| Paper | Title | Page |
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| THPAN001 | LOCO at the Australian Synchrotron | 3217 |
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| LOCO has been used during the commissioning of the Australian Synchrotron storage ring with a number of benefits. The LOCO (linear optics from close orbits) method compares a model response matrix to the real machine response matrix. Using this approach we are able to adjust the machine to match the ideal model. Results presented here show that LOCO has provided a high degree of control over a wide range of machine parameters. | ||
| THPAN002 | A Self-Consistent Model for Emittance Growth of Mismatched Charged Particle Beams in Linear Accelerators | 3220 |
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Funding: CNPq, Brazil The goal of this work is to analyze the envelope dynamics of magnetically focused and high-intensity charged particle beams. As known, beams with mismatched envelopes decay into its equilibrium state with a simultaneous increasing of emittance. This emittance growth implies that, in the stationary regime, the transverse phase-space of the beam is characterized by a tenuous population of hot particles around a dense population of cold particles. To describe this emittance growth, it was used the test-particle approach for the development of a simplified self-consistent macroscopic model, whose self-consistency is a result of the inclusion of the emittance growth into the envelope equation. The model is then compared with full N-particle beam simulations and the agreement is shown to be quite reasonable. The model revealed to be useful to understand the physical aspects of the problem and is computationally faster when compared with full simulations. |
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| THPAN003 | Image Effects on the Transport of Intense Beams | 3223 |
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Funding: CNPq and FAPERGS, Brazil, and U. S. AFOSR Grant No. FA9550-06-1-0345. We start by analyzing the image effects of a cylindrical conducting pipe on a continuous beam with elliptical symmetry. In particular, we derive an exact expression for the self-field potential of the beam inside the pipe without using any sort of multipole expansion. By means of a variational method, the potential for beams with varying density profiles along an elliptical shape is used to search for equilibrium solutions for intense beams. For that, we assume a uniform focusing in the smooth-focusing approximation. A curious result is that the product of the rms sizes along the ellipsis semi-axis stays constant as the pipe radius is varied. Finally, we prove that despite the nonlinear forces imposed by the image charges of an arbitrary shape conducting pipe, intense beams in uniform focusing fields preserve a uniform density in the equilibrium. |
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| THPAN004 | Runge-Kutta DA Integrator in Mathematica Language | 3226 |
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| The method of Truncated Power Series Algebra is applied in a Mathematica code to compute the transfer map for arbitrary equations of motion (EOM) describing a charged particle optical system. The code is a non-symplectic integrator – a combination between differential algebra module and a numerical solver of EOM. Using the symbolic system offers some advantages, especially in case of non-autonomous EOM (element with fringe-fields). An example is given – a soft-fringe map of a magnetic quadrupole. | ||
| THPAN005 | Short Quadrupole Parametrization | 3229 |
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Funding: National Research Council (Canada) The Enge function can be used to parametrize any element with well-defined edges. If an element is too short, however, there is no unambiguous definition of the effective edge. We first demonstrate that very little fringe field detail is needed to obtain accurate maps even up to fifth order. Then we go on to show a simple fitting algorithm that works well for short as well as long quadrupoles. The results are true whether the quads are magnetic or electrostatic. |
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| THPAN006 | Simulation of Decays and Secondary Ion Losses in a Betabeam Decay Ring | 3232 |
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| The beta decay of circulating ions in the decay ring of a Betabeam facility will give rise to secondary ions which differ in charge from the primary ions and will follow widely off-momentum orbits. A small fraction of these ions will be lost in the long straights, but the great majority of them will be lost in the arcs. Profiling of the losses requires detailed knowledge of the paths of these ions, which are distributed in phase space as well as around the ring circumference. We describe here a comprehensive model of ion decay, secondary ion tracking, and loss detection, which has been implemented in the tracking and simulation code Accsim. Methods have been developed to accurately track ions at large momentum deviations not amenable to conventional multiparticle tracking codes, as well as to detect their impact coordinates on vacuum chamber walls (possibly inside magnetic elements). In our simulation we have also included absorbers which are needed, along with appropriate lattice optimisations, to localize the majority of losses outside of the dipoles. From simulation results, some estimates of decay ring performance (in terms of loss concentration and management) will be given. | ||
| THPAN007 | Parallel Beam-Beam Simulation Incorporating Multiple Bunches and Multiple Interaction Regions | 3235 |
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| The simulation code COMBI has been developed to enable the study of beam-beam effects in the full collision scenario of the LHC, with multiple bunches interacting at multiple head-on and long-range collision points. The code is structured in a general way, allowing any number of bunches and interaction points (IP's) and procedural options for collisions, beam transport, and output of statistics and coherent mode data. The scale of this problem escalates into the parallel computing arena, and herein we will describe the construction of an MPI-based version of COMBI able to utilize arbitrary numbers of processors to support efficient calculation of multi-bunch multi-IP interactions and transport. After an overview of the basic methods and numerical components of the code, the computational framework will be described in detail and the parallel efficiency and scalability of the code will be evaluated. | ||
| THPAN008 | TRIUMF Extraction and 500 MeV Beamline Optics | 3238 |
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| The beamline 2A, one of TRIUMF cyclotron primary extraction beamlines, is 60m in length. It is now routinely operating up to 70uA (proton beam) at 500MeV for ISAC. ISAC requires a diffuse spot of specific size on the radioactive beam production target at the end of 2A. To help achieve this, we developed a program aimed at obtaining a better understanding and more accurate description of 2A optics and the extracted beam from the cyclotron. The beam envelopes along 2A were measured with profile monitors and compared with theoretical predictions. During the course of this work, we discovered that the transfer matrix, involved in the optics calclations, between the stripping foil and the beamline entrance was incorrect. After correcting this error, we obtained good agreement between the measured and calculated envelopes. We report on the details of this work as well as on a measurement of the beam characteristics as a function of stripper foil thickness. | ||
| THPAN009 | Orbit Properties of Non-Scaling FFAG Accelerators Using Constant-Gradient Magnets | 3241 |
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| Very high momentum compaction can be obtained in non-scaling FFAG accelerators using constant-gradient magnets with their field strengths decreasing outwards - sufficiently high that the magnet apertures (and vacuum chamber) need be little wider than in a strong-focusing synchrotron. Such machines are of great potential interest for applications in the 0.1 - 50 GeV energy range requiring higher intensities or pulse repetition rates than synchrotrons can provide. Analytic formulae have been developed for the basic orbit properties, particularly their momentum dependence, in various lattices, and give accurate enough results to provide a useful tool for choosing the magnet parameters. In this paper the dependences of orbit offset and circumference on momentum are explored for doublet lattices, and numerical results from the formulae are compared with those from lattice codes. | ||
| THPAN010 | Local Magnetic Error Estimation using Action and Phase Jump Analysis of Orbit Data | 3244 |
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Funding: This work is funded by DINAIN, Division Nacional de Investigacion, Universidad Nacional de Colombia, Bogota Colombia
It's been shown in previous conferences [*,**] that action and phase jump analysis is a promising method to measure normal quadrupole components, skew quadrupole components and even normal sextupole components. In this paper, the action and phase jump analysis is evaluated using new RHIC data.
