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Paper Title Other Keywords Page
MOPC001 Final Results from the Novel Multiturn Extraction Studies at CERN Proton Synchrotron extraction, resonance, proton, septum 117
  • M. Giovannozzi, R. Cappi, S.S. Gilardoni, M. Martini, E. Métral, R.R. Steerenberg
    CERN, Geneva
  • A.-S. Müller
    FZK, Karlsruhe
  Recently a novel approach to perform multi-turn extraction was proposed based on beam splitting in the transverse phase space by means of trapping inside stable islands. An experimental campaign was launched since the year 2002 to assess the feasibility of such an extraction scheme at the CERN Proton Synchrotron. During the year 2004 run, a high-intensity single-bunch beam was successfully split and the generated beamlets separated without any measurable losses. The latest experimental results are presented and discussed in details in this paper. These achievements represent a substantial step forward with respect to what achieved in previous years, as only a low-intensity bunch could be split without losses. Furthermore, this opens the possibility of using such a technique for routine operation with the high-intensity proton beams required for the planned CERN Neutrino to Gran Sasso Project.  
MPPE006 Particle Distribution Function Forming in Nonlinear Systems quadrupole, focusing, target, lattice 985
  • S.N. Andrianov, S. Edamenko
    St. Petersburg State University, Applied Mathematics & Control Processes Faculty, St. Petersburg
  Modern ion-optical systems are used in different fields of beam physics both independent facilities as consisting of largemachines. One of these destination is to create beams with a desired distribution of beams particles. Often there is a need to ensure a homogeneous distribution for a terminal beam phase portrait in a transverse configuration space. This is one of problems of nonlinear aberrations management. It is known that nonlinearity properties inhere to any beam lines. Such these nonlinearities have unremovable character, and their influence can be remove using only special nonlinear lattice elements, which are introduced artificially into the beam line. In this paper we suggest a procedure to find necessary nonlinear correcting control elements for purposive forming of beam particle distribution functions.  
MPPE008 Synthesis of Beam Lines with Necessary Properties quadrupole, focusing, target, simulation 1096
  • S.N. Andrianov
    St. Petersburg State University, Applied Mathematics & Control Processes Faculty, St. Petersburg
  In this paper a new approach to the problem of synthesis of beam lines is discussed. Usually this problem can be overcome by the use of numerical simulation and optimal control theory methods. But this results in sufficiently great number of variable parameters and functions. Obviously, that this degrades quality of a modeling procedure. The suggested approach is demonstrated on a problem of a microprobe design problem. Essence of the problem is that necessary to design a high precision focusing system which satisfies some additional conditions. For solution of this problem we use an algebraic treatment based on Lie algebraic methods and computer algebra techniques. Using the symmetry ideology this approach allows rewriting beam properties to enough simple conditions for control parameters and functions. This leads a set of desired solutions and show results in some most suitable form. Moreover, this approach decreases the number of variable parameters.  
MPPE021 Non-Linear Beam Transport System for the LENS 7 MeV Proton Beam target, proton, beam-transport, quadrupole 1704
  • W.P. Jones, D.V. Baxter, V.P. Derenchuk, T. Rinckel, K. A. Solberg
    IUCF, Bloomington, Indiana
  Funding: This work has been supported by the National Science Foundation under grants DMR-0220560 and DMR–0320627, by the Indiana 21st Century Science and Technology Fund, and by the Department of Defense.

A beam transport system has been designed to carry a high-intensity low-emittance proton beam from the exit of the RFQ-DTL acceleration system of the Indiana University Low Energy Neutron System (LENS)* to the neutron production target. The goal of the design was to provide a beam of uniform density over a 3cm by 3cm area at the target. Two octupole magnets** are employed in the beam line to provide the necessary beam phase space manipulations to achieve this goal. First order calculations were done using TRANSPORT and second order calculations have been performed using TURTLE. Second order simulations have been done using both a Gaussian beam distribution and a particle set generated by calculations of beam transport through the RFQ-DTL using PARMILA. Comparison of the design characteristics with initial measurements from the LENS commissioning process will be made.

*V.P. Derenchuk et al., "The LENS 7 MeV, 10mA proton Linac," these proceedings. **E. Kashy & B. Sherrill, Nuclear Instruments and Methods in Physics Research, B26 (1987) p. 610.

MPPE030 Comparison of Off-Line IR Bump and Action-Angle Kick Minimization sextupole, simulation, resonance, interaction-region 2116
  • Y. Luo, F.C. Pilat, V. Ptitsyn, D. Trbojevic, J. Wei
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886.

