| Paper | Title | Other Keywords | Page | ||
|---|---|---|---|---|---|
| MOPA001 | Advances in the Understanding and Operations of Superconducting Colliders | dipole, injection, coupling, multipole | 54 | ||
|
Chromaticity drift is a well-known and more or less understood phenomenon in superconducting colliders such as the Tevatron. Less known is the effect of tune and coupling drift, also observed in the Tevatron during injection. Recently, in the context of the Tevatron collider run II, extensive studies of chromaticity, tune and coupling drifts were conducted to improve Tevatron performance. The studies included not only beam studies but also extensive off-line magnetic measurements on spare Tevatron dipoles. Some of these measurements were conducted in collaboration with Cern. Cern’s interest in multipole drifts is related to the future LHC, which will have similar issues. The following will report on the results of these studies. A new result, which will be presented here also, is related to fast drifts occurring in the first few seconds of the injection porch. These fast drifts were observed first in the Tevatron and efforts are underway to explain them. The author will also attempt to broaden the discussion to include the discussion of drift effects in the accelerating fields of superconducting linear accelerators.
|
|
|
||
| MOPA010 | Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron | injection, dipole, coupling, collider | 725 | ||
|
Chromaticity drift is a well-known and more or less well-understood phenomenon in superconducting colliders such as the Tevatron. Less known is the effect of tune and coupling drift, also observed in the Tevatron during injection. These effects are caused by field drifts in the superconducting magnets. Understanding of the behavior of the tune, coupling, and chromaticity at the start of the ramp is an important part of understanding the observed 5-10% loss in beam intensity at the start of the Tevatron ramp. In addition modifications in the Tevatron shot set-up procedure are being implemented to allow for a gain in integrated luminosity. In this context we conducted several beam-studies, during the period of April to August 2004, in which we measured the drift in the Tevatron chromaticity, tune and coupling during the injection porch. In some case we also measured the snapback at the start of the ramp. We will present the results of these studies data and put them into context of the results of off-line magnetic measurements conducted in spare Tevatron dipoles at the same time. Finally we will propose optimized feed-forward algorithms that successfully compensate for the drift effects in the Tevatron.
|
|
|
||
| MPPE004 | Evaluation of Nonlinear Effects in the 3GeV Rapid Cycling Synchrotron of J-PARC | resonance, dipole, simulation, multipole | 916 | ||
|
In order to accelerate an ultra-high intense beam with small particle losses, the 3GeV Rapid Cycling Synchrotron (RCS) of J-PARC, which is being constructed at JAERI, has a large acceptance. In this case the nonlinearity associated with the motion of particles at large amplitude and large momentum deviation plays a significant role. The sources of nonlinear magnetic fields in RCS are mainly connected with the fringe of the main dipole and quadrupole magnets and with the sextupole magnets used for the linear chromaticity correction. In this paper, we will present simulation results including such nonlinear effects. In addition, the possible correction scheme for the induced transverse resonances will be discussed.
|
|
|
||
| MPPE005 | Dynamic Aperture and Resonance Correction for JPARC-RCS | resonance, injection, dynamic-aperture, quadrupole | 979 | ||
|
Main intrinsic field nonlinearities, which are common for synchrotrons with large aperture, are the nonlinear field of the bending magnets, the fringing field of the magnets and the sextupole field nonlinearity, used for the chromaticity correction. The particle motion in the ring bending magnets has been analyzed by two methods: (1) by direct integration of the particle motion equations in the 3D magnetic field (Tosca output), based on the 4th order Runge-Kutta integrator and (2) by determination the transfer 8th order map of the bending magnet by using the Gaussian wavelet in the 3D space. The second technique allows us to use powerful tools such as the normal form analysis, to define the resonance driving terms, which can be used for the resonance correction. As the result of this study it was shown that the main limitation of the RCS dynamic aperture can be caused by the structure normal sextupole-order resonance and the normal octupole-order resonance. Other high-order resonances have smaller effects on the particles motion than the resonances mentioned above. The correction scheme to improve the dynamic aperture near the normal sextupole-order resonance has been analyzed.
|
|
|
||
| MPPE015 | Non-Linear Ring Model Calibration with Frequency Analysis of Betatron Oscillations | lattice, resonance, target, betatron | 1452 | ||
|
A precise model of an accelerator ring is crucial to achieve ultimate performance both in synchrotron light sources and high energy synchrotrons. Algorithms have been developed to calibrate the linear model of the ring. They have been successfully applied experimentally to determine and correct the linear optics of the machine. More recently the Frequency Map Analysis has been used to model also the non-linear optics. We propose here a technique based on the fit of non-linear spectral lines to recover the non-linear driving terms and to compensate the non-linear field errors around the ring.
