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WEPC004 | Design Status of the Taiwan Photon Source | booster, lattice, emittance, storage-ring | 1986 | ||
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We report updated design works for a new 3-3.3 GeV synchrotron light source called Taiwan Photon Source (TPS). The lattice type of the TPS is a 24-cell DBA structure and the circumference is 518.4 m. The injector booster will be housed in the same tunnel. We present the lattice design, the accelerator physics issues and its expected performances.
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WEPC024 | Low Beta Structure for the ANKA Storage Ring | optics, emittance, vacuum, injection | 2034 | ||
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The ANKA storage ring has a fourfold symmetry with a double DBA structure. Four (~1.7 m) straight sections are used for the RF and the injection. Four sections (~ 4.5 m) are used for insertion devices (three installed). The beta functions in these sections are 14, respectively 7 m (horizontal/vertical). This is not ideal for small gap (7 mm) insertion devices. Reducing the vertical beta function to 2 m is possible with the present magnet configuration and is done for special user operation. Reducing both the horizontal and vertical beta function is favoured for one future beam line. This will afford a change of the present magnet configuration. Different options have been calculated and will be discussed.
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WEPC045 | Alternative Lattice Settings for ALBA Storage Ring | sextupole, lattice, optics, resonance | 2088 | ||
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ALBA is a 3 GeV synchrotron light source under construction in Spain. The lattice for the standard operational mode is based in a DBA-like structure, with finite dispersion in the straight sections and extra space in the arcs. This solution provides small emittance with a large available space for insertion devices, RF and diagnostic components, and large dynamic aperture and energy acceptance. Other optic modes has been investigated, in order to facilitate the commissioning procedure or to provide different operating modes to the users: pure achromatic lattice, without dispersion in the straight section; achromatic arcs, where the dispersion is zero in the long straight; or a relaxed lattice, offering higher emittance. This paper review the performance of this alternative options, including the non-linear performance.
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WEPC056 | Emittance Reduction by Longitudinally Varying Dipole Field | emittance, dipole, optics, radiation | 2118 | ||
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One of the most important matters for synchrotron radiation source is decreasing the beam emittance to increase the brightness. The electron beam emittance is almost determined by electron energy and the average H-function. For further improvement of the emittance, we can change the damping partition number by radially varying dipole field and can reduce the emittance. However, this method is not effective for a small emittance lattice due to its small dispersion function. We have studied the emittance reduction by longitudinally varying magnetic field in a bending magnet. The radius of curvature is assumed to vary with the function of nth degree (n=1,2,3,4). The emittance is calculated numerically for minimum emittance and achromat configuration. In this paper, we describe the details of calculated results and discuss the effectiveness of the method.
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WEPC059 | Lattice Design of PEP-X as a Light Source Machineat SLAC | wiggler, emittance, injection, sextupole | 2127 | ||
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The lattice study for converting the High Energy Ring (HER) of PEP-II into a light source machine with minimal modifications is reported. In this design, a higher phase advance is used in the HER FODO lattice which reduces the emittance to 5 nm at 4.5 GeV without a damping wiggler, and to 0.4 nm with 116 m damping wiggler included in two straight sections out of six. We also study the possibility of replacing one of the six FODO arcs with eight DBA cells to provide additional dispersion free straight sections for the experimental beam lines. The DBA cells will reuse the existing HER and LER (Low Energy Ring) magnets for a minimal cost of the modification. The main parameters and beam dynamics properties of these lattices are presented.
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WEPC097 | Active Shimming of the Dynamic Multipoles of the BESSY UE112 APPLE Undulator | multipole, injection, undulator, electron | 2222 | ||
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APPLE undulators produce strong dynamic multipoles in the elliptical and inclined mode which can significantly reduce the electron beam dynamic aperture. The multipole strength scales with the square of the period length and the inverse of the electron energy. A large horizontal dynamic aperture is essential for top up operation. For the BESSY devices the dynamic multipoles generated in the elliptical mode have efficiently been compensated with iron shims. For the inclined mode no passive compensation scheme is available. In case of the strong BESSY 112mm APPLE device flat current wires have been glued onto the undulator chamber, which permit the cancellation of arbitrary multipoles. The full horizontal dynamic aperture has been recovered in the inclined mode. Tracking simulations and measurements of the electron beam performance for uncompensated and compensated dynamic multipoles will be presented.
