| Paper | Title | Page |
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| TUPPC001 | Quadrupole Shapes | 1149 |
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| Traditionally, quadrupoles are shaped to have a constant vertical cross-section. In other words, the poles are cylindrical segments extended in the beam direction and circular or hyperbolic in cross section. At the ends, the poles are simply truncated or sometimes slightly smoothed with a chamfer. Even very short quadrupoles are often this shape. A new shape is derived analytically, and it is demonstrated that this shape yields dramatically smaller aberrations. | ||
| TUPPC003 | Analytical Methods for Statistical Analysis for the Correction of Coupling Due to Errors | 1152 |
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| The statistical evaluation of the coupling induced by magnets errors and misalignments on the optics design of a machine are done by tracking and Monte Carlo methods. These techniques are CPU demanding and time consuming. During the preliminary optics design phase a faster technique can be useful to evaluate the order of magnitude and the effectiveness of the correction system. Analytical expression for the transport along the machine of the magnets errors and misalignment are derived at first order. A perturbative approach is used to take into account the effect of a non zero central trajectory in the multipoles. The coupling correction is obtained by minimizing the cross-talk central trajectory matrix response. | ||
| TUPPC004 | Study of a Lattice with a Lower Emittance at SOLEIL | 1155 |
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| The paper introduces the first preliminary feasibility study made at SOLEIL towards a possible future upgrade of the lattice in furthermore reducing the horizontal emittance, so to raise the storage ring performance. The approach taken is to employ whatever emittance reduction methods available, by respecting the given constraints on the lattice structure and the optics, particularly the circumference, insertion device straights, the required optics behavior as well as its tunability. Specifically, the possibility of introducing superbends into the double bend lattice is pursued, which are beneficial to hard X-ray users and could simultaneously help reducing the emittance thanks to its longitudinally varying field profile. Although the present study shall mainly focus on the linear properties of the optical solutions found, optimization of nonlinear optics is also discussed in view of the large dependence of the latter on the former. | ||
| TUPPC005 | Optimization of the SIS100 Nonlinear Magnet Scheme for Slow Extraction | 1158 |
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| The SIS100 superconducting synchrotron was initially planned mainly for fast extraction of protons and heavy ions. Due to the delay of the construction of the SIS300 synchrotron, SIS100 has to be able to provide slowly extracted heavy ion beams to the experiments. To improve the robustness of the slow extraction from SIS100, a lattice review was performed, resulting in an optimization of the nonlinear magnet scheme. In the original scheme the Hardt condition cannot be established due to a collapse of the dynamic aperture caused by the chromatic sextupoles. In the optimized scheme the positions of the chromatic sextupoles are modified and octupoles are employed to compensate the second order effects of these sextupoles. In addition, the number of resonance sextupole magnets is reduced. With the new scheme, the Hardt condition can be established, leading to higher extraction efficiency. The separatrix can be freely adjusted, and closed orbit control is improved. | ||
| TUPPC006 | CW Energy Upgrade of the Superconducting Electron Accelerator S-DALINAC | 1161 |
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Funding: This work is supported by the DFG through SFB 634. The S-DALINAC is a superconducting recirculating electron accelerator with maximum design energy of 130 MeV operating in cw at 3 GHz. Even so the gradients of the superconducting cavities are well above design, their design quality factor of 3*109 have not been reached so far. Due to the limited cooling power of the cryo-plant being 120 W, the final energy achievable in cw operation is around 85 MeV, currently. In order to provide a cw beam with the designed final energy in the future, the installation of an additional recirculation path is projected and to be finished by 2013. We review the design constraints related to the existing beam lines, report in detail on the magnet design (being the key issue) and the lattice calculations for the additional recirculation path. |
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| TUPPC007 | Electron Cloud Dynamics in a Gabor Space Charge Lens | 1164 |
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| Inside Gabor space charge lenses, external fields confine electrons forming a homogeneously distributed electron cloud. Its linear electric space charge field enables the focusing of high intensity heavy ion beams without aberrations. The focusing performance depends on the properties of the non-neutral plasma. In a small-scale table top experiment, different types of space charge lenses are used to characterize the collective behavior of the confined electron cloud using new non-interceptive diagnostic methods. The plasma parameters, e.g. electron temperature and density, are important to an improved understanding of loss and production mechanisms as well as the electron cloud dynamics. In this context, the evolution of instabilities caused by the enclosing fields has been investigated in detail. Experimental results will be presented and compared to numerical simulations. | ||
| TUPPC008 | Twiss Parameters of Coupled Particle Beams with Equal Eigenemittances | 1167 |
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| The parametrization of coupled beam motion has been studied intensively over the past decades. Nevertheless, there is still no representation of general coupled motion that would be as elegant and as complete as the one dimensional Courant-Snyder theory. In this context the consideration of different partial cases plays an important highlighting role, and in this paper we study the parametrization of coupled particle beams with equal eigenemittances. We show that such beams allow description which in many aspects resembles the one dimensional Courant-Snyder theory. | ||
| TUPPC009 | Dihedral Group and Repetitive Achromats with Mirror Symmetric or Mirror Antisymmetric Basic Cell | 1170 |
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Using the group-theoretical point of view for the design of magnetic optical achromats as introduced in*, we study in this paper second- and third-order repetitive achromats with a mirror symmetric or mirror antisymmetric basic cell. We also compare these achromats with repetitive achromats designed without internal cell symmetries taken into account.
* V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Two Cell Repetitive Achromats and Four Cell Mirror Symmetric Achromats, Proceedings of IPAC'10, Kyoto, Japan. |
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| TUPPC010 | Study of Effects of Failure of Beamline Elements and its Compensation in CW Superconducting Linac | 1173 |
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| Project-X is the proposed high intensity proton facility to be built at Fermilab in United States. First stage of the Project-X consists of H- superconducting linac (SC) which will be operated in continuous wave (CW) mode to accelerate the beam from kinetic energy of 2.1 MeV to 3 GeV. The operation in CW mode puts stringent tolerances on the beam line components, particularly at low energy section. The failure of beam line elements result in mismatch of the beam with the following sections due to different beam parameters than designed parameters. It makes the beam unstable which causes emittance dilution, and ultimately results in beam losses. In worst case, it can affect the reliability of the machine and may lead to the shutdown of the linac to replace the failed elements. Thus, it is important to study impacts of these effects and their compensation to restore linac performance to avoid beam interruption. This paper presents the studies performed for the failure of accelerating cavity and focusing magnets at the critical locations in the Project-X CW superconducting linac | ||
| TUPPC011 | Beam Steering Correction in FRIB Quarter-wave Resonators | 1176 |
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Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 The Quarter-Wave Resonators (QWR) section of the FRIB superconducting driver linac is required to accelerate Uranium beam up to 16 MeV/u in two different charge states simultaneously. This puts severe requirements on resonators alignment and field quality, in order to avoid beam losses and emittance growth. In particular, QWR beam steering can cause transverse oscillations of the beam centroid which reduce the linac acceptance and induces emittance growth. We have studied, with an analytical model and with 3D beam dynamics simulations, correction methods for the FRIB QWRs steering. We found that cavity shifting can provide effective steering cancellation in FRIB QWRs without need of cavity shape modifications, and allows to eliminate transverse beam oscillations and to improve beam quality. Calculation and simulation methods and results will be presented and discussed. Michigan State University designs and establishes FRIB as a DOE Office of Science National User Facility in support of the mission of the Office of Nuclear Physics. |
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| TUPPC012 | Optics of Extraction Lines at CNAO | 1179 |
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| The CNAO (National Center for Oncological Hadrontherapy), is the first Italian center for deep hadrontherapy with proton and carbon ion beams, treating patients since fall 2011. The beam is delivered to the patient through a high energy transfer line (HEBT). The line is equipped with a horizontal switching dipole that carries the beam in three treatment rooms and a vertical switching dipole that allows a vertical delivery of the beam in the central treatment room. The CNAO HEBT commissioning has been carried out using proton and Carbon beams in the full range of energies: 60 to 250 MeV/u for protons, 120 to 400 MeV/u for Carbon ions. Optimization of the beam lines setup has been carried out for few energies, applying beam magnetic rigidity scaling for the full range in steps of the order of 1 MeV. The scaling has proven to be satisfactory for most elements, and only minor adjustments in the initial part of the line were needed to fulfill tolerances in all the range. Repeatability of magnetic settings is supported by measurements along the lines. Finally the results in terms of beam dimensions, beam transmission and beam position at the patient position are presented. | ||
| TUPPC013 | Optimization of Lower Emittance Optics for the SPring-8 Storage Ring | 1182 |
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A design work of the present SPring-8 storage ring is in progress to improve its performance. The linear optics has been changed to reduce the natural emittance below the nominal of 3.4 nmrad at 8 GeV, and the nonlinear optics has been optimized with a genetic algorithm to suppress the amplitude-dependent tune shifts and to enlarge the dynamic aperture. As a preliminary study, the optics with the natural emittance of 2.4 nmrad at 8 GeV has been examined, theoretically and experimentally. In this optics, 1.5 times higher brilliance for 10 keV photons than the present can theoretically be expected for the standard undulator beamline. The improved optics design and its beam performance will be presented in detail. In this presentation, a optics for a future upgrade of the SPring-8 (SPring-8 II) will not be discussed, which is a full-scale major lattice modification, while the method we used in optimizing the nonlinear optics can also be adopted to the SPring-8 II*.