|
|
|
||
| MPPE020 | Control of Dynamic Aperture for Synchrotron Light Sources | optics, radiation, emittance, lattice | 1670 | ||
|
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. |
|
||
| MPPE022 | Modification to the Lattice of the Fermilab Debuncher Ring To Improve the Performance of the Stochastic Cooling Systems | lattice, quadrupole, antiproton, injection | 1799 | ||
|
Funding: Supported by the Department of Energy and the National Science Foundation. |
The Fermilab Debuncher is used to collect antiprotons from the production target, reduce the momentum spread of the beam by an RF bunch rotation, and stochastically cool the transverse and longitudinal emittances of the beam prior to transfer to the Accumulator. A large value of the slip factor of the ring lattice is favored to provide a larger momentum acceptance for the bunch rotation process, while a small value of the slip factor is desirable for stochastic cooling. A dynamic change in the lattice from a large slip factor at injection to a smaller slip factor at extraction would optimize both processes and could lead to an improvement in antiproton stacking rate. This paper discusses the details of lattice modifications to the Debuncher, achievable with the existing hardware, which would result in a 60% increase in the slip factor, while maintaining the tunes and chromaticities fixed, and keeping the betatron functions within an acceptable range. |
|
||
| MPPE028 | Non Linear Error Analysis from Orbit Measurements in SPS and RHIC | simulation, interaction-region, scattering, resonance | 2012 | ||
|
Funding: U.S. Department of Energy and Colciencias. |
Recently, an "action and phase" analysis of SPS orbits measurements proved to be sensitive to sextupole components intentionally activated at specific locations in the ring. In this paper we attempt to determine the strenght of such sextupoles from the measured orbits and compare them with the set values. Action and phase analysis of orbit trayectories generated by RHIC models with non linearities will also be presented and compare with RHIC experiments. |
|
||
| MPPE030 | Comparison of Off-Line IR Bump and Action-Angle Kick Minimization | octupole, simulation, resonance, interaction-region | 2116 | ||
|
Funding: Work supported by U.S. DOE under contract No. DE-AC02-98CH10886. |
The interaction region bump (IR bump) nonlinear correction method has been used for the sextupole and octupole field error on-line corrections in the Relativistic Heavy Ion Collider (RHIC). Some differences were found for the sextupole and octupole corrector strengths between the on-line IR bump correction and the predictions from the action-angle kick minimization. In this report we compare the corrector strengths from these two methods based on the RHIC Blue ring lattice with the IR nonlinear modeling. The comparison confirms the differences between resulting corrector strengths. And the reason for the differences is found and discussed. It is followed by a further discussion of the operational IR bump applications to the octupole, and skew sextupole and skew quadrupole field error corrections. |
|
||
| MPPE056 | Studies to Increase the Anti-Proton Transmission from the Target to the Debuncher Ring | lattice, antiproton, quadrupole, simulation | 3357 | ||
|
Funding: This work was supported by the Director, Office of Science, High Energy Physics, U.S. Department of Energy under Contracts No. DE-AC03-76SF00098 and DE-AC02-76CH03000. |
The AP2 beamline at Fermilab transports anti-protons from the production target to the Debuncher ring. The measured admittance of the Debuncher ring and the theoretical aperture of the line are larger than the size of the transmitted beam. Extensive tracking studies were done using the Accelerator Toolbox (AT) to understand the sources of the difference. As simulations pointed to chromatic effects being a source of problems, measurements were done to study this. Several possible remedies were studied including adding sextupoles to the line to reduce the chromatic effects. |
|
||
| MPPE061 | Measurement and Correction of Nonlinear Chromaticity in RHIC | octupole, insertion, optics, luminosity | 3523 | ||
|
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. |
|
||
| MPPE064 | Dynamic Aperture Study and Lifetime Improvement at the Advanced Photon Source | dynamic-aperture, coupling, resonance, injection | 3632 | ||
|
Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
Over past few years, the optics of the Advanced Photon Source storage ring was optimized to provide lower natural emittance. Presently, APS operates at 2.5 nm-rad emittance. The optimization was done at the expense of stronger sextupoles and shorter lifetime. Here we present our work on measurement and understanding the dynamic aperture of APS in low-emittance mode. We found good agreement between the dynamic aperture measurements and that of the model derived from the response matrix analysis. Based on the model, we were able to increase the lifetime significantly by optimizing sextupoles, correcting optics, moving working point, and adjusting rf voltage. The higher lifetime allowed us to decrease operating coupling from 2.5% to 1%. |
|
||
| MPPE074 | Commissioning of a Locally Isochronous Lattice at ALS | lattice, quadrupole, injection, coupling | 3922 | ||
|
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. |
With the advance of ultrafast science, manipulating electron beam at the sub-micron and nanometer scale has been actively pursued. A special lattice of the ALS storage ring was conceived to studythe sub-micron longitudinal structure of the beam. It contains sections that are isochronous to the firstorder. Due to the practical constraints of the accelerator, sextupoles have to be off and the dispersion at the injection point is 60 cm, which make commissioning a highly nontrivial task. After a few months of tuning, we have been able to store at 30 mA of beam at the life time of 2 hours. After a brief introduction to the motivation of the experiment and the design of the lattice, the process and more detailed results of the commissioning will be presented. Future plan will also be discussed. |
|
||
| MPPE083 | Harmonic Decomposition of Orbit Data for Multipole Analysis | coupling, multipole, extraction, dipole | 4120 | ||
|
The unprecedented position resolution provided by the newly commissioned Recycer BPM system is opening up a new chapter of beam based multipole analysis at Fermilab. The closed orbit data, taken with circulating beam and averaged over many consecutive turns, has been shown to have the resolution of a few microns. The result of polynomial fit to BPM position data, as a function of dipole kick sizes, is used to separate orbit data into first, second, and third order. Combining both the in-plane and cross-plane orbit data it is possible to determine the multipole content within each half cell. This paper presents the algorithm behind the procedure, the data collected from the Fermilab Recycler Ring, and the final analysis result.
