THPE  —  Poster Session   (27-May-10   16:00—18:00)

Paper Title Page
THPE001 Low Emittance Lattice Optimization Using Multiobjective Genetic Algorithm 4515
 
  • W.W. Gao, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui
 
 

Low emittance is a desirable performance for high brightness synchrotron light source and damping ring. The work presented in this paper demonstrates that the lattice of a given electron storage ring, which has fixed circumference and magnet layout, can be optimized to obtain low emittance by using MOGA (Multi-objective Genetic Algorithm). Both dispersion-free and non-dispersion-free lattices of HLS (Hefei Light Source) upgrade project are computed as an illustration. Simulation result shows that this method is fast and straightforward.

 
THPE005 Beam Polarization Theory and its Application to HLS Storage Ring 4518
 
  • J.Q. Lan, B. Sun, Y.C. Sun, H. Xu
    USTC/NSRL, Hefei, Anhui
 
 

A brief, but clear, review of beam polarization theory is given in the paper. Particularly, the algorithm of spin linear transfer matrix (SLIM) is applied to remark the situation of beam in storage ring, specific to HLS (Hefei Light Source). Theoretical analysis indicates that the beam in HLS, working at 800MeV and 2.58/3.58 transverse tunes, could keep away from a variety of spin resonances, and should be able to build up high polarization.

 
THPE006 Closed Orbit Correction of Hefei Light Source (HLS) Upgrading Storage Ring 4521
 
  • S.C. Zhang, W. Fan, G. Feng, W.W. Gao, H. Geng, Z.G. He, W. Li, L. Wang, H. Xu
    USTC/NSRL, Hefei, Anhui
 
 

In order to meet the increasing requirements of synchrotron radiation users, an upgrading plan of hefei light source is undergoing by National Synchrotron Radiation Laboratory (NSRL). The emittance of storage ring is reduced from 166nm.rad to 36nm.rad. In this paper, we study the beam close orbit distortions' (COD) sensitivity to the field and alignment errors in magnets. Estimation of the COD from various error sources is investigated. The distribution of beam position monitors and the location of correctors are reported in the paper. Simulation proves that COD can be corrected down to 50 microns level. In the same time the corrector strengths are weaker enough in the correction scheme.

 
THPE007 The Upgrade of the Hefei Light Source (HLS) Transport Line 4524
 
  • S.C. Zhang, W. Fan, G. Feng, W.W. Gao, W. Li, L. Wang, H. Xu
    USTC/NSRL, Hefei, Anhui
 
 

To enhance the performance of Hefei Light Source, an upgrade project is undergoing. The magnet lattice of storage ring will be reconstructed with 4 DBA cells, whose advantages are lower beam emittance and more straight section available for insertion devices. In order to assure smooth beam accumulation process under new low emittance lattice, the injector, which is composed of electron linac and beam transfer line, would be updated. The detail of upgrading Hefei Light Source transport line will be described in this paper. It include the upgrading of lattice, the orbit control of beam transfer line and others. It is hopeful to realize a high transfer efficiency and high injection efficiency for new lower beam emittance storage ring.

 
THPE008 Issues on Beam Dynamics in PLS-II 4527
 
  • J.G. Hwang, S.W. Jang, E.-S. Kim
    Kyungpook National University, Daegu
 
 

Pohang Light Source-Ⅱ (PLS-Ⅱ) is an upgrade project of the existing 2.5 GeV PLS. The circumference, beam current and energy of PLS-Ⅱ storage ring are 281.82 m, 400 mA and 3 GeV, respectively. The upgrade project has many issues on beam dynamics. We investigated lattice optimization such as lattice corrections, dynamic aperture, selection of optimized tune & emittance and effects of insertion devices. MAD, SAD and Elegant have been used to the lattice optimization. We investigated the effects of machine errors and 20 IDs to the dynamic aperture. PLS-Ⅱ lattice include twenty insertion devices and their effects on the beam dynamics are investigated. We also investigate possibility to reduce the emittance by increasing horizontal betatron tune and adjusting the dispersion by using of MAD, SAD and Elegant and also examined the required strengths of sextupoles for the various emittances.

 
THPE009 Non-linear Beam Dynamics due to Sextupole in PEFP RCS 4530
 
  • S.W. Jang, E.-S. Kim
    Kyungpook National University, Daegu
 
 

Proton Engineering Frontier Project (PEFP) Linac has a plan of the addition of 1 GeV RCS ring. The lattice of the rapid cycling synchrotron is affected by a non-linear beam dynamics. In this study, we investigated about non-linear dynamics due to sextupoles in PEFP RCS. Notably, we investigated about 3rd integer resonance due to sextupoles. To slowly and continuously extract the proton beam, we utilize the 3rd integer resonance. For the reason, we investigated non linear beam dynamics due to 3rd integer resonance and slow extraction system by using of MAD8.

 
THPE011 Coupling Diagnostics and Control at PLS Storage Ring 4533
 
  • I. Hwang, C. Kim, K.R. Kim, M. Kim, S.H. Nam, S.J. Park, S. Shin
    PAL, Pohang, Kyungbuk
  • J. Hou, L.G. Liu
    SINAP, Shanghai
 
 

The measurement and the control of the coupling is essential to maximize synchrotron performance. Small coupling is required for small vertical size and high brightness. The Pohang Light Source has a 2.5 GeV storage ring and its coupling constant is measured as about 1%. In addition to errors at quadrupole or sextupole, the condition varying of the insertion device affects the coupling. The coupling for various condition is measured by the resonance and the response matrix and compared with the beam size and the lifetime. The correction and the control of the coupling is presented.

 
THPE012 U400 Cyclotron Spiral Inflector with Beam Vertical Focusing Effect 4536
 
  • I.A. Ivanenko, B. Gikal, G. Gulbekyan
    JINR, Dubna, Moscow Region
 
 

The main losses of the injected beam are localized at the centre region of the cyclotron. One of the problems is the defocusing action of the spiral inflector. At the present work the method of decreasing of the vertical defocusing effect of the spiral inflector is presented. The decreasing of the vertical defocusing is achieved by means of special form of the inflector electric field. At FLNR, JINR, the new type of the inflector was investigated and manufactured. At the present time the inflector is installed and works at the U400 cyclotron. The experiments with the new inflector have shown the increasing of the beam intensity and more tuneble work of the cyclotron.

 
THPE013 Invariants of Linear Equations of Motion 4539
 
  • N.Yu. Kazarinov
    JINR, Dubna, Moscow Region
 
 

Courant-Snyder invariant and Root Mean Square (RMS) beam emittance are well-known invariants of linear equation of motion. They are connected with the second order moments of a beam distribution function. Other invariants of linear equations of motion generated by second and higher order moments are presented in this report.

 
THPE014 Round Beam Lattice Correction using Response Matrix at VEPP-2000 4542
 
  • A.L. Romanov, D.E. Berkaev, I. Koop, A.N. Kyrpotin, E. Perevedentsev, Yu. A. Rogovsky, P.Yu. Shatunov, D.B. Shwartz
    BINP SB RAS, Novosibirsk
 
 

Lattice correction based on orbit responses to dipole correctors and orbit correction based on orbit responses to field gradient variations in quads were successfully implemented on VEPP-2000 [*] for the flat-beam lattice. The round-beam lattice involves strong coupling of vertical and horizontal motions that require a full-coupling analysis in the orbit response technique. Programs used were modified to treat this task. Also, automation and speed enhancements were done that enable a routine use of this technique at VEPP-2000. New experimental results from VEPP-2000 are presented.


* Yu.M.Shatunov et al. Project of a New Electron-Positron Collider VEPP-2000, in: Proc. 7th European Particle Accelerator Conf. (EPAC 2000), Vienna, Austria, 439-441

 
THPE015 Simplified Approach to Evaluation of Beam-beam Tune Spread Compression by Electron Lens 4545
 
  • A.L. Romanov
    BINP SB RAS, Novosibirsk
  • V.D. Shiltsev, A. Valishev
    Fermilab, Batavia
 
 

One of the possible ways to increase luminosity of hadron colliders is the compensation of beam-beam tune-spread with an electron lens (EL). At the same time, EL as an additional nonlinear element in the lattice can increase strength of nonlinear resonances so that its overall effect on the beam lifetime will be negative. Time-consuming numerical simulations are often used to study the effects of the EL. In this report we present a simplified model, which uses analytical formulae derived for certain electron beam profiles. Based on these equations the idealized shapes of the compressed tune spread can be rapidly calculated. Obtained footprints were benchmarked against several reference numerical simulations for the Tevatron in order to evaluate the selected configurations. One of the tested criteria was the so-called "folding" of the compensated footprint, which occurs when particles with different betatron amplitudes have the same tune shift. Also studied were the effects of imperfections, including misalignment of the electron and proton beams, and mismatch of their shapes.

