IPAC2011 - List of Keywords (dynamic-aperture)

Paper	Title	Other Keywords	Page
MOPS003	Coherent Beam-beam Resonances in SuperB with Asymmetric Rings	resonance, luminosity, simulation, collider	592
	M. Zobov INFN/LNF, Frascati (Roma), Italy Y. Zhang IHEP Beijing, Beijing, People's Republic of China
	One of the latest options of SuperB foresees exploiting rings with unequal circumferences. In such a configuration additional coherent beam-beam resonances can arise. In this paper we discuss the possible impact of the resonances on beam dynamics in SuperB, maximum achievable tune shifts and working point choice.

TUOAB01	Lattice Design of a Very Low-emittance Storage Ring for SPring-8-II	lattice, emittance, alignment, resonance	942
	Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	The design work for an upgrade project of the SPring-8, the SPring-8-II, is in progress. Its ultimate goal is to provide a superior brilliance of photons by reducing emittance of electrons until a diffraction limit. A multi-bend lattice has been adopted for the emittance reduction; a double-bend lattice (natural emittance of 2000 pmrad at 6 GeV), a triple-bend lattice (400 pmrad) and a quadruple-bend lattice (170 pmrad) were designed step by step for studying its feasibility. For an additional emittance reduction, beam dynamic issues for a sextuple-bend lattice have been examined for the first candidate. In this case, the natural emittance is about 70 pmrad. The dynamic aperture has been enlarged by studying beam dynamic phenomena caused by nonlinear dispersion, nonlinear chromaticity, nonlinear resonance, etc., and by optimizing linear and nonlinear optics. The lattice design for the coming upgrade of SPring-8 will be presented in detail. K. Soutome et al., "Design Study of a very Low-emittance Storage Ring for the Future Upgrade Plan of SPring-8", Proc. of IPAC10, WEPEA032, p. 2555 (2010).
	Slides TUOAB01 [4.812 MB]

TUOAB03	Enlarging Dynamic and Momentum Aperture by Particle Swarm Optimization	lattice, sextupole, storage-ring, simulation	948
	Z. Bai, W. Li, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Particle swarm optimization (PSO) is a computational intelligence algorithm for global optimization. Obtaining adequate dynamic and momentum aperture is crucial for high injection efficiency and long beam lifetime in low emittance electron storage rings. Different from nonlinear driving terms optimization, we have made direct optimization of dynamic and momentum aperture by PSO algorithm. It is critical to make a criterion for comparison of dynamic and momentum aperture tracking results in the direct optimization procedure. Thus, in this paper we first propose a quantitative criterion of dynamic aperture. Then we apply PSO to the optimization of chromatic and harmonic sextupoles to find the optimum sextupole settings for enlarging the dynamic aperture. Taking the momentum aperture into consideration, we make joint optimization of dynamic and momentum aperture. Also, the momentum aperture has its quantitative criterion. As an example of application, the dynamic and momentum aperture of an FBA lattice studied in the design of storage ring of Hefei Advanced Light Source were optimized, and the results have shown the power of PSO algorithm.
	Slides TUOAB03 [0.313 MB]

TUPZ023	Observation of Bunch to Bunch Differences due to Beam-beam Effects	luminosity, injection, emittance, kicker	1855
	G. Papotti, R. Alemany-Fernandez, R. Giachino, W. Herr, T. Pieloni, M. Schaumann, G. Trad CERN, Geneva, Switzerland
	Due to the bunch filling schemes in the LHC the bunches experience a very different collision schedule and therefore different beam-beam effects. These differences and the effect on the performance have been observed and compared with the expectations. Possible limitations due to these effects are discussed.

TUPZ037	Momentum Aperture for the Low Beta* Lattices in RHIC Au-Au Runs	lattice, heavy-ion, ion, beam-losses	1891
	Y. Luo, K.A. Brown, W. Fischer, X. Gu, G. Robert-Demolaize, T. Roser, V. Schoefer, S. Tepikian, 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 calculate the momentum apertures with the low beta* lattices of 100 GeV RHIC Au-Au run. With RF re-bucketing, the maximum off-momentum spread reaches 1.7 ·10^-03 at store. To improve the momentum aperture, we need to reduce the nonlinear chromaticities. The methods to correct second order chromaticities in RHIC rings are presented. We also scan beta* at IP6 and IP8 and working point. The challenges to further reduce beta* in the RHIC Au-Au operation are discussed.

