INFN/LNF, Frascati (Roma)
SLAC, Menlo Park, California
CERN, Geneva
BINP SB RAS, Novosibirsk
KEK, Ibaraki
University of Pisa and INFN, Pisa
The SuperB project aims at the construction of an asymmetric (4x7 GeV), very high luminosity, B-Factory on the Roma II (Italy) University campus. The luminosity goal of 1036 cm-2 s-1 can be reached with a new collision scheme with large Piwinski angle and the use of “crab” sextupoles. A crab-waist IR has been successfully tested at the DAPHNE Phi-Factory at LNF-Frascati (Italy) in 2008. The crab waist together with very low beta* will allow for operation with relatively low beam currents and reasonable bunch length, comparable to those of PEP-II and KEKB. In the High Energy Ring, two spin rotators permit bringing longitudinally polarized beams into collision at the IP. The lattice has been designed with a very low intrinsic emittance and is quite compact, less than 2 km long. The tight focusing requires a sophisticated Interaction Region with quadrupoles very close to the IP. A Conceptual Design Report was published in March 2007, and beam dynamics and collective effects R&D studies are in progress in order to publish a Technical Design Report by the end of 2010. A status of the design and simulations is presented in this paper.
BNL, Upton, Long Island, New York
Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886.
The NSLS-II is an ultra-bright synchrotron light source based upon a storage ring with a 30-cell double-bend-achromat lattice with damping wigglers used to lower the emittance below 1 nm. In this talk we discuss the accelerator physics challenges for the design including: optimization of dynamic aperture; estimation of Touschek lifetime; achievement of required orbit stability; and analysis of ring impedance and collective effects.
INFN/LNF, Frascati (Roma)
LAL, Orsay
CERN, Geneva
roma3, Rome
Rome University La Sapienza, Roma
BINP SB RAS, Novosibirsk
KEK, Ibaraki
BINP, Novosibirsk
SLAC, Menlo Park, California
INFN-Roma, Roma
In 2007 DAΦNE was upgraded to operate in a regime of large Piwinski angle, with a novel IR optics, reduced vertical beta at the interaction point, and additional sextupoles providing for crab waist collisions. The specific luminosity was boosted by more than a factor of four, and the peak luminosity was more than doubled with respect to the maximum value obtained with the original collider configuration. The DAΦNE commissioning as well as the first experience with large Piwinski angle and crab waist collisions scheme will be reported.
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.
A steering magnet is not a major component in a beam line, however it is usually needed in any real set up. Also it is hard to estimate the required field strength before the beam line construction, since the strength needed is determined by misalignnment errors of other devises. Sometimes it is difficult to find enough space to install steering magnets because of other constraints on the length of the beamline. We compare two extreme designs of steering magnets. The first one is very thin steering magnet design which occupies only 6 mm in length and can be additionally installed as needed. The other is realized by applying extra coil windings to a quadrupole magnet and does not consume any length. We will present both designs in details and will discuss pros and cons.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
Feasibility studies for two families of corrector magnets for NSLS-II are presented. The first family of magnets are generalizations of figure eight quadrupoles using rotationally symmetric breaks in the return yoke to fit in available space. Properties specific to figure eight magnet are identified. The second type of magnet is a combined sextupole/dipole trim.
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
Funding: US DOE Office of Basic Energy Sciences
NSLS-II is a new state-of-the-art medium energy synchrotron light source designed to deliver world leading brightness and flux with top-off operation for constant output. Design and engineering of NSLS-II began in 2005 and the beginning of construction and operations are expected to start in 2009 and 2015, respectively. The energy of the machine is 3Gev and the circumference 792 m. The chosen lattice requires tight on magnetic field tolerances for the ring magnets. These magnets have been designed with 3D Opera software. The required multipole field quality and alignment preclude the use of multifunctional sextupoles, leading to discrete corrector magnets in the storage ring. The corrector magnets are multifunctional and will provide horizontal and vertical steering as well as skew quadrupole. This paper describes the dipoles, quadrupoles, sextupoles, and corrector magnets design and prototyping status of the NSLS-II.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
The Sextupole magnets for the National Synchrotron Light Source (NSLS-II) have stringent performance requirements. These magnets have a faceted pole profile departing from the classic shape due to constraint imposed by the vacuum tube. Three different geometric features were used as parameters to minimize unallowed harmonics. Prototypes were measured and have confirmed the good field quality.
BINP SB RAS, Novosibirsk
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
BINP has manufactured and measured 243 multipoles of 9 types for the ALBA storage ring. The magnets had severe requirements on the manufacturing tolerances and the alignment of their magnetic axes. The quadrupole magnets are made of 1mm laminated yokes with the bore diameter of 61mm. The sextupole magnets are made of 0.5mm laminated yokes with the bore diameter of 76mm. Rotating coils and Hall probes have been used for the magnetic measurements. The features of manufacturing and magnetic measurements are presented in this paper.
Fermilab, Batavia
Funding: Work supported by the U.S. Department of Energy
The fabrication of the multi-element corrector magnets for the Fermilab Booster synchrotron has just been completed. These water-cooled packages include six different corrector types - normal and skews oriented dipole, quadrupole and sextupole elements. They will provide full orbit control, tune and chromaticity of the beam over the whole range of Booster energies, from 0.4 GeV to 8 GeV. During production, a set of quality assurance measurements were performed, including special thermal tests. This paper summarizes the results from these measurements as well as discussing some specific steps of the magnet fabrication process.
FZJ, Jülich
iThemba LABS, Somerset West
Funding: Work supported by BMBF and NRF, Project code SUA 06/003
Forschungszentrum Jülich has taken the leadership of a consortium responsible for the design, installation and commissioning of the High-Energy Storage Ring (HESR) for antiprotons as part of the FAIR project at GSI in Darmstadt, Germany. Since a normal-conducting design of the ring has now been favored over the previously envisioned superconducting option, new calculations have been performed in order to assess the magnetic field characteristics of the normal-conducting dipole, quadrupole, and sextupole magnets of the HESR. This paper presents the physical features of the magnets and the results of the 3D calculations with emphasis on the various multipole contributions at the ends of the magnets.
