Paper | Title | Page |
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MOPGW008 | Transparent Injection for ESRF-EBS | 78 |
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The commissioning of the ESRF-EBS storage ring will start in December 2019 ultimately providing a horizontal emittance of 130 pm, 30 times lower than the present one. Due to the reduced beam lifetime top-up operation will be required for all operating modes. Transparent injection, i.e. with negligible perturbations on the stored beam, is necessary to allow continuous data acquisition for beam lines experiments. Several options have been considered at ESRF to reduce these perturbations down to a fraction of the rms beam size: i) new kickers power supplies with slow ramping time to facilitate active compensation are under development and will be implemented in the coming years ii) in parallel, long term solutions using non-linear kickers and longitudinal on-axis injection have been investigated. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW008 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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MOPGW014 | Developing Beam Optics for the BESSY VSR Project | 94 |
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At BESSY II due to the continuously increasing interest in short pulse operation, a major upgrade of the ring will enable simultaneous storage of long and short bunches. This Variable pulse-length Storage Ring (VSR) will be achieved by the installation of additional superconducting high gradient cavities. The cavities will be assembled into one cryomodule in one of the straights of the storage ring. As this module needs more space then initially assumed, one possible solution is to remove two quadrupoles to gain available installation length. The quadrupoles were switched off in simulations and the lattice was optimized with regard to the linear order. The best solution found was transferred to the storage ring, where storage of high current with reasonable injection efficiency and lifetime was possible. The proposed optics has to be further optimized in terms of nonlinear beam dynamics, but has shown that an available installation length can be increased. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW014 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW015 | Notes on Linear Theory of Coupled Particle Beams with Equal Eigenemittances | 98 |
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We consider some aspects of the linear theory of coupled particle beams with equal eigenemittances and compare them with the one dimensional Courant-Snyder theory. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW015 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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MOPGW016 | Straightness Correction of Ballistic Trajectories | 101 |
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We describe procedure for straightness correction of ballistic trajectories in the presence of BPM noise and unknown BPM offsets. We also discuss applicability of this method to the beam based alignment of the European XFEL undulators. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW016 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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MOPGW022 | Achromatic Isochronous Mode of the ESR at GSI | 124 |
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The isochronous optics of the ESR is a unique ion-optical setting in which the ring is operated as a Time-of-Flight Mass-Spectrometer and is used for direct mass measurements of short-lived exotic nuclei. The present isochronous optics had been performed only making a negative dispersion in the straight sections of the ESR of about -7 m. This negative dispersion makes the injection into the ESR very complicated and strict the transmission of the ions in the ring. Moreover, the non-achromatism of the ESR brings a supplementary uncorrectable first-order transverse contribution to the revolution time. In order to make the ESR achromatic, to improve injection and the isochronicity a new achromatic isochronous optics has been calculated and will be presented here in details. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW022 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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MOPGW023 | An Algorithm for Automated Lattice Design of Transfer Lines | 127 |
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Since the last 20 years, modern heuristic algorithms and machine learning have been increasingly used for several purposes in accelerator technology and physics. Since computing power has become less and less of a limiting factor, these tools have become part of the physicist community’s standard toolkit. This paper describes the construction of an algorithm that can be used to generate an optimised lattice design for transfer lines under the consideration of restrictions that usually limit design options in reality. The developed algorithm has been applied to the existing SIS18 to HADES transfer line in GSI. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW023 | |
About • | paper received ※ 28 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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MOPGW024 | Measurements of the GSI Transfer Beam Lines Ion Optics | 131 |
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GSI High Energy Beam Transfer lines (HEST) link the SIS18 synchrotron with two storage rings (Experimental Storage Ring and Cryring) and six experimental caves. The recent upgrades to HEST beam instrumentation enables precise measurements of beam properties along the lines and allow for faster and more precise beams setup on targets. Preliminary results of some of the measurements performed during runs in 2018 and 2019 are presented here. The focus is on response matrix measurements and quadrupole scans performed on HADES beam line. The errors and future improvements are discussed. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW024 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019 | |
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MOPGW026 | Transfer Line Optics Design Using Machine Learning Techniques | 139 |