WEODA01	Observations of Beam-beam Effects at High Intensities in the LHC	luminosity, emittance, beam-beam-effects, brightness	1936
	W. Herr, R. Alemany-Fernandez, R. Giachino, G. Papotti, T. Pieloni CERN, Geneva, Switzerland R. Calaga BNL, Upton, Long Island, New York, USA E. Laface ESS, Lund, Sweden M. Schaumann RWTH, Aachen, Germany
	First observations with colliding beams in the LHC with bunch intensities close to nominal and above are reported. In 2010 the LHC initially operated with few bunches spaced around the circumference. Beam-beam tune shifts exceeding significantly the design value have been observed. In a later stage crossing angles were introduced around the experiments to allow the collisions of bunch trains. We report the first experience with head-on as well as long range interactions of high intensity bunches and discuss the possible performance reach.
	Slides WEODA01 [0.409 MB]

WEPC035	Double Mini-Betay Lattice for TPS Storage Ring	lattice, emittance, multipole, quadrupole	2082
	M.-S. Chiu, H.-P. Chang, C.-T. Chen, C.C. Chiang, C.-C. Kuo, Y.C. Lee, H.-J. Tsai, C.H. Yang NSRRC, Hsinchu, Taiwan
	Based on our previous design of double mini-betay optics in one 12-m straight section, NSRRC plan to implement the double mini-betay lattice in three 12-m straight sections in TPS storage ring. Those three locations chosen for double mini-betay lattice still retain the symmetry of accelerator lattice. The two symmetric minima of the vertical beta function will be created in the center of three 12-m straight sections, respectively. We strived to obtain a linear lattice such that there is no significant increase in the natural emittance. Efforts were devoted to optimize the nonlinear beam dynamics with various simulation tools. Preliminary results will be reported.

WEPC057	Estimation of the Dynamic Aperture by Transverse Beam Excitation with Noise Close to a Resonance	lattice, resonance, beam-losses, sextupole	2145
	S. Sorge, G. Franchetti GSI, Darmstadt, Germany
	The present heavy ion synchrotron SIS-18 will be upgraded to be used as a booster for further synchrotrons being part of the FAIR project underway at GSI. Recently, a method was developed to measure the physical aperture of SIS-18 using transverse RF noise. This method is based on the transverse expansion of the beam with noise beyond the limiting aperture generating beam loss. The aperture was determined from the comparison of the resulting time evolution of the beam current in the machine with that obtained from a numerical simulation. In this study we attempt to apply this method to determine the dynamic aperture of SIS-18.

WEPC080	Non-linear Dynamics Optimization of the CLIC Damping Rings	resonance, emittance, lattice, quadrupole	2205
	Y. Renier, F. Antoniou, H. Bartosik, Y. Papaphilippou CERN, Geneva, Switzerland K.P. Wootton The University of Melbourne, Melbourne, Australia
	Non-linear dynamics studies are undertaken in order to optimize the dynamic aperture of the CLIC damping rings. In this respect, advanced methods such as frequency map and resonance driving term analysis are used in order to explore the working point space with respect to single particle stability. The impact of magnet errors and misalignments, and in particular, the effect of the super-conducting damping wigglers is evaluated. Additional considerations for the working point choice are presented.

WEPC104	Vicky : A Computer Code for Use in the Design and Simulation of Particle Accelerators	sextupole, kicker, quadrupole, closed-orbit	2256
	F. Iazzourene ELETTRA, Basovizza, Italy
	Vicky is a computer code under development for designing and simulating particle accelerators. Like other existing codes, the features include machine imperfections, closed orbit correction, Twiss functions matching, chromaticity evaluation and correction, particle tracking and so on. The goal is to give the users a friendly graphical interface with widgets to perform the wished tasks, for example to plot the orbit, the Twiss functions, the tune diagram, the dynamic aperture and so on, to select and read an input file describing the considered lattice, to perform the Twiss functions matching, a closed orbit correction and so on. The code provides a description of the particle motion by 10 parameters: four beta-functions, four alpha-functions and two phase advances, that is a 4*4 generalized transverse coupling, together with an emphasis on the treatment of the complex 3D magnetic fields of the undulators used in today’s modern synchrotron radiation facilities. The code is written in C++. It uses the free packages QT for the online plots and the graphical user interface and IT++ for the mathematics. The present status and some results of its application will be presented.

