2011 Particle Accelerator Conference - List of Keywords (sextupole)

Paper	Title	Other Keywords	Page
MOODN5	Chromaticity Correction for a Muon Collider Optics	optics, quadrupole, collider, luminosity	79
	E. Gianfelice-Wendt, Y. Alexahin, V.V. Kapin Fermilab, Batavia, USA
	Funding: Work supported by Fermi Research Alliance, LLC under DE-AC02-07CH11359 with the U.S. DOE Muon Collider (MC) is a promising candidate for the next energy frontier machine. However, in order to obtain peak luminosity in the 10³⁴cm^-2s^-1 range the collider lattice design must satisfy a number of stringent requirements. In particular the expected large momentum spread of the muon beam and the very small β* call for a careful correction of the chromatic effects. Here we present a particular solution for the interaction region (IR) optics whose distinctive feature is a three-sextupole local chromatic correction scheme. The scheme may be applied to other future machines where chromatic effects are expected to be large.
	Slides MOODN5 [0.554 MB]

MOODS2	Nonlinear Resonance Measurements and Correction in Storage Rings	resonance, betatron, dipole, storage-ring	88
	R. Bartolini Diamond, Oxfordshire, United Kingdom
	Several theoretical and experimental techniques have been developed in recent years to correct the detrimental effect of nonlinear resonances on dynamic aperture, beam lifetime, injection efficiency and beam loss distribution. These issues are equally important in synchrotron light sources and high energy colliders. We present the latest theoretical and experimental results obtained at the Diamond light source on the characterization of the nonlinear resonances and on the comparison between the nonlinear model of the machine to the real accelerator.
	Slides MOODS2 [3.159 MB]

MOP169	Optical Beam Diagnostics at ELSA	emittance, synchrotron, quadrupole, diagnostics	408
	S. Zander, F. Frommberger, P. Haenisch, W. Hillert, S. Patzelt ELSA, Bonn, Germany
	Funding: Funded by the DFG within the SFB / TR 16. The Electron Stretcher Facility ELSA consists of several accelerator stages, the last one being a storage ring providing a beam of polarized electrons of up to 3.5 GeV. At ELSA various diagnostic devices based on synchrotron radiation are installed or planned. A new beamline at the storage ring designed for high resolution diagnostics in the transversal plane will be presented. The measurement setup is sensitive at the UV range of the synchrotron light spectrum. Upgrade measures aiming to extend the diagnostic possibilities to the longitudinal direction will be detailed. In the external beamlines beam currents below 1 nA are delivered to photo production experiments. Beam profiles are detected using dedicated synchrotron light monitors optimized for low intensities. The characteristics of the monitors will be described. In addition, beam parameters derived from the measured profiles at different resonance extraction setups will be shown.

TUODN4	Dynamic Aperture Optimization using Genetic Algorithms	lattice, dynamic-aperture, emittance, storage-ring	793
	C. Sun, H. Nishimura, D. Robin, C. Steier, W. Wan LBNL, Berkeley, California, USA
	Genetic Algorithm is successfully applied to optimize dynamic aperture of lattices for ALS future upgrades. It is demonstrated that the optimization using total diffusion rate as objective has a better performance than the one using dynamic aperture area. The linear and non-linear properties of the lattice are optimized simultaneously, and trade-offs are found among the small emittance, low-beta function and large dynamic aperture. These trade-offs can provide us a guideline to choose a candidate lattice for ALS future upgrades.
	Slides TUODN4 [1.781 MB]

TUP145	Introduction to HLSII Storage Ring Conventional Magnets	quadrupole, dipole, storage-ring, synchrotron	1100
	H. Zhang, G. Feng, W.W. Li, W. Li, J.J. Liang, L. Wang, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	HLS (Hefei Light Source) is a dedicated synchrotron radiation research facility, whose emittance is relatively large. In order to improve the performance of HLS, especially getting higher brilliance synchrotron radiation and increasing the number of straight section for insertion devices, an upgrade project named HLSII will be proceeded soon. The storage ring lattice comprises 8 dipoles, 32 quadrupoles and 32 combined function sextupoles. Design and analysis of the magnets are showed in the paper. the multipurpose combined function magnet is the first one designed and used in China. Mechanical design and fabrication procedures for the magnets are presented also.

TUP244	Magnetic Simulation of an Electromagnetic Variably Polarizing Undulator *	simulation, undulator, polarization, photon	1289
	M.S. Jaski, R.J. Dejus, E.R. Moog ANL, Argonne, USA
	Development of an all-electromagnetic variable polarizing undulator is underway at the Advanced Photon Source (APS). This device has a set of Bx poles and coils and a set of By poles and coils. The Bx coils are powered separately from the By coils. Modifying the geometry of the Bx coils or poles changes not only the Bx field but changes the By field as well and vice-versa. Magnetic modeling with OPERA 3-D software was used to optimize the coil and pole geometries. Results of the magnetic field simulation and optimization are presented in this paper. * Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract number DE-AC02-06CH11357.

