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Paper Title Other Keywords Page
MOPA001 Advances in the Understanding and Operations of Superconducting Colliders sextupole, injection, coupling, multipole 54
  • P. Bauer, G. Annala, M.A. Martens, V.D. Shiltsev, G. Velev
    Fermilab, Batavia, Illinois
  • L. Bottura, N.J. Sammut
    CERN, Geneva
  Chromaticity drift is a well-known and more or less understood phenomenon in superconducting colliders such as the Tevatron. Less known is the effect of tune and coupling drift, also observed in the Tevatron during injection. Recently, in the context of the Tevatron collider run II, extensive studies of chromaticity, tune and coupling drifts were conducted to improve Tevatron performance. The studies included not only beam studies but also extensive off-line magnetic measurements on spare Tevatron dipoles. Some of these measurements were conducted in collaboration with Cern. Cern’s interest in multipole drifts is related to the future LHC, which will have similar issues. The following will report on the results of these studies. A new result, which will be presented here also, is related to fast drifts occurring in the first few seconds of the injection porch. These fast drifts were observed first in the Tevatron and efforts are underway to explain them. The author will also attempt to broaden the discussion to include the discussion of drift effects in the accelerating fields of superconducting linear accelerators.  
MOPA003 Testing of the LHC Magnets in Cryogenic Conditions: Operation Challenges, Status, and Outlook cryogenics, quadrupole, superconducting-magnet, collider 250
  • V. Chohan
    CERN, Geneva
  For the Large Hadron Collider under construction at CERN and the testing of its 1706 lattice magnets in cryogenic conditions, considerable challenges had to be overcome since 2002 to arrive at the situation of today, with semi-routine operation of the purpose built tests facility. With the setting up of an Operation Team comprising of non-expert CERN Accelerator operation staff, few in number and a large external collaboration, it was essential to develop the methodology of working in light of external collaboration limits and base it on CERN-known techniques and experience in accelerator running-in, commissioning and routine operation. A flavour of the operation tools that were necessary or developed will be given, i.e., web-based tests follow-up management & information systems, development of precisely defined ‘to do list’ of tests sequences, associated methods, procedures and strict check-lists, electronic logbooks and so forth. The presentation will briefly outline the test programme and its context & constraints, give a summary of the accomplishments so far, together with the outlook for the successful completion of the whole programme within the project goals.  
MOPA005 Protection Against Accidental Beam Losses at the LHC beam-losses, proton, monitoring, superconducting-magnet 492
  • J. Wenninger, R. Schmidt
    CERN, Geneva
  Protection of the LHC against uncontrolled beam losses is of prime importance due to the very high stored beam energy. For nominal beam intensities, each of the two 7 TeV/c proton beams has a stored energy of 350 MJ threatening to damage accelerator equipment. At injection a number of passive beam absorbers must be correctly positioned and specific procedures have been proposed to ensure safe injection of high intensity. The LHC beam dump block being the only LHC element that can safety absorb the full LHC beam, it is essential that the beams are extracted unto the dump block in case of emergency. The failure time constants extend from 100 microseconds to few seconds depending on the equipment. Failures must be detected at a sufficiently early stage and transmitted to the beam interlock system that triggers the beam dumping system. To ensure safe operation the machine protection system uses a variety of systems to detect such failures. The strategy for protection of the LHC will be illustrated, with emphasis on new developments and studies that aim for an increased redundancy of the protection system.  
MOPA008 On the Feasibility of a Tripler Upgrade for LHC photon, synchrotron, injection, multipole 634
  • P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, Texas
  Funding: This work is supported by the U.S. Dept. of Energy, grant #DE-FG03-95ER40924.

Recent developments in the performance of superconductors and the design of high-field superconducting dipoles have opened the possibility to extend dipole field strength to ~25 Tesla in the arc dipoles of a future hadron collider. Design issues are presented for a concept of a Tripler upgrade of LHC, in which a second dual ring would be installed over the LHC ring in the same tunnel. Proton beams from LHC would be transferred to the Tripler midway through the LHC cycle and accelerated to ~20 TeV/beam for collisions. A number of obvious issues are explored. Synchrotron radiation power would be 80 times greater, but the critical energy would come as soft X-rays rather than hard UV, and so could be absorbed locally on ~150 K photon stops following each dipole so that total refrigeration power could perhaps be no more than that for LHC. Synchrotron damping would be dramatically enhanced in the Tripler compared to LHC, with damping times of ~one hour. Alternatives for beam transfer and low-beta insertions will be discussed. Like LHC, the Tripler would access new mass scales primarily through gluon fusion. The Tripler should reach about twice the mass scale attainable with LHC.

MOPA010 Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron injection, coupling, sextupole, collider 725
  • M.A. Martens, J. Annala, P. Bauer, V.D. Shiltsev, G. Velev
    Fermilab, Batavia, Illinois
  Chromaticity drift is a well-known and more or less well-understood phenomenon in superconducting colliders such as the Tevatron. Less known is the effect of tune and coupling drift, also observed in the Tevatron during injection. These effects are caused by field drifts in the superconducting magnets. Understanding of the behavior of the tune, coupling, and chromaticity at the start of the ramp is an important part of understanding the observed 5-10% loss in beam intensity at the start of the Tevatron ramp. In addition modifications in the Tevatron shot set-up procedure are being implemented to allow for a gain in integrated luminosity. In this context we conducted several beam-studies, during the period of April to August 2004, in which we measured the drift in the Tevatron chromaticity, tune and coupling during the injection porch. In some case we also measured the snapback at the start of the ramp. We will present the results of these studies data and put them into context of the results of off-line magnetic measurements conducted in spare Tevatron dipoles at the same time. Finally we will propose optimized feed-forward algorithms that successfully compensate for the drift effects in the Tevatron.  
MOPC007 Anisotropy-Driven Instability in Intense Charged Particle Beams betatron, plasma, simulation, focusing 558
  • E. Startsev, R.C. Davidson, H. Qin
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

In electrically neutral plasmas with strongly anisotropic distribution functions, free energy is available to drive different collective instabilities such as the electrostatic Harris instability and the transverse electromagnetic Weibel instability. Such anisotropies develop naturally in particle accelerators and may lead to a detoriation of beam quality. We have generalized the analysis of the classical Harris and Weibel instabilities to the case of a one-component intense charged particle beam with anisotropic temperature including the important effects of finite transverse geometry and beam space-charge. For a long costing beam, the delta-f particle-in-cell code BEST and the eighenmode code bEASt have been used to determine detailed 3D stability properties over a wide range of temperature anisotropy and beam intensity. A theoretical model is developed which describes the essential features of the linear stage of these instabilities. Both, the simulations and analytical theory, clearly show that moderately intense beams are linearly unstable to short-wavelength perturbations, provided the ratio of the longitudinal temperature to the transverse temperature is smaller than some threshold value.

MPPE004 Evaluation of Nonlinear Effects in the 3GeV Rapid Cycling Synchrotron of J-PARC resonance, sextupole, simulation, multipole 916
  • H. Hotchi, F. Noda, N. Tani
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • J. Kishiro, S. Machida, A.Y. Molodojentsev
    KEK, Ibaraki
  In order to accelerate an ultra-high intense beam with small particle losses, the 3GeV Rapid Cycling Synchrotron (RCS) of J-PARC, which is being constructed at JAERI, has a large acceptance. In this case the nonlinearity associated with the motion of particles at large amplitude and large momentum deviation plays a significant role. The sources of nonlinear magnetic fields in RCS are mainly connected with the fringe of the main dipole and quadrupole magnets and with the sextupole magnets used for the linear chromaticity correction. In this paper, we will present simulation results including such nonlinear effects. In addition, the possible correction scheme for the induced transverse resonances will be discussed.  
MPPE009 2003-2004 Nonlinear Optics Measurements and Modeling for the CERN SPS optics, simulation, multipole, quadrupole 1171
  • A. Faus-Golfe
    IFIC, Valencia
  • G. Arduini, F. Zimmermann
    CERN, Geneva
  • R. Tomas
    CELLS, Bellaterra (Cerdanyola del Vallès)
  In 2003 and 2004 nonlinear chromaticity, amplitude detuning, chromatic phase advance, resonance driving terms and off-energy orbits were measured in the CERN SPS at 14 GeV/c and 26 GeV/c, respectively. From the nonlinear chromaticity, the SPS optics model has been updated, by adjusting the strength of nonlinear field errors in dipoles and quadrupoles. Furthermore, we have added to the model the effect of the displacement of all main bends and the voluntary misalignments of all the other elements of the machine. We compare the field errors with those founded in 2002, 2001 and 2000. The tune shifts with transverse amplitude, driving terms, etc., predicted by this nonlinear optics model are compared with direct measurements.  
MPPE025 Dynamical Effects Due to Fringe Field of the Magnets in Circular Accelerators quadrupole, resonance, dynamic-aperture, multipole 1907
  • Y. Cai, Y. Nosochkov
    SLAC, Menlo Park, California
  Funding: Work supported by the Department of Energy under Contract No. DE-AC02-76SF00515.

The leading Lie generators, including the chromatic effects, due to hard edge fringe field of single multipole and solenoid are derived from the vector potentials within a Halmitonian system. These nonlinear generators are applied to the interaction region of PEP-II to analyze the linear errors due to the feed-down from the off-centered quadrupoles and solenoid. The nonlinear effects of tune shifts at large amplitude, the synchro-betatron sidebands near half integer and their impacts on the dynamic aperture are studied in the paper.

MPPE041 Orbit Stability at the Brazilian Synchrotron Light Source synchrotron, shielding, vacuum, quadrupole 2687
  • L. Liu, P.F. Tavares
    LNLS, Campinas
  A task force has been implemented at the Brazilian Synchrotron Light Laboratory to improve the beam orbit stability in the 1.37 GeV electron storage ring. The main problems faced during this year (2004) were due to the installation of a second RF cavity in the machine. We describe the main problems and the solutions that were implemented.  
MPPE062 Measurement and Optimization of Local Coupling from RHIC BPM Data coupling, injection, quadrupole, betatron 3553
  • R. Calaga, S. Abeytunge, M. Bai, W. Fischer
    BNL, Upton, Long Island, New York
  • F. Franchi
    GSI, Darmstadt
  • R. Tomas
    CELLS, Bellaterra (Cerdanyola del Vallès)
  Funding: U.S. Department of Energy.

Global coupling in RHIC is routinely corrected by using three skew quadrupole families to minimize the tune split. In this paper we aim to re-optimize the coupling at top energy by minimizing resonance driving terms and the C-matrix in two steps: 1. Find the best configuration of the three skew quadrupole families and 2. Identify locations with coupling sources by inspection of the driving terms and the C-matrix around the ring. The measurements of resonance terms and C-matrix are presented.

MPPE067 Refined Calculation of Beam Dynamics During UMER Injection injection, simulation, quadrupole, electron 3733
  • G. Bai, S. Bernal, T.F. Godlove, I. Haber, R.A. Kishek, P.G. O'Shea, B. Quinn, J.C. Tobin Thangaraj, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by U.S. Dept. of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

The University of Maryland Electron Ring (UMER) is built as a low-cost testbed for intense beam physics for benefit of larger ion accelerators. The beam intensity is designed to be variable, spanning the entire range from low current operation to highly space-charge-dominated transport. The ring has recently been closed and multi-turn commissioning has begun. Although we have conducted many experiments at high space charge during UMER construction, lower-current beams have become quite useful in this commissioning stage for assisting us with beam steering, measurement of phase advance, etc. One of the biggest challenges of multi-turn operation of UMER is correctly operating the Y-shaped injection section, hence called the Y-section, which is specially designed for UMER multi-turn operation. It is a challenge because the system requires several quadrupoles and dipoles in a very stringent space, resulting in mechanical, electrical, and beam control complexities. This paper presents a simulation study of the beam centroid motion in the injection region.

MPPE076 Design Study on a New Separator for PEEM3 electron, quadrupole, optics, focusing 3985
  • W. Wan, J. Feng, H.A. Padmore
    LBNL, Berkeley, California
  Funding: Work supported by the Director, Office of Energy Research, Office of Basic Energy Science, Material Sciences Division, U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.

A new aberration-corrected Photoemission Electron Microscope, called PEEM3, is under development at the Advanced Light Source. The resolution and transmission improvement is realized by correcting the lowest order spherical and chromatic aberrations using an electron mirror. A separator is required to separate the incoming uncorrected electron beam to the mirror from the corrected outgoing electron beam to the projector column. In this paper, we present a design study of a new separator for PEEM3. The layout, the Gaussian optics, the analysis of aberrations and the tolerance on power supply stability and alignment errors are reported.

MPPE081 The Comparison of a New Beam-Tracking Code to the Acceleration Test linac, acceleration, simulation, injection 4072
  • K. Yamamoto, S. Yamada, K. Yamamoto
    NIRS, Chiba-shi
  • T. Hattori
    RLNR, Tokyo
  • M. Okamura
    RIKEN, Saitama
  A new beam-tracking code using a 3D electro-magnetic field map of a linac is being developed. In this code, beam dynamics including non-linear and dipole effects can be easily estimated based on simulated field maps provided by commercial 3D analysis software. To verify the code, we manufactured an IH-linac and acceleration test of the linac was carried out with proton beam. The simulated results were compared with the tested acceleration performances.  
MPPE083 Harmonic Decomposition of Orbit Data for Multipole Analysis coupling, multipole, extraction, sextupole 4120
  • M.-J. Yang
    Fermilab, Batavia, Illinois
  The unprecedented position resolution provided by the newly commissioned Recycer BPM system is opening up a new chapter of beam based multipole analysis at Fermilab. The closed orbit data, taken with circulating beam and averaged over many consecutive turns, has been shown to have the resolution of a few microns. The result of polynomial fit to BPM position data, as a function of dipole kick sizes, is used to separate orbit data into first, second, and third order. Combining both the in-plane and cross-plane orbit data it is possible to determine the multipole content within each half cell. This paper presents the algorithm behind the procedure, the data collected from the Fermilab Recycler Ring, and the final analysis result.  
MPPE084 Multipole error Analysis Using Local 3-Bump Orbit Data in Fermilab Recycler coupling, multipole, quadrupole, closed-orbit 4144
  • M.-J. Yang, M. Xiao
    Fermilab, Batavia, Illinois
  The magnetic harmonic errors of the Fermilab Recycler ring were examined using circulating beam data taken with closed local orbit bumps. Data was first parsed into harmonic orbits of first, second, and third order. Each of which was analyzed for sources of magnetic errors of corresponding order. This study was made possible only with the incredible resolution of a new BPM system that was commissioned after June of 2003.  
MPPP006 Performance Calculation on Orbit Feedback for NSLSII feedback, power-supply, closed-orbit, ground-motion 1036
  • L.-H. Yu
    BNL, Upton, Long Island, New York
  We discuss the preliminary calculation on the performance of closed orbit feedback system for NSLSII, its relation to the requirement on BPM, floor and girder stability, power supply stability, etc.  
MPPP010 Feedback to Suppress Phase Noise at Aladdin feedback, simulation, damping, synchrotron 1180
  • R.A. Bosch, K. Jacobs, K. J. Kleman
    UW-Madison/SRC, Madison, Wisconsin
  The performance of the Aladdin infrared beamline is adversely affected by a Robinson mode in which all bunches move in unison with a frequency of 3 kHz. To decrease these oscillations, feedback has been installed in the radiofrequency system to damp longitudinal motion of the bunch centroids. Simulations indicate that at frequencies around 3 kHz, the phase noise generated by Robinson modes may be reduced 20 dB by feedback with a damping time of 0.3 ms. This agrees with the measured performance of feedback circuitry. Since the feedback greatly improves operation of the infrared beamline, it is now incorporated into the standard operation of Aladdin.  
MPPP012 First-Principles Simulation and Comparison with Beam Tests for Transverse Instabilities and Damper Performance in the Fermilab Main Injector simulation, damping, injection, betatron 1300
  • D.J. Nicklaus, G.W. Foster, V.S. Kashikhin
    Fermilab, Batavia, Illinois
  An end-to-end performance calculation and comparison with beam tests was performed for the bunch-by-bunch digital transverse damper in the Fermilab Main Injector. Time dependent magnetic wakefields responsible for "Resistive Wall" transverse instabilities in the Main Injector were calculated with OPERA-2D using the actual beam pipe and dipole magnet lamination geometry. The leading order dipole component was parameterized and used as input to a bunch-by-bunch simulation which included the filling pattern and injection errors experienced in high-intensity operation of the Main Injector. The instability growth times, and the spreading of the disturbance due to newly mis-injected batches was compared between simulations and beam data collected by the damper system. Further simulation models the effects of the damper system on the beam.  
MPPP022 The Impedance of Selected Components of the Synchrotron Light Source Petra III impedance, vacuum, synchrotron, insertion 1751
  • R. Wanzenberg, K. Balewski
    DESY, Hamburg
  At DESY it is planned to convert the PETRA ring into a synchrotron radiation facility, called PETRA III, in 2007. Since the impedance of the machine determines its performance with respect to coupled and single bunch instabilities it is important to know the wakefields and higher order modes (HOMs) of the different components of the vacuum system. Numerical calculations of wakefields and HOMs are presented for several components of PETRA III, including the rf-cavities, shielded bellows and tapered vacuum chamber transitions. The impedance of these components is presented in terms of the loss and kick parameters.  
MPPP031 The CERN-SPS Experiment on Microwave Transmission Through the Beam Pipe electron, cyclotron, resonance, injection 2212
  • T. Kroyer, T. Kroyer
    TU Vienna, Vienna
  • F. Caspers, E. Mahner
    CERN, Geneva
  Funding: Ministry for Education, Science and Culture, Austria.