WEPC162	Investigations into Non-linear Beam Dynamics in Electrostatic Storage Rings	lattice, quadrupole, focusing, proton	2361
	D. Newton, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom O.E. Gorda MPI-K, Heidelberg, Germany D. Newton The University of Liverpool, Liverpool, United Kingdom A.I. Papash JINR, Dubna, Moscow Region, Russia
	Funding: Work supported by STFC, the Helmholtz Association and GSI under contract VH-NG-328. Electrostatic (ES) storage rings provide a cost-effective solution to the problem of confining low energy (beta << 1) charged particles and ions, whilst controlling the beam properties, for use in multi-pass experiments. However, compared to magnetic storage rings, the beam dynamics calculations for an ES ring show subtle differences, especially in the coupling of the longitudinal and transverse velocities and in the focusing properties of bending element fringe fields. Using the nominal design for a prototype ES ring, realistic trajectories (including fringe fields and non-linear field components) have been calculated and a comparison is made with linear lattice simulations. The effect of the non-linear field components on the beam parameters is discussed.

WEPS001	A New Lattice for the Beta-beam Decay Ring to Reduce the Head Tail Effects	injection, lattice, dipole, ion	2478
	A. Chancé, J. Payet CEA/DSM/IRFU, France C. Hansen CERN, Geneva, Switzerland
	Funding: I acknowledge the financial support of the European Community under the European Commission Framework Programme 7 Design Study: EUROnu, Project Number 212372. The beta-beam concept relies on the production, by beta decay of radioactive ions of a very high flux, of an electron neutrino and anti-neutrino beam towards a distant detector. In this aim, the radioactive isotopes are stored in a long racetrack-shaped ring, called the decay ring, where they orbit until they decay or are lost. The intensities to store in the decay ring to obtain the required neutrino fluxes are very high (several amperes in average). Therefore, collective effects occur. Among them, the head tail effect, caused by transversal resonance impedance, is one of the main issues: the beam was shown to be unstable with the previous decay ring lattice. The transition gamma was reduced to mitigate this problem. For this purpose the lattice was changed by removing the injection from the arc to put it in a chicane which is added in one of the long straight sections. After presenting the limitation due to head tail effects, we will present the modification in the lattice and their impact on the dynamic aperture in the decay ring. Then the improvement on the beta-beam performance with respect to the lower transition gamma will be shown.

WEPS087	Dynamics of a Novel Isochronous Non-scaling FFAG	lattice, acceleration, closed-orbit, simulation	2712
	S.L. Sheehy STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	Many non-scaling FFAG accelerator designs involve magnetic fields that cannot be described in popular accelerator design codes, and complex beam dynamics that require extremely accurate simulations. A recent design of a 1 GeV isochronous non-scaling FFAG is used to compare the codes COSY Infinity and ZGOUBI, both of which are commonly used in FFAG design. Results are presented for the comparison of basic beam dynamics and calculated dynamic aperture.

THPC064	Design Study of Low Emittance Lattice for Taiwan Light Source at 1 GeV	emittance, lattice, storage-ring, wiggler	3041
	C.Y. Lee NTHU, Hsinchu, Taiwan C.C. Chiang, P.J. Chou NSRRC, Hsinchu, Taiwan S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	We explored the possibility that the existing TLS storage ring to be operated at 1 GeV as a high brightness VUV light source after the completion of 3 GeV Taiwan Photon Source. To increase the spectral brightness, we need to reduce the beam emittance in the storage ring as much as possible. We first pursue the lowest emittance which is possible without altering the existing hardware configuration. The theoretical minimum emittance that could be achieved at 1 GeV for non-achromatic lattice is 3.8 nm-rad. However, this could not be achieved without introducing harmonic sextupoles. Preliminary results of low emittance lattice without harmonic sextupoles in TLS storage ring will be presented.

THPC073	Study of Lower Emittance Lattices for SPEAR3	lattice, emittance, sextupole, injection	3062
	X. Huang, Y. Nosochkov, J.A. Safranek, L. Wang SLAC, Menlo Park, California, USA
	We study paths to significantly reduce the emittance of the SPEAR3 storage ring. Lattice possibilities are explored with the GLASS technique. New lattices are designed and optimized for practical dynamic aperture and beam lifetime. Various techniques are employed to optimize the nonlinear dynamics, including the Elegant-based genetic algorithm. Experimental studies are also carried out on the ring to validate the lattice design.

