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| MOPAN004 | Commissioning of the LNLS Elliptically Polarizing Undulator | undulator, storage-ring, controls, betatron | 149 | ||
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We present the results of the commissioning of the first Elliptically Polarizing Undulator to be installed at the 1.37 GeV electron storage ring of the Brazilian Synchrotron Light Source. The undulator is designed to provide UV and soft X-ray photons from 100 eV up to 1 keV with full polarization control. It uses the APPLE II design with 50 mm period and 22 mm gap and allows for both parallel and anti-parallel longitudinal motion of its magnet cassettes. We present the commissioning results including the measured orbit and tune perturbations as well as the non-linear effects of the undulator fields on the stored beam and the corresponding impact on the beam lifetime.
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| MOPAN025 | The Elettra Booster Magnets | dipole, sextupole, booster, quadrupole | 206 | ||
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The third generation light source ELETTRA has been in operation since 1993. A new 2.5 GeV full energy booster injector, that will replace the existing linear injector limited to a maximum energy of 1.2 GeV is now under construction and the commissioning will start this August. The paper reports on the construction of dipole, quadrupole, sextupole and steerer magnets and on the magnetic measurement results with a comparison with the requested specifications.
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| MOPAN084 | Estimating Field Quality in Low-beta Superconducting Quadrupoles and its Impact on Beam Stability | quadrupole, luminosity, collider, superconducting-magnet | 353 | ||
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Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395) |
The aim of this analysis is to study if the field quality in a large aperture low-beta superconducting quadrupole for the LHC upgrade limits the beam performances due to increased geometric aberrations. Random field errors in superconducting quadrupoles are usually estimated by computing the effect of a random positioning of the coil blocks around the nominal position with an r.m.s. of 0.05 mm. Here, we review the experience acquired in the construction of 7 superconducting quadrupoles in the RHIC and in the LHC projects to estimate the precision in the block positioning, showing that there is no visible dependence on the magnet aperture. Different magnet models are then used to estimate the expected field quality in quadrupoles with apertures ranging from 50 to 200 mm. The impact on geometrical aberrations and scaling laws for their dependence on the aperture are finally evaluated. |
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| MOPAN088 | A Large Aperture Superconducting Dipole for Beta Beams to Minimize Heat Deposition in the Coil | dipole, ion, simulation, optics | 365 | ||
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The aim of "beta beams" in a decay ring is to produce highly energetic pure electron neutrino and anti-neutrino beams coming from b-decay of 18Ne10+ and 6He2+ ion beams. The decay products, having different magnetic rigidities than the ion beam, are deviated inside the dipole. The aperture and the length of the magnet have to be optimized to avoid that the decay products hit the coil. The decay products are intercepted by absorber blocks inside the beam pipe between the dipoles to protect the following dipole. A first design of a 6T arc dipole using a cosine theta layout of the coil with an aperture of 80 mm fulfils the optics requirements. Heat deposition in the coil has been calculated using different absorber materials to find a solution to efficiently protect the coil. Aspects of impedance minimization for the case of having the absorbers inside the beam pipe have also been addressed.
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| MOPAN095 | Design of the Precise Unit for the Rotating Coil Measurement System | synchrotron, synchrotron-radiation, quadrupole, coupling | 386 | ||
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A precise rotating coil measurement system (RCS) is developed to characterize the magnetic field quality of the quadrupole (QM) and sextupole (SM) magnets in the Taiwan Photon Source (TPS). A measurement bench is designed to install the magnets easily and mount the rotating coil unit with high reproducibility. The Fiberglass Reinforced Epoxy (FRP) measurement unit (F-unit) exhibits a large sag and mechanical error while it is 880mm long. Therefore, a new graphite measurement unit (G-unit) with a printed circuit coil is adopted to reduce these errors. The rotating coil design and testing using a QM are also described.
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| MOPAN110 | A Technique for High-frequency Scanning of High Power Laser Light for Laser-wire Scanners at Electrons Accelerators | laser, quadrupole, electron, controls | 422 | ||
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Funding: Work supported in part by PPARC LC-ABD Collaboration and the Commission of European Communities under the 6th Framework Programme Structuring the European Research Area, contract number RIDS-011899. |
Electro-optic techniques might allow implementing a laserwire scanner for intra-train scanning at the ILC with scanning speed in excess of 100 kHz. A scanner capable of running at such a rate would in fact provide information about the particle beam size in about one hundred different positions along the bunch train (approximately 1ms long for the ILC*). The design of an electro-optic deflector capable to scan within 10-100 microsecond is presented, discussed and analytically treated.