NSRRC, Hsinchu
Abstract A 3-GeV electron-storage ring with tiny emittance has been designed for the Taiwan Photon Source (TPS) that will provide one of the world's brightest synchrotron x-ray sources. Sextupole magnets for the booster ring (BR) serve to correct the chromaticity of the beam particles. As an AC power supply is generally used in a booster ring to raise beam particles to a required energy, a power supply at 3 Hz AC is used to charge the sextupole magnet, which would induce eddy currents in the vacuum chamber resulting in a magnetic multipole field. As an aspect of the magnet design, decreasing the effect of an eddy current on the homogeneity of the magnetic field, the geometry and material of the chamber must be considered. We demonstrate the effects of an eddy current on the homogeneity of a magnetic field for a vacuum chamber of various types, and we discuss the magnetic circuit and the conductor design of the booster-ring sextupole. Analysis of the multipole field and eddy-current loss were included to assure the accuracy of the magnetic circuit design.
NSRRC, Hsinchu
The accelerator lattice magnets of the Taiwan Photon Source (TPS) with energy 3 GeV have been designed for the storage and booster ring. The magnetic computation codes of TOSCA and RADIA software packages were used to design the magnet circuits of the accelerator magnets. Meanwhile, the design of a magnet circuit must take into account both the requirements of accelerator physics and practical engineering constraints. The criterion of magnet design is to keep a rise of coil temperature within 10o C and a safety margin greater than 15 %. We apply pole edge shims and end magnet chamfers to enhance the field homogeneity and to decrease multipole components, respectively. The edge shim involves a smaller magnet dimension but maintains the same quality of the field. Use of an end magnet chamfer avoids field saturation. The mechanical engineering design of the storage ring magnets has been completed and the booster ring magnets have started to be designed. The 3D Solidworks package was used to draw and design the mechanical engineering. The prototype magnets of the storage ring have been contracted out to the local company in Taiwan and will be finished before the end of 2009.
NSRRC, Hsinchu
Lots of multipole magnets will be fabricated for the accelerator lattice magnets of Taiwan Photon Source (TPS) that include the storage ring magnets, booster ring magnets, and the transfer line magnets. Therefore, several precise rotating-coil measurement systems (RCS) with high speed measurement are developed to characterize the magnetic field of quadrupole (QM) and sextupole (SM) magnets. Printed circuit coil including normal-coil and bucking-coil, are applied to measure the absolute and relative values of multipole components, respectively. Normal-coils with three turns (single-layer-coil) has been previously discussed and found to have good reproducibility. Moreover, a 12-turn multi-layer-coil has been designed to characterize the booster ring multipole magnets of TPS. This study, compares the compensatory characteristics of two bucking-coils with 75/150 turns and 150/300 turns with those of normal-coil. A continuously-winding-method for bucking-coil is presented in the paper. A precision testing bench was used to test the performance of this system. This work describes the measurement system design and fabrication, and discusses the system precision and accuracy.
NSRRC, Hsinchu
Bending magnets, quadrupole magnets, and sextupole magnets are the most crucial magnetic elements in the synchrotron accelerator facility or high energy accelerator collider ring. Generally, separate bending magnets, quadrupoles or sextupoles magnets are utilized to perform separate functions. However, in the lattice design of accelerator ring or a compact ring in limited space, a single multifunction magnet is used to reduce the number of magnets and ensure that the entire device fits into the available space. This work presents an approach for designing the pole profiles of a combined-function bending magnet of the dipole, quadrupole, and sextupole components. The pole profile of a combined quadrupole magnet with gradient field and sextupole field components is also discussed.
PAL, Pohang, Kyungbuk
Funding: Supported by the MOEST of Korea and by POSCO
Pohang Accelerator Laboratory (PAL) is planning to upgrade the Pohang Light Source (PLS) which is a 3rd generation light source operating since 1995. The key features of the upgrade are, decrease of the beam emittance to 5.6 nm, increasing the beam energy to 3.0 GeV, additional shorter straight sections for more insertion devices. Because the PLSII should use practically same circumference preserving the shielding wall structure of the existing PLS, the lattice space is squeezed to the limit to secure the additional space for the insertion devices. This requirements forces heavy use of the combined function magnet. All dipoles are replaced to gradient magnet, and all sextupoles have horizontal corrector winding, vertical corrector winding, skew quadrupole windings. In this report, the design features and engineering efforts for the PLSII magnet systems are reported.
PAL, Pohang, Kyungbuk
Funding: * Work supported by Korean Ministry of Education Science and Technology
The magnets for a medical synchrotron were designed. The synchrotron is for cancer therapy with proton and carbon-iron beams. The magnets for the injection include a septum magnet and an electrostatic septum magnet. And the magnets for the extraction include a resonance sextupole magnet, an electrostatic septum magnet, a thin septum magnet, and a thick septum magnet. The design achieved good field uniformity and acceptable leakage field level. We used 3D code for the electromagnetic simulation and the optimization of magnetic structures. In this paper, the basic design process for the injection and extraction magnets will be presented.
JLAB, Newport News, Virginia
Funding: Work supported by the US DOE Contract #DE-AC05-060R23177 and the Commonwealth of Virginia.
The characteristics of the system of “SF” Sextupoles for the infrared Free Electron Laser Upgrade at the Thomas Jefferson National Accelerator Facility (JLab) are described. These eleven sextupoles possess a large field integral (2.15 T/m) with ± 0.01% field quality over a 150 mm width within a very short effective length (150 mm pole length) and have field clamps for fast field roll-off. The field integrals reproduce extremely well with good absolute resolution (± 0.1%). The simple, two-dimensional shape pole tips (directly from the original 3-D RADIA magnetic model) of these “all ends” magnets include the correction for end fields. Magnetic measurements are compared to the model. The system’s hysteresis protocol and power supplies were also used for the measurement process to enhance reproducibility in service, a recent initiative at JLab. The intricacies of magnetic measurement using the JLab field probe based Stepper Stand are described. The challenges of developing the in-house design power supplies for these magnets, based on use of a low quality supply brought to 0.001% current regulation by a CAN-Bus control are described.
