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luminosity

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MOYKI01 e+e- Factories factory, storage-ring, vacuum, electron 12
 
  • M. K. Sullivan
  Funding: Work supported by USDOE contract DE-AC02-76SF00515

The achievements of the e+e- Factories have been impressive. The KEK B- Factory has achieved a peak luminosity of 1.7x1034 cm2/s and the PEP-II B-Factory has reached 1.2x1034 cm2/s while the Dafne Phi-Factory has obtained 1.5x1032 cm2/s. Early in the B-Factory running, CP violation in the B meson system was found to be consistent with the prediction of the Standard Model. Now all three factories are integrating as much luminosity as they can in order to look for rare decay channels that may have a rate that differs from the value predicted by the Standard Model and therefore hint at New Physics. I will give a status report on the most recent accomplishments of all three factories PEP-II, KEKB and Dafne and will show what the three facilities have for plans to further improve performance.

 
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MOZAKI01 Compensation of the Crossing Angle with Crab Cavities at KEKB coupling, emittance, resonance, factory 27
 
  • K. Oide
  • T. Abe, K. Akai, M. Akemoto, A. Akiyama, A. Arinaga, K. Ebihara, K. Egawa, A. Enomoto, J. W. Flanagan, S. Fukuda, H. Fukuma, Y. Funakoshi, K. Furukawa, T. Furuya, K. Hara, T. Higo, S. Hiramatsu, H. Hisamatsu, H. Honma, K. Hosoyama, T. Ieiri, N. Iida, H. Ikeda, M. Ikeda, S. Isagawa, H. Ishii, A. Kabe, E. Kadokura, T. Kageyama, K. Kakihara, E. Kako, S. Kamada, T. Kamitani, K.-I. Kanazawa, H. Katagiri, S. Kato, T. Kawamoto, S. Kazakov, M. Kikuchi, E. Kikutani, K. Kitagawa, H. Koiso, Y. Kojima, K. Komada, T. Kubo, K. Kudo, N. K. Kudo, K. Marutsuka, M. Masuzawa, S. Matsumoto, T. Matsumoto, S. Michizono, K. Mikawa, T. Mimashi, S. Mitsunobu, K. Mori, A. Morita, Y. Morita, H. Nakai, H. Nakajima, T. T. Nakamura, H. Nakanishi, K. Nakao, S. Ninomiya, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, Y. Ohsawa, N. Ohuchi, M. Ono, T. Ozaki, K. Saito, H. Sakai, Y. Sakamoto, M. Sato, M. Satoh, K. Shibata, T. Shidara, M. Shirai, A. Shirakawa, T. Sueno, M. Suetake, Y. Suetsugu, R. Sugahara, T. Sugimura, T. Suwada, O. Tajima, S. Takano, S. Takasaki, T. Takenaka, Y. Takeuchi, M. Tawada, M. Tejima, M. Tobiyama, N. Tokuda, S. Uehara, S. Uno, Y. Yamamoto, Y. Yano, K. Yokoyama, Ma. Yoshida, M. Yoshida, S. I. Yoshimoto, K. Yoshino
    KEK, Ibaraki
  • E. Perevedentsev, D. N. Shatilov
    BINP SB RAS, Novosibirsk
  The crab cavities are presently being installed in the KEKB rings to compensate the crossing angle at collision and thus increase luminosity. This will be the first experience with such cavities in colliders. Results on the beam operation of the new cavities, both for single and colliding beams, will be presented including the luminosity performance and limitations.

Work presented on behalf of the KEKB Accelerator Group.

 
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MOZAKI02 New Developments in Super B Factories damping, collider, emittance, injection 32
 
  • P. Raimondi
  The design of a super B factory with luminosity in the range of 1036 cm-2 sec-1, based on innovative ideas like the crabbed waist, is being studied by an international collaboration, in close contact with the ILC studies.  
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MOZAKI03 PEP-II at 1.2·1034/cm2/s Luminosity kicker, emittance, vacuum, lattice 37
 
  • J. Seeman
  • Y. Cai, M. K. Sullivan, U. Wienands
    SLAC, Menlo Park, California
  Funding: Work supported by US DOE contract DE-AC02-76SF00515.

For the PEP-II Operation Staff: PEP-II is an asymmetric e+e- collider operating at the Upsilon 4S and has recently set several performance records. The luminosity has reached 1.2x1034/cm2/s and has delivered an integrated luminosity of 910/pb in one day. PEP-II operates in continuous injection mode for both beams boosting the integrated luminosity. The peak positron current has reached 3.0 A of positrons and 1.9 A of electrons in 1732 bunches. The total integrated luminosity since turn on in 1999 has reached over 410/fb. This paper reviews the present performance issues of PEP-II and also the planned increase of luminosity in the near future to over 2 x 1034/cm2/s.

 
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MOZBKI01 CESR-C: A Wiggler-Dominated Collider wiggler, optics, damping, electron 48
 
  • D. H. Rice
  Funding: Work supported by US National Science Foundation grant PHY-0202078

CESR-c operates with twelve 2.1 Tesla wigglers that account for 90% of the synchrotron radiation with beam energy in the range of 1.8 to 2.1 GeV. The wigglers reduce the radiation damping time from 0.5 seconds to 50 milliseconds. The carefully designed wigglers restrict neither physical nor dynamic aperture of the storage ring, though both quadrupole and sextupole distributions must be tailored to compensate the primary optics effects of the wigglers. Colliding beam performance limits are determined by the numerous parasitic beam-beam interactions in the single ring. Several approaches taken to mitigate these limiting effects are described herein. The CESR-c wigglers are an excellent match to the requirements for future damping rings. We describe how with flexible optics, extensive infrastructure, and resource expertise, they form an effective test bed for assessment and solution of damping ring issues such as electron cloud and ion effects, and achieving ultra-low emittance beams.

 
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MOZBKI02 The BEPC II: Status and Early Commissioning injection, linac, electron, quadrupole 53
 
  • J. Q. Wang
  • L. Ma, C. Zhang
    IHEP Beijing, Beijing
  BEPCII is the upgrade project of Beijing Electron Positron Collider (BEPC). The installation of its storage ring components except the superconducting (SC) insertion magnets was completed in early November, 2006. While the improvement of the cryogenic system for SC magnets is in progress, the commissioning of the synchrotron radiation (SR) mode for the so called back-up scheme with conventional magnets adopted in the interaction region (IR), started on Nov. 13, 2006. The first electron beam was stored on Nov. 18 and later beam was provided to SR users for about 1 month starting from Dec. 25, 2006. The commissioning of the collision mode including the electron and positrion rings started in Feb. 2007. The first beam collision was realized on Mar. 25. Then optimization of the beam parameters was done. On May 14, a 100mA to 100mA beam collision was achieved with 20 bunches for each beam. The luminosity estimated from the measured beam-beam parameters has reached that of BEPC. From May 25 the machine turns to the second run of the SR mode. This paper provides an overview of the construction and introduce the commissioning results of the backup scheme of BEPCII.  
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MOOBKI01 Central Mass Energy Determination in High Precision Experiments on VEPP-4M electron, positron, energy-calibration, sextupole 63
 
  • A. Bogomyagkov
  • S. A. Nikitin, I. B. Nikolaev, A. G. Shamov, A. N. Skrinsky, G. M. Tumaikin
    BINP SB RAS, Novosibirsk
  The series of experiments on mass measurements of J/Psi, Psi' and Psi'' mesons have been done on VEPP-4M collider. The accuracy of obtained mass values for JΨ- and Psi'- mesons exceeded more than 3 times the world values, based on experiments on VEPP-4* and E760**. The ongoing experiment on tau lepton mass measurement is expected to achieve accuracy 1.5-2 times better than the present world value. The present paper describes the process and uncertainties of luminosity weighted interaction energy definition. The errors of interaction energy include uncertainties due to beam energy calibration by resonant depolarization technique and errors of interaction energy calculation.

* A. A. Zholentz et al., Phys. Lett. B 96 (1980) 214-216.** T. A. Armstrong et al., Phys. Rev. D47 (1993) 772-783.

 
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MOOBKI02 DAΦ NE Phi-Factory Upgrade for Siddharta Run sextupole, dynamic-aperture, resonance, injection 66
 
  • M. E. Biagini
  • D. Alesini, D. Babusci, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, G. Di Pirro, A. Drago, A. Gallo, S. Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, C. Milardi, F. Murtas, L. Pellegrino, M. A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, G. Sensolini, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov
    INFN/LNF, Frascati (Roma)
  • S. Bettoni
    CERN, Geneva
  • I. Koop, E. Levichev, P. A. Piminov, D. N. Shatilov, V. V. Smaluk
    BINP SB RAS, Novosibirsk
  • K. Ohmi
    KEK, Ibaraki
  An upgrade of the DAΦNE Phi-Factory at LNF is foreseen in view of the installation of the Siddharta detector in 2007. A new Interaction Region suitable to test the large crossing angle and crabbed waist collision schemes* will be installed. Other machine improvements, such as wigglers modifications, new injection kickers and chambers coating will be realized with the goal of reaching luminosity of the order of 1033/cm2/s. The principle of operation of the new scheme, together with hardware designs and simulation studies, will be presented.