In the CERN SPS microwave transmission measurements through beampipe sections with a length of 30 m and 7 m meter respectively have been carried out in the frequency range 2-4 GHz since spring 2003. Here we report on new results obtained with improved measurement techniques during the 2004 run. Observation techniques include a fast real time scope, spectrum analyser IF and video output signal registration and baseband signal observation using a PC soundcard. The unexpected beam induced amplitude modulation has been confirmed on all kinds of available beams including single bunches. It was found that there is a correlation between the amount of beam induced signal attenuation and the beam losses registered by external scintillators. Potential theoretical models are discussed.

MPPP045 Two Dimensional Aspects of the Regenerative BBU in Two-Pass Recirculating Accelerators recirculation, polarization, insertion, higher-order-mode 2872
  • E.P. Pozdeyev
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by DOE Contract DE-AC05-84ER40150.

In this paper, I present the formula, describing a threshold of the regenerative multi-pass Beam Breakup (BBU) for a single dipole higher order mode with arbitrary polarization in a two-pass accelerator with a general-form, 4x4 recirculation matrix. To illustrate specifics of the BBU in two dimensions, the formula is used to calculate the threshold for the reflecting and rotating optics of the recirculator that can lead to higher threshold currents. Then, I present a mathematical relation between transfer matrices between cavities of the accelerating structure and recirculation matrices for each cavity, which must be satisfied in order to successfully suppress the BBU by reflection or rotation in several cavities. At the end of the paper, a fast, two-dimensional BBU code developed at the Jefferson Lab is described.

MPPP051 Transverse Impedance of Two-Layer Tube impedance, vacuum, multipole, undulator 3138
  • M. Ivanyan, A.V. Tsakanian
    CANDLE, Yerevan
  The exact analytical expressions for the multipole longitudinaland transverse impedances of two-layer tube with finite wall thickness areobtained. The numerical examples for the impedances of the vacuum chamberwith laminated walls are given.  
  • N. Li
    SLAC, Menlo Park, California
  • F. Huang, H. Qu
    IHEP Beijing, Beijing
  Funding: DOE National Institutes of Health.

Few problems occurred during the SPEAR3 magnets production at IHEP, China. It was very hard to find resolution from existing knowledge of those problems. It was possible that similar problems might happen in building accelerator magnet in other institutes before, but they were not addressed in public papers. Those problems were discussed and solved by engineers from both SSRL and IHEP after conducting certain experiments. Traditionally, the magnet design and measurement data have been always well documented and addressed in the papers, but the production experiences have not been recorded adequately. It is the goal of this paper to record the problems and their resolutions during SPEAR3 magnet production, which will certainly benefit future magnet projects.

MPPT004 End Chamfer Study and Field Measurements of the BEPCII Dipoles multipole, sextupole, quadrupole, factory 919
  • W. Chen, C. Cao, C. Shi, Z. Yin
    IHEP Beijing, Beijing
  The new BEPCII double ring will be added in the existing BEPC tunnel. There are more than 40 bending magnets named 67B in the new ring. The 67B is conventional ‘C’-type dipole magnet. The magnetic filed properties are dominated by the magnet end effect. The end effect have been studied and minimized by a proper end chamfer. Magnetic measurements of the prototype and productions were carried out using long coil. The developing process of the pole end chamfers and the measurement results of the 67B prototype and batch productions are described in the paper.  
MPPT010 A New Correction Magnet Package for the Fermilab Booster Synchrotron quadrupole, sextupole, booster, multipole 1204
  • V.S. Kashikhin, D.J. Harding, J.A. John, J.R. Lackey, A. Makarov, W. Pellico, E. Prebys
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-76CH03000.

Since its initial operation over 30 years ago, most correction magnets in the Fermilab Booster Synchrotron have only been able to fully correct the orbit, tunes, coupling, and chromaticity at injection (400MeV). We have designed a new correction package, including horizontal and vertical dipoles, normal and skew quadrupoles, and normal and skew sextupoles, to provide control up to the extraction energy (8GeV). In addition to tracking the 15Hz cycle of the main, combined function magnets, the quadrupoles and sextupoles must swing through their full range in 1ms during transition crossing. The magnet is made from 12 water-cooled racetrack coils and an iron core with 12 poles, dramatically reducing the effective magnet air gap and increasing the corrector efficiency. Magnetic field analyses of different combinations of multipoles are included.

MPPT016 Beam Injection for the PF-AR with a Single Pulsed Quadrupole Magnet injection, quadrupole, kicker, emittance 1517
  • K. Harada, Y. Kobayashi, T. Mitsuhashi, T. Miyajima, S. Nagahashi, T. Obina, A. Ueda
    KEK, Ibaraki
  We develop the injection system for PF-AR (Photon Factory Advanced Ring for Pulsed X-ray) with single pulse quadrupole (PQ) magnet without pulse local bump of the stored beam with four dipole kickers. The pulse quadrupole magnet has the length of 30cm, the field gradient of 3T/m, half-sine-form pulse width of 2.4mSec, measured inductance of 1.8mH and the peak current of about 2000A. With this magnet, the amplitude of the injected beam can be reduced to about the half of that only with septum magnets and the reduced amplitude is almost the same as the case of the usual injection with the pulse bump of the stored beam. We installed PQ-magnet at the short straight section near the south symmetric point of PF-AR in this summer of 2004 and succeeded to inject beam to the storage ring during the machine study in autumn, 2004.  
MPPT019 Magnet Design for the ISIS Second Target Station Proton Beam Line target, quadrupole, proton, septum 1652
  • C.M. Thomas, D.C. Faircloth, S.J.S. Jago
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  The ISIS facility, based at the Rutherford Appleton Laboratory in the UK, is an intense source of neutrons and muons for condensed matter research. The accelerator facility delivers an 800 MeV proton beam of 2.5x1013 protons per pulse at 50 Hz to the present target station. As part of a facility upgrade, it is planned to share the source with a second, 10 Hz, target station. The beam line supplying this target will extract from the existing target station beam line. Electromagnetic Finite Element Modelling techniques have been used to design the magnets required to meet the specified beam line optics. Kicker, septum, dipole, quadrupole, and steering magnets are covered. The magnet design process, involving 2D and 3D modelling, the calculation of ideal shims and chamfers, choice of steel, design of conducting coils, handling of heating issues and eddy current effects, is discussed.  
MPPT024 Rotating Coil Magnetic Measurement System and Measurement Results of Quadrupole Prototype for BEPCII Storage Ring quadrupole, multipole, pick-up, storage-ring 1844
  • L. Li, W. Chen, G. Ni, X.J. Sun
    IHEP Beijing, Beijing
  A normal quadrupole prototype magnet with 266-mm long, 105-mm aperture has been designed and fabricated by IHEP. Total of 88 quadrupole magnets are under fabrication. The multipole components, magnetic field gradient and transfer function of the quadrupole magnets were measured in September 2004, using an updated measurement system, which includes a rotating coil measurement system and a Hall probe measurement system. This paper mainly describes the updated harmonic coil magnetic field measurement system and provides the measurement results for BEPC II quadrupole magnets.  
MPPT028 An Air Bearing Rotating Coil Magnetic Measurement System quadrupole, resonance, multipole, permanent-magnet 2038
  • S.C. Gottschalk, K.W. Kangas, D.J. Taylor, W.J. Thayer
    STI, Washington
  This paper describes a rotating coil magnetic measurement system supported on air bearings. The design is optimized for measurements of 0.1micron magnetic centerline changes on long, small aperture quadrupoles. Graphite impregnated epoxy resin is used for the coil holder and coil winding forms. Coil holder diameter is 11 mm with a length between supports of 750mm. A pair of coils is used to permit quadrupole bucking during centerline measurements. Coil length is 616mm, inner radius 1.82mm, outer radius 4.74mm. The key features of the mechanical system are simplicity; air bearings for accurate, repeatable measurements without needing warm up time and a vibration isolated stand that uses a steel-topped Newport optical table with air suspension. Coil rotation is achieved by a low noise servo motor controlled by a standalone Ethernet servo board running custom servo software. Coil calibration procedures that correct wire placement errors, tests for mechanical resonances, and other system checks will also be discussed.  
MPPT031 Radiation Resistant Magnets for the RIA Fragment Separator radiation, target, quadrupole, sextupole 2200
  • A. Zeller, V. Blideanu, R.M. Ronningen, B. Sherrill
    NSCL, East Lansing, Michigan
  • R.C. Gupta
    BNL, Upton, Long Island, New York
  Funding: Supported in part by Michigan State University and the U.S. DOE.

The high radiation fields around the production target and the beam dump in the fragment separator at the Rare Isotope Accelerator requires that radiation resistant magnets be used. Because large apertures and high gradients are required for the quadrupoles and similar demanding requirements for the dipole and sextupoles, resistive coils are difficult to justify. The radiation heating of any materials at liquid helium temperatures also requires that superconducting versions of the magnets have low cold-masses. The final optical design has taken the practical magnets limits into account and sizes and fields adjusted to what is believed to be achievable with technology that is possible with sufficient R&D. Designs with higher obtainable current densities and having good radiation tolerances that use superconducting coils are presented, as well as the radiation transport calculations that drive the material parameters.

MPPT040 The LHC Magnetic Field Model injection, coupling, sextupole, superconducting-magnet 2648
  • N.J. Sammut, L. Bottura
    CERN, Geneva
  • J. Micallef
    University of Malta, Faculty of Engineering, Msida
  The compensation of the dynamic field changes during the proton and ion beam injection and acceleration in the LHC requires an accurate forecast and an active control of the magnetic field in the accelerator. The LHC Magnetic Field Model is the core of this magnetic prediction system. This open loop control scheme will provide the desired field components at a given time, magnet operating current, magnet ramp-rate, magnet temperature and magnet powering history to the required precision. The model is based on the identification and physical decomposition of the effects that contribute to the total field in the magnet aperture of the LHC dipoles. By using data obtained from series measurements, these components are then quantified theoretically or empirically depending on the complexity of the physical phenomena involved. This paper presents the developments of the newly fine-tuned magnetic field model and evaluates its accuracy, reproducibility and predicting capabilities.  
MPPT041 Improvement of the Geometrical Stability of the LHC Cryodipoles when Blocking the Central Support Post vacuum, superconducting-magnet, laser, alignment 2675
  • F. Seyvet, J. Beauquis, E.D. Fernandez Cano, J.-B. Jeanneret, A. Poncet, D. Tommasini
    CERN, Geneva
  The LHC will be composed of 1232 horizontally curved 16 meter long super-conducting dipole magnets cooled at 1.9K, supported within their vacuum vessel by three Glass Fiber Resin Epoxy (GFRE) support posts. The two support posts at the dipole extremities were initially designed free to slide longitudinally with respect to the vacuum vessel and the central support post was designed free to slide transversally. However the magnet shape did not retain the tight geometrical tolerances, of the order of fractions of mm, imposed by machine aperture and magnetic corrector centering requirements. Thereafter a modification to the supporting system, removing the initial transversal degree of freedom of the lower flange of the central support post with respect to the vacuum vessel, was designed and implemented. This paper describes the design of the magnet/cryostat interface with and without blockage of the central support post, analyzes the additional mechanical loads related to the modification and reviews the experimental results with respect to the requirements for beam aperture and magnetic corrector centering.  
MPPT042 Field Quality and Alignment of the Series Produced Superconducting Matching Quadrupoles for the LHC Insertions quadrupole, multipole, insertion, alignment 2738
  • N. Catalan-Lasheras, G. Kirby, R. Ostojic, J.C. Perez, H. Prin, W.  Venturini Delsolaro
    CERN, Geneva
  The production of the superconducting quadrupoles for the LHC insertions is advancing well and about half of the magnets have been produced. The coil size and field measurements performed on individual magnets both in warm and cold conditions are yielding significant results. In this paper we present the procedures and results of steering the series production at the magnet manufacturers and the assembly of cold masses at CERN. In particular, we present the analysis of warm-cold correlations and hysteresis of the main field multipoles, the correlation between coil sizes and geometrical field errors and the effect of permeability of magnet collars. The results are compared with the target errors for field multipoles and alignment.  
MPPT043 Low-Beta Quadrupole Designs for the LHC Luminosity Upgrade quadrupole, luminosity, insertion, multipole 2795
  • R. Ostojic, N. Catalan-Lasheras, G. Kirby
    CERN, Geneva
  Several candidate scenarios are considered for the upgrade of the LHC insertions in view of increasing the luminosity in excess of 1034 cm-2s-1. In all cases, superconducting low-beta quadrupoles with apertures in the range of 90-110 mm are required in view of increased heat loads and beam crossing angles. We present possible low-beta quadrupole designs based on Nb3Sn and NbTi superconducting cables, including existing LHC-class superconductors, present scaling laws for the magnet parameters and discuss relative advantages of the underlying triplet layouts.  
MPPT044 The Construction of the Low-Beta Triplets for the LHC quadrupole, multipole, insertion, vacuum 2798
  • R. Ostojic, M. Karppinen, T.M. Taylor, W.  Venturini Delsolaro
    CERN, Geneva
  • R. Bossert, J. DiMarco, SF. Feher, J.S. Kerby, M.J. Lamm, T.H. Nicol, A. Nobrega, T.M. Page, T. Peterson, R. Rabehl, P. Schlabach, J. Strait, C. Sylvester, M. Tartaglia, G. Velev
    Fermilab, Batavia, Illinois
  • N. Kimura, T. Nakamoto, T. Ogitsu, N. Ohuchi, t.s. Shintomi, K. Tsuchiya, A. Yamamoto
    KEK, Ibaraki
  The performance of the LHC depends critically on the low-beta triplets, located on either side of the four interaction points. Each triplet consists of four superconducting quadrupole magnets, which must operate reliably at up to 215 T/m, sustain extremely high heat loads and have an excellent field quality. A collaboration of CERN, Fermilab and KEK was set up in 1996 to design and build the triplet systems, and after nine years of joint effort the production will be completed in 2005. We retrace the main events of the project and present the design features and performance of the low-beta quadrupoles, built by KEK and Fermilab, as well as of other vital elements of the triplet. The experience in assembly of the first triplet at CERN and plans for tunnel installation and commissioning in the LHC are also presented. Apart from the excellent technical results, the construction of the LHC low-beta triplets has been a highly enriching experience combining harmoniously the different competences and approaches to engineering in a style reminiscent of physics experiment collaborations, and rarely before achieved in accelerator building.  
MPPT046 Superconducting Helical Snake Magnet for the AGS resonance, magnet-design, proton, acceleration 2935
  • E. Willen, M. Anerella, J. Escallier, G. Ganetis, A. Ghosh, R.C. Gupta, M. Harrison, A.K. Jain, A.U. Luccio, W.W. MacKay, A. Marone, J.F. Muratore, S.R. Plate, T. Roser, N. Tsoupas, P. Wanderer
    BNL, Upton, Long Island, New York
  • M. Okamura
    RIKEN, Saitama
  Funding: DOE

A superconducting helical magnet has been built for polarized proton acceleration in the Brookhaven AGS. This "partial Snake" magnet will help to reduce the loss of polarization of the beam due to machine resonances. It is a 3 T magnet some 1940 mm in magnetic length in which the dipole field rotates with a pitch of 0.2053 degrees/mm for 1154 mm in the center and a pitch of 0.3920 degrees/mm for 393 mm in each end. The coil cross-section is made of two slotted cylinders containing superconductor. In order to minimize residual offsets and deflections of the beam on its orbit through the Snake, a careful balancing of the coil parameters was necessary. In addition to the main helical coils, a solenoid winding was built on the cold bore tube inside the main coils to compensate for the axial component of the field that is experienced by the beam when it is off-axis in this helical magnet. Also, two dipole corrector magnets were placed on the same tube with the solenoid. A low heat leak cryostat was built so that the magnet can operate in the AGS cooled by several cryocoolers. The design, construction and performance of this unique magnet will be summarized.

MPPT048 Test Results of HTS Coil and Magnet R&D for RIA quadrupole, radiation, superconductivity, superconducting-magnet 3016
  • R.C. Gupta, M. Anerella, M. Harrison, W. Sampson, J. Schmalzle
    BNL, Upton, Long Island, New York
  • A. Zeller
    NSCL, East Lansing, Michigan
  Funding: Work supported by the U.S. Department of Energy and by the National Science Foundation.

Brookhaven National Laboratory is developing quadrupole magnets for the proposed Rare Isotope Accelerator (RIA) based on commercially available High Temperature Superconductors (HTS). These quadrupoles will be used in the Fragment Separator region and are one of the more challenging elements in the RIA proposal. They will be subjected to several orders of magnitude more energy and radiation deposition than typical beam line and accelerator magnets receive during their entire lifetime. The proposed quadrupoles will operate in the 20-40 K temperature range for efficient heat removal. HTS coils that have been tested so far indicate that the coils meet the magnetic field requirements of the design. We will report the test results of about 10 HTS coils and of a magnetic mirror configuration that simulates the magnetic field and Lorentz force in the proposed quadrupole. In addition, the preliminary design of an HTS dipole magnet for the Fragment Separator region will also be presented.

MPPT049 Optimization of Open Midplane Dipole Design for LHC IR Upgrade luminosity, optics, radiation, quadrupole 3055
  • R.C. Gupta, M. Anerella, A. Ghosh, M. Harrison, J. Schmalzle, P. Wanderer
    BNL, Upton, Long Island, New York
  • N.V. Mokhov
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886.

