| Paper | Title | Other Keywords | Page | ||
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| MOPA009 | Global Decoupling on the RHIC Ramp | coupling, quadrupole, betatron, injection | 659 | ||
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Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886. |
The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). In the polarized proton run, the betatron tunes are required to keep almost constant on the ramp to avoid spin resonance line crossing and the beam polarization loss. Some possible correction schemes on the ramp, like three-ramp correction, the coupling amplitude modulation and the coupling phase modulaxtion, have been found. The principles of these schemes are shortly reviewed and compared. Operational results of their applications on the RHIC ramps are given. |
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| MPPE009 | 2003-2004 Nonlinear Optics Measurements and Modeling for the CERN SPS | dipole, simulation, multipole, quadrupole | 1171 | ||
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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.
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| MPPE012 | MAD-X PTC Integration | lattice, radiation, synchrotron, synchrotron-radiation | 1272 | ||
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MAD-X is CERN's successor for MAD8, a program for accelerator design with a long history. MAD-X is a modular, better maintainable re-write of MAD8 with data structures written in C. Early on in the design of MAD-X we relied on the fact that older or doubtful modules could be replaced by new modules using the PTC code by E. Forest. Both codes remain independent entities but are linked via a converter to the MAD-X data structures. PTC is used for symplectic tracking of smaller machines and transfer line using better defined physical models of the elements and taking into account of how the elements are placed in the tunnel. The matching of the LHC will profit form the fact that the high order nonlinear parameters are provided by a PTC Normal Form analysis.
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| MPPE020 | Control of Dynamic Aperture for Synchrotron Light Sources | sextupole, radiation, emittance, lattice | 1670 | ||
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Funding: Under Contract with the U.S. Department of Energy Contract Number DE-AC02-98CH10886. |
Given the following frameworks: "A Hamiltonian-Free Description of Single Particle Dynamics for Hopelessly Complex Periodic Systems" (Forest, 1990), "Normal Form Methods for Complicated Periodic Systems" (Forest, Berz, Irwin, 1989), "The Correct Local Description for Tracking in Rings" (Forest, 1994), "The C++ Programming Language" (Stroustrup, 1985), we have designed a compact object oriented beam dynamics class by re-using existing FORTRAN libraries for: Truncated Power Series Algebra (Berz, SSC, 1988), and Map Normal Rorm (Forest, CBP, LBNL, 1990). In other words, implemented a numerical- and analytical model for: 6-dim phase space tracking, with classical radiation, and evaluation of equilibrium emittance, driving terms, amplitude dependent tune shifts, chromaticity, momentum compaction, etc., to arbitrary order, with self-consistent treatment of magnet errors. The tool was developed for the lattice design of NSLS-II. |
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| MPPE040 | Efficient Modeling of Nonlinear Beam Optics Using Parametric Model Independent Analysis | simulation, lattice, quadrupole, beam-transport | |||
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Funding: Research supported by DOE grant number: DE-FG02-04ER86225. |
Based on precision beam orbit measurements, Model Independent Analysis(MIA) has been used successfully to build a computer model that matches the linear optics of the real accelerator. We report a parametric extension of MIA that will allow efficient modeling of the nonlinear beam optics to account for energy dispersions. A simulation study is presented where the nonlinear dependency of lattice parameters on beam energy is captured by constrained training of a universal nonlinear approximator. These parametric nonlinear models of beam optics are easy to construct, diagnose, and modify. They can be very useful for more accurate model predicted beam operation and control. |
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| MPPE047 | Optics Flexibility and Matching at LHC Injection | injection, quadrupole, alignment, emittance | 2983 | ||
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An excellent match between the SPS, the several kilometers long transfer lines and the LHC will be required to minimise emittance blow-up at injection. Several optics changes in the SPS and the LHC injection insertions had to be accommodated in the design phase. The new 3-phase collimation system in the transfer lines results in additional phase advance constraints. It will be important to maintain some tuning range for the LHC commissioning phase and to accommodate possible further optics changes. We analyse the requirements, the constraints, the current status and options to enhance the optics flexibility.
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| MPPE049 | Sensitivity Study for Evaluating the Extracted Beam Parameters of the LLUMC Proton Therapy Synchrotron | emittance, proton, synchrotron, target | 3046 | ||
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The MINOS nonlinear constrained optimization program, working in concert with the beam optics code TRANSPORT, has been shown in recent work to provide a fast, efficient and reliable procedure for determining the parameters of the beam extracted from the LLUMC proton therapy synchrotron. MINOS and TRANSPORT work together as Modules of the Particle Beam Optics Laboratory (PBO Lab) software. The software was used to determine the parameters of the beam extracted from the synchrotron accelerator that best fit the extensive wire scanner profile data used to monitor the LLUMC proton therapy beamlines. In this paper additional constraints and optimizer variables are utilized with the procedure, in order to evaluate the sensitivity of the best fit extracted beam parameters to various assumptions. The methods used will be described and selected results from the study presented.