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Optimization of transfer line optics is essential for delivering high quality beams to the experimental areas. This type of optimization is usually done by hand and relies on the experience of operators. The nature of this task is repetitive though highly complex. Besides optimizing the beam quality at the experiments this task is often accompanied by secondary objectives or requirements such as keeping the beam losses below an acceptable threshold. In the past years Deep Learning algorithms have experienced a rapid development and gave rise to various advanced software implementations which allow for straightforward usage of corresponding techniques, such as automatic differentiation and gradient backpropagation. We investigate the applicability and performance of these techniques in the field of transfer line optics optimization, specifically for the HADES beamline at GSI, in form of gradient-based differentiable simulators. We test our setup on results obtained from MADX simulations and compare our findings to different gradient-free optimization methods. Successfully employing such methods relieves operators from the tedious optimization tasks. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW026 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW027 | Design Considerations for Permenant Magnetic Quadrupole Triplet for Matching Into Laser Driven Wake Field Acceleration Experiment at SINBAD | 143 |
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SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility aims to produce ultrashort bunches (sub-fs) at ~100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The LWFA experiment demands β functions to be of the order of 1 mm to reduce energy spreads and emittance growth from nonlinearities. Matching such a space charge dominated beam to such constraints with conventional electromagnets is challenging. A Permanent Magnetic Quadrupole (PMQ) triplet is one promising focusing strategy. In this paper, we investigate the performance of a PMQ triplet to fit the requirements of the electron beam properties in a plasma cell and discuss the realizable phase spaces for the LWFA experiment planned at SINBAD. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW027 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW029 | Preliminary Study of Bunch Compression in the Hefei Light Source | 151 |
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Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077), and the National Natural Science Foundation of China(GrantNo.11475167). Short electron bunch has interesting applications in the synchrotron radiation light sources, such as the production of powerful coherent THz radiation, time resolving spectrum analysis, etc. In this work, we are interested in acquiring the short bunch in the storage ring with a small circumference like Hefei Light Source. In this paper, we tried to approach the short bunch in two separate methods: by increasing the higher harmonic cavity voltage and by reducing the momentum compaction factor. The preliminary result and observations are shown and discussed. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW029 | |
About • | paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW040 | Beam Optics Design of the Superconducting Region of the JAEA ADS | 181 |
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The Japan Atomic Energy Agency (JAEA) is proposing an Accelerator Driven Subcritical System (ADS) for the transmutation of the nuclear waste. ADS will consist of a superconducting CW proton linear accelerator of 30MW and a subcritical nuclear reactor core. The main part of the acceleration will take part in the superconducting region using five types of radio frequency cavities. The ADS operation demands a high intensity and reliability of the beam. Therefore, the beam optics design plays a fundamental role to reduce the beam loss, control emittance growth and beam halo. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW040 | |
About • | paper received ※ 17 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW044 | Off-Energy Off-Axis Injection with Pulsed Multipole Magnet Into the HALS Storage Ring | 187 |
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As a future Diffraction-Limited Storage Ring (DLSR) at NSRL, the Hefei Advanced Light Source (HALS) has been proposed and has a great progress in the lattice optimization. The nonlinear dynamics is well designed and shows good performance, which makes it easier for beam injection and gives us more choices to design a more suitable injection scheme. In this paper, a new off-energy off-axis pulsed multipole injection scheme is proposed. The off-energy beam is off-axis injected into the acceptance of the storage ring with one or several pulsed multipole kickers and meanwhile the stored beam is almost unaffected during the injection. The injection acceptance of the storage ring is analyzed and the injection scheme is preliminary designed. A series of tracking simulations are carried out and the results are presented. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW044 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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MOPGW046 | Proton Beam Steering for the Experimental Muon Source at CSNS | 193 |
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Experimental Muon Source (EMuS) is a muon source to be built at China Spallation Neutron Source (CSNS). The EMuS baseline design adopts a stand-alone target sitting in capture superconducting solenoids, and the muon beam is extracted in the forward direction. In the same time the spent protons are also extracted from the target station and guided to an external. Because there is an angle of 15 degrees between the axis of solenoids and the proton direction, the protons will be deviated by the solenoid field. A pair of correction magnets in front of the solenoids is used to align the incoming proton beam to the target and also guide the spent protons to the beam dump. As the target station is design to work at different field level, this increases the complexity of the proton beam transport. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW046 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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MOPGW054 | Study on Spherical Aberration Correction of Solenoid Lens in Ultrafast Electron Diffraction | 213 |
