 IP BPM Position Error at CLIC due to Secondary Emission from Beam-beam Backgrounds simulation, background, feedback, extraction 1122
 
  • A. F. Hartin, R. Apsimon, P. Burrows, C. I. Clarke, C. Perry, C. Swinson
    OXFORDphysics, Oxford, Oxon
  • G. B. Christian
    ATOMKI, Debrecen
  • B. Constance, H. Dabiri Khah
    JAI, Oxford
  • A. Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Beam-beam background impacts on the IP BPM are studied for the CLIC machine. The large number of coherent pairs ( 1.8×108 charges per BPM strip per bunch crossing) for the CLIC-G default parameter set, potentially leads to a large secondary emission in the BPM strips. Detailed GuineaPig++ and Geant studies reveal, however, that the coherent pairs travel down the extraction line without significant secondary showering. Geant studies of the CLIC incoherent pairs show a flux of secondary emission two orders of magnitude less than that expected for the ILC 1 TeV high luminosity scheme. Since previous studies showed that FONT IP BPM signal distortion for the ILC was of no concern, then it can also be neglected at CLIC.  
 
TUPC040 Measurements of Beam-beam Kick using a Gated Beam-position Monitor under Crabbing Collision at KEKB positron, electron, betatron, beam-beam-effects 1143
 
  • T. Ieiri, H. Fukuma, Y. Funakoshi, M. Masuzawa, K. Ohmi, M. Tobiyama
    KEK, Ibaraki
  KEKB is a double-ring electron/positron collider with a horizontal crossing-angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. A gated beam-position monitor is a tool to measure the beam-beam effects. A beam-beam kick curve was measured by comparing the beam position between colliding and non-colliding bunches, while shifting the beam orbit at the interaction point (IP). An effective horizontal beam size at the IP was obtained from a linear part of the beam-beam kick around the central orbit. The estimated beam size agreed with a calculated value including the dynamic effects. It was confirmed that the effective horizontal beam size was reduced by the crabbing collision, as expected from a calculation with a rigid Gaussian model. When a horizontal orbit offset was larger than a beam size, however, we found that the measured beam-beam kick curve deviated from calculated values using the Gaussian model. The result suggests that the beam profile might enlarge horizontally in the peripheral part.  
 
TUPC065 Luminosity Measurement at DAΦNE for Crab Waist Scheme background, simulation, interaction-region, controls 1203
 
  • M. Boscolo, F. Bossi, B. Buonomo, G. Mazzitelli, F. Murtas, P. Raimondi, G. Sensolini
    INFN/LNF, Frascati (Roma)
  • N. Arnaud, D. Breton, A. Stocchi, V. Variola, B. F. Viaud
    LAL, Orsay
  • P. Branchini
    roma3, Rome
  • F. Iacoangeli, P. Valente
    INFN-Roma, Roma
  • M. Schioppa
    INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza)
  Since the beginning of 2008 the DAΦNE complex started to test the "crabbed scheme" to improve the luminosity performance of the accelerator. In order to ensure a fast, accurate and absolute measurement of the luminosity and to fully understand the background conditions, the new interaction region has been equipped with three different luminosity monitors: a Bhabha calorimeter, a Bhabha GEM tracker and a gamma bremsstrahlung proportional counter. The detectors design, construction, and performance, as well as the first measurements performed at DAΦNE during the crab waist commissioning are here presented. Data are also compared with the Monte Carlo simulations of the full setup. First results acquired during the SIDDHARTA run are supposed to be presented.  
 
TUPC074 Beam Transverse Size Effects on the Transition Radiation Energy Spectrum electron, radiation, photon, diagnostics 1221
 
  • G. L. Orlandi
    ENEA C. R. Frascati, Frascati (Roma)
  A theoretical model for the transition radiation emission by a relativistic electron bunch is here presented. Such a model, based on an extension of the virtual quanta method to the case of high density charged beams, predicts the existence of beam transverse size effects on the short wavelength part of the transition radiation energy spectrum. The relevance of such effects to the transition radiation based beam diagnostics of an electron linear accelerator is discussed. The physical consistency of the proposed theoretical model for the transition radiation emission is demonstrated on the basis of the constraints imposed by the temporal causality and Huygens-Fresnel principles. Further arguments in favour of such a thesis, which concern the relativistic nature of the radiative mechanism, are discussed. A possible experiment, devoted to a crosscheck of the theoretical results in an electron linear accelerator, is also proposed.  
 
TUPD011 The Pulsed Quadrupole Magnet for KEKB Low Energy Ring quadrupole, focusing, positron, electron 1455
 
  • T. Mimashi, T. Ieiri, M. Kikuchi
    KEK, Ibaraki
  • A. Tokuchi, K. Tsuchida
    Nichicon (Kusatsu) Corporation, Shiga
  In the KEKB low energy ring, because of photoelectron clouds, the betatron tune changes along the position in the train. The produced photoelectron gives focusing force to the beam. It is remarkable especially in the vertical tune. Since we have a 500 nanoseconds beam abort gap, the photoelectron focusing force is weaker at the head of train. It means the vertical tune is lower at the head of the train. In order to cancel this tune shift, the pulsed quadrupole magnet was installed. The pulsed quadrupole magnet system and its performance are described.  
 
TUPP027 Electron Energy Dependence of Scrubbing Efficiency to Mitigate E-cloud Formation in Accelerators electron, vacuum, simulation, monitoring 1592
 
  • R. Cimino, M. Commisso, T. Demma, A. G. Grilli, P. Liu, M. Pietropaoli, V. Sciarra
    INFN/LNF, Frascati (Roma)
  • V. Baglin
    CERN, Geneva
  • P. Barone, A. Bonanno
    INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza)
  Recently built and planned accelerators, base their ability to reach design parameters, on the capability to reduce Secondary Electron Yield (SEY) during commissioning, hence mitigating the potentially detrimental effects of e-cloud driven machine limitations. This SEY reduction (called "scrubbing"), is due to the fact that the electrons of the cloud, hit the vacuum chamber wall, modifying its surface properties and reducing its SEY. This minimise any disturbing effects of the e-cloud to the beam. "Scrubbing" has been studied only as a function of impinging electron dose. In reality SEY modifications are only studied by bombarding surfaces with 300-500 eV electrons, but no scrubbing dependence on the bombarding electron energy has ever been discussed. The actual energy of the electrons of the cloud hitting the wall in real accelerators has never been measured accurately, while simulations predict very low electron energies (<50 eV). For this reason and given the peculiar behaviour observed for low energy electrons*, we decided to study this dependence accurately. Here we present some preliminary results discussing eventual implications to machine commissioning procedures.

*R. Cimino et al. Phys. Rev. Lett 93, 14801 (2004).