WEP005	Modeling the Low-Alpha-Mode at ANKA with the Accelerator Toolbox	quadrupole, optics, synchrotron, dipole	1510
	M. Klein, N. Hiller, A. Hofmann, E. Huttel, V. Judin, B. Kehrer, S. Marsching, A.-S. Müller KIT, Karlsruhe, Germany K.G. Sonnad CLASSE, Ithaca, New York, USA
	The ANKA storage ring is operated frequently with low momentum compaction lattices to produce short bunches for the generation of coherent synchrotron radiation in the THz range. The bunch length can be varied in steps from one centimeter down to the sub millimeter level. These low alpha optics are modeled by using the Matlab based tools, Accelerator Toolbox (AT) and LOCO. The results are compared with measurements such as orbit response matrices, dispersion and chromaticity. This paper provides results of a study on the feasibilities as well as limitations of the measurements and calculations.

WEP017	Re-Examination of the NSLS-II Magnet Multipole Specifications	multipole, quadrupole, magnet-design, lattice	1531
	W. Guo, A.K. Jain, S. Krinsky, S. Seiler, J. Skaritka, C.J. Spataro BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy The NSLS-II magnet multipole specifications were determined based on analysis of nonlinear beam dynamics. The required field quality does not exceed what was specified for the existing third-generation light sources. While the prototype magnets have met these specifications, the magnets from mass production could potentially have bigger errors which exceed certain tolerances. In this paper we discuss the results of recent calculations to provide further insight into the acceptable range of the magnet multipoles based on the physics requirements.

WEP018	Optics Error Measurements in the AGS for Polarized Proton Operation	survey, quadrupole, betatron, closed-orbit	1534
	V. Schoefer, L. A. Ahrens, K.A. Brown, J.W. Glenn, H. Huang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A large distortion of the vertical beta function became evident in the Brookhaven AGS during the 2010 polarized proton run. This paper describes the beam measurements and model calculations made to verify the distortion of the optics, to infer possible sources and to explore correcting strategies. The optics distortion is only apparent when operating with a betatron tune very near the integer (as required for polarization preservation during acceleration in the AGS) and with the lattice chromaticity sextupoles powered. The measurements indicate a small (on the order of millimeters) unexpected systematic horizontal closed orbit displacement in the sextupoles that is not evident in beam position monitor measurements. Motivated especially by these observations a complete survey of the AGS was performed during the 2010 shutdown period.&nb sp; The results of that survey and their impact on the observed optical errors in the AGS are included.

WEP030	Direct Focusing Error Correction with Ring-wide TBT Beam Position Data	quadrupole, lattice, focusing, simulation	1546
	M.-J. Yang Fermilab, Batavia, USA
	Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in studying machine optics. Hundreds and thousands of turns of data are taken in just few tens of milliseconds. With beam in free oscillation and covering all positions and angles at every location focusing error diagnosis can be made almost instantly. This paper describes a new approach that observes focusing error collectively over all available TBT data to find the optimized quadrupole strength, one location at a time. Example will be shown and other issues will be discussed.

WEP062	Optimized Sextupole Configurations for Sextupole Magnet Failure in Top-up Operation at the APS*	injection, lattice, power-supply, dynamic-aperture	1588
	V. Sajaev ANL, Argonne, USA
	Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Recently there was a situation at the APS when one sextupole power supply failed during top-up operation (all magnets at the APS have separate power supplies). The beam was not lost but the lifetime decreased significantly to the point where it was hard for the injectors to provide enough charge for top-up injections. Luckily, the power supply was able to reset quickly, and the operation was not compromised. One can anticipate similar failures in the future when it would not be possible to reset the power supply. In such a case, the APS would need to operate with lower lifetime until the next intervention period. Here we present an optimization of the sextupole distribution in the vicinity of the failed sextupole that allows us to partially recover the lifetime. A genetic optimization algorithm that involves simultaneous optimization of the dynamic and energy apertures was used. Experimental tests are also presented. M. Borland et al., "Application of Direct Methods of Optimizing Storage Ring Dynamic and Momentum Apertures," Proc. ICAP2009, to be published.

WEP063	Tracking Particles Through A General Magnetic Field	lattice, storage-ring, photon, HOM	1591
	A. Xiao, M. Borland, L. Emery, Y. Wang ANL, Argonne, USA
	Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A method that tracks particles directly through a general magnetic field described in a 3D field table was added to the code elegant recently. It was realized by converting an arbitrary particle's motion to a combination of free-drift motion and centripetal motion through the coordinate system rotation and using a general linear interpolation tool developed at the Advanced Photon Source (APS). This method has been tested by tracking particles through conventional magnetic elements (dipole, sextupole, etc.) to verify reference coordinate system conversions, tracking accuracy, and long-term tracking stability. Results show a very good agreement between this new method and the traditional method. This method is not designed to replace mature traditional methods that have been used in most tracking codes. Rather, it is useful for magnets with complicated field profiles or for studying edge effects.

