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sextupole

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MOOBKI01 Central Mass Energy Determination in High Precision Experiments on VEPP-4M luminosity, electron, positron, energy-calibration 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.

 
slides icon Slides  
 
MOOBKI02 DAΦ NE Phi-Factory Upgrade for Siddharta Run luminosity, 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

 
slides icon Slides  
 
MOPAN025 The Elettra Booster Magnets dipole, booster, quadrupole, multipole 206
 
  • D. Zangrando
  • D. Castronovo, M. Svandrlik, R. Visintini
    ELETTRA, Basovizza, Trieste
  The third generation light source ELETTRA has been in operation since 1993. A new 2.5 GeV full energy booster injector, that will replace the existing linear injector limited to a maximum energy of 1.2 GeV is now under construction and the commissioning will start this August. The paper reports on the construction of dipole, quadrupole, sextupole and steerer magnets and on the magnetic measurement results with a comparison with the requested specifications.  
 
MOPAN034 Development of a Pulsed Sextupole Magnet System for Beam Injection at the Photon Factory Storage Ring injection, emittance, betatron, synchrotron 230
 
  • Y. Kobayashi
  • K. Harada, T. Honda, T. Miyajima, S. Nagahashi
    KEK, Ibaraki
  • N. Nakamura, H. Takaki
    ISSP/SRL, Chiba
  We proposed a single pulsed sextupole system for beam injection in electron storage rings. Now we are going to design a pulsed sextupole magnet and a ceramic chamber and install them at the Photon Factory storage ring next summer. The required specifications of the magnet and the vacuum chamber are estimated using a multi-particle tracking simulation. In this conference, we describe the design of the hardware for the system and the field measurement of the pulsed magnet.  
 
MOPAN047 Mechanical Design Considerations for Sesame Main Subsystems dipole, vacuum, quadrupole, storage-ring 263
 
  • M. M. Shehab
  • G. Vignola
    SESAME, Amman
  Recent advances in the design and analysis of SESAME vacuum system engineering as well as magnets and girder system mechanical designs are described. Multi objective optimization techniques for the storage ring vacuum chambers design from mechanical design point view and the vibration and stability issues for the magnets will be presented.  
 
MOPAN100 Multiple Quadrupole Magnetic Center Alignment on the Girder quadrupole, alignment, laser, storage-ring 395
 
  • L. Tsai
  • T.-C. Fan, C.-S. Hwang, C. J. Lin, S. Y. Perng, D.-J. Wang
    NSRRC, Hsinchu
  Conventional alignments of quadrupole magnets on the girder based on the theodolite and fiducial was limited by human-eye resolution and fiducial precision. The accumulative error of group of magnetic centers may be more than 100 μm. In this paper, an automatic quadrupole magnetic center aligning method was proposed using pulsed wire method to align group of quadrupole magnets concentrically on one girder to higher precision. In order to increase the alignment precision, a short wire reduced sag problem in long wire, laser and position sensitive detector (PSD) system was to trace the wire position to level of micron. The precision of the alignment of quadrupole magnetic centers could be within 30μm. Descriptions of the setup and test results are presented.  
 
MOPAS006 Design and Fabrication of a Multi-element Corrector Magnet for the Fermilab Booster Synchrotron quadrupole, dipole, booster, synchrotron 452
 
  • D. J. Harding
  • J. DiMarco, C. C. Drennan, V. S. Kashikhin, S. Kotelnikov, J. R. Lackey, A. Makarov, A. Makulski, R. Nehring, D. F. Orris, E. Prebys, P. Schlabach, G. Velev, D. G.C. Walbridge
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000.

To better control the beam position, tune, and chromaticity in the Fermilab Booster synchrotron, a new package of six corrector elements has been designed, incorporating both normal and skew orientations of dipole, quadrupole, and sextupole magnets. The devices are under construction and installation at 48 locations is planned. The density of elements and the rapid slew rate have posed special challenges. The magnet construction is presented along with DC measurements of the magnetic field.

 
 
MOPAS016 New Corrector System for the Fermilab Booster controls, booster, quadrupole, dipole 467
 
  • E. Prebys
  • C. C. Drennan, D. J. Harding, V. S. Kashikhin, J. R. Lackey, A. Makarov, W. Pellico
    Fermilab, Batavia, Illinois
  Funding: Work supported under DOE contract DE-AC02-76CH03000.

The Fermilab neutrino program places unprecedented demands on the lab's 8 GeV Booster synchrotron, which has not changed significantly since it was built almost 35 years ago. In particular, the existing corrector system is not adequate to control beam position and tune throughout the acceleration system, and provides limited compensation for higher order resonances. We present an ambitious ongoing project to build and install a set of 48 corrector packages, each containing horizontal and vertical dipoles, normal and skew quadrupoles, and normal and skew sextupoles. Space limitations in the machine have motivated a unique design, which utilizes custom wound coils around a 12 pole laminated core. Each of the 288 discrete multipole elements in the system will have a dedicated power supply, the output current of which is controlled by an individual programmable ramp. This provides for great flexibility in the system, but also presents a challenge in terms of designing the control hardware and software in such a way that the system can be operated in the most efficacious way.

 
 
MOPAS021 Slowly Rotating Coil System for AC Field Measurements of Fermilab Booster Correctors dipole, booster, quadrupole, synchrotron 476
 
  • G. Velev
  • J. DiMarco, D. J. Harding, V. S. Kashikhin, M. J. Lamm, P. Schlabach, M. Tartaglia, J. C. Tompkins
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U. S. Department of Energy

A method for measurement of rapidly changing magnetic fields has been developed and applied to the testing of new room temperature corrector packages designed for the Fermilab Booster Synchrotron. The method is based on fast digitization of a slowly rotating tangential coil probe, with analysis combining the measured coil voltages across a set of successive magnet current cycles. This paper presents results on the field quality measured for normal and skew dipole, quadrupole, and sextupole magnets in several of these corrector packages.