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High electron beam quality is required in Ultrafast Electron Diffraction (UED) to achieve high spatial resolution. However, aberrations mainly induced by solenoid lens will deteriorate the beam quality and limit the resolution. Spherical aberration introduces the largest distortion which is unavoidable in the case of static cylindrically symmetric electromagnetic fields on the basis of Scherzer’s theorem. In order to reduce the spherical aberrations, different models have been designed which are composed of three symmetrical lens and one asymmetrical lens. We obtain the magnetic field distribution and calculate the aberration of each model by OPERA, and the result is that the solenoid without poles has the minimum aberration and meets the design requirement best. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW054 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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MOPGW063 | Beam Dynamics Optimization in Drift Tube Linear Accelerator With Permanent Quadrupole Magnets | 234 |
SUSPFO090 | use link to see paper's listing under its alternate paper code | |
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The research concerns the design of a drift tube linear accelerator (DTL) with permanent quadrupole magnets (PMQ) placed inside some of the drift tubes for focusing. The study was conducted using Comsol Multiphysics software, where electromagnetic fields and particle dy-namics in the cavity were calculated. The proton beam is accelerated up to 10 MeV. Initial beam is assumed to come from Radio Frequency Quadrupole accelerator (RFQ). Mathematical methods of control theory are used for particles dynamics optimization. Different focusing lattices are examined and variations of the gradient of the magnetic lenses are analyzed with respect to output beam parameters. Effectiveness of the optimization is estimated by the transmission rate and the emittance growth. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW063 | |
About • | paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW067 | On Coordinate Systems in Beam Dynamics | 243 |
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Any description of the beam dynamics calculation and simulation relies on the proper choice of a coordinate system in order to minimize the computational complexity and to apply different level of approximations in the calculations. This need generates a large number of reference systems, especially to describe the longitudinal dynamics of a particle beam like(z, z′),(t,∆P/P),(z, φ), etc. In this paper we summarize the rules to change coordinates systems, which system is canonical and how the Hamiltonian of the beam transforms according to the chosen coordinate system. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW067 | |
About • | paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW072 | Reconfiguration of SPS Landau Octupole Circuits to Minimise Second Order Chromaticity | 262 |
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In the SPS Q20 optics presently used for LHC beams, the Landau octupole families of the SPS (LOF and LOD circuits) generate large second order chromaticity due to the relatively high dispersion at their locations. Since the induced second order chromaticity results in enhanced losses due to the large incoherent tune spread, these octupoles cannot be used for mitigating transverse instabilities for LHC beams. A new cabling scheme was proposed, exploiting additional octupoles that were already installed in the machine but not used, which allows minimizing the induced second order chromaticity in both the Q20 optics used for LHC beams, as well as the original SPS optics used for fixed target beams. This paper summarises the optics calculations as well as the experimental verification of the reduced chromatic detuning of the new octupole scheme. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW072 | |
About • | paper received ※ 12 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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MOPGW080 | Optics Measurements in the CERN PS Booster Using Turn-by-Turn BPM Data | 285 |
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As part of the LHC Injector Upgrade Project the injection of the CERN PS Booster will be changed to increase intensity and brightness of the delivered beams. The new injection scheme is likely to give rise to beta beating above the required level of 5\% and new measurements are required. Achieving accurate optics measurements in PSB lattice is a challenging task that has involved several improvements in both hardware and software. This paper summarizes all the improvements that have been performed in the optics measurement acquisition system together with a brief summary of the first results obtained. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW080 | |
About • | paper received ※ 11 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW085 | Intensity Dependent Effects in the ILC BDS | 305 |
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The International Linear Collider (ILC) is an electron-positron collider being considered for the post-LHC era. Its Beam Delivery System (BDS) receives the beam from the main linac. This beam is then focused to the nanometer scale after going through collimators, beam diagnostic systems, strong magnets, etc. Effects such as wakefields due to resistive-wall, BPMs and collimators make the system very sensitive to the beam intensity. Understanding these effects is crucial in order to demonstrate that the nominal beam size at the Interaction Point (IP) can be reached in realistic scenarios. In this paper, results of the intensity dependence effects in the ILC BDS, simulated with PLACET, are presented. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW085 | |
About • | paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW086 | Intensity Dependent Effects at ATF2, KEK | 308 |