USTC/NSRL, Hefei, Anhui
HALS(Hefei Advanced Light Source) is the electron storage ring of ultra-low emittance in process of design. Under this design, the quadrupole magnet with sextupole component must be mounted on which the βη is much bigger, to use enough the effect of compersation chromaticity of sextupole magnet field and to use sparingly the space in the same time . So the combined quadrupole and sextupole magnet must be designed, and have more strong sextupole component and restrain the production of high harmonic field. In this paper, the chocie of design scheme is discussed, and the calculation of combined quadrupole and sextupole mangnet design is given.
BNL, Upton, Long Island, New York
IN2P3-LAPP, Annecy-le-Vieux
OXFORDphysics, Oxford, Oxon
CERN, Geneva
SLAC, Menlo Park, California
KEK, Ibaraki
Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886.
The Accelerator Test Facility (ATF2) at KEK is a scaled down version of the final focus design proposed for the future linear colliders (LC) and aims to experimentally verify the final focus (FF) technology needed to obtain very small, stable beam spots at a LC interaction point. Initially the ATF2 FF is made using conventional (warm) quadrupole and sextupole magnets; however, we propose to upgrade the FF by replacing some of the conventional magnets with new superconducting magnets constructed with the same technology as those of the International Linear Collider baseline FF magnets*. With the superconducting magnet upgrade we can look to achieve smaller interaction point beta-functions and to study superconducting magnet vibration stability in an accelerator environment. Therefore for the ATF2 R&D magnet we endeavor to incorporate cryostat design features that facilitate monitoring of the cold mass movement via interferometric techniques. The design status of the ATF2 superconducting upgrade magnets is reported in this paper.
*International Linear Collider Reference Design Report, ILC-REPORT-2007-001, August 2007.
LBNL, Berkeley, California
KEK, Ibaraki
Funding: U.S. Department of Energy
The Superconducting Magnet Program at Lawrence Berkeley National Laboratory has designed and tested HD2, a 1 m long Nb3Sn accelerator-type dipole with a 42 mm clear bore. HD2 is based on a simple block-type coil geometry with flared ends, and represents a step towards the development of cost-effective accelerator quality magnets operating in the range of 13-15 T. The design was optimized to minimize geometric harmonics and to address iron saturation and conductor magnetization effects. Field quality was measured during recent cold tests. The measured harmonics are presented and compared to the design values.
LBNL, Berkeley, California
Third generation Electron Cyclotron Resonance (ECR) ion sources operate at rf frequencies between 20 and 30 GHz and employ NbTi superconducting magnets with a conductor peak field of 6-7 T. A significant gain in performance can be achieved by replacing NbTi with Nb3Sn, allowing solenoids and sextupole coils to reach a field of 15 T in the windings. In this paper we describe the design of a Nb3Sn superconducting magnet for a fourth generation ECR source operating at a rf frequency of 56 GHz. The magnet design features a configuration with an internal sextupole magnet surrounded by three solenoids. A finite element magnetic model has been used to investigate conductor peak fields and the operational margins. Results of the numerical analysis are presented and discussed.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract number DE-AC02-06CH11357.
Investigation into a circular polarizing quasi-periodic undulator is presented here. Electromagnets are used to generate the vertical field. Permanent magnets are used to generate the horizontal field. Calculated maximum effective vertical and horizontal magnetic fields on the undulator axis higher than 8.5 kGauss are achieved at a 10.5-mm gap for a 9-cm-period undulator. Fields of this magnitude are difficult to achieve in purely electromagnetic devices. Switching the sign of the current for the vertical field electromagnets allows for right- or left-handed circular polarization. A laminated core can be introduced to allow for fast helicity switching in order to utilize lock-in detection techniques. Quasi-periodicity can be introduced in the vertical electromagnet field by reducing the current at the quasi-periodic poles and can be turned on, off, or somewhere in between. Quasi-periodicity can be introduced in the horizontal permanent magnet field by inserting weakened magnets at the quasi-periodic poles. Since it is built into the magnet structure, this quasi-periodicity cannot be turned off.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
This paper will describe the requirements, the design and the prototype test results of the magnets for the new synchrotron radiation source NSLS-II now under construction at BNL. Several innovations have been incorporated in the design, in manufacturing and in the alignment procedures of the magnets. Prototypes of these magnets have been built in industry. A dipole design has been developed with a maximized magnetic length which is longer than the mechanical length. The quadrupole and sextupole magnets of NSLS-II must be aligned and positioned to better than 30 microns, a level never achieved before in such accelerators. The paper will present a brief status of the progress made in the techniques developed to measure and achieve these demanding requirements. Another concern has been the distortion of field quality due to the small (150 mm) axial spacing between the iron-yoke of two adjacent magnets. Calculations (in 3-D) and the result of systematic measurements of the field quality in the presence of other magnets and other machine components in close proximity will be presented.
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
ANL, Argonne
Funding: This work was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source is filled for five weeks per year in a special bunch (hybrid) pattern of one large 16-mA (74-nC) bunch in a gap of 3 microseconds, and the remaining 86 mA in 8 trains of 7 consecutive bunches, forming a 500-microsecond-long bunch train. We are developing variations of this bunch pattern, which might have 3 large bunches equally spaced in the 3-microsecond gap in a 4-mA, 16-mA, and 8-mA distribution. The 500-microsecond-long bunch train could be changed to 2 or 3 bunch trains of 7 bunches. We report on the difficulties in bringing these into future operations: impedance-driven injection losses, sextupoles in injection section, lifetime and topup injection limit, and beam diagnostics responses to the patterns.
BNL, Upton, Long Island, New York
The NSLS II is a state of the art 3 GeV synchrotron light source being developed at BNL. The injection system will consist of a 200 MeV linac and a 3GeVbooster synchrotron. The transport lines between the linac and booster (LtB) and the booster and storage ring (BtS) must satify a number of requirements. In addition to transporting the beam while mantaining the beam emittance, these lines must allow for commissioning, provide appropriate diagnostics, allow for the appropriate safety devices and and in the case of the BtS line, provide for a stable beam for top off injection. Appropriate diagnostics are also necessary in the linac and booster to complement the measurements in the transfer lines. In this paper we discuss the design of the transfer lines for the NSLSII along with the incorporated diagnostics and safety systems. Necessary diagnostics in the linac and booster are also discussed.
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.