 
 
MOPAS023 Nb3Sn Accelerator Magnet Technology R&D at Fermilab dipole, magnet-design, controls, vacuum 482
 
  • A. V. Zlobin
  • G. Ambrosio, N. Andreev, E. Barzi, R. Bossert, R. H. Carcagno, G. Chlachidze, J. DiMarco, SF. Feher, V. Kashikhin, V. S. Kashikhin, M. J. Lamm, A. Nobrega, I. Novitski, D. F. Orris, Y. M. Pischalnikov, P. Schlabach, C. Sylvester, M. Tartaglia, J. C. Tompkins, D. Turrioni, G. Velev, R. Yamada
    Fermilab, Batavia, Illinois
  Funding: This work was supported by the U. S. Department of Energy

Accelerator magnets based on Nb3Sn superconductor advances magnet operation fields above 10T and increases the coil temperature margin. Development of a new accelerator magnet technology includes the demonstration of main magnet parameters (maximum field, quench performance, field quality, etc.) and their reproducibility using short models, and then the demonstration of technology scale up using long coils. Fermilab is working on the development of Nb3Sn accelerator magnets using shell-type dipole coils and react-and-wind method. As a part of the first phase of technology development Fermilab built and tested six 1-m long dipole models and several dipole mirror configurations. The last three dipoles and two mirrors reached their design fields of 10-11 T. Reproducibility of magnet field quality was demonstrated by all six short models. The technology scale up phase has started by building 2m and 4m dipole coils and testing them in a mirror configuration. This effort complements the Nb3Sn scale up work being performed in the framework of US LHC Accelerator Research Program (LARP). The status and main results of the Nb3Sn accelerator magnet development at Fermilab are reported.

 
 
MOPAS055 Combined Function Magnets Using Double-Helix Coils dipole, quadrupole, multipole, focusing 560
 
  • C. Goodzeit
  • M. J. Ball, R. B. Meinke
    Advanced Magnet Lab., Inc, Melbourne, Florida
  We describe a technology for creating easy-to-manufacture combined function magnets. The field is produced by double-helix coils in which the axial path of the windings is defined by a sinusoidal function containing the superposition of the desired multipoles. The magnitude of the superimposed multipoles relative to the main field can be easily controlled to any level. For example, the combined function winding can contain a quadrupole magnet along with the dipole in an easily manufactured, low cost configuration. An example of a 5 T magnet with a main dipole field and a superimposed quadrupole is shown. We discuss the amplitude of the quadruple component and how it effects the maximum dipole field that can be obtained in the coil. We also show how low level (i.e. 0.1% - 1%) modulation amplitudes of superimposed multipoles can be used as built-in or "free" correction coils to compensate for iron saturation effects or geometrically-induced multipoles. An example is shown for a small bend radius (i.e. 718 mm), 100 mm aperture bent dipole in which the bent-yoke-induced quadrupole harmonic is completely corrected by the modulation function of the double helix turns.

This work is partially supported under U. S. Department of Energy grant : DoE SBIR DE-FG02-06ER 84492

 
 
MOPAS058 A Parallel Controls Software Approach for PEP II: AIDA & Matlab Middle Layer controls, feedback, collider, vacuum 566
 
  • W. Wittmer
  • W. S. Colocho, G. R. White
    SLAC, Menlo Park, California
  Funding: US-DOE

The controls software in use at PEP II had originally been developed in the eighties. The functionality and maturity of the applications in that system have made it very successful in routine operation, but this same longevity and orientation toward fixed requirements, make it largely unsuitable for rapid machine development and ad-hoc online experimentation. A successful recent trend at light sources has been to use the so called MATLAB Middle Layer (MML). This package abstracts each underlying control system framework to which it is connected, such as Channel Access. We describe the middle layer implementation for PEP II and LCLS based on AIDA (described elsewhere in these proceedings), which is unusual in that it provides access to the high level functionality of the legacy control system, as well as to a very large assortment of useful data in addition to channel access read and control. The MML had to be adapted for the implementation at PEP II since colliders differ significantly from light sources by scale and symmetry of the lattice, and PEP II is the first collider at which such an implementation is being done.

 
 
MOPAS090 Overview of the AGS Cold Snake Power Supplies and the new RHIC Sextupole Power Supplies controls, power-supply, extraction, collider 637
 
  • D. Bruno
  • G. Ganetis, W. Louie, J. Sandberg
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract No. DE-AC02-98CH10886 with the U. S. Department of Energy.

The two rings in the Relativistic Heavy Ion Collider (RHIC) were originally constructed with 24 sextupole power supplies, 12 for each ring. Before the start of Run 7, 24 new sextupole power supplies were installed, 12 for each ring. Individual sextupole power supplies are now each connected to six sextupole magnets. A superconducting snake magnet and power supplies were installed in the Alternating Gradient Synchrotron (AGS) and commissioned during RHIC Run 5, and used operationally in RHIC Run 6. The power supply technology, connections, control systems and interfacing with the Quench Protection system for both these systems will be presented.

 
 
TUPMN007 Final Commissioning Results from the Injection System for the Australian Synchrotron Project injection, booster, synchrotron, quadrupole 926
 
  • S. V. Weber
  • F. Bødker, H. Bach, N. Hauge, J. Kristensen, L. K. Kruse, S. P. Møller, S. M. Madsen
    Danfysik A/S, Jyllinge
  • M. J. Boland, R. T. Dowd, G. LeBlanc, M. J. Spencer, Y. E. Tan
    ASP, Clayton, Victoria
  • N. H. Hertel, J. S. Nielsen
    ISA, Aarhus
  Danfysik has delivered a full-energy turn-key injection system for the Australian Synchrotron. The system consists of a 100 MeV linac, a low-energy transfer beamline, a 130 m circumference 3-GeV booster, and a high energy transfer beamline. The booster lattice was designed to have many cells with combined-function magnets (dipole, quadrupole and sextupole fields) in order to reach a very small emittance. The injection system has been commissioned and found to deliver a beam with an emittance of less than 30 nm, and currents in single- and multi-bunch mode in excess of 0.5 and 5 mA, respectively, fulfilling the contractual performance specifications. The repetition frequency is 1 Hz. Results from the commissioning of the system will be presented.  
 
TUPMN057 Design and Tuning of NSRL Undulator UD-1 undulator, radiation, multipole, quadrupole 1055
 
  • Q. K. Jia
  The design, construction, and tuning of the first undulator UD-1 in NSRL are described. The magnetic field design and requirement are given. The results of the magnet blocks measurement and the magnetic field tuning by interchanging magnet blocks are presented.  
 
