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.
DESY Zeuthen, Zeuthen
INRNE, Sofia
The production of electron beams suitable for the successful operation of the European XFEL is studied at the Photo-Injector Test Facility at DESY, Zeuthen site (PITZ). The PITZ beamline is equipped with three dedicated stations for transverse emittance measurements and in the forthcoming shutdown period a section for transverse phase-space tomography diagnostics will be installed. The module contains four observation screens and therefore only four projections can be used in order to reconstruct an underlying phase-space density distribution. This work presents the performance of a number of reconstruction algorithms on limited projection sets using numerical data applied to the PITZ operating conditions. Different concepts for comparison between an original phantom and the reconstructed distribution are presented.
NSCL, East Lansing, Michigan
The cyclotron gas stopper is a newly proposed device to stop energetic ions in a high pressure helium gas and to transport them in a singly charged state with a gas jet to a vacuum region. Ions are injected into the region with vertical magnetic field, where they first meet a degrader and then move in helium gas. Due to multiple scattering, radioactive ions lose their energy, and the process is accompanied by ionization of helium. Externally applied voltage remove electrons and single-charged helium ions from the box. Under a certain incoming particle rate, the amount of ionized charge becomes large and cannot be removed completely. As a result, a neutralized plasma is accumulated in the center of the box and new incoming particles cannot be ejected from the field-shielded area. The present study focuses on a detailed understanding of space charge effects in the central ion extraction region. Particle-in-cell simulations of electron-helium plasma are based on self-consistent particle tracking in a field obtained from solution of Poisson’s equation for particle interacting via Coulomb forces. The paper analyzes the process and estimates the maximum possible incoming particle rate.
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.
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock
Demanding applications such as heavy ion fusion, high energy colliders and free electron lasers require the study of beam phenomena like space-charge induced instabilities, emittance growth and halo formation. Numerical simulations for instance with GPT (General Particle Tracer, Pulsar Physics) calculate the mutual Coulomb interactions of the tracked particles *. The direct summation of the forces is rather costly and scales with O(N2). In this paper we investigate a new approach for the efficient calculation of particle-particle interactions: the fast summation by Nonequispaced Fast Fourier Transform (NFFT) **, whereas the NFFT is a generalization of the well known Fast Fourier Transformation (FFT). We describe the algorithm and discuss the performance and accuracy of this method for several particle distributions.
TRIUMF, Vancouver
DAE/VECC, Calcutta
SFU, Burnaby, BC
The TRIUMF-VECC Electron Linac is a device for gamma-ray induced fission of actinide targets, with applications in nuclear physics and material science. A phased construction and commissioning scheme will eventually lead to a 50 MeV, 10 mA CW linac based on superconducting RF technology. Using this linac to deliver high intensity electron beams for applications such as an energy-recovered light source is a possibility integrated in the design study. The multitude of design and tuning parameters, diverse objectives and constraints require a comprehensive and efficient optimization scheme. For this purpose we adopted the genetic optimization program developed at Cornell University* as a prototype. Feature extensions were developed to accommodate specifics of the Electron Linac design, provide framework for more generic and integrated design process, and perform robustness/acceptance analyses. In this report we will discuss the method and its application to the design optimization of the Electron Linac. [1]. I. Bazarov and C. Sinclair, PRST-AB 8, 034202 (2005), and references therein.
LBNL, Berkeley, California
Tech-X, Boulder, Colorado
Laser plasma generated wakefields sustain accelerating gradient a thousand times higher than conventional accelerators, allowing acceleration of electron beams to high energy over short distances. Recently, experiments have demonstrated the production of high quality electron bunches at 1GeV within only a few centimeters. We present simulations, with the VORPAL framework, of the next generation of experiments, likely to use externally injected beams and accelerate them in a meter long 10 GeV laser plasma accelerator stage, which will operate in the quasi-linear regime where the acceleration of electrons and positrons is nearly symmetric. We will show that by using scaling of the physical parameters it is possible to perform fully consistent particle-in-cell simulations at a reasonable cost. These simulations are used to design efficient stages. In particular, we will show that we can use higher order laser modes to tailor the focusing forces, which play an important role in determining the beam quality. This makes it possible to increase the matched electron beam radius and hence the total charge in the bunch while preserving the low bunch emittance required for applications.
