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betatron

  
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MOPCH062 Centroid, Size, and Emittance of a Slice in a Kicked Bunch synchrotron, emittance, radiation, photon 172
 
  • C.-X. Wang, W. Guo
    ANL, Argonne, Illinois
  A transversely kicked bunch will decohere due to, among other things, chromatic and amplitude-dependent tune shifts. The chromatic tune shift leads to correlation between transverse and longitudinal phase space. Such a correlation can be used for compressing synchrotron radiation of the bunch with adequate optics. In this report, we revise the decoherence calculation to derive the centroid and second moments of a beam slice in a kicked bunch, taking into account chromatic and nonlinear decoherence, but neglecting wakefield and radiation damping, etc. A simple formula for estimating slice bunch length (and potential pulse compression ratio) is given for the ideal situation.  
 
MOPLS029 Preliminary Study of a Crab Crossing System for DAFNE luminosity, coupling, damping, simulation 607
 
  • A. Gallo, D. Alesini, F. Marcellini, P. Raimondi, M. Zobov
    INFN/LNF, Frascati (Roma)
  The implementation of a crab crossing scheme at the Frascati Phi-factory DAFNE is under consideration, together with several other ideas and upgrades to increase the collider luminosity. The crab crossing is beneficial to the luminosity because it is expected to optimize the geometrical superposition of the colliding bunches and to weaken the synchro-betatron beam-beam resonances. The basic specifications of such a system, the expected luminosity increase, a preliminary design of the crab cavities and the architecture of the dedicated RF system are presented.  
 
MOPLS074 Collimation Optimisation in the Beam Delivery System of the International Linear Collider collimation, lattice, linear-collider, collider 721
 
  • F. Jackson
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  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 is developed to improve the performance of the BDS collimation system. Primary considerations are the phase relationships between collimation systems and the final focus, and the overall bandwidth of the system.  
 
MOPLS096 Effects of Wake Fields in the CLIC BDS CLIC, luminosity, quadrupole, emittance 780
 
  • G. Rumolo, A. Latina, D. Schulte
    CERN, Geneva
  The wake fields due to collimators in the Beam Delivery System of CLIC are modeled using a conventional approach. According to the chosen ranges of parameters, differences in the transverse kicks due to both the geometric and resistive wall components for different regimes are highlighted (inductive or diffractive for the geometric wake fields, short- or long-range, ac or dc for the resistive wall wake fields). A module for particle tracking along the BDS including the effect of wake fields has been introduced in PLACET, and the first tracking results are shown.  
 
TUPCH044 Turn-by-turn Data Acquisition and Post-processing for the Diamond Booster and Storage Ring booster, storage-ring, DIAMOND, injection 1103
 
  • R. Bartolini, M.G. Abbott, I.P.S. Martin, G. Rehm, J.H. Rowland
    Diamond, Oxfordshire
  The Diamond booster and storage ring are equipped with Libera Electron Beam Position Processors with turn-by-turn capabilities. We describe here the turn-by-turn data acquisition system and the software used for post-processing the beam data. The signals from the Libera boxes are acquired and controlled with EPICS and then transferred to the MATLAB environment via the MATLAB Channel Access. Here they are post-processed using MATLAB capabilities and dedicated software linked to MATLAB. Examples of data acquired and measurements performed during Diamond booster and storage ring commissioning are reported.  
 
TUPCH052 Turn by Turn Measurements at DAFNE Based on the Libera Beam Position Processor pick-up, injection, kicker, controls 1124
 
  • A. Stella, M. Serio
    INFN/LNF, Frascati (Roma)
  The BPM detection electronics developed by Instrumentation Techonologies implements digital receivers technology to measure beam position from the amplitude of pick-up signals. Besides the closed orbit mode, the Libera module can be operated also in the Turn-by-Turn mode. Operational experience with Libera at DAFNE, the Frascati e+ e- collider, has been focused on this functionality. Data obtained from DAFNE have been processed with well established extraction algorithms to accurately measure the betatron tunes from a small number of turns, providing instantaneous information on tune variations occurred also in fast damped decays after a kick. Hardware and software implementation together with experimental data are reported.  
 