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| MPPE058 | Virtual Accelerator for Accelerator Optics Improvement | coupling, quadrupole, lattice, luminosity | 3426 | ||
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Funding: Work supported by Department of Energy contract DE-AC02-76SF00515. |
Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling eigen-plane ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and linear coupling reduction to improve PEP-II luminosity. |
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| MPPE059 | Precision Measurement of Coupling Ellipses Parameters in a Storage Ring | coupling, lattice, resonance, storage-ring | 3459 | ||
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Funding: Work supported by Department of Energy contract DE-AC02-76SF00515. |
Eigen-mode coupling ellipses' tilt angles and axis ratios can be precisely measured with a Model-Independent Analysis (MIA) of the turn-by-turn BPM data from resonance excitation of the betatron motion. For each BPM location one can measure 4 parameters from the two resonance excitation, which completely describe the linear coupling of the location. Results from application to PEP-II storage rings are presented. |
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| MPPE060 | Quadrupole Beam-Based Alignment at RHIC | quadrupole, injection, alignment, heavy-ion | 3493 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy |
Successful implementation of a beam-based alignment algorithm, tailored to different types of quadrupoles at RHIC, provides significant benefits to machine operations for heavy ions and polarized protons. This algorithm is used to calibrate BPM centers relative to interaction region (IR) quadrupoles to maximize aperture. It is also used to determine the optimal orbit through transition jump quadrupoles to minimize orbit changes during the transition jump for heavy ion acceleration. This paper provides background discussion and results from first application during the RHIC 2005 run. |
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| MPPE061 | Measurement and Correction of Nonlinear Chromaticity in RHIC | octupole, insertion, luminosity, sextupole | 3523 | ||
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Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy. |
To improve luminosity in RHIC by using smaller Beta,* higher order chromatic effects may need to be corrected. Measuring of higher order chromaticities is discussed and compared to a model of RHIC, showing good agreement. Assuming round beams, four families of octupoles are used to correct the second order chromaticities while keeping under control the amplitude dependent betatron tune spread in the beams. We show that the octupoles can reduce the second order chromaticity in RHIC, but they have insufficient strength for complete correction. |
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| MPPE065 | Fully Coupled Analysis of Orbit Response Matrices at the FNAL Tevatron | quadrupole, coupling, storage-ring, luminosity | 3662 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38, and by the Universities Research Association, Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy. |
Optics measurements have played an important role in improving the performance of the FNAL Tevatron collider. Initial optics measurements were performed using a small number of differential orbits, which allowed us to carry out the first round of optics corrections. However, because of insufficient accuracy, it was decided to apply the response matrix analysis method for further optics improvements. The response matrix program developed at ANL has been expanded to include coupling – the essential feature required to describe the Tevatron optics. The results of the optics calibration are presented and compared to local beta function measurements. |
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| MPPE076 | Design Study on a New Separator for PEEM3 | electron, quadrupole, focusing, dipole | 3985 | ||
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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. |
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| MPPP004 | LHC Orbit Stablisation Tests at the SPS | feedback, ground-motion, quadrupole, collimation | 886 | ||
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The LHC presently build at CERN is the first proton collider that requires a continuous orbit control for safe and reliable machine operation. A realistic test of the orbit feedback system has been performed in 2004 using already present LHC instrumentation and infrastructure on a 270 GeV coasting beam in the SPS. It has been demonstrated that the chosen feedback architecture can stabilise the beam better than 10 micrometre and is essentially limited by the noise of the beam position monitor and the bandwidth of the corrector magnets. The achieved orbit stability is comparable to those found at modern light sources and gives enough operational margin with respect to the requirements of the LHC Cleaning System (70 micrometre). Estimates for the long term drifts and achievable stability will be presented based on the experimental results.
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| MPPP013 | Stabilizing Low Frequency Beam Motion in the Tevatron | damping, quadrupole, feedback, resonance | 1353 | ||
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Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy. |
A feed back orbit stabilization system has been developed using a set of BPMS and existing Tevatron corrector magnets to stabilize beam motion up to 50 microns below 25 Hz. The construction of this system is described and the stability limits and magnitude of beam motion reduction is explored. |
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| MPPT049 | Optimization of Open Midplane Dipole Design for LHC IR Upgrade | dipole, luminosity, radiation, quadrupole | 3055 | ||
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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. |
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| TOAC004 | Experimental Investigation of Beam Breakup in the Jefferson Laboratory 10 kW FEL Upgrade Driver | damping, simulation, recirculation, quadrupole | 369 | ||
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Funding: This work supported by the Office of Naval Research, the Joint Technology Office, the Commonwealth of Virginia, the Air Force Research Laboratory, Cornell University and by DOE Contract DE-AC05-84ER40150. |
In recirculating accelerators, and in particular energy recovery linacs (ERLs), the maximum current has been limited by multipass, multibunch beam breakup (BBU), which occurs when the electron beam interacts with the higher-order modes (HOMs) of an accelerating cavity on the accelerating pass and again on the energy recovered pass. This effect is of particular concern in the design of modern high average current energy recovery accelerators utilizing superconducting technology. Experimental observations of the instability at the Jefferson Laboratory 10 kW Free-Electron Laser (FEL) are presented. Measurements of the threshold current for the instability are presented and compared to the predictions of several BBU simulation codes. To further characterize the instability, beam based measurements were made to determine the orientation of the dangerous HOMs. With BBU posing a threat to high current beam operation in the FEL, several suppression schemes were developed. These include direct damping of the dangerous HOMs and appropriately modifying the electron beam optics. Preliminary results of their effectiveness in raising the threshold current for stability are presented. |
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| TPAP003 | Exploring a Nonlinear Collimation System for the LHC | sextupole, collimation, betatron, insertion | 877 | ||
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We explore the adaptation of a nonlinear collimation system, as previously considered for linear colliders, to LHC betatron cleaning. A possible nonlinear system for LHC consists of a horizontal and vertical primary collimator located in between a pair of skew sextupoles. We discuss the modified LHC optics, the need for and optimum placement of secondary absorbers, and the simulated cleaning efficiency.
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| TPAP009 | Collimation in the Transfer Lines to the LHC | injection, septum, simulation, collimation | 1135 | ||
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Injection intensities for the LHC are over an order of magnitude above damage level. The TI 2 and TI 8 transfer lines between the SPS and LHC are each about 2.5 km long and comprise many active elements running in pulsed mode. The collimation system in the transfer lines is designed to dilute the beam energy sufficiently in case of accidental beam loss or mis-steered beam. A system using three collimator families spaced by 60 degrees in phase advance, both in the horizontal and the vertical plane has been chosen. We discuss the reasons for this choice, the layout and, the expected performance of the system in terms of maximum amplitudes and energy deposition.
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| TPAP015 | Commissioning of the LHC Beam Transfer Line TI 8 | instrumentation, proton, extraction, injection | 1461 | ||
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The first of the two LHC transfer lines was commissioned in autumn 2004. Beam reached an absorber block located some 2.5 km downstream of the SPS extraction point at the first shot, without the need of any threading. The hardware preparation and commissioning phase will be summarised, followed by a description of the beam tests and their results regarding optics and other line parameters, including the experience gained with beam instrumentation, the control system and the machine protection equipment.
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| TPAP018 | Optics Studies of the LHC Beam Transfer Line TI8 | quadrupole, coupling, extraction, emittance | 1578 | ||
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The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectories, dispersion and profile measurements. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. Residual coupling between the planes was evaluated using high statistics samples of trajectories. Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors. The paper presents the various analysis methods and their errors. The expected emittance growth arising from optical mismatch into the LHC is evaluated.