*J. Cardona,et al, Procceedings of PAC 2005, Knoxville, Tennesse.**J. Cardona,et al, Procceedings of EPAC 2004, Lucerne, Switzerland. |
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| THPAN011 | Non Linear Space Charge Effects on Transverse Beam Stability | 3247 |
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Funding: This work is funded by DINAIN, Division Nacional de Investigacion, Universidad Nacional de Colombia, Bogota - Colombia. Simbad code is used to study the combined effect of external non linearities and space charge non linearities on the beam stability using a simple FODO lattice. Gaussian and parabolic particle distribution are used for these simulations and results are compared with Mohl and Metral theoretical results. |
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| THPAN013 | Computer-assisted Electron Beam Characterization at AIRIX Facility | 3250 |
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| AIRIX is a high current accelerator designed for flash X-ray radiography. The electron beam produced into a vacuum diode (2 kA, 3.5 to 3.8 MV, 60 ns) is extracted from a velvet cold cathode. For a complete beam characterisation at the diode output the following set of data is required: the primary beam current intensity, the primary beam energy, the 2D mean beam divergence, the 2D RMS beam size as well as the 2D transverse beam emittance. Part of these parameters is experimentally given by electrical sensors located into the beam line (I), by time resolved energy spread measurements (E) as well as by a classical beam imaging set-up (XRMS, YRMS). Unfortunately, XRMS and YRMS are measured downstream the diode output. Therefore, in order to get the relevant beam parameters at the right location (diode output) numerical data treatments are required. The TRAJENV beam transport code, coupled with the MINUIT minimization library, computes the unknown beam parameters at the diode output. In this paper, we propose to describe both experimental and theoretical approaches leading to the full beam characterization at the diode output. | ||
| THPAN014 | Beam Dynamics of the 100 MeV Preinjector for the Spanish Synchrotron ALBA | 3253 |
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A turn key 100 MeV linac is under construction, in order to inject electrons into the booster synchrotron of ALBA [1]. The linac will deliver electron beams according to two operation modes: a single bunch mode (1 to 16 pulses - 0.25nC each) and a multi-bunch mode (112ns - 4nC). We have calculated the beam dynamics, using our in house code, PRODYN [2], from the gun to the end of the linac. The beam behaviour, such as the radial control, the bunching process, the energy spread and emittance are analysed.
[1] D. Einfeld, "Status of the ALBA project", EPAC 06, Scotland, Edinburgh, June 2006.[2] D. Tronc and A. Setty, "Electrons RF auto-focusing and capture in bunchers", Linear Accelerator Conference 1988, Virginia. |
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| THPAN016 | Improving the SIS18 Performance by use of the Orbit Response Method | 3256 |
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| The SIS18 will be used as a booster for the new FAIR facility SIS100. A well-controlled linear optics of the SIS18 is necessary for further optimisation studies of nonlinear dynamics, resonance induced beam loss, dynamic aperture and nonlinear error measurements. The analysis of the orbit response matrix (ORM) is a powerful tool to calibrate the linear lattice models. We present results of several measurements on the SIS18 using the ORM and discuss the achieved improvement of the SIS18 performance. | ||
| THPAN017 | Scaling Laws for Space Charge Driven Resonances | 3259 |
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| Intrinsic fourth order space charge resonances may occur in linear as well as circular accelerators. The difference resonance ("emittance exchange" or "Montague" resonance) and the fourth order structure resonance lead to emittance variations depending on the strength of space charge, the crossing rate and the lattice. We present scaling laws for the Montague coupling resonance and for the fourth order structure resonance in terms of simple power law expressions that allow a straightforward application in design of accelerators subject to these mechanism. | ||
| THPAN018 | Stability Thresholds for Transverse Dipole Modes with Nonlinear Space Charge, Chromaticity and Octupoles | 3262 |
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Funding: Work supported by EU design study (contract 515873 -DIRACsecondary-Beams)
Transverse stability due to combinations of chromaticity effect, nonlinear space charge and octupoles of different polarities plays an important role in the determination of the impedance budget for the FAIR synchrotrons. Different analytic approaches [*,**,etc.] have been suggested, for which no direct comparison has been made so far. In order to clarify this issue we perform numerical investigations employing the particle tracking code PATRIC and compare results of simulation scans with predictions of a dispersion relation. Space charge effects within self-consistent and 'frozen' models are used for comparisons, connection to beam transfer function studies is addressed.
* D. Moehl, CERN/PS 95-08 (DI), (1995)** M. Blaskiewicz, Phys. Rev. ST Accel. Beams 4, 044202, (2001) |
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| THPAN019 | Utilizing a Wien Filter within the Beam Dynamics Simulation Tool V-Code | 3265 |
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Funding: This work was partially funded by EUROFEL (RIDS-011935), DESY Hamburg, and DFG (SFB 634). Beam dynamics simulations for computationally large problems are challenging tasks. On the one hand, to accurately simulate the electromagnetic field distribution within the whole device and the surrounding environment it is essential to consider all necessary device components including even small geometry details, complicated material distributions and the field excitations. On the other hand, further computational effort has to be put into precise modeling of the injected particle beam for detailed beam dynamics simulations. Under linear conditions, it is possible to separate the field calculation of the device from the computation of the particles self-field which can result in the proper application of diverse numerical schemes for the individual field contributions. In the paper it is demonstrated how the static electric and magnetic fields of a Wien filter beam line element can be treated as applied external fields within the beam dynamics simulation tool V-Code under the assumption that the interaction of the particle beam with the surrounding materials can be neglected. |
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| THPAN020 | A Dispersionless Algorithm for Calculating Wake Potentials in 3D | 3268 |
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Funding: This work is supported in part by the EU under contract number RIDS-011899 (EUROTeV). Accurate computations of wake potentials are an important task in modern accelerator design. Short bunches used in high energy particle accelerators excite very high-frequency fields. The geometrical size of accelerating structures exceeds the wavelength of the excited fields by many orders of magnitude. The application of codes such as TBCI, MAFIA or tamBCI are limited due to numerical dispersion effects and memory needs. Recently new codes like PBCI have been developed to overcome these problems. In this work the utilization of dispersionless directions in the leap-frog update scheme on a Cartesian grid are proposed for accurate simulations. In conjunction with a conformal modelling technique which allows for the full Courant time step a moving window technique can be applied. This was previously implemented in a 2D code. In this publication an extension to arbitrary three dimensional problems are presented. |
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| THPAN021 | Analysis of a Particle-In-Cell Code Based on a Time-Adaptive Mesh | 3271 |
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Funding: This work was partially funded by HGF (VH-FZ-005) and DESY Hamburg. For the coupled simulation of charged particles and electromagnetic fields several techniques are known. In order to achieve accurate results various parameters have to be taken into account. The number of macro-particles per cell, the resolution of the computational grid, and other parameters strongly affect the accuracy of the results. In the code tamBCI, based on a time-adaptive mesh, additional variables related to the adaptive grid refinement have to be chosen appropriately. An analysis of these values is carried out and the results are applied to the self-consistent simulation of the injector section of FLASH in 3D. |
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| THPAN022 | Conceptual Studies of the EUROTRANS Front-End | 3274 |
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Funding: Work supported by European Commission (contract number: FI6W-CT-2004-516520) EUROTRANS (EUROpean Research Programme for the TRANSmutation of High Level Nuclear Waste in an Accelerator Driven System) is calling for an efficient high-current CW front-end accelerator system. A combination of RFQ, normal conducting CH- (Crossbar H-mode) and super-conducting CH-DTL which aims to work at 352MHz and accelerate a 30mA proton beam to 17MeV has been studied as a promising candidate. The preliminary conceptual study results are reported with respect to beam dynamics design. |
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| THPAN023 | MERLIN-Based Start-to-End Simulations of Luminosity Stability for the ILC | 3277 |
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Funding: Supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. The International Linear Collider (ILC) requires the preservation of an ultra-small vertical emittance from the Damping Ring to the Interaction Point (IP) where the nanometre-sized beams are made to collide. It is well-known that ground motion and component vibration will need to be compensated by fast intra-train feedback systems and slower semi-continuous trajectory corrections. This complex system can in general only be modelled using simulation. In this paper, we report the progress and status of a full-featured so-called start-to-end simulation based on the MERLIN package of the ILC Low Emittance Transport (LET): Bunch compression, acceleration in the superconducting Main Linac, Beam Delivery System and finally collision at the IP. Realistic modelling of the beam-beam is included by using the code GUINEAPIG. Results based on several ground motion and vibration models and configurations of trajectory control are presented. |