* ILC Baseline Conceptual Design (2006).: http://www.linearcollider.org/. |
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| MOPAS035 | Rapid-Cycling Dipole using Block-Coil Geometry and Bronze-Process Nb3Sn Superconductor | dipole, synchrotron, injection, coupling | 512 | ||
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Funding: Doe gratn #DE-FG02-06ER41405 |
The block coil geometry utilized in recent high-field dipole development has significant benefit for applications requiring rapid cycling, since it intrinsically suppresses coupling currents between strands. A conceptual design for a 6 Tesla dipole has been studied for such applications, in which the intra-strand losses are minimized by using bronze-process Nb3Sn superconducting wire developed for ITER. That conductor provides isolated fine filaments and optimum matrix resistance between filaments. The block-coil geometry further accommodates placement of He cooling channels inside the coil, so that heat from radiation and from AC losses can be removed with minimum temperature rise in the coil. The design could be operated with supercritical helium cooling, and should make it possible to operate with a continuous ramp rate of 5-10 T/s. |
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| MOPAS055 | Combined Function Magnets Using Double-Helix Coils | dipole, quadrupole, sextupole, focusing | 560 | ||
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We describe a technology for creating easy-to-manufacture combined function magnets. The field is produced by double-helix coils in which the axial path of the windings is defined by a sinusoidal function containing the superposition of the desired multipoles. The magnitude of the superimposed multipoles relative to the main field can be easily controlled to any level. For example, the combined function winding can contain a quadrupole magnet along with the dipole in an easily manufactured, low cost configuration. An example of a 5 T magnet with a main dipole field and a superimposed quadrupole is shown. We discuss the amplitude of the quadruple component and how it effects the maximum dipole field that can be obtained in the coil. We also show how low level (i.e. 0.1% - 1%) modulation amplitudes of superimposed multipoles can be used as built-in or "free" correction coils to compensate for iron saturation effects or geometrically-induced multipoles. An example is shown for a small bend radius (i.e. 718 mm), 100 mm aperture bent dipole in which the bent-yoke-induced quadrupole harmonic is completely corrected by the modulation function of the double helix turns.
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This work is partially supported under U. S. Department of Energy grant : DoE SBIR DE-FG02-06ER 84492 |
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| MOPAS066 | Fast Neutron Radioactivity and Damage Studies on Materials | radiation, radioactivity, permanent-magnet, controls | 581 | ||
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Funding: Work supported by U. S. Dept. of Energy under contracts DE-AC02-76SF00515, DE-AC02-76CH03000 and LCRD DE-FG02-03ER41280. |
Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) to improve reliability and longevity since both accelerator and detectors will be subjected to large fluences of hadrons, leptons and gammas. Examples include NdFeB magnets, considered for the damping rings, injection and extraction lines and final focus, electronic and electro-optic devices to be utilized in detector readout, accelerator controls and the CCDs required for the vertex detector, as well as high and low temperature superconducting materials (LTSMs) because some magnets will be superconducting. Our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented for NdFeB materials at EPAC04 where the damage appeared proportional to the distances between the effective operating point and Hc. We have extended those doses, included other manufacturer's samples and measured induced radioactivities. We have also added L and HTSMs as well as a variety of relevant semiconductor and electro-optic materials including PBG fiber that we studied previously only with gamma rays. |
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| TUPMN004 | Final Adjustment of the Magnetic Field of the LNLS VUV Undulator. | undulator, radiation, insertion, insertion-device | 917 | ||
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The first insertion device built at LNLS was an elliptically polarized undulator, designed to cover the vacuum ultraviolet and the soft X-ray spectrum. Its magnetic characterization was done using two techniques: Hall probes, for local field measurements, and rotating coil, operating in a way similar to flip-coil, to determine the integrated multipoles. Final results for the phase errors as well as the procedures used to correct the integrated multipoles are presented.