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| TPAP019 | Aperture Studies of the SPS to LHC Transfer Lines | simulation, dipole, injection, alignment | 1664 | ||
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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.
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| TPAP024 | Decoupling Schemes for the Tevatron in the Presence of Skew Quadrupole Fields | lattice, quadrupole, dipole, sextupole | 1850 | ||
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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. |
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| TPAP053 | IR Optics Measurement with Linear Coupling's Action-Angle Parameterization | coupling, dipole, background, heavy-ion | 3218 | ||
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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. |
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| TPAT006 | Impact of Optics on CSR-Related Emittance Growth in Bunch Compressor Chicanes | emittance, shielding, space-charge, synchrotron | 1015 | ||
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The dependence of emittance growth due to Coherent Synchrotron Radiation (CSR) in bunch compressor chicanes on optics has been noticed and empirically studied in the past. We revisit the subject, suggesting a model to explain slice emittance growth dependence on chicane optics. A simplified model to calculate projected emittance growth when it is mainly caused by transverse slice centroid offsets is presented. It is then used to find optimal compensation of centroid kicks in the single chicanes of a two-stage compression system by adjusting the phase advance of the transport in between and the ration of the compression factors.
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| TPAT030 | Transverse Beam Matching Application for SNS | emittance, SNS, linac, quadrupole | 2143 | ||
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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. |
An automated transverse beam matching application has been developed for the Spallation Neutron Source (SNS) beam transport lines. The application is written within the XAL Java framework and the matching algorithm is based on the simplex optimization method. Other functionalities, such as emittance calculated from profile monitor measurements (adopted from a LANL Fortran code), profile monitor display, and XAL on-line model calculation, are also provided by the application. Test results obtained during the SNS warm linac commissioning will be reported. A comparison between the emittances obtained from this application and an independent Trace-3D routine will also be shown. |
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| TPAT054 | Dispersion Matching of a Space Charge Dominated Beam at Injection into the CERN PS Booster | space-charge, injection, simulation, booster | 3283 | ||
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In order to match the dispersion at injection into the CERN PS Booster, the optics of the injection line was simulated using two different codes (MAD and TRACE). The simulations were benchmarked versus experimental results. The model of the line was then used to re-match the dispersion. Experimental results are presented for different optics of the line. Measurements with varying beam current show the independence of the measured quantity of space-charge effects.
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| TPAT076 | Measurement of the Luminous-Region Profile at the PEP-II IP, and Application to e± Bunch-Length Determination | luminosity, monitoring, simulation, collider | 3973 | ||
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The three-dimensional luminosity distribution at the interaction point (IP) of the SLAC B-Factory is measured continuously, using e+e- –> e+e- and e+e –> mu+mu- events reconstructed online in the silicon tracker of the BaBar detector. The centroid of the transverse luminosity profile provides a very precise and reliable monitor of medium- and long-term orbit drifts at the IP. The longitudinal centroid is sensitive to variations in the relative RF phase of the colliding beams, both over time and differentially along the bunch train. The measured horizontal r.m.s. width of the distribution is consistent with a sizeable dynamic-beta effect; it is also useful as a benchmark of strong-strong beam-beam simulations. The longitudinal luminosity distribution depends on the e± bunch lengths and vertical IP beta-functions, which can be different in the high- and low-energy rings. Using independent estimates of the beta-functions, we analyze the longitudinal shape of the luminosity distribution in the presence of controlled variations in accelerating RF voltage and/or beam current, to extract separate measurements of the e+ and e- bunch lengths.
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| TPAT083 | Computational Study of the Beam-Beam Effect in Tevatron Using the LIFETRAC Code | luminosity, emittance, simulation, antiproton | 4117 | ||
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Funding: Work supported by the Universities Research Assos., Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy. |
Results of a comprehensive numerical study of the beam-beam effect in the Tevatron are presented including the dependence of the luminosity lifetime on the tunes, chromaticity and optics errors. These results help to understand the antiproton emittance blow-up routinely observed in the Tevatron after the beams are brought into collision. To predict a long term luminosity evolution, the diffusion rates are increased to represent long operation time (~day) by using a small number of simulated turns. To justify this approach, a special simulation study of interplay between nonlinear beam-beam resonances and diffusion has been conducted. A number of ways to mitigate the beam-beam effects are discussed, such as increasing bunch spacing, separation between the beams and beam-beam compensation with electron lenses. |
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| TPAT084 | LIFETRAC Code for the Weak-Strong Simulation of the Beam-Beam Effect in Tevatron | betatron, simulation, antiproton, quadrupole | 4138 | ||
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Funding: Work supported by the Universities Research Assos., Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy. |
A package of programs for weak-strong simulation of beam-beam effects in hadron colliders is described. Accelerator optics parameters relevant to the simulation are derived from beam measurements and calculations are made using OptiM optics code. The key part of the package is the upgraded version of the LIFETRAC code which now includes 2D coupled optics, chromatic modulation of beta-functions, non-Gaussian shape of the strong bunches and non-linear elements for beam-beam compensation. Parallel computations are used and in the case of the Tevatron (2 main IPs + 70 parasitic IPs) the code has a productivity of ~1·1010 particles*turns/day on a 32-node cluster of Pentium IV 1.8 GHz processors. |
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| TOAB006 | SPEAR 3 - The First Year of Operation | feedback, injection, power-supply, dynamic-aperture | 505 | ||
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Funding: Work supported in part by Department of Energy Contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences. |
The first electrons were accumulated in the new 3-GeV SPEAR 3 storage ring in December, 2003, five days after the beginning of commissioning. By mid-January of 2004, the phas·10-1 current of 100 mA were stored. Ring characterization and tuning continued until early March when the first photon beam line was opened for users. By the end of the first run in July, SPEAR 3 beam properties and ring performance had been extensively measured by the accelerator and beam line groups. These included micron stability using slow orbit feedback, an emittance coupling of ~0.1% and 30-h lifetimes at 100 mA. During the present 2005 user run, turn-by-turn BPMs, fast orbit feedback, a high resolution UV synchrotron light monitor, and beam scrapers are being commissioned and 500-mA operation will be established. A modified lattice that will incorporate a double vertical waist chicane has been designed that will enable future installation of two small gap insertion devices. A study of top-off injection modes will also commence this year. The performance of SPEAR 3 during its first year of commissioning and operation, together with plans to improve performance, are described. |
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| TOAB009 | Generation of Short X-Ray Pulses Using Crab Cavities at the Advanced Photon Source | radiation, emittance, sextupole, simulation | 668 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