|
|
|
||
| MPPT004 | End Chamfer Study and Field Measurements of the BEPCII Dipoles | dipole, multipole, quadrupole, factory | 919 | ||
|
The new BEPCII double ring will be added in the existing BEPC tunnel. There are more than 40 bending magnets named 67B in the new ring. The 67B is conventional ‘C’-type dipole magnet. The magnetic filed properties are dominated by the magnet end effect. The end effect have been studied and minimized by a proper end chamfer. Magnetic measurements of the prototype and productions were carried out using long coil. The developing process of the pole end chamfers and the measurement results of the 67B prototype and batch productions are described in the paper.
|
|
|
||
| MPPT010 | A New Correction Magnet Package for the Fermilab Booster Synchrotron | quadrupole, dipole, booster, multipole | 1204 | ||
|
Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-76CH03000. |
Since its initial operation over 30 years ago, most correction magnets in the Fermilab Booster Synchrotron have only been able to fully correct the orbit, tunes, coupling, and chromaticity at injection (400MeV). We have designed a new correction package, including horizontal and vertical dipoles, normal and skew quadrupoles, and normal and skew sextupoles, to provide control up to the extraction energy (8GeV). In addition to tracking the 15Hz cycle of the main, combined function magnets, the quadrupoles and sextupoles must swing through their full range in 1ms during transition crossing. The magnet is made from 12 water-cooled racetrack coils and an iron core with 12 poles, dramatically reducing the effective magnet air gap and increasing the corrector efficiency. Magnetic field analyses of different combinations of multipoles are included. |
|
||
| MPPT031 | Radiation Resistant Magnets for the RIA Fragment Separator | radiation, target, quadrupole, dipole | 2200 | ||
|
Funding: Supported in part by Michigan State University and the U.S. DOE. |
The high radiation fields around the production target and the beam dump in the fragment separator at the Rare Isotope Accelerator requires that radiation resistant magnets be used. Because large apertures and high gradients are required for the quadrupoles and similar demanding requirements for the dipole and sextupoles, resistive coils are difficult to justify. The radiation heating of any materials at liquid helium temperatures also requires that superconducting versions of the magnets have low cold-masses. The final optical design has taken the practical magnets limits into account and sizes and fields adjusted to what is believed to be achievable with technology that is possible with sufficient R&D. Designs with higher obtainable current densities and having good radiation tolerances that use superconducting coils are presented, as well as the radiation transport calculations that drive the material parameters. |
|
||
| MPPT040 | The LHC Magnetic Field Model | injection, dipole, coupling, superconducting-magnet | 2648 | ||
|
The compensation of the dynamic field changes during the proton and ion beam injection and acceleration in the LHC requires an accurate forecast and an active control of the magnetic field in the accelerator. The LHC Magnetic Field Model is the core of this magnetic prediction system. This open loop control scheme will provide the desired field components at a given time, magnet operating current, magnet ramp-rate, magnet temperature and magnet powering history to the required precision. The model is based on the identification and physical decomposition of the effects that contribute to the total field in the magnet aperture of the LHC dipoles. By using data obtained from series measurements, these components are then quantified theoretically or empirically depending on the complexity of the physical phenomena involved. This paper presents the developments of the newly fine-tuned magnetic field model and evaluates its accuracy, reproducibility and predicting capabilities.
|
|
|
||
| MPPT050 | Test Results for LHC Insertion Region Dipole Magnets | dipole, quadrupole, insertion, octupole | 3106 | ||
|
Funding: U.S. Department of Energy. |
The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) has made 20 insertion region dipoles for the Large Hadron Collider (LHC) at CERN. These 9.45 m-long, 8 cm aperture magnets have the same coil design as the arc dipoles now operating in the Relativistic Heavy Ion Collider (RHIC) at BNL and are of single aperture, twin aperture, and double cold mass configurations. They produce fields up to 3.8 T for operation at 7.56 TeV. Eighteen of these magnets have been tested at 4.5 K using either forced flow supercritical helium or liquid helium. The testing was especially important for the twin aperture models, which have the most challenging design. In these, the dipole fields in both apertures point in the same direction, unlike LHC arc dipoles. This paper reports on the results of these tests, including spontaneous quench performance, verification of quench protection heater operation, and magnetic field quality. Magnetic field measurements were done at 4.5K and at room temperature, and warm-cold correlations have been determined. Some dynamic measurements to study the effect of time decay and snapback at injection were also done, using a fast rotating coil. |
|
||
| MPPT056 | First Ideas Towards the Super-Conducting Magnet Design for the HESR at FAIR | dipole, quadrupole, magnet-design, antiproton | 3354 | ||
|
The Forschungszentrum Juelich has taken the leadership of a consortium being responsible for the design of the HESR going to be part of the FAIR project at GSI. The HESR is a 50 Tm storage ring for antiprotons, based on a super-conducting magnet technology. On basis of the RHIC Dipole D0 (3.6 T), the magnet design for the HESR has started recently. One key issue will be a very compact layout because of the rather short magnets (been 1.82 m for the dipoles and 0.5 m for the other magnets). This paper will present first ideas of the magnetic and cryogenic layout, give a status report on the achievements so far and discuss the need and possible solutions for a bent magnet with a radius of curvature of 13.2 m.