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WEPC117 | Influence of Insertion Devices on the ALBA Dynamic Aperture | wiggler, undulator, lattice, betatron | 2279 | ||
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Insertion devices can produce effects reducing the dynamic aperture in a storage ring. To study these effects for the ALBA light source the following insertion devices were inserted in the ALBA lattice: a superconducting wiggler SC-W31 with 31-mm-period and 2.1-T-field amplitude, and two Apple-II type PMM NdFeB undulators with periods of 62 mm (HU62) and 71 mm (HU71). Results of numerical study of the nonlinear beam dynamics by a 6D computer code are presented.
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WEPP012 | Analysis of Optical Layouts for the Phase 1 Upgrade of the CERN Large Hadron Collider Insertion Regions | optics, insertion, quadrupole, dipole | 2551 | ||
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In the framework of the studies for the upgrade of the insertions of the CERN Large Hadron Collider, four optical layouts were proposed with the aim of reducing the beta-function at the collision point down to 25 cm. The different candidate layouts are presented. Results from the studies performed on mechanical and dynamic aperture are summarized, together with the evaluation of beam-beam effects. Particular emphasis is given to the comparison of the optics performance, which led to retain two promising layouts for further investigation and development.
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WEPP018 | Operational Experience with a Near-integer Working Point at RHIC | proton, background, closed-orbit, heavy-ion | 2563 | ||
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During the RHIC polarized proton run in FY 2006 it became evident that the luminosity performance is limited by the beam-beam effect. With a working point between 2/3 and 7/10, and the necessity to mirror the tunes of the two RHIC rings at the diagonal, the beam with a horizontal tune closest to 2/3 showed poor lifetime. To overcome this limitation, a near-integer working point has been proposed. Tracking studies performed at both working points showed a larger dynamic aperture near the integer tune than above 2/3. In Run-8, this new working point was commissioned in one ring of RHIC, while the other ring was operated at the same working point as in Run-6. In this paper we report the commissioning process and operational experience with this new working point.
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WEPP024 | Non-linear Correction Schemes for the Phase 1 LHC Insertion Region Upgrade and Dynamic Aperture Studies | resonance, quadrupole, optics, insertion | 2569 | ||
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The Phase 1 LHC Interaction Region (IR) upgrade aims at increasing the machine luminosity essentially by reducing the beam size at the Interaction Point (IP). This requires a total redesign of the full IR. A large set of options have been proposed with conceptually different designs. This paper reports on a general approach for the compensation of the multipolar errors of the IR magnets in the design phase. The goal is to use the same correction approach for the different designs. The correction algorithm is based on the computation of the IR transfer map. Its performance is tested using the dynamic aperture as figure of merit.
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WEPP116 | Muon Decay Ring Study | emittance, closed-orbit, quadrupole, storage-ring | 2770 | ||
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Three different muon decay ring configurations are being considered for a neutrino factory. A racetrack design is the current ISS baseline (as it allows greater flexibility in the choice of detector sites) but triangular and bow-tie rings have advantages in neutrino production rates*. Using tracking code simulations, a study of the latter two designs is carried out. Since spin depolarisation measurements have been proposed for muon energy calibration**, spin tracking is included in this study. Dynamic aperture is important and is also calculated.