There is growing interest within the user community to utilize the pulsed nature of synchrotron radiation from storage ring sources. Conventional third-generation light sources can provide pulses on the order of 100 ps but typically cannot provide pulses of about 1 ps that some users now require to advance their research programs. However, it was recently proposed by A. Zholents et al. to use rf orbit deflection to generate subpicosecond X-ray pulses.* In this scheme, two crab cavities are used to deliver a longitudinally dependent vertical kick to the beam, thus exciting longitudinally correlated vertical motion of the electrons. This makes it possible to spatially separate the radiation coming from different longitudinal parts of the beam. An optical slit can then be used to slice out a short part of the radiation pulse, or an asymetrically cut crystal can be used to compress the radiation in time. In this paper, we present a feasibility study of this method applied to the Advanced Photon Source. We find that the pulse length can be decreased down to a few-picosecond range using superconducting crab cavities. *A. Zholents et al., NIM A 425, 385 (1999). |
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| TPPP002 | Global-Beta Measurement and Correction at the KEKB Rings | quadrupole, betatron, sextupole, closed-orbit | 802 | ||
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The global-beta correction is a part of the optics corrections which are performed to regularize the ring optics for the luminosity tunings. The global-beta measurement is performed by the reconstruction of the beta function from the set of the single kick orbits generated by the 6 kinds of the steering magnets. The distortion of the beta fucntion and the phase advance are corrected by the global beta correction using the fudge factors of power supplies of quadrupole magnets. These correction scheme are successfully working. In the typical case, the r.m.s. of the beta function beat and the betatron tune difference are corrected within 5% and 0.0005, respectively. In the luminosity run, we can operate the low energy ring(LER) with the horizontal betatron tune very close to half-integer(45.5050). In this paper, we will report in detail the global-beta measurement and correction techniques and its performance in the KEKB operation.
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| TPPP003 | Lattice Upgrade Plan for Crab Crossing at the KEKB Rings | lattice, quadrupole, luminosity, coupling | 865 | ||
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We plan to install two superconducting crab cavities into the rings at Janyary, 2006. In our plan, we will install one crab cavity per one ring into the NIKKO straight section where the cryogenic infrastructure is already operated for the superconducting accelerating cavities. In order to obtain the correct crabbing angle at the interaction point(IP), we have to enlarge the horizontal beta function(200m for HER) and have to adjust the horizontal phase advance between the IP and the cavity installation point. In this paper, we will report the lattice modified for the crab crossing and the study results about the single beam dynamics.
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| TPPP011 | Investigations of Injection Orbits at CESR Based on Turn-By-Turn BPM Measurements | injection, electron, positron, betatron | 1228 | ||
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Funding: National Science Foundation. |
Development of a data acquisition permitting turn-by-turn orbit measurements has been employed at CESR to study the optics of the injected electron beam. An optimization algorithm uses these measurements to determine the effective lattice functions describing the behavior of the injected electrons. We present comparisons of these measurements to tracking calculations of injection acceptance envelopes which account for the parasitic beam-beam interactions with the stored positron beam. |
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| TPPP016 | Beam Physics for the 12 GeV CEBAF Upgrade Project | linac, polarization, recirculation, damping | 1482 | ||
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Funding: Work supported by DOE Contract DE-AC05-84ER40150. |
Beam physics aspects of the 12 GeV Upgrade of CEBAF are presented. The CEBAF Upgrade to 12 GeV is achieved via 5.5 recirculations through the linacs, and the installation of 10 new high-gradient cryomodules. A new experimental hall, Hall D, is envisioned at the end of North Linac. Simulation results for straight-through and recirculated injectors are summarized and compared. Beam transport designs are discussed and evaluated with respect to matching and beam breakup (BBU) optimization. Effects of synchrotron radiation excitation on the beam properties are calculated. BBU simulations and derived specifications for the damping of higher order modes of the new 7-cell cavities are presented. The energies that provide longitudinal polarization in multiple experimental halls simultaneously are calculated. Finally, a detailed optics design for the Hall D transport line has been obtained. |
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| TPPP024 | Experimental Study of Crossing-Angle and Parasitic-Crossing Effects at the PEP-II e+e- Collider | luminosity, simulation, electron, quadrupole | 1874 | ||
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In a series of dedicated accelerator experiments, we have measured the dependence of the PEP-II luminosity performance on small horizontal crossing angles and on the horizontal separation at the first parasitic crossing. The experiment was carried out by varying the IP angle of one of the beams in two different bunch patterns, one with and one without parasitic crossings. The experimental measurements show satisfactory agreement with three-dimensional beam-beam simulations.
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| TPPP025 | Modeling Lost-Particle Accelerator Backgrounds in PEP-II Using LPTURTLE | scattering, background, vacuum, electron | 1889 | ||
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Funding: Department of Energy Contract DE-AC02-76SF00515. |
Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE a modified version of Decay TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar. |
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| TPPP032 | Proposal for a Multi-Use Test Beam Area in the SLAC B-Line | linac, quadrupole, target, emittance | 2221 | ||
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Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515. |
With the impending construction of the Linac Coherent Light Source (LCLS) at SLAC, displacing the well-used Final Focus Test Beam (FFTB) area, there is growing interest in developing a new test beam facility, available during LCLS operations and located in the old B-Line tunnel at the end of the linac. The success of the Sub-Picosecond Pulse Source (SPPS) and the desire to preserve this capacity suggests a new beamline with similar or improved electron beam quality, including bunch length compression to 10 microns. Beam availability during LCLS operations requires a new 1.2-km bypass line connecting the 2/3-point of the linac with the B-Line. A second operating mode, with LCLS not in use, involves a trajectory directly from the end of the linac to the B-line. This feature provides the highest beam quality at 30 GeV, and also allows a possible third operational mode by deflecting a few of the very high-brightness 120-Hz, 14-GeV LCLS bunches at low rate (1-10 Hz) into the B-line. Finally, linear collider research can be carried out in a short final focus system at the end of the B-Line, capable of producing a 70-nm rms beam size. We describe a possible design for these systems. |
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| WOAA004 | The ILC Beam Delivery System–Conceptual Design and R&D Plans | extraction, diagnostics, instrumentation, photon | 390 | ||
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The Beam Delivery System of the ILC has many stringent and sometimes conflicting requirements. To produce luminosity, the beams must be focused to nanometer size. To provide acceptable detector backgrounds, particles far from the beam core must be collimated. Unique beam diagnostics and instrumentation are required to monitor parameters of the colliding beams such as the energy spectrum and polarization. The detector and beamline components must be protected against errant beams. After collision, the beams must also be transported to the beam dumps safely and with acceptable losses. An international team is actively working on the design of the ILC Beam Delivery System in close collaboration. Details of the design, recent progress and remaining challenges will be summarized in this talk.