 
 
TUPP046 Tunable Ferroelectric Based Technologies for Accelerator Components controls, linac, insertion, vacuum 1646
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • S. Kazakov
    KEK, Ibaraki
  • E. Nenasheva
    Ceramics Ltd., St. Petersburg
  • A. Tagantsev
    EPFL, Lausanne
  • V. P. Yakovlev
    Fermilab, Batavia, Illinois
  Low loss ferroelectric materials can be used as key elements in RF tuning and phase shifting components to provide fast, electronic control. These devices are under development for different accelerator applications in X, Ka and L - frequency bands. The exact design of these devices depends on the electrical parameters of the particular ferroelectric material to be used- its dielectric constant, loss tangent and tunability. BST based ferroelectric-oxide compounds have been found to be suitable materials for a fast electrically-controlled tuner for BNL and for high-power fast RF phase shifters to be used for SNS vector modulation applications. We present recent results on the development of BST based ferroelectric compositions synthesized for use in high power technology components. The BST(M) ferroelectrics have been tested using a transverse dc bias field. The tunability factor vs. dc field magnitude has been evaluated and the feasibility of transverse bias tuning for ferroelectric based accelerator components has been demonstrated.  
 
TUPP053 Radiolocation of a HOM Source in the PEP-II Rings vacuum, single-bunch, coupling, impedance 1664
 
  • A. Novokhatski, J. Seeman, M. K. Sullivan
    SLAC, Menlo Park, California
  A signal from the antenna situated in the LER (Low Energy Ring) helped to find a broken shielded bellows in the HER (High Energy Ring) during a single HER bunch operation.  
 
TUPP055 Loss Factor of the PEP-II Rings radiation, synchrotron, resonance, synchrotron-radiation 1670
 
  • A. Novokhatski, M. K. Sullivan
    SLAC, Menlo Park, California
  RF power balance method is used to measure the synchrotron radiation losses and the wake field losses. We present the history of the loss factor during the last several runs, which reveals many interesting correlations with vacuum chamber improvement and processing.  
 
TUPP061 Comparison between Laboratory Measurements, Simulations and Analytical Predictions of the Resistive Wall Transverse Beam Impedance at Low Frequencies impedance, simulation, coupling, damping 1679
 
  • F. Roncarolo
    UMAN, Manchester
  • F. Caspers, T. Kroyer, E. Métral
    CERN, Geneva
  • B. Salvant
    EPFL, Lausanne
  The prediction of the resistive wall transverse beam impedance at the first unstable betatron line (8 kHz) of the CERN Large Hadron Collider (LHC) is of paramount importance for understanding and controlling the related coupled-bunch instability. Until now only novel analytical formulas were available at this frequency. Recently, laboratory measurements and numerical simulations were performed to crosscheck the analytical predictions. The experimental results based on the measurement of the variation of a probe coil inductance in the presence of i) sample graphite plates, ii) stand-alone LHC collimator jaws and iii) a full LHC collimator assembly are presented in detail. The measurement results are compared to both analytical theories and simulations. In addition, the consequences for the understanding of the LHC impedance are discussed.  
 
TUPP071 Development of TiN Coating System for Beam Ducts of KEK B-factory electron, cathode, positron, controls 1700
 
  • K. Shibata, H. Hisamatsu, K.-I. Kanazawa, M. Shirai, Y. Suetsugu
    KEK, Ibaraki
  A titanium nitride (TiN) coating system for the copper beam ducts of KEK B-factory (KEKB) was developed to reduce the secondary electron yield (SEY) from the inner surface, which would mitigate the electron cloud instability. The coating was done by DC magnetron sputtering of titanium in argon and nitrogen atmospheres. The duct was set vertically, and a titanium cathode rod was hung from the top on the center axis of the duct. A magnetic field was supplied by a movable solenoid coil placed outside of the duct. Preliminary experiments using small copper samples showed that a 200-nanometer-thick TiN film coated at 150 degree is the best from the viewpoints of SEY and adhesion strength. The SEY of the coated sample decreased to 60% of that of non-coated copper after an electron dose of 0.01 C/mm2, and the maximum SEY was 0.84. Using this system, five ducts with a length of up to 3.6 m were successfully coated. Some of them were installed into the KEKB positron ring last summer, and no problem was found in the following beam operation with a beam current of up to 1.6 A. One coated duct with an electron monitor was installed this winter, and the effect of the coating will be checked.  
 
TUPP079 Distortion of Crabbed Bunch due to Electron Cloud with Global Crab electron, betatron, optics, positron 1715
 
  • L. Wang, Y. Cai, T. O. Raubenheimer
    SLAC, Menlo Park, California
  In order to improve the luminosity, crab cavities have been installed in the KEKB HER and LER. Since there is only one crab cavity in each ring, the crab cavity generates a horizontally titled bunch oscillating around the whole ring. The electron cloud in LER (positron beam) may distort the crabbed bunch and cause the luminosity drop. This paper briefly estimates the distortion of positron bunch due to the electron cloud with global crab.  
 
WEXG01 Performance of KEKB with Crab Cavities simulation, resonance, coupling, collider 1893
 
  • Y. Funakoshi
    KEK, Ibaraki
  20 years after they were initially proposed, in February 2007 crab cavities are for the first time installed in an operating collider, KEKB. The commissioning of KEKB with crab cavities is presented, and the performance of the collider is compared to the performance without crab cavities. Lessons learned from the operation with such cavities for future projects are discussed.  
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WEXG02 Crabbed Waist Collisions in DAΦNE and Super-B Design collider, injection, emittance, interaction-region 1898
 
  • P. Raimondi, D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, C. Milardi, F. Murtas, L. Pellegrino, M. A. Preger, L. Quintieri, 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)
  • N. Arnaud, D. Breton, P. Roudeau, A. Stocchi, V. Variola, B. F. Viaud
    LAL, Orsay
  • S. Bettoni
    CERN, Geneva
  • P. Branchini
    roma3, Rome
  • M. Esposito
    Rome University La Sapienza, Roma
  • I. Koop, E. B. Levichev, P. A. Piminov, D. N. Shatilov, V. V. Smaluk
    BINP SB RAS, Novosibirsk
  • K. Ohmi
    KEK, Ibaraki
  • E. Paoloni
    University of Pisa and INFN, Pisa
  • M. Schioppa
    INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza)
  • D. Teytelman
    SLAC, Menlo Park, California
  • P. Valente
    INFN-Roma, Roma
  The new idea of increasing the luminosity of a collider with crabbed waist collisions and first experimental results from DAΦNE using this concept are presented. Consequences for the design of future factories will be discussed. An outlook to the performance reach with crabbed waist collisions is given, with emphasis on future B Factories.  
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WEOAG01 Prospects for a Large Hadron Electron Collider (LHeC) at the LHC collider, hadron, ion, lepton 1903
 