SUSPFO104 | use link to see paper's listing under its alternate paper code | |
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The Accelerator Test Facility 2 (ATF2) at KEK is a prototype for the Final Focus Systems of the future e+e− linear colliders, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). In this paper both simulation and experimental results are presented with special emphasis on intensity-dependent effects. The importance of these effects is shown using the PLACET code and realistic ATF2 machine simulations (including beam jitter, misalignment, wakefield, Beam Based Alignment (BBA) correction, …). The latest experimental results are also presented, in particular the impact of the beam intensity on the beam size at the IP. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW086 | |
About • | paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW090 | Alignment of a Magnetic Lattice Based on Particle Tracking | 324 |
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In calculations based on particle tracking in 3D magnetic field maps alignment of the components of a magnetic lattice is essential to obtain desired properties of beam optics. In this contribution we propose a method to control and correct misalignments during the process of the beam optics design. These misalignments would result from overlapping fringe fields of different field maps. The 3D field maps are obtained from the software for electromagnetic calculations OPERA. The full 3D map is saved in the tracking coordinate system and a ROOT (An Object Oriented Data Analysis Framework) ntuple is then created for analysis. The trajectory of the reference particle is calculated by means of OPAL - open source code developed at the Paul Scherrer Institut (PSI). The transverse magnetic field profiles allow possible misalignments to be precisely determined and the corresponding corrections to be calculated. Moreover, the multipole content in discrete locations along the lattice can be controlled by performing a polynomial fit, which calculates the magnetic field harmonics with respect to the reference track. This method was used at PSI for a design of a model of the magnetic lattice for a superconducting gantry for proton therapy with a large momentum acceptance.
*An Object Oriented Data Analysis Framework - http://root.cern.ch |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW090 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW093 | Optics Calibration for Routine Operations In Taiwan Photon Source | 335 |
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To ensure a stable performance of Taiwan Photon Source (TPS), we perform the calibration of accelerator optics using LOCO (Linear Optics from Closed Orbit) technique every month. After the optics and coupling corrections, the rms beta beatings in both planes are reduced to less than 1%. The emittance coupling ratio is also restored to within the design value. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW093 | |
About • | paper received ※ 06 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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MOPGW094 | First Machine Developments Result with HL-LHC Crab Cavities in the SPS | 338 |
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Crab cavities are a critical component within the High Luminosity upgrade project for the Large Hadron Collider (HL-LHC). It is foreseen to use crab cavities in order to compensate the geometric luminosity reduction factor (reduction of the luminous region at the Interaction Point [IP]) due to the beam crossing angle (required for minimizing the impact of the long range beam-beam effects on the single particle beam dynamics) and increase the number of collisions per bunch crossing. In 2018 the first beam tests of crab cavities with protons were performed in the Super Proton Synchrotron (SPS) at CERN. Two vertical superconducting cavities of the Double Quarter Wave (DQW) type were fabricated and installed in the SPS to verify some key components of the cavity design and operation. This paper will present some of the first results relating to the proton beam dynamics in the presence of crab cavities. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW094 | |
About • | paper received ※ 25 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW097 | SOLEIL Storage Ring Upgrade Performance in Presence of Lattice Imperfections | 350 |
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The design for the upgrade of the SOLEIL third generation light source is progressing. At the present stage, different lattices are evaluated as possible candidates for the storage ring upgrade and an important factor for the comparison of their performances is the robustness against lattice imperfections. The strategy for this study consists in defining a set of misalignments of the lattice elements and field errors of the magnets that are expected to be attained after the commissioning, applying them to the lattice models and correcting them using response matrix based techniques. A dedicated algorithm was developed in Accelerator Toolbox in order to accomplish this procedure and compare the different lattices. In this paper the results of this study at the current state are presented, including the considered lattice imperfections, the correction method applied and the final performance of the lattices. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW097 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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MOPGW098 | Iterative Trajectory-Correction Scheme for the Early Commissioning of Diffraction-Limited Light Sources | 353 |