The proposed ten-fold increase in Large Hadron Collider (LHC) luminosity requires high field (~15 T) magnets that are subjected to the high radiation power of ~9 kW/per beam directed towards each interaction region. This has a major impact in the design of first dipole in the "Dipole First" optics. The proposed design allows sufficient clear space between coils so that most of the particle showers from the interaction points (concentrated at the midplane due to strong magnetic field) can be transported outside the coil region to a warm absorber thus drastically reducing the peak power density in the coils and removing heat at a higher (nitrogen) temperature. The concept, however, presents several new technical challenges: (a) obtaining good field quality despite a large midplane gap, (b) minimizing peak fields on coil, (c) dealing with large vertical forces with no structure between the coils, (d) minimizing heat deposition in the cold region, (e) designing a support structure. Designs with different horizontal and vertical coil spacing are presented that offer significant savings in the operating and infrastructure cost of the cryo-system, providing reliable quench-stable operation with a lifetime of the critical components of at least ten years.

MPPT050 Test Results for LHC Insertion Region Dipole Magnets quadrupole, sextupole, insertion, octupole 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.

MPPT051 Reshimming of Tevatron Dipoles; A Process-Quality and Lessons-Learned Perspective quadrupole, controls, background, gun 3156
  • J.N. Blowers, R. Hanft, D.J. Harding, J.A. John, W.F. Robotham
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-76CH03000.

Over the last two years corrections have been made for the skew quadrupole moment in 530 of the 774 installed dipoles in the Tevatron. This process of modifying the magnets in situ has inherent risk of degrading the performance of the superconducting accelerator. In order to manage the risk, as well as to ensure the corrections were done consistently, formal quality tools were used to plan and verify the work. The quality tools used to define the process and for quality control are discussed, along with highlights of lessons learned.

MPPT053 Restoring the Skew Quadrupole Moment in Tevatron Dipoles quadrupole, coupling, betatron 3244
  • D.J. Harding, P. Bauer, J.N. Blowers, J. DiMarco, H.D. Glass, R. Hanft, J.A. John, W.F. Robotham, M. Tartaglia, J. Tompkins, G. Velev
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-76CH03000.

In early 2003 it was realized that mechanical changes in the Tevatron dipoles had led to a deterioration of the magnetic field quality that was hindering operation of the accelerator. After extensive study, a remediation program was started in late 2003 which will continue through 2005. The mechanical and magnetic effects are discussed. The readjustment process and experience are reported, along with other observations on aging magnets.

MPPT056 First Ideas Towards the Super-Conducting Magnet Design for the HESR at FAIR quadrupole, magnet-design, sextupole, antiproton 3354
  • R. Eichhorn, F.M. Esser, A. Gussen, S. Martin
    FZJ, Julich
  The Forschungszentrum Juelich has taken the leadership of a consortium being responsible for the design of the HESR going to be part of the FAIR project at GSI. The HESR is a 50 Tm storage ring for antiprotons, based on a super-conducting magnet technology. On basis of the RHIC Dipole D0 (3.6 T), the magnet design for the HESR has started recently. One key issue will be a very compact layout because of the rather short magnets (been 1.82 m for the dipoles and 0.5 m for the other magnets). This paper will present first ideas of the magnetic and cryogenic layout, give a status report on the achievements so far and discuss the need and possible solutions for a bent magnet with a radius of curvature of 13.2 m.  
MPPT057 Design of a Magnet System for a Muon Cooling Ring closed-orbit, lattice, dynamic-aperture, simulation 3366
  • S.A. Kahn, H.G. Kirk
    BNL, Upton, Long Island, New York
  • D. Cline, A.A. Garren
    UCLA, Los Angeles, California
  • F.E. Mills
    Fermilab, Batavia, Illinois
  Funding: This work was performed with the support of the U.S. DOE under Contract No. DE-AC02-98CH10886.

A hydrogen gas filled muon cooling ring appears to be a promising approach to reducing the emittance of a muon beam for use in a neutrino factory or a muon collider. A small muon cooling ring is being studied to test the feasibility of cooling by this method. This paper describes the magnet system to circulate the muons. The magnet design is optimized to produce a large dynamic aperture to contain the muon beam with minimum losses. Muons are tracked through the field to verify the design.

MPPT061 Ideal Wiggler wiggler, quadrupole, emittance, focusing 3511
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  Described is the wiggler with reduced nonlinear components for usage in damping ring of Linear Collider. Zigzag field dependence on longitudinal coordinate made by profiling of poles.  
MPPT067 Stray Field Reduction in ALS Eddy Current Septum Magnets septum, storage-ring, injection, extraction 3718
  • D. Shuman, W. Barry, S. Prestemon, R.D. Schlueter, C. Steier, G.D. Stover
    LBNL, Berkeley, California
  Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

Stray field from an eddy current septum magnet adversely affects the circulating beam and can be reduced using several techniques. The stray field time history typically has a fast rise section followed by a long exponential decay section when pulsed with a half sine drive current. Changing the drive current pulse to a full sine has the effect of both reducing peak stray field magnitude by ~3x, and producing a quick decay from this peak to a lower field level which then has a similar long decay time constant as that from the half sine only drive current pulse. A method for tuning the second half sine (reverse) drive current pulse to eliminate the long exponential decay section is given.

MPPT072 3D Simulation Studies of SNS Ring Doublet Magnets simulation, SNS, quadrupole, multipole 3865
  • J.-G. Wang
    ORNL, Oak Ridge, Tennessee
  • N. Tsoupas
    BNL, Upton, Long Island, New York
  • M. Venturini
    LBNL, Berkeley, California
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The accumulator ring of the Spallation Neutron Source (SNS) at ORNL employs in its straight sections closely packed quadrupole doublet magnets with large aperture of R=15.1 cm and relatively short iron-to-iron distance of 51.4 cm.* The magnetic interference among the magnets in the doublet assemblies is not avoidable due to the fringe fields. Though each magnet in the assemblies has been individually mapped to high accuracy of delta(B)/B~1x10-4, the experimental data including the magnet interference effect in the assemblies will not be available. We have performed 3D computer simulations on a quadrupole doublet model in order to assess the degree of the interference and to obtain relevant data which should be very useful for the SNS commissioning and operation. This paper reports our simulation results.

*N. Tsoupas et al. "A Large-aperture Narrow Quadrupole for the SNS Accumulator Ring," Proc. EPAC 2002, p.1106, Paris, June 3-7, 2002.

MPPT073 Field Distribution of Injection Chicane Dipoles in SNS Ring simulation, multipole, SNS, injection 3907
  • J.-G. Wang
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

3D computing simulations have been performed to study the magnetic field distribution of the injection chicane dipoles in the SNS ring.* The simulation studies have yielded the performance characteristics of the magnets and generated the magnetic field data in three dimensional grids, which can be used for detailed investigation of beam dynamics. Based on the simulation data, a 3D multipole expansion of the chicane dipole field, consisting of generalized gradients and their derivatives, has been made. The harmonic and pseudo-harmonic components in the expansion give much insight into the magnet physics. The expansion is quasi-analytical by fitting numeric data into a few interpolation functions. A 5th-order representation of the field is generated, and the effects of even higher order terms on the field representation are discussed.

*The injection chicane dipoles were designed at BNL by Y.Y. Lee, W. Meng, et al. See "Injection into the SNS Accumulator Ring: Minimizing Uncontrolled Losses and Dumping Stripped Electrons," D.T. Abell, Y.Y. Lee, W. Meng, EPAC 2000.

MPPT076 Conceptual Designs of Magnet Systems for the Taiwan Photon Source sextupole, storage-ring, quadrupole, vacuum 3979
  • C.-H. Chang, H.-H. Chen, T.-C. Fan, M.-H. Huang, C.-S. Hwang, J.C. Jan, W.P. Li, F.-Y. Lin, H.-C. Su
    NSRRC, Hsinchu
  The National Synchrotron Radiation Research Center (NSRRC) at Taiwan is designing a 3.0 GeV energy with ultra-low emittance storage ring for new Taiwan Photon Source (TPS) project. The storage has a circumference of 514 m with 24 periods of double-bend achromatic magnet system. The conceptual designs for each magnet family for the storage ring are optimize for operation of electron energy at 3.0- 3.3 GeV. This paper reviews the preliminary design and the key accelerator magnet issues.  
MPPT084 Dipole and Quadrupole Magnets for the Duke FEL Booster Injector quadrupole, booster, simulation, lattice 4147
  • S. Mikhailov
    DU/FEL, Durham, North Carolina
  • N. Gavrilov, D.G. Gurov, O.B. Kiselev, A.B. Ogurtsov, E.R. Rouvinsky, K.Zh. Zhiliaev
    BINP SB RAS, Novosibirsk
  Funding: This work is supported by U.S. DOE grant # DE-FG02-01ER41175 and by AFOSR MFEL grant # F49620-001-0370.

The full energy booster injector for the Duke FEL storage ring is presently under installation. The booster is designed to provide continuous injection into the Duke FEL storage ring in the top-off mode at the energy variable from 270 MeV to 1.2 GeV. The magnetic elements for the booster have been fabricated and magnetically measured in the Budker Institute of Nuclear Physics, Russia. The paper presents magnetic and mechanical design of the booster dipole and quadrupole magnets and results of their magnetic measurements. Results of simulation of the booster lattice taking into account residual field and non-linearity of the magnets are also presented.

MPPT086 Conventional Magnets Design for the Candle Storage Ring quadrupole, simulation, sextupole, storage-ring 4182
  • V.G. Khachatryan, A. Petrosyan
    CANDLE, Yerevan
  The lattice of 216m long CANDLE storage ring (16 Double Bend Achromat cells) will contain 32 gradient dipole magnets, 80 quadrupole magnets of three types and two types of 64 sextupole magnets. Magnetic as well as mechanical design of those magnets has been performed relying on extensive world experience. Computer simulations and large volume of computations have been carried out to design magnets that conform to strict requirements.  
TOAA001 Limits of Nb3Sn Accelerator Magnets superconducting-magnet, accumulation 107
  • S. Caspi, P. Ferracin
    LBNL, Berkeley, California
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

Pushing accelerator magnets beyond 10T holds a promise of future upgrades to machines like the Tevatron at FermiLab and the LHC at CERN. Exhausting the current density limits of NbTi, superconductor, Nb3Sn is at the present time the only practical superconductor capable of generating fields beyond 10T. Several Nb3Sn pilot magnets, with fields as high as 16T, have been built and tested, paving the way for future attempts at fields approaching 20T. The combination of high current density and the required high magnetic fields has resulted in reduced conductor volume and significantly increased the accumulated Lorentz forces. Future coil and structure designs will be required to deal with stresses of several 100’s of MPa and forces of 10’s of MN/m. The combined engineering requirements on size and cost of accelerator magnets will require a magnet technology that diverges from the one currently used with NbTi conductor. How far can the engineering of high field magnets be pushed, what are the issues and limitations, and what tools will we need before such magnets can be used in particle accelerators. In this paper we shall address such issues and attempt to provide possible answers.

TOAA002 U.S. Accelerator Contribution to the LHC quadrupole, alignment, luminosity, interaction-region 184
  • M.J. Lamm
    Fermilab, Batavia, Illinois
  In 1998, the United States entered into an agreement with CERN to help build the Large Hadron Collider (LHC), with contributions to the accelerator and to the large HEP detectors. To accomplish this, the US LHC Accelerator Project was formed, encompassing expertise from Brookhaven National Laboratory, Fermi National Accelerator Laboratory and the Lawrence Berkeley National Laboratory. Contributions from the US LHC Accelerator project included superconducting high gradient quadrupoles and beam separation dipoles for the four interaction regions and the RF section; feedboxes for cryogenic, power and instrumentation distribution; neutral and hadron beam absorbers in the high luminosity regions; design of the inner triplet cryogenic system; beam tracking studies utilizing the design IR magnet field quality and magnet alignment; particle heat deposition studies in the IR’s; and short sample characterization of superconducting cables used in the arc dipoles and quadrupoles. This report is a summary of these contributions including the progress towards project completion, as well as a discussion of future plans for US participation in the LHC accelerator.  
TOAA004 Field Quality Study in Nb3Sn Accelerator Magnets sextupole, quadrupole, alignment 366
  • V. Kashikhin, G. Ambrosio, N. Andreev, E. Barzi, R. Bossert, J. DiMarco, V.S. Kashikhin, M.J. Lamm, I. Novitski, P. Schlabach, G. Velev, R. Yamada, A.V. Zlobin
    Fermilab, Batavia, Illinois
  Funding: This work was supported by the U.S. Department of Energy.

High field accelerator magnets are being developed at Fermilab for present and next generation hadron colliders. These magnets are designed for a nominal field of 10-12 T in the magnet bore of 40-50 mm and an operating temperature of 4.5 K. To achieve these design parameters, a new, high-performance Nb3Sn superconducting strand is used. Four short Nb3Sn dipole models of the same design based on a single-bore cos-theta coil and a cold iron yoke have been fabricated and tested at Fermilab. Their field quality was measured at room temperature during magnet fabrication and at helium temperature. This paper reports the results of warm and cold magnetic measurements. The systematic geometrical harmonics and their RMS spread due to cross-section imperfections, the coil magnetization effects caused by persistent currents in superconductor and eddy current in the cable, the "snap-back" effect at injection and the iron saturation effect at high fields are presented and compared with theoretical predictions.

TOAA006 Development of Superconducting Combined Function Magnets for the Proton Transport Line for the J-PARC Neutrino Experiments proton, quadrupole, alignment, target 495
  • T. Nakamoto, Y. Ajima, Y. Fukui, N. Higashi, A. Ichikawa, N. Kimura, T. Kobayashi, Y. Makida, T. Ogitsu, H. Ohhata, T. Okamura, K. Sasaki, M. Takasaki, K. Tanaka, A. Terashima, T. Tomaru, A. Yamamoto
    KEK, Ibaraki
  • M. Anerella, J. Escallier, G. Ganetis, R.C. Gupta, M. Harrison, A.K. Jain, J.F. Muratore, B. Parker, P. Wanderer
    BNL, Upton, Long Island, New York
  • T. Fujii, E. Hashiguchi, T. Kanahara, T. Orikasa
    Toshiba, Yokohama
  • Y. Iwamoto
    JAERI, Ibaraki-ken
  • T. Obana
    GUAS/AS, Ibaraki
  A second generation of long-baseline neutrino oscillation experiments has been proposed as one of the main projects at J-PARC jointly built by JAERI and KEK. Superconducting combined function magnets, SCFMs, will be utilized for the 50 GeV, 750 kW proton beam line for the neutrino experiment and an R&D program is in underway at KEK. The magnet is designed to provide a combined function of a dipole field of 2.6 T with a quadrupole field of 19 T/m in a coil aperture of 173.4 mm. A series of 28 magnets in the beam line will be operated DC in supercritical helium cooling below 5 K. A design feature of the SCFM is the left-right asymmetry of the coil cross section: current distributions for superimposed dipole- and quadrupole- fields are combined in a single layer coil. Another design feature is the adoption of glass-fiber reinforced phenolic plastic spacers to replace the conventional metallic collars. To evaluate this unique design, fabrication of full-scale prototype magnets is in progress at KEK and the first prototype will be tested at cold soon. This paper will report the development of the SCFMs.  
TOAA008 Progress and Status in SNS Magnet Measurements at ORNL quadrupole, SNS, linac, permanent-magnet 609
  • T. Hunter, SH. Heimsoth, DL. Lebon, RM. McBrien, J.-G. Wang
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The Spallation Neutron Source (SNS) contains more than 600 magnets. Among them, about 400 magnets for the Linac and transfer lines are being measured on site at Oak Ridge National Laboratory. These magnets include Permanent Magnet Quadrupoles, Electro-magnetic Quadrupoles, Dipoles and Correctors. The Permanent Magnet Quadrupoles are installed in the Drift Tube Linac (DTL) and are the only Permanent Magnets in the machine. These measurements are for magnets installed in the DTL, Coupled Cavity Linac (CCL), Superconducting Linac (SCL), High Energy Beam Transport (HEBT), and the Ring to Target Beam Transport (RTBT) line. All magnets have met specifications. Approximately three fourths of the magnets have so far been measured and installed. This presentation outlines the magnet measurements for SNS at ORNL and overviews the activities and accomplishments to date.

TOAA009 Recent Test Results of the Fast-Pulsed 4 T COSO Dipole GSI 001 coupling, sextupole, synchrotron, injection 683
  • G. Moritz, J. Kaugerts
    GSI, Darmstadt
  • B. Auchmann, S. Russenschuck, R. de Maria
    CERN, Geneva
  • J. Escallier, G. Ganetis, A.K. Jain, A. Marone, J.F. Muratore, R.A. Thomas, P. Wanderer
    BNL, Upton, Long Island, New York
  • M. Wilson
    Oxford Instruments, Accelerator Technology Group, Oxford, Oxon
  For the FAIR-project at GSI a model dipole was built at BNL with the nominal field of 4 T and a nominal ramp rate of 1 T/s. The magnet design was similar to the RHIC dipole with some changes for loss reduction and better cooling. The magnet was already successfully tested in a vertical cryostat with good training behaviour. Cryogenic losses were measured and first results of field harmonics were published. However, for a better understanding of the cooling process quench currents at several ramp rates were investigated. Detailed measurements of the field harmonics at different ramp rates and at several cycles were performed. To separate the effects of the coil and the iron yoke the magnet was disassembled and tested as collared coil only. Recent test results will be presented.  
TOAA010 Serpentine Coil Topology for BNL Direct Wind Superconducting Magnets quadrupole, octupole, 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.