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*International Scoping Study report, 2006. |
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THPC011 | The CR-RESR Storage Ring Complex of the FAIR Project | extraction, antiproton, injection, quadrupole | 2996 | ||
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In frame of the FAIR project (at GSI, Germany) the CR-RESR storage ring complex has been designed for efficient cooling, accumulation and deceleration of antiproton and rare isotopes beams. The complex consists of the Collector Ring (CR) and the accumulator / decelerator ring RESR. The large acceptance CR will be operated at three different optical modes, two of them providing fast pre-cooling of antiprotons and rare isotopes. This ring will be also used as an instrument for mass measurements of very short-lived nuclei when tuned to an isochronous mode. The RESR will be used as accumulator of the antiprotons by means of the stochastic cooling technique and as a decelerator of rare isotopes. The structure of the CR and RESR lattices and its ion optical properties are described in this contribution. The beam dynamics of these rings at different operation scenario are discussed.
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THPC025 | Further Advances in Understanding and Optimising Beam Dynamics in the Diamond Storage Ring | quadrupole, lattice, coupling, storage-ring | 3032 | ||
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We report the results of recent beam dynamics studies of the Diamond storage ring. These studies were aimed at both improving our understanding of the machine operation as well as establishing a reliable, well corrected lattice with long lifetime and high injection efficiency suitable for later top-up operation. Particular attention has been given to measuring and controlling the linear optics of the lattice, to determining the various contributions to the overall beam lifetime and to optimising the sextupole strengths for good on and off momentum dynamic aperture. For each topic, detailed comparisons with model predictions are also described.
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THPC055 | Dynamic Aperture Studies for PETRA III Including Magnet Imperfections | multipole, wiggler, lattice, damping | 3107 | ||
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PETRA III is a 3rd generation synchrotron radiation light source. Efficient injection in the top up mode requires a dynamic aperture of 30 mmmrad or larger, while a 2 hour Touschek lifetime needs an average momentum aperture of around 1.5 %. We present studies on the impact of recently measured magnet imperfections on the available dynamic aperture. To this end, tracking simulations have been performed including the effects of measured multipole errors of lattice magnets and of 20 four-meters-long damping wigglers.
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THPC057 | Field Interference of Magnets in the Large Acceptance Storage Ring CR of the Fair Project | dipole, quadrupole, multipole, simulation | 3113 | ||
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The large acceptance storage ring CR is planned to be used for accumulation and cooling of rare isotope and antiproton beams at the future FAIR accelerator facility. The huge apertures as well as the close arrangement of the dipoles and quadrupoles make overlapping between the end fields of the magnets unavoidable. In addition, corrector magnets are planned to be installed in the drift sections between the dipoles and quadrupoles for closed orbit corrections. The presence of additional iron can have a significant influence on the magnetic field distribution. This interference can lead to a reduction of the integral field quality decline that is undesirable since it can affect the beam dynamics. In this contribution we present the results of 3D magnetic field simulations performed using the OPERA computer code. The field maps were derived and further analyzed. The corresponding sets of multipole components were calculated and were then implemented into one of the codes for the beam dynamics calculations. The MAD code was used to calculate the dynamic aperture and to estimate the effect of the field interference on the beam dynamics of the ring.
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THPC059 | Studies of Wire Compensation and Beam-beam Interaction in RHIC | simulation, emittance, beam-losses, luminosity | 3119 | ||
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Beam-beam interaction is one of the dominant source of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and the principle is now being experimentally investigated at RHIC. In this paper, we use simulations to study the effectiveness of wire compensation based on tune footprints, diffusive apertures, and beam loss rates using a parallel weak-strong beam simulation code (BBSIM). In addition we extensively study the diffusion properties of RHIC beams for different beam and wire parameters. Beam-beam effects on emittance growth are investigated through the solution of the diffusion equation for the transverse action variables.
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THPC062 | Multi-Particle Weak-Strong Simulations of RHIC Head-on Beam-Beam Compensation | emittance, simulation, proton, electron | 3125 | ||
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An electron beam has been proposed in the Relativistic Heavy Ion Collider (RHIC) to compensate beam-beam effects in polarized proton collisions. This electron beam will collide head-on with the proton beam. Using the weak-strong beam-beam interaction model, we have carried out six-dimensional multiparticle simulations to investigate the effects of head-on beam-beam compensation. Beam lifetime, transverse emittances, and luminosity are calculated for cases with and without beam-beam compensation for up to 10 million turns. The migrations of particles between different actions and the beam spectrum are also calculated.