TUPCH063 Novel Method for Beam Dynamics using an Alpha Particle Source simulation, injection, closed-orbit, lattice 1157
 
  • A. Sato, M. Aoki, Y. Arimoto, I. Itahashi, Y. Kuno, T. Oki, M. Yoshida
    Osaka University, Osaka
  PRISM is a future muon source which would provide high intense, monochromatic and pure muon beams. In order to achieve such muon beams we use a technique called Phase Rotation using an FFAG ring (PRISM-FFAG). The PRISM-FFAG ring is now under construction in Osaka university. The Commissioning will start in JFY 2007. In order to investigate the dynamical performances of the FFAG before the actual commissioning, we propose a novel experimental method. The principle of the method and its application to PRISM-FFAG will be described in this paper.  
 
TUPCH073 Study of Beam Energy Spread at the VEPP-4M diagnostics, synchrotron, collider, scattering 1178
 
  • O.I. Meshkov, V. F. Gurko, A.D. Khilchenko, V. Kiselev, N.Yu. Muchnoi, A.N. Selivanov, V.V. Smaluk, A. N. Zhuravlev
    BINP SB RAS, Novosibirsk
  The knowledge of beam energy spread is necessary for the experimental program of the VEPP-4M collider. In this report we discuss the application of optical diagnostics for measurement of this value. The diagnostics is based on multi-anode photomultiplier and provides information about betatron and betetron frequencies of electron beam*. The beam energy spread is derived from the spectra of synchrotron oscillation. The results, obtained with this method, are compared with data, provided by Compton backscattering technique.

*O. I. Meshkov et al. Application of the beam profile monitor for VEPP-4M tuning. Proc. of DIPAC '05, June 6 - 8, 2005, Lyon, France, POM008.

 
 
TUPCH098 Antiproton Momentum Distributions as a Measure of Electron Cooling Force at the Fermilab Recycler electron, antiproton, emittance, scattering 1241
 
  • D.R. Broemmelsiek, S. Nagaitsev
    Fermilab, Batavia, Illinois
  The Fermilab Recycler is a fixed 8GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel near the ceiling. Electron cooling of high-energy antiprotons has recently been demonstrated at the Recycler. Antiproton beam Schottky signals were used to measure the antiproton momentum distribution at equilibrium between a calibrated broadband diffusion source and electron cooling. The large Recycler momentum aperture, the dependence of the electron cooling force as a function of the antiproton momentum deviation and the calibrated diffusion source combine to give a unique spectral measurement of the antiproton momentum beam distribution.  
 
TUPLS001 Enhanced Optical Cooling of Ion Beams for LHC ion, undulator, kicker, pick-up 1483
 
  • E.G. Bessonov, M.V. Gorbunkov
    LPI, Moscow
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  Enhanced optical cooling (EOC) of fully stripped lead ions in LHC is investigated. The method of EOC is based on the usage of pickup and kicker undulators and optical amplifier. External selectivity is arranged by a moving screen located on the image plane of the optical system, projecting the emitted undulator radiation there (see physics/0509196). Nonlinear features of cooling and requirements to the ring lattice, optical and laser systems are discussed. Comparison with classical optical stochastic cooling (OSC) is represented as well.  
 
TUPLS018 Collimation Efficiency during Commissioning collimation, LHC, proton, insertion 1529
 
  • C.B. Bracco, R.W. Assmann, A. Ferrari, S. Redaelli, G. Robert-Demolaize, M. Santana-Leitner, V. Vlachoudis, Th. Weiler
    CERN, Geneva
  The design of the LHC collimation system naturally focused on understanding and maximizing the ultimate performance with all collimators in place. However, for the commissioning of the LHC it is important to analyze the collimation efficiency with certain subsets of collimators, with increased collimation gaps and relaxed set-up tolerances. Special studies on halo tracking and energy deposition have been performed in order to address this question. The expected cleaning performance and intensity limits are discussed for various collimation scenarios as they might be used during commissioning and initial operation of the LHC.  
 
TUPLS025 Racetrack Non-scaling FFAG for Muon Acceleration acceleration, lattice, focusing, linac 1544
 
  • D. Trbojevic
    BNL, Upton, Long Island, New York
  The non-scaling Fixed-Field Alternating Gradient (FFAG) machines have very strong focusing, large momentum acceptance, and small dispersion and betatron functions. This report is a study of using a compact non-scaling FFAG in combination with the superconducting linac to accelerate the muons. The drift space between two kinds of combined function magnets in the previous non-scaling FFAG is removed. The time of flight in the non-scaling FFAG has a parabolic dependence on momentum. The large energy acceptance of the machine requires matching between the linac and the non-scaling FFAG arcs for both the betatron and dispersion functions over the entire energy range.  
 