WEP065	Multiobjective Dynamic Aperture Optimization at NSLS-II	lattice, quadrupole, dipole, damping	1597
	L. Yang, W. Guo, S. Krinsky, Y. Li BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In this paper we present a multiobjective approach to the dynamic aperture (DA) optimization. Taking the NSLS- II lattice as an example, we have used both sextupoles and quadrupoles as tuning variables to optimize both on-momentum and off-momentum DA. The geometric and chromatic sextupoles are used for nonlinear properties while the tunes are independently varied by quadrupoles. The dispersion and emittance are fixed during tunes variation. The algorithms, procedures, performances and results of our optimization of DA will be discussed and they are found to be robust, general and easy to apply to similar problems.

WEP087	Numerical Studies of Non-Linear Dynamics in BEP	resonance, positron, coupling, booster	1636
	I. Koop, E. Perevedentsev BINP SB RAS, Novosibirsk, Russia T.V. Zolkin University of Chicago, Chicago, Illinois, USA
	An analysis of the dependence of experimental captured positron current data from the booster storage ring BEP (VEPP-2000 facility, BINP, Russia) on the working point position on the frequency map has uncovered a great number of different non-linear resonances. The number of captured positrons after a single injection is observed to be much less than the expected value. It is anticipated that the high degree of symmetry in the magnet system of BEP, however, should lead to the suppression of such resonances. To study this discrepancy, numerical simulations of positron beam movement under different perturbations to account for potential errors in magnetic field gradient of non-linear elements and errors in their angular location are used. The findings of this research provide qualitative explanations of the experimental work diagram and answers to two main questions, specifically “Why in the absence of skew-sextupoles in structure and small coupling are strong skew-sextupole resonances observed” and “Why skew-sextupole resonances are stronger than sextupole ones of the same harmonic”. A comparison between simulation results and analytical estimates is also presented.

WEP092	Space Charge Effect of the High Intensity Proton Beam during the Resonance Extraction for the MU2E Experiment at Fermilab	space-charge, extraction, septum, resonance	1645
	C.S. Park, J.F. Amundson, J.A. Johnstone, V.P. Nagaslaev, S.J. Werkema Fermilab, Batavia, USA
	The proposed Mu2e experiment to search for direct μ to e conversion at Fermilab plans slow, resonant extraction of a beam with 3× 10¹² protons from the Debuncher ring. Space charge of this high intensity beam is a critical factor, since it induces significant betatron tune spread and consequently affects resonance extraction processes, such as spill uniformity and beam losses. This study shows the multi-particle simulation results in the early stages of resonance extraction and spill uniformity in the presence of 2D and 3D space charge effects.

THP059	Chromatic Analysis and Possible Local Chromatic Correction in RHIC	lattice, quadrupole, resonance, betatron	2235
	Y. Luo, W. Fischer, X. Gu, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In this article we will answer the following questions: 1) what is the source of second order chromaticities in RHIC? 2) what is the dependence of second order chromaticity on the on-momentum β-beat? 3) what is the dependence of second order chromaticity on β* at IP6 and IP8? To answer these questions, we use the perturbation theory to numerically calculate the contributions of each quadrupole and sextupole to the first, second, and third order chromaticities. Possible methods to locally reduce chromatic effects in RHIC rings are shortly discussed.

THP061	Mimicking Bipolar Sextupole Power Supplies for Low-energy Operations at RHIC	dipole, ion, luminosity, background	2241
	C. Montag, D. Bruno, A.K. Jain, G. Robert-Demolaize, T. Satogata, S. Tepikian BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. RHIC operated at energies below the nominal ion injection energy of E=9.8 GeV/u in 2010. Earlier test runs and magnet measurements indicated that all defocusing sextupole unipolar power supplies should be reversed to provide the proper sign of chromaticity. However, vertical chromaticity at E=3.85 GeV/u with this power supply configuration was still not optimal. This uncertainty inspired a new machine configuration where only half of the defocusing sextupole power supplies were reversed, taking advantage of the flexibility of the RHIC nonlinear chromaticity correction system to mimic bipolar sextupoles. This configuration resulted in a 30 percent luminosity gain and eliminated the need for further polarity changes for later 2010 low energy physics operations. Here we describe the background to this problem, operational experience, and RHIC online model changes to implement this solution.

THP065	Advances in High-Order Interaction Region Nonlinear Optics Correction at RHIC	octupole, coupling, collider, interaction-region	2252
	C.M. Zimmer, S. Binello, M.G. Minty, F.C. Pilat BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A method to indirectly measure and deterministically correct the higher order magnetic errors of the final focusing magnets in the Relativistic Heavy Ion Collider has been in place for several years at BNL. This method yields control over the effects of multi-pole errors through application of closed orbit bumps followed by analysis and correction of the resulting betatron tune shifts using multi-pole correctors. The process has recently been automated in order to provide more efficient and effective corrections. The tune resolution along with the reliability of tune measurements has also been improved significantly due to advances/upgrades in the betatron tune measurement system employed at RHIC (BBQ). Here we describe the foundation of the IR bump method, followed by recent improvements along with experimental data.