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| WPAE014 | Conceptual Design of a Longitudinal Halo Collimator for J-PARC Linac | linac, collimation, emittance, simulation | 1413 | ||
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In a high-intensity proton accelerator, avoidance of excess beam loss is essentially important to enable hands-on maintenance. To reduce the uncontrolled beam loss in the following ring, we plan to install a longitudinal halo collimator system in a beam transport line after the injector linac. The collimator system is supposed to have two main roles: One is the elimination of longitudinal tail or halo particles destined to be lost in the following ring, and the other is the removal of anomalous beams which can be resulted from, for example, RF discharge of an accelerating cavity. We plan to adopt a "periodic collimation scheme" in the collimator system taking advantage of the three-fold symmetry of the arc section. The momentum aperture of the collimator system is expected to be reduced by the factor of two adopting periodic collimation. In this paper, conceptual design of the collimator system is presented together with the results of particle simulations.
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| WOAC009 | Techniques for Measurement and Correction of the SNS Accumulator Ring Optics | betatron, quadrupole, SNS, injection | 674 | ||
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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) Accumulator Ring will reach peak intensities of 1.5x1014 protons/pulse through multi-turn charge-exchange injection. Accumulation of these unprecedented beam intensities must be accomplished while maintaining extremely low losses (less than 1 W/m). It is anticipated that the control of the ring optics will be important for achieving these low loss rates. We describe our plans for measuring and correcting the optical functions of the accumulator ring lattice. |
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| WOAC010 | Measurement of Linear Lattice Functions in the ESRF Storage Ring Using Turn-by-Turn Data | storage-ring, kicker, synchrotron, damping | 698 | ||
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A model-independent method to measure linear optics functions has been tested in turn-by-turn data from the ESRF storage ring. This method does not necessitate neither the knowledge of the model nor magnetic element manipulation. It uses only the positions measured in consecutive BPMs of betatron oscillations issued by small transverse kicks. The phase advances and tunes necessary to construct the transfer matrices are issued by refined Fourier analysis. The method's precision is compared with classical methods such as response matrix analysis and beam matrix construction.
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| ROAA004 | MICE: The International Muon Ionisation Cooling Experiment | emittance, instrumentation, synchrotron, coupling | 398 | ||
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Muon storage rings have been proposed for use as sources of intense high-energy neutrino beams and as the basis for multi-TeV lepton-antilepton colliding beam facilities. To optimise the performance of such facilities is likely to require the phase-space compression (cooling) of the muon beam prior to acceleration and storage. The short muon-lifetime makes it impossible to employ traditional techniques to cool the beam while maintaining the muon-beam intensity. Ionisation cooling, a process in which the muon beam is passed through a series of liquid hydrogen absorbers followed by accelerating RF-cavities, is the technique proposed to cool the muon beam. The international Muon Ionisation Cooling Experiment (MICE) collaboration has been formed to carry out a muon-cooling demonstration experiment, and its proposal to Rutherford Appleton Laboratory has been approved. The MICE cooling channel, the instrumentation and the implementation at the Rutherford Appleton Laboratory is described together with the predicted performance of the channel and the measurements that will be made.
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| RPAE003 | Optimization and Modeling Studies for Obtaining High Injection Efficiency at the Advanced Photon Source | injection, septum, booster, quadrupole | 871 | ||
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Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
In recent years, the optics of the Advanced Photon Source storage ring has changed to lower equilibrium emittance (2.5 nm-rad) but at the cost of stronger sextupoles and stronger nonlinearities, which have reduced the injection efficiency from 100% in the high emittance mode. Over the years we have developed a series of optimization, measurement and modeling studies of the injection process, which allows us to obtain or maintain low injection losses. For example, the trajectory in the storage ring is optimized with trajectory knobs for maximum injection efficiency. This can be followed by collecting first-turn trajectory data, from which we can fit the initial phase-space coordinates. The model of the "optimized" trajectory would show whether the beam comes too close to a physical aperture in the injection magnets. Another modeling step is the fit and correction of the transfer line optics, which has a significant impact on phase-space matching. |
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| RPAE022 | Improved Long Radius of Curvature Measurement System for FEL Mirrors | laser, wiggler, electron, radiation | 1787 | ||
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Funding: This work is supported by the U.S. AFOSR MFEL grant F49620-001-0370. |
The 53.73 meter long Duke free electron laser (FEL) cavity consists of two concave mirrors with radius of curvature longer than 27 meters. A proper radius of curvature is designed to achieve an optimal and stable operation of the FEL. This requires accurate measurements of the cavity mirror's radius of curvature before its initial installation. Subsequent radius of curvature measurements are performed to ensure no significant deformation of the mirror occurs after a period of extensive use. A direct measurement based upon the geometric optics principles has been used at DFELL for years. Recently, we have significantly upgraded this measurement apparatus by utilizing a HeNe laser as the light source and a straight wire with a proper size as the object. In this paper we describe the details of the measurement setup and report the benefits of the recent upgrades. In addition, we report the improved data analysis technique and results of recent long radius of curvature measurements. |
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| RPAE027 | Linear Optics Measurements in the ESRF Booster | booster, sextupole, injection, dipole | 1973 | ||
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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.
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| RPAE028 | Lattice Upgrade Options for the ESRF Storage Ring | emittance, dipole, lattice, quadrupole | 2047 | ||
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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.
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| RPAE029 | Analytical Considerations for Reducing the Effective Emittance with Variable Dipole Field Strengths | emittance, dipole, betatron, damping | 2086 | ||
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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.