TUPLS070 Chromaticity Control in Linear-field Nonscaling FFAGs by Sextapoles quadrupole, focusing, lattice, LEFT 1657
 
  • S.R. Koscielniak
    TRIUMF, Vancouver
  Because of their high repetition rate and large apertures, FFAGs are proposed for high-current medical accelerators suitable for cancer therapy. The linear-field nonscaling FFAG is made from repeating cells containing D and F combined function magnets. The betatron tune profiles decrease with momentum; this leads to the crossing of resonances. We examine how sextapole magnets may be used to flatten the tune profile; in particular (i) whether it is better to place them at the D or F; (ii) what strength is required; and (iii) what is their effect on the closed orbits and path length? The orbit geometry is derived from a thin-element model and the tunes from power series in the quadrupole strength. Chromaticity is corrected by coupling focusing strength to dispersion, which is far stronger in the F element. The zeros of the orbit dispersion become the poles of the "sextapole strength to flatten the tune at some particular momentum". We demonstrate that a weak F sextapole can produce a substantial horizontal tune flattening, and has little impact on other optical properties. Contrarily, placing the sextapole at the D element may destroy the dynamic aperture and or vertical focusing.  
 
TUPLS073 Formulae for Linear-field Non-scaling FFAG Accelerator Orbits lattice, proton, ion, resonance 1666
 
  • M.K. Craddock
    UBC & TRIUMF, Vancouver, British Columbia
  • S.R. Koscielniak
    TRIUMF, Vancouver
  Non-scaling FFAG accelerators using constant-gradient F and D magnets with their fields decreasing outwards can compact ion orbits for a wide range of momentum (e.g., 1:2) into a narrow radial range. Designs to accelerate protons, ions and muons are currently being studied for proton drivers, cancer therapy facilities and neutrino factories. In this paper, analytic formulae are reported for some basic orbit properties, helping to make clear their dependence on the various design parameters and momentum. For the designs tested so far the numerical results are in excellent agreement with those obtained using lattice codes.  
 
WEXFI03 Non-linear Collimation in Linear and Circular Colliders collimation, sextupole, optics, collider 1892
 
  • A. Faus-Golfe
    IFIC, Valencia
  • J. Resta-López, F. Zimmermann
    CERN, Geneva
  We describe the concept on nonlinear collimation of beam halo in linear and circular colliders. In particular we present the application of such a concept in two different cases: the energy collimation system for CLIC at 3 TeV c.m. energy and a betatron collimation system for LHC at 14 TeV c.m. energy. For each case, the system properties, like chromatic bandwidth, collimator survival and cleaning efficiency, are evaluated and compared with those of the corresponding linear collimation system.  
slides icon Transparencies
 
WEOFI01 Beam Dynamics Measurements in the Vicinity of a Half-integer Resonance emittance, resonance, beam-beam-effects, radiation 1902
 
  • T. Ieiri, J.W. Flanagan, H. Fukuma, H. Ikeda, Y. Ohnishi, K. Oide, M. Tobiyama
    KEK, Ibaraki
  The operating point of the betatron tune set near a half-integer is a crucial parameter to make high luminosity in electron/positron ring colliders. Dynamic beam-beam effects would change the optics parameters of the colliders, depending on the betatron tune and the beam-beam parameter. On the other hand, existence of the half-integer stopband makes the beam unstable. Therefore, beam behavior near a half-integer might provide interesting issues from the viewpoint of beam dynamics. We measured a frequency response of the beam across a half-integer for measuring the betatron tune at KEKB. A sharp spike just at a half-integer was observed in the tune spectrum. We believe that the spectrum would be a nonlinear resonance caused by some off-momentum particles in a bunch, not by a coherent motion of a whole bunch. The horizontal beam size measured using a synchrotron radiation monitor indicated a slight increase when the tune approached a half-integer. The variations in the beam size are discussed, considering both dynamic beam-beam effects and a beta beat due to the half-integer stopband.  
slides icon Transparencies
 
WEPCH012 Comparison of Betatron Function Measurement Methods and Consideration of Hysteresis Effects quadrupole, optics, storage-ring, injection 1945
 