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| THPAN025 | Evaluation of the Component Tolerances for the ILC Main Linac Assuming Global Linear Corrections | 3280 |
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Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme 'Structuring the European Research Area', contract number RIDS-011899. The small energy-spread, weak wakefields and relatively weak focusing in the ILC superconducting Main Linac result in little or no filamentation beam mismatch errors: linear correlations such as dispersion or cross-plane coupling from transverse misalignment or rotation errors of the quadrupoles respectively do not decohere as the beam is transported (accelerated) along the linac. Using correction available in the Beam Delivery System, the increase in projected emittance due to this linear correlations can to a large degree be corrected. In this paper we present component tolerances based on the assumption of a global correction at the end of the Main Linac. Some discussion on the impact of ground motion is also discussed. |
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| THPAN026 | Beam Profile Measurements and Analysis at FLASH | 3283 |
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| FLASH (Free Electron LASer in Hamburg) is a SASE FEL user facility at DESY, Hamburg. It serves also as a pilot project for the European XFEL. Although the slice emittance is a more appropriate parameter to characterize the SASE process, the projected emittance is a good indicator of the electron beam quality which can be measured in an easy and fast way. In this paper we present measurements of the projected emittance along FLASH. We also analyze the effect of the dispersion on transverse electron beam profiles. | ||
| THPAN027 | The Optimum Chromaticity Correction Scheme for Monochromatic and Non-Monochromatic Beam in HESR | 3286 |
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| The High Energy Storage Ring (HESR) of FAIR project consists of two achromatic arcs and two dispersionless straight sections. Due to the multi-functional purpose of the straight sections their contribution into the total chromaticity of the first and second order exceeds the arc's contribution and can affect on the non-monochromatic beam dynamic aperture. We investigate the optimum sextupole and octupole correction scheme for monochromatic and non-monochromatic beam to reach the larger dynamic aperture. | ||
| THPAN028 | HESR Lattice with Non-similar Arcs for the Stochastic Cooling | 3289 |
| The advanced HESR lattice with two arcs having the identical layout and the different slip factors are developed. The conception of arcs with three families of quadrupole allows easy adjusting the imaginary transition energy in one arc and the real transition energy in another arc with the absolute value close to the beam energy in whole required region from 3.0 GeV to 14 GeV. The arcs have the special feature, when the high order non-linearities are fully compensated inside of each arc, and therefore the dynamic aperture of the whole machine is conserved. We consider and compare two lattices with the same absolute value of transition energy: the current lattice with the negative momentum compaction factor in both arcs and the lattice having the negative and positive momentum compaction factors in different arcs correspondingly. Simultaneously we analyzed the 4 and 6 fold symmetry arcs machine. It allows making the conclusion that the 4 fold symmetry lattice is more suitable to get the required slip factors. At the lowest energy 3 GeV, the absolute value of slip factor in the imaginary and the real arc is related as ~0.09/0.02 correspondingly. For the higher beam energy this ratio is much bigger. | ||
| THPAN030 | Transverse Self-Consistent Modeling of a 3D Bunch in SIS100 with MICROMAP | 3292 |
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Funding: EU-DESIGN STUDY (contract 515873 - DIRACsecondary-Beams) We present the upgrade of the MICROMAP beam dynamics simulation library to include a 2 1/2 D space charge modeling of a 3D bunch using local slices in z. We discuss the parallelization technique, the performances, several tests and comparison with existing well-established analytical/numerical results in order to validate the code. An application to the SIS100 synchrotron of the FAIR project at GSI is outlined. |
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| THPAN031 | Optimization of the Beam Line Characteristics by Means of a Genetic Algorithm | 3295 |
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| The optimization of the optics in a LINAC requires a very demanding tuning of the involved parameters, particularly in the case of high brightness electron beams applied to the production of X-ray in a Thomson back-scattering source. The relationship between the parameters is non-linear and it is not possible to treat them as independent variables, causing the impossibility of setting them handily. A genetic algorithm is a powerful tool able to circumvent this difficulty. We have applied the genetic algorithm to the case of the SPARC beam line. | ||
| THPAN032 | Study of the Beam Dynamics in a Linac with the Code RETAR | 3298 |
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| The three-dimensional fully relativistic and self-consistent code RETAR has been applied to model the dynamics of high-brightness electron beams and in particular to assess the importance of the retarded radiative part of the emitted electromagnetic fields in all conditions where the electrons experience strong accelerations. In this analysis we evaluate the radiative energy losses in the electron emission process from the photocathode of an injector, during the successive acceleration of the electron beam in the RF cavity and the focalization due to the magnetic field of the solenoid, taking also into account the e.m. field of the laser illuminating the cathode and the inhomogeneities on the cathode surface. The analysis is specifically carried out with parameters of importance in the framework of the SPARC and PLASMONX projects. | ||
| THPAN033 | Design Study of the Dipole Magnet for the RHIC EBIS High Energy Transport Line | 3301 |
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| The design studies of the dipole magnet for EBIS HEBT line is proceeding. The RHIC EBIS is a new high current highly charged heavy ion preinjector for RHIC. The dipole magnet discussed in this paper will be used to guide the beam to existing heavy ion injection line to Booster. A total of 145 degrees bend is provided by two identical dipole magnets with a slit between these magnets to pass only intended charge state ions. Also this magnet has a hole in the side wall to pass the beam from the existing Tandem Van de Graaff. The performance of this magnet calculated by TOSCA and the results of the particle tracking calculation are described. | ||
| THPAN034 | New Simulation Code for Synchrotron Radiation Based on a Real Beam Orbit | 3304 |
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A computer code to simulate synchrotron-radiation power and spatial distributions has been developed based on the method by T. Abe and H. Yamamoto*, where a real beam orbit is obtained by fitting measurements of beam-position monitors (BPMs) with some offset corrections for BPMs and magnet alignments. In this paper, the basic performance and application are presented. This code has been rewritten in Fortran95 so as to obtain expectable maximal speed-up by parallel computing, aiming at online alarm systems to take precautions against synchrotron-radiation damage, toward higher beam current accelerators.
* T. Abe and H. Yamamoto, Phys. Rev. ST Accel. Beams 7, 072802 (2004) |
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| THPAN036 | ABCI Progresses and Plans: Parallel Computing and Transverse Napoly-Shobuda Integral | 3306 |
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| In this paper, we report the recent progress and future plans of ABCI. First, ABCI now supports parallel processing in OpenMP for a shared memory system, such as a PC with multiple CPUs or a CPU with multiple cores. The new ABCI also supports the dynamic memory allocation for nearly all arrays for field calculations so that the amount of memory needed for a run is determined dynamically during runtime. A user can use any number of mesh points as far as the total allocated memory is within a physical memory of his PC. As a important progress of the features, the transverse extension of Napoly integral (derived by Shobuda) has been implemented to the new ABCI: it permits calculations of wake potentials in structures extending to the inside of the beam tube radius or having unequal tube radii at the two sides not only for longitudinal but also for transverse cases, and still the integration path can be confined to a finite length, by having the integration contour beginning and ending on the beam tubes. The future upgrade plans will be also discussed. The new ABCI is available as a Windows stand-alone executable module so that no installation of the program is necessary. | ||
| THPAN037 | Beam-Beam Effects Observed at KEKB | 3309 |
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| KEKB is an e+ e- collider with a world-highest luminosity of 1.7 x 1034 /cm2/s. It has a half-crossing angle of 11 mrad. We are installing crab cavities for the purpose of eliminating effects of crossing angle in the begining of 2007. Another feature of KEKB is that its operating points are very close to the half interger in the horizontal direction. This report summarizes beam-beam effects observed at KEKB. | ||
| THPAN038 | Generation and Acceleration of High Brightness Electron Bunch Train in ATF of KEK | 3312 |
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| Laser Undulator Compact X-ray source (LUCX) is a test bench for compact high brightness X-ray generator at KEK in order to demonstrate the possibility on K-edge digital subtraction angiography, based on the Compton Scattering. For this project, one of the challenging problems is to generate and accelerate high brightness multi-bunch electron beams, compensating the energy difference due to beam loading effect. In this paper, we calculate the transient beam loading voltage and energy gain from RF field in standing wave gun cavity and traveling wave accelerating tube for multi-bunch train, considering the process of propagation, buildup of RF field in them and the special RF pulse shape. We generated and accelerated 100 bunch electron beam train with 50nC, which beam loading effect was compensated effectively by adjusting the laser injection timing. By BPM and OTR system, we measured the electron beam energy bunch by bunch. The average energy of 100 bunch train is 40.5MeV and maximum energy difference bunch to bunch is 0.26MeV, the relative energy spread of single bunch is about 0.13%. The transverse emittance can be optimized roughly to 3.6 pimm.mrad. | ||