TPAP012 Luminosity Limit from Bound-Free Pair Production in the LHC ion, simulation, luminosity, proton 1306
  • J.M. Jowett, R. Bruce, S.S. Gilardoni
    CERN, Geneva
  The luminosity of the LHC as a lead-ion collider is known to be limited by the large cross-sections for electromagnetic processes in ultra-peripheral collisions. In particular, the process of bound-free e-e+ pair production creates secondary beams of Pb81+ ions emerging from the collision points and impinging on the vacuum envelope inside superconducting magnets. New Monte-Carlo simulations, exploiting recent implementations of the physics of ion interactions with matter, are helping us to quantify the relationships among luminosity, energy deposition in the magnet coils and signals on beam loss monitors with a view to predicting and alleviating the quench limit on luminosity.  
TPAP019 Aperture Studies of the SPS to LHC Transfer Lines optics, simulation, injection, alignment 1664
  • B. Goddard, V. Kain, J. Wenninger
    CERN, Geneva
  • R. Schmid
    Bowdoin College, Brunswick, Maine
  The SPS to LHC transfer lines TI 2 and TI 8 are each several km in length and use magnets with small apertures. An aperture model for the lines has been developed in MAD-X format, with a full description of all installed vacuum elements and the possibility to interpolate at any length interval. This model has been used with tolerances and errors to simulate the expected line aperture available for the beam. The model features and simulation results are presented, with derived aperture limits. The results from aperture measurements made during the TI 8 line beam commissioning in 2004 are presented and compared to the expectations.  
TPAP024 Decoupling Schemes for the Tevatron in the Presence of Skew Quadrupole Fields lattice, quadrupole, sextupole, optics 1850
  • C. Johnstone, P. Snopok
    Fermilab, Batavia, Illinois
  • M. Berz
    MSU, East Lansing, Michigan
  Funding: Work is supported by the U.S. Department of Energy under contract no DE-AC02-76CH03000.

With increasing demands for luminosity, optimal performance must be extracted from the existing Tevatron optics. We have, therefore, initiated a high-order dynamical study of the Tevatron to assess the performance, functionality and potential of the baseline lattice. This work describes the nonlinear or high-order performance of the Tevatron lattice with emphasis on the coupled and increased nonlinear behavior introduced by the significant skew quadrupole error in combination with conventional sextupole correction, a behavior still clearly evident after optimal tuning of available skew quadrupole circuits. An optimization study is then performed using different skew quadrupole families, and, importantly, local and global correction of the linear skew terms in maps generated by the code, COSY. A correction scheme, with two families locally correcting each arc and eight independent correctors outside the arc for global correction is shown to be optimal and dramatically improve the linear performance of the baseline Tevatron lattice.

TPAP027 Deterioration of the Skew Quadrupole Moment in Tevatron Dipoles Over Time quadrupole, coupling, alignment, monitoring 1967
  • M.J. Syphers, D.J. Harding
    Fermilab, Batavia, Illinois
  Funding: United States Department of Energy under Contract No. DE-AC02-76CH03000.

During the 20 years since it was first commissioned, the Fermilab Tevatron has developed strong coupling between the two transverse degrees of freedom. A circuit of skew quadrupole magnets is used to correct for coupling and, though capable, its required strength has increased since 1983 by more than an order of magnitude. In more recent years changes to the Tevatron for colliding beams operation have altered the skew quadrupole corrector distribution and strong local coupling become evident, often encumbering routine operation during the present physics run. Detailed magnet measurements were performed on each individual magnet during construction, and in early 2003 it was realized that measurements could be performed on the magnets in situ which could determine coil movements within the iron yoke since the early 1980's. It was discovered that the superconducting coils had become vertically displaced relative to their yokes since their construction. The ensuing systematic skew quadrupole field introduced by this displacement accounts for the required corrector settings and observed beam behavior. An historical account of the events leading to this discovery and progress toward its remedy are presented.

TPAP028 Observations of Strong Transverse Coupling in the Tevatron quadrupole, coupling, betatron, collider 2029
  • M.J. Syphers, G. Annala, D.A. Edwards, N.M. Gelfand, J.A. Johnstone, M.A. Martens, T. Sen
    Fermilab, Batavia, Illinois
  Funding: United States Department of Energy under Contract No. DE-AC02-76CH03000.

During the beginning of Run II of the Tevatron Collider it became apparent that a large skew quadrupole source, or sources, had developed in the superconducting synchrotron. Efforts to locate the current source of coupling were undertaken, with the eventual discovery that the main magnets had developed a systematic skew quadrupole moment over their lifetime. Over the past year, the magnets have been altered in place in an attempt to restore the systematic skew quadrupole moment to zero. Beam observations and their interpretations are presented, and remedial measures are discussed.

TPAP029 Measurements of Field Decay and Snapback Effect on Tevatron Dipole and Quadrupole Magnets injection, sextupole, quadrupole, octupole 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.  
TPAP030 Tevatron Alignment Issues 2003-2004 quadrupole, alignment, closed-orbit, laser 2146
  • J.T. Volk, J. Annala, L. Elementi, N.M. Gelfand, K. Gollwitzer, J.A. Greenwood, M.A. Martens, C.D. Moore, A. Nobrega, A.D. Russell, T. Sager, V.D. Shiltsev, R. Stefanski, M.J. Syphers, G. Wojcik
    Fermilab, Batavia, Illinois
  Funding: U.S. Department of Energy under contract No. DE-AC02-76CH03000.

It was observed during the early part of Run II that dipole corrector currents in the Tevatron were changing over time. Measurement of the roll for dipoles and quadrupoles confirmed that there was a slow and systematic movement of the magnets from their ideal position. A simple system using a digital protractor and laptop computer was developed to allow roll measurements of all dipoles and quadrupoles. These measurements showed that many magnets in the Tevatron had rolled more than 1 milli-radian. To aid in magnet alignment a new survey network was built in the Tevatron tunnel. This network is based on the use of free centering laser tracker. During the measurement of the network coordinates for all dipole, quadrupole and corrector magnets were obtained. This paper discusses roll measurement techniques and data, the old and new Tevatron alignment network.

TPAP046 Towards an Optimization of the LHC Intersection Region using New Magnet Technology quadrupole, insertion, radiation, lattice 2920
  • P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, Texas
  • J.-P. Koutchouk
    CERN, Geneva
  An optimized design of the intersection region of LHC is presented. The starting point of the design is to move the quadrupole triplet to a minimum distance from the intersect – 12 m. The innermost quadrupole must accommodate substantial heat load from particles, and is designed using a structured cable that incorporates internal refrigeration with supercritical helium. Using the reduced aperture required by this closer spacing, Nb3Sn quadrupoles have been designed with gradients of 350-400 T/m for the triplet. The separation dipole utilizes a levitated-pole design that mitigates the extreme heat and radiation challenges for that application. The above technical elements have been incorporated into an optimized insertion design that minimizes ?* while significantly reducing sensitivities to errors in multipoles and alignment. The additional space that is opened in the lattice can be used to fully localize the optical design of the insertion so that it does not require corrections through the neighboring arcs.  
TPAP047 Killing the Electron Cloud Effect in the LHC Arcs electron, vacuum, proton, emittance 2971
  • P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, Texas
  A getter/electrode assembly has been devised to suppress the regeneration mechanism of the electron cloud effect in the arc dipoles of LHC. The assembly consists of a copper foil electrode, supported through an insulating layer on a stainless steel skid, which would rest upon the flat bottom of the beam screen. The electrode is coated with NEG to provide effective pumping of all non-inert gases from the vacuum. Pumping should be enhanced by electron bombardment. By biasing the electrode ~+100 V secondary electrons produced on the surface would be fully re-absorbed, killing the regeneration mechanism. The NEG surface can be regenerated by passing a current through the electrode to heat it to ~240 C. The heat transfer (radiant + conductive) to the beam screen during regeneration is estimated ~10 W/m, within limits to maintain the beam screen at nominal 20 K temperature during regeneration. The entire assembly has been designed so that installation does not require modification of any hardware currently being built for the LHC arcs. The electrode assembly would occupy 1 mm in the vertical aperture of the beam screen.  
TPAP053 IR Optics Measurement with Linear Coupling's Action-Angle Parameterization coupling, optics, background, heavy-ion 3218
  • Y. Luo, M. Bai, F.C. Pilat, T. Satogata, D. Trbojevic
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886.

The interaction region (IP) optics are measured with the two DX/BPMs close to the IPs at the Relativistic Heavy Ion Collider (RHIC). The beta functions at IP are measured with the two eigenmodes' phase advances between the two BPMs. And the beta waists are also determined through the beta functions at the two BPMs. The coupling parameters at the IPs are also given through the linear coupling's action-angle parameterization. All the experimental data are taken during the driving oscillations with the AC dipole. The methods to do these measurements are discussed. And the measurement results during the beta* squeezings are also presented.

TPAT018 Stability of Barrier Buckets with Short or Zero Barrier Separations resonance, synchrotron, quadrupole, beam-losses 1589
  • K.Y. Ng
    Fermilab, Batavia, Illinois
  A barrier bucket with small separation between the rf barriers (relative to the barrier widths) or even zero separation has its synchrotron tune decreasing rather slowly towards the boundary of the bucket. As a result, large area at the bucket edges can become unstable under the modulation of rf voltage and rf phase. Application is made to those barrier buckets used in the process of momentum mining on the issues of bunch-distribution distortion and particle loss.  
TPAT022 Future Plans for the Small Isochronous Ring space-charge, quadrupole, focusing, betatron 1778
  • E.P. Pozdeyev
    Jefferson Lab, Newport News, Virginia
  • F. Marti, R.C. York
    NSCL, East Lansing, Michigan
  • J.A. Rodriguez
    CERN, Geneva
  Funding: Work supported by NSF Grant #PHY-0110253 and DOE Contract DE-AC05-84ER40150.

The Small Isochronous Ring has been operational at Michigan State University since December 2003. It is used for experimental studies of the beam dynamics in high-intensity isochronous cyclotrons and synchrotrons at the transition energy. The operational experience with SIR has proven that the ring can be successfully used to study space charge effects in accelerators. The low velocity of beam particles in the ring allowed us to achieve a high accuracy of longitudinal profile measurements that is difficult to achieve in full-size accelerators. The experimental data obtained in the ring was used for validation of multi-particle, space-charge codes CYCO and WARP3D. Inspired by the solid performance of SIR in the isochronous regime, we consider options for expanding the scope of the beam physics studied in the ring. In this paper, we outline possible future experiments and discuss required modifications of the ring optics and hardware.

TPAT027 Measurement of Transverse Echoes in RHIC quadrupole, lattice, scattering, octupole 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.

TPAT078 Coherent Beam-Beam Modes in the CERN Large Hadron Collider (LHC) for Multiple Bunches, Different Collisions Schemes and Machine Symmetries simulation, damping, coupling, emittance 4030
  • T. Pieloni, W. Herr
    CERN, Geneva
  In the LHC almost 3000 bunches in each beam will collide near several experimental regions and experience head-on as well as long range beam-beam interactions. In addition to single bunch phenomena, coherent bunch oscillations can be excited. Due to the irregular filling pattern and the unsymmetric collision scheme, a large number of possible modes must be expected, with possible consequences for beam measurements. To study these effects, a simulation program was developped which allows to evaluate the interaction of many bunches. It is flexible enough to easily implement any possible bunch configuration and collision schedule and also to study the effect of machine imperfections such as optical asymmetries. First results will be presented and future developments are discussed.  
TPPE047 Fabrication and Measurement of Low Work Function Cesiated Dispenser Photocathodes cathode, electron, laser, photon 2953
  • N.A. Moody, D.W. Feldman, P.G. O'Shea
    IREAP, College Park, Maryland
  • K. Jensen
    NRL, Washington, DC
  Funding: We gratefully acknowledge our funding agencies, the Joint Technology Office and the Office of Naval Research for their support.

Photoinjector performance is a limiting factor in the continued development of high powered FELs and electron beam-based accelerators. Presently available photocathodes are plagued with limited efficiency and short lifetime in an RF-gun environment, due to contamination or evaporation of a photosensitive surface layer. An ideal photocathode should have high efficiency at long wavelengths, long lifetime in practical vacuum environments, and prompt emission. Cathodes with high efficiency typically have limited lifetime, and vice versa, and the needs of the photocathode are generally at odds with those of the drive laser. A potential solution is the low work function dispenser cathode, where lifetime issues are overcome by periodic in situ regeneration that restores the photosensitive surface layer, analogous to those used in the microwave power tube industry. This work reports on the fabrication techniques and performance of cesiated metal photocathodes and cesiated dispenser cathodes, with a focus on understanding and improving quantum efficiency and lifetime, and analyzing issues of emission uniformity. The efficiency versus coverage behavior of cesiated metals is discussed and closely matches that predicted by recent theory.*

*K. L. Jensen, et al., "Photoemission from Low Work Function Coated Metal Surfaces: A Comparison of Theory to Experiment" (this conference).

TPPE058 Dual Feed RF Gun Design for the LCLS gun, coupling, quadrupole, laser 3432
  • L. Xiao, R.F. Boyce, D. Dowell, Z. Li, C. Limborg-Deprey, J.F. Schmerge
    SLAC, Menlo Park, California
  Funding: Work supported by the U.S. DOE under contract DE-AC03-76SF00515.

In order to remove the dipole field introduced by the coupler in existing S-band BNL/SLAC/UCLA 1.6 cell rf gun, a dual feed design for the LCLS RF gun is proposed together with several significant changes. The improvements include adopting Z-coupling instead of ?-coupling for easier machining and reducing heating, increasing the 0-and ?-mode separation from 3.4 to 15 MHz to reduce the amplitude of the 0 mode, incorporating race-track cavity shape to minimize the quadruple fields, increased cooling for operation at 120Hz and other small changes to improve performance and diagnostic capabilities. The new design has been modeled with the parallel finite element eigenmode solver Omega3P to provide the desired RF parameters and to generate the gun cavity dimensions needed for fabrication.

TPPP031 A Proposal for a New HOM Absorber in a Straight Section of the PEP-II Low Energy Ring impedance, quadrupole, damping, scattering 2173
  • S.P. Weathersby, M. Kosovsky, N. Kurita, A. Novokhatski, J. Seeman
    SLAC, Menlo Park, California
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC03-76SF00515.

Attainment of high luminosity in storage ring colliders necessitates increasing stored currents and reducing bunch lengths. Consequently, intense beam fields will scatter more power into higher order modes from beam line sources such as collimators, masks and tapers. This power penetrates into sensitive components such as a bellows, causing undesirable heating and limits machine performance. To overcome this limitation we propose incorporating ceramic absorbers in the vicinity of the bellows to damp beam induced modes while preserving a matched impedance to the beam. This is accomplished with an absorber configuration which damps TE dipole and quadrupole traveling waves while preserving TM monopole propagation. A scattering parameter analysis is presented utilizing properties of commercial grade ceramics and indicates a feasible solution.

TPPP033 Cavity Alignment Using Beam Induced Higher Order Modes Signals in the TTF Linac alignment, single-bunch, linac, higher-order-mode 2284
  • M.C. Ross, J.C. Frisch, K.E. Hacker, R.M. Jones, D.J. McCormick, C.L. O'Connell, T.J. Smith
    SLAC, Menlo Park, California
  • N. Baboi, M.W. Wendt
    DESY, Hamburg
  • O. Napoly, R. Paparella
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  Funding: DE-AC02-76SF00515.

Each nine cell superconducting accelerator cavity in the TESLA Test Facility (TTF) at DESY* has two higher order mode (HOM) couplers that efficiently remove the HOM power.** They can also provide useful diagnostic signals. The most interesting modes are in the first 2 cavity dipole passbands. They are easy to identify and their amplitude depends linearly on the beam offset from the cavity axis making them excellent beam position monitors (BPM). By steering the beam through an eight-cavity cryomodule, we can use the HOM signals to estimate internal residual alignment errors and minimize wakefield related beam emittance growth. We built and commissioned a four channel heterodyne receiver and time-domain based waveform recorder system that captures information from each mode in these two bands on each beam pulse. In this paper we present an experimental study of the single-bunch generated HOM signals at the TTF linac including estimates of cavity alignment precision and HOM BPM resolution.

*P. Piot, DESY-TESLA-FEL-2002-08. **R. Brinkmann et al. (eds.), DESY-2001-011.

TPPP039 Geant Simulation of Six-Dimensional Cooling of a Muon Beams in a Ring Coolers simulation, emittance, focusing, beam-losses 2580
  • A. Klier, G.G. Hanson
    UCR, Riverside, California
  The reduction of the phase-space volume of the beam (cooling) is essential for both muon colliders and neutrino factories. In a muon collider, in particular, the six-dimensional (6D) emittance must be reduced by six orders of magnitude. Cooling the beam in all phase space dimensions can be done through emittance exchange, where the beam loses energy passing through wedge-shaped absorbers in a dispersive magnetic field, designed in a way that fast muons go through more absorber material than slow ones and lose more energy. The longitudinal momentum is then regained using RF cavities. We simulate ring coolers, in which the beam undergoes 6-dimensional cooling through emittance exchange while rotating several times in the ring. The simulation software is a Geant3-based package, specially designed this purpose, with changing electric fields in RF cavities treated correctly. Magnetic fields are read from external maps. Some ring cooler designs and cooling simulation results are presented.  
TPPP040 Front-End Design Studies for a Muon Collider collider, target, simulation, proton 2610
  • R.C. Fernow, J.C. Gallardo
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. Department of Energy.

Using muons instead of electrons is a promising approach to designing a lepton-lepton collider with energies beyond that available at the proposed ILC. At this time a self-consistent design of a high-luminosity muon collider has not been completed. However, a lot of progress has been made in simulating cooling and parts of other systems that could play a role in an eventual collider design. In this paper we look at front-end system designs that begin with a single pion bunch produced from a high power mercury target. We present ICOOL simulation results for phase rotation, charge separation, and pre-cooling of the muon beams. A design is presented for a single-frequency phase rotation system that can transmit 0.47 muons per incident proton on the target. A bent solenoid can be used for high-efficiency separation of the positive and negative muon beams.