*DAPHNE Upgrade Team, "DAPHNE Upgrade for Siddharta run", DAPHNE Tech. Note G-68, LNF-INFN, Dec. 2006

 
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MOPAN018 Performance of the New Coupled Bunch Feedback System at HERA-p feedback, controls, kicker, diagnostics 185
 
  • M. G. Hoffmann
  • S. Choroba, F. Eints, U. Hurdelbrink, P. Morozov, Y. Nechaev, J. Randhahn, S. Ruzin, S. Simrock, V. Soloviev
    DESY, Hamburg
  A longitudinal broadband damper system to control coupled bunch instabilities (LMBF) has been installed in the 920~GeV proton accelereator HERA-p at the Deutsches Elektronen-Synchrotron DESY in Q4/2005. The Feedback system was fully automated, in order to relieve the operator from manual control during system operation. During comissioning in Q1/2006 it turned out that the performance goals were reached and the noise is not as much a problem as expected. The proton bunch length is significantly reduced as is the stretching of the bunches over runtime. Without additional damping the bunch length is about 1.5~ns (FWHM) at the beginning of a typical luminosity run. With the new feedback system in operation the bunch length could be decreased to 1.0 ns at best. Although the bunches get longer during the luminosity run, the integrated luminosity gain is thus up to 5%. System optimization points were found in automatic gain adjustment during acceleration ramp, oscillation level triggering and timing of kicker pulse to bunch. We describe the commissioning of the multibunch feedback system and the adjustment procedures. A performace overview after one year of operation is given.  
 
MOPAN066 First Tests of a Precision Beam Phase Measurement System in CTF3 linac, pick-up, extraction, collider 302
 
  • A. Andersson
  • J. P.H. Sladen
    CERN, Geneva
  Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme -Structuring the European Research Area-, contract number RIDS-011899.

High precision beam phase measurements will be vital for synchronization of main and drive beams in CLIC. Development work is underway with the aim to demonstrate 0.1 degree resolution for a wideband 30GHz measurement. In order to be able to test this with a beam exhibiting much higher phase jitter, two prototypes have been built so that the difference in their outputs can be measured. Results of measurements made with bunch trains in CTF3 are presented.

 
 
MOPAN073 Parametric Study of Heat Deposition from Collision Debris into the Insertion Superconducting Magnets for the LHC Luminosity Upgrade insertion, quadrupole, target, superconducting-magnet 323
 
  • C. Hoa
  • F. Broggi
    INFN/LASA, Segrate (MI)
  • F. Cerutti, J.-P. Koutchouk, G. Sterbini, E. Y. Wildner
    CERN, Geneva
  With a new geometry in a higher luminosity environment, the power deposition in the superconducting magnets becomes a critical aspect to analyze and to integrate in the insertion design. In this paper, we quantify the power deposited in magnets insertion at variable positions from the interaction point (IP). A fine characterization of the debris due to the proton-proton collisions at 7 TeV, shows that the energetic particles in the very forward direction give rise to non intuitive dependences of the impacting energy on the magnet front face and inner surface. The power deposition does not vary significantly with the distance to the interaction point, because of counterbalancing effects of different contributions to power deposition. We have found out that peak power density in the magnet insertion does not vary significantly with or without the Target Absorber Secondaries (TAS) protection.  
 
MOPAN083 130 mm Aperture Quadrupoles for the LHC Luminosity Upgrade quadrupole, dipole, optics, magnet-design 350
 
  • E. Todesco
  • F. Borgnolutti
    CERN, Geneva
  • A. Mailfert
    ENSEM, Vandoeuvre les Nancy
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395)

Studies for the LHC luminosity upgrade showed the need for quadrupoles with apertures much larger than the present baseline (70 mm). In this paper we focus on the design issues of a 130 mm aperture quadrupole. We first consider the Nb-Ti option, presenting the magnetic design with the LHC dipole cable. We study the Lorentz forces and we discuss the field quality constraints. For the Nb3Sn option we sketch two designs, the first based on the LARP 10 mm cable, and the second one on a 15 mm cable. The issue of the stress induced by the Lorentz forces, which is critical for the Nb3Sn, is discussed using both scaling laws and finite element models.

 
 
MOPAN084 Estimating Field Quality in Low-beta Superconducting Quadrupoles and its Impact on Beam Stability quadrupole, multipole, collider, superconducting-magnet 353
 
  • E. Todesco
  • B. Bellesia, J.-P. Koutchouk
    CERN, Geneva
  • C. Santoni
    Universite Blaise Pascal, Clermont-Ferrand
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395)

The aim of this analysis is to study if the field quality in a large aperture low-beta superconducting quadrupole for the LHC upgrade limits the beam performances due to increased geometric aberrations. Random field errors in superconducting quadrupoles are usually estimated by computing the effect of a random positioning of the coil blocks around the nominal position with an r.m.s. of 0.05 mm. Here, we review the experience acquired in the construction of 7 superconducting quadrupoles in the RHIC and in the LHC projects to estimate the precision in the block positioning, showing that there is no visible dependence on the magnet aperture. Different magnet models are then used to estimate the expected field quality in quadrupoles with apertures ranging from 50 to 200 mm. The impact on geometrical aberrations and scaling laws for their dependence on the aperture are finally evaluated.

 
 
MOPAN118 High Field HTS Solenoid for Muon Cooling collider, emittance, simulation, magnet-design 446
 
  • S. A. Kahn
  • M. Alsharo'a, R. P. Johnson, M. Kuchnir
    Muons, Inc, Batavia
  • R. C. Gupta, R. B. Palmer, P. Wanderer, E. Willen
    BNL, Upton, Long Island, New York
  • D. J. Summers
    UMiss, University, Mississippi
  Funding: Work supported by U. S. Department of Energy under Contract DE-AC02-98CH1088 and SBIR Grant DE-FG02-04ER86191

The ability of high temperature superconducting (HTS) conductor to carry high currents at low temperatures makes feasible the development of very high field magnets for uses in accelerators and beam-lines. A specific application of a very high field solenoid is to provide a very small beta region for the final cooling stages for a muon collider. This paper will describe a conceptual design of a 50 Tesla solenoid based on Bi-2223 HTS tape, where the magnet will be operated at 4.2 K to take advantage of the high current carrying capacity at that temperature. A 25 Tesla solenoid has been run using a 5 Tesla Bi-2212 insert. The current carrying capacity of the BSCCO wire has been measured to be 266 Amps/mm2 at 4.2 K at the NHFML. This paper will describe the technical issues associated with building this 50 Tesla magnet. In particular it will address how to mitigate the large Lorentz stresses associated with the high field magnet and how to design the magnet to reduce the compressive end forces.

 
 
MOPAS011 Uniform Longitudinal Beam Profiles in the Fermilab Recycler Using Adaptive RF Correction antiproton, extraction, controls, injection 458
 
  • M. Hu
  • D. R. Broemmelsiek, B. Chase, J. L. Crisp, N. E. Eddy, P. W. Joireman, K. Y. Ng
    Fermilab, Batavia, Illinois
  Non-uniformity in longitudinal beam profiles due to potential well distortion have been observed in the Fermilab Recycler Ring. The main source of distortion, the analysis, and the experimental verification of a solution are presented. An adaptive algorithm has been developed to remove the distortion. This algorithm has been implemented in a custom FPGA-based module, which has been integrated into the current Low Level RF system.  
 
MOPAS013 Design Study of a 2-in-1 Large-aperture IR Dipole (D2) for the LHC Luminosity Upgrade dynamic-aperture, quadrupole, magnet-design, dipole 464
 
  • V. Kashikhin
  • A. V. Zlobin
    Fermilab, Batavia, Illinois
  Funding: This work was supported by the U. S. Department of Energy.

After LHC operates for several years at nominal parameters it will need an upgrade to higher luminosity. Replacing the low-beta insertions with a higher performance design based on advanced superconducting magnets is a straightforward step in this direction. One of the approaches being considered for the new LHC IRs is a "dipole-first: option with two separation dipoles placed in front of the focusing quadrupoles. It reduces the number of parasitic collisions with respect to the "quadrupole-first" option and allows independent field error corrections for each beam. Most of key magnet designs for the "dipole-first" option including high-field large-aperture dipoles (D1) and 2-in-1 quadrupoles have already been studied and reported. This paper focuses on design studies of the 2-in-1 separation dipole (D2) located between D1 and the quadrupoles. High operation field of the same polarity in large adjacent apertures imposes limitations on the maximum field, field quality and mechanics for this magnet. This paper analyses possible D2 magnet designs based on Nb3Sn superconductor and compares them in terms of the aperture size, maximum field, field quality and Lorents forces in the coil.

 
 
MOPAS027 Energy Deposition Studies of Block-Coil Quadrupoles for the LHC Luminosity Upgrade quadrupole, radiation, interaction-region, cryogenics 491
 
  • N. V. Mokhov
  • P. Ferracin, G. L. Sabbi
    LBNL, Berkeley, California
  • V. Kashikhin, M. Monville
    Fermilab, Batavia, Illinois
  Funding: Work supported by the Director, Office of Science, U. S. Department of Energy under Contract DE-AC02-05CH11231.