THPC074	Dynamic Aperture and Tolerances for PEP-X Ultimate Storage Ring Design	sextupole, resonance, quadrupole, coupling	3065
	M.-H. Wang, Y. Cai, R.O. Hettel, Y. Nosochkov SLAC, Menlo Park, California, USA M. Borland ANL, Argonne, USA
	Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. A lattice for the PEP-X ultimate storage ring light source[1], having 11 pm-rad natural emittance at a beam energy of 4.5 GeV at zero current, using 90 m of damping wiggler and fitting into the existing 2.2-km PEP-II tunnel, has been recently designed[2]. Such a low emittance lattice requires very strong sextupoles for chromaticity correction, which in turn introduce strong non-linear field effects that limit the beam dynamic aperture. In order to maximize the dynamic aperture we choose the cell phases to cancel the third and fourth order geometric resonances in each 8-cell arc. Four families of chromatic sextupoles and six families of geometric (or harmonic) sextupoles are added to correct the chromatic and amplitude-dependent tunes. To find the best settings of the ten sextupole families, we use a Multi-Objective Genetic Optimizer employing elegant[3] to optimize the beam lifetime and dynamic aperture simultaneously. Then we evaluate dynamic aperture reduction caused by magnetic field multipole errors, magnet fabrication errors and misalignments. A sufficient dynamic aperture is obtained for injection, as well as workable beam lifetime[2].

THPC075	Lattice Design for PEP-X Ultimate Storage Ring Light Source	emittance, wiggler, lattice, dipole	3068
	Y. Nosochkov, K.L.F. Bane, Y. Cai, R.O. Hettel, M.-H. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source – PEP-X – that would replace the SPEAR3 storage ring in the future. The "baseline" design for PEP-X, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step in the study, a so-called "ultimate" PEP-X lattice having another order of magnitude reduction in emittance from the baseline design has been investigated. The beam emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. In this design, the ring arcs contain seven-bend achromat cells yielding 29 pm-rad natural emittance and up to 9 insertion device straights per arc. Another factor of two emittance reduction is achieved with an 89.3-m damping wiggler installed in one of the six long straights. Details of the lattice design, the sextupole correction scheme, dynamic aperture simulations, and calculation of the intra-beam scattering effect and Touschek lifetime at a nominal 200-mA current are presented.

THPZ007	Lattice Design of Low Emittance and Low Beta Function at Collision Point for SuperKEKB	emittance, dipole, luminosity, lattice	3693
	Y. Ohnishi, H. Koiso, A. Morita, K. Oide, H. Sugimoto KEK, Ibaraki, Japan
	Extremely low beta function at the interaction point(IP) and low emittance are necessary to achieve the design luminosity of 8x10³5 cm^-2 s^-1 for a SuperKEKB project. The low emittance with a large Piwinski angle makes this possible with longer bunch longitudinally compared with the vertical beta function at IP. We call this Nano-beam scheme. In this scheme, a beam-beam parameter is realized to be less than 0.09 for the design luminosity. The lattice features, chromaticity corrections, and dynamic aperture are discussed in this article.

THPZ011	Optimization of Chromatic Sextupoles in Electron Storage Rings Using Genetic Algorithms	sextupole, storage-ring, resonance, emittance	3705
	Z. Duan IHEP Beijng, Beijing, People's Republic of China Q. Qin IHEP Beijing, Beijing, People's Republic of China
	Funding: Work supported by National Science Foundation of China contract 10725525. In order to suppress the head-tail instability, strong chromatic sextupoles are used in modern electron storage rings to correct large chromaticities due to small emittance or strong insertion quadrupoles to squeeze the bunch size at some places. However, the introduction of strong chromatic sextupoles also brings severe nonlinearity and might reduce dynamic aperture drastically. In the case of several sextupole families, the genetic algorithms are applied to find suitable configurations of sextupole strengths, directly maximizing dynamic aperture. A GeneRepair operator is introduced into the algorithm to correct chromaticities and optimize the dynamic aperture simultaneously in electron storage rings.

THPZ013	A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities	cavity, optics, insertion, luminosity	3711
	R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland
	The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme. S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings.