|
|
|
||
| MPPT076 | Conceptual Designs of Magnet Systems for the Taiwan Photon Source | storage-ring, quadrupole, dipole, vacuum | 3979 | ||
|
The National Synchrotron Radiation Research Center (NSRRC) at Taiwan is designing a 3.0 GeV energy with ultra-low emittance storage ring for new Taiwan Photon Source (TPS) project. The storage has a circumference of 514 m with 24 periods of double-bend achromatic magnet system. The conceptual designs for each magnet family for the storage ring are optimize for operation of electron energy at 3.0- 3.3 GeV. This paper reviews the preliminary design and the key accelerator magnet issues.
|
|
|
||
| MPPT086 | Conventional Magnets Design for the Candle Storage Ring | quadrupole, simulation, storage-ring, dipole | 4182 | ||
|
The lattice of 216m long CANDLE storage ring (16 Double Bend Achromat cells) will contain 32 gradient dipole magnets, 80 quadrupole magnets of three types and two types of 64 sextupole magnets. Magnetic as well as mechanical design of those magnets has been performed relying on extensive world experience. Computer simulations and large volume of computations have been carried out to design magnets that conform to strict requirements.
|
|
|
||
| TOAA004 | Field Quality Study in Nb3Sn Accelerator Magnets | dipole, quadrupole, alignment | 366 | ||
|
Funding: This work was supported by the U.S. Department of Energy. |
High field accelerator magnets are being developed at Fermilab for present and next generation hadron colliders. These magnets are designed for a nominal field of 10-12 T in the magnet bore of 40-50 mm and an operating temperature of 4.5 K. To achieve these design parameters, a new, high-performance Nb3Sn superconducting strand is used. Four short Nb3Sn dipole models of the same design based on a single-bore cos-theta coil and a cold iron yoke have been fabricated and tested at Fermilab. Their field quality was measured at room temperature during magnet fabrication and at helium temperature. This paper reports the results of warm and cold magnetic measurements. The systematic geometrical harmonics and their RMS spread due to cross-section imperfections, the coil magnetization effects caused by persistent currents in superconductor and eddy current in the cable, the "snap-back" effect at injection and the iron saturation effect at high fields are presented and compared with theoretical predictions. |
|
||
| TOAA009 | Recent Test Results of the Fast-Pulsed 4 T COSO Dipole GSI 001 | dipole, coupling, synchrotron, injection | 683 | ||
|
For the FAIR-project at GSI a model dipole was built at BNL with the nominal field of 4 T and a nominal ramp rate of 1 T/s. The magnet design was similar to the RHIC dipole with some changes for loss reduction and better cooling. The magnet was already successfully tested in a vertical cryostat with good training behaviour. Cryogenic losses were measured and first results of field harmonics were published. However, for a better understanding of the cooling process quench currents at several ramp rates were investigated. Detailed measurements of the field harmonics at different ramp rates and at several cycles were performed. To separate the effects of the coil and the iron yoke the magnet was disassembled and tested as collared coil only. Recent test results will be presented.
|
|
|
||
| TPAP003 | Exploring a Nonlinear Collimation System for the LHC | collimation, optics, betatron, insertion | 877 | ||
|
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.
|
|
|
||
| TPAP016 | Energy Calibration of the SPS with Proton and Lead Ion Beams | proton, ion, quadrupole, alignment | 1470 | ||
|
The momentum of the 450 GeV/c proton beam of the CERN Super Proton Synchrotron was determined by a high precision measurement of the revolution frequencies of proton and lead ion beams. To minimize systematic errors the magnetic cycle of the SPS had to be rigorously identical for both beams, and corrections due to Earth tides had to be taken into account. This paper presents how the beam momentum was determined from the RF frequency for which the beams are centred in the machine sextupoles. The measured beam momentum is 449.16 ± 0.14 GeV/c for a nominal momentum of 450 GeV/c, and the accuracy is limited by systematic errors.
|
|
|
||
| TPAP024 | Decoupling Schemes for the Tevatron in the Presence of Skew Quadrupole Fields | lattice, quadrupole, dipole, optics | 1850 | ||
|
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. |
|
||
| TPAP029 | Measurements of Field Decay and Snapback Effect on Tevatron Dipole and Quadrupole Magnets | injection, quadrupole, dipole, octupole | 2098 | ||
|
Since the beginning of 2002 an intensive measurement program has been performed at the Fermilab Magnet Test Facility to understand dynamic effects in the Tevatron magnets. Based on the results of this program a new correction algorithm was proposed to compensate for the decay of the sextupole field during the dwell at injection and for the subsequent field "snapback" during the first few seconds of the energy ramp. Beam studies showed that the new correction algorithm works better than the original one, and improves the Tevatron efficiency by at least 3%. The beam studies also indicated insufficient correction during the first 20 s of the injection plateau where an unexpected discrepancy of 0.15 sextupole units of extra drift was observed. This paper reports on the most recent measurements of the Tevatron dipoles field at the beginning of the injection plateau. Results on the field decay and snapback in the Tevatron quadrupoles are also presented.