At the LHC upgrade luminosity of 1035 cm-2 s-1, collision product power in excess of a kW is deposited in the inner triplet quadrupoles. The quadrupole field sweeps secondary particles from pp-collisions into the superconducting coils, concentrating the power deposition at the magnetic mid-planes. The local peak power density can substantially exceed the conductor quench limits and reduce component lifetime. Under these conditions, block-coil geometries may result in overall improved performance by removing the superconductor from the magnetic mid-planes and/or allowing increased shielding at such locations. First realistic energy deposition simulations are performed for an interaction region based on block-coil quadrupoles with parameters suitable for the LHC upgrade. Results are presented on 3-D distributions of power density and accumulated dose in the inner triplet components as well as on dynamic heat loads on the cryogenic system. Optimization studies are performed on configuration and parameters of the beam pipe, cold bore and cooling channels. The feasibility of the proposed design is discussed.

 
 
MOPAS064 Radioactivity and Damage Studies for Next Generation Colliders radioactivity, collider, gun, radiation 578
 
  • J. E. Spencer
  Funding: Work supported by U. S. Dept. of Energy contract DE-AC02-76SF00515.

We consider optimization of the generalized luminosity per unit cost of a linear collider in this ES&H era. Examples running over the length of the LC, starting at the source and ending at the dump, suggest that both costs (capital and operating) and environmental issues can be improved in a compatible way. Thus, a RoHS by any other name (WEES or OSHA) need not present thorny problems requiring unexpected R&D but a push to leverage many recent advances that might otherwise be overlooked or avoided. The physics is interesting and the true amortized cost may be seriously underestimated by ignoring such issues. For example, the entire, interior surface of a laser driven RF gun involves interesting materials science where the space requires continuous UHV to sustain stable, acceptable quantum efficiency as well as avoid RF breakdown damage in an environment that is also subject to radiation damage. All of these can seriously reduce a gun's output and LCs luminosity. Intelligent design of rad-hard systems can approach the ideal of bug-proof software that needn't produce overly slow or ponderous systems while providing opportunities to innovate that justify the costs.

 
 
TUZAKI01 RHIC Plans Towards Higher Luminosity electron, ion, proton, heavy-ion 709
 
  • A. V. Fedotov
  Funding: Work supported by the U. S. Department of Energy under contract No. DE-AC02-98CH10886.

The Relativistic Heavy Ion Collider (RHIC) is designed to provide luminosity over a wide range of beam energies and species, including heavy ions, polarized protons, and asymmetric beam collisions. In the first seven years of operation there has been a rapid increase in the achieved peak and average luminosity, substantially exceeding design values. Work is presently underway to achieve the Enhanced Design parameters in about 2008. Planned major upgrades include the Electron Beam Ion Source (EBIS), the RHIC-II electron cooling upgrade, and construction of an electron-ion collider (eRHIC). We review the expected RHIC upgrade performance. Electron cooling and its impact on the luminosity at various collision energies both for heavy ions and protons are discussed in detail.

 
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TUZAKI02 LHC Upgrade Scenarios quadrupole, dipole, interaction-region, hadron 714
 
  • F. Zimmermann
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395)

The EU CARE-HHH and US-LARP programmes for an LHC upgrade aim at increasing the LHC luminosity by a factor of 10 around the year 2015. The upgrade plan envisages rebuilding the interaction regions (IRs) and modifying the beam parameters. In addition to advanced low-beta quadrupoles, the future IRs may accommodate other novel elements such slim s.c. dipoles or quadrupoles embedded deep inside the detectors, global low-angle crab cavities, and wire compensators of long-range beam-beam effects. Important constraints on the upgrade path are the maximum acceptable number of detector pile-up events, favoring many closely spaced bunches, and the heat load on the cold-magnet beam screens, pointing towards fewer and more intense bunches. In addition, the upgrade of the LHC ring proper should be complemented by an upgrade of the injector complex. I will present preferred luminosity upgrade scenarios for the LHC IRs and beam parameters, sketch accompanying injector enhancements, and comment on a longer-term LHC energy upgrade.

 
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TUOCKI01 Review of Recent Tevatron Operations antiproton, proton, beam-beam-effects, electron 719
 
  • R. S. Moore
  Fermilab's Tevatron proton-antiproton collider continues to improve its luminosity performance at the energy frontier root(s) = 1.96 TeV. The recent Tevatron operation will be reviewed and notable tasks leading to advancements will be highlighted. The topics to be covered include: work performed during the 14-week shutdown in 2006, improved helical orbits, automatic orbit stabilization during high-energy physics (HEP) stores, optics corrections, improvements in the quench protection system, and avenues to maximizing the integrated luminosity delivered to the CDF and D0 experiments.  
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TUOCKI02 Summary of the RHIC Performance during the FY07 Heavy Ion Run ion, proton, injection, beam-losses 722
 
  • K. A. Drees
  • 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, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, W. Fischer, W. Fu, G. Ganetis, J. Glenn, M. Harvey, T. Hayes, H.-C. Hseuh, H. Huang, J. Kewisch, R. C. Lee, V. Litvinenko, Y. Luo, W. W. MacKay, G. J. Marr, A. Marusic, R. J. Michnoff, C. Montag, J. Morris, B. Oerter, F. C. Pilat, V. Ptitsyn, T. Roser, J. Sandberg, T. Satogata, C. Schultheiss, F. Severino, K. Smith, S. Tepikian, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, S. Y. Zhang
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract Number DE-AC02-98CH10886 under the auspices of the US Department of Energy.

After the last successful RHIC Au-Au run in 2004 (Run-4), RHIC experiments now require significantly enhanced luminosity to study very rare events in heavy ion collisions. RHIC has demonstrated its capability to operate routinely above its design average luminosity per store of 2x1026 cm-2 s-1. In Run-4 we already achieved 2.5 times the design luminosity in RHIC. This luminosity was achieved with only 40% of bunches filled, and with β* = 1 m. However, the goal is to reach 4 times the design luminosity, 8x1026 cm-2 s-1, by reducing the beta* value and increasing the number of bunches to the accelerator maximum of 111. In addition, the average time in store should be increased by a factor of 1.1 to about 60% of calendar time. We present an overview of the changes that increased the instantaneous luminosity and luminosity lifetime, raised the reliability, and improved the operational efficiency of RHIC Au-Au operations during Run-7.

 
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TUOCKI03 Observations and Modeling of Beam-Beam Effects at the Tevatron Collider proton, antiproton, beam-beam-effects, collider 725
 
  • A. Valishev
  • Y. Alexahin, V. A. Lebedev, R. S. Moore, V. D. Shiltsev
    Fermilab, Batavia, Illinois
  This report summarizes recent experience with beam-beam effects at the Tevatron collider. Improvements in the beam life time resulting from implementation of the new helical orbit are analyzed. Effects of second order chromaticity correction and beam-beam compensation with Electron Lenses are studied.  
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TUOCKI04 Experimental Demonstration of Beam-Beam Compensation by Tevatron Electron Lenses and Prospects for the LHC electron, proton, collider, beam-beam-effects 728
 
  • V. D. Shiltsev
  • Y. Alexahin, V. Kamerdzhiev, G. F. Kuznetsov, X. Zhang
    Fermilab, Batavia, Illinois
  • K. Bishofberger
    LANL, Los Alamos, New Mexico
  We report the first experimental demonstration of compensation of beam-beam interaction effects with use of electron beams. Long-range and head-on interactions of high intensity proton and antiproton beams have been dominating sources of beam loss and lifetime limitations in the Tevatron in Collider Run II (2001-present). Electron lense acting on proton bunches has doubled their lifetime by compensating beam-beam interaction with antiprotons. We present results of the experiments, operational details and discuss possibilities of using electron lenses for beam-beam compensation in LHC.  
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TUPMS092 GdfidL Simulations of Non-Linear Tapers for ILC Collimators simulation, impedance, emittance, insertion 1380
 
  • J. D.A. Smith
  This paper summarises the GdfidL simulations relating to non-linear collimators, which offer the potential for improved wakefield performance at the ILC. Such collimators provide a further method for understanding the performance of simulation software in this challenging regime. Our results are compared with data from ESA at SLAC.  
 
TUPAN027 A New Complementary-Scan Technique for Precise Measurements of Resonance Parameters in Antiproton-Proton Annihilations resonance, antiproton, background, pick-up 1448
 
  • G. Stancari
  A new technique for precision measurements of resonance widths in antiproton-proton annihilations is presented. It is based on the analysis of excitation curves obtained by scanning the resonance twice, at constant orbit and at constant magnetic bend field, in an antiproton storage ring. The technique relies on precise revolution-frequency and orbit-length measurements, while making the results almost independent of the machine's phase-slip factor. The uncertainty is dominated by event statistics. The technique was recently applied by Fermilab Experiment E835 at the Antiproton Accumulator to obtain the most precise measurements to date of the total and partial widths of the psi(2S) charmonium meson. Future applications may include the PANDA experiment at the FAIR facility in Darmstadt.

On behalf of the Fermilab E835 Collaboration

 
 
TUPAN033 DAΦ NE Setup and Performances During the Second FINUDA Run collider, injection, coupling, wiggler 1457
 
  • C. Milardi
  • D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, P. Iorio, C. Ligi, F. Marcellini, C. Marchetti, 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)
  • J. D. Fox, D. Teytelman
    SLAC, Menlo Park, California
  • E. Levichev, S. A. Nikitin, P. A. Piminov, D. N. Shatilov
    BINP SB RAS, Novosibirsk
  Beam operations on DAΦNE restarted on October 2006 after a four months shut-down to remove the KLOE experimental detector and to install the FINUDA one. This period has been also used for maintenance and implementation of several upgrades. In the first two months of operation the peak and integrated luminosity already exceeds the values obtained during the first FINUDA run by 20%. The DAΦNE goal is to deliver 1 fb-1 integrated luminosity by the end of May 2007. The collider performances during the run are presented together with the improvements obtained in terms of ring nonlinearities and beam dynamics coming from several collider modifications.  
 