| THPAN039 | Space Charge Effects for JPARC Main Ring | 3315 |
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| The JPARC Main Ring should provide the beam power up to 0.8MW at the maximum energy of 50GeV. According to the basic operation scenario during the injection period 8 bunches with the maximum bunch power up to 100kW should be created around the ring. In frame of this report we present the space charge effects in combination with the nonlinear resonances, caused by the machine imperfection, for different beam intensities and different machine operation scenario, including the Main Ring RF system, the collimator system of the RCS-MR beam line and the MR collimation system. The measured field data for main magnets of the ring has been taken into account for this study. | ||
| THPAN040 | Study of Halo Formation in JPARC-MR | 3318 |
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| JPARC is a high intensity proton facility which is constructing as a joint project JAERI-KEK in Japan. JPARC equips two proton ring accelerators, Rapid Cycle Synchrotron (RCS) and Main Ring (MR). We discuss the space charge effect of MR in this paper. The proton beam with the population of 4.15·1013 x 8 bunches is accelerated from 3 GeV to 50 GeV and extracted with 0.5 Hz in MR. Beam loss during the acceleration is caused by an incoherent emittance growth due to the space charge force. We discuss the emittance growth and halo formation using a computer simulation based on the particle in cell method. | ||
| THPAN042 | Recent Progress of Optics Correction at KEKB | 3321 |
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| In recently KEKB operation, we have to tune the operation parameters during about one week in order to recover the peak performance after the optics correction. This wrong reproducibility of the luminosity is a significant problem for the integrated luminosity of the physics run. In this paper, we present the progress of the optics correction to improve the reproducibility of the machine performance. | ||
| THPAN043 | Comparison of Trajectory Between Modeling and Experiment for J-PARC Linac | 3324 |
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| In the beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) linac, three simulations codes are used to model the accelerator. We have compared with the experimental results obtained in the beam commissioning to date, where a basic agreement has been confirmed between the modeling and the actual beam behavior. | ||
| THPAN044 | Global COD Correction of SAGA-LS Storage Ring | 3327 |
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| SAGA Light Source is a medium size light source which has been operated from February, 2006. The stored beam orbit has been corrected by a closed orbit correction system consisted of 24 beam position monitors, 40 steering magnets and PC-LabView based control system. The singular value decomposition method has been applied for the global COD correction by using a measured response matrix. As a result, the standard deviation of the orbit error around the ring was reduced to 20 micro-meters both for horizontal plane and for vertical plane, respectively. | ||
| THPAN045 | Explicit Time Domain Boundary Element Scheme for Dispersion-free Wake Field Calculation of Long Accelerator Structures | 3330 |
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| This paper introduces a new explicit scheme with a moving window option for wake field calculation of long accelerator structures. This scheme is based on a time domain boundary element method (TDBEM) which uses a retarded Kirchhoff boundary integral equation on interior region problems. As a corollary of this boundary integral equation, our approach allows a conformal modeling of a structure and time domain wake field simulation without numerical grid dispersion errors in all spatial directions. The implementation of a moving window technique in the framework of TDBEM is presented and it is shown that this moving window technique allows to significantly reduce memory requirement of the TDBEM scheme in the short range wake field calculation. Several numerical examples are demonstrated for the TESLA 9-cell cavity and tapered collimators. The results of the new TDBEM scheme are compared with that of finite difference codes. | ||
| THPAN046 | Extension of Napoly Integral for Transverse Wake Potentials to General Axisymmetric Structure | 3333 |
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| The Napoly integral for wake potential calculations in the axisymmetric structure is a very useful method because the integration of Ez field can be confined in a finite length instead of infinite length by deforming the integration path, which reduces CPU time for accurate calculations. However, his original method cannot be applied to the transverse wake potentials in a structure where the two beam tubes on both sides have unequal radii. In this case, the integration path needs be a straight line and the integration stretches out to an infinite in principle. We generalize the Napoly integrals so that integrals are always confined in a finite length even when the two beam tubes have unequal radii, for both longitudinal and transverse wake potential calculations. The extended method has been successfully implemented to ABCI. | ||
| THPAN048 | Numerical Solver with CIP Method for Fokker Planck Equation of Stochastic Cooling | 3336 |
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A Fokker Planck equation for a Stochastic cooling* is solved by using the CIP method**. The Fokker Planck equation can be described in a convection-diffusion equation as a function of time and energy. The equation is a non linear form and the evolution of the distribution function should be numerically solved. The CIP method, which is an effective scheme to solve the convection term numerically, is applied to the Fokker Planck equation of the Stochastic cooling. By using the CIP method for the numerical solver, we can effectively calculate the time-dependent Fokker Planck equation in more few computational costs. The developed numerical solver can give us the energy spectrum of the particle distribution during the beam cooling. The simulation results show the good agreements compared with the experimental results.
* S. Van der Meer, CERN/PS/AA/78-22, 1978.** T. Yabe and T. Aoki, Comp. Phys. Commun. 66 (1991) 219. |
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| THPAN049 | Particle Dynamics at Stagnation Point during Longitudinal Bunch Compression of High Current Beams | 3339 |
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Funding: This work is supported by MEXT (Ministry of Education, Culture, Sports, Science and Technology) and JSPS (Japan Society for the Promotion of Science) No.17740361. For researches in high energy density physics and inertial confinement fusion by using heavy ion beams, high-current beam dynamics should be understood well. The heavy ion beam is longitudinally compressed by a head-to-tail velocity tilt applied from high-power induction voltage modules. In this study, emittance growth due to the longitudinal bunch compression is numerically investigated by using a particle-in-cell simulation. The code developed is dealt with three dimensional particle motions, and 2D transverse electric field is solved by Poisson equation coupled with 1D longitudinal electric field. We indicate the particle dynamics due to the non-linear longitudinal-transverse coupling effect around the stagnation point in the longitudinal compression. |
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| THPAN051 | Update on the ILC DR Alternative Lattice Design | 3342 |
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In order to reduce the cost for ILC damping rings, an alternative lattice which is different from the baseline configuration design has been designed previously with modified FODO arc cells, and the total quadrupole and sextupole number has been reduced largely, compared with the baseline design. At the same time, to decrease the total cost involved in constructing access shafts needed to supply power, cryogenics etc. for the wigglers and other systems, the number of wiggler sections is decreased from 8 to 4, and further to 2. However, the momentum compaction of this lattice can not be tuned freely. In this paper, a new ILC damping ring lattice design with a variable momentum compaction will be presented, followed by the single particle dynamics associated studies.
*ypsun@ihep.ac.cn |
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| THPAN052 | Study of Generic Front-end Designs for ERL Based Light Sources | 3345 |
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Funding: supported by National 973 Projects and the U. S. Department of Energy Contract No. DE-AC05-06OR23177 We present work directed at examining the performance of various front end components of an ERL based light source. These include electron source, bunch compression, merger, and accelerating sections, with parameter space dictated by proposed facilities (at FSU and Beijing University). These facilities share enough common structural features to make the study applicable to both to a large extent. In this report we will discuss the 6D phase space evolution through the front end based on simulation, with reliable modeling of magnetic and superconducting RF fields. Discussion will be devoted to relative merits of alternative designs, robustness and operational scenarios. |
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| THPAN054 | Experiment on a Cold Test Model of a 2-Cell SC Deflecting Cavity for ALS at LBNL | 3348 |
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| Deflecting Cavities can be used to generate sub-pico-second X-ray pulse and are proposed at ALS at LBNL. A 2-cell structure has been simulated earlier to achieve the required deflecting voltage with damping waveguide to get low impedance. An aluminum cold test model has been made to demonstrate the simulation and the idea for damping LOM with waveguide. Field distribution as well as (R/Q)s are measured using 'bead-pull' method. Qs with/without waveguide loaded are measured and compared with simulation. Detailed configuration and experiment progress is presented. | ||
| THPAN055 | Theoretical Study of Medium Emittance Lattice at HLS | 3351 |
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Funding: Supported by National Natural Science Foundation of China, No. 10175062 & No.17175100
A method of injection analysis of small electron storage ring is introduced, and several medium emittance lattices are proposed. By analyzing the injection, working point of the lattice is selected at the vicinity of half integer resonance lines, and emittance is around 60nmrad, the linear and nonlinear properties can be satisfied for injection and store.