TUPMN059 The Nonlinear Effects of Fringe Fields in HLS dipole, quadrupole, storage-ring, damping 1061
 
  • L. Wang
  • G. Feng, W. Li, L. Liu, H. Xu
    USTC/NSRL, Hefei, Anhui
  • S. C. Zhang
    USTC, Hefei, Anhui
  As a small low energy electron storage ring, the fringe field effects on linear and nonlinear properties maybe can not be ignored. In this paper, the fringe field of dipole magnets and quadrupole magnets on linear optics parameters and nonlinear driving terms of general purpose operation mode in HLS storage ring were analyzed and calculated. The results showed that, for GPLS mode, the fringe field of dipole and quadrupole is the main source of tune shift with amplitude. The fringe field of dipole contributes non-ignorable part to vertical chromaticity. Similar behavour is also displayed in non linear driving terms.  
 
TUPMN083 Electron Beam Dynamics in 4GLS electron, linac, laser, insertion 1103
 
  • P. H. Williams
  • G. J. Hirst
    STFC/RAL, Chilton, Didcot, Oxon
  • B. D. Muratori, H. L. Owen, S. L. Smith
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Funding: Some of the work reported in this paper is supported by the EuroFEL programme.

Studies of the electron beam dynamics for the 4GLS design are presented. 4GLS will provide three different electron bunch trains to a variety of user synchrotron sources. The 1 kHz XUV-FEL and 100 mA High Average Current branches share a common 540 MeV linac, whilst the 13 MHz IR-FEL must be well-synchronised to them. An overview of the injector designs, electron transport, and energy recovery is given, including ongoing studies of coherent synchrotron radiation, beam break-up and wakefields. This work is being pursued for the forthcoming Technical Design Report due in 2008.

 
 
TUPMN111 A Low Emittance Lattice for the Advanced Light Source emittance, lattice, dynamic-aperture, quadrupole 1170
 
  • H. Nishimura
  • S. Marks, D. Robin, D. Schlueter, C. Steier, W. Wan
    LBNL, Berkeley, California
  Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC03-76SF00098

The possibility exists of achieving significantly lower emittances in an electron storage ring by increasing its horizontal betatron tune. However, existing magnet locations and strengths in a given ring may be inadequate to implement such an operational mode. For example, the ALS storage ring could lower its emittance to one third of the current value by increasing the horizontal tune from 14.25 to 16.25. However, this would come with the cost of large chromaticities that could not be corrected with our existing sextupole magnets. We discuss such operational issues and possible options in this paper.

 
 
TUPMS015 Challenges for the Energy Ramping in a Compact Booster Synchrotron booster, extraction, injection, coupling 1212
 
  • S. F. Mikhailov
  • S. M. Hartman, J. Li, V. Popov, Y. K. Wu
    FEL/Duke University, Durham, North Carolina
  Funding: This work is supported by the US DoE grant #DE-FG02-01ER41175

A booster synchrotron has been recently commissioned at Duke University FEL Laboratory as a part of the High Intensity Gamma-ray Source (HIGS) facility. The booster will provide top-off injection into the storage ring in the energy range of 0.27 - 1.2 GeV. In order to minimize the cost of the project, the booster is designed with a very compact footprint. As a result, unconventionally high field bending magnets at 1.76 T are required. A main ramping power supply drives all dipoles and quadrupoles. Quadrupole trims are used to compensate for tune changes caused by the change of relative focusing strength during ramping. Sextupoles compensate for chromatic effects caused by dipole magnet pole saturation. All these compensations have to be performed as a function of beam energy. Above 1.1 GeV, where the magnets are heavily saturated, the reduction of dynamic aperture is compensated by redistribution of strength among the sextupole families. With these compensations, effects of the magnet saturation do not cause any considerable beam loss during energy ramping.

 
 
TUPMS051 Low Alpha Mode for SPEAR3 lattice, injection, electron, synchrotron 1308
 
  • X. Huang
  • W. J. Corbett, Y. Nosochkov, J. A. Safranek, J. J. Sebek, A. Terebilo
    SLAC, Menlo Park, California
  In the interest of obtaining shorter bunch length for shorter X-ray pulses, we have developed a low-alpha operational mode for SPEAR3. In this mode the momentum compaction factor is reduced by a factor of 21 or more from the usual achromat mode by introducing negative dispersion at the straight sections. We successfully stored 100~mA with the normal fill pattern at a lifetime of 30hrs. The bunch length was measured to be 6.9ps, compared to 17ps in the normal mode. In this paper we report our studies on the lattice design and calibration, orbit stability, higher order alpha measurement, lifetime measurement and its dependence on the sextupoles, injection efficiency and bunch lengths.  
 
TUPAN037 Beam-Beam Simulations for Particle Factories with Crabbed Waist luminosity, simulation, 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 luminosity, resonance, 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, betatron, simulation, luminosity 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.  
 
TUPAN047 Beam-beam Effects in Crab Crossing and Crab Waist Schemes resonance, emittance, betatron, electromagnetic-fields 1493
 
  • K. Ohmi
  • M. E. Biagini, P. Raimondi, M. Zobov
    INFN/LNF, Frascati (Roma)
  • Y. Funakoshi
    KEK, Ibaraki
  To boost up the luminosity performance in B factories, crab crossing and crab waist schemes are proposed. The crab crossing scheme compensates crossing angle, while the crab waist scheme compensates nonlinear tems induced by crossing angle with sextupole magnets. We discuss which nonlinear terms in the beam-beam map are enhanced by the crossing angle and which terms are compensated by the crab waist sextupole.  
 
TUPAN049 Low Emittance Lattices and Final Focus Design for the SuperB Project lattice, emittance, dynamic-aperture, betatron 1499
 
  • Y. Ohnishi
  • M. E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma)
  • Y. Cai, J. Seeman, M. K. Sullivan, U. Wienands
    SLAC, Menlo Park, California
  • A. Wolski
    Liverpool University, Science Faculty, Liverpool
  For the SuperB project* very low emittances (horizontal < 1 nm) and small beta functions at the Interaction Points are required to achieve the design luminosity of 1036/cm2/s. Low emittance lattice have been designed, using the PEP-II magnets, for the two rings of 4 and 7 GeV, which will have the same emittances and damping times. A new Final Focus section has also been designed to get the strong focusing at the Interaction Point, at the same time providing local correction of the high chromaticity and exploiting the large crossing angle and crabbed waist concepts. Lattice features and chromaticity correction schemes will be discussed. Dynamic apertures, with damping wigglers similar to the ILC ones, will also be presented.