  • O. Kopitetzki, D. Schirmer, G. Schmidt, K. Wille
    DELTA, Dortmund
  Two methods for determining the betatron functions in a storage ring were used to survey the linear optics at Delta. The fast orbit response analysis is used to gain betatron functions at the beam position monitors (BPMs) and dipole correctors. These are compared to betatron functions measured by the tune scan method which gives the beta functions in the quadrupoles. To improve the accuracy of the betatron functions obtained by the tune scan method a measuring procedure is introduced which considers the hysteresis effects in the quadrupole magnets. Systematic deviations in the beta functions measured between the two methods have been observed. The calibration errors of the BPMs can explain the observed deviations. With the orbit response analysis also the betatron phase advances between the measurement points can be calculated. Because these do not depend on the calibration errors, unlike the betatron functions, the differences between measurement and model can be determined more precise. A comparison of both methods with the optics model will be presented.  
 
WEPCH024 Matrix Formulation for Hamilton Perturbation Theory of Linearly Coupled Betatron Motion resonance, coupling, lattice, storage-ring 1975
 
  • M. Takao
    JASRI/SPring-8, Hyogo-ken
  Linear coupled motion in a circular accelerator was successfully parametrized through the transfer matrix approach, where normal mode Twiss and coupling parameters are defined as an extension of Courand and Snyder formulation. However it is not straightforward to assign analytical expressions to the coupling parameters. On the other hand the coupled motion was analytically solved by the Hamilton perturbation theory, which ingeniously describes the resonance phenomena. In the perturbation theory, however, the symplectic structure of the coupled motion is obscure in turn. Hence, for the purpose of combining both the theories with each other with keeping the respective virtues, we develop the matrix formulation based on the Hamilton perturbation theory. Since we have already known the solution of equation of motion, we can construct the transfer matrix in terms of the solution. Thus we formulate the betatron motion with linear coupling resonance in analytic and symplectic manner. As an application of the formulation, we investigate the two-dimensional beam ellipse in an electron storage ring.  
 
WEPCH026 Recent Progress of Optics Measurement and Correction at KEKB optics, sextupole, KEKB, closed-orbit 1981
 
  • A. Morita, H. Koiso, Y. Ohnishi, K. Oide
    KEK, Ibaraki
  We present the progress of the optics measurement and the correction scheme of the KEKB operation for example off-momentum beta correction.  
 
WEPCH028 Position Shuffling of the J-PARC Main Ring Magnets sextupole, quadrupole, resonance, lattice 1984
 
  • M. Tomizawa, K. Fan, S. Igarashi, K. Ishii, H. Kobayashi, A.Y. Molodozhentsev, K. Niki, E. Yanaoka
    KEK, Ibaraki
  • Y. Irie
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Machida
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  The J-PARC 50GeV main ring has 96 dipole, 216 quadrupole with 11 families and 72 sextupole magnets with 3 families. Magnets installation in the tunnel started last year and will be planed to finish by the end of next fiscal year. Field measurements of all magnets will soon finish by this March. Deviations for BL, B'L, B"L in dipole, quadrupole and sextupole magnets make COD, beta beat and third integer stopband, respectively. They can be reduced by choosing a pair of magnets with similar field deviation and by positioning them so as to cancel each other considering betatron phase (shuffling). In this paper, we will report our shufflling scheme chosen under the given schedule for installation and field measurements and also will show performances expected by the shufflings.  
 
WEPCH038 Nonlinear Characteristics of the TME Cell emittance, resonance, sextupole, lattice 2002
 
  • V.A. Kvardakov, E. Levichev
    BINP SB RAS, Novosibirsk
  The TME (Theoretical Minimum Emittance) cell is being used now for designing the lattice of different storage rings (SR sources, damping rings, FFAG accelerators, etc.). Strong sextupoles required to correct the natural chromaticity of the lattice reduce the dynamic aperture. In the paper we consider the main features of the nonlinear perturbation strength and its connection with the essential lattice parameters: horizontal emittance, betatron tunes, and natural chromaticity. The analytical results are compared with the computer simulation.  
 