 
THPE018 Layout and Optics Solution for the LHC Insertion Upgrade Phase I 4548
 
  • S.D. Fartoukh
    CERN, Geneva
 
 

The main guidelines of the LHC insertion (IR) upgrade Phase I are 1) the development of wider aperture (120 mm) and lower gradient (~120 T/m) quadrupoles using the well-characterized Nb-Ti technology in order to replace the existing inner triplets (IT) equipping the ATLAS and CMS high-luminosity IRs of the LHC, 2) while maximizing the use of the current LHC infrastructure, in particular leaving unchanged the so-called "matching sections" (MS) and "dispersion suppressors" (DS) of these two insertions. One of the initial goals was to be able to squeeze the optics up to a beta* of 25 cm. However, optics solutions with a beta* of 30 cm seems already to be at edge of achievability, both in terms of the IT and MS mechanical acceptance, gradients of the MS and DS quadrupole magnets, and correctability by the LHC arc sextupoles of the huge chromatic aberrations induced by the new inner triplet at ultimate beta*. The layout of the new inner triplet and the corresponding injection and collision optics will be presented and analyzed both in terms of aperture, squeeze-ability and chromatic correction.

 
THPE019 CERN Proton Synchrotron Working Point Matrix for Extended Pole Face Winding Powering Scheme 4551
 
  • P. Freyermuth, D.G. Cotte, M. Delrieux, H. Genoud, S.S. Gilardoni, K. Hanke, O. Hans, S. Mataguez, G. Metral, F.C. Peters, R.R. Steerenberg, B. Vandorpe
    CERN, Geneva
 
 

The CERN Proton Synchrotron has been continuously improving its beam performances since 1959. The working point parameters of the accelerator are mainly controlled by dedicated windings installed on the poles of the main combined function magnets. In 2007, the power supplies of these windings were renovated and extended from three to five independent groups, allowing exploration of new working point settings. This configuration offers the flexibility of several adjustment strategies such as leaving one current free or to control an additional physical parameter, like Q''h. A non-linear chromaticity measurement campaign, at different beam energies, resulted in matrices defining the relationship between the five pole face winding currents and the four beam parameters Qh, Qv, Xih, and Xiv. Each cell of these matrices was fitted against energy. The final result is a single matrix which is now used by the operational software to trim the working point. This paper summarises this measurement campaign by presenting the resulting matrix with a brief overview of the adjustment tools and strategy. Furthermore a few future possible benefits of this control enhancement will be discussed.

 
THPE020 Scenarios for the ATF2 Ultra-Low Betas Proposal 4554
 
  • E. Marin, R. Tomás
    CERN, Geneva
  • P. Bambade
    LAL, Orsay
  • S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • B. Parker
    BNL, Upton, Long Island, New York
  • A. Seryi, G.R. White, M. Woodley
    SLAC, Menlo Park, California
 
 

The current ATF2 Ultra-Low beta proposal was designed to achieve 20nm vertical IP beam size without considering the multipolar components of the FD magnets. In this paper we describe different scenarios that avoid the detrimental effect of these multipolar errors in the FD. The simplest approach consists in modifying the optics but other solutions are studied as the introduction of new higher order magnets or the replacement of the FD with SC technology. The practical aspects of such an upgrade are the tuning performance and the compatibility with existing devices and instrumentation. These are fully addressed in the paper.

 
THPE021 Comparison of PS2 Lattices with Different Geometries 4557
 
  • Y. Papaphilippou, W. Bartmann, H. Bartosik, M. Benedikt, B. Goddard, A. Lachaize
    CERN, Geneva
  • Y. Senichev
    FZJ, Jülich
 
 

The PS2 ring is designed with negative momentum compaction arc cells and doublet straights. In this paper, different lattice geometries are considered. In particular, a two-fold symmetric lattice with dispersion suppressors and a 3-fold symmetric one with resonant arc cells are compared with respect to their optics properties, and ability to satisfy space and magnet constraints. The tuning flexibility of rings based on these two options is presented. Finally, the impact of different geometries on resonance excitation and dynamic aperture is evaluated.

 
THPE022 Linear Optimization and Tunability of the PS2 Lattice 4560
 
  • H. Bartosik, W. Bartmann, M. Benedikt, B. Goddard, Y. Papaphilippou
    CERN, Geneva
 
 

The PS2 lattice, based on Negative Momentum Compaction (NMC) arc cells is being optimized in order to accommodate a new all-doublet long-straight section (LSS) design. Apart from smoothing the optics and enabling different tuning solutions for H- injection, the optimization focuses on increasing the available magnet-to-magnet drift space and reducing the quadrupole types and strengths. The variation of lattice parameters for a wide range of working points is presented.

 
THPE023 Non-Linear Analysis of the PS2 Negative Momentum Compaction Lattice 4563
 
  • H. Bartosik, M. Benedikt, Y. Papaphilippou
    CERN, Geneva
 
 

This paper describes a detailed analysis of various non-linear effects of the nominal Negative Momentum Compaction lattice for PS2. Chromaticity and orbit correction schemes together with dynamic aperture studies are presented. The impact of magnet errors is being assessed and tolerances are evaluated. Frequency and diffusion maps are produced and, combined with non-linear driving terms analysis, are used for working point optimization.

 
THPE024 Coupling and Vertical Dispersion Correction in the SPS 4566
 
  • G. Vanbavinckhove, M. Aiba, R. Tomás
    CERN, Geneva
  • R. Calaga
    BNL, Upton, Long Island, New York
 
 

Consolidation of the coupling correction scheme in the LHC is motivated due to a missing skew quadrupole family in Sector 3-4 at the start-up in 2009. Simultaneous coupling and vertical dispersion correction using vertical orbit bumps at the sextupoles, was studied by analyzing turn-by-turn data. This scheme was tested in SPS where the optical structure of arc cells is quite similar to the LHC. In SPS, horizontal and vertical beam positions are measured separately with single plane BPMs, thus a technique to construct "pseudo double plane BPM" is also discussed.

 
THPE025 Coupling and Vertical Dispersion Correction studies for the LHC using Skew Quadrupoles and Vertical Orbit Bumps 4569
 
  • G. Vanbavinckhove, M. Aiba, R. Tomás
    CERN, Geneva
  • R. Calaga
    BNL, Upton, Long Island, New York
 
 

After the incident in the LHC in 2008, few skew quadrupoles were damaged and subsequently removed from the tunnel. This could limit the correction of local coupling in the LHC. In order to increase the flexibility in the coupling correction it has been proposed to use of vertical orbit bumps at the sextupoles is studied. Moreover a simultaneous coupling and vertical dispersion can be implemented. Various studies are presented addressing the optimal approach for the correction of the vertical dispersion and the sum and difference coupling resonances.

 
THPE026 Software Package for Optics Measurement and Correction in the LHC 4572
 
  • G. Vanbavinckhove, M. Aiba, R. Tomás
    CERN, Geneva
  • R. Calaga
    BNL, Upton, Long Island, New York
 
 

A software package has been developed for the LHC on-line optics measurement and correction. This package includes several different algorithms to measure phase advance, beta functions, dispersion, coupling parameters and even some non-linear terms. A Graphical User Interface provides visualization tools to compare measurements to model predictions, fit analytical formula, localize error sources and compute and send corrections to the hardware.

 
THPE027 Construction and Performance of IP Optics Tuning Knobs in the LHC 4575
 
  • S.M. White, R. Tomás, G. Vanbavinckhove, W. Venturini Delsolaro
    CERN, Geneva
 
 

During the first years of operation of the LHC unknown field errors or misalignments could lead to unmatched optics and discrepancies with respect to the model. This could affect some critical parameters such as the luminosity or the lifetime. It is therefore desirable to implement tools which allow for fine tuning of the IP optics and could be used during the commissioning phase of the LHC. In this paper we report on the implementation the performances and the limitations of these commissioning tools.