* P. Raimondi, "New Developments for SuperB Factories", Invited talk, this Conference

 
 
TUPAN072 Analysis of BEPCII Optics Using Orbit Response Matrix optics, quadrupole, coupling, storage-ring 1544
 
  • Y. Wei
  Funding: Work supported by Core University Program

Due to the errors in all kinds of components of storage ring, the real ring optics is different from the design one. A computer code LOCO is developed to calibrate the linear optics based on the closed orbit response matrix. This paper discusses mainly on the procedure and results of optics correction at BEPCII BPR. Using LOCO, we have determined the errors of quadrupole strengths, BPM gains and corrector kicks, and found the quadrupole strengths that best restore the design optics with sextupoles on. Optics measurement after correction shows the real optics agrees well with the design optics.

weiyy@mail.ihep.ac.cn

 
 
TUPAS017 Tune Drifts on the Tevatron Front Porch dipole, coupling, multipole, quadrupole 1691
 
  • N. M. Gelfand
  Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

Measurements of the tune on the front porch of the Tevatron* showed a drift of the tune which tracked the time dependence of the sextupole moment in the dipoles. Calculations using survey data to calculate the closed orbit failed to reproduce the observed tune shifts. The feed down of these sextupole moments generates a quadrupole field at the ends of the dipoles. It is suggested, based on calculations, that the change in the sextupole moment of the dipoles also produces a change in the strength of the strength of the zero length quadrupole incorporated in the end of the dipoles and that this change can account for the observed tune drifts.

*Tevatron Chromaticity and Tune Drift and Snapshot Studies Report, G. Annala, P. Bauer, M. Martens, D. Still, G. Velev, Beams-doc-1236 (Jan. 5,2005)

 
 
TUPAS031 Analysis of Optics Designs for the LHC IR Upgrade optics, luminosity, 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, luminosity, 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.  
 
TUPAS098 RHIC Beam-Based Sextupole Polarity Verification dipole, optics, injection, quadrupole 1868
 
  • Y. Luo
  • P. Cameron, A. Della Penna, T. Satogata, D. Trbojevic
    BNL, Upton, Long Island, New York
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH10886.

A beam-based method was proposed and applied to check the polarities of the arc sextupoles in the Relativistic Heavy Ion Collider (RHIC) with repetitive local horizontal bumps. Wrong sextupole polarities can be easily identified from mismatched signs and amplitudes of the horizontal and vertical tune shifts from bump to bump and/or from arc to arc. This check takes less than 2 hours for both RHIC Blue and Yellow rings. Tune shifts in both planes during this study were tracked with a high-resolution baseband tunemeter (BBQ) system. This method was successfully used to the sextupole polarity check in the RHIC run06.

 
 
THPMN116 Frequency Map Studies for the ILC Damping Rings lattice, dynamic-aperture, resonance, quadrupole 2987
 
  • I. Reichel
  Funding: This work was supported by the U. S. Department of Energy under Contract No. DE-AC02-05CH11231.

Designing a lattice with sufficient dynamic aperture for the ILC Damping Rings is very challenging as the lattice needs to provide a small equilibrium emittance and at the same time a large aperture for the injected beam including a large momentum acceptance. In addition outside constraints have forced layout changes in the damping ring. Some of the layout changes had an impact on the dynamic aperture. In order to better understand the changes in dynamic aperture, frequency maps are studied. Those studies can help in identifying the reason for the changed dynamic aperture and in finding a good location for the betatron tunes and determining an upper limit for the chromaticities. A summary of recent studies and suggestions improving the dynamic aperture by choosing a different tune are presented.

 
 
THPAN027 The Optimum Chromaticity Correction Scheme for Monochromatic and Non-Monochromatic Beam in HESR lattice, multipole, quadrupole, octupole 3286
 
  • A. N. Chechenin
  • Y. Senichev, N. E. Vasyukhin
    FZJ, Julich
  The High Energy Storage Ring (HESR) of FAIR project consists of two achromatic arcs and two dispersionless straight sections. Due to the multi-functional purpose of the straight sections their contribution into the total chromaticity of the first and second order exceeds the arc's contribution and can affect on the non-monochromatic beam dynamic aperture. We investigate the optimum sextupole and octupole correction scheme for monochromatic and non-monochromatic beam to reach the larger dynamic aperture.  
 
THPAN033 Design Study of the Dipole Magnet for the RHIC EBIS High Energy Transport Line dipole, multipole, quadrupole, simulation 3301
 
  • T. Kanesue
  • M. Okamura, D. Raparia, J. Ritter
    BNL, Upton, Long Island, New York
  • J. Tamura
    Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo
  The design studies of the dipole magnet for EBIS HEBT line is proceeding. The RHIC EBIS is a new high current highly charged heavy ion preinjector for RHIC. The dipole magnet discussed in this paper will be used to guide the beam to existing heavy ion injection line to Booster. A total of 145 degrees bend is provided by two identical dipole magnets with a slit between these magnets to pass only intended charge state ions. Also this magnet has a hole in the side wall to pass the beam from the existing Tandem Van de Graaff. The performance of this magnet calculated by TOSCA and the results of the particle tracking calculation are described.  
 
THPAN039 Space Charge Effects for JPARC Main Ring injection, resonance, space-charge, acceleration 3315
 
  • A. Y. Molodozhentsev
  • T. Koseki, M. Tomizawa
    KEK, Ibaraki
  The JPARC Main Ring should provide the beam power up to 0.8MW at the maximum energy of 50GeV. According to the basic operation scenario during the injection period 8 bunches with the maximum bunch power up to 100kW should be created around the ring. In frame of this report we present the space charge effects in combination with the nonlinear resonances, caused by the machine imperfection, for different beam intensities and different machine operation scenario, including the Main Ring RF system, the collimator system of the RCS-MR beam line and the MR collimation system. The measured field data for main magnets of the ring has been taken into account for this study.  
 