Paper

Title

Other Keywords

Page

MOPS003

Coherent Beam-beam Resonances in SuperB with Asymmetric Rings

resonance, luminosity, simulation, collider

592

M. Zobov
INFN/LNF, Frascati (Roma), Italy
Y. Zhang
IHEP Beijing, Beijing, People's Republic of China

One of the latest options of SuperB foresees exploiting rings with unequal circumferences. In such a configuration additional coherent beam-beam resonances can arise. In this paper we discuss the possible impact of the resonances on beam dynamics in SuperB, maximum achievable tune shifts and working point choice.

TUOAB01

Lattice Design of a Very Low-emittance Storage Ring for SPring-8-II

lattice, emittance, alignment, resonance

942

Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

The design work for an upgrade project of the SPring-8, the SPring-8-II, is in progress. Its ultimate goal is to provide a superior brilliance of photons by reducing emittance of electrons until a diffraction limit. A multi-bend lattice has been adopted for the emittance reduction; a double-bend lattice (natural emittance of 2000 pmrad at 6 GeV), a triple-bend lattice (400 pmrad) and a quadruple-bend lattice (170 pmrad) were designed step by step for studying its feasibility*. For an additional emittance reduction, beam dynamic issues for a sextuple-bend lattice have been examined for the first candidate. In this case, the natural emittance is about 70 pmrad. The dynamic aperture has been enlarged by studying beam dynamic phenomena caused by nonlinear dispersion, nonlinear chromaticity, nonlinear resonance, etc., and by optimizing linear and nonlinear optics. The lattice design for the coming upgrade of SPring-8 will be presented in detail.
* K. Soutome et al., "Design Study of a very Low-emittance Storage Ring for the Future Upgrade Plan of SPring-8", Proc. of IPAC10, WEPEA032, p. 2555 (2010).

Slides TUOAB01 [4.812 MB]

TUOAB03

Enlarging Dynamic and Momentum Aperture by Particle Swarm Optimization

lattice, sextupole, storage-ring, simulation

948

Z. Bai, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Particle swarm optimization (PSO) is a computational intelligence algorithm for global optimization. Obtaining adequate dynamic and momentum aperture is crucial for high injection efficiency and long beam lifetime in low emittance electron storage rings. Different from nonlinear driving terms optimization, we have made direct optimization of dynamic and momentum aperture by PSO algorithm. It is critical to make a criterion for comparison of dynamic and momentum aperture tracking results in the direct optimization procedure. Thus, in this paper we first propose a quantitative criterion of dynamic aperture. Then we apply PSO to the optimization of chromatic and harmonic sextupoles to find the optimum sextupole settings for enlarging the dynamic aperture. Taking the momentum aperture into consideration, we make joint optimization of dynamic and momentum aperture. Also, the momentum aperture has its quantitative criterion. As an example of application, the dynamic and momentum aperture of an FBA lattice studied in the design of storage ring of Hefei Advanced Light Source were optimized, and the results have shown the power of PSO algorithm.

Slides TUOAB03 [0.313 MB]

TUPZ023

Observation of Bunch to Bunch Differences due to Beam-beam Effects

luminosity, injection, emittance, kicker

1855

G. Papotti, R. Alemany-Fernandez, R. Giachino, W. Herr, T. Pieloni, M. Schaumann, G. Trad
CERN, Geneva, Switzerland

Due to the bunch filling schemes in the LHC the bunches experience a very different collision schedule and therefore different beam-beam effects. These differences and the effect on the performance have been observed and compared with the expectations. Possible limitations due to these effects are discussed.

TUPZ037

Momentum Aperture for the Low Beta* Lattices in RHIC Au-Au Runs

lattice, heavy-ion, ion, beam-losses

1891

Y. Luo, K.A. Brown, W. Fischer, X. Gu, G. Robert-Demolaize, T. Roser, V. Schoefer, S. Tepikian, 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 calculate the momentum apertures with the low beta* lattices of 100 GeV RHIC Au-Au run. With RF re-bucketing, the maximum off-momentum spread reaches 1.7 ·10^-03 at store. To improve the momentum aperture, we need to reduce the nonlinear chromaticities. The methods to correct second order chromaticities in RHIC rings are presented. We also scan beta* at IP6 and IP8 and working point. The challenges to further reduce beta* in the RHIC Au-Au operation are discussed.