THP071	Interaction Region Design of Super-CT-Factory in Novosibirsk	quadrupole, interaction-region, factory, solenoid	2264
	A.V. Bogomyagkov, E.B. Levichev, P.A. Piminov BINP SB RAS, Novosibirsk, Russia
	The interaction region of the Super-CT-factory is designed to bring stored electron-positron beams into collision with luminosity of 10³⁵ cm^-2sec^-1. To achieve this a waist collision scheme is implemented, which requires cross-angle collision with high Piwinski angle. The small values of the beta functions at the interaction point and distant final focus lenses are the reasons for high nonlinear chromaticity limiting energy acceptance of the whole ring. The present design allows correction of linear and nonlinear chromaticity of beta functions and of betatron tune advances, correction of second and third order geometrical aberrations from the strong sextupoles pairs, satisfies geometrical constraints, embraces realistic design of final focus quadrupoles and as close as possible positioning of crab sextupole to interaction point.

THP105	Final Design of ILC RTML Extraction Line for Single Stage Bunch Compressor	extraction, kicker, septum, damping	2321
	S. Seletskiy BNL, Upton, Long Island, New York, USA N. Solyak Fermilab, Batavia, USA
	The use of single stage bunch compressor (BC) in the International Linear Collider (ILC) [1] 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 the final 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.

THP119	Potential Two-fold Reduction of Advanced Photon Source Emittance using Orbit Displacement	lattice, emittance, quadrupole, damping	2339
	M. Borland ANL, Argonne, USA
	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 Advanced Photon Source (APS) is a 7-GeV electron storage ring light source that operates with an effective emittance of 3.1 nm using optics with distributed dispersion. Lower emittance is desirable for some x-ray experiments, but is difficult using conventional optics adjustments because of the required strength of quadrupoles and sextupoles. Changing the damping partition number by changing the rf frequency is another approach, but is incompatible with distributed dispersion because it would require simultaneous realignment of all APS beamlines. In this paper, we evaluate a new approach to changing the damping partition number using a systematic orbit bump in all sectors.

THP125	Multi-objective Optimization of a Lattice for Potential Upgrade of the Advanced Photon Source*	lattice, optics, dynamic-aperture, quadrupole	2354
	V. Sajaev, M. Borland, L. Emery, A. Xiao ANL, Argonne, USA
	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 Advanced Photon Source (APS) is a 7-GeV storage ring light source that has been in operation for over a decade. In the near future, the ring may be upgraded, including changes to the lattice such as provision of several long straight sections (LSSs). Use of deflecting cavities for generation of short x-ray pulses is also considered. Because APS beamlines are nearly fully built out, we have limited freedom to place LSSs in a symmetric fashion. Arbitrarily placed LSSs will drastically reduce the symmetry of the optics and would typically be considered unworkable. We apply a recently developed multi-objective direct optimization technique that relies on particle tracking to compute the dynamic aperture and Touschek lifetime. We show that this technique is able to tune sextupole strengths and select the working point in such a way as to recover the dynamic and momentum acceptances. We also show the results of experimental tests of lattices developed using these techniques.

THP189	Low Horizontal Beta Function in Long Straights of the NSLS-II Lattice	lattice, injection, dynamic-aperture, insertion	2471
	F. Lin, J. Bengtsson, W. Guo, S. Krinsky, Y. Li, L. Yang BNL, Upton, New York, USA
	Funding: Work supported by U.S. DOE, Contract No. DE-AC02-98CH10886 The NSLS-II storage ring lattice is comprised of 30 DBA cells arranged in 15 superperiods. There are 15 long straight sections (9.3m) for injection, RF and insertion devices and 15 shorter straights (6.6m) for insertion devices. In the baseline lattice, the short straights have small horizontal and vertical beta functions but the long straights have large horizontal beta function optimized for injection. In this note, we explore the possibility of maintaining three long straights with large horizontal beta function while providing the other 12 long straights with smaller horizontal beta function to optimize the brightness of insertion devices. Our study considers the possible linear lattice solutions as well as characterizing the nonlinear dynamics. Results are reported on optimizations of dynamic aperture required for good injection efficiency and adequate Touschek lifetime.

THP214	Pulsed Multipole Injection for the MAX IV Storage Rings	injection, storage-ring, multipole, septum	2522
	S.C. Leemann MAX-lab, Lund, Sweden
	The MAX IV facility presently under construction will include two storage rings for the production of synchrotron radiation. The 3 GeV ring will house insertion devices for the production for x-rays while the 1.5 GeV ring will serve UV and IR users. Both rings will be operated at a constant 500 mA of stored current with top-up shots supplied by the 3.5 GeV MAX IV linac acting as a full-energy injector. So far, injection into both storage rings has been designed using a conventional approach: a closed four-kicker injection bump brings the stored beam to the septum blade where the injected bunches are captured in a single turn. Recently, studies have been carried out to investigate the feasibility of using a pulsed multipole for injection into the storage rings. Pulsed multipole injection does not require an injection bump and has the potential to make top-up injection transparent to users. This paper reports on these studies and summarizes requirements for the pulsed sextupole magnet to be installed for injection into the MAX IV storage rings.