THPAN042 Recent Progress of Optics Correction at KEKB dynamic-aperture, emittance, resonance, optics 3321
 
  • A. Morita
  • H. Koiso, Y. Ohnishi, K. Oide
    KEK, Ibaraki
  In recently KEKB operation, we have to tune the operation parameters during about one week in order to recover the peak performance after the optics correction. This wrong reproducibility of the luminosity is a significant problem for the integrated luminosity of the physics run. In this paper, we present the progress of the optics correction to improve the reproducibility of the machine performance.  
 
THPAN051 Update on the ILC DR Alternative Lattice Design lattice, damping, dynamic-aperture, wiggler 3342
 
  • Y. Sun
  • J. Gao
    IHEP Beijing, Beijing
  • Z. Y. Guo
    PKU/IHIP, Beijing
  In order to reduce the cost for ILC damping rings, an alternative lattice which is different from the baseline configuration design has been designed previously with modified FODO arc cells, and the total quadrupole and sextupole number has been reduced largely, compared with the baseline design. At the same time, to decrease the total cost involved in constructing access shafts needed to supply power, cryogenics etc. for the wigglers and other systems, the number of wiggler sections is decreased from 8 to 4, and further to 2. However, the momentum compaction of this lattice can not be tuned freely. In this paper, a new ILC damping ring lattice design with a variable momentum compaction will be presented, followed by the single particle dynamics associated studies.

*ypsun@ihep.ac.cn

 
 
THPAN088 Optical Effects of Energy Degraders on the Performance of Fragment Separators optics, dipole, target, antiproton 3426
 
  • L. L. Bandura
  • B. Erdelyi
    Northern Illinois University, DeKalb, Illinois
  • J. A. Nolen
    ANL, Argonne, Illinois
  Funding: This work was supported by the U. S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357

An exotic beam facility for the production of rare isotopes requires investigation of higher order optical effects, while taking into account beam-material interactions. An important component of the fragment separator is the absorber wedge, which is necessary for isotope separation. The properties of the absorber, such as the type and shape of material used, determine the resolution and transmission of the fragment separator. Nuclear reactions such as the fission and fragmentation of radioactive isotopes within the target or absorber contribute to the phase space and isotopic distributions of the beam. We have computed these distributions for all isotopes emerging from the target or absorber by implementing a limited fission model from within COSY Infinity that uses polynomial interpolations. Higher order optical aberrations have been computed and successfully eliminated by the shaping of the absorber material. COSY allows us to find the parameters of the absorber that maximize the resolution and transmission of the fragment separator. In addition, beam purity tests have been performed. From our results we have determined an appropriate location for a dump of the primary beam.

 
 
THPAN089 Beam Dynamics, Performance, and Tolerances for Pulsed Crab Cavities at the Advanced Photon Source for Short X-ray Pulse Generation emittance, photon, undulator, radiation 3429
 
  • M. Borland
  • L. Emery, V. Sajaev
    ANL, Argonne, Illinois
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

The Advanced Photon Source (APS) has decided to implement a system using pulsed* crab cavities to produce short x-ray pulses using Zholents'** scheme. This paper describes beam dynamics issues related to implementation of this scheme in a single APS straight section. Modeling of the cavity is used to demonstrate that the deflection will be independent of transverse position in the cavity. Parameters and performance for a standard and lengthened APS straight section are shown. Finally, tolerances are discussed and obtained from tracking simulations.

* M. Borland et al., these proceedings.** A. Zholents et al., NIM A 425, 385 (1999).

 
 
THPAN109 A New Lattice Design for a 1.5 TeV CoM Muon Collider Consistent with the Tevatron Tunnel lattice, collider, dynamic-aperture, quadrupole 3483
 
  • P. Snopok
  • M. Berz
    MSU, East Lansing, Michigan
  • C. Johnstone
    Fermilab, Batavia, Illinois
  A recent effort is underway to design an efficient match of a Muon Collider to the Fermilab site, potentially using the Tevatron tunnel after decommissioning. This work represents a new design for such a collider with emphasis on shortened IR and systematic high-order correction and dynamics studies. With a 1 cm β*, simultaneous control of geometric and chromatic aberrations is critical and can only be achieved through the deliberate addition of nonlinear fields in the Interaction Region itself. This work studies both the correction schemes and the unavoidable impact of high-order correctors – sextupoles, octupoles and even duodecapoles – located in the Interaction Region close to the low-beta quadrupoles or focusing elements. This study proposes and systematically addresses the aberrations for different systems of nonlinear correctors and optimizes performance of an advanced IR.  
 
THPAN113 Mxyzptlk: An Efficient, Native C++ Differentiation Engine quadrupole, simulation 3489
 
  • J.-F. Ostiguy
  • L. Michelotti
    Fermilab, Batavia, Illinois
  Funding: Authored by Universities Research Association, Inc. under contract No. DE-AC02-76CH03000 with the U. S. Department of Energy.

Mxyzptlk was one of the early and, to this day, limited number of differentiation engines implemented by taking full advantage of a language with operator overloading capabilities. It was created with an eye at enabling accelerator related computations, especially within the realm of perturbation theories. Such computations are supported by (1) a one-to-one correspondence between original mathematical abstractions and the data types and operations used to implement them; (2) the exact computation of high order derivatives. Significant efforts were invested recently in modernizing Mxyzptlk both architecturally and algorithmically. Among other things, these substantially improved performance and usabilty. We present a description of the current Mxyzptlk from both standpoints and describe its current capabilities and performance.

 
 
THPAS057 Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps background, coupling, lattice, luminosity 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.

 
 
THPAS062 Recent Progress in a Beam-Beam Simulation Code for Circular Hadron Machines lattice, simulation, beam-beam-effects, storage-ring 3627
 
  • A. C. Kabel
  • W. Fischer
    BNL, Upton, Long Island, New York
  • T. Sen
    Fermilab, Batavia, Illinois
  Over the past years, we have developed a set of codes (PLIBB and NIMZOVICH) applicable to weak-strong and strong-strong beam-beam interactions in hadron machines. We have unified these codes into a single application and augmented the modeled physics to include arbitrary-order magnetic elements, noise sources and wire compensators; algorithmic improvements include diferential-algebraic methods, thick magnetic elements, and a fully-coupled, six-dimensional and symplectic treatment of lumped sections. A novel weighted-macroparticle approach allows for the immediate calculation of very low beam loss rates by particle tracking. The parallelization scheme of the code allows for a highly efficient simulation of colliders with a high number of parasitic crossings and/or pronounced hourglass effect in the IP. Areas of applicability include the LHC and the wire-compensation experiments performed at RHIC. Typical results will be presented.  
 