TPPP048 A Compact 6D Muon Cooling Ring emittance, closed-orbit, simulation, lattice 3025
  • H.G. Kirk, S.A. Kahn
    BNL, Upton, Long Island, New York
  • D. Cline, A.A. Garren
    UCLA, Los Angeles, California
  • F.E. Mills
    Fermilab, Batavia, Illinois
  Funding: U.S. Department of Energy.

We discuss a conceptual design for a compact muon cooling system based on a weak-focusing ring loaded with high-pressure Hydrogen gas. We demonstrate that such a ring will be capable of cooling a circulating muon beam in each of the three spatial dimensions so that 6d cooling of the muon beam phase space is achieved.

TPPP050 Novel Muon Cooling Channels Using Hydrogen Refrigeration and High Temperature Superconductor beam-cooling, simulation, quadrupole, superconducting-magnet 3126
  • L. DelFrate, E. Barzi, D. Turrioni
    Fermilab, Batavia, Illinois
  • M. Alsharo'a, R.P. Johnson, M. Kuchnir
    Muons, Inc, Batavia
  Funding: This work was supported in part by DOE STTR grant DE-FG02-04ER86191.

Ionization cooling, a method for shrinking the size of a muon beam, requires a low Z energy absorber, high-field magnets, and high gradient RF. It is proposed to use one gaseous hydrogen system to provide ionization energy loss for muon beam cooling, breakdown suppression for pressurized high-gradient RF cavities, and refrigeration for superconducting magnets and cold RF cavities. We report progress on the design of a cryostat and refrigeration system that circulates hydrogen through magnetic coils, RF cavities, and the absorber volume to achieve a safe, robust means to enable exceptionally bright muon beams. We find that the design can be greatly simplified if a high temperature superconductor can be used that has the capability to carry adequate current in fields above 10 T at a temperature above 33 K, the critical temperature of hydrogen.

TPPP056 MANX, A 6-D Muon Cooling Demonstration Experiment emittance, quadrupole, collider, factory 3331
  • T.J. Roberts, M. Alsharo'a, P.M. Hanlet, R.P. Johnson, M. Kuchnir, K. Paul
    Muons, Inc, Batavia
  • C.M. Ankenbrandt, A. Moretti, M. Popovic, V. Yarba
    Fermilab, Batavia, Illinois
  • D.M. Kaplan, K. Yonehara
    Illinois Institute of Technology, Chicago, Illinois
  Funding: This work was supported in part by DOE SBIR grant DE-FG02-04ER84015.

Most ionization cooling schemes now under consideration are based on using many large flasks of liquid hydrogen energy absorber. One important example is the proposed Muon Ionization Cooling Experiment (MICE), which has recently been approved to run at the Rutherford Appleton Laboratory (RAL). In the work reported here, a potential muon cooling demonstration experiment based on a continuous liquid energy absorber in a helical cooling channel (HCC) is discussed. The original HCC used a gaseous energy absorber for the engineering advantage of combining the energy absorption and RF energy regeneration in hydrogen-filled RF cavities. In the Muon And Neutrino eXperiment (MANX) that is proposed here, a liquid-filled HCC is used without RF energy regeneration to achieve the largest possible cooling rate in six dimensions. In this case, the magnetic fields of the HCC must diminish as the muons lose momentum as they pass through the liquid energy absorber. The length of the MANX device is determined by the maximum momentum of the muon test beam and the maximum practical field that can be sustained at the magnet coils. We have studied a 3 meter-long HCC example that could be inserted between the MICE spectrometers at RAL.

TPPT010 HOM Damping of ARES Cavity System for SuperKEKB coupling, klystron, damping, luminosity 1186
  • T. Kageyama, T. Abe, H. Sakai, Y. Takeuchi
    KEK, Ibaraki
  The ARES cavity scheme is a decisive edge for KEKB to stably accelerate high-current electron and positron beams. The RF structure is a coupled-cavity system where a HOM-damped accelerating cavity is coupled with a large cylindrical energy storage cavity via a coupling cavity between. The HOM-damped structure is designed to be smoothly embedded into the whole coupled-cavity scheme without any structural or electromagnetic incompatibility. Currently, the total HOM power dissipated in the RF absorbers per cavity is about 5 kW according to calorimetric measurements in the KEKB LER with a beam current of 1.6 A. On the other hand, for SuperKEKB aiming at luminosity frontiers over 1035 cm-2 s-1, the total HOM power per cavity is estimated about 100 kW for the LER with the design beam current of 9.4 A. In this article, a new HOM-damped structure of the ARES cavity system designed for the SuperKEKB LER is reported together with the recent activities and future plans for upgrading the HOM absorbers.  
TPPT020 30 GHz Power Production in CTF3 linac, beam-losses, vacuum, beam-loading 1695
  • W. Wuensch, C. Achard, H.-H. Braun, G. Carron, R. Corsini, A. Grudiev, S.T. Heikkinen, D. Schulte, J.P.H. Sladen, I. Syratchev, F. Tecker, I. Wilson
    CERN, Geneva
  One of the major objectives of CTF3 (CLIC Test Facility) is the production of 30 GHz power for the high-gradient testing of CLIC accelerating structures. To this end a dedicated beam line, power generating structure and power transfer line have been designed, installed and commissioned. 52 MW of 30 GHz power with a pulse length of 74 ns and a repetition rate of 16 Hz were delivered to the high-gradient test area. This will allow operation of test accelerating structures in the coming run of CTF3 up to the nominal CLIC accelerating gradient of 150 MV/m and beyond the nominal pulse length. The system is described and the performances of the CTF3 linac, beam line and the rf components are reviewed.  
TPPT031 Coupler Design for the LCLS Injector S-Band Structures quadrupole, emittance, multipole, linac 2176
  • Z. Li, L.D. Bentson, J. Chan, D. Dowell, C. Limborg-Deprey, J.F. Schmerge, D.C. Schultz, L. Xiao
    SLAC, Menlo Park, California
  Funding: Work supported by the U.S. DOE Contract No. DE-AC03-76SF00515.

The LCLS injector is required to provide a 1-nC, 10-ps bunch with a normalized rms transverse projected emittance of less than 1.0-μm. The LCLS beam is generated and accelerated in a 1.6-cell S-band RF gun to 6-MeV followed by two SLAC 3-m S-band accelerator structures to further accelerate the beam to 135 MeV to move it out of the space-charge dominated regime. In the SLAC S-band structures, the RF power feed is through a single coupling-hole (single-feed coupler) which results in a field asymmetry. The time dependent multipole fields in the coupler induce a transverse kick along the bunch and cause the emittance to increase above the LCLS specification. To meet the stringent emittance requirements for the injector, the single-feed couplers will be replaced by a dual-feed racetrack design to minimize the multipole field effects. We will present detailed studies of the multipole fields in the S-band coupler and the improvements with the dual-feed racktrack design using the parallel finite element eigenmode solver Omega3P.

TPPT040 X-Band Dipole Mode Deflecting Cavity for the UCLA Neptune Beamline diagnostics, resonance, vacuum, simulation 2627
  • R.J. England, B. O'Shea, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • D. Alesini
    INFN/LNF, Frascati (Roma)
  Funding: This work was funded by the Department of Energy under Grant No. DE-FG03-92ER40693.

We report progress on the design and construction of a nine-cell dipole (TM 110 mode) cavity for use as a temporal diagnostic of the 14 MeV 300 pC electron bunches generated at the UCLA Neptune Laboratory linear accelerator, with an anticipated temporal resolution of 150 fs at a peak input power of 50 kW. The cavity is a center-fed standing-wave pi-mode structure, operating at 9.6 GHz, and incorporating a knife-edge and gasket assembly which minimizes the need for brazing or welding. Results of initial RF tests are discussed and compared with simulation results obtained using the commercial code HFSS.

TPPT044 Beam Position Monitoring Using the HOM-Signals from a Damped and Detuned Accelerating Structure linac, linear-collider, collider, alignment 2804
  • S. Doebert, C. Adolphsen, R.M. Jones, J.R. Lewandowski, Z. Li, M.T.F. Pivi, J.W. Wang
    SLAC, Menlo Park, California
  • T. Higo
    KEK, Ibaraki
  Funding: Work Supported by DOE Contract DE-AC02-76F00515.

The Next Linear Collider (NLC) and Global Linear Collider (GLC) designs require precision beam-to-accelerator-structure alignment to reduce the effect of short range wakefields. For this purpose, the HOM signals from the structure dipole mode damping ports would be used to determine the beam position in the structure, and then the structures would be moved remotely to center them about the beam (a 5 micron rms alignment is required). In 2000, a test of a 1.8 m prototype structure in the ASSET facility at SLAC achieved 11 micron rms centering accuracy, which was limited by systematic effects caused by beam jitter. This year, such measurements were repeated for a pair of shorter structures (60 cm) that were developed to improve high gradient performance. In addition, the beam position resolution was determined by measuring simultaneously three signal frequencies (14.3, 15, 15.7 GHz) corresponding to modes localized at the beginning, the middle and the end of the structures. In this paper, we present results from the beam centering and position resolution measurements.

TPPT050 Rod-Loaded and PBG Multi-Beam Klystron Cavities coupling, klystron, lattice, cathode 3094
  • A. Smirnov, D. Yu
    DULY Research Inc., Rancho Palos Verdes, California
  Funding: Work supported by DOE SBIR Grant No. DE-FG02-03ER83845.

Performance of PBG-like structures was studied for multi-defect and single-defect metal cavities. Conceptual designs of a 6-beam, X-band, multi-beam klystron (MBK) demonstrate feasibility of high power generation with efficiency ~63% in a compact structure. Sheet-beam and annular-beam rod-loaded configurations were also investigated.

TPPT056 Design of a Low Loss SRF Cavity for the ILC damping, linac, linear-collider, collider 3342
  • J.S. Sekutowicz
    DESY, Hamburg
  • L. Ge, K. Ko, L. Lee, Z. Li, C.-K. Ng, G.L. Schussman, L. Xiao
    SLAC, Menlo Park, California
  • I.G. Gonin, T.K. Khabiboulline, N. Solyak
    Fermilab, Batavia, Illinois
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • Y. Morozumi, K. Saito
    KEK, Ibaraki
  An international team comprising DESY, KEK, JLAB, FNAL and SLAC is collaborating on the design, fabrication and test of a low loss, 1.3 GHz 9-cell SRF structure as a potential improvement for the ILC main linac. The advantages of this structure over the TTF structure include lower cryogenic loss, shorter rise time, and less stored energy. Among the issues to be addressed in this design are HOM damping, Lorentz force detuning and multipacting. We will report on HOM damping calculations using the parallel finite element eigenmode solver Omega3P and the progress made towards an optimized design. Studies on multipacting and estimates of the Lorentz force detuning will also be presented.  
TPPT063 Higher-Order-Mode Damping of L-Band Superconducting Cavity using a Radial-Line HOM Damper damping, simulation, linac, quadrupole 3606
  • K. Umemori, M. Izawa, K. Saito, S. Sakanaka
    KEK, Ibaraki
  For the energy recovery linacs, strong damping of higher-order-modes (HOMs) is indispensable to avoid beam breakup instabilities. We studied a new HOM damping scheme using a radial-line HOM damper with a choke structure. Both models of the radial-line damper and the TESLA-type 9-cell cavity were prepared and the HOM characteristics of this scheme were experimentally investigated. Measurement results showed a promising performance of the radial-line HOM damper.  
TPPT081 Fabrication and Testing of the SRF Cavities for the CEBAF 12 GeV Upgrade Prototype Cryomodule Renascence damping, coupling, simulation, impedance 4081
  • C.E. Reece, E. Daly, S. Manning, R. Manus, S. Morgan, J.P. Ozelis, L. Turlington
    Jefferson Lab, Newport News, Virginia
  Funding: This manuscript has been authorized by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy.

Twelve seven-cell niobium cavities for the CEBAF 12 GeV upgrade prototype cryomodule Renascence have been fabricated at JLab and tested individually. This set includes four of the "Low Loss" (LL) design and eight of the "High Gradient" (HG) design. The fabrication strategy was an efficient mix of batch job-shop component machining and in-house EBW, chemistry, and final-step machining to meet mechanical tolerances. Process highlights will be presented. The cavities have been tested at 2.07 K, the intended CEBAF operating temperature. Performance exceeded the tentative design requirement of 19.2 MV/m cw with less than 31 W dynamic heat dissipation. These results, as well as the HOM damping performance will be presented.

TOPA005 Left-Handed Metamaterials Studies and their Application to Accelerator Physics radiation, electron, plasma, diagnostics 458
  • S.P. Antipov, W. Liu, J.G. Power
    ANL, Argonne, Illinois
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois
  Funding: DOE grant NSF grant

Recently, there has been a growing interest in applying artificial materials, known as Left-Handed Metamaterials (LHM), to accelerator physics. These materials have both negative permittivity and permeability and therefore possess several unusual properties: the index of refraction is negative and the direction of the group velocity is antiparallel to the direction of the phase velocity (along k). These properties lead to a reverse Cherenkov effect, which has potential beam diagnostic applications, in addition to accelerator applications. Several LHM devices with different configurations are being experimentally and theoretically studied at Argonne. In this paper, we describe permittivity and permeability retrieval techniques that we have developed and applied to these devices. We have also investigated the possibility of building a Cherenkov detector based on LHM and propose an experiment to observe the reverse radiation generated by an electron beam passing through a LHM. The potential advantage of a LHM detector is that the radiation in this case is emitted in the direction reversed to the direction of the beam, so it could be easier to get a clean measurement.

TOPD003 Cooler Storage Ring at China Institute of Modern Physics ion, heavy-ion, injection, lattice 271
  • J.W. Xia
    IMP, Lanzhou
  • B.W. Wei, W.L. Zhan
    IHEP Beijing, Beijing
  CSR, a new ion cooler-storage-ring project in China IMP, is a double ring system, and consists of a main ring (CSRm) and an experimental ring (CSRe). The two existing cyclotrons SFC (K=69) and SSC (K=450) of the Heavy Ion Research Facility in Lanzhou (HIRFL) will be used as its injector system. The heavy ion beams with the energy range of 7–30 MeV/nucleus from the HIRFL will be accumulated, cooled and accelerated to the higher energy range of 100–500 MeV/ nucleus in CSRm, and then extracted fast to produce radioactive ion beams or highly charged heavy ions. Those secondary beams will be accepted and stored or decelerated by CSRe for many internal-target experiments or high precision spectroscopy with beam cooling. On the other hand, the beams with the energy range of 100–1000MeV/ nucleus will also be extracted from CSRm by using slow extraction or fast extraction for many external-target experiments. CSR project was started in the end of 1999 and will be finished in 2006. In this paper the outline and the activities of the project will be described.  
WPAE027 Magnetic Shielding of an Electron Beamline in a Hadron Accelerator Enclosure electron, shielding, antiproton, quadrupole 1997
  • T.K. Kroc, C.W. Schmidt, A.V. Shemyakin
    Fermilab, Batavia, Illinois
  Funding: *Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

The Fermilab Electron Cooling Project requires the operation of a 4.35 MeV electron beam in the same enclosure that houses the 120 – 150 GeV Main Injector. Effective shielding of the magnetic fields from the ramped electrical buses and local static fields is necessary to maintain the high beam quality and recirculation efficiency required by the electron cooling system. This paper discusses the operational tolerances and the design of the beamline shielding, bus design, and bus shielding as well as experimental results from the prototype and final installation.

WPAE031 Mechanical Design of a Heavy Ion Beam Dump for the RIA Fragmentation Line radiation, ion, heavy-ion, vacuum 2185
  • W. Stein, L. Ahle
    LLNL, Livermore, California
  • D.L. Conner
    ORNL, Oak Ridge, Tennessee
  The RIA fragmentation line requires a beam stop for the primary beam downstream of the first dipole magnet. The beam may consist of U, Ca, Sn, Kr, or O ions. with a variety of power densities. The configuration with highest power density is for the U beam, with a spot size of 3 cm x 3 cm and a total power of up to 300 kW. The mechanical design of the dump that meets these criteria consists of a 50 cm diameter aluminum wheel with water coolant channels. A hollow drive shaft supplies the coolant water and connects the wheel to an electrical motor located in an air space in the floor above the dump. The beam strikes the wheel along the outer perimeter and passes through a thin window of aluminum where 10% of its power is absorbed and the remainder of the beam is absorbed in flowing water behind the window. Rotation of the wheel at 400 RPM results in maximum aluminum temperatures below 100 C and acceptably low thermal stresses of 5 ksi. Rotating the wheel also results in low radiation damage levels by spreading the damage out over the whole perimeter of the wheel. For some of the other beams, a stationary dump consisting of a thin aluminum window with water acting as a coolant and absorber appears to be feasible.  
WPAE035 SNS Ring Injection Stripped Electron Collection: Design Analysis and Technical Issues electron, SNS, injection, beam-losses 2384
  • Y.Y. Lee, G.J. Mahler, W. Meng, D. Raparia, L. Wang, J. Wei
    BNL, Upton, Long Island, New York
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

This paper describes the simulation studies on the motions of stripped electrons generated in the injection section of the Spallation Neutron Source (SNS) accumulator ring and the effective collection mechanism. Such studies are important for high intensity machines, in order to reduce beam loss and protect other components in the vicinity. The magnetic field is applied to guide electrons to a collector, which is located at the bottom of the beam chamber. Part of the study results with and without considering the interactions between electrons and materials are presented and discussed. The final engineering design of the electron collector (catcher) is also presented and described.

WPAE043 Alignment of the Booster Injector for the Duke Free Electron Laser Storage Ring alignment, booster, laser, storage-ring 2786
  • M. Emamian, M.D. Busch, S. Mikhailov
    DU/FEL, Durham, North Carolina
  • N. Gavrilov
    BINP SB RAS, Novosibirsk
  Funding: This work is supported by U.S. Department of Energy grant DE-FG02-01ER41175 and by U.S. AFOSR MFEL grant F49620-001-0370.