The interaction region bump (IR bump) nonlinear correction method has been used for the sextupole and octupole field error on-line corrections in the Relativistic Heavy Ion Collider (RHIC). Some differences were found for the sextupole and octupole corrector strengths between the on-line IR bump correction and the predictions from the action-angle kick minimization. In this report we compare the corrector strengths from these two methods based on the RHIC Blue ring lattice with the IR nonlinear modeling. The comparison confirms the differences between resulting corrector strengths. And the reason for the differences is found and discussed. It is followed by a further discussion of the operational IR bump applications to the octupole, and skew sextupole and skew quadrupole field error corrections.

MPPE061 Measurement and Correction of Nonlinear Chromaticity in RHIC insertion, optics, luminosity, sextupole 3523
  • S. Tepikian, P. Cameron, A. Della Penna, V. Ptitsyn
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy.

To improve luminosity in RHIC by using smaller Beta,* higher order chromatic effects may need to be corrected. Measuring of higher order chromaticities is discussed and compared to a model of RHIC, showing good agreement. Assuming round beams, four families of octupoles are used to correct the second order chromaticities while keeping under control the amplitude dependent betatron tune spread in the beams. We show that the octupoles can reduce the second order chromaticity in RHIC, but they have insufficient strength for complete correction.

MPPP042 Landau Damping of the Weak Head-Tail Instability at Tevatron damping, betatron, proton, injection 2714
  • P.M. Ivanov, Y. Alexahin, J. Annala, V. Lebedev, V.D. Shiltsev
    Fermilab, Batavia, Illinois
  Landau damping of the head-tail modes in Tevatron beam with the help of octupole-generated betatron tune spreads permits to reduce chromaticity from 15-20 units to zero thus significantly improving the beam lifetime. The octupole strengths have been experimentally optimized at different stages of the Tevatron operation, from proton injection to collision. Predictions of the analytical Landau damping model are compared with the experimental results.  
MPPP043 Betatron Tune Spread Generation and Differential Chromaticity Control by Octupole at Tevatron betatron, proton, antiproton, injection 2756
  • P.M. Ivanov, Y. Alexahin, J. Annala, V. Lebedev
    Fermilab, Batavia, Illinois
  Application of octupoles for Landau damping of the unstable head-tail modes requires careful consideration at their combination into separate families to insure maximum effectiveness and avoid degradation of the dynamic aperture due to the non-linear magnetic fields. Existing octupolar magnets around the machine have been arranged into four functional families with individual power supplies. Two of these families generate betatron tune spreads in the vertical and horizontal planes whereas the other two control the differential chromaticity between the proton and antiproton helices. The calculated effect on tunes and chromaticity is compared with direct measurements. Analytical formulas for betatron tune spectral density functions are presented.  
MPPT050 Test Results for LHC Insertion Region Dipole Magnets dipole, quadrupole, sextupole, insertion 3106
  • J.F. Muratore, M. Anerella, J.P. Cozzolino, G. Ganetis, A. Ghosh, R.C. Gupta, M. Harrison, A.K. Jain, A. Marone, S.R. Plate, J. Schmalzle, R.A. Thomas, P. Wanderer, E. Willen, K.-C. Wu
    BNL, Upton, Long Island, New York
  Funding: U.S. Department of Energy.

The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) has made 20 insertion region dipoles for the Large Hadron Collider (LHC) at CERN. These 9.45 m-long, 8 cm aperture magnets have the same coil design as the arc dipoles now operating in the Relativistic Heavy Ion Collider (RHIC) at BNL and are of single aperture, twin aperture, and double cold mass configurations. They produce fields up to 3.8 T for operation at 7.56 TeV. Eighteen of these magnets have been tested at 4.5 K using either forced flow supercritical helium or liquid helium. The testing was especially important for the twin aperture models, which have the most challenging design. In these, the dipole fields in both apertures point in the same direction, unlike LHC arc dipoles. This paper reports on the results of these tests, including spontaneous quench performance, verification of quench protection heater operation, and magnetic field quality. Magnetic field measurements were done at 4.5K and at room temperature, and warm-cold correlations have been determined. Some dynamic measurements to study the effect of time decay and snapback at injection were also done, using a fast rotating coil.

MPPT064 Elements of Magneto-Optics Acting in One Direction wiggler, focusing, multipole, quadrupole 3618
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  We describe here the way to use quadrupole, octupole lenses so they are acting in one direction only. The beam is running across the lens in contrast with usual axis running.  
TOAC001 Overview of Impedance and Single-Beam Instability Mechanisms impedance, coupling, synchrotron, damping 14
  • E. Métral
    CERN, Geneva
  Single-bunch and coupled-bunch instability mechanisms will be reviewed in both longitudinal and transverse planes. The resistive-wall impedance will be discussed in the particular case of the LHC collimators, which reveal a new physical regime. Stabilization by Landau damping, feedbacks, or linear coupling between the transverse planes will also be treated. Benchmarking of analytical predictions with some instability codes will be shown as well as several experimental results.  
TOAA010 Serpentine Coil Topology for BNL Direct Wind Superconducting Magnets quadrupole, dipole, superconducting-magnet, multipole 737
  • B. Parker, J. Escallier
    BNL, Upton, Long Island, New York
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC-02-98-CH10886.