BNL, Upton, Long Island, New York
Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886
The NSLS-II light source is a proposed 3 GeV storage ring, with the potential for ultra-low emittance*. The lattice design uses a 30 cell DBA structure with a periodicity of 15, for alternating long and short straight sections. All cells are tuned achromatic to maximize the emittance reduction achieved as damping wigglers are added to the ring. Recent optimization of the lattice consisted of increasing the number of possible hard X-ray beam ports using three pole wigglers, reducing the number of magnets (quadrupoles and sextupoles) and shifting the magnets to allow easier extraction of the photon beams. The impact of the reduction of magnets on the lattice flexibility will be presented in terms of the tuning range possible for the lattice parameters: tune, emittance, and chromaticity, beta function matching to user insertion devices (IDs) and for compensating for ID induced distortions to these parameters. This flexibility is important for optimizing the lattice linear and nonlinear properties, the dynamic aperture, and its impact on beam lifetime, as well as matching the user source requirements and for value engineering of magnets and power supplies.
*Work presented on behalf of the NSLS-II Design Team, CDR(2006), CD2(2007) and CD3(2008).
BNL, Upton, Long Island, New York
BESSY GmbH, Berlin
The NSLS-II is a state of the art 3 GeV synchrotron light source that is being developed at BNL. The 9.3 meter long injection straight section of NSLS-II storage ring currently fits a conventional injection set-up that consists of four kickers producing a closed bump together with a DC septum and a pulsed septum. In this paper we analyze alternative options based on: a) injection via a pulsed sextupole and b) injection with a Lambertson septum. We discuss dynamics of the injected and stored beams and, consequently, magnet specifications and tolerances. In conclusion we summarize advantages and drawbacks of each injection scheme.
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.
LSU/CAMD, Baton Rouge, Louisiana
To control the emittance coupling in the CAMD Light Source, new power supplies have been constructed which adjust the currents in the individual coils of the normal lattice sextupoles, thereby creating skew quadrupole fields. The new power supplies add or subtract current through the pre-energized coils. Performance contributing factors include a summing network with a temperature coefficient less than 1ppm/°C, a water cooled resistive shunt, and linear optical signal isolation. High density & modularity control boards and water cooled power cards are mounted as pull-out units in a 19” rack. Active limiters and fault indicators can provide reliability and portability to higher power designs. The use of these skew quadrupoles in controlling and minimizing the emittance coupling is presented.
ISSP/SRL, Chiba
JAEA/ERL, Ibaraki
KEK, Ibaraki
A compact ERL (energy recovery linac) is planned in Japan in order to demonstrate excellent ERL performances and to test key components such as low-emittance photocathode gun and superconducting RF cavity. We studied and optimized the compact ERL optics (except the injector part) to generate a subpico-second bunch in bunch compression mode and to preserve the beam emittance in normal and low-emittance mode. As a result, we could obtain a very short bunch of about 50 fs with a charge of 77 pC in bunch compression mode and almost keep the normalized emittance of 0.1 mm mrad with a charge of 7.7 pC in low-emittance mode. We also designed it to achieve efficient energy recovery at the superconducting RF cavities and to transport the beam to the dump section without serious loss. The design study of the compact ERL optics was carried out with the simulation code Elegant, including CSR(coherent synchrotron radiation) effects. In this paper, we will present the results of the beam optics study for the compact ERL.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS storage ring uses DC/DC converters to power the magnets. High resolution for current regulation is desired for future improvement. It is calculated that at least 20- to 21-bit digital pulse width modulation (DPWM) is required in the proposed digital control system. This paper proposes a digital control system that adopts a new DPWM topology to achieve 21-bit DPWM without gigahertz system clock. The proposed topology uses a combination of a field-programmable gate array (FPGA) and a serializer chip TLK2541 from TI. The FPGA calculates the desired PWM signals and sends them to the TLK2541 chip. Then, the TLK2541 generates corresponding high-resolution DPWM pulses. An FPGA development board has been used to develop a prototype system to verify the proposed DPWM generation topology. This paper discusses the circuit topology and the experiment results.
CERN, Geneva
ETH, Zürich
UNAM, México, D.F.
For the proposed PS2 accelerator several extraction systems are needed, including a slow third-integer resonant extraction. The requirements are presented together with the conceptual considerations for the sextupole locations and strengths, the separatrices at the extraction elements and the aperture implications for the overall machine. Calculations of the phase space separatrices have been computed with a new code for the physics of slow resonant extraction, which is briefly reviewed. Implications for the extraction equipment design and for the injection-extraction straight section optics are discussed.
GSI, Darmstadt
The FAIR heavy ion synchrotrons SIS100/300 will provide heavy ion and proton beams with variable time structure. Fast extraction of compressed single bunches from SIS100, fast beam transfer between SIS100 and SIS300 and slow extraction from SIS100 and SIS300 will be provided. High average beam intensities and the generation of an uninterrupted linac-like beam are enabled by combining both heavy ion synchrotrons in different operation modes (fast acceleration and stretcher operation). In order to reduce beam loss at slow extraction of intense heavy ion beams and to minimize the beam load in subsequent accelerator structures, dedicated ion optical settings of the basic lattice functions and higher order corrections will be applied. However, the tight geometrical constraints in the rather short straight sections and the need to extract from both synchrotrons, fast and slow, at the same position and in parallel to the beam transport system, require operation parameters of the extraction devices close to the limits of technical feasibility. Higher order beam dynamics simulations and technical developments will be presented.
ISSP/SRL, Chiba
KEK, Ibaraki
We successfully demonstrated a new beam injection method using a single pulsed sextupole magnet (PSM). The PSM has a parabolic-shaped magnetic field, which is expected to provide an effective kick to the injected beam without little effects on the stored beam. We installed the PSM injection system at the Photon Factory storage ring (PF-ring) and succeeded in injecting the beam into PF-ring and storing the current up to 450 mA. This is the first demonstration of the PSM beam injection in electron storage rings. We also tested top-up injection and confirmed that dipole oscillation of the stored beam was sufficiently reduced compared with that generated by the conventional injection system. In this conference, we will present the experimental results and the advantages of the PSM beam injection.
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.