This paper presents the methodology and initial results for mechanical alignment of the booster synchrotron for the Duke FEL storage ring. The booster is a compact design and requires special considerations for alignment. The magnetic and vacuum elements of the arcs have been designed for alignment by a laser tracker system. A parametric 3D design package has been used to determine target coordinates. These target coordinates evolve from design goals to physically verified dimensions by modifying the parametric model to match mechanical measurement data after fabrication. By utilizing the functionality of the laser tracker system and a parametric 3D modeler, a direct and efficient measurement and alignment technique has been developed for a complex geometry.

WPAE071 Power Supply for Magnet of Compact Proton and/or Heavy Ion Synchrotron for Radiotherapy power-supply, injection, synchrotron, acceleration 3859
  • S. Yamanaka
    NIRS, Chiba-shi
  • K. Egawa, K. Endo, Z. Fang
    KEK, Ibaraki
  A resonant type pulse power supply, for an application to a compact proton and/or heavy ion synchrotron with a several Hz repetition rate, is attractive from the view point of attaining an average beam current that is enough for the radiation therapy. Maximum ampere-turn of the dipole magnet is as large as 200 kAT to make the bending radius as small as possible. Pulse current is generated by discharging the stored energy in a capacitor bank through a pulse transformer. Moreover, the auxiliary power supply for the dipole magnets which adds the flat magnetic field (10-20μs) for the multi-turn beam-injection is being developed. The power supply for the quadrupole magnets is the high switching frequency (20 kHz × 5) switching-mode Power Supply for the adjusting tune and the tracking between the quadrupole and the dipole fields.Detailed analyses on these pulse power supplies will be presented.  
WPAE072 Installation and Testing of SNS Magnet Power Supplies power-supply, SNS, linac, injection 3889
  • K.R. Rust, W.E. Barnett, R.I. Cutler, J. T. Weaver
    ORNL, Oak Ridge, Tennessee
  • S. Dewan, R. Holmes, S. Wong
    IE Power Inc., Mississauga, Ontario
  • R.F. Lambiase, J. Sandberg
    BNL, Upton, Long Island, New York
  • J. Zeng
    Digital Predictive Systems Inc., Toronto
  Funding: This work was supported by SNS through UT-Batelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

This paper describes the types and quantities of magnet power supplies required for the SNS Linear Accelerator, High-Energy Beam Transport (HEBT), Ring and the Ring-Target Beam Transport (RTBT). There are over 600 magnets and more than 550 magnet power supplies. These magnet power supplies range in size from the bipolar-corrector supplies rated at 35 volts, 20 amps to the main-ring dipole supply that is rated at 440 volts, 6000 amps. The Linac power supplies have a ripple/stability specification of 1000 parts per million while the ring supplies have a specification of 100 parts per million. There are also pulsed power supplies for beam injection and beam extraction. The paper will show acceptance test results from the manufacturers as well as test results performed by the SNS magnet power supply group.

WPAT081 Ceramic Power Extractor Design at 15.6 GHz linac, single-bunch, quadrupole, beam-transport 4078
  • A. Smirnov, Y. Luo, R. Yi, D. Yu
    DULY Research Inc., Rancho Palos Verdes, California
  Funding: Work supported by DOE SBIR Grant No. DE-FG03-01ER83232.

Power extractor and coupler designs developed for an experiment planned at the 12th beam harmonic of the upgraded Advanced Wakefield Accelerator (AWA) facility is described. New features are an upstream HOM dielectric damper with additional tapering, and a single-port coupler considered in two variants. Performance analysis includes coupler geometric tolerances, overvoltage, dipole mode wake and BBU; and wakefield losses induced in the damper.

WPAT093 A Three-Cell Superconducting Deflecting Cavity Design for the ALS at LBNL impedance, simulation, damping, coupling 4287
  • J. Shi, H. Chen, S. Zheng
    TUB, Beijing
  • J.M. Byrd, D. Li
    LBNL, Berkeley, California
  Deflecting RF cavities can be used to generate sub-pico-second x-rays by creating correlations between longitudinal and transverse phase space of electron bunches in radiation devices. Up to 2-MV defecting voltage at 1.5-GHz is required for 1.9-GeV electron beam at the Advanced Light Source (ALS) at LBNL. We present a conceptual design for a 1.5-GHz three-cell superconducting RF cavity and its coupler. The cavity geometry and deflecting shunt impedance are optimized using MAFIA code. The cavity impedance from lower and higher order modes (LOM and HOM) are computed. Possible schemes for damping most harmful LOM and HOM modes are discussed and simulated.  
WOAB007 SESAME in Jordan sextupole, synchrotron, vacuum, injection 586
  • G. Vignola, A. Amro, M. Attal, F. Makahleh, M.M. Shehab, S. Varnasseri
    SESAME, Amman
  An overview of the status of SESAME is presented. SESAME (Synchrotron-light for Experimental Science and Application in the Middle East) is an Independent Intergovernmental Organization developed and officially established under the auspices of UNESCO. It involves at the present the following Member States: Bahrain, Egypt, Islamic Republic of Iran, Israel, Jordan, Pakistan, Palestinian Authority, Turkey and United Arab Emirates. Moreover the following States are Observer of SESAME Council: France, Germany, Greece, Italy, Kuwait, Russian Federation, Sweden, UK and United States of America. SESAME will become a major international research center in the Middle East, located in Allan, Jordan. The machine design is based on a 2.5 GeV 3rd generation Light Source with an emittance of 26 nm.rad and 11 straights for insertion devices. The conceptual design of the accelerator complex has been frozen and the engineering design is started. The Phase I scientific program for SESAME has also been finalized and it foresees 6 beamlines. The construction of SESAME building is in progress and the beneficial occupancy is expected by the first half of 2006. The completion of the accelerators complex construction is scheduled for the end of 2009.  
WOAC002 Chromatically Corrected Imaging Systems for Charged-Particle Radiography proton, quadrupole, sextupole, multipole 225
  • B. Blind, A.J. Jason
    LANL, Los Alamos, New Mexico
  In proton radiography, imaging with systems consisting of quadrupole magnets is an established technique for viewing the material distribution and composition of objects, either statically or during fast events such as explosions. With the most favorable magnet configuration, the –I lens, chromatic aberrations generally dominate the image blur. Image resolution can be improved, and largely decoupled from the input-beam parameters, by using a second-order achromatic bend with some additional higher-order aberration correction. The aberration-correction approach is discussed. For a given resolution, such a bend allows use of much lower-energy imaging particles than a –I lens. Each bend design represents a set of equivalent systems; an 800-MeV proton design and its equivalent 40-MeV electron system are presented. The electron system is useful for imaging small objects. Magnet errors in the achromatic bends must be tightly controlled to preserve image quality, but not beyond feasibility of present technology. System performance is verified by particle tracking. Configurations alternative to the canonical achromatic bend are also discussed.  
RPAE027 Linear Optics Measurements in the ESRF Booster booster, sextupole, injection, optics 1973
  • Y. Papaphilippou, L. Farvacque, E. Plouviez
    ESRF, Grenoble
  • A. Mostacci, A. Patriarca
    Rome University La Sapienza, Roma
  A series of experiments has been conducted in the ESRF booster in order to measure its linear optics. A steerer response matrix was developed and used to optimise the orbit correction at injection by developing a refined model. This matrix was also used to measure the beta functions along the accelerating cycle and the steerer calibration. Dispersion was also measured with classical RF scans and compared to theory. Finally, chromaticity measurements were performed for different sextupole settings enabling their calibration and optimisation.  
RPAE028 Lattice Upgrade Options for the ESRF Storage Ring emittance, lattice, optics, quadrupole 2047
  • Y. Papaphilippou, P. Elleaume, L. Farvacque, A. Ropert
    ESRF, Grenoble
  Several scenarios of lattice upgrade for the ESRF storage ring are under study. In order to minimise the cost, their design is based on the length constraints of the existing tunnel with the ID beamlines kept in place. The goal is to shrink the emittance in order to increase the undulator brilliance. The two main options are a double bend achromat structure with non-uniform field dipoles and a triple bend achromat lattice. The two scenarios are detailed and compared with respect to their linear optics solutions, correction of chromatic effects and non-linear dynamics. An attempt to reveal the horizontal effective emittance dependence on important design parameters, such as optics functions maxima, chromaticity and dynamic aperture, is also undertaken. Technological challenges concerning magnet design with small physical aperture in a reduced space are also addressed.  
RPAE029 Analytical Considerations for Reducing the Effective Emittance with Variable Dipole Field Strengths emittance, optics, betatron, damping 2086
  • Y. Papaphilippou, P. Elleaume
    ESRF, Grenoble
  The basic optics design scope in lepton rings is to match the sections in either side of the bending magnets in order to minimise the equilibrium emittance. A further important emittance reduction can be achieved by incorporating dipoles for which the deflecting field varies along the electron beam path in the magnet. The figure of merit for such lattices when used in a synchrotron light source is the minimization of the so-called effective emittance. The effective emittance is computed in the middle of the undulator straight section as the product of the rms size and divergence and therefore includes contributions from the betatron emittance and from the electron energy spread. In this paper, analytical formulas are obtained for the minimum betatron and effective emittance in arbitrary dipole fields and the associated optics function at the dipole entrance. Examples are given for specific dipole field functions and their properties with respect to the effective emittance minimisation. Finally, the effective emittance is parameterised with respect to standard cell optics properties, such as the phase advance, the maximum beta and dispersion functions and the focusing element strengths.  
RPAE030 Status of the SOLEIL Booster Synchrotron booster, power-supply, injection, quadrupole 2155
  • A. Loulergue
    SOLEIL, Gif-sur-Yvette
  Funding: SOLEIL.

SOLEIL is a 2.75 GeV third generation synchrotron radiation facility under construction near Paris. The injection system is composed of a 100 MeV electron Linac pre-accelerator followed by a full energy (2.75 GeV) booster synchrotron. The booster lattice is based on a FODO structure with missing magnet. With a circumference of 157 m and low field magnets (0.74 T), the emittance is of 150 nm.rad at 2.75 GeV. A flexible and economic ramping switched mode procedure for the main supply cycled up to 3 Hz and a 35 kW-352 MHz solid state amplifier powering the RF system are used. At present time, all the magnets, supports and vacuum have been received and tested. Half of the ring is already assembled and installation is the tunnel will begin in January 05. The pulsed elements and their pulser will be received and tested from January to April. The four main magnet power supplies will be received in February and tested in Marsh. We plan the booster commissioning with beam in May 2005.

RPAE031 Progress Report on the Construction of SOLEIL vacuum, quadrupole, sextupole, power-supply 2203
  • M.-P. Level, J.C. Besson, P. Brunelle, R. Chaput, A. Dael, J.-C. Denard, J.-M. Filhol, J.M. Godefroy, C. Herbeaux, V. Le Roux, P. Marchand, A. Nadji, L.S.N. Nadolski, R. Nagaoka, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  Funding: SOLEIL

This paper reports the progress achieved in the construction of the accelerators of SOLEIL. Started in January 2002, the construction comes near to its end and the installation of the equipment on the site has begun from September 2004 and shall be completed within one year. The progress on the LINAC and Booster are reported separately, therefore this paper will focus more particularly on the Storage Ring: Dedicated measuring benches have been built to perform the magnetic measurements on all the magnets and the results of measurements have been analysed in term of particle dynamics behaviour in order to prepare the operating point for the commissioning. The status of innovative developments engaged from the beginning as super-conducting RF cavities, NEG coated vacuum chambers and BPMs digital electronics will be described. The construction of the first 6 insertion devices is also well advanced and will be reported. Finally, the machine impedance budget was further evaluated with consequently, still some modifications to the design of some components.

RPAE032 Femtosecond Laser-Electron Interaction in a Storage Ring Studied by Terahertz Radiation electron, laser, radiation, storage-ring 2239
  • K. Holldack, S. Khan, T. Quast
    BESSY GmbH, Berlin
  • R. Mitzner
    Universität Muenster, Physikalisches Institut, Muenster
  Funding: This work was supported by the german Bundesministerium für Bildung und Forschung (BMBF).

The laser-induced energy modulation of relativistic electrons in the BESSY II storage ring was studied by temporal and spectral characterization of femtosecond far infrared (THz) pulses being emitted due to the fact that dispersive elements convert the energy modulation into a longitudinal density modulation. Bunch shapes down to 3 ps and phase noise effects as well as the length of the femtosecond density modulation and its temporal decay were measured. The THz diagnostics is crucial for the operation of the recently commissioned undulator based "femtosecond slicing" source at BESSY.

RPAE035 Orbit Stability at BESSY feedback, diagnostics, electron, insertion 2366
  • R. Müller, J. Feikes, K. Holldack, P. Kuske
    BESSY GmbH, Berlin
  Funding: Funded by the Bundesministerium für Bildung und Forschung and by the Land Berlin.

Traditionally intrinsic component stability as well as perturbation source identification and suppression (like set-up modifications or feed-forward compensations) have been the preferred methods used to guarantee beam orbit stability for user operation at BESSY. Second focus of activity is the reliability of slow drift control and the high degree of beam position reproducibility maintained under frequently changed operation conditions. Along these lines an overview of the measures taken, the available diagnostic means as well as the achievements and shortcomings of the existing slow orbit feedback is given. Diagnostic capabilities of a fast BPM read-out and data distribution system give insight into the demands on a fast orbit feedback that could provide better operation flexibility and improved performance.

RPAE040 COD Correction at the PF and PF-AR by New Orbit Feedback Scheme feedback, insertion, insertion-device, electron 2613
  • K. Harada, T. Obina
    KEK, Ibaraki
  • N. Nakamura, H. Sakai, H. Takaki
    ISSP/SRL, Chiba
  The eigen-vector method with a constraint condition is a new COD correction method that enables us to combine the local orbit correction at the insertion devices with the global COD correction by integrating the local one into the global one as the constraint condition using the Lagrange’s undetermined multiplier method. In order to achieve this method, we only use the new contrived response matrix for the global COD correction where the local correction is involved and done simultaneously. We have tested this correction scheme at the PF ring and the PF-AR. In the machine studies, the new orbit correction method is successfully demonstrated. The RMS COD of the constraint BPMs are sufficiently suppressed and, on the other hand, there is almost no large difference in the RMS COD of all the other BPMs between the new and ordinary methods.  
RPAE052 Overview of Accelerator Physics Studies and High Level Software for the Diamond Light Source booster, storage-ring, linac, collimation 3188
  • R. Bartolini, A.I. Baldwin, M. Belgroune, C. Christou, V.C. Kempson, I.P.S. Martin, J.H. Rowland, B. Singh
    Diamond, Oxfordshire
  • D.J. Holder, J.K. Jones, S.L. Smith, J.A. Varley, N.G. Wyles
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  DIAMOND is a 3 GeV synchrotron light source under construction at Rutherford Appleton Laboratory in Oxfordshire (UK). The accelerators complex consists of a 100 MeV LINAC, a full energy booster and a 3GeV storage ring with 22 straight sections available for IDs. Installation of all three accelerators has begun, and LINAC commissioning is due to start in Spring 2005. This paper will give an overview of the accelerator physics activity to produce final layouts and prepare for the commissioning of the accelerator complex. The DIAMOND facility is expected to be operational for users in 2007  
RPAE057 Dynamic Aperture Optimization for Low Emittance Light Sources lattice, sextupole, emittance, quadrupole 3378
  • S.L. Kramer, J. Bengtsson
    BNL, Upton, Long Island, New York
  Funding: Under Contract with the United States Department of Energy Contract Number DE-AC02-98CH10886.

State of the art low emittance light source lattices, require small bend angle dipole magnets and strong quadrupoles. This in turn creates large chromaticity and small value of dispersion in the lattice. To counter the high chromaticity strong sextupoles are required which limit the dynamic aperture. Traditional methods for expanding the dynamic aperture use harmonic sextupoles to counter the tune shift with amplitude. This has been successful up to now, but is non-deterministic and limited as the sextupole strength increases, driving higher order nonlinearities. We have taken a different approach that makes use of the tune flexibility of a TBA lattice to minimize the lowest order nonlinearities, freeing the harmonic sextupoles to counter the higher order nonlinearities. This procedure is being used to improve the nonlinear dynamics of the NSLS-II lattice.

RPAE059 Design of 3 GeV Booster for NSLS-II booster, injection, lattice, sextupole 3473
  • T.V. Shaftan, E.D. Johnson, J.B. Murphy, I.P. Pinayev, J. Rose, X.J. Wang
    BNL, Upton, Long Island, New York
  We present preliminary design of full energy booster for NSLS-II. In the paper we analyze single- and multi-bunch modes of the booster operations. The booster lattice consists of 24 TME cells with two dispersion suppressors. Initial design of the magnets, power supply specifications, Eddy current contribution to the booster chromaticity are discussed.  
RPAP014 Uniform Irradiation Systems Using a Rotatable Stage for Test Facilities of PEFP target, proton, simulation, cyclotron 1383
  • B.-S. Park, B.H. Choi, K. R. Kim, S.-K. Lee
    KAERI, Daejon
  Funding: This work is a part of the "Proton Engineering Frontier Project" which is sponsored by the Ministry of Science and Technology of Korea under '21C Frontier R&D Program."

A new irradiation facility has been developed using not only electric magnets but also a rotatable stage. Generally, the scanning method using magnet has been widely used in most of facilities. However, in this study another new methods have been developed: Three scanning method using rotatable stage have been proved to make uniform irradiation-as large as 20 cm in diameter with more than 90% uniformity. The mechanical wobbler system makes the same effect as the wobbler system. And the beam is swept along the spiral path with a fixed and variable angular frequency during the scanning in two spiral scanning systems, respectively.