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| RPAE037 | Operation with a Low Emittance Optics at ANKA | emittance, injection, storage-ring, resonance | 2467 | ||
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ANKA is a synchrotron light source operating in an energy range from 0.5 to 2.5 GeV. The electron storage ring at ANKA is designed as a variation of an eightfold Double Bend Achromat structure. Since its commissioning the facility has been operated with zero dispersion in the long straight sections resulting in an emittance of about 100 nmrad. Since mid 2004 ANKA is operated with dispersion distributed over the complete ring thus reducing the emittance to 40 nmrad. In the course of the re-design of the storage ring optics a compensation of higher order field components leads to a visibly increased momentum acceptance. Optics calculations and measurements as well as operational experience will be discussed.
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| RPAE038 | Far Infrared Coherent Synchrotron Edge Radiation at ANKA | radiation, synchrotron, storage-ring, synchrotron-radiation | 2518 | ||
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A synchrotron radiation source emits coherent infrared (IR) radiation when the electron bunch length is comparable to the wavelength of the emitted radiation. To generate coherent radiation in the far IR (THz) region, a "low alpha mode" has been devised at the ANKA storage ring operating at 1.3 GeV. The corresponding lattice has a significantly reduced momentum compaction factor. The spectral dependence of the emitted radiation is recorded at the ANKA-IR beamline, where the synchrotron light is produced in the fringe field of a bending magnet. This edge radiation has the advantage of being more collimated than constant field radiation. This allows the observation of frequencies down to 1 cm-1 through a modest vertical aperture, which would not be possible with classical constant field emission due to the increasing beam divergence with decreasing frequency. The onset of coherent emission is found at a synchrotron frequency of about 10 kHz. At 5 kHz, an intensity enhancement of up to 5 orders of magnitude, with respect to the incoherent emission, is observed in the spectral range between 1 and 65 cm-1.
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| RPAE068 | Very Short Bunches in MIT-Bates South Hall Ring | lattice, electron, synchrotron, radiation | 3768 | ||
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Funding: Department of Energy |
The study of ultra-short bunches in MIT SHR storage ring with very small momentum compactions is carried out. The ultra-short bunches are to greatly enhence the coherent radiation by many orders of magnitude. The ring lattice is resigned to reach very small momentum compaction factor down to 1·10-5 levels. The measurement is performed with the streak camera. The various associated issues are discussed. |
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| RPAP049 | Beam Diagnostics with Optical Fiber Optics | feedback, synchrotron, synchrotron-radiation, radiation | 3040 | ||
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Optical fiber has been widely used for communications. It is a waveguide with very high-frequency bandwidth. Therefore, it has broad applications for high-frequency related signals such as high-energy Accelerator beam signls. Research and developments has been done to measure charged particle beam and synchrotron radiation with optical fiber based instruments developed by the author. The paper will describe and discuss the experiments and testing of charged particle beams and synchrotron radiation that haverecently been performed.
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| RPAT051 | Measurement of Dynamic Beam-Beam Effects on Horizontal Beam Size at KEKB Using SR Interferometer Equipped with Retrofocus Optics | emittance, simulation, beam-beam-effects, positron | 3150 | ||
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Transverse beam-size enlargement due to dynamic beta and beam-beam effects has been observed in the KEKB Low Energy Ring (LER) and High Energy Ring (HER). In order to observe these effects, a retrofocus optics system has been developed and installed in the horizontal SR interferometers at the HER and LER. This system allows us to vary the apparent beam size to match the dynamic range of the interferometer. We report on the retrofocus optics system and measurement results, and compare the measured effects with those expected from dynamic beta simulations.
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| RPAT067 | Beam Angle Measurement Using Cherenkov Radiation | electron, radiation, scattering, photon | 3742 | ||
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A simple beam angle monitor utilizing observation of far-field Cherenkov radiation is being developed. The monitor is independent of beam energy as well as position and requires only modest camera sensitivity. Since the wavefront of Cherenkov radiation is not spherical but planar, the far-field image is supposed to be infinetesimally small in one-dimensional geometrical optics, which may result in high angular resolution. In a practical experiment, however, beam scattering in a radiator and diffraction from a finite size radiation source determine the resolution. Numerical analysis shows that the angular resolution with a 100-um thickness fused silica radiator is 0.8 mrad. The experimental results with 2-mm and 100-um thickness fused silica are shown. The possibility of non-destructive measurement is also discussed.
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| RPAT069 | Electron Beam Size Measurements in a Cooling Solenoid | electron, antiproton, radiation, focusing | 3801 | ||
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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 a straight trajectory and constant beam size to provide effective cooling of the antiprotons in the Recycler. A measurement system was developed using movable appertures and steering bumps to measure the beam size in a 20 m long, nearly continuous, solenoid. This paper discusses the required beam parameters, the implimentation of the measurement system and results for our application. |
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| RPAT077 | Beam Test Proposal of an ODR Beam Size Monitor at the SLAC FFTB | target, radiation, photon, monitoring | 4015 | ||
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We design a single bunch transverse beam size monitor which will be tested to measure the 29 GeV electron/positron beam at the SLAC FFTB beam line.The beam size monitor uses a CCD camera to make images of the interference pattern of the optical diffraction radiation from conductive slit target which are placed close to the beam path. In this method, destruction of the accelerated electron/positron beam bunches due to the beam size monitoring is negligible, which is vital to the operation of the Linear Collider project. A dis-phased conductive slit target and a lens system allow us to recover the sensitivity of the transverse beam size with a small photon yield ratio at the valley to that at the peak due to the large gamma*λ, and with the near field effect due to the large λ*gamma**2. A solution for non-negligible divergence at the SLAC FFTB is also discussed.