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THPC067 | ALBA Dynamic Aperture Optimization | resonance, sextupole, lattice, betatron | 3140 | ||
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The lattice of ALBA, the 3 GeV synchrotron light source in Spain, provides extremely low emittance of the beam. It is known that such lattices require strong sextupole magnets to compensate natural chromaticities. The paper describes strategy and results of the ALBA dynamic aperture optimization including both tune point selecting and sextupoles arrangement to increase the DA size.
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THPC068 | Effect of Magnetic Multipoles on the ALBA Dynamic | sextupole, multipole, quadrupole, dipole | 3143 | ||
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For modern synchrotron light sources the main limitation of dynamic aperture is due to the strong chromatic sextupoles. However, small multipole errors in magnetic elements can reduce the original dynamic aperture by generating high order resonances at the aperture boundary. For the ALBA synchrotron light source a dynamic aperture in the presence of magnetic multipoles in the main magnets was simulated by tracking code. Both systematic and random magnetic errors were taken into account. In this paper we report on the results of our considerations.
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THPC070 | Symmetry Restoration of the SPring-8 Storage Ring by Counter-sextupole Magnets | sextupole, electron, lattice, betatron | 3149 | ||
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In the SPring-8 storage ring there are four magnet-free long straight sections of about 30m. These were realized in 2000 by locally rearranging quadrupole and sextupole magnets. In modifying the optics we took care of the periodicity of cell structure, especially of sextupole field distribution along the ring. To keep the periodicity high and hence the dynamic aperture large, we adopted a scheme in which "betatron phase matching" and "local chromaticity correction" are combined. In this scheme the dynamic aperture for on-momentum electrons is kept by the phase matching and that for off-momentum electrons is enlarged by the local chromaticity correction with weak sextupoles (SL). After modifying the lattice, we tried to recover the symmetry of the ring further and found that a harmful effect of nonlinear kick due to SL can be minimized by additional "counter-sextupole magnets" placed 180 degrees apart in horizontal betatron phase from SL. We installed such counter-sextupoles in every long straight sections and confirmed that the aperture was improved. In the paper we discuss these topics showing experimental data of injection efficiency, momentum acceptance, etc.
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THPC080 | The VEPP-4M Dynamic Aperture Determination with Beam-beam Effects | beam-beam-effects, simulation, collider, insertion | 3170 | ||
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To determine experimentally the particle stable area under the influence of beam-beam effects in the electron-positron collider VEPP-4M we measure the beam lifetime with high accuracy as a function of moving aperture. The measurement is performed by a photodiode installed in the collider diagnostic beam line. The experimental setup and the measurement results are described. Comparison with the tracking simulation is presented.
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THPC081 | RF Wire Compensator of Long-range Beam-beam Effects | coupling, emittance, simulation, beam-beam-effects | 3173 | ||
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The dynamic aperture of the proton beam circulating in the Large Hadron Collider (LHC) is expected to be limited by up to 120 long-range beam-beam encounters. In order to perfectly compensate the LHC long-range beam-beam effect for nominal as well as for so-called 'PACMAN' bunches, i.e. bunches at the start or end of a bunch train, the wire compensator strength should be adjusted for each bunch individually. Here an RF-based compensator is proposed as a practical solution for the PACMAN compensation. We show that this approach also allows relaxing the power and precision requirements compared with those of a pulsed DC device, to a level within the state-of-the-art of RF technology. Furthermore it allows the use of a passive circulator in the tunnel close to the beam and thus a significantly reduction of the transmission line length and of the resulting multiple reflection issues. Simulations, issues related to RF phase noise and first experimental results from laboratory models as well as from a wire-compensator prototype installed in the CERN Super Proton Synchrotron (SPS) are presented.
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