RPAP032 Hardware Tracking Related to Compact Medical Pulse Synchrotron synchrotron, quadrupole, proton, acceleration 2260
  • K. Endo, K. Egawa, Z. Fang
    KEK, Ibaraki
  • S. Yamanaka
    NIRS, Chiba-shi
  A compact 200 MeV proton synchrotron for the radiotherapy is being developed. Dipole and quadrupole magnets were already manufactured and are ready to measure their field properties under the pulse excitation. Preliminary field measurement was already done on the prototype dipole. Small RF cavity with a wide bandwidth (2~18 MHz) was successfully developed. Concerning to the simultaneous pulse operation of these components, there are some issues to be solved beforehand. These are the tracking between dipole field and the quadruple field gradient, the RF frequency generation sensing the dipole current (or field), the sextupole field correction of the dipole and etc. These issues studied experimentally using the dipole current will be presented in conjunction with the progress of the development.  
RPAT001 Experimental Results of a Non-Destructive Emittance Measurement Device for H- Beams ion, emittance, laser, simulation 782
  • C. Gabor, H. Klein, O. Meusel, U. Ratzinger
    IAP, Frankfurt-am-Main
  • J. Pozimski
    Imperial College of Science and Technology, Department of Physics, London
  For the diagnostic of high power ion beams, non-destructive measurement devices should not only provide minimum influence on the beam itself, but also avoid various problems that occur when the high power density of the beam penetrates surfaces like slit- or pinhole plates. On the other hand, measurements of resolution should be comperable with destructive methods. Beams of negative ions offer the use of a non-destructive Emittance Measurement Instrument (EMI) based on the principle of photo detachment. Interaction of laser photons with the negative ions causes electron detachment. Due to moving the postion of the well collimated laser beam acros the ion beam the produced neutral atoms are well suited to detect the transverse beam emittance like a classical slit-grid device. After separation in a magnetic dipole, the neutrals can be viewed on a scintillator screen with a CCD camera. To investigate the use of such a photo detachment EMI and to study the transport of negative ions an experiment consisting of H minus ion source, electrostatic LEBT and EMI was constructed. The paper will present the setup of the experimental hardware and first results of measurements.  
RPAT033 Beta Function Measurement in the Tevatron Using Quadrupole Gradient Modulation quadrupole, coupling, lattice, emittance 2272
  • A. Jansson, P. Lebrun, J.T. Volk
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. Department of Energy.

Early in Run2, there was an effort to compare the different emittance measurements in the Tevatron (flying wires and synchtotron light) and understand the origin of the observed differences. To measure the beta function at a few key locations near the instruments, air-core quadrupoles were installed. By modulating the gradient of these magents and measuring the effect on the tune, the lattice parameters can be extracted. Initially, the results seem to disagree with with other methods. At the time, the lattice was strongly coupled due to a skew component in the main dipoles, caused by sagging of the cryostat. After a large fraction of the superconducting magnets were shimmed to remove a strong skew quadrupole component, the results now agree with expectations, confirming that the beta function is not the major error source of discrepancy in the emittance measurement.

RPAT040 Matching BPM Stripline Electrodes to Cables and Electronics impedance, SNS, simulation, linac 2607
  • C. Deibele
    ORNL, Oak Ridge, Tennessee
  • S.S. Kurennoy
    LANL, Los Alamos, New Mexico
  Funding: This work was supported by SNS through UT-Batelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built at Oak Ridge National Laboratory. The 805-MHz coupled-cavity linac (CCL) accelerates an H- beam from 86 to 186 MeV, while the 805 MHz superconducting-cavity linac (SCL) accelerates the beam to its final energy of 1 GeV. The SNS beam position monitors (BPMs) which are used to measure both position and phase of the beam relative to the master oscillator, have the dual-planed design with four one-end-shorted stripline electrodes. We argue that the BPMs are optimally broadband matched to the cabling and electronics when the geometrical mean of the sum-mode and quadrupole-mode impedances is equal to the external-line impedance, 50 Ohms. The analytical results, MAFIA and HFSS simulations, wire measurements, and beam measurements that support this statement are presented.

RPAT064 Beam-Based Calibration of the Electron Energy in the Fermilab Electron Cooler electron, antiproton, vacuum, kicker 3638
  • S. Seletsky
    Rochester University, Rochester, New York
  • A.V. Shemyakin
    Fermilab, Batavia, Illinois
  Electron cooling of 8.9 GeV antiprotons in the Fermilab’s Recycler ring requires precise matching of electron and antiproton velocities. While the final match can be done by optimization of the cooling process, for the very first cooling one should rely on the knowledge of absolute values of electron and antiproton energies. The upper limit for the energy uncertainty of both beams is determined by the Recycler’s momentum aperture and is equal to 0.3%. The paper discusses a method of the electron energy calibration that is based on the measurement of the electron’s Larmor wavelength in the field of the cooling section solenoid. The method was tested in an 18 m long cooling section prototype with 3.5 MeV electrons. An accuracy of 0.3% was demonstrated.  
RPAT072 The General ElectroN Induced Emission (GENIE) System electron, simulation, beam-transport, emittance 3877
  • M.A. Epps, R. Kazimi
    Jefferson Lab, Newport News, Virginia
  • P.L. Gueye
    Hampton University, Hampton, Virginia
  A real time beam diagnostic system is proposed for the Jefferson Lab injector region. The General ElectroN Induced Emission System (GENIE) is a package that includes both hardware (beam monitoring devices) and software (for 3D or 4D visualization of the beam transport). This beam diagnostic tool relies primarily on the use of (very small) scintillating fibers placed in different planes to extract the beam profile, beam position, beam current and beam emittance in real time. Accuracies in position and angle could be at the sub- μm and μrad levels, respectively. The beam current could be reconstructed within a few percent. A combined Geant4/Parmela simulation will be developed for beam optic studies. While Parmela offers the power of beam transport with phase matching capabilities (among others), Geant4 provides the power for tracking secondary particles, as well as 3D & 4D visualization. A phase I investigation of GENIE using a 100 keV beam line is discussed in this document.  
RPAT085 Initial Imaging of 7-GeV Electron Beams with OTR/ODR Techniques at APS radiation, booster, electron, beam-losses 4162
  • A.H. Lumpkin, W. Berg, N. Sereno, C. Yao
    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.

The development of nonintercepting (NI) diagnostics continues to be of interest at the Advanced Photon Source (APS) as well as elsewhere. In the three rings of the APS facility we use optical synchrotron radiation generated as the electron beam transits the dipole magnetic fields as an NI mechanism to image the beam during top-up operations. However, in the straight transport lines an alternative method is needed. Optical diffraction radiation (ODR) is under investigation to monitor 7-GeV beam trajectory and potentially transverse shape in the booster-to-storage ring (BTS) beamline during top-up operations. We have performed our initial measurements with an Al blade/mirror that served as an optical transition radiation (OTR) monitor when fully inserted into the beam and as an ODR monitor when the beam passed near the edge. In the case of ODR, appreciable signal is emitted by the metal when gamma times the reduced ODR wavelength is comparable to the impact parameter, where gamma is the Lorentz factor. Visible light optics and a standard CCD camera could thus be used for a few-mm impact parameter. We attribute the near-field signal for 1.5- to 3.0-mm impact parameters predominately to the ODR mechanism.

RPAT096 High-Precision Resonant Cavity Beam Position, Emittance and Third-Moment Monitors quadrupole, coupling, impedance, sextupole 4311
  • N. Barov, J.S. Kim, A.W. Weidemann
    Far-Tech, Inc., San Diego, California
  • R.H. Miller, C.D. Nantista
    SLAC, Menlo Park, California
  Funding: Work supported by the U.S. Dept. of Energy.

Linear colliders and FEL facilities need fast, nondestructive beam position and profile monitors to facilitate machine tune-up, and for use with feedback control. FAR-TECH, Inc. is developing a resonant cavity diagnostic to simultaneously measure the dipole, quadrupole and sextupole moments of the beam distribution. Measurements of dipole and quadrupole moments at multiple locations yield information about beam orbit and emittance. The sextupole moment can reveal information about beam asymmetry which is useful in diagnosing beam tail deflections caused by short range dipole wakefields. In addition to the resonance enhancement of a single-cell cavity, use of a multi-cell standign-wave structure further enhances signal strength and improves the resolution of the device. An estimated rms beam size resolution is sub micro-meters and beam position is sub nano-meter.

ROPB003 Electron Cloud Dynamics in High-Intensity Rings electron, SNS, quadrupole, space-charge 245
  • L. Wang, J. Wei
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy. SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

Electron cloud due to beam induced multipacting is one of the main concerns for the high intensity rings because the electron multipacting becomes stronger with the increment of beam intensity. Electrons generated and accumulated inside the beam pipe form an "electron cloud" that interacts with the circulating charged particle beam. With sizeable amount of electrons, this interaction can cause beam instability, beam loss and emittance growth. At the same time, the vacuum pressure will rise due to electron desorption. This talk intends to provide an overview of the dynamics of the typical electron multipacting in various magnetic fields and mitigation measures in both long bunch and short bunch rings.

ROPB004 Effect of Lattice and Electron Distribution in Electron-Cloud Instability Simulations for the CERN SPS and LHC electron, emittance, lattice, simulation 387
  • E. Benedetto, E. Benedetto
    Politecnico di Torino, Torino
  • G. Arduini, F. Roncarolo, F. Zimmermann
    CERN, Geneva
  • B. Feng, A.F. Ghalam, T.C. Katsouleas
    USC, Los Angeles, California
  • G. Franchetti
    GSI, Darmstadt
  • K. Ohmi
    KEK, Ibaraki
  • G. Rumolo
    CELLS, Bellaterra (Cerdanyola del Vallès)
  Several simulation codes have been adapted so as to model the single-bunch electron-cloud instability including a realistic variation of the optical functions with longitudinal position. In addition, the electron cloud is typically not uniformly distributed around the ring, as frequently assumed, but it is mainly concentrated in certain regions with specific features, e.g., regions which give rise to strong multipacting or suffer from large synchrotron radiation flux. Particularly, electrons in a dipole magnet are forced to follow the vertical field lines and, depending on the bunch intensity, they may populate two vertical stripes, symmetrically located on either side of the beam. In this paper, we present simulation results for the CERN SPS and LHC, which can be compared with measurements or analytical predictions.  
ROPB010 Self-Consistent Electron-Cloud Simulation for Long Proton Bunches proton, electron, simulation, lattice 722
  • A.P. Shishlo, S.M. Cousineau, V.V. Danilov, S. Henderson, J.A. Holmes, Y. Sato
    ORNL, Oak Ridge, Tennessee
  • S.-Y. Lee
    IUCF, Bloomington, Indiana
  • R.J. Macek
    LANL, Los Alamos, New Mexico
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The results of numerical electron-cloud simulations for long-bunch proton beams in accumulator rings are presented and compared with data from the Proton Storage Ring at LANL. The frequency spectra and growth rate of proton-bunch transverse instabilities are studied as functions of the RF cavity voltage, external magnetic fields, beam pipe surface properties, and other factors. We used the recently developed electron-cloud module in the ORBIT code. The model includes a fully self-consistent coupled treatment of the "proton bunch – electron-cloud" dynamics and the multipacting process with a realistic secondary emission surface model. Realistic lattices and proton bunch distributions are used. The efficiency of electron-cloud instability suppression has also been studied using a new ORBIT model.

RPPE037 The Vacuum System for PETRA III radiation, vacuum, synchrotron, undulator 2473
  • M. Seidel, R. Bospflug, J. Boster, W. Giesske, U. Naujoks, M. Schwartz
    DESY, Hamburg
  It is planned to rebuild the storage ringe PETRA II, presently used as pre-accelerator of HERA, into a high performance synchrotron light source. By making use of the large circumference and the installation of damping wigglers it will be possible to achieve exceptionally small emittances in the new storage ring. The requirements for the vacuum system are more advanced in the new storage ring as well. Besides the goal to achieve low pressures and fast conditioning times a major key for the new ring is a very high orbit stability which implies high thermal stability of BPM's and other vacuum components. We describe the basic concepts for chamber layout, pumping schemes, synchrotron radiation absorption and mechanical stability for the standard arcs and the experimental octant. Furthermore the expected performance will be discussed.  
RPPE039 Alumina Ceramics Vacuum Duct for the 3GeV-RCS of the J-PARC impedance, vacuum, electron, quadrupole 2604
  • M. Kinsho
    Japan Atomic Energy Institute, Linac Laboratory, Tokai-Mura
  • Z. Kabeya
    MHI, Nagoya
  • N. Ogiwara
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • Y. Saito
    KEK, Ibaraki
  It was success to develop alumina ceramics vacuum ducts for the 3GeV-RCS of J-PARC at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5m-long duct with a circular cross section for use in the quadrupole magnet, the other being 3.5m-long and bending 15 degrees, with a race-track cross section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.5-0.8 m in length by brazing. The alumina ceramics ducts have copper stripes on the outside surface of the ducts to reduce the duct impedance. One of the ends of each stripe is connected to a titanium flange by way of a capacitor so to interrupt an eddy current circuit. The copper stripes are produced by an electroforming method in which a stripe pattern formed by Mo-Mn metallization is first sintered on the exterior surface and then overlaid by PR-electroformed copper (Periodic current Reversal electroforming method). In order to reduce emission of secondary electrons when protons or electrons strike the surface, TiN film is coated on the inside surface of the ducts.  
RPPE044 Vacuum Modifications for the Installation of a New CESR-c Fast Luminosity Monitor vacuum, luminosity, photon, synchrotron 2836
  • Y. Li, Y. He, M.A. Palmer
    Cornell University, Department of Physics, Ithaca, New York
  Funding: Work supported by the National Science Foundation.

In order to improve luminosity tuning and maintenance for the CLEO-c high energy physics (HEP) program at the Cornell Electron Storage Ring (CESR), a luminosity monitor using photons from radiative Bhabha events has been installed in the CESR ring. Over 10 meters of CESR vacuum chambers near the interaction region were modified to accommodate this new device. The vacuum modifications were designed to meet two criteria. First, the new vacuum chambers had to provide sufficient horizontal and vertical aperture for photons originating from the IP over a wide range of colliding beam conditions. Secondly, the new vacuum chambers required adequate safety margins for operation at beam energies up to 5.3 GeV for Cornell High Energy Synchrotron Source running. In order to be certain that the vacuum modifications would not give rise to any localized pressure bumps, a detailed calculation of the expected vacuum pressure distribution due to synchrotron radiation flux was carried out. Careful design and planning enabled a successful installation and resumption of CESR operations in record time.

RPPE046 A Summary and Status of the SNS Ring Vacuum Systems vacuum, injection, quadrupole, target 2929
  • M. Mapes, H.-C. Hseuh, J. Rank, L. Smart, R.J. Todd, D. Weiss
    BNL, Upton, Long Island, New York
  • M.P. Hechler, P. Ladd
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The Spallation Neutron Source (SNS) ring is designed to accumulate high intensity protons. The SNS ring vacuum system consists of the High Energy Beam Transport (HEBT) line, Accumulator Ring and the Ring to Target Beam Transport (RTBT) line. The Accumulator ring has a circumference of 248m with 4 arcs and 4 straight sections, while the RTBT and HEBT have a total length of 350m of beam transport line. Ultrahigh vacuum of 10-9 Torr is required in the accumulator ring to minimize beam-residual gas ionization. To reduce the secondary electron yield (SEY) and the associated electron cloud instability, the ring vacuum chambers are coated with Titanium-Nitride (TiN). This paper describes the design, fabrication, assembly and vacuum processing of the ring and beam transport vacuum systems as well as the associated instrumentation and controls.

RPPE063 Concepts for the JLab Ampere-Class CW Cryomodule damping, SNS, vacuum, linac 3588
  • R.A. Rimmer, E. Daly, J. Henry, W.R. Hicks, J.P. Preble, M. Stirbet, H. Wang, K. Wilson, G. Wu
    Jefferson Lab, Newport News, Virginia
  Funding: This manuscript has been authored by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy, and by The Office of Naval Research under contract to the Dept. of Energy.

We describe the concepts and developments underway at JLab as part of the program to develop a new CW cryomodule capable of transporting ampere-level beam currents in a compact FEL. Requirements include real-estate gradient of at least 10 MV/m and very strong HOM damping to push BBU thresholds up by two or more orders of magnitude compared to existing designs. Cavity shape, HOM damping, power couplers, tuners etc. are being designed and optimized for this application. Cavity considerations include a large iris for beam halo, low-RF losses, HOM frequencies and Q’s, low peak surface fields, field flatness and microphonics. Module considerations include high packing factor, low static heat leak, image current heating of beam-line components, cost and maintainability. This module is being developed for the next generation ERL based high power FELs but may be useful for other applications such as electron cooling, electron-ion colliders, industrial processing etc.

RPPE075 Injector Electronics for Multi-Turn Operation of the University of Maryland Electron Ring (UMER) injection, electron, beam-losses, cathode 3952
  • M. Holloway, T.F. Godlove, P.G. O'Shea, B. Quinn, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by U.S. Department of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

Progress is described toward the development of pulse generators required for injection and extraction of the University of Maryland Electron Ring (UMER). The geometry, described elsewhere, employs a fast ironless dipole at the junction of a Y-shaped section of the ring. The dipole as developed has an inductance of 600 nH. The required +21 A, long pulse generator for multi-turn operation is installed. A pulser providing -42 A for deflection in the opposite sense during injection is under development. It must have a fall time of ~100 ns in view of the 200 ns circulation time for the beam. A similar pulser, having a 100 ns risetime is required for beam extraction. The fast pulsers employ MOSFET switches.