TUPAN034 Super-B Factory using Low Emittance Storage Rings and Large Crossing Angle collider, interaction-region, factory, injection 1460
 
  • J. Seeman
  • M. E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma)
  • Y. Cai, M. K. Sullivan, U. Wienands
    SLAC, Menlo Park, California
  Funding: Work supported by US DOE contract DE-AC02-76SF00515.

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 over 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 at 4 GeV x 7 GeV are stored in low-emittance damping rings similar to those designed for a Linear Collider (LC). 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 (±30 mrad) is used at the collision point to allow beam separation and reduce the hourglass effect. Beam currents of about 3 A x 2 A in 1700 bunches can produce a luminosity of 1036/cm2/s. Design parameters and beam dynamics effects are discussed.

 
 
TUPAN037 Beam-Beam Simulations for Particle Factories with Crabbed Waist simulation, sextupole, resonance, emittance 1469
 
  • M. Zobov
  • P. Raimondi
    INFN/LNF, Frascati (Roma)
  • D. N. Shatilov
    BINP SB RAS, Novosibirsk
  The recently proposed "crabbed waist" scheme for beam-beam collisions can substantially increase luminosity since it combines several potentially advantageous ideas. Large crossing angle together with small horizontal beam size allow having very small beta-functions at the interaction point (IP) and ordinary bunch length without incurring in the "hourglass" effect. The other main feature of such a collision scheme is the "crabbed waist" transformation, which is realized by two sextupoles placed in proper betatron phases around the IP. Such a transformation can strongly suppress the beam-beam betatron resonances induced in collisions with large Piwinski's angle, thus providing significant luminosity increase and opening much more room for choices of the working point. In this paper we present the results of beam-beam simulations performed in order to optimize the parameters of two currently proposed projects with the crabbed waist: the DAFNE upgrade and the Super B-factory project.  
 
TUPAN041 Recent Progress of KEKB resonance, sextupole, emittance, vacuum 1475
 
  • Y. Funakoshi
  In this report, we describe the KEKB status focused on recent progress since the summer shutdown in 2005.  
 
TUPAN042 Synchroton Radiation Interferometer Calibration Check by Use of a Size Control Bump in KEKB coupling, sextupole, betatron, simulation 1478
 
  • N. Iida
  • J. W. Flanagan, Y. Funakoshi, K. Oide
    KEK, Ibaraki
  KEKB B-Factory is one of the second generation lepton colliders. The energies of the two beams are 3.5 GeV for positron and 8 GeV for electron. Synchrotron Radiation Monitors(SRMs) are installed in the both rings and usually used for measuring beam sizes on real times. On the other hand, we use useful vertical bumps to control beam sizes of the beams. In this paper a method for calibrating the SRM by using the vertical bumps is described.  
 
TUPAN045 Beam Operation with Crab Cavities at KEKB emittance, resonance, simulation, optics 1487
 
  • H. Koiso
  • T. Abe, T. A. Agoh, K. Akai, M. Akemoto, A. Akiyama, A. Arinaga, K. Ebihara, K. Egawa, A. Enomoto, J. W. Flanagan, S. Fukuda, H. Fukuma, Y. Funakoshi, K. Furukawa, T. Furuya, K. Hara, T. Higo, S. Hiramatsu, H. Hisamatsu, H. Honma, T. Honma, K. Hosoyama, T. Ieiri, N. Iida, H. Ikeda, M. Ikeda, S. Inagaki, S. Isagawa, H. Ishii, A. Kabe, E. Kadokura, T. Kageyama, K. Kakihara, E. Kako, S. Kamada, T. Kamitani, K.-I. Kanazawa, H. Katagiri, S. Kato, T. Kawamoto, S. Kazakov, M. Kikuchi, E. Kikutani, K. Kitagawa, Y. Kojima, I. Komada, T. Kubo, K. Kudo, N. K. Kudo, K. Marutsuka, M. Masuzawa, S. Matsumoto, T. Matsumoto, S. Michizono, K. Mikawa, T. Mimashi, S. Mitsunobu, K. Mori, A. Morita, Y. Morita, H. Nakai, H. Nakajima, T. T. Nakamura, H. Nakanishi, K. Nakao, S. Ninomiya, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, Y. Ohsawa, N. Ohuchi, K. Oide, M. Ono, T. Ozaki, K. Saito, H. Sakai, Y. Sakamoto, M. Sato, M. Satoh, K. Shibata, T. Shidara, M. Shirai, A. Shirakawa, T. Sueno, M. Suetake, Y. Suetsugu, R. Sugahara, T. Sugimura, T. Suwada, O. Tajima, S. Takano, S. Takasaki, T. Takenaka, Y. Takeuchi, M. Tawada, M. Tejima, M. Tobiyama, N. Tokuda, S. Uehara, S. Uno, Y. Yamamoto, Y. Yano, K. Yokoyama, Ma. Yoshida, M. Yoshida, S. I. Yoshimoto, K. Yoshino
    KEK, Ibaraki
  • E. Perevedentsev
    BINP SB RAS, Novosibirsk
  Beam operation with crab cavities is planned in early 2007 at KEKB. The crab crossing scheme is expected to increase the vertical beam-beam tune-shift parameter significantly. One crab cavity will be installed in each ring where conditions for beam optics are matched to compensate the beam crossing angle of 22 mrad. Operation results on collision tuning with the crab cavities will be presented.

For the KEKB Accelerator Group.

 
 
TUPAN048 Beam-beam Effects With an External Noise in LHC emittance, simulation, feedback, betatron 1496
 
  • K. Ohmi
  • R. Calaga
    BNL, Upton, Long Island, New York
  • W. Hofle, R. Tomas, F. Zimmermann
    CERN, Geneva
  Proton beam do not have any damping mechanism for an incoherent betatron motion. A noise, which kicks beam particles in the transverse plane, gives a coherent betatron amplitude. Nonlinear force due to the beam-beam interactions causes a decoherence for the betatron motion with keeping an amplitude of each beam particle, with the result that an emittance growth arises. We focus fast transverse turn by turn noises caused by a bunch by bunch feedback system and a cavity phase zitter in crab collision.  
 
TUPAN102 Numerical Study of the Very Forward Background from the Proton-Proton Collisions in the Experimental Insertions of the LHC simulation, background, hadron, insertion 1619
 
  • V. Talanov
  • H. Burkhardt, D. Macina, E. Tsesmelis
    CERN, Geneva
  The results from the numerical DPMJET-FLUKA simulation of the background in the experimental IR's of the LHC are presented. DPMJET3 is used for the generation and analysis of the products from the p-p collision leaving the interaction point in the very forward region. A multi-particle transport code FLUKA is used for the simulation of the resulting secondary cascades in the structure of the LHC long straight sections. The background formation is estimated and analyzed in the LSS's at the locations of the TAN absorber, Roman Pot stations and Beam Loss Monitors, for the purposes of the machine protection and planning of the operation of the detectors.  
 
TUPAS031 Analysis of Optics Designs for the LHC IR Upgrade optics, sextupole, resonance, quadrupole 1718
 
  • T. Sen
  • J. A. Johnstone
    Fermilab, Batavia, Illinois
  We consider the different options proposed for the LHC IR upgrade. The two main categories: quadrupoles first (as in the baseline design) and dipoles first have complementary strengths. We analyse the potential of the proposed designs by calculating important performance parameters including luminosity reach, beam-beam resonances and chromaticity contributions. The goal is to enable a decision on the design path based on objective criteria.  
 
TUPAS070 Optimization of Chromatic Optics Near the Half Integer in PEP-II lattice, sextupole, optics, quadrupole 1814
 
  • G. Yocky
  • Y. Cai, F.-J. Decker, Y. Nosochkov, U. Wienands
    SLAC, Menlo Park, California
  • P. Raimondi
    INFN/LNF, Frascati (Roma)
  Measurements of the W-function in PEP-II during Run 5 revealed that the chromatic beta functions in both the HER and LER were not optimized. Through a process of measurement, offline analysis and modelling, and high-current run implementation the PEP-II collider luminosity performance was increased by at least 10% by reconfiguring the strengths of sextupoles near the IP to take advantage of a minimized W and increased IP bandwidth.  
 
TUPAS089 Small Angle Crab Compensation for LHC IR Upgrade emittance, coupling, simulation, damping 1853
 
  • R. Calaga
  • K. Akai, K. Ohmi, K. Oide
    KEK, Ibaraki
  • U. Dorda, R. Tomas, F. Zimmermann
    CERN, Geneva
  Funding: This work is partially supported by the U. S. DOE

A small angle (< 1mrad) crab scheme is an attractive option for the LHC luminosity upgrade to recover the geometric luminosity loss from the finite crossing angle, which steeply increases to unacceptable levels as the IP beta function is reduced below its nominal value. The crab compensation in the LHC can be accomplished using only two sets of deflecting rf cavities, placed in collision-free straight sections of LHC to nullify the crossing angles at IP1 & IP5. We present IR optics configurations with low-angle crab crossing, study the beam-beam performance and proton-beam emittance growth in the presence of crab compensation, lattice errors, crab RF noise sources. We also explore a 400MHz superconducting cavity design and discuss the pertinent RF challenges.