  • M. Klein
    Liverpool University, Science Faculty, Liverpool
  • H. Aksakal
    N. U, Nigde
  • F. Bordry, H.-H. Braun, O. S. Brüning, H. Burkhardt, R. Garoby, J. M. Jowett, T. P.R. Linnecar, K. H. Mess, J. A. Osborne, L. Rinolfi, D. Schulte, R. Tomas, J. Tuckmantel, F. Zimmermann, A. de Roeck
    CERN, Geneva
  • S. Chattopadhyay, J. B. Dainton
    Cockcroft Institute, Warrington, Cheshire
  • A. K. Ciftci
    Ankara University, Faculty of Sciences, Tandogan/Ankara
  • A. Eide
    EPFL, Lausanne
  • B. J. Holzer
    DESY, Hamburg
  • P. Newman
    Birmingham University, Birmingham
  • E. Perez
    CEA, Gif-sur-Yvette
  • S. Sultansoy
    TOBB ETU, Ankara
  • A. Vivoli
    LAL, Orsay
  • F. J. Willeke
    BNL, Upton, New York
  The LHeC collides a lepton beam with one of the intense, LHC, hadron beams. It achieves both e± interactions with quarks at the terascale, at eq masses in excess of 1 TeV, with a luminosity of about 1033 cm-2 s-1, and it also enables a sub-femtoscopic probe of hadronic matter at unprecedented chromodynamic energy density, at Bjorken-x values down to 10-6 in the deep inelastic scattering domain. The LHeC combines the LHC infrastructure with recent advances in radio-frequency, in linear acceleration and in other associated technologies, to enable two proposals for TeV ep collisions: a "ring-ring" option in which 7 TeV protons (and ions) collide with about 70 GeV electrons/positrons in a storage ring in the LHC tunnel and a "linac-ring" option based on an independent superconducting linear accelerator enabling single-pass collisions of electrons and positrons of up to about 140 GeV with an LHC hadron beam. Both options will be presented and compared. Steps are outlined for completing a Conceptual Design Review of the accelerator complex, beam delivery, luminosity, physics and implications for experiment, following declared support by ECFA and by CERN for a CDR.  
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WEPC060 Studies on the Beam Current Dependent Phenomena in the BEPC-II Storage Rings vacuum, single-bunch, electron, synchrotron 2130
 
  • Q. Qin, N. Huang, W. B. Liu, Y. D. Liu, Y. M. Peng, J. Qiu, D. Wang, J. Q. Wang, N. Wang, X. H. Wang, Y. Wei, X. M. Wen, J. Xing, G. Xu, C. H. Yu, C. Zhang, Y. Zhang, Z. Zhao, D. M. Zhou
    IHEP Beijing, Beijing
  The upgrade project of the Beijing Electron Positron Collider (BEPC-II) has been being commissioned since Nov. 2006. Besides the commissioning of the luminosity, which is expected to be 100 times higher than the BEPC, the BEPC-II also provided beam to the synchrotron radiation users as a light source during these two years. Some beam current dependent phenomena, such as bunch lengthening, single beam instabilities, blow-up in collision, etc., in both collision and synchrotron radiation modes are observed in the machine performance. In this paper, some observations and analyses on these phenomena are given.  
 
WEPD005 Scaling Laws for Magnetic Energy in Superconducting Quadrupoles quadrupole, collider, superconducting-magnet, positron 2407
 
  • F. Borgnolutti, E. Todesco
    CERN, Geneva
  • A. Mailfert
    ENSEM, Vandoeuvre lès Nancy
  The stored energy in superconducting magnets is one of the main ingredients needed for the quench calculation and for desingin quench protections. Here we proposed an analytical formula based on the Fourier transformation of the current density flowing within the winding to determine the magnetic energy stored in superconducting quadrupoles made of sector coils. Two corrective coefficients allowing to estimate the energy enhancement produced either by current grading or by the presence of an unsaturated iron yoke are respectively derived from a numerical and an analytical study. This approach is applied to a set of real quadrupoles to test the validity limits of the scaling law, which are shown to be of 5-10%.  
 
WEPD009 The CERN High Field Magnet Program dipole, quadrupole, radiation, insertion 2419
 
  • G. De Rijk
    CERN, Geneva
  With the LHC, magnets of 10T peak field Nb-Ti technology were developed and this technology reached full maturity. The next step in field level, with a peak field in the range of 15T, will be needed for the LHC phase II upgrade. For this upgrade the temperature margin and radiation resistance of the Nb-Ti coil technology is not sufficient. Begin 2008 CERN starts a program to develop high field magnets for LHC upgrades and other future programs. For this mostly Nb3Sn conductors will be employed but also HTS conductors will be considered. In this paper an overview will be presented of the projects for which this HFM technology will be needed. The the program will be presented in terms of R&D chapters and work packages. The need and opportunities for collaborations with other institutes will be discussed.  
 
WEPD025 A Feasibility Study of Superconducting Dipole for the Early Separation Scheme of SLHC dipole, separation-scheme, shielding, simulation 2461
 
  • G. Sterbini, D. Tommasini
    CERN, Geneva
  In the framework of the LHC luminosity upgrade an early separation scheme is being studied for the final phase (L~1035 cm-2 s-1 with substantial changes in the IR). In this paper we compare a Nb3Sn and a Nb-Ti cos(θ) design: the aim is to explore the benefits and the limits of a compact solution with respect to the detector's constraints and the energy deposition issues. We propose to put the dipole system (cryostat and magnet) at a location starting at 6.8 m from the IP. The preliminary cross section, the achievable integrated field, the energy deposition on the magnet are presented and discussed.  
 
WEPD037 Nb3Sn Quadrupoles in the LHC IR Phase I Upgrade quadrupole, optics, dipole, coupling 2491
 
  • A. V. Zlobin, J. A. Johnstone, V. Kashikhin, N. V. Mokhov, I. L. Rakhno
    Fermilab, Batavia, Illinois
  • S. Peggs, G. Robert-Demolaize, P. Wanderer, R. de Maria
    BNL, Upton, Long Island, New York
  After some years of operation at nominal parameters, the LHC will be upgraded for higher luminosity. At the present time it is planned to perform the IR upgrade in two phases with the target luminosity for Phase I of ~2.5· 1034 cm-2s-1 and up to 1035 cm-2s-1 for Phase II. In Phase I the baseline 70-mm NbTi low-beta quadrupoles will nominally be replaced with larger aperture NbTi magnets and in Phase II with higher performance Nb3Sn magnets. U. S.-LARP is working on the development of large aperture high-performance Nb3Sn magnet technologies for the LHC Phase II luminosity upgrade. Recent progress also suggests the possibility of using Nb3Sn quadrupoles in the Phase I upgrade, improving the luminosity through an early demonstration of Nb3Sn magnet technology in a real accelerator environment. This paper discusses the possible hybrid optics layouts for Phase I upgrades with both NbTi and Nb3Sn quadrupoles, introducing magnet parameters and issues related to using Nb3Sn quadrupoles including magnet length and aperture limitations, field quality, operation margin, etc. Possible transition scenarios to Phase II are also discussed.  
 
WEPP003 Optics Flexibility in the LHC at Top Energy optics, injection, quadrupole, betatron 2524
 
  • M. Aiba, H. Burkhardt, S. D. Fartoukh, M. Giovannozzi, S. M. White
    CERN, Geneva
  We report on studies of optics flexibility which allow for tune changes of the order of half a unit at top energy in the LHC. We describe how this could be done using one or several of the insertions IR2, IR4, IR8 or the main quadrupoles and discuss and compare the implications. This flexibility could be used to compensate for the loss in tune for high beta optics and may make it feasible to use the standard injection and ramp for these configurations. Potential further applications are also highlighted.  
 