RPPE076 Overview of Electrical Systems for the University of Maryland Electron Ring (UMER) quadrupole, injection, electron, cathode 3988
  • B. Quinn, G. Bai, S. Bernal, T.F. Godlove, I. Haber, J.R. Harris, M. Holloway, H. Li, J.G. Neumann, P.G. O'Shea, K. Tian, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by the United States Department of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

Commissioning of the University of Maryland Electron Ring (UMER) is underway (see general abstract on UMER). We discuss the various electrical systems of UMER. The power system includes 114 supplies for 70 air-core magnetic quadrupoles, 36 bending dipoles and 30+ steering dipoles as well as earth's field compensating coils. Systems for data collection comprise multiplexers and fast digitizers for diagnostics including 15 fast beam position monitors (BPMs)and video capture from fluorescent screen monitors. Several pulsers have been built in-house for injection and extraction magnets. The stringent timing schemes are also presented.

RPPP042 Emittance Dilution Due to Dipole Mode Rotation and Coupling in the Main Linacs of the ILC emittance, linac, simulation, coupling 2723
  • R.M. Jones, R.H. Miller
    SLAC, Menlo Park, California
  Funding: This work is supported by Department of Energy grant number DE-AC02-76SF00515.

The progress of multiple bunches of charged particles down the main L-band linacs of the ILC (International Linear Collider) can be disrupted by wakefields. These wakefields correspond to the electromagnetic fields excited in the accelerating cavities and have both long-range and short-range components. Here we investigate the impact of the long-range wakefields on the trailing bunches caused by the leading bunches. In general, the dipole mode degeneracy will be removed both because of manufacturing errors and because the higher order mode couplers are dipole asymmetric and lie neither in the horizontal nor vertical plane. This creates 2 dipole eigenmodes which are rotated with respect to the horizontal and vertical axes and which may have slightly different frequencies. These eigenmodes can couple the horizontal and vertical dipole excitations. We simulate the progress of the ILC beam down the collider under the influence of these wakefields. In particular, we investigate the consequences on the final emittance dilution of the beam of coupling of the horizontal to the vertical motion of the beam.

RPPP043 Emittance Dilution Due to Many-Band Long-Range Dipole Wakefields in the International Linear Collider Main Linacs emittance, linac, simulation, linear-collider 2792
  • R.M. Jones
    SLAC, Menlo Park, California
  • N. Baboi
    DESY, Hamburg
  Funding: This work is supported by Department of Energy grant number DE-AC02-76SF00515.

We investigate the emittance dilution that occurs due to long range wakefields in the ILC L-band linacs. The largest kick factors (proportional to the transverse fields which transversely kick the beam off axis) from the first six bands are included in our simulations. These higher order dipole modes are damped by carefully orientating higher order mode couplers at both ends of each cavity. We investigate the dilution in the emittance of a beam with a random misalignment of cavities down the complete linac. In particular, the impact of a poorly damped dipole mode, on the overall emittance dilution down the complete linac is focused upon. The transverse alignment tolerances imposed on the cavities due to these wakefields are also discussed.

RPPP045 Single-Bunch Instability Driven by the Electron Cloud Effect in the Positron Damping Ring of the International Linear Collider electron, single-bunch, simulation, damping 2884
  • M.T.F. Pivi, T.O. Raubenheimer
    SLAC, Menlo Park, California
  • A.F. Ghalam
    USC, Los Angeles, California
  • K.C. Harkay
    ANL, Argonne, Illinois
  • K. Ohmi
    KEK, Ibaraki
  • R. Wanzenberg
    DESY, Hamburg
  • A. Wolski
    LBNL, Berkeley, California
  • F. Zimmermann
    CERN, Geneva
  Funding: Work supported by the U.S. DOE under contracts DE-AC02-76SF00515.

With the recommendation that the future International Linear Collider (ILC) should be based on superconducting technology, there is considerable interest in exploring alternate designs for the damping rings (DR). The TESLA design was 17 km in circumference with a "dog-bone" configuration. Two other smaller designs have been proposed that are 6 km and 3 km in length. In the smaller rings, collective effects may impose the main limitations. In particular for the positron damping ring, an electron cloud may be produced by ionization of residual gas or photoelectrons and increase through the secondary emission process. The build-up and development of an electron cloud is more severe with the higher average beam current in the shorter designs. In this paper, we present recent computer simulation results for the electron cloud build-up and instability thresholds for the various DR configurations.

RPPT020 Space Charge Effects for the ERL Prototype Injector Line at Daresbury Laboratory emittance, space-charge, linac, quadrupole 1676
  • B.D. Muratori, H.L. Owen
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • C. Gerth
    DESY, Hamburg
  • M.J. de Loos, S.B. van der Geer
    PP, Soest
  Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will operate at a beam energy of 35 MeV. In this paper we examine the space charge effects on the beam dynamics in the ERLP injector line. A Gaussian particle distribution is tracked with GPT (General Particle Tracer) through the injection line to the main linac to calculate the effect of 3Dspace charge in the dipoles. The nominal beam energy in the injection line is 8.3 MeV and the bunch charge 80 pC. The effects of space charge on the transverse and longitudinal emittance are studied for various electron beam parameter settings.  
RPPT022 Optics for High Brightness and High Current ERL Project at BNL gun, electron, emittance, linac 1775
  • D. Kayran, I. Ben-Zvi, R. Calaga, X.Y. Chang, J. Kewisch, V. Litvinenko
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy and partially funded by the US Department of Defence

An energy recovery linac (ERL), under development at Brookhaven National Laboratory [1,2], will push ERLs further towards high current and high brightness beams. This R&D ERL will operate in two modes: a high current mode and a high charge mode. In this paper we present a lattice of the machine and PARMELA simulations from the cathode to the beam dump. We discuss the design considerations and present main parameters for various modes of operation.

FPAE006 Optimization of AGS Polarized Proton Operation with the Warm Helical Snake proton, extraction, resonance, simulation 1003
  • J. Takano, M. Okamura
    RIKEN, Saitama
  • L. Ahrens, M. Bai, K.A. Brown, C.J. Gardner, J. Glenn, H. Huang, A.U. Luccio, W.W. MacKay, T. Roser, S. Tepikian, N. Tsoupas
    BNL, Upton, Long Island, New York
  • T. Hattori
    RLNR, Tokyo
  Funding: US DOE and RIKEN Japan.

A normal conducting helical dipole partial Siberian snake (Warm Snake) has been installed in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL) for overcoming all of imperfection depolarizing resonances and reducing the transverse coupling resonances caused by the solenoidal Siberian snake which had been operated in AGS before the last polarized run. The polarized proton beam has been accelerated successfully with the warm snake and the polarization at extraction of the AGS was increased to 50% as opposed to 40% with the solenoidal snake. The magnetic field and beam trajectory in the warm snake was calculated by using the OPERA-3D/TOSCA software. We present optimization of the warm snake with beam during RUN5.

FPAE013 Calculation of the Orbit Length Change of the Recycler Due to Main Injector Ramp closed-orbit, lattice, kicker, betatron 1318
  • M. Xiao
    Fermilab, Batavia, Illinois
  Orbit length of beam in the Recycler changes during the Main Injector ramps. The unknown kicks from the effects generated by stray field are distributed around the ring. To estimate the changes, simulated virtual kicks are created around each lambson, C-magnet and bus cable of the Main Injector. The orbit lengths are calculated from measurements of evolution frequency and transverse beam positions. A BPM system distributed throughout the Recycler lattice in both Horizontal and vertical planes are used to take the closed orbit measurement during the ramps. The calculation method and the results of the orbit length changes and the strength of the simulated kicks are presented in this report.  
FPAE014 Acceleration of Polarized Protons in the AGS with Two Helical Partial Snakes resonance, polarization, extraction, injection 1404
  • H. Huang, L. Ahrens, M. Bai, A. Bravar, K.A. Brown, G. Bunce, E.D. Courant, C.J. Gardner, J. Glenn, R.C. Gupta, A.U. Luccio, W.W. MacKay, V. Ptitsyn, T. Roser, S. Tepikian, N. Tsoupas, E. Willen, A. Zelenski, K. Zeno
    BNL, Upton, Long Island, New York
  • F. Lin
    IUCF, Bloomington, Indiana
  • M. Okamura
    RIKEN/RARF/CC, Saitama
  • J. Takano
    RIKEN, Saitama
  • D.G. Underwood
    ANL, Argonne, Illinois
  • J. Wood
    UCLA, Los Angeles, California
  Funding: Work supported by U.S. DOE and RIKEN of Japan.

The RHIC spin program requires 2*1011 proton/bunch with 70% polarization. As the injector to RHIC, AGS is the bottleneck for preserving polarization: there is not enough space in the ring to install a full snake to overcome the numerous depolarizing resonances. An ac dipole and a partial Siberian snake have been used to preserve beam polarization in the past. The correction with this scheme is not 100% since not all depolarizing resonances can be overcome. Recently, two helical snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate all depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.

FPAE021 Alignment and Steering for Injection and Multi-Turn Operation of the University of Maryland Electron Ring (UMER) injection, quadrupole, electron, alignment 1709
  • M. Walter, G. Bai, S. Bernal, I. Haber, M. Holloway, R.A. Kishek, P.G. O'Shea, B. Quinn
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by US Dept. of Energy grant numbers DE-FG02-94ER40855 and DE-FG02-92ER54178.

The injection line and main lattice for the University of Maryland Electron Ring (UMER) has been completed. The electron beam has been guided around the full 360 degrees of the ring. Beam steering and matching in the injection line is achieved with six quadrupole magnets and several small steering dipole magnets. The dipole component of an offset quadrupole and a pulsed dipole are used to achieve the 10 degree bend required from the injection line into the ring. The pulsed dipole is designed to operate with a short pulse (2 kV, -30 A, 100 ns flat top duration) for injection superimposed on a long pulse (300 V, 15 A, 20·10-6 s duration) for multiple beam passes. The beam is controlled in the recirculating ring with a regular lattice of 36 dipole and 72 quadrupole magnets. Initial experimental results of the beam transport and control will be presented.

FPAE044 Test Results of the PEFP 3MeV RFQ Upgrade rfq, proton, klystron, coupling 2842
  • Y.-S. Cho, S.-H. Han, J.-H. Jang, H.-S. Kim, Y.-H. Kim, H.-J. Kwon, M.-Y. Park, K.T. Seol
    KAERI, Daejon
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

A 3MeV RFQ upgrade for 100MeV proton accelerator has been fabricated at PEFP (Proton Engineering Frontier Project). The tuning of the cavity was carried out before and after the brazing to meet the condition that the quadrupole field profile is within 1% of design value and dipole component is less than 1% of quadrupole one. The ancillary system such as high power RF including klystron power supply and cooling system were already tested up to operating level. Therefore, the main issues of the tests were cavity conditioning up to full power level and low duty beam test. After the completion of the beam test of RFQ itself, the 20MeV DTL which has been tested independently will be carried out. In this paper, the test results of the PEFP 3MeV RFQ upgrade including high power conditioning and low duty beam acceleration are presented.

FPAE075 Radiation Damage to the Elements of the SIS300 Dipoles ion, extraction, radiation, simulation 3943
  • E. Mustafin, J. Kaugerts, G. Moritz, G. Walter
    GSI, Darmstadt
  • L.N. Latysheva, N. Sobolevskiy
    RAS/INR, Moscow
  Funding: Supported by the grant of the GSI-INTAS Project #03-54-3588.

Radiation damage to various elements of the cosine-theta type dipoles of the SIS300 synchrotron of the FAIR Project was calculated. Among the elements under consideration were the superconducting cable, insulating materials, and high-current by-pass protection diodes. The Monte-Carlo particle transport codes MARS and SHIELD were used to simulate propagation of the lost ions and protons, together with the products of nuclear interactions in the material of the elements. It was found that the lifetime of the protection diodes under irradiation is a more restrictive limit for the tolerable level of beam losses than the occurrence of magnet quenches.

FPAP004 Simulation Analysis of Head-Tail Motion Caused by Electron Cloud electron, simulation, feedback, betatron 907
  • K. Ohmi, J.W. Flanagan, H. Fukuma, S. Hiramatsu, H. Ikeda, M. Tobiyama
    KEK, Ibaraki
  • E. Perevedentsev
    BINP SB RAS, Novosibirsk
  Synchro-beta side band caused by electron cloud instability has been observed at KEK-B factory. The side-band appears between $νβ+νs$ and $νβ+2νs$ above the threshold of beam size blow up and disappear by applying solenoid field. The side-band is an evidence of strong head-tail instability caused by electron cloud. The side-band is characterized by positive shift, $+1-2νs$, while general strong head-tail instabilities give frequency with negative shift $νbeta-ν_s$. We study the synchro-beta spectrum using a code, PEHTS, which simulates single bunch electron cloud instability.  
FPAT002 Automatic Steering for the CTF3 Linear Accelerator simulation, linac, focusing, lattice 814
  • R.D. Lifshitz
    Technion, Haifa
  • D. Schulte
    CERN, Geneva
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395)

A system for automatic beam steering has been implemented at the CTF3 linear accelerator. Beam position readings are logged while corrector magnet strengths are scanned over a given range, thus giving a steering response measurement. Assuming linearity, a response matrix is constructed and used to automatically optimize the beam trajectory along the linac. Using a simple BPM-reading minimization for trajectory correction, this system has been tested in the 2004 CTF3 summer run. Although not in routine operation, it has already proved useful as a tool for the machine setup and operation. In this paper, the automatic steering system for the CTF3 linac is introduced, trajectory correction results are presented, and the agreement with a computer model of the machine is discussed.

FPAT015 Beam Trajectory Correction for SNS SNS, linac, Spallation-Neutron-Source, beam-losses 1425
  • C. Chu, T.A. Pelaia
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

Automated beam trajectory correction with dipole correctors is developed and tested during the Spallation Neutron Source warm linac commissioning periods. The application is based on the XAL Java framework with newly developed optimization tools. Also, dipole corrector polarities and strengths, and beam position monitor (BPM) polarities were checked by an orbit difference program. The on-line model is used in both the trajectory correction and the orbit difference applications. Experimental data for both applications will be presented.

FPAT044 Low Cost Magnetic Field Controller power-supply, permanent-magnet, controls, microtron 2833
  • A.A. Malafronte, M.N. Martins
    USP/LAL, Bairro Butantan
  Funding: Fundacao de Amparo a Pesquisa do Estado de Sao Paulo-FAPESP, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq.

The Physics Institute of the University of São Paulo (IFUSP) is building a continuous wave (cw) racetrack microtron. This machine has several dipole magnets, like the first and second stage recirculators, and a number of smaller ones in the transport line. These magnets must produce very stable magnetic fields to allow the beam to recirculate along very precise orbits and paths. Furthermore, the fields must be reproducible with great accuracy to allow an easier setup of the machine, though the effects of hysteresis tend to jeopardize the reproducibility. If the magnetic field is chosen by setting the current in the coils, temperature effects over the magnet and power supply tend to change the field. This work describes an inexpensive magnetic field controller that allows a direct measure of the magnetic field through an Hall probe. It includes a microcontroller running a feedback algorithm to control the power supply, in order to keep the field stable and reproducible. The controller can also execute algorithms to ramp up and down the power supply in a specific mode, in order to reduce hysteresis.

FOAD005 Commissioning of the University of Maryland Electron Ring (UMER) injection, space-charge, quadrupole, emittance 469
  • S. Bernal, G. Bai, D.W. Feldman, R. Feldman, T.F. Godlove, I. Haber, J.R. Harris, M. Holloway, R.A. Kishek, J.G. Neumann, P.G. O'Shea, C. Papadopoulos, B. Quinn, D. Stratakis, K. Tian, J.C. Tobin Thangaraj, M. Walter, M. Wilson
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by the U.S. Department of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178, and the office of Naval Research under grant N00014-02-1-0914.

The University of Maryland electron ring (UMER) is a low-energy, high current recirculator for beam physics research. The ring is completed for multi-turn operation of beams over a broad range of intensities and initial conditions. UMER is addressing issues in beam physics with relevance to many applications that rely on intense beams of high quality. Examples are advanced accelerators, FEL’s, spallation neutron sources and future heavy-ion drivers for inertial fusion. We review the motivation, ring layout and operating conditions of UMER. Further, we present a summary of beam physics areas that UMER is currently investigating and others that are part of the commissioning plan: from transverse beam dynamics (matching, halo formation, strongly asymmetric beams, space-charge waves, etc), longitudinal dynamics (bunch capture/shaping, evolution of energy spread, longitudinal space-charge waves, etc.) to future upgrades and planned research (acceleration and resonance traversal, modeling of galactic dynamics, etc.) We also emphasize the computer simulation work that is an integral part of the UMER project.

FOPA003 Challenges and Progress in the FAIR Accelerator Project ion, antiproton, synchrotron, proton 294
  • P.J. Spiller
    GSI, Darmstadt
  An international "Facility for Antiproton and Ion Research (FAIR)" was proposed to be built at GSI, providing unique conditions for experiments involving heavy ion and antiprotons beams. The new accelerator complex consists of the fast ramped s.c. heavy ion synchrotrons, SIS100/300 and a storage ring system for experiments with radioactive ions and antiprotons. The two stage concept for SIS100/300 provides optimum conditions for the generation of beams with high intensities per cycle and in average, over a wide energy range and with various time structures. Bunch compression enables a matching to the production targets and storage rings. The storage ring complex was optimized for fast cooling and accumulation of the generated secondary beams. Unique conditions for internal target experiments with radioactive beams will be provided in NESR and for antiproton beams in the high energy storage ring HESR. The new accelerators require R&D work in various fields of technologies and beam physics, as e.g. operation with low charge state, high intensity, heavy ion beams in dynamic vacuum conditions, development of fast ramped s.c. magnets, powerful, low frequency rf systems, stochastic cooling systems and medium energy electron coolers.