 
 
TUPAS094 Transverse Beam Transfer Functions of Colliding Beams in RHIC simulation, proton, coupling, damping 1856
 
  • W. Fischer
  • M. Blaskiewicz, R. Calaga, P. Cameron, Y. Luo
    BNL, Upton, Long Island, New York
  • T. Pieloni
    CERN, Geneva
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH1-886.

We use transverse beam transfer functions to measure tune distributions of colliding beams in RHIC. The tune has a distribution due to the beam-beam interaction, nonlinear magnetic fields – particularly in the interaction region magnets, and non-zero chromaticity in conjunction with momentum spread. The measured tune distributions are compared with calculations.

 
 
TUPAS099 A Near-Integer Working Point for Polarized Protons in the Relativistic Heavy Ion Collider resonance, dynamic-aperture, proton, polarization 1871
 
  • C. Montag
  • M. Bai, J. Beebe-Wang, M. Blaskiewicz, R. Calaga, W. Fischer, A. K. Jain, Y. Luo, N. Malitsky, T. Roser, S. Tepikian
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the US Department of Energy.

To achieve the RHIC polarized proton enhanced luminosity goal of 150*1030 cm-2 sec-1 on average in stores at 250 GeV, the luminosity needs to be increased by a factor of 3 compared to what was achieved in 2006. Since the number of bunches is already at its maximum of 111, limited by the injection kickers and the experiments' time resolution, the luminosity can only be increased by either increasing the bunch intensity and/or reducing the beam emittance. This leads to a larger beam-beam tuneshift parameter. Operation during 2006 has shown that the beam-beam interaction is already dominating the luminosity lifetime. To overcome this limitation, a near-integer working point is under study. We will present recent results of these studies.

 
 
TUPAS103 RHIC Challenges for Low Energy Operations injection, proton, power-supply, electron 1877
 
  • T. Satogata
  • L. Ahrens, M. Bai, J. M. Brennan, D. Bruno, J. J. Butler, K. A. Drees, A. V. Fedotov, W. Fischer, M. Harvey, T. Hayes, W. Jappe, R. C. Lee, W. W. MacKay, G. J. Marr, R. J. Michnoff, B. Oerter, E. Pozdeyev, T. Roser, F. Severino, K. Smith, S. Tepikian, N. Tsoupas
    BNL, Upton, Long Island, New York
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH1-886

There is significant interest in RHIC heavy ion collisions at c.m. energies of 5-50 GeV/u, motivated by a search for the QCD phase transition critical point. The low end of this energy range is well below the nominal RHIC injection c.m. energy of 19.6 GeV/u. There are several challenges that face RHIC operations in this regime, including longitudinal acceptance, magnet field quality, lattice control, and luminosity monitoring. We report on the status of work to address these challenges and include results from beam tests of low-energy RHIC operations with protons and gold.

 
 
TUPAS107 Proton Beam Emittance Growth at RHIC emittance, electron, proton, injection 1886
 
  • S. Y. Zhang
  • V. Ptitsyn
    BNL, Upton, Long Island, New York
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH1-886

The beam emittance growth in RHIC polarized proton runs has a dependence on the dynamic pressure rise, which is caused by the electron cloud and peaked at the end of the beam injection and the early energy acceleration. This emittance growth is usually presented without beam instability, and it is slower than the ones above the instability threshold. The effect on the machine luminosity, nevertheless, is significant, and it is currently a limiting factor in machine performance. The electron cloud is substantially reduced at the store, the emittance growth there has no dependence on the bunch spacing and instead it has a clear dependence on the beam-beam parameter. The results of the machine operation and beam studies will be reported.

 
 
WEZAKI01 Run II Luminosity Progress antiproton, target, electron, proton 1922
 
  • K. Gollwitzer
  Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

The Fermilab Tevatron Collider Run II program continues at the energy and luminosity frontier of high energy particle physics. The presentation will cover major improvements in the performance of the collider complex which lead to the record-breaking luminosity.

 
slides icon Slides  
 
WEOCKI01 Operational Experience with HERA proton, electron, feedback, polarization 1932
 
  • J. Keil
  The electron-proton collider HERA (Hadron Electron Ring Accelerator) at DESY which collides 920 GeV protons with polarized electrons or positrons with an energy of 27.5 GeV will conclude operations in July 2007 after 16 successful years. After an upgrade of the interaction regions in the year 2001 the luminosity of HERA has been increased by a factor of 2.5 resulting in a peak value of 5.1*1031 cm-2 s-1. For a special experiment, HERA will run in the last three month of operation with a reduced proton energy of 460 GeV. An overview of the accelerator physics and operational challenges, the performance over the last years, the continuous efforts to upgrade and improve the accelerator and an assessment of reliability and availability issues of HERA will be presented.  
slides icon Slides  
 
WEOCKI02 Design of High Luminosity Ring-Ring Electron-Light Ion Collider at CEBAF electron, ion, collider, emittance 1935
 
  • Y. Zhang
  • S. A. Bogacz, P. B. Brindza, A. Bruell, L. S. Cardman, J. R. Delayen, Y. S. Derbenev, R. Ent, P. Evtushenko, J. M. Grames, A. Hutton, G. A. Krafft, R. Li, L. Merminga, J. Musson, M. Poelker, A. W. Thomas, B. Wojtsekhowski, B. C. Yunn
    Jefferson Lab, Newport News, Virginia
  • V. P. Derenchuk
    IUCF, Bloomington, Indiana
  • V. G. Dudnikov
    BTG, New York
  • W. Fischer, C. Montag
    BNL, Upton, Long Island, New York
  • P. N. Ostroumov
    ANL, Argonne, Illinois
  Funding: Authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177.

Experiments on the study of fundamental quark-gluon structure of nucleons require an electron-light ion collider of a center of mass energy from 20 to 65 GeV at luminosity level of 1035 cm-2s-1 with both beams polarized. A CEBAF accelerator based ring-ring collider of 7 GeV electrons/positrons and 150 GeV light ions is envisioned as a possible next step after the 12 GeV CEBAF Upgrade. The developed ring-ring scheme takes advantage of the existing polarized continuous electron beam and SRF linac, the green-field design of the collider rings and the ion accelerator complex with electron cooling. We report results of our design studies of the ring-ring version of an electron-light ion collider of the required luminosity.

 
slides icon Slides  
 
WEOCKI04 Longitudinal Momentum Mining of Antiprotons at the Fermilab Recycler: Past, Present, and Future antiproton, emittance, collider, injection 1941
 
  • C. M. Bhat
  • B. Chase, C. Gattuso, P. W. Joireman
    Fermilab, Batavia, Illinois
  Funding: Operated by Universities Research Association, Inc. for the U. S. Department of Energy under contract DE-AC02-76CH03000.

The Recycler is the primary antiproton repository for the Tevatron collider at Fermilab. Stored antiproton beam intensity has been steadily increased to about 450·1010 over the last three years. We have used the technique of longitudinal momentum mining* in the Recycler to extract constant intensity and constant longitudinal emittance antiproton bunches for collider operation since early 2005. Since then, the Recycler has played a critical role in the luminosity performance of the Tevatron; the peak proton-antiproton luminosity has been raised by a factor of about three and a world record luminosity of 2.31·1032cm-2s-1 has been achieved. Recently, many improvements have been implemented in the antiproton mining and stacking schemes used in the Recycler to handle higher intensity beam. In this paper we discuss morphing during antiproton stacking, reducing longitudinal emittance dilution, and use of soft mining buckets to maintain low peak density and control the beam instability during mining. In addition we present past and current performance of mining and beam stacking RF manipulations.

* C. M. Bhat, Phys. Letts. A Vol. 330 (2004), p 481

 
slides icon Slides  
 
WEYAB02 Availability and Reliability Issues for ILC simulation, power-supply, klystron, linac 1966
 
  • T. M. Himel
  • J. Nelson, N. Phinney
    SLAC, Menlo Park, California
  • M. C. Ross
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U. S. Department of Energy under contract number DE-AC03-76SF00515.