Paper

Title

Other Keywords

Page

MOODN5

Chromaticity Correction for a Muon Collider Optics

optics, quadrupole, collider, luminosity

79

E. Gianfelice-Wendt, Y. Alexahin, V.V. Kapin
Fermilab, Batavia, USA

Funding: Work supported by Fermi Research Alliance, LLC under DE-AC02-07CH11359 with the U.S. DOE
Muon Collider (MC) is a promising candidate for the next energy frontier machine. However, in order to obtain peak luminosity in the 10³⁴cm^-2s^-1 range the collider lattice design must satisfy a number of stringent requirements. In particular the expected large momentum spread of the muon beam and the very small β* call for a careful correction of the chromatic effects. Here we present a particular solution for the interaction region (IR) optics whose distinctive feature is a three-sextupole local chromatic correction scheme. The scheme may be applied to other future machines where chromatic effects are expected to be large.

Slides MOODN5 [0.554 MB]

MOODS2

Nonlinear Resonance Measurements and Correction in Storage Rings

resonance, betatron, dipole, storage-ring

88

R. Bartolini
Diamond, Oxfordshire, United Kingdom

Several theoretical and experimental techniques have been developed in recent years to correct the detrimental effect of nonlinear resonances on dynamic aperture, beam lifetime, injection efficiency and beam loss distribution. These issues are equally important in synchrotron light sources and high energy colliders. We present the latest theoretical and experimental results obtained at the Diamond light source on the characterization of the nonlinear resonances and on the comparison between the nonlinear model of the machine to the real accelerator.

Slides MOODS2 [3.159 MB]

MOP169

Optical Beam Diagnostics at ELSA

emittance, synchrotron, quadrupole, diagnostics

408

S. Zander, F. Frommberger, P. Haenisch, W. Hillert, S. Patzelt
ELSA, Bonn, Germany

Funding: Funded by the DFG within the SFB / TR 16.
The Electron Stretcher Facility ELSA consists of several accelerator stages, the last one being a storage ring providing a beam of polarized electrons of up to 3.5 GeV. At ELSA various diagnostic devices based on synchrotron radiation are installed or planned. A new beamline at the storage ring designed for high resolution diagnostics in the transversal plane will be presented. The measurement setup is sensitive at the UV range of the synchrotron light spectrum. Upgrade measures aiming to extend the diagnostic possibilities to the longitudinal direction will be detailed. In the external beamlines beam currents below 1 nA are delivered to photo production experiments. Beam profiles are detected using dedicated synchrotron light monitors optimized for low intensities. The characteristics of the monitors will be described. In addition, beam parameters derived from the measured profiles at different resonance extraction setups will be shown.

TUODN4

Dynamic Aperture Optimization using Genetic Algorithms

lattice, dynamic-aperture, emittance, storage-ring

793

C. Sun, H. Nishimura, D. Robin, C. Steier, W. Wan
LBNL, Berkeley, California, USA

Genetic Algorithm is successfully applied to optimize dynamic aperture of lattices for ALS future upgrades. It is demonstrated that the optimization using total diffusion rate as objective has a better performance than the one using dynamic aperture area. The linear and non-linear properties of the lattice are optimized simultaneously, and trade-offs are found among the small emittance, low-beta function and large dynamic aperture. These trade-offs can provide us a guideline to choose a candidate lattice for ALS future upgrades.

Slides TUODN4 [1.781 MB]

TUP145

Introduction to HLSII Storage Ring Conventional Magnets

quadrupole, dipole, storage-ring, synchrotron

1100

H. Zhang, G. Feng, W.W. Li, W. Li, J.J. Liang, L. Wang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

HLS (Hefei Light Source) is a dedicated synchrotron radiation research facility, whose emittance is relatively large. In order to improve the performance of HLS, especially getting higher brilliance synchrotron radiation and increasing the number of straight section for insertion devices, an upgrade project named HLSII will be proceeded soon. The storage ring lattice comprises 8 dipoles, 32 quadrupoles and 32 combined function sextupoles. Design and analysis of the magnets are showed in the paper. the multipurpose combined function magnet is the first one designed and used in China. Mechanical design and fabrication procedures for the magnets are presented also.

TUP244

Magnetic Simulation of an Electromagnetic Variably Polarizing Undulator *

simulation, undulator, polarization, photon

1289

M.S. Jaski, R.J. Dejus, E.R. Moog
ANL, Argonne, USA

Development of an all-electromagnetic variable polarizing undulator is underway at the Advanced Photon Source (APS). This device has a set of Bx poles and coils and a set of By poles and coils. The Bx coils are powered separately from the By coils. Modifying the geometry of the Bx coils or poles changes not only the Bx field but changes the By field as well and vice-versa. Magnetic modeling with OPERA 3-D software was used to optimize the coil and pole geometries. Results of the magnetic field simulation and optimization are presented in this paper.
* Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract number DE-AC02-06CH11357.