* Y. Shimosaki et al., "Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II," these proceedings. |
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| TUPPC014 | Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II | 1185 |
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A feasibility of a very low-emittance storage ring has been studied for an upgrade project, SPring-8 II. Its ultimate goal is to provide a superior brilliance for 0.5 ~ 100 keV photons. A sextupole bend lattice with the natural emittance of 70 pmrad at 6 GeV has been examined as the first candidate*. The nonlinear optics has been optimized to enlarge the dynamic aperture by correcting nonlinear resonances based on an isolated resonance Hamiltonian with thick lens approximation, and by non-interleaved sextupole method. A genetic algorithm, which has been examined to improve the performance of the present SPring-8**, will be adopted for detailed optimization of the tunes and sextupole strength to adjust the non-interleaved scheme and to correct higher order resonances. The correction scheme of nonlinear optics and its results will be presented in detail.
*Y. Shimosaki et al., IPAC’11, TUOAB01, p. 942 (2011). **Y. Shimosaki et al., "Optimization of Lower Emittance Optics for the SPring-8 Storage Ring", these proceedings. |
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| TUPPC015 | Local Modification of Lattice of a Long Straight Section for Installing Small Gap In-vacuum Undulators at SPring-8 | 1188 |
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| In the SPring-8 storage ring there are four magnet-free long straight sections (LSS) of about 30m. Recently we locally modified one of these sections by installing two quadrupole-triplets and divided it into three sub-sections. The vertical beta at the middle of each sub-section was lowered to 2.5m so that small gap in-vacuum undulators with a short period (min. gap: 5.2mm, period: 19mm) can be installed to build a high performance beamline for inelastic X-ray scattering. After modifying the lattice, however, the symmetry of the ring is lowered and, in general, it becomes difficult to keep sufficient dynamic aperture (DA) and momentum acceptance (MA). We solved this problem by combining the betatron phase matching, local chromaticity correction in LSS and cancellation of non-linear kicks due to sextupoles used for this correction. We could then recover DA and MA to almost the same level for the original one. The beam commissioning of the new lattice has successfully been finished, and from September 2011 it is used in user-operation. We will report our method of realizing a storage ring lattice having a very low symmetry and review the operation performance of the modified lattice. | ||
| TUPPC016 | Progress of Emittance Coupling Correction at the SPring-8 Storage Ring | 1191 |
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| The vertical beam spread, or the emittance coupling, is one of the most important parameters for the high brilliance light source storage ring. By the precise alignment of the magnets and the proper COD correction, at the commissioning phase of the SPring-8 storage ring we succeeded in achieving the very small coupling ~0.2 % without correction. However, the coupling had grown large with the years, so recently we have corrected it and recovered the initial performance. The scheme of the coupling correction at the SPring-8 storage ring is the global one, which is based on the perturbation theory with single resonance approximation. In the beginning of the correction the coupling was corrected by means of minimizing the vertical beam size. Then the performance of the coupling correction has been further improved by changing the scheme to minimizing the betatron coupling mode in the vertical oscillation of the horizontally kicked beam. This result implies that the higher order coupling contributes to the emittance coupling, which can be corrected by the higher skew multi-pole magnet. The present status of the coupling correction at the SPring-8 storage ring will be reported. | ||
| TUPPC017 | Orbit and Optics Correction to Realize Designed Machine Performance | 1194 |
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| It is difficult for actual accelerators to achieve the designed machine performance without appropriate correction or adjustment of magnet errors. By correction as magnets are aligned to design orbit, we aim to be realized the designed machine performance. However, it is not easy to estimate the design orbit in real accelerators. In KEKB and PF, beam position monitor(BPM) can be calibrated to the center of quadrupole magnet(QM). BPM and QM misalignments (except rotation misalignment) referring to design orbit can be estimated using assumption that these misalignments are coincident. This is, design orbit at BPM and QM can be derived. | ||
| TUPPC018 | Estimation of Orbit and Optics Distortion of SuperKEKB by Tunnel Deformation | 1197 |
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| The tunnel which was used for the KEKB B-factory is reused for the accelerator tunnel of the SuperKEKB. The total vertical displacement of the tunnel subsidence reached almost 30mm during 10 years KEKB operation. In order to operate the SuperKEKB which might be more delicate machine than the previous KEKB B-factory, we are evaluating the optics distortion by the tunnel deformation and studying the machine performance after the orbit and optics correction. We report the estimation of the machine performance degradation by the tunnel subsidence and the requirement of the correction. | ||
| TUPPC019 | Beam Dynamics Simulations of J-PARC Main Ring for Damage Recovery from the Tohoku Earthquake in Japan and Upgrade Plan of Fast Extraction Operation | 1200 |
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| Magnets of Japan Proton Accelerator Research Complex (J-PARC) were shaken by the Tohoku Earthquake in Japan on March 11th, 2011. The alignment of J-PARC Main Ring (MR) received 20 mm displacement horizontally and 6 mm vertically. Beam dynamics simulations were performed to estimate the effect of the displacement on closed orbit distortions and beam loss in fast extraction (FX) operation of J-PARC MR. Based on the simulation results, we concluded that re-alignment of J-PARC MR was needed to achieve high-power beam. The re-alignment of MR was finished on October 28th, 2011. We also considered the effects of the earthquake on the upstream of MR to establish our upgrade plan, which was based on beam dynamics simulations optimizing collimator balance of injection beam transport (3-50BT) and MR, and RF patterns. J-PARC MR FX operation was resumed from December 2011. | ||
| TUPPC020 | A Scheme for Horizontal-vertical Coupling Correction at SuperKEKB | 1203 |
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| SuperKEKB is an 7 GeV electron and 4 GeV positron double ring collider project based on the nano beam scheme and is aimed to break the world's luminosity record. A horizontal flat beam is essential to realize the nano beam collisions. One of critical effect that induces unexpected coupling is machine error, such as magnet misalignment and field imperfection. Coupling correction, therefore, plays key role in the actual beam operation. In this study, we numerically explore a possible scheme for coupling correction in the SuperKEKB lattice. Some coupling measurement and correction methods are applied to the model lattice considering magnet misalignments and finite BPM resolution. Based on the results, the attainable smallest coupling in the actual SuperKEKB is discussed. | ||
| TUPPC021 | Design Study on KEK Injector Linac Upgrade for High-current and Low-emittance Beams | 1206 |
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| Injector linac at KEK is now under upgrading to produce high current (5nC for e-, 4nC for e+) and low emittance (20 mm mrad for e-, 6 mm mrad for e+) electron and positron beams to a SuperB collider called SuperKEKB. Emittance growth resulted from both wakefield at the acceleration structure and dispersive effects at the focusing structure are troublesome in keeping the beam quality during the beam propagation. In this study, a possible solution to mitigate these effects in the KEK injector linac is explored by considering bunch compression in an existing bending section, orbit correction to suppress the wakefield excitation, and beam optics design. | ||
| TUPPC022 | Straight Scaling FFAG Experiment | 1209 |
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| Straight scaling FFAG experiment has been done at Kyoto University research reactor institute. Details and results are presented here. | ||
| TUPPC023 | Waist Corrections at the Interaction Point of ATF2 in the Presence of IPBSM Fringe Rotations and Input Beam Sigma13, Sigma24 | 1212 |
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| The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam (or equivalently a σ13 correlation), as well as a σ24 correlation, can break the orthogonality in the main σ34 and σ32 waist corrections during the minimization and result in larger vertical beam sizes at IP. Both effects are studied, analytically and in simulation, and a practical procedure is suggested for diagnosing the presence of a residual fringe tilt, by measuring the influence of the horizontal waist correction on the minimum vertical beam size. | ||