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| RPAT080 | The SPEAR 3 Diagnostic Beamlines | coupling, radiation, synchrotron, emittance | 4057 | ||
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Funding: Work supported in part by DOE contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences. |
SPEAR 3 is equipped with an x-ray pinhole camera and a visible/UV beam line to evaluate electron beam properties. The pinhole camera has a 30 x 25 micron Ta aperture and 60% image demagnification on a phosphor screen. The image is captured by a National Instruments frame-grabber on a remote computer with a parallel video signal for control room monitoring. The visible/UV beam line features a horizontal ± 0.3 mrad ‘cold finger’ to remove the x-ray core of the beam. The remaining visible/UV light is deflected 18 degrees onto an optical bench where it is focused via refractive Cassegrain optics. The beam is then split into parallel optics for gated- and streak camera measurements. This paper describes the experimental set up and preliminary measurements obtained with both systems. |
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| RPAT087 | Design of a High-Resolution Optical Transition Radiation Imager System for the Linac Coherent Light Source Undulator | electron, undulator, radiation, linac | 4209 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38. |
The Linac Coherent Light Source (LCLS), a free-electron x-ray laser, is under design and construction. Its high intensity electron beam, 3400 A in peak current and 46 TW in peak power, is concentrated in a small area (30 micrometer rms in both horizontal and vertical directions) inside its undulator. Ten optical transition radiation (OTR) imagers are planned between the undulator segments for the characterization of the transverse profiles of the electron beam. In this paper, we present the performance requirements and technical requirements of the OTR imagers. We will discuss in detail the design of the OTR screen, the arrangement and modeling of the imaging optics, and the mechanical design and analysis of the compact camera module. Through a unique optical arrangement, this imager will achieve a fine resolution (12 micrometer rms or better) over the entire field of view (5 mm × 5 mm). The compact camera module will fit in the limited space available with remote focus adjustment. A digital camera will be used to read out the beam images in a programmable region (5 mm × 0.5 mm) at the full beam repetition rate (120 Hz), or over the entire field at a lower rate (15 Hz). |
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| RPAT089 | Advances in Optical Transition and Diffraction Radiation Emittance Diagnostics | emittance, electron, simulation, diagnostics | 4224 | ||
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Funding: Office of Naval Research and the DOD Joint Technology Office. |
We have performed a series of experiments using Optical Transition Radiation and Optical Diffraction Radiation Interferometry to measure the two orthogonal (x,y) rms divergences of the Brookhaven National Laboratory’s Advanced Test Facility electron beam operating at an energy of 50 MeV. Measurement of the rms divergences at the (x,y) beam waist conditions, together with corresponding measurements of the rms beam sizes allows a determination of the rms x and y emittances. A comparison of the results using OTRI and ODTRI are presented. |
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| RPPE029 | Rotating Aperture Deuterium Gas Cell Development for High Brightness Neutron Production | linac, vacuum, beam-transport, target | 2074 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. |
A project is underway at LLNL to design and build a system for fast neutron imaging. The approach being pursued will use a 7 MeV deuterium linac for producing high-energy neutrons via a D(d,n)3He reaction. To achieve a high-brightness neutron source, a windowless rotating aperture gas cell approach is being employed. Using a series of close-tolerance rotor and stator plates, a differential pumping assembly has been designed and built that contains up to 3 atmospheres of deuterium gas in a 40 mm long gas cell. Rarefaction of the gas due to beam-induced heating will be addressed by rapidly moving the gas across the beam channel in a crossflow tube. The design and fabrication process has been guided by extensive 3D modeling of the hydrodynamic gas flow and structural dynamics of the assembly. Summaries of the modeling results, the fabrication and assembly process for the rotating aperture system, and initial measurements of gas leakage shall be presented. |
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| RPPP003 | Proposal of the Next Incarnation of Accelerator Test Facility at KEK for the International Linear Collider | damping, linear-collider, collider, extraction | 874 | ||
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The realization of the International Linear Collider (ILC) will require the ability to create and reliably maintain nanometer size beams. The ATF damping ring is the unique facility where ILC emittancies are possible. In this paper we present and evaluate the proposal to create a final focus facility at the ATF which, using compact final focus optics and an ILC-like bunch train, would be capable of achieving 35nm beam size. Such a facility would enable the development of beam diagnostics and tuning methods, as well as the training of young accelerator physicists.
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| RPPP028 | Simulation of Wake Field Effects on High Energy Particle Beams | collimation, linear-collider, simulation, collider | 2018 | ||
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We discuss the wake fields that are liable to arise in the Beam Delivery System of a Future Linear Collider, and we present studies made using the MERLIN simulation program of the effects such fields would have on the bunch shape and hence the luminosity of the proposed design.
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| RPPP030 | Design of ILC Extraction Line for 20 mrad Crossing Angle | extraction, luminosity, diagnostics, beam-losses | 2134 | ||
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Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. |
One of the two ILC Interaction Regions will have a large horizontal crossing angle which would allow to extract the spent beams in a separate beam line. In this paper, the extraction line design for 20 mrad crossing angle is presented. This beam line transports the primary e+/e- and beamstrahlung photon beams from the IP to a common dump, and includes diagnostic section for energy and polarization measurements. The optics is designed for a large energy acceptance to minimize losses in the low energy tail of the disrupted beam. The extraction optics, diagnostic instrumentation and particle tracking simulations are described. |
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| RPPP047 | Global Optimization of Damping Ring Designs Using a Multi-Objective Evolutionary Algorithm | wiggler, damping, sextupole, lattice | 2962 | ||
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Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
Several damping ring designs for the International Linear Collider have been proposed recently. Some of the specifications, such as circumference and bunch train, are not fixed yet. Designers must make a choice anyway, select a geometry type (dog-bone or circular), an arc cell type (TME or FODO), and optimize linear and nonlinear part of the optics. The design process include straightforward steps (usually the linear optics), and some steps not so straightforward (when nonlinear optics optimization is affected by the linear optics). A first attempt at automating this process for the linear optics is reported. We first recognize that the optics is defined by just a few primary parameters (e.g., phase advance per cell) that determine the rest (e.g., quadrupole strength). In addition to the exact specification of circumference, equilibrium emittance and damping time there are some other quantities which could be optimized that may conflict with each other. A multiobjective genetic optimizer solves this problem by producing a population of best-ranked solutions on a multi-dimensional surface from which one solution can be chosen by the designer. The application of the NSGA-II optimizer to a damping ring of FODO cells is presented. |
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| RPPT011 | Optimized Bunch Compression System for the European XFEL | emittance, space-charge, linac, RF-structure | 1236 | ||
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The European XFEL bunch compressor system has been optimized for greater flexibility in parameter space. Operation beyond the XFEL design parameters is discussed in two directions: achieving the uppermost number of photons in a single pulse on one hand and reaching the necessary peak current for lasing with a pulse as short as possible on the other. Results of start-to-end calculations including 3D-CSR effects, space charge forces and the impact on wake fields demonstrate the potential of the XFEL for further improvement or, respectively, its safety margin for operation at design values.