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The commissioning of diffraction-limited light sources will be significantly affected by the fact that typical lattice designs rely on very strong focussing elements in order to achieve the small emittance goals. Especially in the early-commissioning phase this can render procedures successfully used in the commissioning of existing third-generation light sources ill-suited for the application to these new machines. In this contribution we discuss an iterative approach to the early trajectory correction, based on the well-known pseudo-inversion of a trajectory-response matrix. Measuring this matrix during early commissioning can be cumbersome, so that an algorithm working with the model response matrix of the lattice is desirable. We discuss the stability of the iteration in the presence of lattice errors, resulting in differences between the actual and the model response matrix. Further, Tikhonov regularization is investigated as a means to trade off the RMS trajectory variation against the strength of the required corrector kicks. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW098 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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MOPGW100 | Bypass Design for Testing Optical Stochastic Cooling at the Cornell Electron Storage Ring (CESR) | 360 |
SUSPFO048 | use link to see paper's listing under its alternate paper code | |
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Funding: NSF-1734189 DGE-1650441 Optical Stochastic Cooling (OSC) is a promising method for cooling very dense stored particle beams through the interference of radiation created in an upstream ’pickup’ wiggler and a downstream ’kicker’ wiggler. By correlating a particle’s path length via a bypass between the two wigglers with its betatron coordinates in the pickup, the particle will receive a kick in energy which, through coupling introduced by non-zero horizontal dispersion in the kicker, can reduce its betatron amplitude, thus cooling the beam. A proof-of-principle test of this technique is being planned at the Cornell Electron Storage Ring (CESR). In addition to maintaining standard requirements such as a large dynamic aperture and acceptable lattice functions throughout the ring, the design of the bypass is guided by the mutually competing goals of maximizing the cooling rate while maintaining a sufficiently large cooling acceptance with properly-corrected nonlinearities. We present a design of such a bypass and ring optics so as to best achieve these objectives. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW100 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019 | |
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MOPGW104 | Equilibria and Synchrotron Stability in Two Energy Storage Rings | 364 |
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In a dual energy storage ring, the electron beam passes through two loops at markedly different energies EL, and EH, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ’Storage Ring’ (SR) equilibrium and ’Energy Recovery Linac’ (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and ERL equilibrium mode is the case where RF in two beam passes nearly cancels. Calculations based on linear transfer matrix formalism show that longitudinal stability exists for both SR mode and ERL mode in two energy storage rings. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW104 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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MOPGW110 | Study of the Beam Current Effects on the NSLS-II Storage Ring Optics Using Turn-by-Turn Data | 375 |
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These days, the techniques using the turn-by-turn data are well developed in analyzing the accelerator optics. We compared the data for the low and high beam currents and studied the beam current effects on the storage ring lattice optics. Also, by comparing the local transfer matrices, we analyzed the amounts of the impacts on the linear optics around the ring. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW110 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW111 | Start to End Simulation on Beam Dynamics in Coherent Electron Cooling Accelerator | 379 |
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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. A Coherent electron Cooling (CeC) has a potential of substantial reducing cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. In a CeC system, a high quality electron beam is generated, propagated and optimized through a beam line which was carefully designed with consideration of space charge effect, wakefields and nonlinear dynamics such as coherent synchrotron radiation and chromatic aberration. In this paper, we present our study on the beam dynamics of such a beam line and compare the simulation result with what was measured in experiment. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW111 | |
About • | paper received ※ 17 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW112 | Design of a Bunch Compressor with CSR Suppression to Achieve Hundreds of kA Peak Current | 382 |
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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. A four dipole magnetic chicane is usually used to compress electron bunch to very short in modern accelerators which requires electron beams to have high peak current. The coherent synchrotron radiation (CSR) originated from the strong bending magnets in the chicane could greatly degrade the quality of the electron beam. In this paper, we present our design for a bunch compressing system with 30 to 100 fold in bunch length reduction and at the mean time suppress the effect of CSR on the e-beam’s quality. We discuss and detail the performance of such a compressor for potential FACET-II upgrade. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW112 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW114 | Bayesian Approach for Linear Optics Correction | 390 |
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With a Bayesian approach, the linear optics correction algorithm for storage rings is revisited. In modern ring-based accelerators, optics corrections are determined from repetitive measurements which help identify systematic and random quadrupole errors in presence of various measurement noises. This process is a multivariate nonlinear regression problem driven by either a completed lattice model or a Jacobian matrix. Starting from the Bayes’ theorem, ’likelihood functions’ and ’prior probability’ distributions are extracted from a complete linear optics model. Under some assumptions, the least square algorithm and then the Jacobian matrix approach can be re-derived. The coherence of the correction algorithm is ensured through specifying a self-consistent regularization coefficient to prevent overfitting. Optimal weights for different correction objectives are obtained based on their measurement noise level. A new technique has been developed to resolve degenerated quadrupole errors when observed at a few select BPMs. A necessary condition of being distinguishable is that their optics response vectors seen at these specific BPMs should be near-orthogonal. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW114 | |