| TUPPC024 | R&D of an Ultrafast Probe Apparatus Based on MeV Electron Diffraction at Tsinghua University | 1215 |
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Funding: This work is supported by National Natural Science Foundation of China and National Basic Research Program of China (973 Program). An ultrafast probe apparatus based on MeV ultrafast electron diffraction is developed at Tsinghua University. It aims at generating 1.5 to 3 MeV pulse with sub-pC charge and sub-ps pulse length for pump-probe experiments. It consists of an S-band 1.6-cell radiofrequency photocathode gun, a solenoid, a sample chamber, a deflecting cavity, a detection system and other diagnostics tools. Simulations show the position of solenoid coil affects the spot size on detection screen and the charge of collimated bunch significantly. The collimator is found to be helpful to stabilize the charge of collimated bunch and reduce its normalized emittance. The construction of the apparatus is almost finished and the commissioning test will start soon. |
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| TUPPC025 | Solaris Storage Ring Lattice Optimization with Strong Insertion Devices | 1218 |
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Funding: Work supported by the European Regional Development Fund within the frame of the Innovative Economy Operational Program: POIG.02.01.00-12-213/09 The Solaris synchrotron light facility under construction in Kraków will be a replica of the 1.5 GeV storage ring of MAX IV. This compact 3rd generation light source has been designed to have an emittance of 6 nmrad and operate with 500 mA stored current for VUV and soft X-Rays production. The lattice design consists of 12 Double Bend Achromats (DBA) with each DBA cell integrated into one solid iron block. Twelve 3.5 m long straight sections are available of which 10 will be equipped in various insertion devices. These devices will differ from those adopted by MAX IV. For X-ray production one or more superconducting wigglers will be used, while APPLE II type undulators will be used for variable polarised light production. The linear and nonlinear lattice dynamics have been studied with these perturbing insertion devices included in the ring and results are presented in this paper. |
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| TUPPC026 | Design of Compact C-Band Standing-Wave Accelerating Structure Enhancing RF Phase Focusing | 1221 |
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Funding: Work supported by POSTECH Physics BK21 Program. We design a C-band standing-wave accelerating structure for an X-ray source of the imaging and medical applications. It is capable of producing 6-MeV, 100-mA pulsed electron beams which is focused by less than 1.5 mm without external magnets. As an RF source, we use peak 1.5-MW magnetron with duty factor of 0.08%. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists 3 bunching cells, 13 normal cells and a coupler cell. It operated with π/2-mode standing-waves. The bunching section is designed to enhance the RF phase focusing in order to achieve 1.2-mm beam spot size. Each cavity is designed with the MWS code to maximize the effective shunt impedance within 3.5% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics simulation by the PARMELA code. |
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| TUPPC027 | Multi Objective Genetic Optimization for Linac Lattice of PAL XFEL | 1224 |
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Funding: Work supported by MEST and POSTECH Physics BK21 Program. There are a large number of variables and objectives in design of XFEL linac lattices. Recently, most of accelerator physics field, are applying the multi-objective genetic algorithm (MOGA) for these kinds of problems. MOGA was applied to the PAL XFEL linac lattice design. Longitudinal position of all components was fixed before applying MOGA. RF parameters of RF cavities and bending angles of bunch compressors are selected as variables. Various beam parameters computed by ELEGANT were used as objectives. By using MOGA, new linac lattice designs with 2 and 3 bunch compressors was generated and their beam properties are presented in this paper. |
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| TUPPC030 | Status of the Ion Sources at ESS-Bilbao | 1227 |
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| Currently there are two types of ion sources under development and testing at ESS-Bilbao, the first one is a Penning type source based on the ISIS/RAL source, modified to use permanent magnets to generate the Penning field. The second source is an off-resonance ECR source that is being developed in-house. The Penning source is in the late stages of commissioning, and a beam has been extracted from it. Currently the main work on that source is in the optimization of the operating parameters. The ECR source on the other hand is in the early stages of the commissioning, all parts have been fabricated, and Vacuum tests are underway. Testing of the RF and control systems will follow, and finally the whole system will be tested. The control system for both ion sources was developed under LabView, and runs on a real time system. While for testing the timing sequences run locally, the system is being developed so that it can run using a central timing system. | ||
| TUPPC033 | Random Walk Optimization in Accelerators: Vertical Emittance Tuning at SLS | 1230 |
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| The operation of a high performance accelerator is realized only when several beam based corrections are implemented. These corrections are, however, limited by measurement errors as the correction approaches the ideal value. To overcome this limitation, we investigate the application of a random walk (RW) optimization specifically to minimize the vertical emittance at the SLS. A systematic minimization is performed by measuring linear coupling and spurious vertical dispersion and correcting them using 36 skew quadrupole correctors. On the other hand, the minimization can be performed by simply applying a multi-variable optimization from the mathematics point of view, where the best combination of skew corrections is to be found. The measured vertical beam size is available as a stable target function of the minimization even at very low vertical emittance. Although RW and other algorithms are implemented into various accelerator computer codes, it is interesting to apply this concept to the real machine, where measurement errors are unavoidable and may prohibit systematic minimization based on a machine model. Possible applications of the technique in general are also discussed. | ||
| TUPPC034 | Preparation of SLS for IBS Measurements | 1233 |
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| It is planned to use the SLS for testing damping ring issues related to linear colliders. One aspect is the study of Intra-Beam Scattering (IBS) effects, which are a limiting factor for ultra-low emittance rings. In this paper we present the setup and characterization of a new mode of operation in which the SLS runs at lower energy (1.57 GeV) with a natural emittance of 2.4 nm rad. This is much smaller than that at the nominal energy (2.41 GeV) and should make IBS effects more easily visible. In order to be able to observe IBS a careful setup is required: Optics measurement and correction as well as measurements of the bunch natural energy spread and the onset of turbulent bunch lengthening. Also, a detailed discussion on the available diagnostics and their limitations are shown and finally some preliminary results of beam emittance measurements, in all three planes, as a function of single bunch current are presented. | ||
| TUPPC035 | Design of a Surface Muon Beam Line for High Field muSR at the PSI Proton Accelerator Facility | 1236 |
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| Starting from 2012, a high field muSR (muon spin rotation/relaxation/resonance) facility will come into operation in the piE3 secondary beam line located at the target station E of the PSI proton accelerator. For this purpose, the last part of the beam line has been redesigned in order to integrate two electrostatic spin rotator devices providing a 90° rotation of the muon spin. At the same time, requirements of small beam diameter (σ ≈ 10 mm) as well as small momentum bite (δp/p ≈ 1%) in the sample region have to be met. This work focuses on the simulation of the beam optics (28 MeV/c design momentum). Particular concern is given to potential transmission losses caused by the spin rotator devices. The matching of the beam line with the high magnetic field up to 9.5 T surrounding the sample region has been considered as well. An overview of the spin rotator devices, specifically designed for this project, is also presented. | ||
| TUPPC036 | Integration with the LHC of Electron Interaction Region Optics for a Ring-ring LHeC | 1239 |