 
THPE029 Studies of Insertion Device Modeling on TPS Project 4578
 
  • H.C. Chao, H.-P. Chang, C.-C. Kuo, H.-J. Tsai
    NSRRC, Hsinchu
 
 

In this paper, the simulation techniques of insertion device (ID) were discussed. Piecewise hard-edge model was used to estimate the tune shift and changes of emittance and energy spread, while kick map model was used for particle tracking. Optical functions and tune shifts can also be derived by this model. Frequency maps as well as the beta-beating and its correction of Phase I IDs are demonstrated.

 
THPE030 Double Mini-Betay Optics for TPS Storage Ring 4581
 
  • M.-S. Chiu, H.-P. Chang, H.C. Chao, C.-C. Kuo, H.-J. Tsai, C.H. Yang
    NSRRC, Hsinchu
 
 

To evaluate the feasibility for installing two insertion devices in the long straight sections (12 m long) of the TPS storage ring, two different kinds of the double mini-betay optics (symmetric and asymmetric configurations) were proposed to fulfill this purpose. In the symmetric case a quadrupole triplet is located at the center of the long straight, while in the asymmetric case a quadrupole doublet is used. The effects on the beam dynamics, such as the dynamic aperture, injection efficiency, and lifetime, etc., are presented.

 
THPE031 MATLAB-based Accelerator Physics Applications for the TPS Commissioning and Operation at NSRRC 4584
 
  • F.H. Tseng, H.-P. Chang, J. Chen, P.C. Chiu, K.T. Hsu, C.-C. Kuo, H.-J. Tsai
    NSRRC, Hsinchu
 
 

Taiwan Photon Source (TPS) is the second synchrotron light source in Taiwan which is currently under construction at the NSRRC existing site. With a 3 GeV beam energy, low emittance, 24-DB structure in the storage ring, the TPS can generate higher brilliance and more abundant X-ray sources. TPS is in complementary to the overbooked 1.5 GeV Taiwan Light Source (TLS). The MATLAB-based accelerator physics application programs planned for the TPS commissioning and operation is a high-level software collection including the MML, AT, LOCO, etc., developed at ALS and SLAC. In this report, the testing results by employing this package to the Taiwan Light Source (TLS) are given and the simulations of the TPS virtual machine are also demonstrated.

 
THPE032 Calculation of Coupled Lattice Functions from Turn-by-turn Trajectory Data in Storage Rings 4587
 
  • A. Wolski, M. Korostelev, K.G. Panagiotidis
    The University of Liverpool, Liverpool
 
 

BPMs capable of high resolution turn-by-turn bunch position measurements are becoming increasingly widely used in electron storage rings. Analysis of the data from a set of such BPMs following the excitation of a coherent betatron oscillation can yield useful information for tuning the optics and improving machine performance. This approach to optics measurement has the benefits that the data collection is very fast, and analysis can be local, so that application is as easy for a large ring as for a small one. Here, we describe a technique for using turn-by-turn BPM data to determine lattice functions that describe the local coupling in a storage ring; this may be helpful, for example, for achieving low vertical emittance. We discuss the principles of the technique, give some examples, and discuss possible limitations arising from BPM gain and coupling errors.

 
THPE033 Beam Dynamics Studies for the First Muon Linac of the Neutrino Factory 4590
 
  • C. Bontoiu, M. Aslaninejad, J.K. Pozimski
    Imperial College of Science and Technology, Department of Physics, London
  • S.A. Bogacz
    JLAB, Newport News, Virginia
 
 

Within the Neutrino Factory Project the muon acceleration process involves a complex chain of accelerators including a (single-pass) linac, two recirculating linacs and an FFAG. The linac consists of RF cavities and iron shielded solenoids for transverse focusing and has been previously designed relying on idealized field models. However, to predict accurately the transport and acceleration of a high emittance 30 cm wide beam with 10 % energy spread requires detailed knowledge of fringe field distributions. This article presents results of the front-to-end tracking of the muon beam through numerically simulated realistic field distributions for the shielded solenoids and the RF fields. Real and phase space evolution of the beam has been studied along the linac and the results will be presented and discussed.

 
THPE034 A Non-Scaling FFAG Gantry Design for the PAMELA Project 4593
 
  • R.J.L. Fenning, A. Khan
    Brunel University, Middlesex
  • T.R. Edgecock
    STFC/RAL, Chilton, Didcot, Oxon
  • D.J. Kelliher, S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
 
 

A gantry is required for the PAMELA project using non-scaling Fixed Field Alternating Gradient (NS-FFAG) magnets. The NS-FFAG principle offers the possibility of a gantry much smaller, lighter and cheaper than conventional designs, with the added ability to accept a wide range of fast changing energies. This paper will build on previous work to investigate a design which could be used for the PAMELA project.

 
THPE036 Tune Measurement in Non Scaling FFAG EMMA with Model Independent Analysis 4596
 
  • Y. Giboudot
    Brunel University, Middlesex
  • I. Kirkman, A. Wolski
    The University of Liverpool, Liverpool
 
 

The Non Scaling Fixed Field Alternating Gradient (NS-FFAG) EMMA accelerator has a purely linear lattice and thus allows important tune variation. The crossing of resonances during acceleration is a key characteristic of the beam dynamics. An accurate measurement of the tune is therefore mandatory. However commonly used measurement techniques requires the beam to perform an important number of turns in the machine. Simulations have shown that fast decoherence of the beam requires the study of another measurement technique. The model independent analysis (MIA) has been investigated. The singular value decomposition (SVD) of a matrix composed of simulated BPMs reading of various bunches trajectories gives a description of the optics function at each Beam Position Monitor. Including misalignment errors and electronic noise, an accurate value of the tune has been derived from statistical treatment repeating this process few hundreds of time.


yoel.giboudot@stfc.ac.uk

 
THPE037 Low Alpha Operation of the Diamond Storage Ring 4599
 
  • I.P.S. Martin, G. Rehm, J. Rowland, C.A. Thomas
    Diamond, Oxfordshire
  • R. Bartolini, I.P.S. Martin
    JAI, Oxford
 
 

The Diamond storage ring has been operated in low alpha mode providing short-pulse radiation for pump-probe experiments and coherent radiation for THz/IR measurements. Two lattices have been implemented, with both capable of providing a variable alpha in the range ±2x10-5, down to minimum values well below 1x10-6. The second lattice additionally provides a low emittance of 4nm.rad, compared to 35nm.rad for the first lattice. An overview of operation in low alpha mode is given, along with first measurements of coherent emission at long wavelengths under a variety of conditions.

 
THPE038 Low-emittance Tuning Simulations for the ILC Damping Rings 4602
 
  • K.G. Panagiotidis, A. Wolski
    Cockcroft Institute, Warrington, Cheshire
  • M. Korostelev, K.G. Panagiotidis
    The University of Liverpool, Liverpool
 
 

One of the major challenges for the International Linear Collider (ILC) damping rings is the attainment of the 2 pm vertical emittance specification. To achieve such an ultra-low vertical emittance a highly effective diagnostics and correction system is needed. However, since both BPMs and correctors have also negative impacts on the design (cost, complexity, impedance), it is important to understand how the number and locations of both these components affect the correction. In this paper we present the results of simulations for the Technical Design Phase baseline damping rings lattice (DCO4), aimed at understanding the effectiveness of orbit, dispersion, and coupling correction for different design and operation scenarios.

 
THPE039 Optimization of dipole-field profiles for emittance reduction in storage rings 4605
 
  • C.-x. Wang, Y. Wang
    ANL, Argonne
  • Y.M. Peng
    IHEP Beijing, Beijing
 
 

Nonuniform dipoles with bending field variation have been studied for reducing storage ring emittance in recent years. According to a new minimum emittance theory, the effects of an arbitrary dipole can be characterized by two parameters. To have a better idea of the potentials of nonuniform dipoles, here we numerically explore the values of these two parameters for optimal emittance reduction.

 
THPE040 A Spin Rotator for the Compact Linear Collider 4608
 
  • A. Latina, N. Solyak
    Fermilab, Batavia
  • D. Schulte
    CERN, Geneva
 
 

Polarized positron and electron beams are ideal for searching for new physics at the Compact Linear Collider (CLIC). In order to properly orient and preserve the polarization of the beam at the interaction point, the beam polarization must be manipulated by a spin rotator along the beam line. In this paper a spin rotator design for the CLIC is presented and its integration into the CLIC ring to main linac transport system is discussed.