About • | paper received ※ 18 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW115 | A Cross-Cell Interleaved Nonlinear Lattice for Potential NSLS-II Upgrade | 393 |
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An interleaved sextupole scheme using cross-cell betatron phase cancellation technique is adopted as a candidate for the future NSLS-II upgrade lattice. The lattice uses as many NSLS-II installed magnets as possible, including 30 dipoles, to compose a triple bend achromat lattice. A 300 pm.rad horizontal beam emittance is achieved. The emittance can be further reduced to around 200 pm rad with damping wigglers. Various design concepts used in modern 4th-generation light sources, such as adopting longitudinal gradient dipoles and anti-bend scheme, are incorporated into the design as well. The betatron phase-advance between sextupoles is designed to have a cross-cell interleaving cancellation pattern in the transverse planes. The dynamic aperture is big enough for the conventional off-axis top-off injection. At the same time, a large energy acceptance looks promising to ensure a sufficiently long beam lifetime. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW115 | |
About • | paper received ※ 12 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW123 | Electromagnetic Study and Measurements of the iRCMS Cell | 403 |
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Funding: BNL Contract TSA-NF-18-80 The ion Rapid Cycle Medical Synchrotron (iRCMS) * will provide proton and C ion bunches with maximum energy 270 MeV and 450 MeV/u respectively at a frequency of 15 Hz for treating cancerous tumors. One of the six cells of the iRCMS has been designed, built and magnetic field measurements have been performed. We will present results from the static and AC electromagnetic study of the iRCMS cell and compare the measured magnetic fields with those calculated using the OPERA computer code **. In addition the beam optics of the cell will be calculated based on the experimental fields using the zgoubi computer code *** and compared with the designed beam optics. * D. Trbojevic, iRCMS Magnet Review, BNL, Sept. 6, 2012 (unpublished) ** OPERA computer code https://operafea.com/ *** The zgoubi computer code https://www.bnl.gov/isd/documents/79375.pdf |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW123 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW124 | Coherent Synchrotron Radiation Simulation for CBETA | 406 |
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CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return beamline accepting all energies from 42 to 150 MeV. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving vacuum chamber shielding and increasing bunch length are being investigated. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW124 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPTS081 | Design of the Transferline to the ESS Target and Beam Dump at Reduced Beam Energy | 1034 |
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The European Spallation Source (ESS) linac transfer-lines to the target and beam dump are designed for the 2 GeV beam energy. The commissioning and operation of the accelerator will start at a reduced energy of 571 MeV with the high beta part of the linac unpowered. The beam power at this energy is still above 1 MW and a proper transport from the last accelerating cavity to the target is essential. Beam dynamics design of the High Energy Beam Transport (HEBT) and Accelerator to Target (A2T) are studied based on this reduced energy in this paper, including phase advance optimization and rematch. Among the factors which are analyzed are the envelope and beam size on the target which are kept close to their values at 2 GeV and losses along the linac and the transfer lines. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS081 | |
About • | paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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MOPTS112 | Matrix Approach to Decouple Transverse-Coupled Beams | 1144 |
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Funding: Work supported by the National Key Research and Development Program of China (grant number 2016YFC0105408). Transverse emittances, especially vertical emittance, are strictly required in the synchrotrons with multi-loop injection. Transverse emittances easily grow up if transverse beam phase spaces are coupled. The growth of the transverse emittance can be restained by decoupling the beam phase spaces. Based on the transfer matrix calculation, it can be theoretically proved that the decoupling can be implemented for general situations. A minimum number of rotated quadrupoles required for decoupling is given. Two quadrupoles can decouple the beam and suppress its emittance growth to 1% in the coupling DTL case. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS112 | |
About • | paper received ※ 28 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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TUZPLS1 |
Microbunch Rotation and Coherent Undulator Radiation From a Kicked Electron Beam | |
SUSPFO130 | use link to see paper's listing under its alternate paper code | |
