SLAC, Menlo Park, California
UNM, Albuquerque, New Mexico
The goal is to construct a symplectic evolution map for a large section of an accelerator, say a full turn of a large ring or a long wiggler. We start with an accurate tracking algorithm for single particles, which is allowed to be slightly non-symplectic. By tracking many particles for a distance S one acquires sufficient data to construct the mixed-variable generator of a symplectic map for evolution over S. Two ways to find the generator are considered: (i) Find its gradient from tracking data, then the generator itself as a line integral *. (ii) Compute Hamilton's principal function on many orbits. The generator is given finally as an interpolatory C2 function, say through B-splines or Shepard's meshless interpolation. A test of method (i) is given in a hard example: a full turn map for an electron ring with strong sextupoles. The method succeeds where Taylor maps fail, but there are technical difficulties near the dynamic aperture due to oddly shaped interpolation domains. Method (ii) looks more promising in strongly nonlinear cases. We also explore explicit maps from direct fits of tracking data, with symplecticity imposed on local interpolating functions.
BNL, Upton, Long Island, New York
KVI, Groningen
CLASSE, Ithaca, New York
In the proposed electric dipole moment (EDM) experiment, with an estimated spin coherence time of 1000 s, the spin precession due to an EDM of 10-29 e.cm will produce a change in the vertical spin component of approximately 10 μrad during the storage time. Such high sensitivity needs an extremely high accurate and reliable simulation environment of the beam and spin behavior during the storage time. Therefore, several spin-related accelerator programs have been considered and investigated. The paper surveys the computational algorithms of these approaches and provides their comprehensive analysis from multiple perspectives: accuracy, performance, extensibility, and scope of potential applications.
BNL, Upton, Long Island, New York
In the quest for brigthness, the horizontal emittance remains one of the main performance parameters for modern synchrotron light sources. A control theory approach that takes the nonlinear dynamics aspects into account, by a few simple (linear) optics guidelines, at an early stage generates robust designs. Modern analytic- and computational techniques enables the optics designer to avoid the fallacy of the traditional approach guided by the Theoretical Minimum Emittance (TME) cell: the "chromaticity wall". In particular, by an interleaved computational approach with the nonlinear dynamics analyst/model. We also outline how to implement the correction algorithms for a realistic model so that they can be re-used as part of an on-line model/control server for commissioning- and operations of the real system.
ANL, Argonne
BNL, Upton, Long Island, New York
ELEGANT is an open-source accelerator code that has been under development for approximately two decades. In that time, it has evolved from a graduate student project with a narrow purpose to a general code for the design and modeling of linacs and storage rings. ELEGANT continues to evolve, thanks in no small part to suggestions from users. ELEGANT has seen extensive application to modeling of linacs, particularly for applications related to free-electron lasers and energy recovery linacs. Recent developments have emphasized both linac and storage-ring-related enhancements, along with parallelization. In this paper, we briefly review the features of ELEGANT and its program suite. We then describe some of the recent progress made in the ongoing development of ELEGANT. We also discuss several noteworthy applications and directions for future work.
ORNL, Oak Ridge, Tennessee
SLAC, Menlo Park, California
XAL is a Java programming framework for building high-level control applications related to accelerator physics. The core of XAL consists of a GUI framework to provide common “look and feel” and functionality for all XAL applications, a hardware representation of the machine for connectivity and control, and a beam simulation model termed the "online model" for model reference and comparison to the hardware operation. The structure, details of implementation, and interaction between these components, auxiliary XAL packages, and applications are discussed. A general overview of applications created for the SNS project and based on XAL is presented.
BNL, Upton, Long Island, New York
The on-line models for RHIC and the RHIC pre-injectors (the AGS and the AGS Booster) can be thought of as containing our best collective knowledge of these accelerators. As we improve these on-line models we are building the framework to have a sophisticated model-based controls system. Currently the RHIC on-line model is an integral part of the controls system, providing the interface for tune control, chromaticity control, and non-linear chromaticity control. What we will discuss in this paper is our vision of the future of the on-line model environment for RHIC and the RHIC pre-injectors. Although primarily these on-line models are used as Courant-Snyder parameter calculators using live machine settings, we envision expanding these environments to encompass many other problem domains. We will also discuss the importance of the modeling infrastructure and organization as well as interfacing to controls, power supply, and magnetic measurement infrastructure and organizations. The model engines themselves will be discussed and our own evolution toward incorporating more sophisticated simulation filters, such as PTC and UAL, into the on-line model infrastructure.
HU/AdSM, Higashi-Hiroshima
JAEA/Kansai, Kyoto
TUB, Beijing
JAEA/TARRI, Gunma-ken
An ultimate goal in accelerator physics is to produce a "zero-emittance" beam, which is equivalent to making the beam temperature the absolute zero in the center-of-mass frame. At this limit, if somehow reached, the beam is Coulomb crystallized. Schiffer and co-workers first applied the molecular dynamics (MD) technique to study the fundamental features of various Coulomb crystals. Their pioneering work was later generalized by Wei et al. who explicitly incorporated discrete alternating-gradient lattice structures into MD simulations. This talk summarizes recent numerical efforts made to clarify the dynamic behavior of ultra-cold and crystalline ion beams. The MD modeling of beam crystallization in a storage ring is outlined, including how one can approach the ultra-low emittance limit. Several possible methods are described of cooling an ion beam three-dimensionally with radiation pressure (the Doppler laser cooling).