THPAS103 Design of a Thin Quadrupole to be Used in the AGS Synchrotron quadrupole, multipole, simulation, acceleration 3723
 
  • N. Tsoupas
  • L. Ahrens, R. Alforque, M. Bai, K. A. Brown, E. D. Courant, J. Glenn, H. Huang, A. K. Jain, W. W. MacKay, M. Okamura, T. Roser, S. Tepikian
    BNL, Upton, Long Island, New York
  Funding: Work supported by the US Department of Energy

The AGS synchrotron employs two partial helical snakes* to preserve the polarization of the proton beam during acceleration in the AGS. The effect of the helical snakes on the beam optics is significant at injection energy, with the effect greatly diminishing early in the acceleration cycle. In order to compensate for the effect of the snakes on the beam optics, we have introduced eight compensation quadrupoles in straight sections of the AGS at the proximity of the partial snakes. At injection the strength of these eight quads is set at a high value but ramped down to zero when the effect of the snakes diminishes. Four of the compensation quadrupoles had to be placed in very short straight sections therefore had to be 'thin' with a length of ~30 cm. The 'thin' quadrupoles were laminated and designed to minimize the strength of the dodecoupole harmonic. The thickness of the lamination was also calculated** to keep the ohmic losses generated by the eddy currents in the laminations below an acceptable limit. Comparison of the measured and calculated harmonics will be presented and the ohmic losses due to the eddy currents, as a function of time during rumping will be discussed.

* H. Huang, et al., Proc. EPAC06, (2006), p. 273.** OPERA computer code. Vector Fields Inc.

 
 
FRXAB03 Design, Construction and Commissioning of the SuSI ECR plasma, ion, ion-source, extraction 3766
 
  • P. A. Zavodszky
  • B. Arend, D. Cole, J. DeKamp, G. Machicoane, F. Marti, P. S. Miller, J. Moskalik, W. Nurnberger, J. Ottarson, J. Vincent, X. Wu, A. Zeller
    NSCL, East Lansing, Michigan
  Funding: This work was supported by the National Science Foundation under grant PHY-0110253.

An ECR ion source was constructed at the NSCL/MSU to replace the existing SC-ECRIS. This ECRIS operates at 18+14.5 GHz microwave frequencies and it is planned an upgrade to 24-28 GHz in the second phase of commissioning. A superconducting hexapole coil produces the radial magnetic field; the axial trapping is produced with six superconducting solenoids enclosed in an iron yoke to allow tuning the distance between the plasma electrode and resonant zone in the plasma. The plasma chamber of the ion source can be biased at +30 kV, the beam line at -30 kV. The voltage of the beam line vacuum pipe must be kept constant from the ECRIS to the point of full separation of the beam charge states near the image plane of the analyzing magnet. At this point, an insulator is used to increase the voltage up to zero value. The kinetic energy of the beam is decreased to 30 kV per unit charge after this point, as required for the injection in the Coupled Cyclotron Facility. To decrease the beam divergence, a focusing solenoid is installed after the vacuum pipe break. We report the details of the design, construction and initial commissioning results of this new ECIS.

 
slides icon Slides  
 
FROBAB02 Inhomogeneities in Beams Extracted from ECR Ion Sources ion, ion-source, simulation, plasma 3789
 
  • J. W. Stetson
  • P. S. Spaedtke
    GSI, Darmstadt
  Funding: This work has been supported by National Science Foundation under grant PHY-0110253 and EURONS Contract 506065

An examination of heavy ion beam profiles using viewing targets and CCD cameras at both the GSI and NSCL shows highly structured patterns. These structures generally have a 3-fold symmetry reflecting the highly-magnetized nature of the ion formation within the plasma chamber. A program of experiment and three-dimensional modeling with KOBRA3d is continuing. Results of this program to date are discussed.

 
slides icon Slides  
 
FRPMN011 Studies of Dipole Field Quality for the Beta-Beam Decay Ring dynamic-aperture, dipole, multipole, resonance 3904
 
  • A. Chance
  • J. Payet
    CEA, Gif-sur-Yvette
  Funding: European Community under the FP6 - Research Infrastructure Action - Structuring the European Research Area - EURISOL DS Project Contract no. 515768 RIDS.

The aim of the beta-beams is to produce highly energetic beams of pure electron neutrino and anti-neutrino, coming from beta-decays of the 18Ne10+ and 6He2+, both at γ=100, directed towards experimental halls situated in the Frejus tunnel. The high intensity ion beams are stored in a ring until the ions decay. The beta decay products have a magnetic rigidity different from the one of the parent ions and are differently deflected in the 6T superconducting dipoles. Consequently, all the injected ions are lost anywhere in the ring, generating a high level of irradiation. So, the dipole apertures need to be large enough to avoid the decay products hitting their walls, which may worsen the field quality. A study on its tolerances has been carried out. Since the decay ring has to accept the beam during a large number of turns, the chosen criteria is the size of the dynamic aperture that the multipolar defects in the dipoles may shrink. Tolerances on the systematic and random errors of these defects have been investigated. In order to relax the tolerances, a routine was written which enlarges automatically the dynamic aperture in presence of field errors.

 
 
FRPMN019 The Regular and Random Multi-Pole Errors Influence on the HESR Dynamic Aperture multipole, lattice, quadrupole, octupole 3949
 
  • A. N. Chechenin
  • Y. Senichev, N. E. Vasyukhin
    FZJ, Julich
  The High Energy Storage Ring has the racetrack lattice, where each arc has the even number of super-periods S and the tune with one unit smaller ν=S-1 in both planes. Due to this fundamental feature the total n-order multi-pole is entirely cancelled and the regular errors can be fully compensated inside of one arc. In case of the random multi-pole errors the dynamic aperture is determined by the structure resonances excitation. We consider both regular and random multi-pole influence on the dynamic aperture and the possible correction scheme.  
 