PSI, Villigen
For the 250 MeV test injector, it is planned to use a 2.6 cell RF gun originally developed for high current and charge operation in the CLIC test facility CTF-2. First start-to-end simulations assuming perfect field symmetries show, that this gun should be able to generate bunches at 200 pC with an emittance of below 400 nm rad, which would be compatible with the requirements for the SwissFEL. This gun uses double side coupled RF feeds in the last cell as well as tuners in the last two cells, which give transverse multipole effects in the field and phase space distribution and may lead to a deteriorated emittance. Since the beam in the last cell is already relativistic at energies between 4 and 6.4 MeV, this effect can be computed in a clean way by looking at the distributions of the integrated beam voltage at the cavity iris and deriving any transverse kicks via the Panovsky-Wenzel theorem. Doing this approach for the various operation modi planned for the PSI injector shows an emittance dilution well below the critical thresholds.
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.
ANL, Argonne
Northern Illinois University, DeKalb, Illinois
While COSY INFINITY provides powerful DA methods for the simulation of fragment separator beam dynamics, the master version of COSY does not currently take into account beam-material interactions. These interactions are key for accurately simulating the dynamics from heavy ion fragmentation and fission. In order to model the interaction with materials such as the target or absorber, much code development was needed. There were four auxiliary codes implemented in COSY for the simulation of beam-material interactions. These include EPAX for returning the cross sections of isotopes produced by fragmentation and MCNPX for the cross sections of isotopes produced by the fission and fragmentation of a 238U beam. ATIMA is implemented to calculate energy loss and energy and angular straggling. GLOBAL returns the charge state. The extended version can be run in map mode or hybrid map-Monte Carlo mode, providing an integrated beam dynamics-nuclear processes design optimization and simulation framework that is efficient and accurate. The code, its applications, and plans for large-scale computational runs for optimization of separation purity of rare isotopes at FRIB will be presented.
JLAB, Newport News, Virginia
Automation of DC photoinjector designs using a genetic algorithm (GA) based optimization is an accepted practice in accelerator physics. Allowing the gun cavity field profile shape to be varied can extend the utility of this optimization methodology to superconducting and normal conducting radio frequency (SRF/RF) gun based injectors. Finding optimal field and cavity geometry configurations can provide guidance for cavity design choices and verify existing designs. We have considered two approaches for varying the electric field profile. The first is to determine the optimal field profile shape that should be used independent of the cavity geometry, and the other is to vary the geometry of the gun cavity structure to produce an optimal field profile. The first method can provide a theoretical optimal and can illuminate where possible gains can be made in field shaping. The second method can produce more realistically achievable designs that can be compared to existing designs. In this paper, we discuss the design and implementation for these two methods for generating field profiles for SRF/RF guns in a GA based injector optimization scheme and provide preliminary results.
Muons, Inc, Batavia
Many measurements in particle and accelerator physics are limited by the time resolution. This includes particle identification via time-of-flight in major experiments like CDF at Fermilab, Atlas and CMS at the LHC. Large-scale systems could be significantly improved by large-area photo-detectors. The invention of a new method of making MCPs that promises to yield better resolution and be considerably less expensive than current techniques. Two different models for MCP simulations are suggested. Semi-analytical approach is a powerful tool for the design of static image amplifiers. Monte Carlo simulations can be successfully used for large area photo detectors with micron and Pico-second resolution range. Both approaches were implemented in the codes MCPS and MCS. The results of computer modeling are presented. References. 1. V.Ivanov, Z.Insepov, Pico-Second Workshop VII, The Development of Large-Area Pico-second Photo-Devices, Feb. 26-28, 2009; ANL. 2. V.Ivanov. The Code “Micro Channel Plate Simulator”, User’s Guide, Muons, Inc., 2009
Fermilab, Batavia
The beam-beam simulation code (BBSIMC) is a incoherent multiparticle tracking code for modeling the nonlinear effects arising from beam-beam interactions and the compensation of them using an electromagnetic lens. It implements short range transverse and longitudinal wakefield, dipole noise to mimic emittance growth from gas scattering, beam transfer function, and wire compensation models. In this paper, we report on recent improvements of the BBSIMC including a beam-beam compensation model using a low energy electron beam and an interpolation scheme of beam-beam forces. Some applications are presented for the Relativistic Heavy Ion Collider (RHIC) electron lens.
SLAC, Menlo Park, California
An x-ray Free-Electron Laser (FEL) calls for a high brightness electron beam. Generically, such a beam needs to be accelerated to high energy on the GeV level and compressed down to tens of microns, if not a few microns. The very bright electron beam required for the FEL has to be stable and the high quality of the electron beam has to be preserved during the acceleration and bunch compression. With a newly developed model independent global optimizer [*], here we report study for the control and error diagnostics of such a generic machine: magnetic elements, and RF cavities, and the electron beam parameters: the peak current, centroid energy, and trajectory. Collective effects, such as coherent synchrotron radiation, space charge, and various wakefields are incorporated in a parametric approach. Applicability and verification are detailed for the LINAC Coherent Light Source, an x-ray FEL project being commissioned at SLAC.