The response matrix fit is routinely used at APS for linear optics correction. The high accuracy of the method enables us to measure the variation of betatron phase advance around the ring with rf frequency. This variation can be used to calculate local chromaticity. Such measurements were first performed at the APS at the moment when a sextupole was mistakenly connected with the wrong polarity. Local chromaticity calculations clearly pointed to the location of the sextupole error. Results and details of the measurements are reported and discussed.
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.
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.
NSRRC, Hsinchu
Quadruple Bend Achromat (QBA) low emittance lattice of 3GeV Taiwan Photon Source (TPS) allows us to consider three configurations for location of a pair of superconducting transverse RF deflecting cavities for generation ultra short X-ray pulses. The available arrangements for location of cavities in a super-period of TPS are investigated. We find that use of such deflecting cavities in the middle of two QBA lattices in a super-period of TPS provides better conditions for emittance of electron beam.
NSRRC, Hsinchu
A 3 GeV synchrotron light source is planned to be built at the existing site of NSRRC campus. The project is called the Taiwan Photon Source (TPS). It will provide x-ray photon beam with brilliance several orders higher than the one generated by the existing 1.5 GeV synchrotron. The design issues of accelerator lattice for the 3 GeV storage ring and booster injector will be presented. These issues cover the properties of linear and nonlinear beam dynamics, the optimization of dynamic aperture and momentum acceptance, collective beam instabilities and lifetime issues, the effects caused by various error sources and technical measures to suppress these error effects, etc.
PSI, Villigen
MAX-lab, Lund
Utilizing a large number of non-dispersive (24) and dispersive (6) skew quadrupoles the betatron coupling and the vertical spurious dispersion can be simultaneously reduced to extremely small values. As a result the achieved vertical emittance begins to approach its ultimate limit, set by the fundamental quantum nature of synchrotron radiation, which in the SLS case is ~0.55 pm.rad. At the same time emittance measurements based on the fitting of a diffraction limited vertical photon beam from a dipole have been pushed to the limit in order to verify this ultra-low vertical emittance.
PSI, Villigen
Recently the energy acceptance and Touschek lifetime of the storage ring of the Swiss Light Source (SLS) could be successfully set to values in agreement with simulations for an ideal lattice. This was finally achieved through control of linear coupling and symmetrization of the sextupole pattern. 36 small corrector magnets were installed for this purpose as additional windings on the ring sextupoles: 30 skew quadrupoles (24 at zero and 6 at maximum dispersion) and 6 auxiliary sextupoles. Base for the success of these measures were previous corrections of dipolar and quadrupolar errors, which we will summarize briefly.
SAGA, Tosu
Kyoto IAE, Kyoto
The procedure of accelerator modeling using orbit response matrix fitting is well known and widely adopted at many light sources, we also examined the model fitting to diagnose optics and to restore the periodicity of the storage ring optics. In the modeling procedure we used the tracking code TRACY2, because it can calculate the orbit response matrix including energy offset caused by the dipole kick. The multi-parameter fitting was carried out by using SVD algorism implemented in the Labview mathematical package. In the fitting procedure, we fixed a steering magnet field to the value obtained from the orbit measurement using screen monitor to avoid explicit solution between the steering strengths and the BPM gains. By adopting the orbit response matrix fitting, it was found that the quadrupole strength is about 3-5% larger than the calculated value obtained from magnetic measurement data and output current of the power supply. In the conference, we will report on the result of the modeling procedure and its application to the optics correction.
RIKEN/SPring-8, Hyogo
The compact XFEL facility under construction in the SPring-8 campus aims at generation of SASE based XFEL at the wavelength of ~0.1 nm in 2010. Toward the smooth completion of the beam commissioning and achieving the reliable SASE XFEL operation, it is critically important to suppress the dark current upstream of the accelerator as much as possible. We thus investigated a removal scheme of the spatially diverged and energy deviated electrons forming the dark current by using sextupole magnets, which are installed over the C-band accelerating structures. The beam simulation showed that the combination of the distributed sextupole magnets with a small chicane, which locates in the adequate middle of the C-band accelerating structures, could efficiently remove the dark current emitted from the C-band acceleration structures. Here, we present the simulation results and the dark current suppression scheme designed for the compact XFEL facility at SPring-8.
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.
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.
There is significant interest in RHIC heavy ion collisions at center of mass energies of 5-50 GeV/u, motivated by a search for the QCD phase transition critical point. The low end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy of 19.6 GeV/u. There are several operational challenges in the low-energy regime, including harmonic number changes, longitudinal acceptance, magnet field quality, lattice control, and luminosity monitoring. We report on the results of beam tests with protons and gold in 2007–9, including first RHIC operations at √{(sNN)=9.2} GeV and low-energy nonlinear field corrections at √{(sNN)=5} GeV.
CERN, Geneva
BNL, Upton, Long Island, New York
KEK, Ibaraki
For several years optics measurement and correction algorithms have been developed for the LHC. During 2008 these algorithms have been directly tested in the SPS and RHIC. The experimental results proving the readiness of the applications are presented.
CERN, Geneva
BNL, Upton, Long Island, New York
In early LHC commissioning, linear and "higher-order" polarity checks were performed for one octant per beam, by launching suitable free betatron oscillations and then inverting a magnet-circuit polarity or strength. Circuits tested included trim quadrupoles, skew quadrupoles, lattice sextupoles, sextupole spool-pieces, Landau octupoles, and skew sextupoles. A nonzero momentum offset was introduced to enhance the measurement quality. The low-intensity single-pass measurements proved sufficiently sensitive to verify the polarity and the amplitude of (almost) all circuits under investigation, as well as the alignment of individual trim quadrupoles. A systematic polarity inversion detected by this measurement helped to pin down the origin of observed dispersion errors. Later, the periodic "ring dispersion" was reconstructed from the full first-turn trajectory of an injected off-momentum beam, by removing, at each location, the large incoming dispersion mismatch, forward-propagated via the optics model. Various combinations of inverted trim quadrupoles were considered in this model until reaching a good agreement of reconstructed dispersion and prediction.
KEK, Ibaraki
Crab cavities were installed at KEKB at the beginning of 2007. The beam operation with the crab cavities is in progress. In this paper, machine performance with crab crossing is described focusing on a specific luminosity and a beam lifetime issue related to the dynamic beam-beam effects.