WEPP004 Overall Optics Solutions for Very High Beta in Atlas optics, insertion, emittance, injection 2527
 
  • S. M. White, H. Burkhardt, P. M. Puzo
    CERN, Geneva
  • S. Cavalier, M. Heller
    LAL, Orsay
  An insertion optics with a beta-star of at least 2600 m has been requested by the ATLAS experiment at the LHC. This is very far from the standard LHC physics optics and implies a significant reduction in the phase advance from this insertion corresponding to about half a unit in tune. We describe several alternatives how this could be integrated in overall LHC optics solutions with the possibility to inject, ramp and un-squeeze to the required very high beta.  
 
WEPP006 Effects of Ultraperipheral Nuclear Collisions in the LHC and their Alleviation ion, simulation, collimation, beam-losses 2533
 
  • R. Bruce, S. S. Gilardoni, J. M. Jowett
    CERN, Geneva
  Electromagnetic interactions between colliding heavy ions at the LHC are the sources of specific beam loss mechanisms that may quench superconducting magnets. We propose a simple yet efficient strategy to alleviate the effect of localized losses from bound-free pair production by spreading them out in several magnets by means of orbit bumps. We also consider the consequences of neutron emission by electromagnetic dissociation and show through simulations that ions modified by this process will be intercepted by the collimation system, without further modifications.  
 
WEPP007 Crab Compensation for LHC Beams impedance, damping, optics, collimation 2536
 
  • R. Calaga
    BNL, Upton, Long Island, New York
  • Y. Sun, R. Tomas, F. Zimmermann
    CERN, Geneva
  An R&D program to establish a road map for the installation of crab cavities in the LHC is rapidly advancing. Both local and global crab schemes are under investigation to develop cavities that will be compatible with LHC optics and meet aperture requirements. The design of a prototype TM110 cavity and pertinent RF requirements including impedance estimates and damping are discussed. Some alternate cavity designs are also explored. The required optics modifications to accommodate the crab cavities and some particle stability studies are presented.  
 
WEPP008 Localizing Sources of Horizontal Orbit Oscillations at RHIC closed-orbit, emittance, focusing, feedback 2539
 
  • R. Calaga, R. J. Michnoff, T. Satogata
    BNL, Upton, Long Island, New York
  Horizontal oscillations of the closed orbit at frequencies around 10Hz are observed at RHIC. These oscillations lead to beam beam offsets at the collision point, resulting in emittance growth and reduced luminosity. An approach to localize the sources of these vibrations using a special mode of RHIC turn-by-turn BPM data is presented. Data from the 2005-06 are analyzed to spatially resolve the location of the dominant sources.  
 
WEPP011 Setup and Performance of RHIC for the 2008 Run with Deuteron and Gold Collisions ion, injection, lattice, feedback 2548
 
  • C. J. Gardner, N. P. Abreu, L. Ahrens, J. G. Alessi, M. Bai, D. S. Barton, J. Beebe-Wang, M. Blaskiewicz, J. M. Brennan, K. A. Brown, D. Bruno, J. J. Butler, P. Cameron, C. Carlson, R. Connolly, T. D'Ottavio, A. J. Della Penna, K. A. Drees, W. Fischer, W. Fu, G. Ganetis, J. W. Glenn, M. Harvey, T. Hayes, H. Huang, P. F. Ingrassia, J. Kewisch, R. C. Lee, V. Litvinenko, Y. Luo, W. W. MacKay, M. Mapes, G. J. Marr, A. Marusic, R. J. Michnoff, C. Montag, J. Morris, B. Oerter, F. C. Pilat, E. Pozdeyev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, T. Russo, P. Sampson, J. Sandberg, T. Satogata, C. Schultheiss, F. Severino, K. Smith, D. Steski, S. Tepikian, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, K. Zeno, S. Y. Zhang
    BNL, Upton, Long Island, New York
  This year deuterons and gold ions were collided in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) for the first time since 2003. The setup and performance of the collider for this run is reviewed with a focus on improvements that have led to an order of magnitude increase in luminosity since the 2003 run.  
 
WEPP013 Increasing the Integrated Luminosity of SLHC by Levelling via the Crossing Angle simulation, separation-scheme, beam-beam-effects, dipole 2554
 
  • J.-P. Koutchouk, G. Sterbini
    CERN, Geneva
  • K. Ohmi
    KEK, Ibaraki
  With an increase of luminosity by a factor of 10, the luminosity lifetime in an upgraded LHC would be limited to a few hours. Furthermore, schemes relying on stronger focusing and reduced beam current increase (which are intrisically less dangerous for machine protection) are penalized by a very short lifetime of around 2 hours. We show in this paper that the "early separation" scheme and/or crab cavities scheme lend themselves to a very efficient luminosity leveling scheme. It allows constant luminosity over many hours as well as a significant increase of integrated luminosity above the performance announced so far. This is achieved by adjusting the crossing angle rather than the beam size by means of a bump closed inside the experimental straight section, i.e. operationally simple. The initially large crossing angle reduces the beam-beam tune shift, allowing an increased beam current and higher performance for lower pile-up in the detector and lower energy deposition in the triplet. The impact of the required large Piwinski angle is investigated.  
 
WEPP015 Experience with IBS-suppression Lattice in RHIC lattice, ion, emittance, heavy-ion 2557
 
  • V. Litvinenko, M. Bai, D. Bruno, P. Cameron, R. Connolly, A. J. Della Penna, K. A. Drees, A. V. Fedotov, G. Ganetis, L. T. Hoff, W. Louie, Y. Luo, N. Malitsky, G. J. Marr, A. Marusic, C. Montag, F. C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, S. Tepikian, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York
  An intra-beam scattering (IBS) is the limiting factor of the luminosity lifetime for RHIC operating with heavy ions. In order to suppress the IBS we designed and implemented new lattice with higher betatron tunes. This lattice had been developed during last three years and had been used for gold ions in yellow ring of the RHIC during d-Au part of the RHIC Run-8. The use of this lattice allowed both significant increases in the luminosity lifetime and the luminosity levels via reduction of beta-stars in the IPs. In this paper we report on the development, the tests and the performance of IBS-suppression lattice in RHIC, including the resulting increases in the peak and the average luminosity. We also report on our plans for future steps with the IBS suppression.  
 
WEPP016 FEL-based Coherent Electron Cooling for High-energy Hadron Colliders hadron, electron, collider, emittance 2560
 
  • V. Litvinenko
    BNL, Upton, Long Island, New York
  • Y. S. Derbenev
    Jefferson Lab, Newport News, Virginia
  Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation of such beams is too feeble and two common methods, stochastic and electron cooling, are not efficient in providing significant cooling for high energy hadron, especially proton, colliders. In this paper we discuss a practical scheme of Coherent Electron Cooling, which promises short cooling times (below one hour) for intense proton beams in RHIC at 250 GeV or in LHC at 7 TeV*. Coherent Electron Cooling was suggested early 1980s as a possibility for using various microwave instabilities in an electron beam to enhance its interaction with hadrons**. The capabilities of present-day accelerator technology, ERLs, and high-gain Free-Electron Lasers (FELs), finally caught up with the idea and provided the all necessary ingredients for realizing such a process at energies typical for modern high energy hadron colliders. In this paper, we discuss the principles, the main limitations of this scheme and present some predictions for Coherent Electron Cooling in RHIC and the LHC operating with ions or protons.