|
|
|
||
| TPAT065 | Damping Transverse Instabilities in the Tevatron Using AC Chromaticity | simulation, proton, synchrotron, damping | 3665 | ||
|
Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the U.S. Department of Energy. |
Several papers*,** have suggested possibility of using varying chromaticity to damp the head-tail instability. We test this by cycling the chromaticity sextupole magnets in the Tevatron near the synchrotron frequency to see if the head-tail stability threshold is increased. Further we compare the turn-by-turn evolution of a bunch slice in the presence of varying chromaticity to a model previously developed. *W.-H. Cheng, A. M. Sessler, and J. S. Wurtele, Phys. Rev. Lett. 78, 4565 (1997). **T. Nakamura in Proceedings of the 1995 IEEE Particle Accelerator Conference (IEEE, Dallas, 1995), Vol. 5, p. 3100. |
|
||
| TOAB009 | Generation of Short X-Ray Pulses Using Crab Cavities at the Advanced Photon Source | optics, radiation, emittance, simulation | 668 | ||
|
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). |
|
||
| TPPE033 | A Comparison of Electrostatic and Magnetic Focusing of Mixed Species Heavy Ion Beams at NSCL/MSU | focusing, cyclotron, ion, quadrupole | 2281 | ||
|
Funding: This work has been supported by National Science Foundation under grant PHY-0110253. |
Experience at the National Superconducting Cyclotron Laboratory has shown the first focusing element after the electron cyclotron resonance ion source (ECRIS), before the beam is analyzed by a magnetic dipole, to be critical to subsequent beam transport and matching. Until 2004, both ion sources at the NSCL used a solenoid as this first focusing element. Observation of hollow beam formation led to further analysis and the decision to replace the solenoid with an electrostatic quadrupole triplet on a test basis [1]. Substantial increases in net cyclotron output were achieved, leading us to adopt electrostatic quadrupole focusing as the permanent configuration. In addition, a sextupole magnet was installed in this beam line. Motivations for these changes and results of operating experience are discussed. |
|
||
| TPPE054 | Status of the Injection System for the Australian Synchrotron Project | booster, synchrotron, injection, quadrupole | 3271 | ||
|
DANFYSIK A/S designs and builds the complete injection system for the Australian Synchrotron Project. The full-energy booster will accelerate the beam from the injection energy of 100 MeV. to a maximum of 3.0 GeV. The booster is using combined function magnets. The status of the project is presented.
|
|
|
||
| TPPP002 | Global-Beta Measurement and Correction at the KEKB Rings | optics, quadrupole, betatron, closed-orbit | 802 | ||
|
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.
|
|
|
||
| WOAB004 | Applying Frequency Map Analysis to the Australian Synchrotron Storage Ring | resonance, synchrotron, quadrupole, dynamic-aperture | 407 | ||
|
The technique of frequency map analysis has been applied to study the transverse dynamic aperture of the Australian Synchrotron Storage Ring. The results have been used to set the strengths of sextupoles to optimise the dynamic aperture. The effects of the allowed harmonics in the quadrupoles and dipole edge effects are discussed.
|
|
|
||
| WOAB007 | SESAME in Jordan | dipole, synchrotron, vacuum, injection | 586 | ||
|
An overview of the status of SESAME is presented. SESAME (Synchrotron-light for Experimental Science and Application in the Middle East) is an Independent Intergovernmental Organization developed and officially established under the auspices of UNESCO. It involves at the present the following Member States: Bahrain, Egypt, Islamic Republic of Iran, Israel, Jordan, Pakistan, Palestinian Authority, Turkey and United Arab Emirates. Moreover the following States are Observer of SESAME Council: France, Germany, Greece, Italy, Kuwait, Russian Federation, Sweden, UK and United States of America. SESAME will become a major international research center in the Middle East, located in Allan, Jordan. The machine design is based on a 2.5 GeV 3rd generation Light Source with an emittance of 26 nm.rad and 11 straights for insertion devices. The conceptual design of the accelerator complex has been frozen and the engineering design is started. The Phase I scientific program for SESAME has also been finalized and it foresees 6 beamlines. The construction of SESAME building is in progress and the beneficial occupancy is expected by the first half of 2006. The completion of the accelerators complex construction is scheduled for the end of 2009.
|
|
|
||
| WOAC001 | Aberration Correction in Electron Microscopy | electron, quadrupole, multipole, acceleration | 44 | ||
|
The resolution of conventional electron microscopes is limited by spherical and chromatic aberrations. Both defects are unavoidable in the case of static rotationally symmetric electromagnetic fields (Scherzer theorem). Multipole correctors and electron mirrros have been designed and built, which compensate for these aberrations. The principles of correction will be demonstrated for the tetrode mirror, the quadrupole-octopole corrector and the hexapole corrector. Electron mirrors require a magnetic beam separator free of second-order aberrations. The multipole correctors are highly symmetric telescopic systems compensating for the defects of the objective lens. The hexapole corrector has the most simple structure yet eliminates only the spherical aberration, whereas the mirror and the quadrupole-octopole corrector are able to correct for both aberrations. Chromatic correction is achieved in the latter corrector by cossed electric and magnetic quadrupoles acting as first-order Wien filters. Micrographs obtained with aberration-corrected electron microscopes will be shown demonstrating the improvement in resolution to better than 1 Angstroem.