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| TUPMN006 | Apple-II and TESLA FEL Undulators at Danfysik A/S | undulator, insertion-device, insertion, electron | 923 | ||
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Danfysik A/S* has recently designed and produced a high-performance Apple-II type insertion device for the Australian Synchrotron Project, with low variation of the first integrals versus gap and phase, and minimal phase error. Thanks to software assistance, and an unconventional keeper design, the total time spent on magnet mounting, shimming and final magnetic testing was reduced to 5 weeks. Furthermore, in order to negate the second-order tune effect of the insertion device on the dynamic aperture, ESRF-type tune shims were designed and installed. Danfysik is manufacturing and assembling one of three undulator prototypes for the TESLA FEL project at DESY. The prototype is based on a design made by DESY, but with changes implemented by Danfysik. A major part of the project is to make an industrial study that will recommend where design efforts on the next prototype generation shall be focused.
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* http://www.danfysik.com/ |
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| TUPMN013 | Dynamic Multipole Shimming of the APPLE Undulator UE112 | undulator, simulation, permanent-magnet, dynamic-aperture | 941 | ||
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The dynamic off axis field integrals of the BESSY UE112 are of the order of 3 Tmm. They reduce the dynamic aperture significantly which is not tolerable for top-up operation. The dynamic multipoles have successfully been shimmed for the elliptical mode using distributed Fe-shims. In the inclined mode the multipoles are minimized actively with rotatable permanent magnets which are adjusted dependent on gap and phase position. The dynamic properties of the unshimmed and the shimmed device have been simulated using an analytic model for the field description and a generating function algorithm for tracking.
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| TUPMN057 | Design and Tuning of NSRL Undulator UD-1 | undulator, radiation, sextupole, quadrupole | 1055 | ||
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The design, construction, and tuning of the first undulator UD-1 in NSRL are described. The magnetic field design and requirement are given. The results of the magnet blocks measurement and the magnetic field tuning by interchanging magnet blocks are presented.
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| TUPMN070 | Magnet Block Arrangements for the Apple-II Elliptically Polarized Undulator | polarization, undulator, photon, storage-ring | 1079 | ||
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The good field region (magnetic field roll-off) of the horizontal and vertical field distribution in the elliptically polarized undulator (EPU) of the APPLE II structure is too short. Meanwhile, the strong force variation will be created between the magnet arrays on different phase. Hence, a magnet block was magnetized with an tilt angle has been studied to enlarge the good field region and a different arrangement of magnet block module is used to reduce the force variation. In addition, the pure and hybrid structure of the EPU with different end pole design has been studied. This study will obtain a small variation of the first and second field integral on different gap and phase. This work will report the scheme of the magnet block arrangement and the end pole design for the APPLE II elliptically polarized undulator.
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| TUPMS024 | Development of a 100 mm Period Hybrid Wiggler for the Australian Synchrotron Project | wiggler, electron, synchrotron, background | 1233 | ||
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Funding: Australian Synchrotron Project |
This paper summarizes the final magnetic measurement for a hybrid wiggler installed at the Australian Synchrotron Project (ASP). This device uses an anti-symmetric, hybrid design with a period of 100 mm and 40 full-strength Vanadium-Permendur poles surrounded by Neodynium-Iron-Boron magnets. It is designed to operate at two gaps with critical energies of 11.4 (14mm) and 9.6 keV (18.16mm) and to have a maximum gap with the field strength By ≤ 50 G. The wiggler's drive mechanism is capable of moving from minimum to maximum gap in 96 seconds. End terminations are designed to maintain the electron trajectory on-axis. The straightness of the electron orbit is controlled by moving the poles vertically and horizontally. The integrated multipoles are controlled over the interval |x| < 25 mm and all gap sizes by moving the side magnets, installing correction magnets at the wiggler entrance and exit and using correction coils. All adjustments have been made using threaded fasteners. No shims have been used. |
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| TUPAN001 | Analytic Models for Quadrupole Fringe-Field Effects | quadrupole, focusing, dipole, proton | 1386 | ||
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Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada |
The linear-field non-scaling FFAG lattices originally proposed for multi-GeV muon acceleration are now being modified for application to order 100 MeV/u proton or carbon medical applications. The momentum range is large and the chromatic tune variation is significant. In the medical case, the time of flight variation is immaterial but the issue of resonance crossing is more acute owing to the much lower rate of energy gain. Magnets with non-normal entry/exit faces are considered as means to reduce the tune variation. Thus one is motivated to study fringe fields and their effects. We make a brief study of dipole and quadrupole magnets with normal and rotated entry/exit faces. For the artificial case of a cosine-squared fall off in the quadrupole field, analytic results are obtained which though approximate are superior to numerical integration. This property is achieved by insisting that the error in the equation of motion is zero and the determinant is unity at the entry, exit and centre of the fringe field. |
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| TUPAN035 | Reduction of the Non-Linearities in the DAPHNE Main Rings Wigglers | wiggler, octupole, simulation, quadrupole | 1463 | ||
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The wigglers of the DAPHNE main rings have been the main source of non-linearities for the beam dynamics in the collider. This paper describes a method to reduce the integrated odd multipoles (the even ones tend to vanish for the periodicity of the magnet) by alternatively displacing the magnetic axis of the poles to compensate the integrated odd multipoles in each half-period of the wiggler. In order to check the effectiveness of this approach, tracking studies have been performed. Tracking results have been used to tune the MAD model of the wiggler.