FRPMN022 Analysis of Multi-Turn Beam Position Measurements in the ANKA Storage Ring damping, kicker, storage-ring, electron 3964
 
  • A.-S. Muller
  • I. Birkel, E. Huttel, P. Wesolowski
    FZK, Karlsruhe
  The observation of betatron oscillations following a deflection by a kicker pulse offers the possibility to study various machine parameters. The damping of the centre-of-charge signal's amplitude for one bunch, for example, depends chromaticity, energy loss, momentum compaction factor and impedance. A new multi-turn acquisition system based on LIBERA ELECTRON units (http://www.i-tech.si) has been installed in the ANKA storage ring. First analyses of the thus acquired data for different machine conditions reveal systematic limitations in the current ANKA multi-turn setup. Measurements preformed under varying conditions are presented and discussed with respect to the influence on future analysis.

* http://www.i-tech.si

 
 
FRPMN032 On Skew Nonlinear Resonance in the SPring-8 Storage Ring resonance, coupling, storage-ring, betatron 4003
 
  • M. Takao
  • M. Masaki, J. Schimizu, K. Soutome, S. Takano
    JASRI/SPring-8, Hyogo-ken
  Recently we accomplish the matrix formulation for the canonical perturbation theory of the linear betatron coupling resonance. By merging the perturbation theory with the matrix formalism, we manifest the symplectic structure of the former theory, and conversely derive the analytical representation for the latter. The formulation for the coupled betatron motion implies that the linear coupling causes the excitation of skew resonances by nonlinear fields with mid-plane symmetry. This effect is visible in the vicinity of the linear coupling resonance, which is observed in the SPring-8 storage ring, for example, as the blow-up of the vertical beam size on the third order skew coupling resonance. For the purpose of studying the impacts of the skew nonlinear resonance on the beam dynamics, we investigate the characteristic behavior of the resonance expected by the matrix formulation.  
 
FRPMN036 Resonance Correction systems for JPARC Main Ring resonance, quadrupole, coupling, injection 4024
 
  • A. Y. Molodozhentsev
  • T. Koseki, M. Tomizawa
    KEK, Ibaraki
  • S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  The injection time for the JPARC Main Ring for the basic scenario is about 120ms, which corresponds to about 20,000 turns. The particle losses at the Main Ring collimator should be less than 1% from the expected maximum beam power at the injection energy. To keep the particle losses for the Main Ring operation below the limit, the correction systems have been suggested to eliminate possible resonance excitation. The proposed correction schemes allow us to suppress linear and nonlinear resonances. The calculated and/or measured field data for main magnets of the ring has been taken into account for this study.  
 
FRPMS015 Correction of Second Order Chromaticity at Tevatron betatron, quadrupole, resonance, injection 3922
 
  • A. Valishev
  • G. Annala, V. A. Lebedev, R. S. Moore
    Fermilab, Batavia, Illinois
  Correction of the second order betatron tune chromaticity is essential for operation at the working point near half integer resonance which is proposed as one of the ways to improve performance of the Tevatron. In this report the new chromaticity correction scheme with split sextupole families is described. Details of implementation and commissioning at the present working point are discussed.  
 
FRPMS018 1-MeV Electrostatic Ion Energy Analyzer ion, space-charge, quadrupole, diagnostics 3940
 
  • F. M. Bieniosek
  • M. Leitner
    LBNL, Berkeley, California
  Funding: Work performed under the auspices of the U. S. Department of Energy by the university of California, Lawrence Berkeley National Laboratory under Contract No. DE-AC03-76F00098.

We describe a high resolution (a few x 10-4) 90-degree cylindrical electrostatic energy analyzer for 1-MeV (singly ionized) heavy ions for experiments in the Heavy Ion Fusion Science Virtual National Laboratory. By adding a stripping cell, the energy reach of the analyzer is extended to 2 MeV. This analyzer has high dispersion in a first-order focus with bipolar deflection-plate voltages in the range of ±50 kV. We will present 2- and 3-D calculations of vacuum-field beam trajectories, space-charge effects, field errors, and a multipole corrector. The corrector consists of 12 rods arranged in a circle around the beam. Such a corrector has excellent properties as an electrostatic quadrupole, sextupole, or linear combination. The improved energy diagnostic allows measurements of beam charge state and energy spread, such as caused by charge exchange or temperature anisotropy, and better understanding of experimental results in longitudinal beam studies.

 
 
FRPMS026 Strong-Strong Simulation of Long-Range Beam-Beam Effects at RHIC emittance, resonance, betatron, simulation 3979
 
  • J. Qiang
  • W. Fischer
    BNL, Upton, Long Island, New York
  • T. Sen
    Fermilab, Batavia, Illinois
  Funding: This work was supported by the U. S. Department of Energy under Contract no. DE-AC02-05CH11231.

Long-range beam-beam interactions can cause significant degrade of beam quality and lifetime in high energy ring colliders. At RHIC, a series of experiments were carried out to study these effects. In this paper, we report on numerical simulation of the long-range beam-beam interactions at RHIC using a parallel strong-strong particle-in-cell code, BeamBeam3D. The simulation includes nonlinearities from both the beam-beam interactions and the arc sextupoles. We observed significant emittance growth for beam separation below 4 σs under nominal tunes. A scan study in tune space shows strong emittance growth around 7th order resonance. Including the tune modulation due to chromaticity and synchrotron motion shows larger emittance growth than the case without the tune modulation.

 
 
FRPMS060 Commissioning of the UCLA Neptune X-Band Deflecting Cavity and Applications to Current Profile Measurement of Ramped Electron Bunches electron, plasma, linac, laser 4135
 
  • R. J. England
  • D. Alesini
    INFN/LNF, Frascati (Roma)
  • B. D. O'Shea, J. B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  Funding: Department of Energy Grant # DE-FG02-92ER40693

A 9-cell standing wave deflecting cavity has recently been constructed and installed at the UCLA Neptune Laboratory for use as a temporal diagnostic for the 13 MeV, 300 to 700 pC electron bunches generated by the Neptune photoinjector beamline. The cavity is a center-fed Glid-Cop structure operating in at TM110-like deflecting mode at 9.59616 GHz with a pi phase advance per cell. At the maximum deflecting voltage of 500 kV, the theoretical resolution limit of the device is 50 fs, although with current beam parameters and a spot size of 460 microns RMS the effective resolution is approximately 400 fs. We discuss the operation and testing of the cavity as well as its intended application: measuring the temporal current profile of ramped electron bunches generated using the Neptune dogleg compressor, and we present the first measurements of the electron beam current profile obtained using the deflecting cavity.