Fermilab, Batavia
In the paper the results are presented for calculation of the transverse wake and RF kick from the power and HOM couplers of the ILC acceleration structure. The RF kick was calculated by HFSS code while the wake was calculated by GdfidL. The calculation precision and convergence for both cases is discussed. The beam emittance dilution caused by the couplers is calculated for the main linac and bunch compressor of ILC.
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock
A single bunch instability caused by an electron cloud has been studied using analytical and semi-analytical methods with the wake field. The wake field in these cases was computed in the classical sense as excited electromagnetic field that transversally distorts those parts of the bunch trailing certain transversal offset in the leading part of the same bunch. The transversal wake force in this case is only depending on the longitudinal distance between the leading part of the bunch producing the wake force and the trailing parts of the bunch feeling the wake force. However during the passage of the bunch through the electron cloud the density of the electron cloud near the beam axis changes rapidly which does not allow the single variable approximation for the wake field. In this paper pursuing the idea of K. Ohmi we compute numerically the wake forces as two variable function of the position of the leading part of the bunch and the position of the bunch parts trailing the leading offset in the bunch.
KIT, Karlsruhe
FZK, Karlsruhe
ANKA is a synchrotron radiation source located in Karlsruhe, Germany. While the control system has always provided access to technical parameters, like power supply currents or RF frequency, direct access to physical parameters like tune or chromaticity has been missing. Thus the operator has to change and monitor the technical parameters manually and to calculate the physical parameters using separate tools. Therefore effort has been made to integrate the monitoring of physical parameters and simulation tools into the control system. At ANKA the MATLAB-based Accelerator Toolbox is used for simulation purposes, however the control system framework ("ACS") does not support MATLAB natively. For this reason, a software bridge has been created, which provides direct access to control system components from MATLAB. Thus operators can write their own MATLAB code simultaneously using simulation code and components from the control system. This system has already been used to automate measurements, thus allowing unattended long-term measurements, which have not been possible before. Future plans include creating a graphical user interface and various monitoring and stabilization loops.
IAP, Frankfurt am Main
For the development of high energy and high duty cycle RFQs accurate particle dynamic simulation tools are important for optimizing designs, especially in high current applications. To describe the external fields in RFQs, the Poisson equation has to be solved taking the boundary conditions into account. In PteqHI this is now done by using a finite difference method on a grid. This method will be described and simulation results will be compared to different RFQ particle dynamic codes.
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.
Northern Illinois University, DeKalb, Illinois
This research involves the development of a model of the small circumference (11.5 m) accelerator in which the earth’s field has a strong effect, and in which image charge forces are also included. The code used for this simulation was COSY Infinity 9.0 which uses differential algebras to determine high order map elements, as well as quantities such as chromaticity. COSY also uses Normal Form algorithms to determine the betatron tune and any amplitude dependent tune shifts which may result. The power of COSY is that it can derive the required quantities directly form the map without costly integration and tracking. Thus determining the map for both the default elements of the ring, plus the effects of image charge forces, and the earth’s magnetic field is both non-trivial, and important. This research uses the Baker Campbell Hausdorf method to determine the map of the ring with the external fields included. Furthermore COSY has the ability to directly implement misalignments within the beamline itself allowing for a study of their effects on beam dynamics. The presentation will include both coding development and applications to the University of Maryland Electron Ring.
RIKEN Nishina Center, Wako
PSI, Villigen
CIAE, Beijing
Since 1997 RIKEN Nishina center has been constructing a next-generation exotic beam facility, RI beam factory (RIBF), based on a powerful heavy ion driver accelerator . Its accelerator complex was successfully commissioned at the end of 2006 and started supplying heavy ion beams in 2007. The four ring cyclotrons (RRC, fRC, IRC and SRC) connected in series accelerate the energy of the heavy ion beams up to 400 MeV/u for the lighter ions such as argon and 345 MeV/u for heavier ions such as uranium. Intensity upgrade plans are under way, including the construction of a new 28 GHz superconducting ECR ion source. The new ECR will take all the succeeding accelerators and beam transport lines to a space charge dominant regime, which should be carefully reconsidered to avoid emittance growth due to space charge forces. Beam dynamics in the low energy cyclotron, RRC was studied by OPAL-cycl a flavor of the OPAL. The simulation results clearly show vortex motions in the isochronous field, resulting in round beam formation in the first 10 turns after the injection point. The possible increase of beam loss at beam extraction will be also discussed in this paper.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Presently, it runs at beam powers of ~0.2 MW, with upgrades in place to supply increased powers for the new Second Target Station. Studies are also under way for major upgrades in the megawatt regime. Underpinning this programme of operations and upgrades is a study of the high intensity effects that impose the limitations on beam power. Spallation is driven by a 50 Hz rapid cycling synchrotron, characterized by high space charge and fast ramping acceleration. High intensity effects are of particular importance as they drive beam loss, but are poorly understood analytically. This paper reviews development of the space charge charge code Set.