WEPCH050 Correction of Vertical Dispersion and Betatron Coupling for the TPS Storage Ring emittance, coupling, quadrupole, sextupole 2032
 
  • H.-J. Tsai, H.-P. Chang, P.J. Chou, C.-C. Kuo, G.-H. Luo, M.-H. Wang
    NSRRC, Hsinchu
  A proposed 3 GeV Taiwan Photon Source (TPS) is a low emittance (1.7 nm-rad) medium energy storage ring with 24 DBA cells. The vertical emittance due to betatron coupling and spurious vertical dispersion generated by the magnet errors and off-center orbits in sextupoles and quadrupoles are analyzed. The sensitivities due to magnetic alignment errors are estimated. Using the SVD method, the result of global vertical dispersion and betatron coupling correction is presented.  
 
WEPCH062 Precision Measurement and Improvement of Optics for e+, e- Storage Rings optics, coupling, lattice, quadrupole 2065
 
  • Y.T. Yan, Y. Cai, W.S. Colocho, F.-J. Decker, J. Seeman, M.K. Sullivan, J.L. Turner, U. Wienands, M. Woodley, G. Yocky
    SLAC, Menlo Park, California
  Through horizontal and vertical excitations, we have been able to make a precision measurement of linear geometric optics parameters with a Model-Independent Analysis (MIA). We have also been able to build up a computer model that matches the real accelerator in linear geometric optics with an SVD-enhanced Least-square fitting process. Recently, with the addition of longitudinal excitation, we are able to build up a computer virtual machine that matches the real accelerators in linear optics including dispersion without additional fitting variables. With this optics-matched virtual machine, we are able to find solutions that make changes of many normal and skew quadrupoles for machine optics improvement. It has made major contributions to improve PEP-II optics and luminosity. Examples from application to PEP-II machines will be presented.  
 
WEPCH076 Renormalization Group Reduction of the Frobenius-Perron Operator resonance, sextupole, lattice, storage-ring 2095
 
  • S.I. Tzenov
    Universita' degli Studi di Salerno, Dipartimento di Fisica E.R. Caianiello, Baronissi
  The Renormalization Group (RG) method is adopted as a tool for a constructive analysis of the properties of the Frobenius-Perron Operator. The renormalization group reduction of a generic symplectic map in the case, where the unperturbed rotation frequency of the map is far from structural resonances driven by the kick perturbation has been performed in detail. It is further shown that if the unperturbed rotation frequency is close to a resonance, the reduced RG map of the Frobenius-Perron operator (or phase-space density propagator) is equivalent to a discrete Fokker-Planck equation for the renormalized distribution function. The RG method has been also applied to study the stochastic properties of the standard Chirikov-Taylor map.  
 
WEPCH078 Measurement of Wake Effects by Means of Tune Shift in the KEKB Low-Energy Ring electron, positron, single-bunch, KEKB 2101
 
  • T. Ieiri, H. Fukuma, Y. Ohnishi, M. Tobiyama
    KEK, Ibaraki
  The electron cloud produced by the positron beam induces single-bunch and coupled-bunch wakes, in addition to a tune shift. Effects of the dipole wake-field including the electron cloud were tried to measure in the KEKB Low Energy Ring. A test bunch was placed behind a bunch-train of the positron beam, even though a test bunch itself might interact with the remaining electron cloud. We measured a current-dependent tune-shift of a test bunch under constant train-current, while changing the bucket position of a test bunch. The tune shift indicated a strong defocusing field, however, tended to a focusing field when a test bunch approached a train with high train-current. The results are discussed, considering variations of the electron cloud density.  
 
WEPCH085 Algorithms for Chromatic Sextupole Optimization and Dynamic Aperture Increase sextupole, dynamic-aperture, lattice, storage-ring 2116
 
  • E. Levichev, P.A. Piminov
    BINP SB RAS, Novosibirsk
  Strong chromatic sextupoles compensating natural chromaticity of a storage ring may reduce dynamic aperture drastically. In the case of several sextupole families, one can find a lot of ways to correct chromaticity, which provides different sizes of the dynamic aperture. Finding a solution that gives the largest dynamic aperture is an important task for the storage ring design and operation. The paper discusses several approaches to sextupole arrangement optimization in order to obtain a large dynamic aperture.  
 
WEPCH086 Adiabatic Theory of Slow Extraction of Particles from a Synchrotron resonance, synchrotron, extraction, heavy-ion 2119
 
  • S.A. Nikitin
    BINP SB RAS, Novosibirsk
  An analytical approach is developed to describe the process of slow extraction of particles from a synchrotron based on adiabatic crossing of the betatron resonance of the third order. An exact expression for the phase integral is found to analyze the conditions of oscillation amplitude growth near the resonance band. It allows one to directly define the interval of adiabatic motion from the start of decreasing the resonant tune to the beginning of fast increase of the oscillation amplitude. The interval distribution function is constructed for the cases of zero momentum spread and zero machine chromaticity as well as for the general case, taking into account non-zero momentum spread, non-zero chromaticity and synchrotron oscillations. Some numeric calculations of the time dependence of the extracted particle current are presented. It is shown that the momentum spread in the extracted beam can be minimized with the use of additional RF acceleration of particles during the slow extraction procedure.  
 
WEPCH100 Application of the Lie-transform Perturbation Theory for the Turn-by-turn Data Analysis resonance, coupling, optics, lattice 2146
 
  • Y. Alexahin
    Fermilab, Batavia, Illinois
  Harmonic analysis of turn-by-turn BPM data is a rich source of information on linear and nonlinear optics in circular machines. In the present report the normal form approach first introduced by R. Bartolini and F. Schmidt is extended on the basis of the Lie-transform perturbation theory to provide direct relation between the sources of perturbation and observable spectra of betatron oscillations. The goal is to localize strong perturbing elements, find the resonance driving terms - both absolute value and phase - that are necessary for calculation of the required adjustments in correction magnet circuits: e.g. skew-quadrupoles for linear coupling correction. The theory is nonlinear and permits to analyze higher order effects, such as coupling contribution to beta-beating and nonlinear sum resonances.  
 
WEPCH128 Virtual Accelerator as an Operation Tool at J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) simulation, synchrotron, optics, feedback 2224
 
  • H. Harada, K. Shigaki
    Hiroshima University, Higashi-Hiroshima
  • K. Furukawa
    KEK, Ibaraki
  • H. Hotchi, F. Noda, H. Sako, H. Suzuki
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Machida
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  We developed a virtual accelerator based on EPICS for 3 GeV Rapid-Cycle Synchrotron (RCS) in J-PARC. It is important to have an on-line model of optics parameters, such as tunes, Twiss parameters, dispersion function, at the commissioning stage in a high intensity proton machine. It gives a strong feedback for the RCS operation as a commissioning tool as well as for the studies of beam dynamics issues. Beam position monitors with finite resolutions, a transverse exciter to measure the betatron frequency, and a RF system with variable frequency to simulate off-momentum optics have been implemented into the system. The virtual accelerator system itself and some results of beam dynamics studies will be presented.  
 
WEPCH180 A Dramatically Reduced Size in the Gantry design for the Proton-Carbon Therapy hadron, focusing, dipole, quadrupole 2352
 
  • D. Trbojevic, R.C. Gupta, B. Parker
    BNL, Upton, Long Island, New York
  • E. Keil
    CERN, Geneva
  • A. Sessler
    LBNL, Berkeley, California
  Gantries in the proton/carbon cancer therapy machines represent the major cost and are usually very large. This report explains a new way for the gantry design. The size and cost of the gantries are reduced, and their use is simplified by using the fixed magnetic field. The "new" gantry is made of a very large momentum acceptance non-scaling Fixed Field Alternating Gradient (FFAG) quarter and half arc beam lines. The gantry is made of combined function magnets with a very strong focusing and small dispersion function. Additional magnets with a fast response are required to allow adjustments of the beam position for different energies at the beginning of the gantry. The strong focusing magnets following the gantry have to be adjustable as well to provide the required spot size. The adjustable dipoles provide the radial scanning. The fixed field combined function magnets could be made of small permanent magnets for the proton machine, or of the high temperature superconductors or superconductors for the carbon machine, reducing dramatically the size.  
 
WEPLS019 Parameters for Absorber-based Reverse Emittance Exchange of Muon Beams emittance, collider, acceleration, scattering 2433
 
  • R.P. Johnson
    Muons, Inc, Batavia
  • Y.S. Derbenev
    Jefferson Lab, Newport News, Virginia
  The normalized longitudinal emittance of a muon beam after six-dimensional ionization cooling appears very small compared to the value that could be utilized or maintained after acceleration to muon collider energy. This circumstance offers the possibility for further reduction of the transverse emittance by introducing absorber-based reverse emittance exchange (REMEX) between longitudinal and transverse degrees of freedom before acceleration to high energy. REMEX follows Parametric-resonance Ionization Cooling and is accomplished in two stages. In the first stage the beam is stretched to fill the RF bucket at the initial cooling energy. In the second stage the beam is accelerated to about 2.5 GeV, where energy straggling begins to limit the absorber technique, and stretched again. The potential transverse emittance reduction and the intrinsic limitations of the REMEX technique have been analyzed earlier. In this report, we describe the required beam transport and RF parameters needed to achieve the maximum REMEX effect.  
 