 
 
FRPMS084 Detection of Instumental Drifts in the PEP II LER BPM System feedback, controls, optics, pick-up 4261
 
  • W. Wittmer
  • A. S. Fisher, D. J. Martin, J. J. Sebek
    SLAC, Menlo Park, California
  Funding: US-DOE

During the last PEP-II run a major goal was to bring the Low-Energy Ring optics as close as possible to the design. Sudden artificial jumps of the orbit, which were regularly observed by a large number of BPMs during routine operation, were interfering with this effort. The source of the majority of these jumps had been traced to the filter-isolator boxes (FIBs) near the BPM buttons. A systematic approach to find and repair the failing units had been developed and implemented. Despite this effort, the instrumental orbit jumps never completely disappeared. To trace the source of this behavior a test setup, using a spare Bergoz MX-BPM processor (kindly provided by SPEAR III at SSRL) was connected in parallel to various PEP-II BPM processors. In the course of these measurements a slow instrumental orbit drift was found which was clearly not induced by a moving positron beam. Based on the size of the system and the limited time before the end of PEP II an accelerator improvement project was initiated to install BERGOZ BPM-MX processors close to all sextupoles.

 
 
FRPMS097 Realistic Non-linear Model and Field Quality Analysis in RHIC Interaction Regions dipole, multipole, quadrupole, interaction-region 4309
 
  • J. Beebe-Wang
  • A. K. Jain
    BNL, Upton, Long Island, New York
  Funding: Work performed under the United States Department of Energy Contract No. DE-AC02-98CH1-886.

The existence of multipolar components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. So, a realistic non-linear model is crucial for understanding the beam behavior and to achieve the ultimate performance in RHIC. A procedure is developed to build a non-linear model using the available multipolar component data obtained from measurements of RHIC magnets. We first discuss the measurements performed at different stages of manufacturing of the magnets in relation to their current state in RHIC. We then describe the procedure to implement these measurement data into tracking models, including the implementation of the multipole feed down effect due to the beam orbit offset from the magnet center. Finally, the field quality analysis in the RHIC interaction regions is presented.

 
 
FRPMS099 The Poincare Map, Lie Generator, Nonlinear Invariant, Parameter Dependance, and Dynamic Aperture for Rings lattice, controls, optics, dynamic-aperture 4315
 
  • J. Bengtsson
  Funding: Work supported by U. S. DOE, Contract No. DE-AC02-98CH10886.

In earlier work related to the NSLS-II project we have outlined a control theory approach for the dynamic aperture problem. In particular, an algorithm for the joint optimization of the Lie generator and the working point for the Poincare map. This time we report on how the Lie generator provides guidelines on acceptable magnitudes for e.g. the intrinsic nonlinear effects from insertion devices, and the nonlinear pseudo-invariant can be used to optimize the dynamic aperture. We also show how a polymorphic beam line class can be used to study the parameter dependance and rank conditions for control of optics and dynamic aperture.

bengtsson@bnl.gov

 
 
FRPMS109 Measurement and Correction of Third Resonance Driving Term in the RHIC resonance, dipole, betatron, proton 4351
 
  • Y. Luo
  • M. Bai, J. Bengtsson, R. Calaga, W. Fischer, N. Malitsky, F. C. Pilat, T. Satogata
    BNL, Upton, Long Island, New York
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH10886.

To further improve the polarized proton (pp) run collision luminosity in the Relativistic Heavy Ion Collider, correction of the horizontal two-third resonance is desirable to increase the available tune space. The third resonance driving term (RTD) is measured with the turn-by-turn (TBT) beam position monitor (BPM) data with AC dipole excitation. A first order RTD response matrix based on the optics model is used to on-line compensate the third resonance driving term h30000 while keeping other first order RTDs and first order chromaticities unchanged. The results of beam experiment and simulation correction are presented and discussed.

 
 
FRPMS110 Online Nonlinear Chromaticity Correction Using Off-Momentum Tune Response Matrix optics, simulation, dipole, betatron 4357
 
  • Y. Luo
  • W. Fischer, N. Malitsky, S. Tepikian, D. Trbojevic
    BNL, Upton, Long Island, New York
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH10886.

With 8 arc sextupole families in each RHIC ring, the nonlinear chromaticities can be corrected on-line by matching the off-momentum tunes onto the wanted off-momentum tunes with linear chromaticity only. The Newton method with singular value decomposition (SVD) technique is used for this multi-dimensional nonlinear optimization, where the off-momentum tune response matrix with respect to sextupole strength changes is adopted to simplify and fasten the on-line optimization process. The off-momentum tune response matrix can be calculated with the on-line accelerator optics model or directly measured with the real beam. This correction method will be verified and used in the coming RHIC run'07.

 
 
FRPMS111 Dynamic Aperture Evaluation at the Current Working Point for RHIC Polarized Proton Operation dynamic-aperture, resonance, multipole, dipole 4363
 
  • Y. Luo
  • M. Bai, J. Beebe-Wang, W. Fischer, A. K. Jain, C. Montag, T. Roser, S. Tepikian, D. Trbojevic
    BNL, Upton, Long Island, New York
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH10886.

To further improve the the polarized proton (pp) luminosity in the Relativistic Heavy Ion Collider, the beta functions at the two interaction points (IPs) will be reduced from 1.0 m to 0.9m in 2007. In addition, it is planned to increase the bunch intensity from 1.5*1011 to 2.0*1011. To accommodate these changes, the nonlinear chromaticities and the third resonance driving term should be corrected. In 2007, the number of the arc sextupole power supplies will be doubled from 12 to 24, which allows nonlinear chromaticity correction. With the updated field errors in the interaction regions (IRs), detailed dynamic aperture studies are carried out to optimize the nonlinear correction schemes, and increase the available tune space in collision.