BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
The design and measurement of the NSLS-II ring quadrupoles prototypes are presented. These magnets are part of a larger prototype program described in [1]. Advances in software, hardware, and manufacturing have led to some new level of insight in the quest for the perfect magnet design. Three geometric features are used to minimize the first three allowed harmonics by way of optimization. Validations through measurement and confidence levels in calculations are established.
BNL, Upton, Long Island, New York
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Funding: Work Supported by the United States Department of Energy, Contract No. DE-AC02-98CH10886.
The International Design Study for the Neutrino Factory (IDS-NF) aims to produce a design report for a neutrino factory. One component of that design is a linear non-scaling fixed-field alternating gradient accelerator (FFAG) that will accelerate to the final energy of 25~GeV. An FFAG is used to reduce the machine cost by maximizing the number of passes made through the RF cavities. We present some design options for this FFAG, individually optimized for cost. We study the addition of nonlinear magnets to the lattice to improve the performance of the lattice and consider the negative effects of doing so.
FZJ, Jülich
A possible solution to avoid the transition energy crossing is the lattice with a negative momentum compaction factor. The developed lattice is based on the resonantly correlated curvature and gradient modulations in arcs with integer tunes in horizontal or both planes, and it called the “resonant” lattice*. This method was adopted for the TRIUMF and Moscow Kaon Factories. It was then applied in the SSC Low Energy Booster, the CERN Neutrino Factory, and in the Main Ring of the Japan Proton Accelerator Research Complex facility. For the superconducting option of High Energy Storage Ring lattice of the FAIR project, the same idea was also accepted, and at last it is one of the candidates for PS2 in CERN as well. Due to special features the idea of “resonant” lattice can be applied for the lattice with the stochastic cooling where the different arcs have the different mixing factors with conservation of the dynamic aperture for whole machine. The “resonant” lattice is appeared to be useful for electron machines where the minimum momentum-compaction factor and the minimum modulation of the dispersion function are both required simultaneously to have a small horizontal emittance.
*Yu. Senichev and A. Chechenin, Journal of Experimental and Theoretical Physics, 2007, v. {10}5, No. 6, p. 1141
BNL, Upton, Long Island, New York
Funding: NSLS-II, Brookhaven National Laboratory
NSLS-II, the third-generation light source which will be built at BNL is designed and optimized for 3 GeV energy, ultra-small emittance and high intensity of 500 mA. It will provide very bright synchrotron radiation over a large spectral range from IR to hard X-rays. Damping wigglers (DWs) are deployed to reduce the emittance of 2 nm by factors of 2-4, as well as for intense radiation sources for users. The linear and nonlinear effects induced by the DWs are integrated into the lattice design. In this paper, we discuss the linear and nonlinear optimization with DWs, and present a solution satisfying the injection and lifetime requirements. Our approach could be applied to the other light sources with strong insertion devices.
IHEP Beijing, Beijing
Funding: Work supported by National Natural Science Foundation of China contract 10725525
The upgraded project of the Beijing Electron-Positron Collider (BEPCII) can be operated not only for high energy physics experiments as a charm factory, but for synchrotron radiation users as a first generation light source. The design of the synchrotron radiation (SR) mode of the BEPCII storage ring keeps all the original beam lines of the BEPC. The lattice based on the layout of the collider can meet all the requirements of the SR users, and the emittance is minimized. Optimization of the SR mode focuses on reducing the effects from wigglers around the ring. Some results from the operations of the SR mode are also given.
JASRI/SPring-8, Hyogo-ken
An ultra-low emittance storage ring with an energy of 6 GeV was proposed as a next generation synchrotron radiation source*. The storage ring has the same circumference as that of SPring-8 storage ring so as to be able to replace the existing storage ring, but has not four long straight sections. Accordingly, the storage ring beam line is slightly different from that of SPring-8 and the positions of photon beam lines are also different from the existing one. To avoid this, a storage ring with four long straight sections has been designed. The beam line position of the new storage ring is the same as the existing one. The storage ring consists of twenty ten-bend achromat cells, four five-bend achromat cells and four long straight sections. The long straight section length is 34.0 m and the short one is 6.6 m. The natural emittance is less than 100 pm-rad. In the paper, the dynamic aperture problem is discussed and the other ring characteristics are presented.