WEODA01

Observations of Beam-beam Effects at High Intensities in the LHC

luminosity, emittance, beam-beam-effects, brightness

1936

W. Herr, R. Alemany-Fernandez, R. Giachino, G. Papotti, T. Pieloni
CERN, Geneva, Switzerland
R. Calaga
BNL, Upton, Long Island, New York, USA
E. Laface
ESS, Lund, Sweden
M. Schaumann
RWTH, Aachen, Germany

First observations with colliding beams in the LHC with bunch intensities close to nominal and above are reported. In 2010 the LHC initially operated with few bunches spaced around the circumference. Beam-beam tune shifts exceeding significantly the design value have been observed. In a later stage crossing angles were introduced around the experiments to allow the collisions of bunch trains. We report the first experience with head-on as well as long range interactions of high intensity bunches and discuss the possible performance reach.

Slides WEODA01 [0.409 MB]

WEPC035

Double Mini-Betay Lattice for TPS Storage Ring

lattice, emittance, multipole, quadrupole

2082

M.-S. Chiu, H.-P. Chang, C.-T. Chen, C.C. Chiang, C.-C. Kuo, Y.C. Lee, H.-J. Tsai, C.H. Yang
NSRRC, Hsinchu, Taiwan

Based on our previous design of double mini-betay optics in one 12-m straight section, NSRRC plan to implement the double mini-betay lattice in three 12-m straight sections in TPS storage ring. Those three locations chosen for double mini-betay lattice still retain the symmetry of accelerator lattice. The two symmetric minima of the vertical beta function will be created in the center of three 12-m straight sections, respectively. We strived to obtain a linear lattice such that there is no significant increase in the natural emittance. Efforts were devoted to optimize the nonlinear beam dynamics with various simulation tools. Preliminary results will be reported.

WEPC057

Estimation of the Dynamic Aperture by Transverse Beam Excitation with Noise Close to a Resonance

lattice, resonance, beam-losses, sextupole

2145

S. Sorge, G. Franchetti
GSI, Darmstadt, Germany

The present heavy ion synchrotron SIS-18 will be upgraded to be used as a booster for further synchrotrons being part of the FAIR project underway at GSI. Recently, a method was developed to measure the physical aperture of SIS-18 using transverse RF noise. This method is based on the transverse expansion of the beam with noise beyond the limiting aperture generating beam loss. The aperture was determined from the comparison of the resulting time evolution of the beam current in the machine with that obtained from a numerical simulation. In this study we attempt to apply this method to determine the dynamic aperture of SIS-18.

WEPC080

Non-linear Dynamics Optimization of the CLIC Damping Rings

resonance, emittance, lattice, quadrupole

2205

Y. Renier, F. Antoniou, H. Bartosik, Y. Papaphilippou
CERN, Geneva, Switzerland
K.P. Wootton
The University of Melbourne, Melbourne, Australia

Non-linear dynamics studies are undertaken in order to optimize the dynamic aperture of the CLIC damping rings. In this respect, advanced methods such as frequency map and resonance driving term analysis are used in order to explore the working point space with respect to single particle stability. The impact of magnet errors and misalignments, and in particular, the effect of the super-conducting damping wigglers is evaluated. Additional considerations for the working point choice are presented.

WEPC104

Vicky : A Computer Code for Use in the Design and Simulation of Particle Accelerators

sextupole, kicker, quadrupole, closed-orbit

2256

F. Iazzourene
ELETTRA, Basovizza, Italy

Vicky is a computer code under development for designing and simulating particle accelerators. Like other existing codes, the features include machine imperfections, closed orbit correction, Twiss functions matching, chromaticity evaluation and correction, particle tracking and so on. The goal is to give the users a friendly graphical interface with widgets to perform the wished tasks, for example to plot the orbit, the Twiss functions, the tune diagram, the dynamic aperture and so on, to select and read an input file describing the considered lattice, to perform the Twiss functions matching, a closed orbit correction and so on. The code provides a description of the particle motion by 10 parameters: four beta-functions, four alpha-functions and two phase advances, that is a 4*4 generalized transverse coupling, together with an emphasis on the treatment of the complex 3D magnetic fields of the undulators used in today’s modern synchrotron radiation facilities. The code is written in C++. It uses the free packages QT for the online plots and the graphical user interface and IT++ for the mathematics. The present status and some results of its application will be presented.