*V. N. Litvinenko, Y. S. Derbenev, Proc. 29th Int. FEL Conference, Novosibirsk, August, 2007.
**Y. S. Derbenev, Proc. of 7th All-Union Conf. on Charged Particle Accelerators, October 1980, Dubna, 269.

 
 
WEPP019 RHIC Polarized Proton Performance in Run-8 proton, polarization, emittance, collider 2566
 
  • C. Montag, N. P. Abreu, L. Ahrens, M. Bai, D. S. Barton, A. Bazilevsky, J. Beebe-Wang, M. Blaskiewicz, J. M. Brennan, K. A. Brown, D. Bruno, G. Bunce, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, K. A. Drees, A. V. Fedotov, W. Fischer, G. Ganetis, C. J. Gardner, J. W. Glenn, T. Hayes, H. Huang, P. F. Ingrassia, A. Kayran, J. Kewisch, R. C. Lee, V. Litvinenko, A. U. Luccio, Y. Luo, W. W. MacKay, Y. Makdisi, N. Malitsky, G. J. Marr, A. Marusic, R. J. Michnoff, J. Morris, B. Oerter, H. Okada, F. C. Pilat, P. H. Pile, G. Robert-Demolaize, T. Roser, T. Russo, T. Satogata, C. Schultheiss, M. Sivertz, K. Smith, S. Tepikian, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S. Y. Zhang
    BNL, Upton, Long Island, New York
  During Run-8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin-polarized proton beams at two interaction regions. Helical spin rotators at these two interaction regions were used to control the spin orientation of both beams at the collision points. Physics data were taken with different orientations of the beam polarization. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run-8.  
 
WEPP029 Project of the Nuclotron-based Ion Collider Facility (NICA) at JINR ion, collider, electron, heavy-ion 2581
 
  • G. V. Trubnikov, N. N. Agapov, V. Alexandrov, A. V. Butenko, E. E. Donets, A. V. Eliseev, A. Govorov, V. Kekelidze, H. G. Khodzhibagiyan, V. Kobets, A. D. Kovalenko, O. S. Kozlov, A. Kuznetsov, I. N. Meshkov, V. A. Mikhaylov, V. Monchinsky, V. Shevtsov, A. O. Sidorin, A. N. Sissakian, A. V. Smirnov, A. Sorin, V. Toneev, V. Volkov, V. Zhabitsky
    JINR, Dubna, Moscow Region
  • O. I. Brovko, I. Issinsky
    JINR/LHE, Moscow
  The Nuclotron-based Ion Collider fAcility (NICA) is the new accelerator complex being constructed at JINR aimed to provide collider experiments with heavy ions up to uranium at maximum energy (center of mass) equal to 9 GeV/u. It includes new 6 Mev/u linac, 440 MeV/u booster, upgraded SC synchrotron Nuclotron and collider consisting of two SC rings, which provide average luminosity of 1027cm-2s-1. General goal of the project is to start in the coming 5-7 years experimental study of hot and dense strongly interacting QCD matter and search for possible manifestation of signs of the mixed phase and critical endpoint in heavy ion collisions. The NICA and the Multi Purpose Detector (MPD) are proposed for these purposes. Accelerator complex NICA is being built on the experience and technological developments at the Nuclotron facility and incorporates new technological concepts. The new facility will allow also an effective acceleration of light ions to the Nuclotron maximum energy and an increase of intensity of polarized deuteron beams up to the level above 1010 particles/cycle. The scheme of the facility, its operation scenario and beam dynamics are presented in the report.  
 
WEPP030 LHC Luminosity Upgrade: Protecting Insertion Region Magnets from Collision Debris shielding, insertion, cryogenics, dipole 2584
 
  • E. Y. Wildner, F. Cerutti, A. Ferrari, M. Mauri, A. Mereghetti
    CERN, Geneva
  The Large Hadron Collider built at CERN now enters a starting-up phase where with the present design luminosities up to 1034 cm-2 s-1 will be reached after the running in phase. A possible upgrading of the machine to luminosities up to 1035 cm-2 s-1 requires a completely new insertion region design, and will be implemented in essentially two phases. The energy from collision debris is deposited in the insertion regions and in particular in the superconducting magnet coils with a possible risk of quench. We describe here how to protect the interaction region magnets against this irradiation to keep the energy deposition below critical values estimated for safe operation. The constraint is to keep the absorber size as small as possible to leave most of the magnet aperture available for the beam. This can be done by choosing a suitable material and design minimizing the load on the cryogenic system. We will describe a proposal of a design for the phase I upgrade lay-out (i.e., luminosities up to 2.5 1034 cm-2 s-1).  
 
WEPP031 Energy Deposited in the High Luminosity Inner Triplets of the LHC by Collision Debris quadrupole, insertion, superconducting-magnet, kaon 2587
 
  • E. Y. Wildner, F. Cerutti, A. Ferrari, C. Hoa, J.-P. Koutchouk
    CERN, Geneva
  • F. Broggi
    INFN/LASA, Segrate (MI)
  • N. V. Mokhov
    Fermilab, Batavia, Illinois
  The 14 TeV center of mass proton-proton collisions in the LHC produce not only interesting events for physics but also debris ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of the deposited heat, that has to be transferred to the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC baseline are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the comparison and consolidation of the calculations, a dedicated study of a simplified model has been made, showing satisfactory agreement.  
 
WEPP032 Parametric Study of Energy Deposition in the LHC Inner Triplet for the Phase 1 Upgrade quadrupole, interaction-region, dipole, insertion 2590
 
  • E. Y. Wildner, F. Borgnolutti, F. Cerutti, M. Mauri, A. Mereghetti, E. Todesco
    CERN, Geneva
  To be able to make a global parametric analysis and to have some basic understanding of the influence of critical parameters, scaling laws may be of help. For the design of the LHC collision insertion regions, one of the critical parameters is the energy deposited in the insertion superconducting magnet coils, to avoid magnet quench, too heavy load on the cryogenic system, and degradation of the superconductor due to radiation. The influence on energy deposition of some key parameters for magnet design, such as the magnet apertures, the magnet lengths and positions, has been studied for some specified optical beta-value at the collision point.  
 
WEPP034 Study of Beam-beam effect at various collision scheme in LHC simulation, emittance, resonance, proton 2593
 
  • K. Ohmi
    KEK, Ibaraki
  LHC is designed as two major collision points with finite crossing angle of 140μrad (half). The Piwinski angle is 0.4 for the design. Upgrade plans have been studied to increase the luminosity 10 times. Large Piwinski angle scheme is one of the option for the upgrade. The one turn map with the two beam-beam interactions can be expanded by Taylor series. Analyzing the one turn map gives information of resonance behavior of the beam-beam interactions. We discuss the one turn map for the design LHC and upgrade scheme.  
 
WEPP035 Study of Beam-beam Issue for KEKB Crab Crossing coupling, lattice, resonance, simulation 2596
 
  • K. Ohmi, J. W. Flanagan, Y. Funakoshi, N. Iida, H. Koiso, A. Morita, Y. Ohnishi, K. Oide, Y. Seimiya
    KEK, Ibaraki
  A short lifetime at collision is one of the limits on luminosity performance at KEKB in crab crossing mode. The beam-beam halo was evaluated via simulation. The beam lifetime and profile were measured for various beam conditions, vertical emittances, tunes and collision offsets. We discuss why the lifetime is shortened by the beam-beam interaction.  
 