|
|
|
||
| WOAC002 | Chromatically Corrected Imaging Systems for Charged-Particle Radiography | proton, dipole, quadrupole, multipole | 225 | ||
|
In proton radiography, imaging with systems consisting of quadrupole magnets is an established technique for viewing the material distribution and composition of objects, either statically or during fast events such as explosions. With the most favorable magnet configuration, the –I lens, chromatic aberrations generally dominate the image blur. Image resolution can be improved, and largely decoupled from the input-beam parameters, by using a second-order achromatic bend with some additional higher-order aberration correction. The aberration-correction approach is discussed. For a given resolution, such a bend allows use of much lower-energy imaging particles than a –I lens. Each bend design represents a set of equivalent systems; an 800-MeV proton design and its equivalent 40-MeV electron system are presented. The electron system is useful for imaging small objects. Magnet errors in the achromatic bends must be tightly controlled to preserve image quality, but not beyond feasibility of present technology. System performance is verified by particle tracking. Configurations alternative to the canonical achromatic bend are also discussed.
|
|
|
||
| WOAC003 | Effects of Fringe Fields and Insertion Devices Revealed Through Experimental Frequency Map Analysis | storage-ring, undulator, dynamic-aperture, insertion | 266 | ||
|
Funding: This work was supported by the Bundesministerium für Bildung und Forschung and by the Land Berlin. |
Following the pioneering work at the ALS* frequency map analysis was performed at the light source BESSY. With altogether 7 families of sextupole magnets available in the storage ring, amplitude dependent tune shifts can be made rather small. Therefore, the impact of fringe fields of dipole and quadrupole magnets as well as systematic octupole and decapole field components of the quadrupole and sextupole magnets used in addition as horizontal, vertical and skew gradient correctors are clearly visible in the measured maps. Insertion devices with their known systematic and usually unknown random non-linear field components impact the appearance of the frequency maps even more strongly. In the talk the current status of the experiments as well as the results of the theoretical modeling will be presented. *"Global Dynamics of the Advanced Light Source Revealed through Experimental Frequency Map Analysis," D. Robin, et al., Phys. Rev. Lett. 85, 558 (2000). |
|
||
| WOAC007 | Beam-Based Nonlinear Optics Corrections in Colliders | octupole, coupling, multipole, resonance | 601 | ||
|
Funding: Work performed under the auspices of the US Department of Energy |
A method has been developed to measure and correct operationally the non-linear effects of the final focusing magnets in colliders, which gives access to the effects of multi-pole errors by applying closed orbit bumps, and analyzing the resulting tune and orbit shifts. This technique has been tested and used during 3 years of RHIC (the Relativistic Heavy Ion Collider at BNL) operations. I will discuss here the theoretical basis of the method, the experimental set-up, the correction results, the present understanding of the machine model, the potential and limitations of the method itself as compared with other non linear correction techniques. |
|
||
| ROAA002 | CESR-c: Performance of a Wiggler-Dominated Storage Ring | wiggler, resonance, luminosity, betatron | 189 | ||
|
Funding: Work supported by the U.S. National Science Foundation. |
CESR-c operates now as a Wiggler-Dominated Storage Ring extending the lowest operating energy to 1.5GeV/beam. To improve beam stability at low energy, 12 super-ferric wiggler magnets with total length of 15m and 2.1T maximum field were installed in the ring. They cause ~90% of total beam radiation lost and increase radiation damping rate by factor 10 from ~3 to 40 Hz. However, the field of the wiggler magnets not only initiates the radiation, but potentially affects beam dynamics. The latter was an issue of a great concern from the planning the CESR-c project. In this paper we describe general performance of CESR-c and report the results of an experimental study on some aspects of beam dynamics. Comparisons are made between the experimental data and the model prediction. We find that all parameters, which are critically dependent on wigglers, such as beam properties and ring nonlinearity, are in good agreement with those calculated from the model. This validates the ring and wiggler models and justifies our design and production technique of the magnets. The experience we obtained will be extremely useful in future work on linear collider damping rings. |
|
||
| RPAE027 | Linear Optics Measurements in the ESRF Booster | booster, injection, optics, dipole | 1973 | ||
|
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.
|
|
|
||
| RPAE031 | Progress Report on the Construction of SOLEIL | vacuum, quadrupole, power-supply, dipole | 2203 | ||
|
Funding: SOLEIL |
This paper reports the progress achieved in the construction of the accelerators of SOLEIL. Started in January 2002, the construction comes near to its end and the installation of the equipment on the site has begun from September 2004 and shall be completed within one year. The progress on the LINAC and Booster are reported separately, therefore this paper will focus more particularly on the Storage Ring: Dedicated measuring benches have been built to perform the magnetic measurements on all the magnets and the results of measurements have been analysed in term of particle dynamics behaviour in order to prepare the operating point for the commissioning. The status of innovative developments engaged from the beginning as super-conducting RF cavities, NEG coated vacuum chambers and BPMs digital electronics will be described. The construction of the first 6 insertion devices is also well advanced and will be reported. Finally, the machine impedance budget was further evaluated with consequently, still some modifications to the design of some components. |
|
||
| RPAE042 | Optimization of Kicker Pulse Bump by Using a SR Monitor at the Photon Factory | injection, kicker, photon, factory | 2717 | ||
|
We plan to operate the Photon Factory storage ring by top-up injection mode from 2006. To realize this operation mode, remaining coherent oscillation of the stored beam due to error in the injection pulse bump is one of most serious problem. To reducing the error in the injection pulse bump, we calibrated kicking angles of the injection kicker magnets by means of the term by term instantaneous observation of beam profile. We have a SR monitor inside of injection pulse bump. By measureing the tern by tern beam position after the excitation of kicker magnet, we can calibrate the kick angle of the kicker magnet. By using this calibration, we optimized injection pulse bump. As a result, we reduced amplitude of remaining coherent oscillation less than 1/4 of the 1??of the beam size.