LIU Zu-Ping, Li Wei-Min. Progress of the NSRL Phase Two Project. In proceedings of the Second Asia Particle Accelerator Conference, Beijing, China, 2001, 235-238 |
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| THPAN056 | Design Study of Compact Cyclotron Magnets in Virtual Prototyping Environment | 3354 |
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Funding: This work is supported by National Nature Science Foundation of China under Grant 10435030. An intelligent magnet design, modelling and optimization method with the aid of beam dynamics analysis and three dimensional magnetic field calculation is introduced. The whole procedure is implemented in an integrated virtual prototyping environment built with python language. As a case study, the main magnet design of a 16MeV H- compact cyclotron is illustrated. Both the field isochronism and transversal focusing of the beam can be fulfilled, and the mechanical analysis is performed to validate the feasibility in mechanics. |
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| THPAN057 | Error Analyses of the PEFP 20/100-MeV Beamlines | 3357 |
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Funding: This work was supported by the 21C Frontier R&D program sponsored by Ministry of Science and Technology, Korean Government. The proton engineering frontier project (PEFP) 100-MeV proton linac has two main beamline systems to extract and deliver the proton beam to the user. The one is designed to extract 20-MeV proton beams at the medium energy transport system of the linac and to deliver them to five target stations through a beam switching system. The other is able to extract 100-MeV proton beams at the end of the linac and to deliver them to another five target stations trough a beam distribution system. We have completed the detailed beam optics designs of the beamline system and performed intensive error analyses to set the marginal limits of engineering errors of the beamline components by using a dedicated beam transport code. The paper presents the error analysis results of the PEFP beamline systems along with their characteristics and beam optics designs. |
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| THPAN058 | Beam Tracking Simulations for a BPM-based Energy Spectrometer Prototype for ILC | 3360 |
| T-474 at SLAC is a prototype BPM-based energy spectrometer for the ILC. A 4-dipole chicane is used with mid-chicane dispersion of 5-mm and magnetic fields of ~1 kGauss; these match the current ILC parameters. Better than 100 part-per-million (ppm) accuracy is needed for ILC energy measurements, requiring better than 50 ppm accuracy for magnetic field integral measurements. Code for beam tracking through the spectrometer chicane was developed. Magnetic field maps for dipole magnets obtained from the measurements at SLAC are used. Different aspects of the magnetic field influence to the beam deflection value are discussed. Results of the beam dynamics study using the measured magnetic fields for T-474 chicane to estimate magnetic effects on capabilities for the energy measurements are also reported. | ||
| THPAN059 | Proposal for an Enhanced Optical Cooling System Test in an Electron Storage Ring | 3363 |
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| We are proposing to check experimentally the new idea of Enhanced Optical Cooling (EOC) in an electron storage ring. The experiment will confirm new fundamental processes in beam physics and demonstrate new unique possibilities in cooling technique. It will open important applications of EOC in nuclear physics, elementary particle physics and in light sources (LS) based on high brightness electron, proton, and ion beams. | ||
| THPAN060 | 3D PIC Method Development for Simulation of Beam-Beam Effects in Supercolliders | 3366 |
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| A new Beam-Beam simulation code based on a 3D PIC method has been developed. Taking into account to the full extent the three-dimensional nature of the interaction can be useful for studies of some thin questions such as a pinch effect at large crossing angles in ILC and Crab Waist properties in SuperB Factory. Colliding electron and positron beams move in the region shaped as parallelepiped. The physical process is described by Vlasov-Liouville equations and a set of Maxwell equations that interrelate of the densities of charge and current, and intensities of electric and magnetic fields. The examples of the electron and positron bunches movement and collision simulation are presented. | ||
| THPAN063 | Analytic Description of the Phase Slip Effect in Race-Track Microtrons | 3369 |
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| Design of modern race-track microtrons (RTMs) requires better understanding of the longitudinal beam dynamics in these machines, in particular of the phase slip effect which is important for low energy beams. We generalize an analytical approach for the description of the synchronous particle motion and synchrotron oscillations, developed in our previous papers, by including the fringe fields of the RTM end magnets. Explicit, though approximate, formulas are derived and an algorithm for improving their accuracy is formulated. The efficiency of the analytic description is checked numerically, in particular by tracking simulations using the RTMTRace code. Explicit examples of low energy injection schemes and applications of this formalism for the injection phase fixing are given. | ||
| THPAN065 | Beam Loss Map Simulations and Measurements in the CERN PS | 3372 |
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| Numerical tools providing detailed beam loss maps, recently developed for the design of the LHC collimation system, were adapted to the CERN Proton Synchrotron in order to reproduce the observed beam loss patterns. Using a MADX optics sequence model, these tools are able to track a large number of particles with Sixtrack and interact with a realistic aperture model to simulate particle losses all around the ring. The modeled loss maps were finally compared with beam loss measurements at several energies and for a variety of beams accelerated in the synchrotron. | ||
| THPAN066 | Improvements in FAKTOR2, a Code to Simulate Collective Effect of Electrons and Ions | 3375 |
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Funding: Supported by the European Community under the 6th Framework Programme "Structuring the European Research Area". The electrostatic Particle in Cell code 'Faktor2' is extended to 3D, and is parallelised. Results for electron cloud buildup in end regions of damping ring dipoles for next generation linear colliders are presented. |
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| THPAN068 | Wakefield Models for Particle Tracking Codes | 3378 |
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| Wakefields have a considerable effect on beam dynamics and they must not be neglected for emittance growth studies, background estimates and other problems. The codes used for these problems are normally not capable of self-consistent wakefield calculations. They should thus be extended with either analytical models or export the wakefields numerically evaluated with other codes (such as Gdfidl) when analytical models are not feasible. We discuss both approaches and present their implementation in PLACET, MERLIN and BDSIM. The simulation results for the ILC and CLIC beam delivery systems are given as an example. Results produced with different codes are compared. | ||
| THPAN070 | Advances in MAD-X using PTC | 3381 |
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| For the last few years the MAD-X program makes use of the Polymorphic Tracking Code (PTC) to perform calculations related to beam dynamics in the nonlinear regime. An important new feature is the extension of the matching module to allow fitting of non-linear parameters to any order. Moreover, calculations can now be performed with parameter dependence defined in the MAD-X input. In addition, the user can access the PTC routines for the placement of a magnet with arbitrary position and orientation. This facilitates the design of non-standard lattices, in particular since a 3D visualization of a lattice is now available. For the LHC studies during commissioning it is of special interest that one has access to within the thick PTC elements which allows e.g. to find PTC Twiss parameters at any point in the ring. Lastly, the beam-beam element has been added to PTC to complete the set of elements available in MAD-X proper. | ||
| THPAN071 | LHC On-Line Modeling | 3384 |
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| The LHC machine will be a very demanding accelerator with large nonlinearities to control. Particle loss in the LHC must be actively controlled to avoid damage to the machine. Therefore any relevant adjustment to the machine must be checked beforehand with a proper modeling tool of the LHC. The LHC On-Line Modeling is an attempt to provide such an analysis tool mainly based on the MAD-X code. The goal is not to provide real-time system to control LHC but rather a way to speed up off-line analysis to give results within minutes. There will be a rich spectrum of applications like closed orbit corrections, beta-beating analysis, optimization of correctors and knob settings to name a few. This report will outline how in detail the On-Line Modeling will be in embedded in the LHC control system. It will also be reported about progress in applying this analysis tool to the SPS machine and to the commissioning of the CNGS. | ||
| THPAN072 | A Concept for the LHC Luminosity Upgrade Based on Strong Beta* Reduction Combined with a Minimized Geometrical Luminosity Loss Factor | 3387 |
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| A significant increase of the LHC beam current touches physics limits as collective effects, electron-cloud, heat load, collimation and machine protection. We propose an upgrade scheme mainly based on a stronger focusing, with a beta* of 10 cm, requiring a triplet quadrupole aperture of around 130 mm. The performance is further improved if the triplet is based on the Nb3Sn technology. In the present baseline, this beta* reduction provides a negligible luminosity increase: this approach requires a drastic action to minimize the crossing angle, while the beam separation at the long-range encounters has to be increased. This is provided by an early separation scheme made of small dipoles inside the detectors. Optionally, a small angle crab cavity scheme may totally suppress the residual crossing angle. The quadrupole aperture is calculated to allow a larger gap for the collimator, suppressing their impedance limitation. This concept offers high performance while significantly reducing the risks associated to a beam current increase; it opens as well new issues that deserve further studies, such as the dipole integration in the detector, and the correction of the triplet aberrations. | ||