WEPP036 DAΦNE Setup and Operation with the Crab-Waist Collision Scheme sextupole, injection, collider, vacuum 2599
 
  • C. Milardi, D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, F. Murtas, 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)
  • N. Arnaud, D. Breton, P. Roudeau, A. Stocchi, V. Variola, B. F. Viaud
    LAL, Orsay
  • S. Bettoni
    CERN, Geneva
  • P. Branchini
    roma3, Rome
  • M. Esposito
    Rome University La Sapienza, Roma
  • I. Koop, E. B. Levichev, P. A. Piminov, D. N. Shatilov
    BINP SB RAS, Novosibirsk
  • K. Ohmi
    KEK, Ibaraki
  • E. Paoloni
    University of Pisa and INFN, Pisa
  • M. Schioppa
    INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza)
  • V. V. Smaluk
    BINP, Novosibirsk
  • P. Valente
    INFN-Roma, Roma
  In the second half of 2007 a major upgrade has been implemented on the Frascati DAΦNE collider in order to test the novel idea of Crab Waist collisions. New vacuum chambers and permanent quadrupole magnets have been designed, fabricated and installed to realize the new configuration. At the same time the performances of relevant hardware components, such as fast injection kickers and shielded bellows have been improved relying on new design concepts. The collider has been successfully commissioned in this new configuration. The paper describes the new layout as well as several experimental results about linear and non-linear optics setup and optimization, damping of beam instabilities and discusses the obtained luminosity performances.  
 
WEPP039 Design of a 1036 cm-2 s-1 Super-B Factory interaction-region, collider, injection, emittance 2605
 
  • J. Seeman, K. J. Bertsche, A. Novokhatski, M. K. Sullivan, U. Wienands, W. Wittmer
    SLAC, Menlo Park, California
  • S. Bettoni
    CERN, Geneva
  • M. E. Biagini, R. Boni, M. Boscolo, T. Demma, A. Drago, S. Guiducci, P. Raimondi, S. Tomassini, M. Zobov
    INFN/LNF, Frascati (Roma)
  • A. Bogomyagkov, I. Koop, E. B. Levichev, S. A. Nikitin, P. A. Piminov, D. N. Shatilov
    BINP SB RAS, Novosibirsk
  • G. Marchiori
    INFN-Pisa, Pisa
  • E. Paoloni
    University of Pisa and INFN, Pisa
  Submitted for the High Luminosity Study Group for an Asymmetric Super-B-Factory: Parameters are being studied for a high luminosity e+e- collider operating at the Upsilon 4S that would deliver a luminosity of 1 to 2 x 1036/cm2/s. This collider would use a novel combination of linear collider and storage ring techniques. In this scheme an electron beam and a positron beam are stored in low-emittance damping rings similar to those designed for a Linear Collider (LC) or the next generation light source. A LC style interaction region is included in the ring to produce sub-millimeter vertical beta functions at the collision point. A large crossing angle (±25 mrad) is used at the collision point to allow beam separation. A crab-waist scheme is used to reduce the hourglass effect and restore peak luminosity. Beam currents of about 1.8 A in 1400 bunches can produce a luminosity of 1036/cm2/s with upgrade possibilities. Design parameters and beam dynamics effects are discussed.  
 
WEPP040 New Low Emittance Lattices for the SuperB Accelerator Project emittance, sextupole, lattice, polarization 2608
 
  • M. E. Biagini, M. Boscolo, P. Raimondi, S. Tomassini, M. Zobov
    INFN/LNF, Frascati (Roma)
  • S. Bettoni
    CERN, Geneva
  • A. Bogomyagkov, I. Koop, E. B. Levichev, S. A. Nikitin, P. A. Piminov, D. N. Shatilov
    BINP SB RAS, Novosibirsk
  • E. Paoloni
    University of Pisa and INFN, Pisa
  • J. Seeman, M. K. Sullivan, U. Wienands, W. Wittmer
    SLAC, Menlo Park, California
  New low emittance lattices (1.6 nm at 7 GeV, 2.8 nm at 4 GeV) have been designed for the asymmetric SuperB accelerator aiming at a luminosity of 1036 cm-2 s-1. Main optics features are two alternating arc cells with different horizontal phase advance, in order to decrease beam emittance and allow at the same time for easy chromaticity correction in the arcs. Emittance can be further reduced by a factor of two for luminosity upgrade. New beam parameters have been chosen to fulfill the transparency conditions for 4x7 GeV beams, different from the asymmetric currents used in operating B-Factories. Beam polarization schemes have been studied and will be implemented in the lattice.  
 
WEPP042 An Improved Design for a SuperB Interaction Region quadrupole, emittance, interaction-region, background 2614
 
  • M. K. Sullivan, J. Seeman, U. Wienands
    SLAC, Menlo Park, California
  • S. Bettoni
    CERN, Geneva
  • M. E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma)
  • E. Paoloni
    University of Pisa and INFN, Pisa
  We present an improved design for a SuperB interaction region. The new design attempts to minimize the bending of the two colliding beams which results from shared magnetic elements near the Interaction Point (IP). The total crossing angle at the IP is increased from 34 mrad to 50 mrad and the distance from the IP to the first quadrupole is increased. Although the two beams still travel through this shared magnet, these changes allow for a new a new magnetic field design with a septum which gives the magnet two magnetic centers. This greatly reduces the beam bending from this shared quadrupole and thereby reduces the radiative bhabha background for the detector as well as any beam emittance growth from the bending. We decribe the new design for the interaction region.  
 
WEPP044 Commissioning the 90° Lattice for the PEP II High Energy Ring lattice, synchrotron, insertion, emittance 2617
 
  • W. Wittmer, Y. Cai, W. X. Cheng, W. S. Colocho, F.-J. Decker, S. Ecklund, A. S. Fisher, Y. Nosochkov, A. Novokhatski, M. K. Sullivan, U. Wienands, Y. T. Yan, G. Yocky
    SLAC, Menlo Park, California
  In order to benefit from further reduction of the vertical IP beta function of the PEP-II HER the bunch length should be reduced. This will be achieved by changing the phase advance from 60 deg to 90 deg in the four arcs not adjacent to the IR region, thus reducing momentum compaction by about 30% and reducing bunch length from a present 12 mm down to 8.5 mm at low beam current. In preparation to implement the 90 deg lattice the main HER quadrupole and sextupole strings and their power supplies have been reconfigured. Compared to the 60 deg lattice it was expected that dynamic aperture and injection will be more difficult. The synchrotron tune initially will be lower but can be brought back by raising the rf voltage. Beam emittance is held at 48 nmr by introducing a significant dispersion beat in the arcs. The lattice was successfully commissioned at currents up to 800mA in August 2007. In this paper we will compare the actual machine with the predicted behaviour, explain the correction strategies used and give an overall assessment of the operation and the benefit of the new lattice configuration.  
 