|
|
|
||
| RPAE047 | Lattice Study for the Taiwan Photon Source | dynamic-aperture, emittance, lattice, photon | 2989 | ||
|
The feasibility study for the new 3.0~3.3 GeV Taiwan synchrotron light source, dubbed Taiwan Photon Source, was initiated in July, 2004. The goal is to construct a high performance light source with extremely bright X-ray in complementary to the existing 1.5 GeV light source in Taiwan. The ring circumference is 518.4 m and a 24-cell DBA lattice structure is chosen. The natural emittance with distributed dispersion is less than 2 nm-rad. A large booster ring of 499.2 m sharing the storage ring tunnel will be adopted.
|
|
|
||
| RPAE051 | Multipole Design for CAMD Storage Ring | multipole, power-supply, quadrupole, storage-ring | 3161 | ||
|
The CAMD storage ring has been in operation more than 12 years with only sextupole elements in the lattice for correction of nonlinear beam dynamics. To compensate for coupling arising from the integrated effect of skewed elements around the ring, and to improve beam lifetime, a multipole element is required which can be operated in active mode. The design of a magnetic multipole is presented as well as power and control systems designs. The strength and effect and of this element are calculated.
|
|
|
||
| RPAE057 | Dynamic Aperture Optimization for Low Emittance Light Sources | lattice, emittance, dipole, quadrupole | 3378 | ||
|
Funding: Under Contract with the United States Department of Energy Contract Number DE-AC02-98CH10886. |
State of the art low emittance light source lattices, require small bend angle dipole magnets and strong quadrupoles. This in turn creates large chromaticity and small value of dispersion in the lattice. To counter the high chromaticity strong sextupoles are required which limit the dynamic aperture. Traditional methods for expanding the dynamic aperture use harmonic sextupoles to counter the tune shift with amplitude. This has been successful up to now, but is non-deterministic and limited as the sextupole strength increases, driving higher order nonlinearities. We have taken a different approach that makes use of the tune flexibility of a TBA lattice to minimize the lowest order nonlinearities, freeing the harmonic sextupoles to counter the higher order nonlinearities. This procedure is being used to improve the nonlinear dynamics of the NSLS-II lattice. |
|
||
| RPAE059 | Design of 3 GeV Booster for NSLS-II | booster, injection, lattice, dipole | 3473 | ||
|
We present preliminary design of full energy booster for NSLS-II. In the paper we analyze single- and multi-bunch modes of the booster operations. The booster lattice consists of 24 TME cells with two dispersion suppressors. Initial design of the magnets, power supply specifications, Eddy current contribution to the booster chromaticity are discussed.
|
|
|
||
| RPAE072 | Simulations of X-Ray Slicing and Compression Using Crab Cavities in the Advanced Photon Source | emittance, photon, radiation, synchrotron | 3886 | ||
|
Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
Recently, Zholents et al. proposed applying to the Advanced Photon Source an x-ray compression scheme based on a pair of crab cavities and asymmetric cut crystals. We have explored the feasibility and potential performance of this scheme through simulation. We used the code elegant to perform 6-D tracking, allowing us to characterize the emittance growth, which is mostly a result of sextupoles between the cavities. We also explored tolerances on alignment, phase, and voltage of the cavities; lifetime effects; tradeoffs between cavity frequency and voltage; and performance with slicing alone instead of compression. Our conclusion is that sub-picosecond rms x-ray pulse lengths should be feasible. |
|
||
| RPAT053 | Movement of BPMs Due to Thermal Stress in KEKB | pick-up, radiation, luminosity, synchrotron | 3253 | ||
|
Movement of Beam Position Monitors (BPM) due to thermal stress in high beam current operation is observed in KEKB. For high luminosity operation of KEKB, the beam current as high as 1.6A is accumulated in the positron ring and a precise control of the beam orbit based on the BPM system is required. Though the every BPM chamber is fixed firmly on a support of each quadrupole magnet, the BPM chamber moves several hundred microns from the setting position depending on the beam current due to beam pipe heating by strong synchrotron light irradiation. Such movement introduces an unavoidable offset error in the BPM measurement, and is a serious problem not only for KEKB but also for the next generation of B-factory operated with extremely high beam current. We report the measurement of the movement by distance sensors and an attempt to correct the BPM offset error in real-time operation.