THPCH032 Instability Studies Using Evaluated Wake Fields and Comparison with Observations at SOLEIL impedance, SOLEIL, single-bunch, simulation 2847
 
  • R. Nagaoka
    SOLEIL, Gif-sur-Yvette
  Beam instability is predicted for SOLEIL using the impedance data obtained through component-wise numerical evaluations. The paper also attempts to make the first comparison with measurements. A key issue for SOLEIL has been to acquire precise knowledge of impedance up to a few tens of GHz, due to short bunches, of chambers which are essentially 3D and additionally NEG coated to a large part, which is expected to enhance the reactive part of the resistive-wall impedance. The predictability of instabilities with the data attained thus becomes a large concern. Wake potentials computed with a 3D code are transformed to impedances and decomposed into a series of resonators, inductive and resistive components, to deduce the wake functions, while for NEG coated chambers, they are numerically Fourier transformed from analytically derived impedances. Both time and frequency domain simulations are performed to predict the longitudinal and transverse instabilities in single bunch, as well as resistive-wall instabilities in multibunch as a function of chromaticity. A multibunch tracking is also performed to investigate the filling pattern dependence of the latter.  
 
THPCH048 Transverse Coupled Bunch Instability Driven by 792-MHz Cavity HOM in NewSUBARU Electron Storage Ring damping, emittance, synchrotron, pick-up 2892
 
  • S.H. Hisao, A. Ando, S. Hashimoto, T. Matsubara, Y. Miyahara, Y. Shoji
    NewSUBARU/SPring-8, Laboratory of Advanced Science and Technology for Industry (LASTI), Hyogo
  The 792-MHz HOM of the RF cavity can drive horizontal coupled bunch instability in the NewSUBARU electron storage ring. This instability is now avoided by tuning the HOM frequency with an additional tuner (HOM tuner). Detailed characteristics of this instability were investigated by changing the HOM frequency, betatron tune, chromaticity and magnitude of the stored current at the energy of 1 GeV. The experiments were performed with 6-bunch equi-space filling to clarify the mode number. Bunch oscillations show saw-tooth patterns when the stored current is not so large. The measured results are compared with an analytical calculation using a rigid bunch model and Sacherer's formalism. The fundamental aspects can be well explained by the calculation, but there exist many problems that cannot be explained by the rigid bunch model.  
 
THPCH050 Further Studies on Betatron Sidebands due to Electron Clouds electron, synchrotron, feedback, KEKB 2898
 
  • J.W. Flanagan, H. Fukuma, Y. Funakoshi, S. Hiramatsu, T. Ieiri, H. Ikeda, K. Ohmi, K. Oide, M. Tobiyama
    KEK, Ibaraki
  We have observed vertical betatron sidebands in the transverse beam spectra of positron bunches at the KEKB LER which are associated with the presence of electron clouds in single-beam studies*, and which are also associated with a loss of luminosity when the KEKB beams are in collision**. The sidebands may be signals of a fast head-tail instability due to short-range wakes within the electron cloud, providing a diagnostic for exploring the mechanism for transverse beam blow-up due to electron clouds. We report here on further studies on the behavior of the sidebands under varying beam conditions, including varying initial beam size below the beam blow-up threshold, chromaticity, RF voltage and fill pattern.

*J. W. Flanagan et al. PRL 94, 054801 (2005).**J. W. Flanagan et al. Proc. PAC05, p. 680 (2005).

 
 
THPCH052 Dependence of Transverse Instabilities on Amplitude Dependent Tune Shifts octupole, feedback, ion, factory 2904
 
  • T. Miyajima, K. Harada, Y. Kobayashi, S. Nagahashi
    KEK, Ibaraki
  In the Photon Factory electron storage ring, transverse instabilities have been observed in multi-bunch operation mode. The instabilities can be suppressed by amplitude dependent tune shifts, which are induced by the sextupole, octupole and higher order magnetic field. Since four octupole magnets have been installed in the PF ring, we can control the tune shifts, which is caused by the octupole magnetic field, independently of chromaticities, which is caused by sextupole magnetic field. In order to research the suppression mechanism of the instabilities, we measured the dependence of the instabilities on the tune shifts, which are induced by the octupole field. The threshold of the tune shifts, which suppress the instabilities, were observed in the measurement, and it depended on the filling pattern of the bunch train and the beam current per bunch. In addition, we will present the results of the measurement before and after the reconstruction for the straight-sections upgrade at the PF ring, which was carried out in 2005.  
 