| THPAN074 | Space-Charge Compensation Options for the LHC Injector Complex | 3390 |
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| Space-charge effects have been identified as the most serious intensity limitation in the CERN PS and PS booster, on the way towards ultimate LHC performance and beyond. We here explore the application of several previously proposed space-compensation methods to the two LHC pre-injector rings, for each scheme discussing its potential benefit, ease of implementation, beam-dynamics risk, and the R&D programme required. The methods considered include tune shift and resonance compensation via octupoles, nonlinear chromaticity, or electron lenses, and beam neutralization by an electron cloud, plasma or negative ions. | ||
| THPAN075 | Modeling Incoherent Electron Cloud Effects | 3393 |
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| Incoherent effects driven by an electron cloud could seriously limit the beam lifetime in proton storage rings or blow up the vertical emittance in positron ones. Different approaches to modeling these effects each have their own merits and drawbacks. We compare the simulation results and computing time requirements from a number of dedicated codes under development over the last years, and describe the respective approximations for the beam-electron cloud interaction, the accelerator structure, and the optical lattice, made in each of these codes. Examples considered include the LHC, CERN SPS, RHIC, and the ILC damping ring. Tentative conclusions are drawn and a strategy for further codes development is outlined. | ||
| THPAN076 | Progress on H5Part: A Portable High Performance Parallel Data Interface for Electromagnetics Simulations | 3396 |
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| Significant problems facing all experimental and computational sciences arise from growing data size and complexity. Common to all these problems is the need to perform efficient data I/O on diverse computer architectures. In our scientific application, the largest parallel particle simulations generate vast quantities of six-dimensional data. Such a simulation run produces data for an aggregate data size up to several TB per run. Motived by the need to address data I/O and access challenges, we have implemented H5Part, an open source data I/O API that simplifies use of the Hierarchical Data Format v5 library (HDF5), which is an industry standard for high performance, cross-platform data storage and retrieval that runs on all contemporary architectures from large parallel supercomputers to laptops. H5part, which is oriented to the needs of the particle physics and cosmology communities, provides support for parallel storage and retrieval of particles, structured and in the future unstructured meshes. In this paper, we describe recent work focusing on I/O support for unstructure meshes and provide data showing performance on modern supercomputer architectures. | ||
| THPAN078 | An Elementary Analysis of Coupled-Bunch Instabilities | 3399 |
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| We reconsider the equations of motion of wakefield coupled bunches in the light of recent developments in Delay Differential Equations. In the case of uniform resistive wall in a circular accelerator, we demonstrate an alternative way to obtain the growth rates. For each Fourier mode of bunch displacements, we show that multiple time domain modes can arise from an exact solution of the equation of motion. The growth rate as it is commonly defined corresponds to only one of them. The amplitude of each Fourier mode can therefore evolve with time in a way is not simply exponential. This is a result that has been observed in simulations of wakefield coupled bunches. | ||
| THPAN079 | Emittance Growth Due to High Order Angular Multipole Mode Wakefields in the ILC-BDS Collimators | 3402 |
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| The passage of an off-axis bunch through the collimator gap induces higher order mode wakefields which can lead to emittance growth and consequently can affect the luminosity at the IP - a major concern for the ILC. The emittance growth due to high order angular multipole mode wakefields is calculated and beam profiles at the IP are presented in this paper. | ||
| THPAN081 | Collimator Wakefields: Formulae and Simulation | 3405 |
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| The effect of a leading particle on a trailing particle due to resistive and geometric wakefields in collimators can be described by expanding in a series of angular mode potentials Wm(s). Several formulae for these are given in the literature. We compare these formulae with numerical predictions from codes that solve the EM field equations, and explore the claimed regions of validity. We also explore how the EM code results can be used to numerically obtain angular mode potentials suitable for use in tracking codes. | ||
| THPAN082 | Implementation of Spread Mass Model of Ion Hose Instability in Lamda | 3408 |
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Funding: Work supported by Los Alamos National Laboratory. The ion-hose instability sets limits on the allowable vacuum in the DARHT-2 linear induction accelerator (2kA, 18.6MeV, 2μs). Lamda is a transport code which advances the beam centroid and envelope in a linear induction accelerator from the injector to the final focus region. The code computes the effect of magnet misalignments, beam breakup instability, image-displacement instability, and gap voltage fluctuation on the beam. In this work, we have implemented the Spread Mass (SM) model of ion-hose instability into Lamda so that we can examine quickly the operating parameters for the experiments. Unlike the ordinary SM ion-hose code which assumes the uniform axial magnetic field, Lamda ion-hose calculation includes varying axial magnetic field, accelerating beam, gas pressure file, varying beam radius and elliptical beam. The benchmarks against a semi-analytical SM code and the particle-in-cell code Lsp, and a prediction of ion-hose instability for a 2.5MeV-1.4kA beam in the DARHT-2 are presented. |
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| THPAN083 | A Beam-Slice Algorithm for Transport Simulations of the DARHT-2 Accelerator | 3411 |
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| A beam-slice algorithm has been implemented into the Lsp particle-in-cell (PIC) code to allow for efficient simulation of beam electron transport through a long accelerator. The slice algorithm pushes beam particles along a virtual axial dimension and performs a field solve on a transverse grid which moves with the particle slice. Any external electric and magnetic fields are also applied to the slice at each time step. For an axisymmetric beam problem the slice algorithm is very fast compared to full 2-D r-z PIC simulations. The algorithm also calculates beam emittance growth due to mismatch oscillations, in contrast to standard envelope codes which assume constant emittance. Using the slice algorithm we are able to simulate beam transport in the DARHT-2 accelerator at LANL from the region just downstream of the diode to the end of the accelerator, a distance of about 50 meters. Results from the slice simulation are compared to both 2-D PIC simulations and the beam envelope code Lamda. The sensitivity of the final emittance to imperfect tuning of the transport solenoids is calculated. | ||
| THPAN084 | Self Consistent Monte Carlo Method to Study CSR Effects in Bunch Compressors | 3414 |
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Funding: Supported by DOE grant DE-FG02-99ER41104 and contract DE-AC02-76SF00515. We report on the implementation of a self consistent particle code to study CSR effects on particle bunches traveling on arbitrary planar orbits. Shielding effects are modeled with parallel perfectly conducting plates. The "vertical" charge distribution is assumed to be stationary. The macroscopic Maxwell equations are solved in the lab frame while the equations of motion are integrated in the beam frame interaction picture where the dynamics is governed by the self fields alone. We study different methods to construct a smooth charge density from particles, e.g. gridless nonparametric curve estimation and charge deposition plus filtering. We present numerical results for bunch compressors. In particular, we study different initial distributions. The transverse initial distribution is Gaussian and we study different initial longitudinal distributions: Gaussian, parabolic and nonlinear chirp. A parallel version of the code has been implemented and this will speed up parameter analysis and allow micro-bunching studies. |
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| THPAN085 | Two-Stream Instability Analysis For Propagating Charged Particle Beams With a Velocity Tilt | 3417 |
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Funding: This research was supported by the U. S. DOE through Lawrence Berkeley National Laboratory, Princeton Plasma Physics Laboratory for the Heavy Ion Fusion Science-Virtual National Laboratory.
The linear growth of the two-stream instability for a charged particle beam that is longitudinally compressing as it propagates through a background plasma (due to an applied velocity tilt) is examined. Detailed, 1D particle-in-cell simulations are carried out to examine the growth of a wave packet produced by a small amplitude density perturbation in the background plasma. Recent analytic and numerical work by Startsev and Davidson [1] predicted reduced linear growth rates, which are indeed observed in the simulations. Here, small-signal asymptotic gain factors are determined in a semi-analytic analysis and compared with the simulation results in the appropriate limits. Nonlinear effects in the PIC simulations, including wave breaking and particle-trapping, are found to limit the linear growth phase of the instability for both compressing and non-compressing beams.