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| RPPT026 | Status of a Plan for an ERL Extension to CESR | linac, emittance, undulator, electron | 1928 | ||
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Funding: Cornell University. |
We describe the status of plans to build an Energy-Recovery Linac (ERL) X-ray facility at Cornell University. This 5 GeV ERL is an upgrade of the CESR ring that currently powers the Cornell High Energy Synchrotron Source (CHESS). Due to its very small electron-beam emittances, it would dramatically improve the capabilities of the light source and result in X-ray beams orders of magnitude better than any existing storage ring light source. The emittances are based upon simulations for currents that are competitive with ring-based sources. The ERL design that is presented has to allow for non-destructive transport of these small emittances. The design includes a series of X-ray beamlines for specific areas of research. As an upgrade of the existing storage ring, special attention is given to reuse of many of the existing ring components. Options of bunch compression are discussed, tolerances for emittance growth are specified, and simulations of the beam-breakup instability and methods of increasing its threshold current are shown. This planned upgrade illustrates how other existing storage rings could be upgraded as ERL light sources with vastly improved beam qualities. |
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| RPPT049 | Linear Optics Compensation of the Superconducting Wiggler in HLS | wiggler, quadrupole, storage-ring, focusing | 3037 | ||
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Hefei Light Source is a dedicated VUV light source. A superconducting wiggler magnet with 6 Tesla magnetic field was installed on the storage ring to generate hard X-ray radiation. With the compensation of tune shift due to insertion device, beam was successfully stored, but the beam lifetime was decreased much. In order to cure the lifetime, a simple hard-edge model of the wiggler was constructed in lattice simulation code and the compensation scheme was extensively studied again. Calculation showed that it is difficulty to localize the strong focusing effects from wiggler magnet. Then, a new scheme was brought forward and experimental result showed that it can restore the beam lifetime largely. As the application of LOCO method in HLS, a new compensation scheme was calculated by response matrix fitting, and the experimental result also presented in this paper.
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| FPAE004 | Optical Matching of Slowly Extracted Beam with Transport System at HIMAC | simulation, extraction, emittance, heavy-ion | 910 | ||
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The optical matching between the ring and the transport line plays important role in order to control the beam size and profile after the transport. At HIMAC, thus, we have studied the optical matching of the slowly extracted beam. As a result, it was verified that the beam size of the slowly extracted beam were controlled owing to the optical matching. It was also found that small deviation of quadrupole strength in the ring brings orbit distortion at the transport system.
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| FPAT003 | Joining the RHIC Online and Offline Models | simulation, lattice, insertion, luminosity | 880 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy. |
The paper presents an interface encompassing the RHIC online ramp model and the UAL offline simulation framework. The resulting consolidated facility aims to minimize the gap between design and operational data, and to facilitate analysis of RHIC performance and future upgrades in an operational context. The interface is based on the Accelerator Description Exchange Format (ADXF), and represents a snapshot of the RHIC online model which is in turn driven by machine setpoints. This approach is also considered as an intermediate step towards integrating the AGS and RHIC modeling environments to produce a unified online and offline AGS model for operations. |
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| FPAT006 | CHEF: An Interactive Program for Accelerator Optics Calculations | lattice, factory, target, controls | 988 | ||
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Funding: Fermilab is operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy. |
We introduce CHEF, a program built on a "Collaborative Hierarchical Exploratory Framework" for doing optical calculations in accelerator physics. CHEF organizes and shares information between independent components that employ graphical user interfaces for interactive use. Among them are: a browser to display the beamline model's structure; a site viewer to show a line's geometry; phase space windows to oversee development of tracking calculations; a trace window to display the passage of a probe particle through beam position monitors; a plotter for displaying optical functions; a parser which constructs beamline models defined in MAD8 format and allows for interactive editing and debugging of the lattice files. Calculations are carried out by a hierarchy of C++ class libraries, most notably: MXYZPTLK handles automatic differentiation and differential algebra; BEAMLINE contains classes for modeling accelerator components; PHYSICS_TOOLKIT encapsulates specific calculations. Python bindings to these libraries and to CHEF's components, in conjunction with an embedded interpreter, provide a mechanism to extend and customize CHEF's functionality. |
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| FPAT007 | The Fermilab Lattice Information Repository | lattice, antiproton, coupling, collider | 1066 | ||
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Funding: Fermilab is operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy. |
Fermilab is a large accelerator complex with six rings and sixteen transfer beamlines operating in various modes and configurations, subject to modifications, improvements and occasional major redesign. Over the years, it became increasingly obvious that a centralized lattice repository with the ability to track revisions would be of great value. To that end, we evaluated potentially suitable revision systems, either freely available or commercial, and decided that expecting infrequent users to become fully conversant with complex revision system software was neither realistic nor practical. In this paper, we discuss technical aspects of the recently introduced FNAL Accelerator Division's Lattice Repository, whose fully web-based interface hides the complexity of Subversion, a comprehensive open source revision system. In particular we emphasize how the architecture of Subversion was a key ingredient in the technical success of the repository's implementation. |
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| FPAT059 | Event Driven Automatic State Modification of BNL's Booster for NASA Space Radiation Laboratory Solor Particle Simulator | booster, ion, radiation, extraction | 3447 | ||
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Funding: Work performed under Contract #DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy. |
The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. NASA is interested in reproducing the energy spectrum from a solar flare in the space environment for a single ion species. To do this we have built and tested a set of software tools which allow the state of the Booster and the NSRL beam line to be changed automatically. In this report we will desribe the system and present results of beam tests. |
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| FPAT089 | A Parallel Simplex Optimizer and Its Application to High-Brightness Storage Ring Design | dynamic-aperture, storage-ring, emittance, target | 4230 | ||
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Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
Optimization is commonly used in accelerator design to find linear optics solutions. Such optimizations are usually fairly fast as linear optics computations are themselves fast. For high-brightness storage rings, optimization of nonlinear elements (e.g., sextupoles) is also important in obtaining sufficient dynamic aperture. However, this can be very time onsuming as the basic calculations are time consuming. We have developed an efficient parallel Simplex optimizer that runs on a Linux cluster. It can optimize the result of running essentially any program or script that returns a penalty function value. We have used this optimizer with elegant to optimize dynamic aperture of storage ring designs. We discuss the optimization algorithm and performance, design of penalty functions, and optimization results. |
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