 
THPE042 Single-stage Bunch Compressor for ILC-SB2009 4611
 
  • A. Latina, N. Solyak
    Fermilab, Batavia
 
 

The Project Management Design Team of the International Linear Collider has recently proposed fundamental changes to the published ILC RDR baseline with the goal of presenting a potential alternate design providing a more cost-effective solution. In this framework a new lattice for the Damping Rings has been presented, shortening the exit bunch length from the RDR value of 9 mm down to 6 mm. The shorter bunch length allowed the adoption of a simpler single-stage bunch compressor, instead of the RDR two-stage compressor. The new single-stage compressor has a compression ratio of 20 and still achieves the nominal RDR value of 0.3 mm bunch length at the Interaction Point. The new design has been optimized to generate the required compression while having a small SR emittance growth, and reduced energy spread. The new lattice and its optimization procedure are presented in this paper.

 
THPE043 Demonstration of Transverse-to-longitudinal Emittance Exchange at the Fermilab Photoinjector 4614
 
  • A.S. Johnson, H.T. Edwards, T.W. Koeth, A.H. Lumpkin, P. Piot, J. Ruan, J.K. Santucci, Y.-E. Sun, R. Thurman-Keup
    Fermilab, Batavia
 
 

Phase space manipulation techniques within two degrees of freedom are foreseen to enhance the performances of next generation accelerators such as high-energy physics colliders and accelerator based light sources. At the Fermilab A0 photoinjector, a proof-of-principle experiment to demonstrate the exchange of the transverse and longitudinal emittances is ongoing. The emittance exchange beamline consists of a 3.9 GHz normal conducting deflecting mode cavity flanked by two doglegs. Electron bunches with charges of 250 pC and energy of 14.3 MeV are routinely sent through the exchanger. In this paper, we report our latest results on the demonstration of emittance exchange obtained with significantly improved beam diagnostics. We also compare our experimental results with a simple numerical model.

 
THPE044 Design of Injection and Extraction Beamlines for the ALPHA Project 4617
 
  • Y.C. Jing, Y. Kim, S.-Y. Lee
    IUCF, Bloomington, Indiana
 
 

The Advanced eLectron-PHoton fAcility (ALPHA) is under construction to support Crane Naval Center's radiation effect testing program. This paper reports the design of injection and extraction beamlines for the ALPHA and discusses the nonlinear beam spreader which is used to convert transverse Gaussian beam distribution into uniform rectangular beam distribution.

 
THPE046 CesrTA Low Emittance Tuning 4620
 
  • J.P. Shanks, D. L. Rubin, D. Sagan
    CLASSE, Ithaca, New York
 
 

We are developing techniques for measuring and correcting emittance diluting optical and alignment errors in the CesrTA storage ring. Our principle measurement method is to resonantly excite the beam at all three normal mode frequencies and then to extract the amplitude and phase of each mode at all 100 beam position monitors. We reconstruct beta-functions, betatron phase advance, coupling parameters, dispersion, and BPM tilts from the data. A complete characterization including data collection and analysis can be done in a few minutes. To measure the emittance, an x-ray beam size monitor capable of measuring the size of a single bunch on a turn by turn basis provides a real time measure with a resolution on the order of a few microns. This resolution corresponds to a few pm emittance. Our ability to identify alignment and optical errors is limited by systematic measurement errors. We report on the status of our efforts to understand and eliminate systematic errors, the accuracy of our characterization of the machine optics, and our success at reducing sources of emittance dilution.

 
THPE047 Lattice Calibration with Turn-by-turn BPM Data 4623
 
  • X. Huang, J.J. Sebek
    SLAC, Menlo Park, California
 
 

Turn-by-turn beam position monitor (BPM) data from multiple BPMs are fitted with a tracking code to calibrate magnet strengths in similar manner as the well known LOCO code. Simulation shows that this method can be a quick and efficient way for optics calibration. The method is applicable to both linacs and ring accelerators. We also show experimental measurement of the transfer matrix with turn by turn BPM data.

 
THPE048 Lattice Modeling for SPEAR3 4626
 
  • X. Huang, J.A. Safranek
    SLAC, Menlo Park, California
 
 

We use measured or simulated magnetic fields for dipoles and quadrupoles to build a lattice model for SPEAR3. In a non-symplectic approach the phase space coordinate mapping on the fields is based on Runge-Kutta integration of the equation of motion. In a symplectic approach we approximate the fields with proper fringe field models. Complication of the use of rectangular gradient dipoles in SPEAR3 is considered. Results of the model is compared to measurements on the real machine.

 
THPE050 Real Beam Line Optics from a Synthetic Beam 4629
 
  • R.M. Bodenstein, Y. Roblin, M.G. Tiefenback
    JLAB, Newport News, Virginia
 
 

The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab can be described as a series of concatenated beamlines. Methods used to measure the Twiss parameters in closed orbit machines are not applicable in such open ended systems. We are using properly selected sets of real orbits in the accelerator, as one would for numerical analysis. The evolution of these trajectories along the beamline models the behavior of a synthetic beam which deterministically supplements beam profile-based Twiss parameter measurements and optimizes the efficiency of beamline tuning. Examples will be presented alongside a description of the process.

 
THPE051 Magnet Optical and Beam Matching Issues in a Medium Energy Beam Transport line of SNS Linac 4632
 
  • J. G. Wang, Y. Zhang
    ORNL, Oak Ridge, Tennessee
 
 

A Medium Energy Beam Transport line (MEBT) is employed in the SNS linac to match the beam from an RFQ to a DTL and to perform other functions. The MEBT lattice consists of fourteen electromagnetic quadrupoles. The quads have very small aspect ratios (steel length over aperture diameter), and they are densely packed in the lattice. Significant fringe fields and magnetic interference cause difficulties in beam matching. We have performed 3D simulations of the magnets, computed their optical properties, and compared their performance with what predicted by simple hard edge models. This paper reports our findings and possible solutions to the problem.

 
THPE052 Advanced Numerical Modeling of Collective Final Focus for Intense Ion Beams 4635
 
  • M. Dorf, R.C. Davidson, I. Kaganovich, E. Startsev
    PPPL, Princeton, New Jersey
 
 

This paper presents results of advanced numerical simulations demonstrating the feasibility of tight collective focusing of intense ion beams for the Neutralizing Drift Compression Experiment (NDCX-I). In the collective focusing scheme, a weak magnetic lens provides strong focusing of an intense ion beam carrying an equal amount of neutralizing electron background [S. Roberston, Phys. Rev. Lett. 48, 149 (1982)]. For instance, a solenoidal magnetic field of several hundred gauss can focus an intense neutralized ion beam within a short distance of several centimeters. The enhanced focusing is provided by a strong self-electric field, which is produced by the collective electron dynamics. The numerical simulations are performed with the LSP particle-in-cell (PIC) code, and the results of the simulations are found to be in good agreement with analytical predictions. Collective focusing limitations due to possible heating of the co-moving electrons during the transverse compression are also discussed.

 
THPE053 Linear and Chromatic Optics Measurements at RHIC 4638
 
  • R. Calaga
    BNL, Upton, Long Island, New York
  • M. Aiba
    PSI-LRF, Villigen, PSI
  • R. Tomás, G. Vanbavinckhove
    CERN, Geneva
 
 

Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and comparison to the optics model are presented.

 
THPE054 Spin Tune Dependence on Closed Orbit in RHIC 4641
 
  • V. Ptitsyn, M. Bai, T. Roser
    BNL, Upton, Long Island, New York
 
 

Polarized proton beams are accelerated in RHIC to 250 GeV energy with the help of Siberian Snakes. The pair of Siberian Snakes in each RHIC ring holds the design spin tune at 1/2 to avoid polarization loss during acceleration. However, in the presence of closed orbit errors, the actual spin tune can be shifted from the exact 1/2 value. It leads to corresponding shift of locations of higher-order ("Snake") resonances and limits available betatron tune space. The largest closed orbit effect on the spin tune comes from the horizontal orbit angle between the two snakes. During RHIC Run in 2009 dedicated measurements with polarized proton beams were taken to verify the dependence of the spin tune on the local orbits at the Snakes. The experimental results are presented along with the comparison with analytical predictions.

 
THPE055 Linear Optics Measurements and Corrections Using AC Dipole In RHIC 4644
 
  • G. Wang, M. Bai, L. Yang
    BNL, Upton, Long Island, New York
 
 

We report recent experimental results on linear optics measurements and corrections using ac dipole. In RHIC 2009 run, the concept of the SVD correction algorithm is tested at injection energy for both identifying the artificial gradient errors and correcting it using the trim quadrupoles. The measured phase beatings were reduced by 30% and 40% respectively for two dedicated experiments. In RHIC 2010 run, ac dipole is used to measure beta* and chromatic beta function. For the 0.65m beta* lattice, we observed a factor of 3 discrepancy between model and measured chromatic function in the yellow ring.