[1] Phys. Plasmas 13, 62108 (2006) |
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| THPAN086 | End-to-end Simulations of an Accelerator for Heavy Ion Beam Bunching | 3420 |
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Funding: This research was supported by the U. S. Department of Energy through Princeton Plasma Physics Laboratory and Lawrence Berkeley National Laboratory for the HIFS-VNL. Longitudinal bunching factors in excess of 70 of a 300-keV, 27-mA K+ ion beam have been demonstrated in the Neutralized Drift Compression Experiment in rough agreement with LSP particle-in-cell end-to-end simulations. These simulations include both the experimental diode voltage and induction bunching module voltage waveforms in order to specify the initial beam longitudinal phase space critical to longitudinal compression. To maximize simultaneous longitudinal and transverse compression, we designed a solenoidal focusing system that compensated for the impact of the applied velocity tilt on the transverse phase space of the beam. Here, pre-formed plasma provides beam neutralization in the last one meter drift region where the beam perveance becomes large. Integrated LSP simulations, that include detailed modeling of the diode, magnetic transport, induction bunching module, plasma neutralized transport, were critical to understanding the interplay between the various accelerator components. Here, we compare simulation results with the experiment and discuss the contributions to longitudinal and transverse emittance that limit compression. |
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| THPAN087 | Study of Turn-by-Turn Vertical Beam Dynamics at Low and High Energy CESR Operation | 3423 |
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Funding: This work was supported by the National Science Foundation.
Presently, CESR is operated at two different beam energies, low energy (E=2GeV) for high energy physics (CESR-c), and high energy (E=5.3GeV) for synchrotron radiation production (CHESS). The electron and positron bunches vertical dynamics at these two energies are vastly different, in part due to the change in the pretzel orbit, the presence of wiggler magnets at low energy, and synchrotron radiation power at two vastly different energies. Using the 32 channel photomultiplier array*, we measured the vertical beam dynamics on a turn-by-turn basis during CHESS and CESR-c operation as well as dedicated machine studies time. For these studies we quantify the electron cloud effects such as vertical tune shift and vertical beam size blow-up along the electron and positron trains at these two vastly different beam energies. In addition, the turn-by-turn capability of the PMT array allows us to study the vertical bunch dynamics over 10k turns.
* Design and Implementation of an Electron and Positron Multibunch Turn-by-Turn Vertical Beam Profile Monitor in CESR-PAC2007 proceedings |
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| THPAN088 | Optical Effects of Energy Degraders on the Performance of Fragment Separators | 3426 |
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Funding: This work was supported by the U. S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 An exotic beam facility for the production of rare isotopes requires investigation of higher order optical effects, while taking into account beam-material interactions. An important component of the fragment separator is the absorber wedge, which is necessary for isotope separation. The properties of the absorber, such as the type and shape of material used, determine the resolution and transmission of the fragment separator. Nuclear reactions such as the fission and fragmentation of radioactive isotopes within the target or absorber contribute to the phase space and isotopic distributions of the beam. We have computed these distributions for all isotopes emerging from the target or absorber by implementing a limited fission model from within COSY Infinity that uses polynomial interpolations. Higher order optical aberrations have been computed and successfully eliminated by the shaping of the absorber material. COSY allows us to find the parameters of the absorber that maximize the resolution and transmission of the fragment separator. In addition, beam purity tests have been performed. From our results we have determined an appropriate location for a dump of the primary beam. |
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| THPAN089 | Beam Dynamics, Performance, and Tolerances for Pulsed Crab Cavities at the Advanced Photon Source for Short X-ray Pulse Generation | 3429 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) has decided to implement a system using pulsed* crab cavities to produce short x-ray pulses using Zholents'** scheme. This paper describes beam dynamics issues related to implementation of this scheme in a single APS straight section. Modeling of the cavity is used to demonstrate that the deflection will be independent of transverse position in the cavity. Parameters and performance for a standard and lengthened APS straight section are shown. Finally, tolerances are discussed and obtained from tracking simulations.
* M. Borland et al., these proceedings.** A. Zholents et al., NIM A 425, 385 (1999). |
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| THPAN090 | Fourier Spectral Simulation for Wake Field in Conducting Cavities | 3432 |
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| Recent demand of short-bunch beams poses high-order computational tools for investigating beam dynamics in order to improve the beam quality. We have studied a new computational approach with spectrally accurate high-order approximation for wake field calculations. The technique employs the standard Fourier basis combined with a post-processing procedure for noise reduction by Gegenbauer reconstruction. We integrate this scheme into the existing 2D wake field calculation code ABCI and investigate possible enhancemance of its performance on the same grid base. We will demontrate 2D wake potential simulations for various cylindrically symmetric structures with the quality improvement in comparison to the conventional lower-order method. | ||
| THPAN091 | Spectral-Element Discontinuous Galerkin Simulations for Wake Potential Calculations: NEKCEM | 3435 |
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| The demand for short bunches of 1 ps or less poses not only technical challenges in order to deliver the beams for leading-edge research but also poses computational challenges when it comes to investigating bunched multi-particle beam dynamics in order to improve the beam quality. We introduce a powerful high-order numerical tool based on spetral-element discretizations with discontinuous Galerkin approximation approach, which includes spectral element time domain solver for Maxwell's equation and electrostatic Poisson solver. We will demonstrate 3D simulations for wakefield and wake potential calculations in conducting cavity structures, as well as meshing and visualization components. We will discuss the overcome of the computational bottleneck by widely-used low-order finite difference programs for calculating wake field excited by 1-ps bunches, provided with performance and accuracy comparison. | ||
| THPAN093 | Booster Requirements for Advanced Photon Source 1-nm Emittance Upgrade Lattices | 3438 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 In recent years, we have explored various upgrade options for the Advanced Photon Source (APS) storage ring that would provide the user community higher brightness. Increased brightness would be accomplished by reducing the emittance of the storage ring as well as increasing the stored beam current from 100 mA to 200 mA. Two upgrade lattices were developed that reduce the effective beam emittance to 1 nm from the present 2.7 nm. These lattices have reduced dynamic aperture compared to the present ring lattice, which may require a reduced emittance booster to minimize injection losses. This paper describes injection tracking simulations that explore how high the booster emittance can be and still have no losses at injection for the 1-nm ring upgrade lattices. An alternative booster lattice is presented with reduced emittance compared to the present booster lattice (65 nm). The proposed low-emittance booster lattice would add pole-face windings to the existing booster dipoles and hence would not require replacement of the existing booster magnets. |
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| THPAN094 | Design Study of a Transverse-to-Longitudinal Emittance Exchange Proof-of-principle Experiment | 3441 |
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Funding: Dr. Sun's work is supported by U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. Transverse-to-longitudinal emittance exchange can be achieved through certain arrangements of dipole magnets and dipole mode rf cavity. Theory on such schemes has been developed in the past several years. In this paper we report our numerical simulations on the emittance exchange using particle tracking codes. Photoelectron beams with energy less than 20 MeV are used, as our purpose of simulations is to study the feasibility of performing such emittance exchange at existing facilities of beam energy at this level. Parametric studies of the dipole magnets and cavity strengths, as well as initial beam parameters, are presented. |
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| THPAN095 | Implementation and Performance of Parallelized Elegant | 3444 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The program Elegant* is widely used for design and modeling of linacs for free-electron lasers and energy recovery linacs, as well as storage rings and other applications. As part of a multi-year effort, we have parallelized many aspects of the code, including single-particle dynamics, wakefields, and coherent synchrotron radiation. We report on the approach used for gradual parallelization, which proved very beneficial in getting parallel features into the hands of users quickly. We also report details of parallelization of collective effects. Finally, we discuss performance of the parallelized code in various applications.