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| TUPAN090 | Parametric Field Modelling for the LHC Main Magnets in Operating Conditions | quadrupole, dipole, injection, extraction | 1586 | ||
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The first injections and ramps in the LHC will require a prediction of the settings of the main ring powering circuits as well as the main correctors. For this reason we are developing a parametric model of the magnetic field generated by the LHC magnets that will provide the field dependence on current, ramp-rate, time, and history. The model of the field is fitted on magnetic field measurements performed during the acceptance tests in operating conditions before their installation in the machine. In this paper we summarise the different steps necessary to select the relevant data and identify the parameters: the data extraction, the cleaning and the validation of the measurements, and the fitting procedure that is used to obtain the parameters from the experimental results. The main result reported is a summary of the value of the parameters obtained with the above procedure, and describing the behaviour of the magnetic field in the LHC main superconducting magnets (i.e. arc, dispersion suppressors and matching sections).
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| TUPAS017 | Tune Drifts on the Tevatron Front Porch | dipole, sextupole, coupling, quadrupole | 1691 | ||
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Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy. |
Measurements of the tune on the front porch of the Tevatron* showed a drift of the tune which tracked the time dependence of the sextupole moment in the dipoles. Calculations using survey data to calculate the closed orbit failed to reproduce the observed tune shifts. The feed down of these sextupole moments generates a quadrupole field at the ends of the dipoles. It is suggested, based on calculations, that the change in the sextupole moment of the dipoles also produces a change in the strength of the strength of the zero length quadrupole incorporated in the end of the dipoles and that this change can account for the observed tune drifts.
*Tevatron Chromaticity and Tune Drift and Snapshot Studies Report, G. Annala, P. Bauer, M. Martens, D. Still, G. Velev, Beams-doc-1236 (Jan. 5,2005) |
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| THPMS053 | Compensation of the Effect of a Detector Solenoid on the Beam Size in the ILC | simulation, electron, dipole, quadrupole | 3109 | ||
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In the International Linear Collider (ILC) [1] the colliding beams must be focused to the nanometre size in order to reach the desired luminosity. The method of Weak Antisolenoid is used for the compensation of the effect of the Detector Solenoid on the beam size [2, 3]. The studies of this method require the computer simulation of the charged particle's kinematics in the arbitrarily distributed solenoidal, dipole, quadrupole and higher multipole fields. We suggest the mathematical algorithm that allows to optimize parameters of antisolenoid for different configurations of Final Focus magnets and to compensate parasitic effects of the Detector Solenoid on the beam.