*K. Tsumaki and N. Kumagai, EPAC’06, 3362.
USTC/NSRL, Hefei, Anhui
FEL/Duke University, Durham, North Carolina
Funding: Work supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086 (YKWu), also supported by National Natural Science Foundation of China (No.10175062 and 10575100).
Many modern light source storage rings use a basic magnetic lattice structure consisting of a number of repetitive periodic lattice block, the super periods. The study of one super-period can reveal the dynamical proprieties of the storage ring. Unlike the traditional approach of studying the one-turn map of the storage ring, the work focuses on the study of a super-period lattice, which allows us to gain new insight into the storage ring dynamics using a simpler magnetic structure. In this paper, both analytical and numerical techniques, including Lie Algebra and Normal Form, and particle tracking and frequency analysis, are used to study the nonlinear dynamics of one super-period of a standard double-bend achromat (DBA) and triple-bend achromat (TBA) with two or more nonlinear elements (e.g. sextupoles). The relationship between the super-period dynamics and storage ring dynamics is explored in terms of the global lattice tuning and local lattice selection for straight sections.
H. Hao is currently working as a visiting scholar at Duke University Free Electron Laser Laboratory.
Fermilab, Batavia
MSU, East Lansing, Michigan
St. Petersburg State University, St. Petersburg
Innovations in computer techniques in combination with increased sophistication in modeling are required to accurately understand, design and predict high-energy, and, in particular, the new generation of frontier accelerators for HEP and other applications. A recently identified problem lies in the simulation and optimization of FFAGs and related devices, for which currently available tools provide only approximate and inefficient simulation. For this purpose new tools are being developed within the advanced accelerator code COSY INFINITY to address complex, specific electromagnetic fields, including high-order fringe fields, out of plane fields, edge effects, and general field profiles; tools linked to modern global optimization techniques that can further accommodate the ultra-large emittances of proposed beams to allow efficient probing of very high dimensional parameter space. This new set of tools based on modern techniques and simulation approaches will be furnished with modern GUI-based user interfaces.
NSRRC, Hsinchu
The design work of the concentric booster for Taiwan Photon Source (TPS) has been well in progress. The circumference is 496.8 m. It consists of modified FODO cells with defocusing quadrupole and sextupole fields built in bending magnets, and combined function focusing quadrupoles with imbedded focusing sextupole. The emittance is about 10 nm-rad at 3 GeV. Several modifications on the structure were made to improve the beam dynamics behaviors. Good dynamic aperture and nonlinear behavior as well as good tunability are shown. The efficient closed orbit correction scheme is presented. The repetition rate is 3 Hz, and the eddy current effect is also discussed.
BNL, Upton, Long Island, New York
CERN, Geneva
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the article we review the nonlinear beam dynamics from nonlinear magnetic fields in the Relativistic Heavy Ion Collider. The nonlinear magnetic fields include the magnetic field errors in the interaction regions, chromatic sextupoles, and sextupole component from arc dipoles. Their effects on the beam dynamics and long-term dynamic apertures are evaluated. The online measurement and correction methods for the IR nonlinear errors, nonlinear chromaticity, and horizontal third order resonance are reviewed. The overall strategy for the nonlinear effect correction in the RHIC is discussed.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In preparation for the RHIC polarized proton run 2009, simulations were carried out to evaluate the million turn dynamic apertures for different beta*s at the proposed beam energies of 100 GeV and 250 GeV. One goal of this study is to find out the best beta* for this run. We also evaluated the effects of the second order chromaticity correction. The second order chromaticties can be corrected with the MAD8 Harmon module or by correcting the horizontal and vertical half-integer resonance driving terms.