BNL direct wind technology, with the conductor pattern laid out without need for extra tooling (no collars, coil presses etc.) began with RHIC corrector production. RHIC patterns were wound flat and then wrapped on cylindrical support tubes. Later for the HERA-II IR magnets we improved conductor placement precision by winding directly on a support tube. To meet HERA-II space and field quality goals took sophisticated coil patterns, (some wound on tapered tubes). We denote such patterns, topologically equivalent to RHIC flat windings, "planar patterns." Multi-layer planar patterns run into trouble because it is hard to wind across existing turns and magnet leads get trapped at poles. So we invented a new "Serpentine" winding style, which goes around 360 degrees while the conductor winds back and forth on the tube. To avoid making solenoidal fields, we wind Serpentine layers in opposite handed pairs. With a Serpentine pattern each turn can have the same projection on the coil axis and integral field harmonics then closely follow the 2D cross section. This and other special Serpentine coils properties are discussed in this paper and applied to a variety of direct wind magnet projects.

TPAP029 Measurements of Field Decay and Snapback Effect on Tevatron Dipole and Quadrupole Magnets injection, sextupole, quadrupole, dipole 2098
  • G. Velev, G. Ambrosio, G. Annala, P. Bauer, R. H. Carcagno, J. DiMarco, H.D. Glass, R. Hanft, R.D. Kephart, M.J. Lamm, M.A. Martens, P. Schlabach, C. Sylvester, M. Tartaglia, J. Tompkins
    Fermilab, Batavia, Illinois
  Since the beginning of 2002 an intensive measurement program has been performed at the Fermilab Magnet Test Facility to understand dynamic effects in the Tevatron magnets. Based on the results of this program a new correction algorithm was proposed to compensate for the decay of the sextupole field during the dwell at injection and for the subsequent field "snapback" during the first few seconds of the energy ramp. Beam studies showed that the new correction algorithm works better than the original one, and improves the Tevatron efficiency by at least 3%. The beam studies also indicated insufficient correction during the first 20 s of the injection plateau where an unexpected discrepancy of 0.15 sextupole units of extra drift was observed. This paper reports on the most recent measurements of the Tevatron dipoles field at the beginning of the injection plateau. Results on the field decay and snapback in the Tevatron quadrupoles are also presented.  
TPAT027 Measurement of Transverse Echoes in RHIC quadrupole, dipole, lattice, scattering 1955
  • W. Fischer, T. Satogata
    BNL, Upton, Long Island, New York
  • R. Tomas
    CELLS, Bellaterra (Cerdanyola del Vallès)
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886.

Beam echoes are a very sensitive method to measure diffusion, and longitudinal echo measurements were performed in a number of machines. In RHIC, for the first time, a transverse beam echo was observed after applying a dipole kick followed by a quadrupole kick. After application of the dipole kick, the dipole moment decohered completely due to lattice nonlinearities. When a quadrupole kick is applied at time T after the dipole kick, the beam re-cohered at time 2T thus showing an echo response. We describe the experimental setup and measurement results. In the measurements the dipole and quadrupole kick amplitudes, amplitude dependent tune shift, and the time between dipole and quadrupole kick were varied. In addition, measurements were taken with gold bunches of different intensities. These should exhibit different transverse diffusion rates due to intra-beam scattering.

TPAT081 Observation of Electron-Ion Effects at RHIC Transition beam-losses, electron, emittance, vacuum 4087
  • J. Wei, M. Bai, M. Blaskiewicz, P. Cameron, R. Connolly, A. Della Penna, W. Fischer, H. Huang, U. Iriso, R.C. Lee, R.J. Michnoff, V. Ptitsyn, T. Roser, T. Satogata, S. Tepikian, L. Wang, S.Y. Zhang
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

Electron cloud is found to be a serious obstacle on the upgrade path of the Relativistic Heavy Ion Collider (RHIC). At twice the design number of bunches, electron-ion interactions cause significant instability, emittance growth, and beam loss along with vacuum pressure rises when the beam is accelerated across the transition.