WEPC162

Investigations into Non-linear Beam Dynamics in Electrostatic Storage Rings

lattice, quadrupole, focusing, proton

2361

D. Newton, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
O.E. Gorda
MPI-K, Heidelberg, Germany
D. Newton
The University of Liverpool, Liverpool, United Kingdom
A.I. Papash
JINR, Dubna, Moscow Region, Russia

Funding: Work supported by STFC, the Helmholtz Association and GSI under contract VH-NG-328.
Electrostatic (ES) storage rings provide a cost-effective solution to the problem of confining low energy (beta << 1) charged particles and ions, whilst controlling the beam properties, for use in multi-pass experiments. However, compared to magnetic storage rings, the beam dynamics calculations for an ES ring show subtle differences, especially in the coupling of the longitudinal and transverse velocities and in the focusing properties of bending element fringe fields. Using the nominal design for a prototype ES ring, realistic trajectories (including fringe fields and non-linear field components) have been calculated and a comparison is made with linear lattice simulations. The effect of the non-linear field components on the beam parameters is discussed.

WEPS001

A New Lattice for the Beta-beam Decay Ring to Reduce the Head Tail Effects

injection, lattice, dipole, ion

2478

A. Chancé, J. Payet
CEA/DSM/IRFU, France
C. Hansen
CERN, Geneva, Switzerland

Funding: I acknowledge the financial support of the European Community under the European Commission Framework Programme 7 Design Study: EUROnu, Project Number 212372.
The beta-beam concept relies on the production, by beta decay of radioactive ions of a very high flux, of an electron neutrino and anti-neutrino beam towards a distant detector. In this aim, the radioactive isotopes are stored in a long racetrack-shaped ring, called the decay ring, where they orbit until they decay or are lost. The intensities to store in the decay ring to obtain the required neutrino fluxes are very high (several amperes in average). Therefore, collective effects occur. Among them, the head tail effect, caused by transversal resonance impedance, is one of the main issues: the beam was shown to be unstable with the previous decay ring lattice. The transition gamma was reduced to mitigate this problem. For this purpose the lattice was changed by removing the injection from the arc to put it in a chicane which is added in one of the long straight sections. After presenting the limitation due to head tail effects, we will present the modification in the lattice and their impact on the dynamic aperture in the decay ring. Then the improvement on the beta-beam performance with respect to the lower transition gamma will be shown.

WEPS087

Dynamics of a Novel Isochronous Non-scaling FFAG

lattice, acceleration, closed-orbit, simulation

2712

S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Many non-scaling FFAG accelerator designs involve magnetic fields that cannot be described in popular accelerator design codes, and complex beam dynamics that require extremely accurate simulations. A recent design of a 1 GeV isochronous non-scaling FFAG is used to compare the codes COSY Infinity and ZGOUBI, both of which are commonly used in FFAG design. Results are presented for the comparison of basic beam dynamics and calculated dynamic aperture.

THPC064

Design Study of Low Emittance Lattice for Taiwan Light Source at 1 GeV

emittance, lattice, storage-ring, wiggler

3041

C.Y. Lee
NTHU, Hsinchu, Taiwan
C.C. Chiang, P.J. Chou
NSRRC, Hsinchu, Taiwan
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

We explored the possibility that the existing TLS storage ring to be operated at 1 GeV as a high brightness VUV light source after the completion of 3 GeV Taiwan Photon Source. To increase the spectral brightness, we need to reduce the beam emittance in the storage ring as much as possible. We first pursue the lowest emittance which is possible without altering the existing hardware configuration. The theoretical minimum emittance that could be achieved at 1 GeV for non-achromatic lattice is 3.8 nm-rad. However, this could not be achieved without introducing harmonic sextupoles. Preliminary results of low emittance lattice without harmonic sextupoles in TLS storage ring will be presented.

THPC073

Study of Lower Emittance Lattices for SPEAR3

lattice, emittance, sextupole, injection

3062

X. Huang, Y. Nosochkov, J.A. Safranek, L. Wang
SLAC, Menlo Park, California, USA

We study paths to significantly reduce the emittance of the SPEAR3 storage ring. Lattice possibilities are explored with the GLASS technique. New lattices are designed and optimized for practical dynamic aperture and beam lifetime. Various techniques are employed to optimize the nonlinear dynamics, including the Elegant-based genetic algorithm. Experimental studies are also carried out on the ring to validate the lattice design.