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Most X-ray Free Electron Lasers (FELs) emit linearly polarized X-ray pulses. Recently, a device called the Delta undulator has been installed at the Linac Coherent Light Source (LCLS) to provide tuneable polarization. The electron beam is first microbunched by the LCLS normal undulators, then the microbunched beam is kicked prior to the Delta undulator, and an intense circularly polarized X-ray pulse is generated in the Delta undulator towards the kicked direction and is spatially separation from the linearly polarized radiation from upstream undulators. Coherent off-axis radiation is usually strongly suppressed because the microbunches themselves cannot rotate. The talk will show that microbunches can in fact rotate towards the new direction of travel if the kick is applied in a quadrupole focusing channel and also will clarify characteristics of the coherent undulator radiation from a tilted microbunch in the far-field and will compare simulations with experiments. This microbunch rotation can explain the unexpectedly large amount of off-axis radiation that was observed during Delta undulator experiments at LCLS and may have other applications to the advanced X-ray manipulations. | ||
Slides TUZPLS1 [14.027 MB] | ||
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TUZPLS2 | Beam Dynamics Study in the HEPS Storage Ring | 1203 |
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The High Energy Photon Source (HEPS) is the first high-energy diffraction-limited storage ring (DLSR) light source to be built in China, with a natural emittance of a few tens of pm rad and a circumference of 1360.4 m. After 10 years’ evolution, the accelerator physics design of the HEPS has been basically determined, with the ring consisting of 48 hybrid-7BAs with anti-bends and super-bends. This paper will discuss the accelerator physics studies of the HEPS storage ring, covering issues of lattice design, nonlinear optimization, collective effects, error correction, insertion devices, etc. | ||
Slides TUZPLS2 [9.517 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZPLS2 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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WEYYPLS1 | Muon G-2: An Interplay between Beam Dynamics and a Muon Decay Experiment at the Precision Frontier | 2266 |
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Funding: This work has been partially funded by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The Muon g-2 Experiment at Fermilab (E989) will use the higher proton flux delivered by the Fermilab accelerator complex and improvements to the experimental apparatus to measure the anomalous magnetic moment of the muon to unprecedented precision. In addition to the increased statistics beyond the most recent measurement, the experiment relies on detailed understanding of the beam dynamics in the experiment’s storage ring as well as the incoming muon beam properties for proper assessments of systematic errors in the data analysis. Modeling and measurements of beam and storage ring properties, from proton targeting to muon storage, produce a unique unification of particle beam physics with a high energy physics experiment. Here the beam dynamics issues and analysis techniques essential to the g-2 experiment are presented and discussed. |
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Slides WEYYPLS1 [12.990 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLS1 | |
About • | paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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WEYYPLS2 | First Experimental Measurements of the Caustic Nature of Trajectories in Bunch Compressors | 2270 |
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Theoretical advancements describing density perturbations in accelerated charge particle beams, known as caustics, has been recently developed * This proceeding describes the first experimental measurements of the caustic nature of charged particle trajectories in a particle accelerator. Caustics by their nature are discontinuities that result from small continuous perturbations of an input. Under certain conditions, small density modulations will reliably produce striking changes in the corresponding output current profile. These current modulations can shift alone the bunch with varying higher-order longitudinal dispersion. The MAX IV linac double-bend achromats provide the perfect test bed for experimentally verifying how the caustic lines evolve. The natural amplification of small perturbations makes caustics an attractive diagnostic tool, and effective tool for characterise the bunch compressors. This approach also allows us to modify and improve the longitudinal charge profile, removing current spikes or creating tailor shaped current profiles.
* T.K.Charles et. al. Phys. Rev. Accel. Beams 19, 104402 |
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Slides WEYYPLS2 [5.402 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLS2 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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WEPTS100 | The ESR Closed Orbit Calculation and Simulation | 3349 |
SUSPFO031 | use link to see paper's listing under its alternate paper code | |
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The commissioning of the ESR with a new control system based on the LSA (LHC System Architecture) has started recently. This new control system is under development and considers all aspects of the expected functionality to operate the GSI/FAIR accelerators and incorporates the present GSI controls infrastructure*. Two years ago, the old control system which was based on outdated computers and operating system, was discontinued. So, both the heavy ion synchrotron SIS-18 and the Experimental Storage Ring (ESR) operation from now on have to be performed with the new FAIR control system. In order to introduce an improved model to the control system change, new calculations and simulations for SIS and ESR are necessary. In this paper we summarize the results of closed orbit calculations for the ESR which are done with three different codes, namely: ELEGANT*, MAD-X and MIRKO. Also, because the results of ELEGANT and MAD-X in this issue are similar to each other, we present ELEGANT results in the report.
* R. Bär, DEVELOPMENT OF A NEW CONTROL SYSTEM FOR THE FAIR ACCELERATOR COMPLEX AT GSI. Kobe. ** Borland, M., elegant: A Flexible SDDS-Compliant Code for Accelerator Simulation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS100 | |
About • | paper received ※ 29 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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