IHEP Beijing, Beijing
The China Spallation Neutron Source (CSNS) is now in the design stage. Many simulations have been done for the RCS/CSNS, including the space charge induced emittance growth and beam loss, the combined effects of space charge and magnet errors, the dependence of space charge effects on the lattice structures, etc.
BNL, Upton, Long Island, New York
LBNL, Berkeley, California
Multiobjective Genetic Algorithm(MOGA) is a technique for optimization, and based on the populations and natural selections. We have integrated this algorithm with linear lattice calculation code to make the lattice design more robust.
ANL, Argonne
BNL, Upton, Long Island, New York
Optimization of dynamic and momentum apertures is one of the most challenging problems in storage ring design. For storage-ring-based x-ray sources, large dynamic aperture is important in obtaining high injection efficiency, which leads to efficient operation and protects components from radiation damage. X-ray sources require large momentum aperture to obtain sufficiently long Touschek lifetimes with low-emittance beams. We have developed effective methods of optimizing dynamic and momentum apertures that rely directly on tracking using a moderately sized Linux cluster. After reviewing the method, we present examples of its application to APS operations, upgrades, and next-generation storage rings.
RadiaBeam, Marina del Rey
UCLA, Los Angeles, California
PSI, Villigen
The development of the code RadTrack is based on the need to model accelerator system diagnostics. The code is built using a modular approach with a strong emphasis on intuitive user interface. The operations of trajectory calculation and radiation field solving are segregated; currently the tracking is handled by Q-Tracker and the field solving is executed by a modified version of QUINDI. Additionally, the RadTrack user interface allows for seamless start-to-end stitching of I/O exchange between certain codes, and the visualization canvas reinforces user directives in a near-real-time environment.
BNL, Upton, Long Island, New York
In order to preserve polarization during polarized proton operation for RHIC, two partial Siberian Snakes are employed in the AGS, where a number of strong spin depolarization resonances must be crossed. These Snakes cause a significant distortion to the injection lattice of the AGS and must be included in the on-line model. In this report we discuss the problem of modeling Snakes as optical elements, particularly as madx elements, and present results comparing measurements to the AGS on-line model.
Northern Illinois University, DeKalb, Illinois
ANL, Argonne
Most charged particle beams under realistic conditions have Gaussian density distributions in phase space, or can be easily made so. However, for several practical applications, beams with uniform distributions in physical space are advantageous or even required. Liouville’s theorem and the symplectic nature of beam’s dynamic evolution pose constraints on the feasible transformational properties of the density distribution functions. Differential Algebraic methods offer an elegant way to investigate the underlying freedom involving these beam manipulations. Here, we explore the theory, necessary and sufficient conditions, and practicality of the uniformization of Gaussian beams from a rather generic point of view.
LBNL, Berkeley, California
Tracy is an accelerator modeling and simulation code originally developed at LBNL in Pascal two decades ago*. Tracy evolved to Tracy2** which served as the basis for several derivative codes at other synchrotron light sources, including PSI, SSRL and Soleil. In most of these cases, the accelerator physics library was extracted and translated in C. At the ALS the library was re-written in C++ (Goemon***) in an object-oriented manner. Later this version was converted to C# with some effort spent on optimizing its performance****. Tracy# is the latest C# version upgraded to take advantage of the new features of the .NET Framework 3.5 and 4.0. It efficiently uses the modern language features of the C# and the standardized libraries of the .NET Framework for database, XML and networking. It also works with other .NET languages, such as IronPython and F# for interactive scripting. Although it is developed on Windows, MONO makes it portable to other operating systems including Linux.
ORNL, Oak Ridge, Tennessee
A development of a Python driving shell for the ORBIT simulation code is presented. The original ORBIT code uses the Super Code shell to organize accelerator related simulations. It is outdated, unsupported, and it is an obstacle for the future code development. A necessity of the replacement of the old shell language and consequences are discussed. A set of modules that are currently in the core of the pyORBIT code and extensions are presented. They include particle containers, parsers for MAD and SAD lattice files, a Python wrapper for MPI libraries, space charge calculators, TEAPOT trackers, and a laser stripping extension module.
Fermilab, Batavia
The Recycler is a fixed 8 GeV kinetic energy storage ring using permanent gradient magnets. A phase trombone straight section is used to control the tunes. For ProjectX , the H-particle extracted from the Linac will be striped and painted in the Recycler Ring and then the protons will be extracted into the Main injector. A long drifting space is needed to accommodate the injection chicane with stripping foils. In this paper, the existing FODO lattice in rr10 straight section being converted into doublet will be described. Due to this change, the phase trombone straight section has to be modified to bring the tunes to the nominal working point. On the other hand, a toy lattice of recycler ring is designed to simulate the end-shim effects of each permanent gradient magnet to add the flexibility to handle the tune shift to the lattice during the operation of 1.6·1014 with KV distribution of the proton beam to give ~0.05 of space charge tune shift . The comparison or the combinations of the two modification ways for the Recycler ring lattice will be presented also in this paper.
JAEA/TARRI, Gunma-ken
It is well-known that a charged-particle beam is Coulomb crystallized in the low-temperature limit. The feasibility of beam crystallization has been raised by the recent progress in beam cooling techniques and in understanding of the behavior of crystalline beams. To go a step further, we explore the dynamic behaviors of crystalline ion beams extracted from a storage ring, employing the molecular dynamics simulation technique. The effect of an extraction device and the following transport line on various crystalline beams has been investigated for extraction and transport of crystalline beams without collapse of the ordered structure.