The International Linear Collider will be the largest most complicated accelerator ever built. For this reason extensive work is being done early in the design phase to ensure that it will be reliable enough. This includes gathering failure mode data from existing accelerators and simulating the failures and repair times of the ILC. This simulation has been written in a general fashion using MATLAB and could be used for other accelerators. Results from the simulation tool have been used in making some of the major ILC design decisions and an unavailability budget has been developed.

 
slides icon Slides  
 
WEOBAB01 Electromagnetic Background Tests for the ILC Interaction Point Feedback System feedback, background, electron, extraction 1970
 
  • P. Burrows
  • R. Arnold, S. Molloy, S. Smith, G. R. White, M. Woods
    SLAC, Menlo Park, California
  • G. B. Christian, C. I. Clarke, B. Constance, A. F. Hartin, H. D. Khah, C. Perry, C. Swinson, G. R. White
    JAI, Oxford
  • A. Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  We present results obtained with the T-488 experiment at SLAC Endstation A (ESA). A material model of the ILC extraction-line design was assembled and installed in ESA. The module includes materials representing the mask, beamline calorimeter, and first extraction quadrupole, encompassing a stripline interaction-point feedback system beam position monitor (BPM). The SLAC high-energy electron beam was used to irradiate the module in order to mimic the electromagnetic (EM) backgrounds expected in the ILC interaction region. The impact upon the performance of the feedback BPM was measured, and compared with detailed simulations of its expected response.  
slides icon Slides  
 
WEOCAB02 Automatic Luminosity Optimisation of the ILC Head-On BDS quadrupole, linear-collider, collider, extraction 1988
 
  • J. Payet
  • S. Auclair, A. Chance, O. Napoly, D. Uriot
    CEA, Gif-sur-Yvette
  Funding: EUROTeV Project Contract no.011899 RIDS

With the local chromaticity correction scheme, the luminosity optimisation of the beam delivery systems of the e+ e- International Linear Collider (ILC) project is challenging. A manual optimization is a long and complex process and its automation becomes a necessity. Recent works have shown that it was possible to employ a simplex minimization method, applied to the beam size calculation at the Interaction Point (IP), to reach this objective automatically *. To achieve this goal in the ILC case, we have developed a minimization code which uses analytical computations of the IP beam sizes based on external code results, TRANSPORT** or MADX (with PTC extension)***. Two minimization algorithms can be employed. The maximum luminosity reached and the convergence time of the two codes and algorithms are compared. We also used the code TRACEWIN which tracks a particle cloud and minimise the rms beam spot sizes at IP to optimise the luminosity, and we compare with the previous results.

* Non-linear optimization of beam lines, R. Tomas, CLIC Note 659** Third-Order TRANSPORT with MAD Input, D. C. Carey, K. L. Brown and F. Rothacker, FERMILAB-Pub-98/310*** MADX User's Guide CERN

 
slides icon Slides  
 
THPMN005 Technical Challenges for Head-On Collisions and Extraction at the ILC extraction, quadrupole, optics, collimation 2716
 
  • O. Napoly
  • M. Alabau, P. Bambade, J. Brossard, O. Dadoun, C. Rimbault
    LAL, Orsay
  • D. A.-K. Angal-Kalinin, F. Jackson, S. I. Tzenov
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R. Appleby
    UMAN, Manchester
  • B. Balhan, J. Borburgh, B. Goddard
    CERN, Geneva
  • O. Delferriere, M. Durante, J. Payet, C. Rippon, D. Uriot
    CEA, Gif-sur-Yvette
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  • L. Keller
    SLAC, Menlo Park, California
  • S. Kuroda
    KEK, Ibaraki
  • G. L. Sabbi
    LBNL, Berkeley, California
  Funding: EUROTeV Project Contract no.011899 RIDS

An interaction region with head-on collisions is considered as an alternative to the baseline ILC configuration. Progress in the final focus optics design includes engineered large bore superconducting final doublet magnets and their 3D magnetic integration in the detector solenoids. Progress on the beam separation optics is based on technical designs of electrostatic separator and special extraction quadripoles. The spent beam extraction is realized by a staged collimation scheme relying on realistic collimators. The impact on the detector background is estimated. The possibility of technical tests of the most challenging components is investigated.

 
 
THPMN008 Evaluation of Luminosity Reduction in the ILC Head-on Scheme from Parasitic Collisions simulation, beam-beam-effects, extraction, injection 2722
 
  • J. Brossard
  • M. Alabau
    IFIC, Valencia
  • D. A.-K. Angal-Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. Bambade, T. Derrien
    LAL, Orsay
  • O. Napoly, J. Payet
    CEA, Gif-sur-Yvette
  An interaction region with head-on collisions is being developed for the ILC as an alternative to the base line 14 mrad crossing angle design, motivated by simpler beam manipulations upstream of the interaction point and a more favourable configuration for the detector and physics analysis. The design of the post-collision beam line in this scheme involves however a number of technological challenges, one of which is the strength requirement for the electrostatic separators placed immediately after the final doublet to extract the spent beam. In this paper, we examine in detail the main mechanism behind this requirement, the multi-beam kink instability, which results from the long-range beam-beam forces at the parasitic crossings after the bunches have been extracted. Our analysis uses realistic bunch distributions, the Guinea-Pig program to treat beam-beam effects at the interaction point and the DIMAD program to track the disrupted beam distributions in the post-collision beam line. A version of the beam-beam deflection based interaction point feedback system with an improved filtering algorithm is also studied to mitigate the luminosity deterioration from the instability.  
 
THPMN010 GUINEA-PIG++ : An Upgraded Version of the Linear Collider Beam-Beam Interaction Simulation Code GUINEA-PIG simulation, background, linear-collider, collider 2728
 
  • C. Rimbault
  • M. Alabau
    IFIC, Valencia
  • P. Bambade, O. Dadoun, G. Le Meur, F. Touze
    LAL, Orsay
  • D. Schulte
    CERN, Geneva
  GUINEA-PIG++ is a newly developed object-oriented version of the Linear Collider beam-beam simulation program GUINEA-PIG. The main goals of this project are to provide a reliable, modular, documented and versatile framework enabling convenient implementation of new features and functionalities. Examples of improvements described in this paper are an easy interface to study the impact of electromagnetic effects on Bhabha event selections, a treatment of spin depolarization effects, automatic consistency checks and adjustments of internal computational parameters, upgraded input/output and user interface, an optimised setup for massive production on distributed computing GRIDs. A possible setup to perform fast parallelised computations is also discussed.  
 
THPMN056 Comparison of ILC Fast Beam-Beam Feedback Performance in the e-e- and e+e- Modes of Operation feedback, ground-motion, simulation, lattice 2832
 
  • M. Alabau
  • P. Bambade
    LAL, Orsay
  • A. Faus-Golfe
    IFIC, Valencia
  • A. Latina, D. Schulte
    CERN, Geneva
  Several feedback loops are required in the Beam Delivery System (BDS) of the International Linear Collider (ILC) to preserve the luminosity in the presence of dynamic imperfections. Realistic simulations have been carried out to study the performance of the beam-beam deflection based fast feedback system, for both e+e- and e-e- modes of operation. The beam-beam effects in the e-e- collisions make both the luminosity and the deflections more sensitive to offsets at the IP than in the case of the e+e- collisions. This reduces the performance of the feedback system in comparison to the standard e+e- collisions, and may require a different beam parameter optimization.  
 
THPMN059 Feedback Studies feedback, emittance, ground-motion, linac 2841
 
  • A. Latina
  • G. Rumolo, D. Schulte, R. Tomas
    CERN, Geneva
  Funding: Supported by the European Community under the 6th Framework Programme "Structuring the European Research Area".

Dynamic imperfections in future linear colliders can lead to a significant luminosity loss. We discuss different orbit feedback strategies in the main linac that can mitigate the emittance dilution and compare their efficiency. We also address the impact of ground motion in the beam delivery system and the potential cures.

 
 
THPMN064 Luminosity Upgrade of CLIC-LHC ep/gp Collider collider, electron, photon, proton 2853
 
  • H. Aksakal
  • A. K. Ciftci, Z. Nergiz
    Ankara University, Faculty of Sciences, Tandogan/Ankara
  • D. Schulte, F. Zimmermann
    CERN, Geneva
  An energy-frontier or QCD-exploring ep and gp collider can be realized by colliding high-energy photons generated by Compton back-scattered off a CLIC electron beam, at either 75 GeV or 1.5 TeV, with protons or ions stored in the LHC. In this study we discuss a performance optimization of this type of collider by tailoring the parameters of both CLIC and LHC. An estimate of the ultimately achievable luminosity is given.  
 
THPMN073 Collimation Optimisation in the Beam Delivery System of the International Linear Collider collimation, lattice, betatron, quadrupole 2871
 
  • F. Jackson
  • R. J. Barlow, A. M. Toader
    UMAN, Manchester
  • A. Latina, D. Schulte
    CERN, Geneva
  The collimation systems of the International Linear Collider (ILC) Beam Delivery System (BDS) must perform efficient removal of halo particles which lie outside the acceptable ranges of energy and spatial spread. An optimisation strategy based on earlier work is applied to the latest version of the BDS lattice. The resulting improvement in collimation performance is studied by halo tracking simulations, and the luminosity performance of the optimised lattice is also examined.  
 
THPMN077 Improved 2mrad crossing angle layout for the International Linear Collider extraction, quadrupole, optics, beam-losses 2883
 
  • R. Appleby
  • D. A.-K. Angal-Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. Bambade, S. Cavalier, O. Dadoun
    LAL, Orsay
  • D. Toprek
    UMAN, Manchester
  The 2mrad interaction region and extraction line provide several machine and physics advantages, but also involves a number of technological challenges. In this paper a minimal extraction line without beam energy and polarization diagnostics is presented, which considerably simplifies the design and reduces costs. The optimization of the interaction region sextupoles, using current and proposed technologies, and an estimation of photon backscattering from spent beam particle losses are described. Overall performance is evaluated and compared with previous designs. The upgrade to 1 TeV and the possibility of including diagnostics are considered.  
 
THPMN080 Incoherent pair background processes with full polarizations at the ILC polarization, photon, background, collider 2892
 
  • A. F. Hartin
  Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899.