|
|
|
||
| RPAT096 | High-Precision Resonant Cavity Beam Position, Emittance and Third-Moment Monitors | quadrupole, dipole, coupling, impedance | 4311 | ||
|
Funding: Work supported by the U.S. Dept. of Energy. |
Linear colliders and FEL facilities need fast, nondestructive beam position and profile monitors to facilitate machine tune-up, and for use with feedback control. FAR-TECH, Inc. is developing a resonant cavity diagnostic to simultaneously measure the dipole, quadrupole and sextupole moments of the beam distribution. Measurements of dipole and quadrupole moments at multiple locations yield information about beam orbit and emittance. The sextupole moment can reveal information about beam asymmetry which is useful in diagnosing beam tail deflections caused by short range dipole wakefields. In addition to the resonance enhancement of a single-cell cavity, use of a multi-cell standign-wave structure further enhances signal strength and improves the resolution of the device. An estimated rms beam size resolution is sub micro-meters and beam position is sub nano-meter. |
|
||
| RPAT098 | Phase-Space Dynamic Tracking by a Two Pickups Data Acquisition System | octupole, lattice, pick-up, kicker | 4326 | ||
|
A two pickups dynamic tracking data acquisition system has been developed at LNF for the DAFNE Phi-factory. Two oscilloscopes sample horizontal and vertical sum and difference signals from two pickups simultaneously; the sampling clock is locked to the DAFNE timing system. A horizontal kick excites the beam motion and initiates the acquisition. Turn-by-turn signals are converted to beam position and stored on a server in a database using timestamp labels. Oscillation amplitude versus time, phase space distribution and frequency domain analysis are shown for several lattices and different settings of sextupoles and octupoles. Results are used to check the DAFNE non-linear model.
|
|
|
||
| RPPP007 | CLIC Damping Ring Optics Design Studies | wiggler, damping, emittance, dynamic-aperture | 1060 | ||
|
In this paper the nonlinearities induced by the short period NbFeB permanent wiggler optimized for the CLIC damping ring and their influence to the beam dynamics are studied.
|
|
|
||
| RPPP047 | Global Optimization of Damping Ring Designs Using a Multi-Objective Evolutionary Algorithm | wiggler, damping, lattice, optics | 2962 | ||
|
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. |
|
||
| RPPP054 | Achieving Large Dynamic Aperture in the ILC Damping Rings | lattice, damping, dynamic-aperture, emittance | 3277 | ||
|
Funding: Work supported by US Department of Energy, Director, Office of Science - Contract Nos. DE-AC03-76SF00098 and DE-AC03-76SF00515. |
The Damping Rings for the International Linear Collider have challenging requirements for the acceptance, because of the high average injected beam power and the large beam produced from the positron source. At the same time, the luminosity goals of the collider mean that the natural emittance must be very small, and this makes it particularly difficult to achieve a good dynamic aperture. We describe a design approach and present a lattice design that meets the emittance specification and has a very promising dynamic aperture. We also discuss the potential impact of the damping wiggler and of magnet errors. |
|
||
| FPAE025 | Study of Slow Beam Extraction Through the Third Order Resonance with Transverse Phase Space Manipulation by a Mono-Frequency RFKO | betatron, emittance, electron, extraction | 1892 | ||
|
An electron pulse-stretcher ring (STB ring) has a function which converts a pulse beam generated by RF linac into a quasi-continuous beam. Circulating beam in the ring is extracted by the third order resonance. Since there is no accelerating field in the ring, the beam approaches a transverse resonance condition due to synchrotron radiation loss with finite chromaticity. The extracted beam from the ring has some spread in time and space corresponding to injected beam from linac even if the injected beam is perfectly matched to the ring optics. However, the extracted beam emittance can be reduced by applying a phase space manipulation using an RF shaker. Under the influence of perturbation using an RF shaker driven by a mono-frequency, the betatron amplitude of circulating beam can be controlled in order to reduce the extracted beam emittance. The experimental results will be reported in this conference.
|
|
|
||
| FPAT079 | Data Base Extension for the Ensemble Model Using a Flexible Implementation | simulation, multipole, quadrupole, space-charge | 4036 | ||
|
Funding: Work supported by DESY, Hamburg. |
To guarantee an adequate design and a proper functionality of various machine components it is of great importance to perform detailed studies of charged particle transport. However, it is often not necessary to initiate individual kinetic simulations. When the evolution of integral quantities is of research interest, it is worth treating an investigated particle ensemble as a whole and applying a macroscopic formulation. Using a collision-less kinetic approach, the simplified model is derived from the well-known Vlasov equation. Instead of solving directly this equation, one can use moments of the density function obtained by means of an averaging process. This formalism had been implemented into the beam dynamics simulation program V-Code and a fundamental database of various beam line elements like cavities, drift spaces, solenoids, quadrupoles and steerers was set up. A flexible realization of the C++ code representing the cavities and the drift spaces can be automatically used for an arbitrary order of moments applying a symbolic algebra program. A useful extension to the remaining beam line elements together with appropriate simulation results is presented in the paper. |
|
||
| FPAT087 | elegantRingAnalysis: An Interface for High-Throughput Analysis of Storage Ring Lattices Using elegant | lattice, dynamic-aperture, storage-ring, simulation | 4200 | ||
|
Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
The code {\tt elegant} is widely used for simulation of linacs for drivers for free-electron lasers. Less well known is that elegant is also a very capable code for simulation of storage rings. In this paper, we show a newly-developed graphical user interface that allows the user to easily take advantage of these capabilities. The interface is designed for use on a Linux cluster, providing very high throughput. It can also be used on a single computer. Among the features it gives access to are basic calculations (Twiss parameters, radiation integrals), phase-space tracking, nonlinear dispersion, dynamic aperture (on- and off-momentum), frequency map analysis, and collective effects (IBS, bunch-lengthening). Using a cluster, it is easy to get highly detailed dynamic aperture and frequency map results in a surprisingly short time. |
|