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[1] 'International Linear Collider Reference Design Report', April 2007 |
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| THPAN003 | Image Effects on the Transport of Intense Beams | focusing, simulation, beam-transport, vacuum | 3223 | ||
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Funding: CNPq and FAPERGS, Brazil, and U. S. AFOSR Grant No. FA9550-06-1-0345. |
We start by analyzing the image effects of a cylindrical conducting pipe on a continuous beam with elliptical symmetry. In particular, we derive an exact expression for the self-field potential of the beam inside the pipe without using any sort of multipole expansion. By means of a variational method, the potential for beams with varying density profiles along an elliptical shape is used to search for equilibrium solutions for intense beams. For that, we assume a uniform focusing in the smooth-focusing approximation. A curious result is that the product of the rms sizes along the ellipsis semi-axis stays constant as the pipe radius is varied. Finally, we prove that despite the nonlinear forces imposed by the image charges of an arbitrary shape conducting pipe, intense beams in uniform focusing fields preserve a uniform density in the equilibrium. |
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| THPAN019 | Utilizing a Wien Filter within the Beam Dynamics Simulation Tool V-Code | simulation, dipole, electron, extraction | 3265 | ||
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Funding: This work was partially funded by EUROFEL (RIDS-011935), DESY Hamburg, and DFG (SFB 634). |
Beam dynamics simulations for computationally large problems are challenging tasks. On the one hand, to accurately simulate the electromagnetic field distribution within the whole device and the surrounding environment it is essential to consider all necessary device components including even small geometry details, complicated material distributions and the field excitations. On the other hand, further computational effort has to be put into precise modeling of the injected particle beam for detailed beam dynamics simulations. Under linear conditions, it is possible to separate the field calculation of the device from the computation of the particles self-field which can result in the proper application of diverse numerical schemes for the individual field contributions. In the paper it is demonstrated how the static electric and magnetic fields of a Wien filter beam line element can be treated as applied external fields within the beam dynamics simulation tool V-Code under the assumption that the interaction of the particle beam with the surrounding materials can be neglected. |
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| THPAN027 | The Optimum Chromaticity Correction Scheme for Monochromatic and Non-Monochromatic Beam in HESR | sextupole, lattice, quadrupole, octupole | 3286 | ||
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The High Energy Storage Ring (HESR) of FAIR project consists of two achromatic arcs and two dispersionless straight sections. Due to the multi-functional purpose of the straight sections their contribution into the total chromaticity of the first and second order exceeds the arc's contribution and can affect on the non-monochromatic beam dynamic aperture. We investigate the optimum sextupole and octupole correction scheme for monochromatic and non-monochromatic beam to reach the larger dynamic aperture.
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| THPAN033 | Design Study of the Dipole Magnet for the RHIC EBIS High Energy Transport Line | dipole, quadrupole, sextupole, simulation | 3301 | ||
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The design studies of the dipole magnet for EBIS HEBT line is proceeding. The RHIC EBIS is a new high current highly charged heavy ion preinjector for RHIC. The dipole magnet discussed in this paper will be used to guide the beam to existing heavy ion injection line to Booster. A total of 145 degrees bend is provided by two identical dipole magnets with a slit between these magnets to pass only intended charge state ions. Also this magnet has a hole in the side wall to pass the beam from the existing Tandem Van de Graaff. The performance of this magnet calculated by TOSCA and the results of the particle tracking calculation are described.
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| THPAN068 | Wakefield Models for Particle Tracking Codes | simulation, dipole, quadrupole, collective-effects | 3378 | ||
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Wakefields have a considerable effect on beam dynamics and they must not be neglected for emittance growth studies, background estimates and other problems. The codes used for these problems are normally not capable of self-consistent wakefield calculations. They should thus be extended with either analytical models or export the wakefields numerically evaluated with other codes (such as Gdfidl) when analytical models are not feasible. We discuss both approaches and present their implementation in PLACET, MERLIN and BDSIM. The simulation results for the ILC and CLIC beam delivery systems are given as an example. Results produced with different codes are compared.
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| THPAS103 | Design of a Thin Quadrupole to be Used in the AGS Synchrotron | quadrupole, sextupole, simulation, acceleration | 3723 | ||
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Funding: Work supported by the US Department of Energy |
The AGS synchrotron employs two partial helical snakes* to preserve the polarization of the proton beam during acceleration in the AGS. The effect of the helical snakes on the beam optics is significant at injection energy, with the effect greatly diminishing early in the acceleration cycle. In order to compensate for the effect of the snakes on the beam optics, we have introduced eight compensation quadrupoles in straight sections of the AGS at the proximity of the partial snakes. At injection the strength of these eight quads is set at a high value but ramped down to zero when the effect of the snakes diminishes. Four of the compensation quadrupoles had to be placed in very short straight sections therefore had to be 'thin' with a length of ~30 cm. The 'thin' quadrupoles were laminated and designed to minimize the strength of the dodecoupole harmonic. The thickness of the lamination was also calculated** to keep the ohmic losses generated by the eddy currents in the laminations below an acceptable limit. Comparison of the measured and calculated harmonics will be presented and the ohmic losses due to the eddy currents, as a function of time during rumping will be discussed.