WEP005

Modeling the Low-Alpha-Mode at ANKA with the Accelerator Toolbox

quadrupole, optics, synchrotron, dipole

1510

M. Klein, N. Hiller, A. Hofmann, E. Huttel, V. Judin, B. Kehrer, S. Marsching, A.-S. Müller
KIT, Karlsruhe, Germany
K.G. Sonnad
CLASSE, Ithaca, New York, USA

The ANKA storage ring is operated frequently with low momentum compaction lattices to produce short bunches for the generation of coherent synchrotron radiation in the THz range. The bunch length can be varied in steps from one centimeter down to the sub millimeter level. These low alpha optics are modeled by using the Matlab based tools, Accelerator Toolbox (AT) and LOCO. The results are compared with measurements such as orbit response matrices, dispersion and chromaticity. This paper provides results of a study on the feasibilities as well as limitations of the measurements and calculations.

WEP017

Re-Examination of the NSLS-II Magnet Multipole Specifications

multipole, quadrupole, magnet-design, lattice

1531

W. Guo, A.K. Jain, S. Krinsky, S. Seiler, J. Skaritka, C.J. Spataro
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
The NSLS-II magnet multipole specifications were determined based on analysis of nonlinear beam dynamics. The required field quality does not exceed what was specified for the existing third-generation light sources. While the prototype magnets have met these specifications, the magnets from mass production could potentially have bigger errors which exceed certain tolerances. In this paper we discuss the results of recent calculations to provide further insight into the acceptable range of the magnet multipoles based on the physics requirements.

WEP018

Optics Error Measurements in the AGS for Polarized Proton Operation

survey, quadrupole, betatron, closed-orbit

1534

V. Schoefer, L. A. Ahrens, K.A. Brown, J.W. Glenn, H. Huang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A large distortion of the vertical beta function became evident in the Brookhaven AGS during the 2010 polarized proton run. This paper describes the beam measurements and model calculations made to verify the distortion of the optics, to infer possible sources and to explore correcting strategies. The optics distortion is only apparent when operating with a betatron tune very near the integer (as required for polarization preservation during acceleration in the AGS) and with the lattice chromaticity sextupoles powered. The measurements indicate a small (on the order of millimeters) unexpected systematic horizontal closed orbit displacement in the sextupoles that is not evident in beam position monitor measurements. Motivated especially by these observations a complete survey of the AGS was performed during the 2010 shutdown period.&nb sp; The results of that survey and their impact on the observed optical errors in the AGS are included.

WEP030

Direct Focusing Error Correction with Ring-wide TBT Beam Position Data

quadrupole, lattice, focusing, simulation

1546

M.-J. Yang
Fermilab, Batavia, USA

Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in studying machine optics. Hundreds and thousands of turns of data are taken in just few tens of milliseconds. With beam in free oscillation and covering all positions and angles at every location focusing error diagnosis can be made almost instantly. This paper describes a new approach that observes focusing error collectively over all available TBT data to find the optimized quadrupole strength, one location at a time. Example will be shown and other issues will be discussed.

WEP062

Optimized Sextupole Configurations for Sextupole Magnet Failure in Top-up Operation at the APS*

injection, lattice, power-supply, dynamic-aperture

1588

V. Sajaev
ANL, Argonne, USA

Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Recently there was a situation at the APS when one sextupole power supply failed during top-up operation (all magnets at the APS have separate power supplies). The beam was not lost but the lifetime decreased significantly to the point where it was hard for the injectors to provide enough charge for top-up injections. Luckily, the power supply was able to reset quickly, and the operation was not compromised. One can anticipate similar failures in the future when it would not be possible to reset the power supply. In such a case, the APS would need to operate with lower lifetime until the next intervention period. Here we present an optimization of the sextupole distribution in the vicinity of the failed sextupole that allows us to partially recover the lifetime. A genetic optimization algorithm that involves simultaneous optimization of the dynamic and energy apertures was used*. Experimental tests are also presented.
* M. Borland et al., "Application of Direct Methods of Optimizing Storage Ring Dynamic and Momentum Apertures," Proc. ICAP2009, to be published.

WEP063

Tracking Particles Through A General Magnetic Field

lattice, storage-ring, photon, HOM

1591

A. Xiao, M. Borland, L. Emery, Y. Wang
ANL, Argonne, USA

Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A method that tracks particles directly through a general magnetic field described in a 3D field table was added to the code elegant recently. It was realized by converting an arbitrary particle's motion to a combination of free-drift motion and centripetal motion through the coordinate system rotation and using a general linear interpolation tool developed at the Advanced Photon Source (APS). This method has been tested by tracking particles through conventional magnetic elements (dipole, sextupole, etc.) to verify reference coordinate system conversions, tracking accuracy, and long-term tracking stability. Results show a very good agreement between this new method and the traditional method. This method is not designed to replace mature traditional methods that have been used in most tracking codes. Rather, it is useful for magnets with complicated field profiles or for studying edge effects.