Fermilab, Batavia
Abstract The compensation of long-range beam-beam interactions with current carrying wires in the Large Hadron Collider (LHC) is studied by multi-particle tracking. In the simulations, we include the effect of long-range collisions together with the nonlinearities of IR triplets, sextupoles, and head-on collisions. The model includes the wires placed at the locations reserved for them in the LHC rings. We estimate the optimal parameters of a wire for compensating the parasitic beam-beam force by long-term simulations of beam lifetime.
Fermilab, Batavia
A beam-beam simulation code (BBSIMC) has been developed to study the interaction between counter moving beams in colliders and its compensation through a low energy electron beam. This electron beam is expected to improve intensity lifetime and luminosity of the colliding beams by reducing the betatron tune shift and spread from the head-on collisions. In this paper we discuss the results of beam simulations with the electron lens in the Relativistic Heavy Ion Collider (RHIC). We study the effects of the electron beam profile and strength on the betatron tunes, dynamic aperture, frequency diffusion and beam lifetime.
KEK, Ibaraki
Lattice design for SuperKEKB is based on the present KEKB lattice. The unit-cell structure of KEKB has a wide range of flexibility, therefore main beam-optical parameters can be adjusted without changing the arcs. The interaction region (IR) and the other straight sections are changed to squeeze the vertical beta function to 3 mm at IP, keeping sufficient dynamic apertures. Recent progress such as a new design of IR with superconducting quadrupole magnets at 1.9 K, traveling focus scheme by using crab cavities, local chromaticity correction for the high energy ring, is presented.
SLAC, Menlo Park, California
INFN/LNF, Frascati (Roma)
BINP SB RAS, Novosibirsk
The proposed SuperB factory will provide longitudinal polarized electrons to the experiment. Vertically polarized electrons will be injected into the High Energy Ring; the vertical spin orientation will be locally rotated into the longitudinal direction before the interaction point and back afterwards to avoid spin depolarization. The spin rotators can be designed using compensated solenoids–-as proposed by Zholents and Litvinenko–-to rotate the spin into the horizontal plane, followed by dipoles for horizontal spin rotation into the longitudinal direction. Such spin rotators have been matched into the existing lattice and combined with the crab-waist IR. Several ways of achieving this are explored, that differ in the degree of spin matching achieved and the overall geometry of the interaction region. The spin rotation can also be achieved by a series of dipole magnets only, which present a different optical matching problem. We will compare the different scenarios leading up to the adopted solution.
Diamond, Oxfordshire
The study of nonlinear effects in storage rings requires massively parallel particle tracking over a range of initial conditions. Stream processing architectures trade cache size for greatly increased floating point throughput in the case of regular memory access patterns. The symplectic integrator of Tracy-II* has been implemented in CUDA** on the nVidia stream processor and used to calculate dynamic apertures and frequency maps for the Diamond low-alpha lattice. To facilitate integration with existing workflows the the lattice description of Accelerator Toolbox*** is re-used. The new code is demonstrated to achieve a two orders of magnitude increase in tracking speed over a single CPU core and benchmarks of the performance and accuracy against other codes are presented.
*J. Bengtsson, Tracy-2 User's Manual, Feb 1997.
**NVIDIA, NVIDIA_CUDA_Programming_Guide_1.1.pdf
***A. Terebilo - ACCELERATOR MODELING WITH MATLAB ACCELERATOR TOOLBOX, PAC 2001
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The ALBA booster is a 100 MeV-3 GeV ramping synchrotron, with large circumference of 249.6 m and low emittance of 9nm*rad, cycling at 3 Hz. The lattice consists of a 4-fold symmetric modified FODO lattice with defocusing gradient dipoles. Magnetic measurements on all magnets have been performed: the studies and lattice settings to recover the design optics preserving good machine performances, such as the lattice flexibility, the low beta functions and large dynamic aperture at high chromaticities, are presented.