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| The Large Hadron Electron Collider (LHeC) project is a proposal to study e-p and e-A interactions at the LHC. One design uses an electron synchrotron to collide a 60GeV e± beam with the 7TeV proton beam. Designing a new accelerator around the existing LHC machine poses unique challenges, particularly in the interaction region (IR). The electron beam must be quickly separated from the proton beam after the interaction point (IP) to avoid beam-beam effects, while not significantly reducing luminosity or producing large amounts of synchrotron radiation. The proton beam must pass through the electron optics, while the electron beam must avoid the proton optics. The long straight section requires bending in both planes to counteract the IP crossing angle and to displace the beam vertically from the electron machine to the proton IP. An achromatic bending scheme is used in the vertical plane to eliminate dispersion at the IP and provide an optics which is well matched to the LHeC ring lattice. The interaction region and long straight section design is presented and detailed, and the design process and principles discussed. | ||
| TUPPC037 | Update on LHeC Ring-Ring Optics | 1242 |
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| An update of the LHeC Ring-Ring optics is presented which accounts for chromatic corrections and more flexibility in the tune adjustment. | ||
| TUPPC038 | Interaction Region Optics for the Non-Interacting LHC Proton Beam at the LHeC | 1245 |
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| The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. Two electron accelerator designs are being studied; a linac and a synchrotron. In the synchrotron option, a 60GeV electron beam is collided with one of the LHC proton beams to provide high luminosity TeV-scale interactions. The interaction region for this scheme is complex and introduces a series of challenges due to the integration of the two machines. One of these is the optics of the second non-interacting proton beam. The second proton beam must not interfere with the LHeC experiment, but simultaneous running of the remaining LHC experiments requires that this beam must still circulate relatively undisturbed. This paper discusses methods to solve these challenges for the electron synchrotron design. | ||
| TUPPC039 | Synchrotron Radiation Studies for a Ring-Ring LHeC Interaction Region and Long Straight Section | 1248 |
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| The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. In the design for an electron synchrotron (alternative designs for a linac are also under development), a 60GeV e± beam is collided with a 7TeV LHC proton beam to produce TeV-scale collisions. Despite being much lower energy than the proton beam, the electron beam is high enough energy to produce significant amounts of synchrotron radiation (SR). This places strong constraints on beam optics and bending. In particular challenges arise with the complex geometry required by the long straight section (LSS) and interaction region (IR). This includes the coupled nature of the proton and electron optics, as SR produced by the electron beam must not be allowed to quench the superconducting proton magnets or create problems with beam-gas backgrounds. Despite this, the electron beam must be deflected significantly within the IR to produce sufficient separation from the proton beam. | ||
| TUPPC040 | Model Calibration and Optics Correction Using Orbit Response Matrix in the Fermilab Booster | 1251 |
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| A beam-based method of optical model calibration using the measured orbit response matrix, known as the LOCO method, was successfully applied to Fermilab's rapid-cycling Booster synchrotron. Orbit responses were measured by individually changing the strength of each dipole corrector throughout the acceleration cycle, and dispersion was measured by changing the beam's radial offset. The model calibration procedure revealed large calibration errors for all elements in the Booster's recently-installed multipole corrector packages and beam position monitors. The resulting model was used to correct coupling and beta beating. | ||
| TUPPC041 | A 3 TeV Muon Collider Lattice Design | 1254 |
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Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy A new lattice for 3 TeV c.o.m. energy with β*=5mm was developed which follows the basic concept of the earlier 1.5 TeV design* but uses quad triplets for the final focus in order to keep the maximum magnet strength and aperture about the same as in 1.5 TeV case. Another difference is employment of combined-function magnets with the goal to lower heat deposition in magnet cold mass and to eliminate regions without bending field which produce “hot spots” of neutrino radiation that can be an issue at higher energy. The proposed lattice is shown to satisfy the requirements on luminosity, dynamic aperture and momentum acceptance. * Y.Alexahin, E.Gianfelice-Wendt, A.Netepenko, Proc. IPAC10, Kyoto, May 2010, p. 1563 |
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| TUPPC042 | Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics | 1257 |
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Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy In order to achieve peak luminosity of a Muon Collider (MC) in the 1035/cm2/s range very small values of beta-function at the interaction point (IP) are necessary (β* ~ 5 mm) while the distance from IP to the first quadrupole can not be made shorter than ~6m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the case of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors. |
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| TUPPC043 | Design of Accumulator and Compressor Rings for the Project-X Based Proton Driver | 1260 |
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Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. A Muon Collider (MC) and Neutrino Factory (NF), which may be considered as a step towards MC, both require high-power (~4 MW) proton driver providing short (<1m) bunches for muon production. However, the driver repetition rate required for these two machines is different: ~15 Hz for MC and ~60 Hz for NF. This difference necessitates employing two separate rings: one for accumulation of the proton beam from the Project-X linac in a few (e.g., 4) long bunches, the other for bunch compression - one by one for NF or all at a time for MC with simultaneous delivery to the target. The lattice requirements for these two rings are different: the momentum compaction factor in the accumulator ring should be large (and possibly negative) to avoid the microwave instability, while the compressor ring can be nearly isochronous in order to limit the required RF voltage and reduce the dispersion contribution to the beam size. In the present report we consider ring lattice designs which achieve these goals. |
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| TUPPC044 | Emittance and Phase Space Tomography for the Fermilab Linac | 1263 |
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Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy. The Fermilab Linac delivers a variable intensity, 400-MeV beam to the The MuCool Test Area experimental hall via a beam line specifically designed to facilitate measurements of the Linac beam emittance and properties. A 10 m, dispersion-free and magnet-free straight utilizes an upstream quadrupole focusing triplet in combination with the necessary in-straight beam diagnostics to fully characterize the transverse beam properties. Since the Linac does not produce a strictly elliptical phase space, tomography must be performed on the profile data to retrieve the actual particle distribution in phase space. This is achieved by rotating the phase space distribution using different waist focusing conditions of the upstream triplet and performing a de-convolution of the profile data. Preliminary measurements using this diagnostic section are reported here. |
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| TUPPC045 | Modeling Investigation on a Deflecting-Accelerating Composite RF-cavity System for Phase Space Beam Control | 1266 |
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Phase space manipulations between the longitudinal and transverse degree of freedoms hold great promise toward the precise control of electron beams. Such transverse-to-longitudinal phase space exchange have been shown to be capable of exchanging the transverse and horizontal emittance or controlling the charge distribution of an electron bunch, for beam-driven advanced accelerator methods. The main limitation impinging on the performance of this exchange mechanism stems from the external coupling nature of a realistic deflecting cavity, compared to a thin-lens model. As an extended idea from *, this paper presents the design of a composite 3.9-GHz RF-system consisting of a deflecting- and accelerating-mode cavities. The system design analysis is discussed with particle-in-cell (PIC) simulations of the device performance.