Fermilab, Batavia
Similar to many other linear accelerators, the High Intensity Neutron Source requires an RFQ for initial acceleration and formation of the bunched beam structure. The RFQ design includes two main tasks: a) the beam dynamics design resulting in a vane tip modulation table for machining and b) the resonator electromagnetic design resulting in the final dimensions of the resonator. The focus of this paper is on the second task including simulating high power operation of RFQ. We report complete and detailed RF modeling on the HINS RFQ resonator using simulating codes CST Microwave Studio (MWS) and Ansoft High Frequency Structure Simulator (HFSS). All details of the resonator such as input and output radial matchers, the end cut-backs etc have been precisely determined. In the first time a full size RFQ model with modulated vane tips, the power couplers and all tuners installed has been built, and a complete simulation of RFQ tuning has been performed. Finally some aspects of high power operation of RFQ have been investigated. Comparison of the simulation results with experimental measurements demonstrated excellent agreement.
PSI, Villigen
Modern particle tracking codes with their parallel processing capabilities generate data files of the order of 100 Gigabytes. Thus they make very high demands on file formats and post-processing software. H5PartROOT is a versatile and powerful tool addressing this issue. Based on ROOT, CERN's object-oriented data analysis framework developed for the requirements of the LHC era, and the HDF5 hierarchical data format, supplemented by an accelerator-specific interface called H5Part, H5PartROOT combines the statistical and graphical capabilities of ROOT with the versatility and performance of the HDF5 technology suite to meet the needs of the accelerator community. Providing the user with both a graphical user interface (data browser) and a shared library to be used in an interactive or batch ROOT session, H5PartROOT passes on the full power of ROOT without presupposing any knowledge about the intricacies of either ROOT or C++.
ANL, Argonne
Use of SDDS, the Self-Describing Data Sets file protocol and toolkit, has been a great benefit to development of several accelerator simulation codes. However, the serial nature of SDDS was found to be a bottleneck for SDDS-compliant simulation programs such as parallel elegant. A parallel version of SDDS would be expected to yield significant dividends for runs involving large numbers of simulation particles. In this paper, we present a parallel interface for reading and writing SDDS files. This interface is derived from serial SDDS with minimal changes, but defines semantics for parallel access and is tailored for high performance. The underlying parallel IO is built on MPI-IO. The performance of parallel SDDS and parallel HDF5 are studied and compared. Our tests indicate better scalability of parallel SDDS compared to HDF5. We see significant I/O performance improvement with this parallel SDDS interface.
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.
ANL, Argonne
The electron accelerator simulation software elegant is being parallelized in a multi-year effort. Recent developments include parallelization of input/output (I/O), frequency map analysis, and position-dependent momentum aperture determination. Parallel frequency map and momentum aperture analysis provide rapid turnaround for two important determinants of storage ring performance. Recent development of parallel Self-Describing Data Sets file (SDDS) I/O based on MPI-IO made it possible for parallel elegant (Pelegant) to take advantage of parallel I/O. Compared with previous versions of Pelegant with serial I/O, the new version not only enhances the I/O throughput with a good scalability, but also provides a feasible way to run simulations with a very large number of particles (e.g., 1 billion particles) by eliminating the memory bottleneck on the master with serial I/O. Another benefit of using parallel I/O is reducing the communication overhead significantly for the tracking of diagnostic optical elements, where the particle information has to be gathered to the master for serial I/O.
SLAC, Menlo Park, California
In a multi-bunch high current storage ring, beam generated fields couple strongly into the RF cavity coupler structure when beam arrival times are in resonance with cavity fields. In this study the integrated effect of beam fields over a several thousand RF periods is simulated for the complete cavity, coupler, window and waveguide system of the PEP-II B-factory storage ring collider. We show that the beam generated fields at frequencies corresponding to several bunch spacings for this case gives rise to high field strength near the ceramic window and could limit the performance of future high current storage rings such as PEP-X or Super B-factories.
SLAC, Menlo Park, California
High current B-Factory BPM designs incorporate a button type electrode which introduces a small gap between the button and the beam chamber. For achievable currents and bunch lengths, simulations indicate that potentials can be induced in this gap which are comparable to the breakdown voltage. This study characterizes beam induced voltages in the existing PEP-II storage ring collider BPM as a function of bunch length and beam current.
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.
LBNL, Berkeley, California
I present a new package for fast Truncated Power Series(TPS) calculation with no limit on the order and number of variables. This package has been used by PTC/FPP and integrated in MAD-X.
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.