Imperial College of Science and Technology, Department of Physics, London
The Race Track design for the Decay Ring of a Neutrino Factory is studied with the MAD-X code. Optimisation of the working point, study of resonances and of dynamic aperture for several off-momentum cases are presented. An introduction to the problem of beam losses is given.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Optimization of dynamic and momentum aperture is one of the most challenging problems in storage ring design. For storage-ring-based x-ray sources, large dynamic aperture is sought primarily to obtain high injection efficiency, which is important in efficient operation but also in protecting components from radiation damage. X-ray sources require large momentum aperture in order to achieve workable Touschek lifetimes with low emittance beams. The most widely applied method of optimizing these apertures is to minimize the driving terms of various resonances. This approach is highly successful, but since it is based on perturbation theory, it is not guaranteed to give the best result. In addition, the user must somewhat arbitrarily assign weights to the various terms. We have developed several more direct methods of optimizing dynamic and momentum aperture. These have been successfully applied to operational and design problems related to the Advanced Photon Source and possible upgrades.
BNL, Upton, Long Island, New York
Successful operation of NSLS-II requires sufficient dynamic aperture for injection, as well as momentum aperture for Touschek lifetime. We explore the dependence of momentum and dynamic aperture on higher-order multipole field errors in the quadrupoles and sextupoles. We add random and systematic multipole errors to the quadrupoles and sextupoles and compute the effect on dynamic aperture. We find that the strongest effect is at negative momentum, due to larger closed orbit excursions. Adding all the errors based on the NSLS-II specifications, we find adequate dynamic and momentum aperture.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The Spanish synchrotron light source ALBA is in the process of installation, with the large majority of components already manufactured and delivered. Among them, the magnets of the storage ring. As part of the acceptance process of the magnets, a campaign to measure the quality of them (magnetic length, effective bending and focusing, high order multipolar components) has been performed in-house and in the manufacturer. The results of this measures have been applied to the model of the storage ring, analyzing the effects in the performance (lifetime, dynamic aperture, orbit, etc). The results of the study confirm the quality of the magnet's design and manufacturing as well as the performance of the lattice.
BINP SB RAS, Novosibirsk
INFN/LNF, Frascati (Roma)
A project of the SuperB Factory in Italy with the crab-waist collision scheme and extremely large luminosity addresses new challenges to the nonlinear beam dynamics study. Among these challenges are: low emittance lattice requiring strong sextupoles for chromatic correction, sub-mm vertical betatron function at the IP, crab sextupoles placed at both sides from the IP, etc. In this report we describe the results of the DA limiting sources analysis and optimization of the arrangement of the IR and Crab sextupoles and octupoles for the Low Energy Ring (LER).
Tech-X, Boulder, Colorado
Fermilab, Batavia
Funding: This work was supported by the US DOE Office of Science, Office of Nuclear Physics, under Grant No. DE-FG02-08ER85183
A new set of tools for BBSIM has recently been developed to analyze the nature of the diffusion in multi-particle simulations. The diffusion subroutines are currently used to accelerate beam lifetime calculations by estimating the diffusion coefficient at various actions and integrating the diffusion equation. However it is possible that there may be regimes where anomalous diffusion dominates and normal diffusion estimates are incorrect. The tools we have developed estimate the deviation from normal diffusion and can fit the coefficients of a jump diffusion model in the event that this type of diffusion dominates.
GSI, Darmstadt
The main purpose of the Recuperated Experimental Storage Ring (RESR) in the FAIR project is the accumulation of antiprotons coming from the Collector Ring (CR), where they are stochastically pre-cooled. The accumulation scheme in the RESR foresees longitudinal stacking in combination with stochastic cooling. The stochastic cooling process strongly depends on the slip factor η of the ring. Presently, the RESR is designed to operate with small slip factor of 0.03. In order to increase the flexibility for optimized stochastic cooling a new alternative ion-optical mode with higher slip factor of 0.11 has been calculated in such a way, that the RESR can be operated with a fixed magnetic structure in both modes. The influence of the high-order chromaticity on the particle motion has been investigated and a chromaticity correction scheme is applied. The variation of the transition energy over the momentum acceptance was examined and the possibility of its correction is described.