* A. Zholents, PAC'11. |
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| TUPPC046 | Further Analysis of Real Beam Line Optics from a Synthetic Beam | 1269 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a license to publish or reproduce this manuscript for U.S. Government purposes. Standard closed-orbit techniques for Twiss parameter measurement are not applicable to the open-ended Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. The evolution of selected sets of real orbits in the accelerator models the behavior of a “synthetic” beam. This process will be validated against beam profile-based Twiss parameter measurements and should provide the distributed optical information needed to optimize beamline tuning for an open-ended system. This work will discuss the current and future states of this technique, as well as an example of its use in the CEBAF machine. |
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| TUPPC047 | New Storage Ring Lattice for the Duke FEL Wiggler Switchyard System | 1272 |
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Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. The Duke storage ring is a dedicated drive for the OK-4 FEL and OK-5 FEL, and for the state-of-the-art Compton gamma-ray source, High Intensity Gamma-Ray Source (HIGS). To produce FEL lasing below 190 nm and gamma-ray beams above 100 MeV, the FEL system needs to be upgraded by adding two helical OK-5 wigglers to increase the FEL gain with four OK5 wigglers for the VUV operation. To simultaneously preserve the linear polarization capability of the gamma-ray beam produced by the planar OK-4 FEL, a wiggler switchyard system is under development which will enable the switch between two planar OK-4 wigglers and two helical OK-5 wigglers in the middle of the FEL straight. In this work, we present the new magnetic lattice designed for the operation of the wiggler switchyard system. This new lattice is developed with great flexibility for the operation with different numbers of FEL wigglers, variable betatron tunes, and adjustable electron beam sizes at the collision point for the HIGS. In addition, the new lattice is developed for the operation in a wide range of energies, from 280 MeV to 1.2 GeV, with proper nonlinear dynamics compensations in order to realize a large dynamic aperture. |
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| TUPPC048 | Online Physics Model Platform | 1275 |
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Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 For a complex accelerator such as the Facility for Rare Isotope Beams (FRIB), a transfer matrix based online model might not be sufficient for the entire machine. On the other hand, if introducing another modelling tools, physics applications have to be rewritten for all modelling tools. A platform which can host multiple modelling tools would be ideal for such scenario. Furthermore, the model platform along with infrastructure support can be used not only for online applications but also for offline purposes with multi-particle tracking simulation. In order to achieve such a platform, a set of common physics data structures has to be set. XAL's accelerator hierarchy based data structure is a good choice as the common structure for various models. Application Programming Interface (API) for physics applications should also be defined within a model data provider. A preliminary platform design and prototype is discussed. |
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| TUPPC049 | A Tapered-foil Emittance-exchange Experiment at LANSCE | 1278 |
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We are planning an experiment at the Los Alamos Neutron Science Center (LANSCE) to demonstrate a technique for reducing the transverse emittance of the proton beam by passing the beam through a wedge-shaped energy degrader to produce a non-symplectic correlation between transverse position and energy, then removing this correlation with a bending magnet. This technique was proposed by Peterson* in 1983. We present a specific beamline layout that is expected to mitigate several complications associated with fielding an experiment to demonstrate the technique with a low-emittance proton beam. We present simulated results and expected outcomes of this demonstration.
* J. M. Peterson, Proc. of PAC 1983, pP. 2403-2405 (1984). |
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| TUPPC050 | Beam Transport and Storage with Cold Neutral Atoms and Molecules | 1281 |
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Funding: US Department of Energy Paramagnetic neutral atoms and molecules are subject to magnetic-field-gradient forces on their magnetic moments. Li atoms and CaH molecules both have an effective magnetic moment of about one Bohr magneton, and in the presence of a strong (~1 T) magnetic field, acquire a Zeeman energy of one of two values, ±μ|B|. Particles with positive (negative) energy are repelled by (attracted toward) increasing fields. Li and CaH can be laser-cooled to speeds of tens of m/s and the corresponding magnetic fields needed for transport and injection are on the order of 1 T. The stable stored state is the field-repelled state. Many concepts of accelerator physics apply to our neutral particles. The analog of charge-exchange injection into storage rings is laser-based optical pumping from a field-seeking state to a field-repelled state. The role of dipoles in charged-particle optics is played by quadrupoles in neutral particle optics, and the role of quadrupoles by sextupoles. We present our design and tracking results for a neutral atom/molecule accumulator including an injection chicane with a laser-stimulated state-flip. |
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| TUPPC051 | FACET Tolerances for Static and Dynamic Misalignment | 1284 |
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Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. The Facility for Advanced Accelerator and Experimental Tests (FACET) at the SLAC National Accelerator Laboratory is designed to deliver a beam with a transverse spot size on the order of 10 μm x 10 μm in a new beamline constructed at the two kilometer point of the SLAC linac. Commissioning the beamline requires mitigating alignment errors and their effects, which can be significant and result in spot sizes orders of magnitude larger. Sextupole and quadrupole alignment errors in particular can introduce errors in focusing, steering, and dispersion which can result in spot size growth, beta mismatch, and waist movement. Alignment errors due to static misalignments, mechanical jitter, energy jitter, and other physical processes can be analyzed to determine the level of accuracy and precision that the beamline requires. It is important to recognize these effects and their tolerances in order to deliver a beam as designed. |
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| TUPPC052 | Longitudinal Beam Tuning at FACET | 1287 |
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| Commissioning of the Facility for Advanced acCelerator Experimental Tests (FACET) at SLAC began in July 2011. In order to achieve the high charge density required for users such as the plasma wakefield acceleration experiment, the electron bunch must be compressed longitudinally from ~6 mm down to 20 microns. This compression scheme is carried out in three stages and requires careful tuning, as the final achievable bunch length is highly sensitive to errors in each consecutive stage. In this paper, we give an overview of the longitudinal dynamics at FACET, including beam measurements taken during commissioning, tuning techniques developed to minimize the bunch length, optimization of the new “W” chicane at the end of the linac, and comparison with particle tracking simulations. In addition, we present additional diagnostics and improved tuning techniques, and their expected effect on performance for the upcoming 2012 user run. | ||
| TUPPC053 | Longitudinal Tuning of the SNS Superconducting Linac | 1290 |
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Funding: This work was supported by SNS through UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy. The SNS superconducting linac delivers proton beam with about 1 GeV of energy driven by self-consistent RF cavities. Here, we present an experience of the longitudinal tune-up of the SNS superconducting linac where a new application for quick RF phase setup and cavity fault adaptation was created. The routine of superconducting linac tune-up, longitudinal beam manipulation, and radio frequency cavity phase scaling for beam state recovery is presented. The application has direct value for beam optics study and will serve as the basis for longitudinal beam-size manipulation for a laser stripping project. |
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| TUPPC054 | Beam Acceleration by a Multicell RF Cavity Structure Proposed for Improved Yield in Hydroforming | 1293 |
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Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. We study the accelerating properties of a new multicell cavity structure with irises forming a rectangular aperture between the cavity cells. We are interested in this structure because, from a mechanical point of view, the rectangular iris may make possible a much improved structure quality using a hydroforming manufacturing process. RF analysis shows that the rectangular iris shape provides asymmetric transverse focusing per half RF period. If the horizontal and vertical rectangular irises are interleaved, the net transverse focusing can be increased. The present studies of the acceleration and transport properties of these cavities are conducted by tracking particles through time-dependent 3D cavity fields from CST MWS using the ORBIT Code. |
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| TUPPC055 | Development of an Automatic MATLAB based Emittance Measurement Tool for the IAC Accelerators | 1296 |
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| At the Idaho Accelerator Center (IAC) of Idaho State University, we have been operating fifteen low energy accelerators. To optimize those accelerators properly, we have to measure the transverse beam emittance. To measure the transverse beam emittance of an S-band linear accelerator with the quadrupole scan technique, we installed an Optical Transition Radiation (OTR) screen and a digital CCD camera in the bealime of the accelerator. From the images of the digital CCD camera, the transverse beam profile on the OTR screen can be acquired. To extract the transverse beam size and to estimate the transverse emittance, we have developed a MATLAB program. This paper describe the details of the MATLAB program and performance of our MATLAB based emittance measurement tool. | ||