 
THPE056 A Method of Beam Energy Spread and Synchrotron Tune Mesurment Based on Decoherence Signal Analysis 4647
 
  • A. Sargsyan, K. Manukyan
    CANDLE, Yerevan
 
 

A method of beam energy spread and synchrotron tune measurements based on the analysis of transverse decoherence\recoherence signal of kicked beam is presented. As an illustration the beam energy spread was extracted for the SLS storage ring.

 
THPE060 A Compact Ring for the ThomX-ray Source 4650
 
  • A. Loulergue
    SOLEIL, Gif-sur-Yvette
  • C. Bruni, J. Haissinski, M. Joré, M. Lacroix, A. Variola
    LAL, Orsay
 
 

One advantage of X-ray sources based on Compton Back Scattering (CBS) processes is that such compact machines can produce an intense flux of monochromatic X-rays. CBS results from collisions between laser pulses and relativistic electron bunches. Aiming at high X-ray flux, one possible configuration combining a low emittance linear accelerator with a compact storage ring and a high gain laser cavity has been adopted by the ThomX project. We present here the main ring lattice characteristics in terms of baseline optics, possible other tunings such as low or negative momentum compaction, and orbit correction schemes. In addition, non-linear beam dynamics aspects including fringe field components as well as higher multipole tolerances are presented.

 
THPE061 Non Linear Beam Dynamics Studies at SOLEIL using Experimental Frequency Map Analysis 4653
 
  • P. Brunelle, A. Loulergue, A. Nadji, L.S. Nadolski, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
 
 

SOLEIL, the French 2.75 GeV high brilliance third generation synchrotron light source is delivering photons to 20 beam lines and is presently equipped with 17 insertion devices. Significant reduction of injection efficiency and beam lifetime are observed when using some undulator configurations in daily operation. Measurements on electron beam, such as beam lifetime versus RF voltage, have shown that the energy acceptance is strongly reduced by the combined non linear effects of the four U20 in-vacuum undulators and the HU640 10m long undulator used in linear vertical polarization mode. This paper will present the on and off momentum frequency map measurements that have been performed in order to investigate such effects. The reduction of the on momentum dynamic aperture in the presence of the U20 undulators is confirmed. The off momentum frequency map measurements confirm that the energy acceptance of the bare machine is very large as predicted by tracking calculations, and clearly exhibit the strong energy acceptance reduction due to undulators.

 
THPE062 Tilted Sextupoles for Correction of Chromatic Aberrations in Beam Lines with Horizontal and Vertical Dispersions 4656
 
  • N. Golubeva, V. Balandin, W. Decking
    DESY, Hamburg
 
 

We consider a beam line, in which pure betatron oscillations are transversely uncoupled, but which has nonzero horizontal and vertical dispersions simultaneously. We show that transverse oscillations in such a beam line could be chromatically coupled if the horizontal dispersion is nonzero in the vertical bending magnets and vice versa. We also show that the ability of sextupoles to generate chromatic coupling terms depends on the relation between sextupole tilt angles and the direction of the dispersion vector at the sextupole locations. We discuss different approaches to the setup of sextupole tilt angles depending on chromatic aberrations taken for correction. As a practical application we consider the usage of tilted sextupoles in the design of the beam switchyard at the European XFEL Facility.

 
THPE063 Investigation and Optimization of Transverse Non-linear Beam Dynamics in the High-energy Storage Ring HESR 4659
 
  • D.M. Welsch, A. Lehrach, B. Lorentz, R. Maier, D. Prasuhn, R. Tölle
    FZJ, Jülich
 
 

The High-Energy Storage Ring (HESR) is part of the upcoming Facility for Antiproton and Ion Research (FAIR). The HESR will provide antiprotons in the momentum range from 1.5 to 15 GeV/c for the internal target experiment PANDA. The demanding requirements of PANDA in terms of beam quality and luminosity together with a limited production rate of antiprotons call for a long beam life time and a minimum of beam loss. Thus, a sufficiently large dynamic aperture of the HESR is crucial. To provide this, a chromaticity correction scheme for the HESR has been developed to reduce tune spread and thus to minimize the emittance growth caused by betatron resonances. The chromaticity correction scheme has been optimized through dynamic aperture calculations. The estimated field errors of the HESR dipole and quadrupole magnets have been included in the non-linear beam dynamics studies. The ion optical settings of the HESR have been improved using dynamic aperture calculations and frequency map analysis technique. In this presentation comprehensive beam simulations are presented and predictions of long-term stability based on short-term particle tracking and orbit diffusion discussed.

 
THPE064 Electron Beam Dynamics in CERN-PSI-ELETTRA 5π/6 Traveling Wave X-band Linear Accelerator. 4662
 
  • M.M. El-Ashmawy, G. D'Auria, S. Di Mitri
    ELETTRA, Basovizza
 
 

The 4th Generation Light Source FERMI@ELETTRA, in construction at the ELETTRA Laboratory in Trieste, requires very short electron bunches at the entrance of the undulator chain. To linearize the longitudinal phase space in the presence of the compression process, a 4th harmonic decelerating section (11992 MHz) will be installed before the first magnetic chicane. An X-band structure, with integrated alignment monitors [1], is currently under development in the framework of collaboration between CERN-PSI-ELETTRA. In this paper we will present a full longitudinal and transversal beam dynamics of the electron beam along the X-band structure during linearization process using 3D space charge code TStep [2]. Beam dynamics simulations will also be continued along the whole FERMI linac using elegant code [3].

 
THPE065 Multipoles Minimization in the DAΦNE Wigglers 4665
 
  • S. Bettoni
    CERN, Geneva
  • B. Bolli, S. Ceravolo, S. Guiducci, F. Iungo, M.A. Preger, P. Raimondi, C. Sanelli, F.M. Sardone
    INFN/LNF, Frascati (Roma)
 
 

The wigglers of the DAΦNE main rings have been one of the main sources of the non-linearities in the collider. A method to minimize the odd integrated multipoles around the beam trajectory (the even ones tend to vanish due to the periodicity of the device) is described. It consists in displacing the magnetic axis of each pole towards the position of the beam in such a way that the integrated odd multipoles are minimized in each half period of the wiggler. After a study, including multipolar and tracking analysis, has performed to determine the best position of the axes, the wigglers in the DAΦNE main rings have been modified accordingly. To validate this approach magnetic measurements and tests with beam by means of closed orbit bumps have been performed.

 
THPE066 Simulation Study on Coherent Resonant Instability of Non-neutral Plasmas Confined in a Linear Paul Trap 4668
 
  • H. Sugimoto, K. Ito, H. Okamoto
    HU/AdSM, Higashi-Hiroshima
  • S.M. Lund
    LLNL, Livermore, California
 
 

Resonant instabilities of ion plasmas confined in a linear Paul trap are studied using the particle-in-cell code WARP. Transverse two-dimensional model is employed to save computing time and perform systematic investigations. Both applied and self-field forces are calculated with a boundary condition assuming a quadrupole electrode structure. A large number of simulations were carried out with rms matched plasmas to clarify characteristics of the instability caused by linear and nonlinear coherent resonances. Stop band distributions produced by the simulation runs are consistent with theoretical prediction. These results are also compared to experimental results obtained from Hiroshima University Paul trap that is developed to study beam dynamics. It is shown that the stop band distributions of both numerical and experimental results are good agreement each other. We confirmed from these results that coherent resonances are excited when one of the coherent tunes is close to a half integer.

 
THPE067 Dynamic Aperture Study at the SPring-8 Storage Ring 4671
 
  • M. Takao, J. Schimizu, Y. Shimosaki, K. Soutome
    JASRI/SPring-8, Hyogo-ken
 
 

The dynamic aperture is of importance for high injection efficiency and long lifetime of a storage ring. At the SPring-8 storage ring, a third generation light source facility, various improvements of the dynamic aperture were developed, e.g. the introduction of supplemental sextupole magnets at long straight sections, and the symmetry restoration of linear lattice. To understand the nonlinear dynamics limiting the aperture, the measurements were performed for the various operation conditions with the improvements. Using injection bump magnets and turn-by-turn beam position monitor system, we measured the horizontal dynamic aperture. The Fourier analysis of the oscillation of the kicked beam shows the resonance excitation influential on the dynamic aperture. The knowledge through the experiments is essential to the further improvements of the dynamic aperture of the present ring and the new storage ring design of the future SPring-8 upgrades.