THPC074

Dynamic Aperture and Tolerances for PEP-X Ultimate Storage Ring Design

sextupole, resonance, quadrupole, coupling

3065

M.-H. Wang, Y. Cai, R.O. Hettel, Y. Nosochkov
SLAC, Menlo Park, California, USA
M. Borland
ANL, Argonne, USA

Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515.
A lattice for the PEP-X ultimate storage ring light source[1], having 11 pm-rad natural emittance at a beam energy of 4.5 GeV at zero current, using 90 m of damping wiggler and fitting into the existing 2.2-km PEP-II tunnel, has been recently designed[2]. Such a low emittance lattice requires very strong sextupoles for chromaticity correction, which in turn introduce strong non-linear field effects that limit the beam dynamic aperture. In order to maximize the dynamic aperture we choose the cell phases to cancel the third and fourth order geometric resonances in each 8-cell arc. Four families of chromatic sextupoles and six families of geometric (or harmonic) sextupoles are added to correct the chromatic and amplitude-dependent tunes. To find the best settings of the ten sextupole families, we use a Multi-Objective Genetic Optimizer employing elegant[3] to optimize the beam lifetime and dynamic aperture simultaneously. Then we evaluate dynamic aperture reduction caused by magnetic field multipole errors, magnet fabrication errors and misalignments. A sufficient dynamic aperture is obtained for injection, as well as workable beam lifetime[2].

THPC075

Lattice Design for PEP-X Ultimate Storage Ring Light Source

emittance, wiggler, lattice, dipole

3068

Y. Nosochkov, K.L.F. Bane, Y. Cai, R.O. Hettel, M.-H. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515.
SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source – PEP-X – that would replace the SPEAR3 storage ring in the future. The "baseline" design for PEP-X, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step in the study, a so-called "ultimate" PEP-X lattice having another order of magnitude reduction in emittance from the baseline design has been investigated. The beam emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. In this design, the ring arcs contain seven-bend achromat cells yielding 29 pm-rad natural emittance and up to 9 insertion device straights per arc. Another factor of two emittance reduction is achieved with an 89.3-m damping wiggler installed in one of the six long straights. Details of the lattice design, the sextupole correction scheme, dynamic aperture simulations, and calculation of the intra-beam scattering effect and Touschek lifetime at a nominal 200-mA current are presented.

THPZ007

Lattice Design of Low Emittance and Low Beta Function at Collision Point for SuperKEKB

emittance, dipole, luminosity, lattice

3693

Y. Ohnishi, H. Koiso, A. Morita, K. Oide, H. Sugimoto
KEK, Ibaraki, Japan

Extremely low beta function at the interaction point(IP) and low emittance are necessary to achieve the design luminosity of 8x10³5 cm^-2 s^-1 for a SuperKEKB project. The low emittance with a large Piwinski angle makes this possible with longer bunch longitudinally compared with the vertical beta function at IP. We call this Nano-beam scheme. In this scheme, a beam-beam parameter is realized to be less than 0.09 for the design luminosity. The lattice features, chromaticity corrections, and dynamic aperture are discussed in this article.

THPZ011

Optimization of Chromatic Sextupoles in Electron Storage Rings Using Genetic Algorithms

sextupole, storage-ring, resonance, emittance

3705

Z. Duan
IHEP Beijng, Beijing, People's Republic of China
Q. Qin
IHEP Beijing, Beijing, People's Republic of China

Funding: Work supported by National Science Foundation of China contract 10725525.
In order to suppress the head-tail instability, strong chromatic sextupoles are used in modern electron storage rings to correct large chromaticities due to small emittance or strong insertion quadrupoles to squeeze the bunch size at some places. However, the introduction of strong chromatic sextupoles also brings severe nonlinearity and might reduce dynamic aperture drastically. In the case of several sextupole families, the genetic algorithms are applied to find suitable configurations of sextupole strengths, directly maximizing dynamic aperture. A GeneRepair operator is introduced into the algorithm to correct chromaticities and optimize the dynamic aperture simultaneously in electron storage rings.

THPZ013

A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities

cavity, optics, insertion, luminosity

3711

R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme*.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings.