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closed-orbit

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MOPLS053 Beta-beat Correction Using Strong Sextupole Bumps in PEP-II sextupole, luminosity, coupling, SLAC 664
 
  • G. Yocky
    SLAC, Menlo Park, California
  A method for correcting lattice beta mismatches has been developed for the PEP-II collider using orbit offsets in strong sextupoles. The solution is first predicted in the MAD program by modeling closed orbit bumps in the plane of correction at the sextupoles strongest in that plane. The derived solution is then tested in the machine to confirm the prediction and finally dialed into the machine under high-current conditions.  
 
TUPCH056 A Simpler Method for SR Interferometer Calibration extraction, KEKB, luminosity, synchrotron 1136
 
  • J.W. Flanagan, H. Fukuma, S. Hiramatsu, H. Ikeda, T. Mitsuhashi
    KEK, Ibaraki
  Previous methods of performing absolute calibration of the SR interferometer used at KEKB (measuring mirror distortion with a pinhole mask, virtual beam broadening via local bumps, physical beam broadening via dispersion bumps) are very time-consuming, and require dedicated machine time to take the necessary data. We report on a new, simpler method we have developed, wherein we create small local bumps at the SR source point and observe the resulting shifts in the phase of the interference fringes. From these data we can calibrate the total magnification of the system, including the effects of mirror distortion. The calibration data can be taken in a very small amount of time (tens of minutes), and in parallel with physics running, without stopping the beam-size measurement system or interfering with its use for luminosity tuning. By taking the calibration data at different beam currents and correlating the magnification at each current with the appropriate interference pattern fit parameters, we can also obtain the parameters needed for real-time mirror distortion correction.  
 
TUPCH063 Novel Method for Beam Dynamics using an Alpha Particle Source simulation, injection, betatron, 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.  
 
TUPLS054 The Isochronous Mode of the Collector Ring emittance, ion, quadrupole, octupole 1618
 
  • S.A. Litvinov, A. Dolinskii, H. Geissel, F. Nolden, M. Steck, H. Weick
    GSI, Darmstadt
  The isochronous mode of a storage ring is a special ion-optical setting in which the revolution time of circulating ions of one species does not depend on their velocity spread. In this mode the ring can be used for mass measurement of exotic nuclei. The Collector Ring (CR) [1] of the FAIR project [2] will operate in such mode as time-of-flight spectrometer for short-lived exotic nuclei (T1/2 > 20 μs) produced and selected in flight with the Super-FRS fragment separator [3]. This technique has been developed at the ESR [4]. The dependence of the revolution time in the isochronous ring from its transverse acceptance, the closed orbit distortion, and nonlinear imperfection of the magnet field was investigated analytically and with a Monte-Carlo simulation. The corresponding results will be presented.

References: [1] A. Dolinskii et. al., GSI Annual Report, 2004 [2] W. Henning, Nucl. Phys. A721 (2003)211c [3] H. Geissel, et. al., Nucl. Instr. Meth. B204 (2003)71 [4] M. Hausmann et. al., Nucl. Instr. Meth. A 446 (2000)569

 
 
TUPLS071 Minimum Cost Lattices for Nonscaling FFAGs lattice, LEFT, acceleration, quadrupole 1660
 
  • S.R. Koscielniak
    TRIUMF, Vancouver
  Previously, linear-field FFAG lattices for muon acceleration have been optimized under the condition of minimum path length variation. For non-relativistic particles, as are employed in the hadron therapy of cancer, that constraint is removed allowing a wider range of design choices. We adopt the thin-element kick model for a degenerate F0D0 cell composed of D and F combined function magnets. The dipole field components are parametrised in terms of the bending at the reference momentum and the reverse bend angle. The split between positive and negative bending sets the shape of the closed orbits. The cost function, based on stored magnetic energy, is explored in terms of the split. Two cost minima are found, one corresponding to minimum peak magnet field in the F element, and another to minimum radial aperture in the D element. Analytic formulae are given for the minimization conditions. The minimum field lattice is similar to existing designs based on minimizing the path length variation, but the minimum aperture lattice presents a new direction for future detailed design studies.  
 
TUPLS072 Nonscaling FFAG with Equal Longitudinal and Transverse Reference Momenta lattice, radio-frequency, acceleration, controls 1663
 
  • S.R. Koscielniak
    TRIUMF, Vancouver
  An unusual feature of linear-field nonscaling FFAG designs is that the radio-frequency is not necessarily synchronous with the reference orbit and momentum chosen for the lattice design. This arises because optics design prefers the reference geometry to be composed of straight lines and arcs of circles - either at the mean momentum, or at high momentum to centre the orbit in the F element. The asynchronous acceleration proposed for rapid acceleration has strong requirements to set the longitudinal reference at 1/4 and 3/4 of the momentum range to minimize phase slip. The usual particle-tracking programs, such as MAD, though sophisticated in the transverse plane, are far cruder in their longitudinal working and do not allow for a longitudinal reference momentum and RF phase independent of the transverse values. In the context of a thin-element lattice model, we show how to make the transverse reference momentum and optic design coincident with the longitudinal reference by adjusting the ratio of positive and negative bending in the D and F elements, respectively, and retaining a lines and arcs composition for the reference orbit. This prepares the way for MAD tracking.  
 
WEPCH016 Spurious Vertical Dispersion Correction for PETRA III quadrupole, emittance, wiggler, damping 1954
 
  • G.K. Sahoo, K. Balewski, W. Decking
    DESY, Hamburg
  Spurious vertical dispersion, arising due to the misalignment and rotational errors of magnets in synchrotron radiation sources with low emittances, are highly undesirable as this contributes to the vertical beam size of the photon beam. This is a matter of concern in PETRA III, a 6GeV light source with a designed horizontal emittance of 1nm.rad and 1% emittance coupling. It has a hybrid lattice of FODO and DBA cells, which will be installed in one-eighth of the existing PETRA II ring. In this paper local and global vertical dispersion corrections are discussed. The global vertical dispersion is corrected using vertical corrector magnets (may also consider 12 skew quadrupole magnets), and the skew quadrupoles are used for local correction as well. Eight of them are placed close to the two damping wiggler sections used for minimizing the horizontal emittance. The remaining four are placed in the new octant with DBA cells where insertion devices are installed.  
 
WEPCH023 Longitudinal Coherent Oscillation Induced in Quasi-isochronous Ring synchrotron, power-supply, electron, storage-ring 1972
 
  • Y. Shoji, Y. Hisaoka, T. Matsubara, T. Mitsui
    NewSUBARU/SPring-8, Laboratory of Advanced Science and Technology for Industry (LASTI), Hyogo
  Noise sources, which excite longitudinal coherent oscillation is discussed. Especially in a quasi-isochronous electron storage ring an identification of the noise sources is important to obtain an extremely short bunch. One possible source is a well-known rf noise in the acceleration field. The other is a magnetic field ripple, which changes a path-length for a revolution. The analytical formula for the longitudinal coherent oscillation is explained. It contains the path-length oscillation, which had never been considered. The third is a beam itself, probably be a coherent radiation loss. The driving term is not symmetric along the energy axis, then the oscillation amplitude depends on the higher order momentum compaction factor.  
 
WEPCH026 Recent Progress of Optics Measurement and Correction at KEKB optics, sextupole, KEKB, betatron 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.  
 
WEPCH032 Orbit Correction System for S-LSR Dispersion-free Mode proton, kicker, electron, ion 1993
 
  • H. Souda, S. Fujimoto, M. Ikegami, A. Noda, T. Shirai, M. Tanabe
    Kyoto ICR, Uji, Kyoto
  • H. Fadil
    MPI-K, Heidelberg
  An ion storage ring S-LSR has been constructed at ICR, Kyoto Univ. It is a small ring with 22.557m circumference, and has an electron cooler and laser cooling section to achieve crystalline beam. In the commissioning process, closed orbit correction of a 7MeV proton beam has been successfully realized by means of Simplex Method. Responses to the correctors are linear only within narrow limits because of the space-charge effect in the electron cooler. Therefore, the correction must be repetition of small corrections. Under such condition, measured COD has been reduced less than 0.1mm. Orbit correction is necessary for 35keV Mg+ dispersion-free mode* using both bending magnets and electrostatic deflectors. Since electrostatic deflectors have relatively large field errors, it needs a special process to inject the beam into the dispersion-free mode ring. First circulation is under only the magnetic field, then, the electric field will be added little by little applying continuous COD correction. In this way the dispersion gradually diminishes with keeping stable orbit. In this paper we present the correction scheme and the trial to the dispersion-free circulation.

*M. Ikegami et al. Phys. Rev. ST-AB, 7, 120101-1 (2004).

 
 
WEPCH049 Closed Orbit Correction of TPS Storage Ring dipole, quadrupole, synchrotron, emittance 2029
 
  • H.-J. Tsai, H.-P. Chang, P.J. Chou, C.-C. Kuo, G.-H. Luo, M.-H. Wang
    NSRRC, Hsinchu
  A 3 GeV synchrotron storage ring is proposed in Taiwan to serve the synchrotron light users, especially for the x-ray community. The ring consists of 24 double-bend cells with 6-fold symmetry and the circumference is 518.4 m. The designed natural emittance with slightly positive dispersion in the straight sections is less than 2 nm-rad. This low emittance lattice structure needs strong quadrupoles and sextupoles and the closed orbit distortions are sensitive to the alignment errors in the quadrupoles and sextupoles as well. The closed orbit distortions due to tolerable magnetic errors are simulated and the correction scheme is proposed. Using singular value decomposition method, the closed orbit distortions are corrected and corrector strengths as well as the residual closed orbit distortions are obtained.  
 
WEPCH145 Particle Tracking and Simulation on the .NET Framework simulation, lattice, KEK, controls 2263
 
  • H. Nishimura, T. Scarvie
    LBNL, Berkeley, California
  Particle tracking and simulation studies are becoming complex. In addition to the sophisticated graphics, interactive scripting is becoming popular. A compatibility with the control system requires network and database capabilities. It is not a trivial task to fulfill various requirements without sacrificing the runtime performance. We evaluate the use of .NET to solve this issue by converting a C++ code Goemon* that is an object-oriented version of Tracy developed at ALS. The portability to other platforms will be mentioned in terms of Mono.

*H. Nishimura, PAC'01, Chicago, July 2001, p.3066.

 
 
THPCH091 Status of the ELETTRA Global Orbit Feedback Project feedback, controls, electron, ELETTRA 3003
 
  • M. Lonza, D. Bulfone, R. De Monte, V. Forchi', G. Gaio
    ELETTRA, Basovizza, Trieste
  A fast digital feedback system is under development to stabilize the electron beam closed orbit at the ELETTRA storage ring in the band up to 300 Hz. In view of the implementation of the feedback, the existing orbit measurement system will be upgraded to allow for better accuracy in the beam position measurement and higher acquisition rate. A global correction algorithm running on a number of distributed processing units will correct the orbit using all of the storage ring steerer magnets. The status of the project development is given in this article.  
 
THPCH100 New Fast Dither System for PEP-II feedback, luminosity, controls, SLAC 3029
 
  • S.M. Gierman, S. Ecklund, R.C. Field, A.S. Fisher, P. Grossberg, K.E. Krauter, E.S. Miller, M. Petree, K.G. Sonnad, N. Spencer, M.K. Sullivan, K.K. Underwood, U. Wienands
    SLAC, Menlo Park, California
  The PEP-II B-Factory uses multiple feedback systems to stabilize the orbits of its stored beams and to optimize their performance in collision [1]. This paper describes an upgrade to the feedback system responsible for optimizing the overlap of colliding beams at the interaction point (IP). The effort was motivated by a desire to shorten the response time of the feedback, particularly in the context of machine-tuning tasks. We describe the original feedback system, the design for the new one, and give a status report on the installation.  
 
THPLS009 First Results of the Commissioning of SOLEIL Storage Rings storage-ring, SOLEIL, injection, quadrupole 3284
 
  • A. Nadji, J.C. Besson, P. Betinelli, P. Brunelle, A. Buteau, L. Cassinari, M.-E. Couprie, J.-C. Denard, J.-M. Filhol, P. Gros, C. Herbeaux, J.-F. Lamarre, P. Lebasque, M.-P. Level, A. Loulergue, A. Madur, P. Marchand, L.S. Nadolski, R. Nagaoka, B. Pottin, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  The commissioning of SOLEIL's storage ring will start in April 2006. The objective is to reach, within a first phase of two months, stable beam conditions at 100 mA in the multi-bunch mode that can be used for the commissioning of the beamlines. This is a challenging objective, especially because the SOLEIL's ring is incorporating some innovative techniques such as the use of a superconducting RF cavity, NEG coating for all straight parts of the machine and new BPM electronics. Prior to the start of the commissioning, some insertion devices and most of the insertion devices low gap vacuum vessels, including 10 mm inner vertical aperture vessels for the Apple-II type, will be installed on the ring. This paper will review the performances of all these equipment in presence of the beam. The results of the first commissioning runs will be presented.