 
THPE068 Effects of the Field Leakage of the Slow Extraction Septum Magnets of the J-PARC Main Ring 4674
 
  • A.Y. Molodozhentsev, T. Koseki, M. Tomizawa
    KEK, Ibaraki
  • A. Ando
    J-PARC, KEK & JAEA, Ibaraki-ken
 
 

During the early J-PARC Main Ring commissioning the emittance growth at the injection energy, caused by the field leakage of the slow extraction septums, has been observed. By using the measured field data in the J-PARC Main Ring computational model we perform the analysis of the resonance excitation for the 'bare' working points around the 3rd order horizontal resonance, used for the slow extraction of the accelerated beam. The space charge effects of the low energy beam with the moderate beam power are taken into this analysis. Some possible ways to reduce the transverse emittance dilution and the particle losses during the machine operation for the 'hadron' experiments are discussed.

 
THPE069 Simulation of Space Charge Effects in JPARC 4677
 
  • K. Ohmi, K. Fan, S. Igarashi, Y. Sato
    KEK, Ibaraki
  • H. Hotchi, Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

Nonlinear space charge interaction in high intensity proton rings causes beam loss, which limits the performance. Simulations based on particle in cell method has been performed for JPARC-Rapid Cycle Synchrotron and Main Ring. Beam loss estimation during acceleration and resonances analysis are discussed with various simulations using dynamic and frozen models.

 
THPE070 Synchro-beta Resonance Simulation using Measured Chromatic Aberrations 4680
 
  • Y. Seimiya, K. Ohmi
    KEK, Ibaraki
 
 

Synchro-beta resonances enhance beam sizes dynamically. For accelerators aimed for high luminosity, the effect can be more serious since a difference between vertical emittance and longitudinal emittance tends to be larger. Therefore, it is necessary to estimate a tune spread of the synchro-beta resonances properly. Synchro-beta effect is caused by chromatic aberrations, which characterize how optics parameters, including tune, Twiss parameter, X-Y coupling parameter, and other parameters, depend on the momentum deviation. The chromatic aberrations are actually defined by coefficients of an optics parameter in is expansion in terms of momentum deviation. The synchro-beta resonances caused by chromatic aberrations are discussed in this conference. We use 6-dimensional symplectic map which is obtained from measured optics parameters in order to simulate beam motion precisely*.


* Y. Seimiya and K. Ohmi, TH6PFP020, Particle Accelerator Conference PAC09, 4-8 May 2009, Vancouver, Canada.

 
THPE071 Space Charge Effect for Rotation of Longitudinal Phase Space in Alpha Magnet 4683
 
  • H. Hama
    Tohoku University, School of Scinece, Sendai
  • N.Y. Huang
    NTHU, Hsinchu
 
 

In compact linac system, alpha magnet seems to be a useful device to manipulate the longitudinal phase space. Particularly combined use with thermionic RF gun has been regarded as a convenient system for bunch compression. The alpha magnet simply acts to rotate the longitudinal phase space of the beam, besides energy selection by an aperture in it. However, by using the alpha magnet, if we like to produce high brilliant electron beam with considerable charge, space charge force has to be carefully taken into account to evaluate the beam property for not only the longitudinal but also the transverse. Since the both transverse motions and the longitudinal one are coupled with each other in the alpha magnet, it is mostly impossible to evaluate the space charge effect analytically. Meanwhile, because energies of the electrons from the thermionic RF gun are ranging from zero to the maximum, a conventional way to count Coulomb force in the rest frame may be not satisfactorily valid in numerical simulations. We will discuss space charge dominated phase spaces derived from 3-D tracking simulations* for the alpha magnet. *GPT (General Particle Tracer) and an FDTD code developed ourselves.

 
THPE073 Experimental Study of Spurious Mode in the PLS and PLS-II Storage Ring Vacuum Chamber 4686
 
  • Y.D. Joo, T. Ha, C. Kim, C.D. Park, S.J. Park
    PAL, Pohang, Kyungbuk
 
 

A superconducting RF cavity is used in the storage ring of the Pohang Light Source (PLS) upgrade project (PLS-II) at Pohang Accelerator Laboratory (PAL) for increasing the electron beam current and energy from 2.5GeV/200mA to 3.0GeV/400mA. In order to meet the requirement of lower beam emittance and higher photon energies, as well as more straight sections for insertion devices, the vacuum chambers in the storage ring need to be reconstructed. To control the spurious harmonic resonances' effect to beam position monitors (BPMs) in the PLS and PLS-II storage ring vacuum chamber, the TE mode distribution in vacuum chambers has been analyzed by both numerical simulation and experiment. Based on this analysis, the proper method to control the strength of TE mode at the position of BPMs is suggested.

 
THPE074 Beam Envelope Control in Heavy Ion Superconducting Drift Tube Linac 4689
 
  • V.S. Dyubkov, S.M. Polozov, A.V. Samoshin
    MEPhI, Moscow
 
 

At present a number of high energy heavy ion linear accelerator projects are discussed. FRIB accelerator is under R&D in Michigan University in USA, GANIL in France etc. The RIA (AEBF) project was designed in ANL, USA some years ago*. The linac should consist of a number of ion sources, matching system, pre-buncher and high energy sections. Using of independently phased short SC resonators with drift tubes is possible for beam acceleration and SC solenoids or quadruple can be used for focusing. The alternative phase focusing can be also useful**. The beam envelope control is one of the main problems in this linac. The method of analytically beam dynamics investigation will be discussed in the future report. The conditions of beam envelope control will be carried out by using of especially averaging method, discussed in*** initially.


* P.N.Ostroumov et al., Proc. of PAC01, p.4080
** E.S.Masunov, A.V.Samoshin, Proc. of PAC07, p.1568
*** V.S.Dyubkov, E.S.Masunov, Probl. of Atom. Sci.&Tech., Ser. Nucl. Phys. Investig. (in press)

 
THPE075 Application of Frequency Map Analysis to Beam-Beam Effects Study in Crab Waist Collision Scheme 4692
 
  • E.A. Simonov, E.B. Levichev, D.N. Shatilov
    BINP SB RAS, Novosibirsk
 
 

We applied Frequency Map Analysis (FMA) - a method that is widely used to explore dynamics of Hamiltonian systems - to beam-beam effects study. The method turned out to be rather informative and illustrative in case of a novel Crab Waist collision approach, when "crab" focusing of colliding beams results in significant suppression of betatron coupling resonances. Application of FMA provides visible information about all the working resonances, their widths and locations in the planes of betatron tunes and betatron amplitudes, so the process of resonances suppression due to the beams crabbing is clearly seen.

 
THPE076 Effect of the Phase One Insertion Devices in the ALBA Storage Ring 4695
 
  • Z. Martí, G. Benedetti, D. Einfeld, M. Muñoz
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès
 
 

The synchrotron light source ALBA incorporates 6 insertion devices (2 Apple-II type undulators, 2 plannar in-vacuum undulators, 1 normal conducting multipole wiggler and 1 superconduction multipole wiggler) at the start of operation. The effect of the different IDs in the performance of the facility is evaluated, using several methods (kick maps, hard edge models, dynamic multipoles, …), including a comparison of the agreement of the different models and simulation codes. According to the results, and due mainly to the influence of the superconducting wiggler, a new working point has been selected.

 
THPE077 Predicted Effect of the Measured High Order Magnetic Multipole in the ALBA Storage Ring 4698
 
  • M. Muñoz, G. Benedetti, D. Einfeld, Z. Martí
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès
 
 

The high order magnetic multipole components of all the magnets in the ALBA storage ring have been measured. Previous studies have simulated the effects of the HOMs using statistic methods. The magnets have been installed now in the tunnel, allowing for a better simulation of the future impact of the HOMs in the performance of the light source. In this paper, the effect of the high order multipoles of the dipole, quadrupole and sextupole magnets in the dynamic aperture and the Touschek lifetime are reviewed.