THPCH077 Resistive-wall Instability in the Damping Rings of the ILC impedance, feedback, damping, vacuum 2964
 
  • L. Wang, K.L.F. Bane, T.O. Raubenheimer, M.C. Ross
    SLAC, Menlo Park, California
  In the damping rings of the International Linear Collider (ILC), the resistive-wall instability is one of the dominant transverse instabilities. This instability directly influences the choice of material and aperture of the vacuum pipe, and the parameters of the transverse feedback system. This paper investigates the resistive-wall instabilities in an ILC damping ring under various conditions of beam pipe material, aperture, and fill pattern.  
 
THPCH105 Summary of Coupling and Tune Feedback Results during RHIC Run 6, and Possible Implications for LHC Commissioning coupling, feedback, RHIC, LHC 3044
 
  • P. Cameron, A. Della Penna, L.T. Hoff, Y. Luo, A. Marusic, V. Ptitsyn, C. Schultheiss
    BNL, Upton, Long Island, New York
  • M. Gasior, O.R. Jones
    CERN, Geneva
  • C.-Y. Tan
    Fermilab, Batavia, Illinois
  Efforts to implement tune feedback during the acceleration ramp in RHIC have been hampered by the effect of large betatron coupling, as well as by the large dynamic range required by transition crossing with ion beams. Both problems have been addressed, the first by implementation of continuous measurement of coupling using the phase-locked tune meter, and the second by the development of the direct diode detection analog front end. Performance with these improvements will be evaluated during the first days of RHIC Run 6 beam commissioning. With positive results, the possibility of implementing operational feedback control of tune and coupling during beam commissioning will be considered. After beam commissioning, chromaticity feedback will be explored as a part of the accelerator physics experimental program. We will summarize the results of these investigations, and discuss possible implications of these results for LHC commissioning.  
 
THPLS058 MAX III Commissioning vacuum, injection, dipole, electron 3416
 
  • M. Eriksson, M. Bergqvist, M. Brandin, L.-J. Lindgren, M. Sjöström, S. Thorin
    MAX-lab, Lund
  Some of the features of the 700 MeV MAX III synchrotron radiation storage ring are presented, and the commissioning of this ring is described.  
 
THPLS067 Vertical Beam Size Control in TLS and TPS coupling, emittance, feedback, quadrupole 3442
 
  • C.-C. Kuo, H.-P. Chang, J.-R. Chen, P.J. Chou, K.-T. Hsu, G.-H. Luo, H.-J. Tsai, D.-J. Wang, M.-H. Wang
    NSRRC, Hsinchu
  • A. Chao
    SLAC, Menlo Park, California
  • W.-T. Weng
    BNL, Upton, Long Island, New York
  Vertical beam size control is an important issue in the light source operations. The horizontal-vertical betatron coupling and vertical dispersion were measured and corrected to small values in the TLS 1.5 GeV storage ring. Estimated beam sizes are compared with the measured values. By employing an effective transverse damping system, the vertical beam blow-up due to transverse coherent instabilities such as the fast-ion beam instability was suppressed and as a result, the light source is very stable. In NSRRC we are designing an ultra low emittance 3-GeV storage ring and its designed vertical beam size could be as small as a few microns. The ground and mechanic vibration effects, and coherent instabilities could spoil the expected photon brightness due to blow-up of the vertical beam size if not well taken care of. The contributions of these effects to vertical beam size increase will be evaluated and the counter measures to minimize them will be proposed and reported in this paper.  
 
THPLS078 Tests of a New Bunch Cleaning Technique for the Advanced Light Source injection, storage-ring, kicker, controls 3463
 
  • F. Sannibale, W. Barry, M.J. Chin
    LBNL, Berkeley, California
  A new bunch cleaning technique is being tested at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory. The new procedure allows for high purity, arbitrary filling patterns and is potentially compatible with standard user operation and with the incoming top-off injection mode. The description of the new system and the results of the first tests at the ALS are presented.