WEP065

Multiobjective Dynamic Aperture Optimization at NSLS-II

lattice, quadrupole, dipole, damping

1597

L. Yang, W. Guo, S. Krinsky, Y. Li
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In this paper we present a multiobjective approach to the dynamic aperture (DA) optimization. Taking the NSLS- II lattice as an example, we have used both sextupoles and quadrupoles as tuning variables to optimize both on-momentum and off-momentum DA. The geometric and chromatic sextupoles are used for nonlinear properties while the tunes are independently varied by quadrupoles. The dispersion and emittance are fixed during tunes variation. The algorithms, procedures, performances and results of our optimization of DA will be discussed and they are found to be robust, general and easy to apply to similar problems.

WEP087

Numerical Studies of Non-Linear Dynamics in BEP

resonance, positron, coupling, booster

1636

I. Koop, E. Perevedentsev
BINP SB RAS, Novosibirsk, Russia
T.V. Zolkin
University of Chicago, Chicago, Illinois, USA

An analysis of the dependence of experimental captured positron current data from the booster storage ring BEP (VEPP-2000 facility, BINP, Russia) on the working point position on the frequency map has uncovered a great number of different non-linear resonances. The number of captured positrons after a single injection is observed to be much less than the expected value. It is anticipated that the high degree of symmetry in the magnet system of BEP, however, should lead to the suppression of such resonances. To study this discrepancy, numerical simulations of positron beam movement under different perturbations to account for potential errors in magnetic field gradient of non-linear elements and errors in their angular location are used. The findings of this research provide qualitative explanations of the experimental work diagram and answers to two main questions, specifically “Why in the absence of skew-sextupoles in structure and small coupling are strong skew-sextupole resonances observed” and “Why skew-sextupole resonances are stronger than sextupole ones of the same harmonic”. A comparison between simulation results and analytical estimates is also presented.

WEP092

Space Charge Effect of the High Intensity Proton Beam during the Resonance Extraction for the MU2E Experiment at Fermilab

space-charge, extraction, septum, resonance

1645

C.S. Park, J.F. Amundson, J.A. Johnstone, V.P. Nagaslaev, S.J. Werkema
Fermilab, Batavia, USA

The proposed Mu2e experiment to search for direct μ to e conversion at Fermilab plans slow, resonant extraction of a beam with 3× 10¹² protons from the Debuncher ring. Space charge of this high intensity beam is a critical factor, since it induces significant betatron tune spread and consequently affects resonance extraction processes, such as spill uniformity and beam losses. This study shows the multi-particle simulation results in the early stages of resonance extraction and spill uniformity in the presence of 2D and 3D space charge effects.

THP059

Chromatic Analysis and Possible Local Chromatic Correction in RHIC

lattice, quadrupole, resonance, betatron

2235

Y. Luo, W. Fischer, X. Gu, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In this article we will answer the following questions: 1) what is the source of second order chromaticities in RHIC? 2) what is the dependence of second order chromaticity on the on-momentum β-beat? 3) what is the dependence of second order chromaticity on β* at IP6 and IP8? To answer these questions, we use the perturbation theory to numerically calculate the contributions of each quadrupole and sextupole to the first, second, and third order chromaticities. Possible methods to locally reduce chromatic effects in RHIC rings are shortly discussed.

THP061

Mimicking Bipolar Sextupole Power Supplies for Low-energy Operations at RHIC

dipole, ion, luminosity, background

2241

C. Montag, D. Bruno, A.K. Jain, G. Robert-Demolaize, T. Satogata, S. Tepikian
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
RHIC operated at energies below the nominal ion injection energy of E=9.8 GeV/u in 2010. Earlier test runs and magnet measurements indicated that all defocusing sextupole unipolar power supplies should be reversed to provide the proper sign of chromaticity. However, vertical chromaticity at E=3.85 GeV/u with this power supply configuration was still not optimal. This uncertainty inspired a new machine configuration where only half of the defocusing sextupole power supplies were reversed, taking advantage of the flexibility of the RHIC nonlinear chromaticity correction system to mimic bipolar sextupoles. This configuration resulted in a 30 percent luminosity gain and eliminated the need for further polarity changes for later 2010 low energy physics operations. Here we describe the background to this problem, operational experience, and RHIC online model changes to implement this solution.

THP065

Advances in High-Order Interaction Region Nonlinear Optics Correction at RHIC

octupole, coupling, collider, interaction-region

2252

C.M. Zimmer, S. Binello, M.G. Minty, F.C. Pilat
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A method to indirectly measure and deterministically correct the higher order magnetic errors of the final focusing magnets in the Relativistic Heavy Ion Collider has been in place for several years at BNL. This method yields control over the effects of multi-pole errors through application of closed orbit bumps followed by analysis and correction of the resulting betatron tune shifts using multi-pole correctors. The process has recently been automated in order to provide more efficient and effective corrections. The tune resolution along with the reliability of tune measurements has also been improved significantly due to advances/upgrades in the betatron tune measurement system employed at RHIC (BBQ). Here we describe the foundation of the IR bump method, followed by recent improvements along with experimental data.