| TUPPC056 | Optics Measurements and Corrections at RHIC | 1299 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The further improvement of RHIC luminosity performance requires more precise understanding of the RHIC modeling. Hence, it is necessary to minimize the beta-beat, deviation of measured beta function from the calculated beta functions based on an model. The correction of beta-beat also opens up the possibility of exploring operating RHIC polarized protons at a working point near integer, a preferred choice for both luminosity as well as beam polarization. The segment-by-segment technique for reducing beta-beat demonstrated in the LHC operation for reducing the beta-beat was first tested in RHIC during its polarized proton operation in 2011. It was then fully implemented during the RHIC polarized proton operation in 2012. This paper reports the commissioning results. Future plan is also presented. |
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| TUPPC057 | RHIC Spin Flipper Commissioning Results | 1302 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The five ac dipole design of RHIC spin flipper in the Blue ring was first commissioned during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper*. Spin flipping efficiency was measured with both 100 GeV and 250 GeV polarized proton beams. This paper presents the latest commissioning results. * M. Bai , T. Roser, C. Dawson, Y. Makdisi, W. Meng, F. Meot, P. Oddo, C. Pai, P. Pile, RHIC Spin Flipper New Design and Commissioning Plan, IPAC10 proceedings, IPAC 2010, Kyoto, Japan, 2010 |
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| TUPPC058 | Beam Energy Variation with Dipole Fault | 1305 |
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Funding: Supported by Department of Energy Contract No. DE-AC02-98CH10886. The effect of dipole faults and closed orbit correction on the beam energy is studied both analytically and numerically using the ELEGANT code. Motivated by top-off safety analysis, we consider the case of single dipole faults and study how large an error can be compensated by the closed orbit correction system before the beam is lost. |
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| TUPPC059 | Extraction of the Lie Map from Realistic 3D Magnetic Field Map | 1308 |
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Funding: Supported by Department of Energy Contract No. DE-AC02-98CH10886. We present a method to extract the Lie map of any arbitrary accelerator magnet from its actual 3D field map. After fitting a Taylor map from multi-particle tracking trajectories through the actual field, we factorize the map into a Lie map using Dragt-Finn's method. This method is validated by comparing with COSY-infinity for a soft-edge quadrupole model. Applications of extracting symplectic maps for the SPEAR and NSLS-II dipoles are shown as examples. A comparison of the map-tracking results against the direct field-integration-based method also is given. |
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| TUPPC060 | Beam Optics and the pp2pp Setup of the STAR Experiment at RHIC | 1311 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The newly installed forward detector system at the STAR experiment at RHIC measures small angle elastic and inelastic scattering of polarized protons on polarized protons. The detector system makes use of a pair of Roman Pot (RP) detectors, instrumented with silicon detectors, and located on either side of the STAR intersection region downstream of the DX and D0 dipoles and quadrupole triplets. The parallel to point optics is designed so that scattering angles are determined from position measurements at the RP's with small error. The RP setup allows measurement of position and angle for a subset of the scattered protons. These measured position/angle correlations at the RP's can be compared with optics model predictions to get a measure of the accuracy of the quadrupole triplet current settings. The current in each quadrupole in the triplets is comprised of sums and differences of up to six power supplies and an overall 1% error in the triplet field strengths results in a 4% error in four-momentum transfer squared. This technique is also useful to check the polarity of the skew elements located in each quadrupole triplet. Results of the analysis will be presented. |
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| TUPPC061 | Commissioning of a beta∗ Knob for Dynamic IR Correction at RHIC | 1314 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In addition to the recent optics correction technique demonstrated at CERN and applied at RHIC, it is important to have a separate tool to control the value of the beta functions at the collision point (beta∗). This becomes even more relevant when trying to reach high level of integrated luminosity while dealing with emittance blow-up over the length of a store, or taking advantage of compensation processes like stochastic cooling. Algorithms have been developed to allow modifying independently the beta function in each plane for each beam without significant increase in beam losses. The following reviews the principle of such algorithms and their experimental implementation as a dynamic beta-squeeze procedure. |
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| TUPPC062 | Transfer of Polarized 3He Ions in the AtR Beam Transfer Line | 1317 |
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Funding: Work supported by the US Department of Energy In addition to collisions of electrons with various unpolarized ion species as well as polarized protons, the proposed electron-hadron collider (eRHIC) will also facilitate the collisions of electrons with polarized 3He ions. The AGS is the last acceleration stage of ions before injection into one RHIC for final acceleration. The AtR (AGS to RHIC) transfer line will be utilized to transport the polarized 3He ions from AGS into one of the RHIC’s collider rings. In this paper we investigate the extraction energy of the polarized 3He ions from the AGS which will optimize the polarization of 3He ions injected into RHIC. Some of the peculiarities (interleaved horizontal and vertical bends) of the AtR line's layout may degrade this spin matching of the polarized 3He ions. We will also discuss possible simple modifications of the AtR line to accomplish a perfect “spin matching” of the injected 3He beam with that of the stable spin direction at the injection point of the RHIC ring. |
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| TUPPC063 | The AGS Synchrotron with Four Helical Magnets | 1320 |
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Funding: *Work supported by the US Department of Energy. The idea* of using two partial helical magnets was applied successfully to the AGS synchrotron**, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides a larger “spin tune gap” for the placement of both the vertical and horizontal tunes of the AGS during acceleration, second. Although the same spin gap can be obtained with two partial helices of equal strength, the required strength of the two helices makes it impractical. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and comparison of these results with the present setup of the AGS that uses two partial helical magnets***. * T. Roser et al., Proc. EPAC04, p. 1577 (2004). ** H. Huang et al., PRL 99, 154801(2007). *** N. Tsoupas et. al., these proceedings. |
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| TUPPC065 | High Intensity Beam Analysis for the Superconducting Radio-frequency Linac (SRF-Linac) of the IFMIF-EVEDA Accelerators | 1323 |
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| In this proceeding we analyze space charge effects on the beam dynamics of IFMIF accelerators. The objective is to be able to characterize and understand the crucial issues like halo formation, emittance growth and sudden particle losses in the SRF-Linac. We use the Hofmann stability charts to identify modes of collective space charge density oscillations that are responsible for the transfer and growth of the emittance. With identification of modes we are able to treat the parametric resonance between the modes and the nonlinear motion of an individual ion the amplitude of which is greater than the core radius. The resulting phase space consists of an inner separatrix containing the core and an outer separatrix that becomes the locus near which the halo particles enter and cluster. | ||
| TUPPC067 | How to Achieve Longitudinally Polarized Electrons using Integer Spin Tune Resonances | 1326 |
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Funding: Bundesministerium für Bildung und Forschung Commonly, strong solenoids are used in circular accelerators to achieve longitudinal polarization. In practice, however, these solenoids cause a phase space coupling, which has to be compensated for by sophisticated decoupling schemes. We suggest to adiabatically ramp into an integer spin tune resonance, while preserving the degree of polarization. When appropriately adjusting the driving horizontal field contributions at the final energy, the resulting polarization is longitudinal at predefined positions in the accelerator. Here, depending on the energy spread, the degree of polarization is conserved for several seconds. The contribution shows the numerical analysis of this scenario being confirmed by first demonstration tests at the ELSA stretcher ring. |
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| TUPPC069 | Third-Order Apochromatic Drift-Quadrupole Beamline | 1329 |
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We have shown that for every drift-quadrupole system there exists an unique set of Twiss parameters (apochromatic Twiss parameters), which will be transported through that system without first order chromatic distortions*. In this paper we continue the development of the theory of apochromatic focusing and present the design of a straight drift-quadrupole system which can transport apochromatic beam ellipses without influence not only of the second but also of the third order chromatic and geometric aberrations of the beamline transfer map.