BINP SB RAS, Novosibirsk
INFN/LNF, Frascati (Roma)
KEK, Ibaraki
A novel scheme of crab waist collisions has been successfully tested at the electron-positron collider DAΦNE, Italian Phi-factory. In this paper we compare numerical simulations of the crab waist beam-beam interaction with obtained experimental results. For this purpose we perform weak-strong and quasi strong-strong beam-beam simulations using a realistic DAΦNE lattice model that has proven to reproduce reliably both linear and nonlinear collider optics.
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.
UMAN, Manchester
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
The Accelerator Test Facility (ATF2) at KEK aims to experimentally verify the local chromaticity correction scheme to achieve a vertical beam size of 37nm. The facility is a scaled down version of the final focus design proposed for the future linear colliders. In order to achieve this goal, high precision tuning methods are being developed. One of the methods proposed for ATF2 is a novel method known as the ‘rotation matrix’ method. Details of the development and testing of this method, including orthogonality optimisation and simulation methods, are presented.
INFN/LNF, Frascati (Roma)
CERN, Geneva
The CLIC drive beam current, produced by the 1 GHZ fully loaded Linac, will be multiplied by a factor of 24 by the frequency multiplication system, to generate the high power beam representing the CLIC power source. The frequency multiplication system is composed by one delay loop plus two combiner rings. All rings will be isochronous, will contain trajectory tuning wigglers, and all magnets will be normal conducting. The design of the rings, with special emphasis on the rf deflectors characteristics, is presented.
BNL, Upton, Long Island, New York
Fermilab, Batavia
The University of Texas at Austin, Austin, Texas
An AC dipole magnet produces a sinusoidally oscillating dipole field with frequency close to betatron frequency and excites large sustained oscillations of beam particles circulating in a synchrotron. Observation of such oscillations with beam-position-monitors allows direct measurements of a synchrotron's nonlinear parameters. This paper presents experimental studies to measure effects of sextupole and octupole fields, such as tune dependence on amplitude and resonance driving terms, performed in the Fermilab Tevatron using an AC dipole.
NSRRC, Hsinchu
Since use of such deflecting structures leads to growth in vertical amplitude and slope of electrons, non-zero momentum compaction factor, nonlinearities and coupling of the elements between the deflectors affect the tilted electrons even in perfect machine and change their amplitude and slope at second deflecting cavity. It causes the second deflector cannot cancel the first kick perfectly and leads to increase of transverse emittance. We have studied simulation and detail analyses of effects of non-zero momentum compaction factor and sextupoles between the deflecting structures, as sources of emittance degradation in TPS and evaluate how much emittance growths due to the effects. We also contrast the statuses of interior sextupoles and elucidate them.
BNL, Upton, Long Island, New York
Funding: Work performed under the auspices of the US DOE.
The existence of multipolar components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. Therefore, the statistical properties of the non-linear fields are crucial for understanding the beam behavior and for achieving the superior performance in RHIC. In an earlier work*, the field quality analysis of the RHIC interaction regions (IR) was presented. Furthermore, a procedure for developing non-linear IR models constructed from measured multipolar data of RHIC IR magnets was described. However, the field quality in the regions outside of the RHIC IR regions had not yet been addressed. In this paper, we present the statistical analysis of multipolar components in the magnetic fields of the RHIC arc regions. The emphasis is on the lower order components, especially the sextupole in the arc dipole and the 12-pole in the quadrupole magnets, since they are shown to have the strongest effects on the beam stability. Finally, the inclusion of the measured multipolar components data of RHIC arc regions and their statistical properties into tracking models is discussed.
*J. Beebe-Wang and A. Jain, “Realistic Non-linear Model and Field Quality Analysis in RHIC Interaction Regions”, proc. of PAC 2007, page 4309-4311 (2007)
KEK, Ibaraki
KEKB is a double-ring collider with a circumference of 3016 m. The two rings were built side-by-side in the TRISTAN tunnel, 11 m below ground. KEKB has been operating successfully for about 10 years, since 1999, and its peak luminosity continues to improve. During the summer shutdown of 2008, the magnet tilts were measured for the first time since installation and it was found that some magnets were rotated over time. The tunnel level marker and the magnet height were also surveyed. The south region of the tunnel is sinking, resulting in magnet level changes. The survey results will be reported in this paper.
ANL, Argonne
Funding: This work was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CHlI357.
During an operating period in which a sextupole unknowingly connected with the wrong polarity resulted in reduced beam lifetime, a list of machine physics experiments and simulations were developed to identify possible gradient errors of one or more sextupole magnets. We tried tune dependence on orbit, response matrix measurements at different momenta, sector-wise chromaticity measurements, empirical search with sextupole harmonics, and guidance from tracking simulations. The practicality of each will be discussed.
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.
An energy recovery linac (ERL) is one of the candidates for an upgrade of the Advanced Photon Source (APS). In addition to the APS ring and full-energy linac, our design also includes a large turn-around arc that could accommodate new x-ray beamlines as well. In total, the beam trajectory length would be close to 3 km. The ERL lattice has strong focusing to limit emittance growth, and it includes strong sextupoles to keep beam energy spread under control and minimize beam losses. As in storage rings, trajectory errors in sextupoles will result in lattice perturbations that would affect delivered x-ray beam properties. In storage rings, the response matrix fit method is widely used to measure and correct linear lattice errors. Here, we explore the application of the method to the linear lattice correction and coupling correction of an ERL.
LNLS, Campinas
The synchrotron machine at the Brazilian Synchrotron Light Laboratory (LNLS) is a storage ring for 1.37 GeV electrons composed of six DBA cells whose lengths add up to around 93 meters of circumference. There are 18 horizontal and 24 vertical correctors available in the ring for correcting the orbit as measured at 24 BPMs. In the past, stored beams have been delivered which successfully fulfilled user’s stability and emittance demands. This has been accomplished by fine tuning the machine using mostly measured beam parameters. The ongoing commissioning of the a new undulator beamline, which is expected to become the most demanding one, puts pressure in the direction of improving existing models of the ring optics in order to envisage ways of improving beam quality. In this paper we discuss preliminary tests with LOCO* at the LNLS. We report on the impact of the calibration of the machine based on LOCO calculations through the analysis of standard experiments and optics parameters such as beta-beat reduction, improvement of life-time and so on.