 
THPE078 Beam Dynamics Investigation of the 101.28 MHz IH Structure as Injector for the HIE-ISOLDE SC Linac 4701
 
  • M.A. Fraser, M. Pasini, D. Voulot
    CERN, Geneva
  • M.A. Fraser, R.M. Jones
    UMAN, Manchester
 
 

The first phase of the HIE-ISOLDE project at CERN consists of a superconducting (SC) linac upgrade in order to increase the energy of post-accelerated radioactive ion beams from 2.8 MeV/u to over 10 MeV/u (for A/q = 4.5). In preparation for the upgrade, we present beam dynamics studies of the booster section of the normal conducting (NC) REX-ISOLDE linac, focused on the longitudinal development of the beam in the 101.28 MHz IH cavity, employing a Combined Zero Degree Structure* (KONUS), pulsing at a high gradient of over 3 MV/m. The evolution of the transverse emittance in the superconducting linac depends critically on the injected phase space distribution of particles from the existing linac and, with a better understanding of the longitudinal beam dynamics upstream, the performance of the upgrade can be optimised. Data taken during the commissioning phase of the REX-ISOLDE linac is analysed to understand the properties of the beam in the booster and combined with beam dynamics simulations which include the realistic fields of the IH structure, determined from both simulation and perturbation measurement. The matching of the NC and SC machines is also discussed.


*Ratzinger, U., "The IH-structure and its capability to accelerate high current beams," Particle Accelerator Conference, 1991.

 
THPE079 Proposal of a Relationship between Dynamic Aperture and Intensity Evolution in a Storage Ring 4704
 
  • M. Giovannozzi
    CERN, Geneva
 
 

A scaling law for the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers, about ten years ago. The use of fundamental theorems of the theory of dynamical systems allowed showing that the dynamic aperture has a logarithmic dependence on time. In this paper this result, proven by mean of numerical simulations, is used as a basis for deriving a scaling law for the intensity evolution in a storage ring. The proposed scaling law is also tested against experimental data showing a remarkable agreement.

 
THPE080 Dynamic Aperture Computation for the as-built CERN Large Hadron Collider 4707
 
  • M. Giovannozzi
    CERN, Geneva
 
 

During the design phase of the CERN Large Hadron Collider the dynamic aperture, i.e., the domain in phase space where stable motion occurs, was used as figure-of-merit to specify the field quality of the various classes of superconducting magnets. The programme of magnetic measurements performed within the framework of the magnets' acceptance process has produced a large amount of information available, which can be used to estimate the value of the dynamic aperture for the actual machine. In this paper the results of massive numerical simulations based on the measured field quality, both for injection and top energy configurations, are presented and discussed in detail.

 
THPE081 First Results of Space Charge Simulations for the Novel Multi-turn Injection 4710
 
  • M. Giovannozzi, M. George
    CERN, Geneva
  • F. Franchi
    ESRF, Grenoble
 
 

Recently, a novel multi-turn injection technique was proposed. It is based on beam merging via resonance crossing. The various beamlets are successively injected and merged back by crossing a stable resonance generated by non-linear magnetic fields. Space charge is usually a crucial effect at injection in a circular machine and it could have an adverse impact on the phase space topology required for merging the various beamlets. Numerical simulations were performed to assess the stability of the merging process as a function of injected beam charge. The results are presented and discussed in this paper.

 
THPE082 Higher Order Mode Analysis of the SPL Cavities 4713
 
  • M. Schuh, F. Gerigk, J. Tuckmantel
    CERN, Geneva
  • M. Schuh
    MPI-K, Heidelberg
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire
 
 

Higher Order Modes (HOMs) can severely limit the operation of superconducting cavities in a linac with high beam current, high duty factor and complex pulse structure. The full HOM spectrum has to be analyzed in order to identify potentially dangerous modes already during the design phase and to define their damping requirements. For this purpose a dedicated beam simulation code focused on beam-HOM interaction was developed, taking into account important effects like the HOM frequency spread, beam input jitter, different chopping patterns, as well as klystron and alignment errors. Here this code is used to investigate in detail the HOM properties of the cavities foreseen in the Superconducting Proton Linac (SPL) at CERN and their potential to drive beam instabilities. A special focus is set to HOM excitation by chopped pulses with high repetition rate and on the influence of HOMs on recirculating electron beams in the high-energy part of the SPL. Finally, the HOM characteristics of similar linac designs are presented and compared to the SPL.

 
THPE083 Signal Quality of the LHC AC Dipoles and its Impact on Beam Dynamics 4716
 
  • R. Miyamoto
    BNL, Upton, Long Island, New York
  • M. Cattin, J. Serrano, R. Tomás
    CERN, Geneva
 
 

The adiabaticity of the AC dipole might be compromised by noise or unwanted frequency components in its signal. An effort has been put to characterize and optimize the signal quality of the LHC AC dipoles. The measured signal is used in realistic simulations in order to evaluate its impact on beam dynamics and to ultimately establish safe margins for the operation of the LHC AC dipoles.

 
THPE084 Impact of Filling Patterns in Bunch Length and Lifetime at the SLS 4719
 
  • N. Milas, L. Stingelin
    PSI, Villigen
 
 

The filling pattern can have a big impact in the effective bunch lengthening of a passive 3rd harmonic system and as a consequence in the Touschek component of the beam lifetime. Using a longitudinal dynamics tracking code, in which the effects of the accelerating system and the 3rd harmonic system are taken into account, we can calculate the synchronous phase drift caused by the transient beam-loading and thus the effective bunch increase for several different filling patterns. In this paper we present a comparison between simulation and measurements for the SLS.

 
THPE085 Applicability of Panofsky-Wenzel Theorem 4722
 
  • A. Opanasenko
    NSC/KIPT, Kharkov
 
 

In a 1956 article* Panofsky and Wenzel derived the relation for the net transverse kick experienced by a fast charge particle crossing a closed cavity excited in a single rf mode. Later on this relation, usually referred to the Panofsky-Wenzel theorem, was generalized for cavity containing wake field induced by a driving charge. This theorem has played very important role in the accelerator physics. One well-known conclusion of this paper was that in a TE mode the deflecting impulse of the electric field always cancels the impulse of the magnetic fields. In our presentation we more exactly rederive Panofsky and Wenzel's result and obtain correction terms to the transverse kick. We show that in a TE mode the net transverse kick does not zero but is determined by a ponderomotive force. Using the given approach we find correction terms to wake potentials which are inversely proportional to the relativistic factor. Practical implications of our results are discussed.


* W.K.H. Panofsky and W.A. Wenzel, Rev. Sci. Instrum. 27, 967 (1956).

 
THPE086 Non-Linear Parametric Effects and Beam Collapse at Motion of Accelerated Particles in Transversal Focusing Fields 4725
 
  • M.V. Vysotskyy, V.I. Vysotskii
    National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev
 
 

The new type of oriental motion, so called parametric channeling of accelerated charged particles with internal energy structure in crystals or transversal focusing fields (TFF) is studied [*,**]. Peculiarities of this motion are connected with parametric coupling of transversal oscillations of fast particle in TFF (e.g. averaged field of crystal plains) and oscillations caused by internal processes in particle. Parametric channeling is investigated for small charged mesomolecules, atomic ions and nuclei with internal resonances, relativistic electrons. It was shown that such parametric coupling leads to the possibility of beam cooling and "collapse": critical decrease of transversal oscillations of moving structured ion in TFF due to energy transfer from this ion to its own internal electron (for atomic ion) or its internal low energy nuclear state (for fast nuclei). Also it was shown that parametric beam cooling with the decrease of transversal energy can take place at axial relativistic electron beams channeling. This process is caused by the parametric coupling between quantized channeling states and electron spin states in effective magnetic field in moving system.


* M.V.Vysotskyy V.I.Vysotskii, N.V.Maksuyta. Journal of Surface Investigation, V.2, No 2 (2008) 245.
** V.I.Vysotskii, M.V.Vysotskyy. Journal of Surface Investigation, 2008, V.2, No 2 (2008), 253.

 
THPE087 Calibration of the Nonlinear Accelerator Model at Diamond Storage Ring 4728
 
  • R. Bartolini, G. Rehm, J. Rowland
    Diamond, Oxfordshire
  • P. Kuske
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
  • I.P.S. Martin
    JAI, Oxford
  • F. Schmidt
    CERN, Geneva
 
 

The correct implementation of the nonlinear ring model is crucial to achieve the top performance of a synchrotron light source. Several dynamics quantities can be used to compare the real machine with the model and eventually to correct the accelerator. Most of these methods are based on the analysis of turn-by-turn data of excited betatron oscillations. We present the experimental results of the campaign of measurements carried out at the Diamond. A combination of Frequency Map Analysis and resonant driving terms measurements has allowed a precise calibration of the nonlinear model capable of reproducing and then correcting the nonlinear beam dynamics in the storage ring.