* V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Apochromatic Beam Transport in Drift-Quadrupole Systems. Proceedings of IPAC'10, Kyoto, Japan. |
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| TUPPC070 | Alternating Spin Aberration Electrostatic Lattice for EDM Ring | 1332 |
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| The idea of the electric dipole moment search using the storage ring (SrEDM) with polarized beam is realized under condition of the long-time spin coherency of all particles, the time during which the RMS spread of the spin orientation of all particles in the bunch reaches one radian. Following the requirements of the planned EDM experiment, the SCT should be more than 1000 seconds. During this time each particle performs about 109 turns in the storage ring moving on different trajectories through the optics elements. At such conditions the spin-rotation aberrations associated with various types of space and time dependent nonlinearities start to play a crucial role. In this paper we consider a new method based on the alternating spin drift, causing it to rotate alternately, thereby limiting the growth of aberrations at one order of magnitude lower. As a result, using this method we can achieve the SCT of the order of 5000-6000 seconds. The difficulties of these studies are still in the fact that the aberrations growth observed in the scale of a 109 turns. For the study we use an analytical method in composition with a numerical simulation by COSY Infinity. | ||
| TUPPC071 | Comparison of Different Numerical Modelling Methods for Beam Dynamics in Electrostatic Rings | 1335 |
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| To search the electric dipole moment was proposed to use polarized protons at the so-called "magic" momentum of 0.7 GeV/c in an electric storage ring. For studying beam dynamics in electrostatic rings different computational methods can be used. We used differential algebra methods realized in COSY Infinity and integrating program with symplectic Runge-Kutta methods. These methods were observed and compared for orbital and spin motion. | ||
| TUPPC072 | Modeling of Matching Channel for Accelerator Complexes | 1338 |
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| Practically modern accelerator facility can be considered as a composite machines. Therefore it is necessary to consider special matching channels to joint all accelerator components together. For such channels advance various requirements, which can be formulated in the form of criteria sets. In this paper considered a global optimization concept allows to find appropriate solutions sets. This approach is demonstrated on the problem of modeling the matching channels for NICA accelerator complex. | ||
| TUPPC073 | Frequency Map Analysis for SuperB | 1341 |
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| The frequency map analysis is applied to the SuperB HER and LER lattices including the Final Focus, in order to understand the dynamic aperture limitation and provide insight for a working point optimization. In this respect, frequency and diffusion maps are evaluated applying random magnet misalignments and tilts, before and after correction of orbit, dispersion and coupling using Low Emittance Tuning techniques. The same analysis is performed for on and off momentum particles. The lattice properties are further investigated using working point scans and the correction of non linear resonance driving terms and amplitude detuning. | ||
| TUPPC074 | Study of Resonance Driving Term in Electron Storage Rings | 1344 |
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| The resonance driving term (RDT) is useful to analyze and optimize the nonlinear performance of the storage ring. In addition to analytical calculation of RDT, experimental measurement of RDT has been made in some proton storage rings based on turn-by-turn BPM data. For electron storage rings, the analysis is more complicated due to decoherence effects and strong radiation damping. The relation between spectral decomposition of BPM data and RDT is derived and validated using beam numerical tracking data in this paper. | ||
| TUPPC075 | Study of Nonlinear Beam Dynamics Effects for DEPU at SSRF | 1347 |
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| A pair of EPUs (DEPU) with the period 58mm and 148mm, covering the energy ranges from 20 to 200eV and 200 to 2000eV of arbitrary polarized light, will be developed for the SSRF soft X-ray beam line for ARPES and PEEM. The effects of DEPU to tune-shift produced by the nonlinear beam dynamics are studied and the results are presented in this paper. The corresponding magnet field shimming technology to reduce these effects is also investigated. | ||
| TUPPC077 | Numerical Study of Beam Trapping in Stable Islands for Simple 2D Models of Betatronic Motion | 1350 |
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| An essential ingredient for the proposed Multi-Turn Extraction (MTE) at the CERN PS is the beam trapping in stable islands. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, the splitting process is studied quantitatively by means of numerical simulations performed on 2D model representing the horizontal non-linear betatronic motion. The results are reviewed and discussed in details. | ||
| TUPPC078 | Proposal of an Inverse Logarithm Scaling Law for the Luminosity Evolution | 1353 |
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| A scaling law for the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers, about ten years ago. It was showed that dynamic aperture has a logarithmic dependence on time, which would be suggested by some fundamental theorems of the theory of dynamical systems. Such a scaling law was recently extended also to the intensity evolution in a storage ring. In this paper, inspired by these results, and inverse logarithm scaling law for the luminosity in a circular collider is proposed. The law is then tested against the data from the LHC physics runs and also with some examples from other machines. The results are presented and discussed in details. | ||
| TUPPC079 | Tracking LHC Models with Thick Lens Quadrupoles: Results and Comparisons with the Standard Thin Lens Tracking | 1356 |
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| So far, the massive numerical simulation studies of the LHC dynamic aperture were performed using thin lens models of the machine. This approach has the clear advantage of speed, but it has also the disadvantage of requiring re-matching of the optics from the real thick configuration to the thin one. Furthermore, as the figure-of-merit for the re-matching is the agreement between the beta-functions for the two model, while the quadrupole gradients are left free parameters, the effect of the magnetic multipoles might be affected by this approach and in turn the dynamic aperture computation. In this paper the new approach is described and the results for the dynamic aperture are compared with the old approach, including detailed considerations on the CPU-time requirements. | ||
| TUPPC080 | Investigations of Scaling Laws of Dynamic Aperture with Time for Numerical Simulations including Weak-Strong Beam-Beam Effects | 1359 |
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| A scaling law describing the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers about ten years ago. It was shown that dynamic aperture has a logarithmic dependence on time, which would be suggested by some fundamental theorems of the theory of dynamical systems. So far, such a law was applied to single-particle effects only, i.e., the only source of non-linear effects was the magnetic imperfections. In this paper an attempt is made to extend the scaling law to the case of weak-strong beam-beam effects. The results of numerical simulations performed, including both non-linear magnetic imperfections and weak-strong beam-beam effects, are presented and discussed in detail. | ||
| TUPPC081 | First Experimental Observations from the LHC Dynamic Aperture Experiment | 1362 |
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| Following intensive numerical simulations to compute the dynamic aperture for the LHC in the design phase, the successful beam commissioning and the ensuing beam operations opened the possibility of performing beam measurements of the dynamics aperture. In this paper the experimental set-up and the first observations based on the few experimental sessions performed will be presented and discussed in detail. | ||
| TUPPC082 | Non-linear Beam Dynamics Tests at the CERN PS in the Framework of the Multi-turn Extraction | 1365 |
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| In the framework of the CERN PS Multi-Turn Extraction several campaigns of measurements probing the non-linear beam dynamics have been carried out. These measurements range from the measurement of non-linear chromaticity to phase space portraits, de-coherence and re-coherence measurements, secondary island tune etc. In this paper these measurements will be reviewed and the results presented and discussed in details. | ||
| TUPPC086 | Conceptual Design of the CLIC damping rings | 1368 |
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| The CLIC damping rings are designed to produce unprecedentedly low-emittances of 500 nm and 5 nm normalized at 2.86 GeV, in all beam dimensions with high bunch charge, necessary for the performance of the collider. The large beam brightness triggers a number of beam dynamics and technical challenges. Ring parameters such as energy, circumference, lattice, momentum compaction, bending and super-conducting wiggler fields are carefully chosen in order to provide the target emittances under the influence of intrabeam scattering but also reduce the impact of collective effects such as space-charge and coherent synchrotron radiation. Mitigation techniques for two stream instabilities have been identified and tested. The low vertical emittance is achieved by modern orbit and coupling correction techniques. Design considerations and plans for technical system, such as damping wigglers, transfer systems, vacuum, RF cavities, instrumentation and feedback are finally reviewed. | ||
| TUPPC090 | Beam Physics of Integrable Optics Test Accelerator at Fermilab | 1371 |
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Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. Fermilab's Integrable Optics Test Accelerator is an electron storage ring designed for testing advanced accelerator physics concepts, including implementation of nonlinear integrable beam optics and experiments on optical stochastic cooling. The machine is currently under construction at the Advanced Superconducting Test Accelerator facility. In this report we present the goals and the current status of the project, and describe the details of machine design. In particular, we concentrate on numerical simulations setting the requirements on the design and supporting the choice of machine parameters. |
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| TUPPC091 | Simulation of Colliding Beams with Feedback in LHC | 1374 |
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Funding: This work supported partially by the US LHC Accelerator Research Program (LARP) of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Beam-beam effects impose restrictions on beam and beam optical parameters as they may degrade the luminosity and the emittance or cause coherent instabilities and particle loss. In the planned High Luminosity Large Hadron Collider (HL-LHC), beam-beam effects will significantly affect the beams because of unprecedented beam parameters and new features like crab cavities or elliptical beam cross sections at the interaction points. Noise from various sources can further worsen the situation. Therefore investigations are required to identify limitations of possible HL-LHC layouts. The impact of beam-beam effects on the beam dynamics is investigated by virtue of particle tracking simulations. Using the code BeamBeam3D and the strong-strong collision model, simulations including perturbations by noise and LHC's feedback system, an important means to mitigate transverse emittance growth due to coherent beam excitation, were carried out. The impact of numerical noise on the emittance in simulations and the state of the feedback modeling are presented. |
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| TUPPC094 | Experimental Observations of Large-amplitude Solitary Waves in Electron Beams | 1377 |
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Funding: Work funded by the US Dept. of Energy Offices of Fusion Energy Sciences and High Energy Physics and Fusion Energy Sciences, and by the Dept. of Defense Office of Naval Research. The longitudinal dynamics of space charge dominated beams plays an important role in particle accelerators and other applications such as heavy ion fusion and free electron lasers (FELs). All beams are space-charge dominated near the source. Furthermore, the longitudinal profile is not necessarily an ideal mathematical function. By means of experiments on the University of Maryland Electron Ring (UMER), we studied how a perturbation to the line charge density could affect the beam propagation. By varying the initial amplitude of the perturbation, we access nonlinear space charge physics. When starting with large-amplitude perturbations, we have observed, for the first time in charged particle beams, solitary waves for which the nonlinear steepening exactly balances the wave dispersion, leading to persistent waves that preserves their shape over a long distance. This paper presents the results of the soliton experiments, including systematic studies of the dependence of the soliton propagation on beam current, perturbation level and width. The data is compared with theory and simulation. |
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| TUPPC096 | Optimization of the Dynamic Aperture for SPEAR3 Low-emittance Upgrade | 1380 |
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| A low emittance upgrade is planned for SPEAR3. As the first phase, the emittance is reduced from 10nm to 7nm without addition magnets. A further upgrade with even lower emittance will require a damping wiggler. There is a smaller dynamic aperture for the lower emittance optics due to the stronger nonlinearity. A Multi-Objective Genetic Optimization (MOGA) code is used to maximize the dynamic aperture. Both the dynamic aperture and beam lifetime are optimized simultaneously. Various configurations of the sextupole magnets have been studied in order to find the best configuration. The betatron tune also can be optimized to minimize resonance effects. The optimized dynamic aperture increases 15% from the normal case and the life time increases from 15 hours to 17 hours. It is important that the increase of the dynamic aperture is mainly in the beam injection direction. Therefore the injection efficiency will benefit from this improvement. | ||
| TUPPC097 | Computational Modeling of Electron Cloud For MEIC | 1383 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. This work is the continuation of our earlier studies on electron cloud (EC) simulations reported in IPAC'11 for the medium energy electron-ion collider (MEIC) envisioned at JLab beyond the 12 GeV upgrade of CEBAF. In this paper, we will study the EC saturation density in various MEIC operations scenarios to calculate details of the EC-induced wakefield to establish more stringent bounds on instability thresholds and determine whether EC mitigation, such as NEG coatings or solenoid fields, should be considered in the MEIC design. |
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| TUPPC098 | Electron Polarization in the Medium-Energy Electron-Ion Collider at JLAB | 1386 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A key feature of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab is high polarization (over 80%) of the electron beam at all collision points for the particle physics program. The equilibrium electron polarization is arranged to be vertical in the arcs of the figure-8 collider ring of the MEIC and anti-parallel to the arc dipole magnetic fields, in order to take advantage of the preservation of polarization by the Sokolov-Ternov (S-T) effect. Longitudinal polarization is achieved at collision points by utilizing energy-independent universal spin rotators each of which consists of a set of solenoids and dipoles placed at the end of an arc. The equilibrium beam polarization and its lifetime depend on competition between the S-T effect and radiative depolarization. The latter must be suppressed by spin matching. This paper reports on investigations of polarization in the MEIC electron collider ring and a preliminary estimate of beam polarization from calculations using the code SLICK. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. |
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| TUPPC099 | Optimization of Chromaticity Compensation and Dynamic Aperture in MEIC Collider Rings | 1389 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by US DOE STTR grant DE-SC0006272. The conceptual design of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab relies on an ultra-small beta-star to achieve high luminosities of up to 1034 cm-2s−1. A low-beta insertion for interaction regions unavoidably induces large chromatic effects that demand a proper compensation. The present approach of chromatic compensation in the MEIC collider rings is based on a local correction scheme using two symmetric chromatic compensation blocks that includes families of sextupoles, and are placed in a beam extension area on both sides of a collision point. It can simultaneously compensate the first order chromaticity and chromatic beam smear at the IP without inducing significant second order aberrations. In this paper, we investigate both the momentum acceptance and dynamic aperture in the MEIC ion collider ring by considering the aberration effects up to the third order, such as amplitude dependent tune shift. We also explore the compensation of the third order effects by introducing families of octupoles in the extended beam area. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by US DOE STTR grant DE-SC0006272. |
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| TUPPC100 | On Quantum Integrable Systems | 1392 |
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Funding: This research is sponsored by Oak Ridge National Lab, under Contract No. DE-AC05-00OR22725, and Fermi National Lab, under Contract No. DE-AC02-07CH11359. Many quantum integrable systems are obtained using an accelerator physics technique known as Ermakov (or normalized variables) transformation. This technique was used to create classical nonlinear integrable lattices for accelerators and nonlinear integrable plasma traps. Now, all classical results are carried over to a nonrelativistic quantum case. |
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| TUPPC101 | A Model of the AGS Based on Stepwise Ray-Tracing Through the Measured Field Maps of the Main Magnets | 1395 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Two dimensional mid-plane magnetic field maps of two of the main AGS magnets were produced, from Hall probe measurements, for a series of different current settings. The analysis of these data yielded the excitation functions and harmonic coefficients of the main magnets [BNL TN 424 & TN 429] which have been used so far in all the models of the AGS. The constant increase of computation power makes it possible today to directly use stepwise ray-tracing through these measured field maps with a reasonable computation time. We describe in detail how these field maps have allowed generation of models of the 6 different types of AGS main magnets, and how they are being handled with the Zgoubi ray-tracing code. We give and discuss a number of results so obtained regarding both beam and spin dynamics in the AGS, and provide comparisons with other numerical and analytical modeling methods. |
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| TUPPC102 | Simulation Study of Beam-beam Effects in Ion Beams with Large Space Charge Tuneshift | 1398 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. During low-energy operations with gold-gold collisions at 3.85 GeV beam energy, significant beam lifetime reductions have been observed due to the beam-beam interaction in the presence of large space charge tuneshifts. These beam-beam tuneshift parameters were about an order of magnitude smaller than during regular high energy operations. To get a better understanding of this effect, simulations have been performed. Recent results are presented. |
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| TUPPC103 | Ion Bunch Length Effects on the Beam-beam Interaction and its Compensation in a High-luminosity Ring-ring Electron-ion Collider | 1401 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. One of the luminosity limits in a ring-ring electron-ion collider is the beam-beam effect on the electrons. In the limit of short ion bunches, simulation studies have shown that this limit can be significantly increased by head-on beam-beam compensation with an electron lens. However, with an ion bunch length comparable to the beta-function at the IP in conjunction with a large beam-beam parameter, the electrons perform a sizeable fraction of a betatron oscillation period inside the long ion bunches. We present recent simulation results on the compensation of this beam-beam interaction with multiple electron lenses. |
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