THP071

Interaction Region Design of Super-CT-Factory in Novosibirsk

quadrupole, interaction-region, factory, solenoid

2264

A.V. Bogomyagkov, E.B. Levichev, P.A. Piminov
BINP SB RAS, Novosibirsk, Russia

The interaction region of the Super-CT-factory is designed to bring stored electron-positron beams into collision with luminosity of 10³⁵ cm^-2sec^-1. To achieve this a waist collision scheme is implemented, which requires cross-angle collision with high Piwinski angle. The small values of the beta functions at the interaction point and distant final focus lenses are the reasons for high nonlinear chromaticity limiting energy acceptance of the whole ring. The present design allows correction of linear and nonlinear chromaticity of beta functions and of betatron tune advances, correction of second and third order geometrical aberrations from the strong sextupoles pairs, satisfies geometrical constraints, embraces realistic design of final focus quadrupoles and as close as possible positioning of crab sextupole to interaction point.

THP105

Final Design of ILC RTML Extraction Line for Single Stage Bunch Compressor

extraction, kicker, septum, damping

2321

S. Seletskiy
BNL, Upton, Long Island, New York, USA
N. Solyak
Fermilab, Batavia, USA

The use of single stage bunch compressor (BC) in the International Linear Collider (ILC) [1] 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 the final 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.

THP119

Potential Two-fold Reduction of Advanced Photon Source Emittance using Orbit Displacement

lattice, emittance, quadrupole, damping

2339

M. Borland
ANL, Argonne, USA

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 Advanced Photon Source (APS) is a 7-GeV electron storage ring light source that operates with an effective emittance of 3.1 nm using optics with distributed dispersion. Lower emittance is desirable for some x-ray experiments, but is difficult using conventional optics adjustments because of the required strength of quadrupoles and sextupoles. Changing the damping partition number by changing the rf frequency is another approach, but is incompatible with distributed dispersion because it would require simultaneous realignment of all APS beamlines. In this paper, we evaluate a new approach to changing the damping partition number using a systematic orbit bump in all sectors.

THP125

Multi-objective Optimization of a Lattice for Potential Upgrade of the Advanced Photon Source*

lattice, optics, dynamic-aperture, quadrupole

2354

V. Sajaev, M. Borland, L. Emery, A. Xiao
ANL, Argonne, USA

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 Advanced Photon Source (APS) is a 7-GeV storage ring light source that has been in operation for over a decade. In the near future, the ring may be upgraded, including changes to the lattice such as provision of several long straight sections (LSSs). Use of deflecting cavities for generation of short x-ray pulses is also considered. Because APS beamlines are nearly fully built out, we have limited freedom to place LSSs in a symmetric fashion. Arbitrarily placed LSSs will drastically reduce the symmetry of the optics and would typically be considered unworkable. We apply a recently developed multi-objective direct optimization technique that relies on particle tracking to compute the dynamic aperture and Touschek lifetime. We show that this technique is able to tune sextupole strengths and select the working point in such a way as to recover the dynamic and momentum acceptances. We also show the results of experimental tests of lattices developed using these techniques.

THP189

Low Horizontal Beta Function in Long Straights of the NSLS-II Lattice

lattice, injection, dynamic-aperture, insertion

2471

F. Lin, J. Bengtsson, W. Guo, S. Krinsky, Y. Li, L. Yang
BNL, Upton, New York, USA

Funding: Work supported by U.S. DOE, Contract No. DE-AC02-98CH10886
The NSLS-II storage ring lattice is comprised of 30 DBA cells arranged in 15 superperiods. There are 15 long straight sections (9.3m) for injection, RF and insertion devices and 15 shorter straights (6.6m) for insertion devices. In the baseline lattice, the short straights have small horizontal and vertical beta functions but the long straights have large horizontal beta function optimized for injection. In this note, we explore the possibility of maintaining three long straights with large horizontal beta function while providing the other 12 long straights with smaller horizontal beta function to optimize the brightness of insertion devices. Our study considers the possible linear lattice solutions as well as characterizing the nonlinear dynamics. Results are reported on optimizations of dynamic aperture required for good injection efficiency and adequate Touschek lifetime.

THP214

Pulsed Multipole Injection for the MAX IV Storage Rings

injection, storage-ring, multipole, septum

2522

S.C. Leemann
MAX-lab, Lund, Sweden

The MAX IV facility presently under construction will include two storage rings for the production of synchrotron radiation. The 3 GeV ring will house insertion devices for the production for x-rays while the 1.5 GeV ring will serve UV and IR users. Both rings will be operated at a constant 500 mA of stored current with top-up shots supplied by the 3.5 GeV MAX IV linac acting as a full-energy injector. So far, injection into both storage rings has been designed using a conventional approach: a closed four-kicker injection bump brings the stored beam to the septum blade where the injected bunches are captured in a single turn. Recently, studies have been carried out to investigate the feasibility of using a pulsed multipole for injection into the storage rings. Pulsed multipole injection does not require an injection bump and has the potential to make top-up injection transparent to users. This paper reports on these studies and summarizes requirements for the pulsed sextupole magnet to be installed for injection into the MAX IV storage rings.