Incoherent background pair production processes are studied with respect to full polarizations of all states. Real initial photon polarizations are obtained via a QED calculation of the beamstrahlung process. Virtual photon polarizations are related to the electric field of the colliding bunches at the point of pair production. An explicit expression for the virtual photon polarization vector is developed and found to have no circular polarization component. Pair polarization states are highly dependent on initial state circular polarization and are consequently produced almost unpolarized. The Breit-Wheeler cross-section with full polarizations is calculated and coded into the CAIN pair generator program. Numerical evaluations of the ILC operating in the seven proposed collider parameter sets shows that there are 10-20% less low energy pairs than previously thought. Collider luminosity as calculated by CAIN remains the same.

 
 
THPMN095 Muon Bunch Coalescing collider, emittance, lattice, factory 2930
 
  • R. P. Johnson
  • C. M. Ankenbrandt, C. M. Bhat, M. Popovic
    Fermilab, Batavia, Illinois
  • S. A. Bogacz, Y. S. Derbenev
    Jefferson Lab, Newport News, Virginia
  Funding: Supported in part by DOE STTR grants DE-FG02-04ER86191 and -05ER86253.

The idea of coalescing multiple muon bunches at high energy to enhance the luminosity of a muon collider provides many advantages. It circumvents space-charge, beam loading, and wakefield problems of intense low-energy bunches while restoring the synergy between muon colliders and neutrino factories based on muon storage rings. A sampling of initial conceptual design work for a coalescing ring is presented here.

 
 
THPAN023 MERLIN-Based Start-to-End Simulations of Luminosity Stability for the ILC simulation, ground-motion, linac, emittance 3277
 
  • D. Kruecker
  • F. Poirier, N. J. Walker
    DESY, Hamburg
  Funding: Supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899.

The International Linear Collider (ILC) requires the preservation of an ultra-small vertical emittance from the Damping Ring to the Interaction Point (IP) where the nanometre-sized beams are made to collide. It is well-known that ground motion and component vibration will need to be compensated by fast intra-train feedback systems and slower semi-continuous trajectory corrections. This complex system can in general only be modelled using simulation. In this paper, we report the progress and status of a full-featured so-called start-to-end simulation based on the MERLIN package of the ILC Low Emittance Transport (LET): Bunch compression, acceleration in the superconducting Main Linac, Beam Delivery System and finally collision at the IP. Realistic modelling of the beam-beam is included by using the code GUINEAPIG. Results based on several ground motion and vibration models and configurations of trajectory control are presented.

 
 
THPAN037 Beam-Beam Effects Observed at KEKB simulation, feedback, emittance, betatron 3309
 
  • Y. Funakoshi
  • K. Ohmi, K. Oide, M. Tawada
    KEK, Ibaraki
  KEKB is an e+ e- collider with a world-highest luminosity of 1.7 x 1034 /cm2/s. It has a half-crossing angle of 11 mrad. We are installing crab cavities for the purpose of eliminating effects of crossing angle in the begining of 2007. Another feature of KEKB is that its operating points are very close to the half interger in the horizontal direction. This report summarizes beam-beam effects observed at KEKB.  
 
THPAN072 A Concept for the LHC Luminosity Upgrade Based on Strong Beta* Reduction Combined with a Minimized Geometrical Luminosity Loss Factor separation-scheme, quadrupole, collimation, dipole 3387
 
  • E. Todesco
  • R. W. Assmann, J.-P. Koutchouk, E. Metral, G. Sterbini, F. Zimmermann, R. de Maria
    CERN, Geneva
  A significant increase of the LHC beam current touches physics limits as collective effects, electron-cloud, heat load, collimation and machine protection. We propose an upgrade scheme mainly based on a stronger focusing, with a beta* of 10 cm, requiring a triplet quadrupole aperture of around 130 mm. The performance is further improved if the triplet is based on the Nb3Sn technology. In the present baseline, this beta* reduction provides a negligible luminosity increase: this approach requires a drastic action to minimize the crossing angle, while the beam separation at the long-range encounters has to be increased. This is provided by an early separation scheme made of small dipoles inside the detectors. Optionally, a small angle crab cavity scheme may totally suppress the residual crossing angle. The quadrupole aperture is calculated to allow a larger gap for the collimator, suppressing their impedance limitation. This concept offers high performance while significantly reducing the risks associated to a beam current increase; it opens as well new issues that deserve further studies, such as the dipole integration in the detector, and the correction of the triplet aberrations.  
 
THPAN079 Emittance Growth Due to High Order Angular Multipole Mode Wakefields in the ILC-BDS Collimators higher-order-mode, emittance, simulation, collider 3402
 
  • A. Bungau
  • R. J. Barlow
    UMAN, Manchester
  The passage of an off-axis bunch through the collimator gap induces higher order mode wakefields which can lead to emittance growth and consequently can affect the luminosity at the IP - a major concern for the ILC. The emittance growth due to high order angular multipole mode wakefields is calculated and beam profiles at the IP are presented in this paper.  
 
THPAS057 Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps sextupole, background, coupling, lattice 3618
 
  • F.-J. Decker
  • Y. Nosochkov, M. K. Sullivan, G. Yocky
    SLAC, Menlo Park, California
  Funding: *Work supported by Department of Energy contract DE-AC03-76SF00515.

Orbit bumps in sextupoles are routinely used for tuning the luminosity in the PEP-II B-Factory. Anti-symmetric bumps in a sextupole pair generate dispersion, while symmetric bumps induce a tune shift and beta beat. By coming two of these symmetric bumps with opposite signs where the second pair is 90 degree away, the tune shift cancels and the beta beat doubles. In the low energy ring (LER) we have four sextupole pairs per arc, where pair 1 and 3 are at the same betatron phase and pair 2 and 4are 90 degree away. By making two symmetric bumps with opposite sign in pair 1 and 3 the tune shift and the beta beat outside this region cancel, BUT the LER lifetime improved by a factor of three, losses by a factor of five, and the beam-beam background in the drift chamber of the BaBar detector by 20%. Simulations showed that the phase change at the second sextupole pair introduced by the beta beat can completely cancel the third order chromaticity.

 
 
THPAS058 Lowering the Vertical Emittance in the LER Ring of PEP-II emittance, quadrupole, coupling, permanent-magnet 3621
 
  • F.-J. Decker
  • Y. Cai, Y. Nosochkov, Y. T. Yan, G. Yocky
    SLAC, Menlo Park, California
  Funding: *Work supported by Department of Energy contract DE-AC03-76SF00515.

The low energy ring (LER) in PEP-II has a design emittance of 0.5 nm-rad in the vertical, compared to nearly 0.1 nm-rad for the HER ring. This was thought to come from the "vertical step" of about 1 m in the interaction straight, where the LER beam after horizontal separation gets bend vertical so it sits on top of the HER in the rest of the ring. Since the program MAD does not easily reveal the location of the major emittance contribution, a program was written to calculate the coupled "curly H" parameter of mode 2 (mainly vertical) along z. Weighting it with the magnet bending revealed that the weak long bends inside the "vertical step" did less than 20% of the emittance growth. More than 80% comes from the ends of the adjacent arcs with strong bends. This is caused by the coupling cancellation of the solenoid starting already there with the skew quadrupoles SK5 and 6. By introducing additional skews in the straight instead of SK5 and 6 the emittance could be reduced by a factor of ten in simulations, but with very strong skews. Reasonable strong magnets might generate a workable compromise, since a factor of two in emittance promises 50% more luminosity in beam-beam simulations.

 
 
FRXKI03 Magnets for Upgrade of the Accelerator Complex at CERN quadrupole, interaction-region, superconducting-magnet 3738
 
  • L. Rossi
  While the LHC is approaching commissioning phase, a global plan with different options for the consolidation and upgrade of the accelerator complex is under discussion at CERN. In one option the change of the interaction region (IR) magnets, in order to increase the luminosity of the LHC, is considered. This measure may be accompanied or not by an increase of the beam current. In any case the needs of new more performing Nb-Ti based magnets and/or Nb3Sn magnets is established. The choice of Nb3Sn based magnets with13-15 T peak field on the coil seems mandatory for the low-beta triplet quadrupoles in case a factor two or more in luminosity is envisaged. In another option the improvement of the injector chain is considered. For the moment the first priority is the design of a new PS of energy about 50 GeV, with duty cycle less than 1 Hz. In this paper a comparison among the option based on normal conducting magnets (today baseline) and superconducting magnets of various types will be presented. In the frame of the longer-term scenario, magnets envisaged for an upgrade of the present SPS (from 450 to 1 TeV) and for neutrino production facilities will be discussed as well.  
slides icon Slides  
 
FRZKI01 Physics from Tevatron to LHC and ILC coupling, collider, lepton, scattering 3830
 
  • M. Mangano
  The physics reach of LHC and the need of ILC beams in the investigation of the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics.  
slides icon Slides  
 
FRPMN012 Bias on Absolute Luminosity Measurements at the ILC from Beam-Beam Space Charge Effects scattering, space-charge, linear-collider, simulation 3907
 
  • C. Rimbault
  • P. Bambade
    LAL, Orsay
  • K. Moenig
    DESY Zeuthen, Zeuthen
  • D. Schulte
    CERN, Geneva
  A way to determine luminosity at the International Linear Collider (ILC) is to measure the Bhabha event rate in a finely segmented calorimeter (LumiCal) at very low polar angles in the very forward region of the detector. An absolute precision between 10-4 and 10-3 is needed for a number of key physics measurements. Besides theoretical uncertainties on the Bhabha cross section and experimental errors when identifying Bhabha events in the LumiCal, the very strong beam-beam space charge effects which characterise the ILC e+e- collisions lead to a major bias in the counting rate, which drastically limits the luminosity measurement if uncorrected. In this paper, Bhabha event samples produced with the BHLUMI generator are used in the context of the GUINEA-PIG beam-beam simulation to study how beamstrahlung radiation and electromagnetic deflections affect the proposed experimental selections. A corrective method based on determining the luminosity spectrum within the LumiCal is suggested to minimise the resulting errors. The expected residual uncertainty after correction is estimated based on simulations with realistic beam conditions.  
 