*LOCO in the Beam Dynamics Newsletter, 44, ICFA, December 2007.
BNL, Upton, Long Island, New York
Fermilab, Batavia
The use of single stage bunch compressor (BC) in the International Linear Collider (ILC)* Damping Ring to the Main Linac beamline (RTML) requires new design for the extraction line (EL). The EL located downstream of the BC will be used for both an emergency abort dumping of the beam and the tune-up continuous train-by-train extraction. It must accept both compressed and uncompressed beam with energy spread of 3.54% and 0.15% respectively. In this paper we report design that allowed minimizing the length of such extraction line while offsetting the beam dumps from the main line by 5m distance required for acceptable radiation level in the service tunnel. Proposed extraction line can accommodate beams with different energy spreads at the same time providing the beam size suitable for the aluminum ball dump window.
*N. Phinney et al., “International Linear Collider Reference Design Report: Accelerator”, SLAC-R-857C
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.
DESY, Hamburg
The post-linac collimation system should simultaneously fulfil several different functions. In first place, during routine operations, it should remove with high efficiency off-momentum and large amplitude halo particles, which could be lost inside undulator modules and become source of radiation-induced demagnetization of the undulator permanent magnets. The system also must protect the undulator modules and other downstream equipment against mis-steered and off-energy beams in the case of machine failure without being destroyed in the process. From beam dynamics point of view, the collimation section should be able to accept bunches with different energies (up to ± 1.5% from nominal energy) and transport them without deterioration not only of transverse, but also of longitudinal beam parameters. In this article we present the optics solution for the post-linac collimation system which fulfils all listed above requirements.
CERN, Geneva
As for the final focus systems of linear colliders, the chromatic aberrations induced by low-beta insertions can seriously limit the performance of circular colliders. The impact is two-fold: (1) a substantial off-momentum beta-beating wave travelling all around of the ring leading to a net reduction of the mechanical aperture of the low-beta quadrupoles but also impacting on the hierarchy of the collimator and protection devices of the machine, (2) a huge non-linear chromaticity, essentially Q’’ and Q’’’, which, when combined with the geometric non-linear imperfection of the machine could substantially reduce the momentum acceptance of the ring by sending slightly off-momentum particles towards non-linear resonances. These effects will be analyzed and illustrated in the framework of the LHC insertions upgrade and a strategy for correction will be developed, requiring a deep modification of the LHC overall optics.
CERN, Geneva
BNL, Upton, Long Island, New York
The effect of magnet misalignments in the beam orbit and linear optics functions are reviewed and correction schemes are applied to the negative momentum compaction lattices of PS2. Chromaticity correction schemes are also proposed and tested with respect to off-momentum optics properties. The impact of the correction schemes in the dynamic aperture of the different lattices is finally evaluated.
Fermilab, Batavia
Funding: Work supported by Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Recent advances in the HTS magnet technology and ionization cooling theory have re-launched the interest of the physics community in the realization of a high energy, high luminosity Muon Collider (MC). The large muon energy spread requires large momentum acceptance and the required luminosity calls for beta* in the mm range. To avoid luminosity degradation due to the hour-glass effect, the bunch length must be comparatively small. To keep the needed RF voltage inside feasible limits the momentum compaction factor must be as small as possible. Under these circumstances chromatic effects correction, energy acceptance, dynamic aperture and longitudinal motion stability are main issues of a MC design. In this paper we give an overview of various lattice designs toward a high luminosity, large energy acceptance MC currently under study at Fermilab.
Fermilab, Batavia
Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Muon collider is a promising candidate for the next energy frontier machine. In order to obtain peak luminosity of the order of 1035/cm2/s in the TeV energy range the beta function at the interaction point should be smaller than 1cm. To obtain correspondingly small bunch length with a reasonable RF voltage (within 1GV) the momentum compaction factor should be smaller than 10-4 in the momentum range ~1%. The lattice design must also provide sufficient dynamic aperture for ~20 microns normalized beam emittance and minimum possible circumference. Together these requirements present a challenge which has never been met before. We offer a solution to this problem which has the following distinctive features: i) chromatic compensation achieved with sextupoles and dispersion generating dipoles placed near the IR quadrupoles (not in a special section), ii) low value of momentum compaction factor obtained by balancing positive contribution from the arcs with negative contribution from the suppressors of the generated in the IR dispersion. Theoretical aspects and various options will be discussed.
Fermilab, Batavia
Funding: Work supported by the Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy.
A transition-free lattice is a basic requirement of a high-intensity medium-energy (several GeV) proton synchrotron in order to eliminate beam losses during transition crossing. An 8 GeV synchrotron is proposed as a principal component in an alternative hybrid design of Project-X. This machine would be housed in the Fermilab antiproton source enclosure replacing the present Debuncher. A simple doublet lattice with high transition gamma has been designed. It uses just one type of dipoles and one type of quadrupoles (QF and QD are of the same length). It has no transition crossing. It has a triangular shape with three zero dispersion straight sections, which can be used for injection, extraction, RF and collimators. The beta-functions and dispersion are low. This lattice has plenty of free space for correctors and diagnostic devices, as well as good optical properties including large dynamic aperture, weak dependence of lattice functions on amplitude and momentum deviation.
*W. Chou, “An Alternative Approach to Project X,” this conference.
GSI, Darmstadt
The GSI heavy ion synchrotron SIS18 will be used as a booster for the SIS100 synchrotron of the new FAIR facility. The linear corrections and measurements are a necessary step before the nonlinear field errors can be applied. A tune response to a change in a sextupole magnet strength for a certain Closed Orbit (CO) deformation is used to verify beta-functions of the SIS18 model at the location of the ring's sextupoles for chromaticity correction. The progress in development of Nonlinear Tune Response Matrix (NTRM) technique to diagnose nonlinear field components is 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.
BNL, Upton, Long Island, New York
We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a linear matrix analysis method in linear algebra. Using the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of analysis of eigenvectors in Jordan spaces which is widely used in conventional linear algebra.
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.