WOAC007 Beam-Based Nonlinear Optics Corrections in Colliders sextupole, coupling, multipole, resonance 601
  • F.C. Pilat, Y. Luo, N. Malitsky, V. Ptitsyn
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the US Department of Energy

A method has been developed to measure and correct operationally the non-linear effects of the final focusing magnets in colliders, which gives access to the effects of multi-pole errors by applying closed orbit bumps, and analyzing the resulting tune and orbit shifts. This technique has been tested and used during 3 years of RHIC (the Relativistic Heavy Ion Collider at BNL) operations. I will discuss here the theoretical basis of the method, the experimental set-up, the correction results, the present understanding of the machine model, the potential and limitations of the method itself as compared with other non linear correction techniques.

RPAE002 Coupling Correction of a Circularly Polarizing Undulator at the Advanced Photon Source quadrupole, coupling, simulation, undulator 805
  • L. Emery
    ANL, Argonne, Illinois
  Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The electromagnetic Circularly Polarizing Undulator (CPU) installed at the Advanced Photon Source (APS) storage ring produces skew quadrupole field errors, which were initially corrected by a small skew quadrupole magnet at one end of the device. Because the storage ring is operated at 1% coupling or less, a correction not located at the source inside the CPU is insufficient, as we have confirmed in simulation. Adding a skew coil at the other end of the CPU allows us to make a complete correction of the coupling source in the undulator. Correction setpoints are determined by APS's general optimizing software with the vertical beam size of a x-ray pinhole image as a readback.

RPAE076 The Commission of Hefei Light Source After Reconstruction injection, closed-orbit, radiation, electron 3967
  • H. Xu, H. He, W. Li, G. Liu, L. Liu, S. Shang, B. Sun, L. Wang
    USTC/NSRL, Hefei, Anhui
  After the new four-kicker injection bump system was mounted, it was found that the magnetic field of four–kicker magnet through the same pulse current is different each other, the reason is which the width of pulse magnet fields is not same, so the four-kickers can not form completely local bump, and produce large global orbit distortion,and lead to beam loss. At last we found that the films of ceramic chambers were not plated evenly. The new rf system have two low level control circle circuits, which are the frequency and amplitude automatic adjustment systems. Because the energy of injection electron beam is 200MeV, and radiation damping is weak, so the gain of amplitude circuit was adjusted to the small value not to disturb beam.The beam load is large,and Robinson instability happen easily, so the small detune angle is preset. The Octupoles were inserted in ring for damping instability, and over compensated chromaticity was adjusted.Superconductor wiggler bring the variation of beta function, and the beam life time decreased from 8 hours to about 3 hours. By adjusting the beta functions close to situation ago, the beam lifetime was improved.  
RPAT098 Phase-Space Dynamic Tracking by a Two Pickups Data Acquisition System sextupole, lattice, pick-up, kicker 4326
  • A. Drago, M.E. Biagini, S. Guiducci, C. Milardi, M.A. Preger, C. Vaccarezza, M. Zobov
    INFN/LNF, Frascati (Roma)
  A two pickups dynamic tracking data acquisition system has been developed at LNF for the DAFNE Phi-factory. Two oscilloscopes sample horizontal and vertical sum and difference signals from two pickups simultaneously; the sampling clock is locked to the DAFNE timing system. A horizontal kick excites the beam motion and initiates the acquisition. Turn-by-turn signals are converted to beam position and stored on a server in a database using timestamp labels. Oscillation amplitude versus time, phase space distribution and frequency domain analysis are shown for several lattices and different settings of sextupoles and octupoles. Results are used to check the DAFNE non-linear model.  
RPPE074 The Multichannel Deflection Plates Control System for the ALF Facility at the APS ion, power-supply, controls, free-electron-laser 3937
  • B. Deriy
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

A deflection plate control system was developed as part of SPIRIT (Single Photon Ionization / Resonant Ionization to Threshold), a new secondary neutral mass spectrometry (SNMS) instrument that uses tunable vacuum ultraviolet light from the ALF (Argonne Linear Free-electron laser) facility at the APS for postionization. The system comprises a crate controller with PC104 embedded computer, 32 amplifiers, and two 1-kV power supplies. Thirty-two D/A converters are used to control voltages at the deflection plates within ± 400 V with 100-mV resolution. An algorithm of simultaneous sweeping of up to 16 XY areas with 10-μs time resolution also has been implemented in the embedded computer. The purpose of the system is to supply potentials to various ion optical elements for electrostatic control of keV primary and secondary ion beams in this SNMS instrument. The control system is of particular value in supplying (1) bipolar potentials for steering ions, (2) multiple potentials for octupole lenses that shape the ion beams, and (3) ramped deflection potentials for rastering the primary ion beam. The system has been in use as part of the SPIRIT instrument at the ALF facility since 2002.