FRPMN035 Crabbing Angle Measurement by Streak Camera at KEKB optics, synchrotron, synchrotron-radiation, betatron 4018
 
  • H. Ikeda
  • J. W. Flanagan, H. Fukuma, S. Hiramatsu, T. Mitsuhashi
    KEK, Ibaraki
  Crab cavities will be installed in the KEKB rings in order to increase luminosity. We measure the crabbing angle using a streak camera and show the results in this paper.  
 
FRPMN041 Study on the Longitudinal Impedance of BPM for KEKB and Super KEKB impedance, resonance, simulation, damping 4048
 
  • K. Shibata
  • H. Fukuma, S. Hiramatsu, Y. Suetsugu, M. Tejima, M. Tobiyama
    KEK, Ibaraki
  The longitudinal impedance of the KEK B-factory (KEKB) button-type beam position monitors (BPMs) was recalculated by MAFIA in preparation for a future plan to increase the beam current. The diameter and the gap of the button electrode were 12 mm and 1 mm, respectively. For High Energy Ring (HER), an asymmetric structure was applied to extract the TE110 mode into the coaxial cable. The Q-value and shunt impedance were estimated at 91 and 17 Ω (at 7.6 GHz) respectively, and the beam current limit for longitudinal multi-bunch instability was 2.6 A. On the other hand, the electrode of Low Energy Ring (LER) BPM had a symmetric structure and the Q-value and shunt impedance were estimated at 133 and 8 Ω (at 7.6 GHz). In this case, the current limit was 1.7 A. Based on the experiences at the KEKB, the new BPM was designed for the Super KEKB, a future high-intensity B-factory at KEK. In order to reduce the impedance the electrode diameter was cut down to 6 mm from 12 mm. The Q-value and shunt impedance were estimated at 23 and 2 Ω (at 13 GHz). The current limit was expected to be about 7 A in full bucket operation (5120 bunches), and more than 10 kA in 4-bucket spacing operation.  
 
FRPMN067 Collision Rate Monitors for LHC radiation, simulation, proton, optics 4171
 
  • E. Bravin
  • A. Brambilla, M. Jolliot, S. Renet
    CEA, Grenoble
  • S. Burger, C. Dutriat, T. Lefevre, V. Talanov
    CERN, Geneva
  • J. M. Byrd, K. Chow, H. S. Matis, M. T. Monroy, A. Ratti, W. C. Turner
    LBNL, Berkeley, California
  Collision rate monitors are essential in bringing particle beams into collision and optimizing the performances of a collider. In the case of LHC the relative luminosity will be monitored by measuring the flux of small angle neutral particles produced in the collisions. Due to the very different luminosity levels at the four interaction regions (IR) of LHC two different types of monitors have been developed. At the high luminosity IR (ATLAS and CMS) fast ionization chambers will be installed while at the other two (ALICE and LHC-b) solid state polycrystalline Cadmium Telluride (CdTe) detectors will be used. The ionization chambers are being developed by Lawrence Berkeley National Lab (Berkeley CA, USA) while the CdTe monitors are being developed by CERN and CEA-LETI (Grenoble, FR) This paper describes the system with particular emphasis on the monitors based on CdTe detectors, detailed description of the ionisation chambers being available in separate papers.  
 
FRPMS032 High-Order Modeling of an ERL for Electron Cooling in the RHIC Luminosity Upgrade using MaryLie/IMPACT space-charge, electron, linac, simulation 4000
 
  • V. H. Ranjbar
  • D. T. Abell, K. Paul
    Tech-X, Boulder, Colorado
  • I. Ben-Zvi, J. Kewisch
    BNL, Upton, Long Island, New York
  • J. Qiang, R. D. Ryne
    LBNL, Berkeley, California
  Funding: Work supported by the U. S. DOE Office of Science, Office of Nuclear Physics under grant DE-FG02-03ER83796.

Plans for the RHIC luminosity upgrade call for an electron cooling system that will place substantial demands on the energy, current, brightness, and beam quality of the electron beam. In particular, the requirements demand a new level of fidelity in beam dynamics simulations. New developments in MaryLie/IMPACT have improved the space-charge computations for beams with large aspect ratios and the beam dynamic computations for rf cavities. We present the results of beam dynamics simulations that include the effects of space charge and nonlinearities, and aim to assess the tolerance for errors and nonlinearities on current designs for a super-conducting ERL.

 
 
FRPMS066 Commissioning the Fast Luminosity Dither for PEP-II feedback, electron, positron, controls 4165
 
  • A. S. Fisher
  • S. Ecklund, R. C. Field, S. M. Gierman, P. Grossberg, K. E. Krauter, E. S. Miller, M. Petree, N. Spencer, M. K. Sullivan, K. K. Underwood, U. Wienands
    SLAC, Menlo Park, California
  • K. G. Sonnad
    LBNL, Berkeley, California
  Funding: Supported by US DOE under contract DE-AC03-76SF00515.

To maximize luminosity, a feedback system adjusts the relative transverse (x,y) position and vertical angle (y') of the electron and positron beams at the interaction point (IP) of PEP-II. The original system sequentially moved ("dithered") the electrons in four steps per coordinate. Communication with DC corrector magnets and field penetration through copper vacuum chambers led to a full-cycle time of 10 s. Machine tuning can move the beams at the IP and so had to be slowed to wait for the feedback. A new system installed in 2006 simultaneously applies a small sinusoidal dither to all three coordinates at 73, 87 and 103 Hz. Air-core coils around stainless-steel chambers give rapid field penetration. A lock-in amplifier at each frequency detects the magnitude and phase of the luminosity's response. Then corrections for all coordinates are determined using Newton's method, based on convergence from prior steps, and are applied by the same DC correctors used previously but with only one adjustment per cycle for an expected ten-fold increase in speed. We report on the commissioning of this system and on its performance in maintaining peak luminosity and aiding machine tuning.

 
 
FRPMS075 Modeling of the Sparks in Q2-bellows of the PEP-II SLAC B-factory simulation, vacuum, radiation, electromagnetic-fields 4213
 
  • A. Novokhatski
  • J. Seeman, M. K. Sullivan
    SLAC, Menlo Park, California
  Funding: Work supported by USDOE contract DE-AC02-76SF00515

The PEP-II B-factory at SLAC has recently experienced unexpected aborts due to anomalously high radiation levels at the BaBar detector. Before the problem was finally traced we performed the wake field analysis of the Q-2 bellows, which is situated at a distance of 2.2 m from the interaction point. Analysis showed that electric field in a small gap between a ceramic tile and metal flange can be high enough to produce sparks or even breakdowns. Later the traces of sparks were found in this bellows.

 
 
FRPMS076 A New Q2-Bellows Absorber for the PEP-II SLAC B-Factory radiation, simulation, impedance, dipole 4219
 
  • A. Novokhatski
  • S. DeBarger, S. Ecklund, N. Kurita, J. Seeman, M. K. Sullivan, S. P. Weathersby, U. Wienands
    SLAC, Menlo Park, California
  Funding: Work supported by US DOE contract DE-AC02-76SF00515

A new Q2-bellows absorber will damp only transverse wake fields and will not produce additional beam losses due to Cherenkov radiation. The design is based on the results of the HOM analysis. Geometry of the slots and absorbing tiles was optimized to get maximum absorbing effect.

 
 
FRPMS077 High Current Effects in the PEP-II SLAC B-factory synchrotron, impedance, optics, vacuum 4225
 
  • A. Novokhatski
  • S. A. Heifets, D. Teytelman
    SLAC, Menlo Park, California
  Funding: Work supported by US DOE contract DE-AC02-76SF00515.

Wake fields defining beam stability affect also the beam optics and beam properties in high current machines. We present observations and analysis of the optical effects in the PEP-II SLAC B-factory, which has the record in achievement of high electron and positron currents. We study the synchronous phase and the bunch length variation along the train of bunches, overall bunch lengthening and effects of the wakes on the tune and on the Twiss parameters. This analysis is being used in upgrades of PEP II and may be applied to future B-factories and damping rings for Linear Colliders.

 
 
FRPMS096 Emittance Growth due to Beam-Beam Effect in RHIC emittance, simulation, beam-beam-effects, proton 4306
 
  • J. Beebe-Wang
  Funding: Work performed under the United States Department of Energy Contract No. DE-AC02-98CH1-886.

The beam-beam interaction has a significant impact on the beam emittance growth and the luminosity lifetime in RHIC. A simulation study of the emittance growth was performed using the Lifetrac code. The operational conditions of RHIC 2006 100GeV polarized proton run were used in the study. In this paper, the result of this study is presented and compared to the experimental measurements.