WEPP045 Suppression of Beam-beam Resonances in Crab Waist Collisions sextupole, resonance, betatron, collider 2620
 
  • M. Zobov, P. Raimondi
    INFN/LNF, Frascati (Roma)
  • D. N. Shatilov
    BINP SB RAS, Novosibirsk
  The recently proposed Crab Waist scheme of beam-beam collisions can substantially increase the collider luminosity since it combines several potentially advantageous ideas. One of the basic ingredients of the scheme is the use of dedicated sextupoles in the interaction region for the vertical beta function waist rotation at the interaction point. In this paper we show how this nonlinear focusing helps to suppress betatron and synchrobetatron resonances arising in beam-beam collisions due to particles’ vertical motion modulation by their horizontal oscillations.  
 
WEPP046 Final Focus for the Crab-waist Tau-charm Factory quadrupole, factory, interaction-region, collider 2623
 
  • I. N. Okunev
    BINP, Novosibirsk
  • A. Bogomyagkov, E. B. Levichev, P. A. Piminov, S. V. Sinyatkin, P. Vobly
    BINP SB RAS, Novosibirsk
  In the crab-waist colliders design of the final focus region is a matter of primary importance. The paper describes analysis of final focus quadrupole design and results of particles tracking through the quadrupoles.  
 
WEPP047 Optics Implications of Implementing Nb3Sn Magnets in the LHC Phase I Upgrade optics, quadrupole, focusing, lattice 2626
 
  • J. A. Johnstone, V. Kashikhin, N. V. Mokhov, A. V. Zlobin
    Fermilab, Batavia, Illinois
  CERN has encouraged the US-LARP collaboration to participate in Phase I of the LHC luminosity upgrade by analyzing the benefits gained by using Nb3Sn technology to replace the functionality of select magnets CERN is commited to construct using NbTi magnets. Early studies have shown that the much higher gradients (shorter magnetic lengths) and energy load of Nb3Sn magnets compared to their NbTi counterpars is very favorable – allowing the insertion of additional absorbers between Q1 & Q2, for example. This paper discusses the relative merits of the NbTi and Nb3Sn options.  
 
WEPP049 Advances on ELIC Design Studies electron, ion, optics, collider 2632
 
  • S. A. Bogacz, P. Chevtsov, Y. S. Derbenev, P. Evtushenko, M. Hutton, G. A. Krafft, R. Li, L. Merminga, J. Musson, B. C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
  • J. Qiang
    LBNL, Berkeley, California
  • H. K. Sayed
    Old Dominion University, Norfolk, Virginia
  An electron-ion collider of a center-of-mass energy up to 90 GeV at luminosity up to 1035 cm-2s-1 with both beams highly polarized is essential for exploring the new QCD frontier of strong color fields in nuclear and precisely imaging the sea-quarks and gluons in the nucleon. A conceptual design of a ring-ring collider based on CEBAF (ELIC) with energies up to 9 GeV for electrons/positrons and up to 225 GeV for protons and 100 GeV/u for ions has been proposed to fulfill the science desire and to serve as the next step for CEBAF after the planned 12 GeV energy upgrade of the fixed target program. Here, we summarize recent design progress for the ELIC complex with four interaction points (IP); including interaction region optics with chromatic aberration compensation scheme and complete lattices for the Figure-8 collider rings. Further optimization of crab crossing angles at the IPs, simulations of beam-beam interactions and electron polarization in the Figure-8 ring and its matching at the IPs are also discussed.  
 
WEPP051 QCD Explorer Based eA and γA Colliders collider, ion, electron, linac 2635
 
  • H. Karadeniz
    Turkish Atomic Energy Authority, Ankara
  • E. Recepoglu
    SNRTC, Ankara
  • S. Sultansoy
    TOBB ETU, Ankara
  TeV scale lepton-hadron and photon-hadron colliders are necessary both to clarify fundamental aspects of strong interactions and for adequate interpretation of the LHC data. Today, there are two realistic proposals for the post-HERA era, namely, QCD Explorer (QCD-E) and Large Hadron electron Collider (LHeC). Both QCD-E and LHeC can operate as eA colliders, whereas γp and γA options are unique for QCD-E. Another advantage of QCD-E is the possibility to increase the center of mass energy by lengthening of electron linac. In this presentation main parameters of the QCD-E nucleus options are discussed.  
 
WEPP071 Preliminary Exploratory Study of Different Phase II Collimators simulation, collimation, radiation, impedance 2683
 
  • L. Lari, R. W. Assmann, A. Bertarelli, C. Bracco, M. Brugger, F. Cerutti, A. Dallocchio, A. Ferrari, M. Mauri, S. Roesler, L. Sarchiapone, V. Vlachoudis
    CERN, Geneva
  • J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith
    SLAC, Menlo Park, California
  • L. Lari
    EPFL, Lausanne
  The LHC collimation system is installed and commissioned in different phases, following the natural evolution of the LHC performance. To improve cleaning efficiency towards the end of the low beta squeeze at 7TeV, and in stable physics conditions, it is foreseen to complement the 30 highly robust Phase I secondary collimators with low impedance Phase II collimators. At this stage, their design is not yet finalized. Possible options include metallic collimators, graphite jaws with a movable metallic foil, or collimators with metallic rotating jaws. As part of the evaluation of the different designs, the FLUKA Monte Carlo code is extensively used for calculating energy deposition and studying material damage and activation. This report outlines the simulation approach and defines the critical quantities involved.  
 
WEPP097 Simulation of Wakefield Effect in ILC IR Chamber simulation, impedance, linac, collider 2743
 
  • S. Pei, T. O. Raubenheimer, A. Seryi, J. C. Smith
    SLAC, Menlo Park, California
  To achieve super high luminosity, high current beams with very short bunch length are needed, which carry high intensity EM fields. For ILC, two bunch trains with bunch length of 300μm and bunch charge of 3.2nC are needed to collide at the IR to achieve the ILC luminosity goals. When the 300μm bunches pass through the IR chamber, wakefields will be excited, which will cause HOM power flowing through the IR chamber beam pipe to the final doublets due to the high frequency characteristic of the induced wakefields. Since superconducting technology is adopted for the final doublets of ILC BDS, whose operation stability might be affected by the HOM power produced at the IR chamber, quench might happen. In this paper, we did some analytical estimation and numerical simulation on the wakefield effects in ILC IR chamber.  
 
WEPP154 Linac-LHC ep Collider Options linac, proton, electron, emittance 2847
 
  • F. Zimmermann, F. Bordry, H.-H. Braun, O. S. Brüning, H. Burkhardt, R. Garoby, T. P.R. Linnecar, K. H. Mess, J. A. Osborne, L. Rinolfi, D. Schulte, R. Tomas, J. Tuckmantel, A. de Roeck
    CERN, Geneva
  • H. Aksakal
    N. U, Nigde
  • S. Chattopadhyay
    Cockcroft Institute, Warrington, Cheshire
  • A. K. Ciftci
    Ankara University, Faculty of Sciences, Tandogan/Ankara
  • J. B. Dainton
    Liverpool University, Science Faculty, Liverpool
  • A. Eide
    EPFL, Lausanne
  • B. J. Holzer
    DESY, Hamburg
  • M. Klein
    University of Liverpool, Liverpool
  • S. Sultansoy
    TOBB ETU, Ankara
  • A. Vivoli
    LAL, Orsay
  • F. J. Willeke
    BNL, Upton, New York
  We describe various parameter scenarios for a ring-linac ep collider based on LHC and an independent s.c. electron linac. Luminosities of order 1032/cm2/s can be achieved with a standard ILC-like linac, operated either in pulsed or cw mode, with acceptable beam power. Reaching much higher luminosities, up to 1034/cm2/s and beyond, would require the use of two linacs and the implementation of energy recovery. Advantages and challenges of a ring-linac ep collider vis-a-vis an alternative ring-ring collider are discussed.  
 