GSI, Darmstadt
The FAIR Storage Rings (CR, RESR and NESR) are designed for efficient cooling, accumulation, deceleration and performing nuclear physics experiments with antiproton and rare isotopes beams. Tracking studies for all these rings have been performed to estimate the dynamic aperture and other properties of beam stability depending on the low and high field multipole components, fringe fields and field interference. The multipole limits have to be determined in order to provide a reasonable estimate of the stability boundary and needed correction of the low field multipoles. We report on quantitative studies of the effects of multipoles on the dynamic aperture of the rings, and show that the systematic multipole components in the present magnet designs are unlikely to impose a severe limitation.
JAEA/TARRI, Gunma-ken
CNS, Saitama
It is possible to fold the tails of the transverse beam profile into the inside, or even to uniformize the beam distribution in the properly-designed nonlinear beam transport system. A two-dimensionally uniform beam profile was formed using sextupole and octupole magnets at the azimuthally-varying-field cyclotron facility of Japan Atomic Energy Agency. Such a uniform beam exhibits a unique feature in the viewpoint of a uniform irradiation system; as compared to the raster scanning system, it enables us to perform uniform irradiation over the whole area of a large sample at a constant particle fluence rate. For the application of materials sciences, uniformization of heavy-ion beams as well as protons has been performed. In order to reduce undesirable beam halos at the target, tail-folding of the spot beam is also planed using the nonlinear focusing method.
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).
SOLEIL, Gif-sur-Yvette
SOLEIL, the French 2.75 GeV third generation synchrotron light source, was commissioned 3 years ago. Thanks to beam-based measurements, the theoretical model of the storage ring lattice model has been improved. First, the quadrupole lengths in the hard edge model were finely tuned to get good agreement with the experimental measurements of betatron tunes for different optics. Second, the non-linear model was modified to better fit with beam-based on-momentum frequency map measurements. A thick sextupole model has been introduced in addition to the non-linear effect of the fringe field in quadrupoles. Simulated and measured tune shifts with transverse amplitudes are then compared. Finally a coupled machine model has been built thanks to crosstalk closed orbit acquisitions. A comparison with another model which is based on turn by turn beam position monitor data is presented. As a validation check, the coupling effect of the 10 m long HU640 undulator is evaluated through these coupled models.
KEK, Ibaraki
The University of Liverpool, Liverpool
SLAC, Menlo Park, California
One of the goals of the Accelerator Test Facility (ATF) at KEK is to demonstrate ultra-low vertical emittance for linear colliders. Highly precise correction of the vertical dispersion and betatron coupling will be needed to achieve the target of 2 pm (which will be required for ILC). Optics correction and tuning must be supported by an accurate model, which can be developed from a variety of beam measurements, including orbit response to dipole kicks, beta functions at the quadrupoles, etc. Here, we report experimental data and the status of the model and low-emittance tuning.
SLAC, Menlo Park, California
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
KEK, Ibaraki
LAL, Orsay
UMAN, Manchester
CERN, Geneva
Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515
Using a new extraction line currently being commissioned, the ATF2 experiment plans to test a novel compact final focus optics design using a local chromaticity correction scheme, such as could be used in future linear colliders*. Using a 1.3 GeV beam of ~30nm normalised vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical IP waist of 35nm. We discuss our planned strategy, implementation details and early experimental results for tuning the ATF2 beam to meet the primary goal. These optics require uniquely tight tolerances on some magnet strengths and positions, we discuss efforts to re-match the optics to meet these requirements using high-precision measurements of key magnet elements. We simulated in detail the tuning procedure using several algorithms and different code implementations for comparison from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within 10% of the design optics value in at least 90% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks.
*"ATF2 Proposal", ATF2 Collaboration (Boris Ivanovich Grishanov et al.)., KEK-REPORT-2005-2, Aug 23, 2005.
SSRF, Shanghai
Funding: SSRF
The ssrf is a 3rd generation light source under commissioning. The commissioning of the storage ring has progressed very well so far. The periodicity and symmetry of the linear optics in a real storage ring is important, however maybe be broken by various errors, such as field errors, manufactured errors. A distorted linear optics can excite stronger nonlinear resonances, which will reduce the storage ring dynamic aperture and make the storage ring suffer from low injection efficiency and short beam lifetime. Therefore, it is necessary to restore the designed periodicity or symmetry of the linear optics based on measured closed orbit distortion. The calibration procedure can be done by using LOCO (the Linear Optics from Closed Orbit). After fitting the measured response matrix by the model one, the linear optics of the storage ring is calibrated. And different operation modes have been also measured and calibrated.
USTC/NSRL, Hefei, Anhui
In order to meet the increasing requirements of synchrotron radiation users, a new plan of VUV and soft X-ray light source, named Hefei Advanced Light Source (HALS), is brought forward by National Synchrotron Radiation Laboratory (NSRL). This 1.5GeV storage ring with ultra low emittance 0.2nmrad consists of 18 combined FBA cells and the circumference is 388m. Strong enough quadrupoles and sextupoles must be needed for getting such low emittance lattice, which will lead beam close orbit distortions’ (COD) sensitivity to the field and alignment errors in magnets. Estimation of the COD from various error sources is investigated. Using orbit response matrix and singular value decomposition method, the distribution of beam position monitors and the location of correctors are reported in the paper. Simulation proves that COD can be corrected down to 60 microns level. In the same time the corrector strengths are weaker enough in the correction scheme.
SLAC, Menlo Park, California
The Flight Simulator is a Matlab middleware layer which uses the Lucretia beam tracking engine and a lower level EPICS control system to allow the development of beam control and monitoring algorithms in a simulation environment that appears identical to the that of the control room. The goal of ATF2 is to test a novel compact final final focus optics design intended for use in future linear colliders. The newly designed extraction line and final focus system will be used to produce a 37nm vertical waist from the extracted beam. Alignment of the magnetic elements is of vital importance for this goal and it is expected that beam-based alignment (BBA) techniques will be necessary to achieve the necessary tolerances. This paper describes a package for the beam-based alignment of quadrupole and sextupole magnets in the ATF2 damping ring, extraction line, and final focus system. It brings together several common techniques for the alignment of magnetic elements, and has been implemented as a GUI-based tool that may be used on its own, or integrated with other routines. The design of this package is described, and simulation and beam results are shown.
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.