* H. Huang, et al., Proc. EPAC06, (2006), p. 273.** OPERA computer code. Vector Fields Inc. |
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| FRPMN011 | Studies of Dipole Field Quality for the Beta-Beam Decay Ring | dynamic-aperture, dipole, sextupole, resonance | 3904 | ||
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Funding: European Community under the FP6 - Research Infrastructure Action - Structuring the European Research Area - EURISOL DS Project Contract no. 515768 RIDS. |
The aim of the beta-beams is to produce highly energetic beams of pure electron neutrino and anti-neutrino, coming from beta-decays of the 18Ne10+ and 6He2+, both at γ=100, directed towards experimental halls situated in the Frejus tunnel. The high intensity ion beams are stored in a ring until the ions decay. The beta decay products have a magnetic rigidity different from the one of the parent ions and are differently deflected in the 6T superconducting dipoles. Consequently, all the injected ions are lost anywhere in the ring, generating a high level of irradiation. So, the dipole apertures need to be large enough to avoid the decay products hitting their walls, which may worsen the field quality. A study on its tolerances has been carried out. Since the decay ring has to accept the beam during a large number of turns, the chosen criteria is the size of the dynamic aperture that the multipolar defects in the dipoles may shrink. Tolerances on the systematic and random errors of these defects have been investigated. In order to relax the tolerances, a routine was written which enlarges automatically the dynamic aperture in presence of field errors. |
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| FRPMN019 | The Regular and Random Multi-Pole Errors Influence on the HESR Dynamic Aperture | sextupole, lattice, quadrupole, octupole | 3949 | ||
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The High Energy Storage Ring has the racetrack lattice, where each arc has the even number of super-periods S and the tune with one unit smaller ν=S-1 in both planes. Due to this fundamental feature the total n-order multi-pole is entirely cancelled and the regular errors can be fully compensated inside of one arc. In case of the random multi-pole errors the dynamic aperture is determined by the structure resonances excitation. We consider both regular and random multi-pole influence on the dynamic aperture and the possible correction scheme.
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| FRPMN078 | Improved Algorithms to Determine Non-Linear Optics Model of the SPS from Non-Linear Chromaticity | injection, octupole, simulation, optics | 4231 | ||
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Funding: This work is partially supported by the U. S. DOE |
In recent years several measurements of the SPS non-linear chromaticity have been performed in order to determine the non-linear optics model of the SPS machine at injection energy for different cycles. In 2006 additional measurements have been performed at injection and during the ramp for the cycle used to accelerate the LHC beam. New and more robust matching algorithms have been developed in 2006 to fit the model to the measurements up to arbitrary chromatic order. In this paper we describe the algorithms used in the analysis of the data and we summarize and compare the results from all experiments. |
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| FRPMS097 | Realistic Non-linear Model and Field Quality Analysis in RHIC Interaction Regions | dipole, quadrupole, sextupole, interaction-region | 4309 | ||
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Funding: Work performed under the United States Department of Energy Contract No. DE-AC02-98CH1-886. |
The existence of multipolar components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. So, a realistic non-linear model is crucial for understanding the beam behavior and to achieve the ultimate performance in RHIC. A procedure is developed to build a non-linear model using the available multipolar component data obtained from measurements of RHIC magnets. We first discuss the measurements performed at different stages of manufacturing of the magnets in relation to their current state in RHIC. We then describe the procedure to implement these measurement data into tracking models, including the implementation of the multipole feed down effect due to the beam orbit offset from the magnet center. Finally, the field quality analysis in the RHIC interaction regions is presented. |
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| FRPMS111 | Dynamic Aperture Evaluation at the Current Working Point for RHIC Polarized Proton Operation | dynamic-aperture, sextupole, resonance, dipole | 4363 | ||
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Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH10886. |
To further improve the the polarized proton (pp) luminosity in the Relativistic Heavy Ion Collider, the beta functions at the two interaction points (IPs) will be reduced from 1.0 m to 0.9m in 2007. In addition, it is planned to increase the bunch intensity from 1.5*1011 to 2.0*1011. To accommodate these changes, the nonlinear chromaticities and the third resonance driving term should be corrected. In 2007, the number of the arc sextupole power supplies will be doubled from 12 to 24, which allows nonlinear chromaticity correction. With the updated field errors in the interaction regions (IRs), detailed dynamic aperture studies are carried out to optimize the nonlinear correction schemes, and increase the available tune space in collision. |
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