THYG02 Results from the CLIC Test Facility CTF3 and Update on the CLIC Design linac, acceleration, electron, beam-loading 2912
 
  • G. Geschonke
    CERN, Geneva
  The CLIC Test Facility CTF3 is being built and commissioned in stages. Up to now the facility consists of an electron linac, a magnetic chicane for changing bunch length, the Delay Loop and the Combiner Ring. Recent experience and commissioning results will be presented together with plans for the next steps which should lead to feasibility demonstration of CLIC technology by the year 2010. The CLIC design has been reviewed in detail. The resulting changes in parameters will be presented.  
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THYG03 Ionization Cooling and Muon Colliders collider, emittance, factory, dipole 2917
 
  • R. P. Johnson
    Muons, Inc, Batavia
  Recent developments in the field of muon beam cooling are reviewed. A view of the impact of new cooling concepts on the overall design of muon colliders is included, as are the prospects for the experimental verification of the required muon beam cooling concepts and technology.  
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THPC021 Investigations on a Q0 Doublet Optics for the LHC Luminosity Upgrade quadrupole, optics, closed-orbit, alignment 3023
 
  • E. Laface, W. Scandale, E. Y. Wildner
    CERN, Geneva
  • C. Santoni
    Université Blaise Pascal, Clermont-Ferrand
  The Q0 scheme of the LHC insertion region is based on the introduction of a doublet of quadrupoles at 13 meters from IP. We present here the doublet optics and the magnets layout such as gradients, lengths, positions and apertures. In this scheme we show the gain in luminosity and chromaticity, with respect to a nominal layout with β*=0.25 (i.e. LHC phase 1 upgrade) and β*=0.15 m, due to a smaller beta-max. We show the alignment tolerance and the energy deposition issues, in Q0A-Q0B. We also consider shielding the magnets with liners. The capability of Q0 optics to limit the β function could be exploited after the LHC Phase 1 upgrade in order to reduce the β* below 0.25 m, leaving the upgraded triplet unchanged.  
 
THPC059 Studies of Wire Compensation and Beam-beam Interaction in RHIC simulation, emittance, dynamic-aperture, beam-losses 3119
 
  • H. J. Kim, T. Sen
    Fermilab, Batavia, Illinois
  • N. P. Abreu, W. Fischer
    BNL, Upton, Long Island, New York
  Beam-beam interaction is one of the dominant source of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and the principle is now being experimentally investigated at RHIC. In this paper, we use simulations to study the effectiveness of wire compensation based on tune footprints, diffusive apertures, and beam loss rates using a parallel weak-strong beam simulation code (BBSIM). In addition we extensively study the diffusion properties of RHIC beams for different beam and wire parameters. Beam-beam effects on emittance growth are investigated through the solution of the diffusion equation for the transverse action variables.  
 
THPC144 A Beam Quality Monitor for LHC Beams in the SPS extraction, dipole, injection, pick-up 3324
 
  • G. Papotti
    CERN, Geneva
  The SPS Beam Quality Monitor (BQM) system monitors the longitudinal parameters of the beam before extraction to the LHC to prevent losses and degradation of the LHC luminosity by the injection of low quality beams. It is implemented in two priority levels. The highest level is related to machine protection, e.g. verifying SPS-LHC synchronization and global beam structure. If the specifications are not met, the beam is dumped in the SPS before extraction. On the second level, individual bunch position, length and stability are checked for beam quality assessment. Tolerances are adapted to the mode of operation and extraction to the LHC can also be inhibited. Beam parameters are accessed by acquiring bunch profiles with a longitudinal pick up and fast digital oscilloscope. The beam is monitored for instabilities during the acceleration cycle and thoroughly checked a few ms before extraction for a final decision on extraction interlock. Dedicated hardware and software components implementing fast algorithms are required. In this paper the fast algorithms and their possible implementations are presented.  
 
THPP055 Stochastic Cooling Developments for the HESR at FAIR target, antiproton, lattice, simulation 3491
 
  • H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen
    FZJ, Jülich
  • T. Katayama
    CNS, Saitama
  • L. Thorndahl
    CERN, Geneva
  The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt will be built as an anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An important and challenging feature of the new facility is the combination of phase space cooled beams with internal targets. In addition to electron cooling transverse and longitudinal stochastic cooling are envisaged to accomplish these goals. A detailed numerical analysis of the Fokker-Planck equation for longitudinal filter cooling including an internal target and intrabeam scattering has been carried out to demonstrate the stochastic cooling capability in the newly designed normal conducting ring lattice of the HESR. Theoretical predictions have been compared to experimental cooling results with internal targets at the COSY facility. Recent developments for the HESR stochastic cooling equipment will be discussed. The design of new high sensitive printed loop couplers and ring slot couplers for the (2-4) GHz range as well as prototype measurements with protons in the COSY accelerator will be presented.  
 
FRXAGM01 RHIC and its Upgrade Programs polarization, electron, proton, ion 3723
 
  • T. Roser
    BNL, Upton, Long Island, New York
  As the first hadron accelerator and collider consisting of two independent superconducting rings RHIC has operated with a wide range of beam energies and particle species. After a brief review of the achieved performance the presentation will give an overview of the plans, challenges and status of machine upgrades, that range from a new heavy ion pre-injector and beam cooling at 100 GeV to a high luminosity electron-ion collider.  
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FRYAGM01 Upgrade Issues for the CERN Accelerator Complex proton, linac, injection, synchrotron 3734
 
  • R. Garoby
    CERN, Geneva
  The Large Hadron Collider at CERN is at a very advanced stage of construction and the first beam collisions in the experiments are expected during the year 2008. Work has now started for maximizing its physics reach and for preparing for other foreseeable needs. Beyond upgrades in the LHC itself, mainly in the optics of the insertions, the injector complex has to be renewed to deliver beam with upgraded characteristics with a high reliability. In a first phase, a new 160 MeV H- linac (“Linac4”) will be built to replace the present 50 MeV proton linac (Linac2) and extensive consolidation will be made. In a second phase, the present 26 GeV PS and its set of injectors (Linac2 + PSB) are planned to be replaced with a ~50 GeV synchrotron (“PS2”) using a 4 GeV superconducting proton linac (“SPL”) as injector. The SPS itself will also be the subject of major improvements, to be able to cope with a 50 GeV injection energy and with beams of much higher brightness. These proposals are described as well as their potential to evolve and fit the needs of future facilities for radioactive ions and/or neutrinos.  
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