 
THPE088 Beam Dynamics Effect of Insertion Devices at Diamond Storage Ring 4731
 
  • B. Singh, R.T. Fielder, J. Rowland
    Diamond, Oxfordshire
  • R. Bartolini, I.P.S. Martin
    JAI, Oxford
 
 

Diamond operates with 10 in-vacuum insertion devices at 5 mm gap, two Apple-II, two superconducting and two normal conducting wigglers. We report here the correction of the linear optics of wigglers and measurements of nonlinear effects such as dynamic aperture and frequency maps and their impacts on injection efficiency, lifetime and loss distribution in operation of the storage ring.

 
THPE089 Uses of Turn-by-turn Data from FPGA-based BPMs during Operation at the APS Storage Ring 4734
 
  • V. Sajaev
    ANL, Argonne
 
 

APS has started a program of upgrading old BPM electronics to new FPGA-based devices. We present here the use of such BPMs for online measurement of betatron tunes during topup operation. In topup injection, the stored beam is kicked and experiences betatron oscillations that can be used for online monitoring of the betatron tunes. Also, due to kicker waveform time dependence, different bunches experience kicks of different amplitude. By collecting data from different bunches one can also monitor tune shift with amplitude. In the case of APS, the matter is complicated by the very fast decoherence of oscillations. We describe methods used to derive tunes and present results of online monitoring.

 
THPE091 Simultaneous Measurement of all Sextupole Offsets using the Response Matrix Fit 4737
 
  • V. Sajaev, A. Xiao
    ANL, Argonne
 
 

APS linear model is defined by the quadrupole and skew quadrupole errors that are determined using the response matrix fit. What was missing until now were the sextupole offsets relative to the beam orbit. At APS the orbit is routinely steered according to user requests, and at some locations the steering has accumulated to rather large values. That is why the usual sextupole changes that are performed during operation mode switches lead to optics and coupling changes. Knowledge of the sextupole offsets would allow us to predict and control those changes. There are a number of ways to measure sextupole offsets but most of them utilize element by element approach. This would take very long time for the 280 sextupoles at APS. Here we describe a method that determines the beam offsets of all sextupoles based on fitted values of local optics and coupling changes at each sextupole. We perform response matrix measurement, fit several lattices with different sextupoles, and derive the sextupole offsets. The results are included in the linear model of the APS storage ring.

 
THPE093 CRAB Cavity in CERN SPS 4740
 
  • H.J. Kim, T. Sen
    Fermilab, Batavia
 
 

Beam collisions with a crossing angle at the interaction point are often necessary in colliders to reduce the effects of parasitic collisions which induce emittance growth and decrease beam lifetime. The crossing angle reduces the geometrical overlap of the beams and hence the luminosity. Crab cavity offer a promising way to compensate the crossing angle and to realize effective head-on collisions. Moreover, the crab crossing mitigates the synchro-betatron resonances due to the crossing angle. A crab cavity experiment in SPS is proposed as a proof of principle before deciding on a full crab-cavity implementation in the LHC. In this paper, we investigate the effects of a single crab cavity on beam dynamics in the SPS and life time.

 
THPE094 A Search for Integrable Four-dimensional Nonlinear Accelerator Lattices 4743
 
  • S. Nagaitsev
    Fermilab, Batavia
  • V.V. Danilov
    ORNL, Oak Ridge, Tennessee
 
 

Integrable nonlinear motion in accelerators has the potential to introduce a large betatron tune spread to suppress instabilities and to mitigate the effects of space charge and magnetic field errors. To create such an accelerator lattice one has to find magnetic and/or electrtic field combinations leading to a stable integrable motion. This paper presents families of lattices with one invariant where bounded motion can be easily created in large volumes of the phase space. In addition, it presents two examples of integrable nonlinear accelerator lattices, realizable with longitudinal-coordinate-dependent magnetic or electric fields with the stable nonlinear motion, which can be solved in terms of separable variables.

 
THPE095 Quantitative Lattice Optimization using Frequency Map Analysis 4746
 
  • C. Steier, W. Wan
    LBNL, Berkeley, California
 
 

Frequency Map Analysis has been used successfully to study accelerator lattices for many years, both in simulations and in experiment. We will present a new application to use the quantitative results of frequency maps (namely the diffusion rates) to optimize the nonlinear properties of lattices. The technique is fairly simple but powerful and has already been used to optimize lattices for example for the NLC and ILC damping rings, as well as the ALS lattice upgrade.

 
THPE097 Charged-Particle Dynamics in an Adiabatic Thermal Beam Equilibrium 4749
 
  • H. Wei, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
 
 

The dynamics of charged particles in a recently-discovered adiabatic thermal beam equilibrium* are studied. In particular, test particle motion is analyzed numerically, assuming the beam equilibrium fields are in a periodic solenoidal focusing channel. Poincare surface-of-section maps are generated to examine the behavior of the test particles in phase space such as nonlinear resonances and chaotic regions. Comparisons are made between the adiabatic thermal and rigid-rotor Vlasov beam equilibria**.


* J. Zhou, K.R. Samokhvalova, and C. Chen, Phys. Plasmas 15, 023102 (2008)
** C. Chen, R. Pakter and R.C. Davidson, Phys. Rev. Lett. 79, 225 (1997)

 
THPE099 RHIC Proton Beam Lifetime Increase with 10- and 12-pole Correctors 4752
 
  • W. Fischer, J. Beebe-Wang, Y. Luo, S. Nemesure
    BNL, Upton, Long Island, New York
  • L.K. Rajulapati
    SBU, Stony Brook, New York
 
 

The RHIC beam lifetime in polarized proton operation is dominated by the beam-beam effect, parameter modulations, and nonlinear magnet errors in the interaction region magnets. Sextupole and skew sextupole errors have been corrected deterministically for a number of years based on tune shift measurements with orbit bumps in the triplets. During the most recent polarized proton run 10- and 12-pole correctors were set through an iterative procedure, and used for the first time operationally in one of the beams. We report on the procedure to set these high-order multipole correctors and estimate their effect on the integrated luminosity.

 
THPE100 Bunch Length Effects in the Beam-beam Compensation with an Electron Lens 4755
 
  • W. Fischer, Y. Luo, C. Montag
    BNL, Upton, Long Island, New York
 
 

Electron lenses for the head-on beam-beam compensation are under construction at the Relativistic Heavy Ion Collider. The bunch length is of the same order as the beta-function at the interaction point, and a proton passing through another proton bunch experiences a substantial phase shift which modifies the beam-beam interaction. We review the effect of the bunch length in the single pass beam-beam interaction, apply the same analysis to a proton passing through a long electron lens, and study the single pass beam-beam compensation with long bunches.

 
THPE102 6-D Weak-strong Simulation of Head-on Beam-beam Compensation in the RHIC 4758
 
  • Y. Luo, W. Fischer
    BNL, Upton, Long Island, New York
 
 

An electron lens was proposed to compensate the head-on beam-beam effect for polarized proton operations in the Relativistic Heady Ion Collider (RHIC). With head-on beam-beam compensation, we plan to reduce the beam-beam tune footprint and increase the beam-beam parameter to increase the luminosity. Here we carry out 6-D weak-strong beam-beam simulations to study the stability of proton particles and the proton beam lifetime in the presence of head-on beam-beam compensation. The effects and tolerances of the errors and noises in the compensation are also calculated.

 
THPE103 Sorting Chromatic Sectupoles for Second Order Chromaticity Correction in the RHIC 4761
 
  • Y. Luo, W. Fischer, G. Robert-Demolaize, S. Tepikian, D. Trbojevic
    BNL, Upton, Long Island, New York
 
 

In this article, based on the contributions of the chromatic sextupole families to the half-integer resonance driving terms, we discuss how to sort the chromatic sextupoles in the arcs of the Relativistic Heavy Ion Collider (RHIC) to easily and effectively correct the second order chromaticities. We propose an online method with 4 knobs or 4 pairs of chromatic sextupole families to correct second order chromaticities. Numerical simulations support this method and shows that it improves the balance of correction strengths among the sextupole families and avoids reversal of sextupole polarities, as well as yielding larger dynamic apertures for the 2009 RHIC 100 GeV polarized proton run.