*M. Borland, APS Light Source Note LS-287, September 2000. |
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| THPAN096 | A 1-nm Emittance Lattice for the Advanced Photon Source Storage Ring | 3447 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We present a triple-bend lattice design that uses the current APS tunnel. The new lattice has a 1 nm-rad effective emittance at 7 GeV. A forty-period symmetric optics is presented. For the benefit of some X-ray user experiments, an optics with four special straight sections of one-third the beam size of normal sections was investigated as well. The associated nonlinear optical difficulties are addressed and simulation results are presented. |
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| THPAN097 | International Linear Collider Damping Ring Lattice Design | 3450 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We present a lattice design based on the theoretical-minimum-emittance (TME) cell for the International Linear Collider (ILC0 6.6-km 5-GeV damping ring. Several areas are discussed: momentum compaction, lattice layout, injection and extraction, circumference adjusters, phase adjuster, and dynamic aperture calculation with multipole errors. |
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| THPAN098 | Touschek Effect Calculation and Its Application to a Transport Line | 3453 |
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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 Touschek effect is a major concern for lepton storage rings of low emittance (i.e., high bunch density) and low or moderate beam energy, such as third-generation synchrotron light sources. Piwinski's formula, which includes beam shape variation along the beamline and which is suitable for any beam energy, has been incorporated into a program that interoperates with elegant for use in lifetime calculations. The difference between using Piwinski's method and other simplified methods for the APS is shown in this paper. Furthermore, because of the generality of this formula, we also applied it to transport lines to predict beam loss rates and beam loss locations for the first time. An example related to a possible energy recovery linac upgrade of the APS (APS-ERL) is also given in this paper. |
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| THPAN099 | Direct Space-Charge Calculation in Elegant and Its Application to the ILC Damping Ring | 3456 |
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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 direct space-charge force model has been implemented in the tracking code elegant. The user can simulate transverse space-charge effects by inserting space-charge elements in the beamline at any desired position. Application to the International Linear Collider damping ring is presented in this paper. We simulated beam under equilibrium conditions, as well as the entire damping cycle from injection to extraction. Results show that beam halo is generated due to space charge effects. This would be a significant concern for the ILC damping ring and a detailed follow-up study is needed. |
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| THPAN100 | Parallelization of TRACK for Large Scale Beam Dynamic Simulations in Linear Accelerator | 3459 |
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Funding: This work was supported by the U. S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC-02-06CH11357.
Large scale beam dynamics simulations are important to support the design and operations of an accelerator. From the beginning, the beam dynamics code TRACK was developed to make it useful in the three stages of a hadron (proton and heavy-ion) linac project, namely the design, commissioning and operation of the machine. In order to combine the unique features of TRACK with large scale and fast parallel computing we have recently developed a parallel version of the code*. We have successfully benchmarked the parallel TRACK on different platforms: BG/L and Jazz at ANL, Iceberg at ARSC, Lemieux at PSC and Seaborg at NERSC. We have performed large scale RFQ and end-to-end simulations of the FNAL proton driver where particles were simulated. The actual parallel version has the potential of simulating particles on 10 racks with 20,480 processors of BG/L at ANL, which will be available soon. After a brief description of the parallel TRACK, we'll present results from highlight applications.
* "Parallelization of a Beam Dynamics Code and First large Scale RFQ Simulations", J. Xu, B. Mustapha, V. N. Aseev and P. N. Ostroumov, accepted for publication in PRST-AB. |
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| THPAN101 | Parametric Modeling of Transverse Phase Space of an RF Photoinjector | 3462 |
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Funding: DOE PHASE II STTR - DE-FG02-04ER86225 High brightness electron beam sources such as rf photo-injectors as proposed for SASE FELs must consistently produce the desired beam quality. We report the results of a study in which a combined neural network (NN) and first-principles (FP) model is used to model the transverse phase space of the beam as a function of quadrupole magnet current, while beam charge, solenoid field, accelerator gradient, and linac voltage and phase are kept constant. The parametric transport matrix between the exit of the linac section and the spectrometer screen constitutes the FP component of the combined model. The NN block provides the parameters of the transport matrix as functions of quad current. Using real data from SLAC Gun Test Facility, we will highlight the significance of the constrained training of the NN block and show that the phase space of the beam is accurately modelled by the combined NN and FP model, while variations of beam matrix parameters with the quad current are correctly captured. We plan to extend the combined model in the future to capture the effects of variations in beam charge, solenoid field, and accelerator voltage and phase. |
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| THPAN102 | Tevatron Optics Measurements using an AC Dipole | 3465 |
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| The AC dipole is a device that can be used to study beam optics of hadron synchrotrons. It can produce sustained large amplitude oscillations with virtually no emittance growth. A vertical AC dipole for the Tevatron was recently implemented and a maximum oscillation amplitude of 2 (4) σ beam size at 980 (150) GeV was achieved. If such large oscillations are combined with the Tevatron's BPM system (20 micron resolution), not only linear but even nonlinear optics can be measured not depending on machine models. This paper discusses how to make model independent measurements of ring-wide beta functions using the AC dipole and shows test results and comparisons to other methods. The emittance preserving nature of the AC dipole allows multiple measurements on the same beam. By repeating measurements with a small change to the optics every time, the accuracy of measurements using the AC dipole can be determined. Results of such tests are also presented. | ||
| THPAN103 | G4Beamline Simulation Program for Matter-dominated Beamlines | 3468 |
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Funding: Supported in part by DOE STTR grant DE-FG02-06ER86281 G4beamline is a single-particle simulation program optimized for the design and evaluation of beam lines. It is based on the Geant4 toolkit, and can implement accurate and realistic simulations of particle transport in both EM fields and in matter. This makes it particularly well suited for studies of muon collider and neutrino factory design concepts. G4beamline includes a rich repertoire of beamline elements and is intended to be used directly without C++ programming by accelerator physicists. The program has been enhanced to handle a larger class of beamline and detector systems, and to run on Linux, Windows, and Macintosh platforms. |
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| THPAN104 | Coupled Optics Reconstruction from TBT Data using MAD-X | 3471 |
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Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy Turn-by-turn BPM data provide immediate information on the coupledoptics functions at BPM locations. In the case of small deviations from the known (design) uncoupled optics some cognizance of the sources of perturbation, BPM calibration errors and tilts can also be inferred without detailed lattice modelling. In practical situations, however, fitting the lattice model with the help of some optics code would lead to more reliable results. We present an algorithm for coupled optics reconstruction from TBT data on the basis of MAD-X and give examples of its application for the Fermilab Tevatron and Booster accelerators. |
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| THPAN105 | Effects of Space Charge and Magnet Nonlinearities on Beam Dynamics in the Fermilab Booster | 3474 |
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Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy Presently the Fermilab Booster can accomodate about half the maximum proton beam intensity which the Linac can deliver. One of the limitations is related to large vertical tuneshift produced by space-charge forces at injection energy. In the present report we study the nonlinear beam dynamics in the presence of space charge and magnet imperfections and analyze the possibility of space charge compensation with electron lenses. |
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| THPAN106 | 6D Ionization Cooling Channel with Resonant Dispersion Generation | 3477 |
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Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy For muons with preferable for ionization cooling momentum <300MeV/c the longitudinal motion is naturally undamped. In order to provide the longitudinal damping a correlation between muon momentum and transverse position - described in terms of the dispersion function - should be introduced. In the present report we consider the possibility of dispersion generation in a periodic sequence of alternating solenoids (FOFO channel) by choosing the tune in the second passband (i.e. above half-integer per cell) and tilting the solenoids in adjacent cells in the opposite direction. Analytical estimates as well as simulation results for equilibrium emittances and cooling rates are presented. |
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| THPAN108 | TBT Optics and Impedance Measurements at the Fermilab Main Injector | 3480 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000. The Main Injector (MI) is a rapid cycling multipurpose accelerator. After completion of the Tevatron Run II, its primary application will be the acceleration of high intensity proton beams for neutrino experiments. To achieve the intensity goal a detailed knowledge of the optics and transverse impedances is necessary which can be obtained from Turn-By-Turn (TBT) beam position measurements. The recent MI Beam Position Monitor system upgrade made it possible to apply the TBT data analysis methods which were successfully used by the authors for the Tevatron. We present the results of MI optics measurements and the impedance estimates obtained from the betatron phase advance dependence on beam current. |
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| THPAN109 | A New Lattice Design for a 1.5 TeV CoM Muon Collider Consistent with the Tevatron Tunnel | 3483 |
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| A recent effort is underway to design an efficient match of a Muon Collider to the Fermilab site, potentially using the Tevatron tunnel after decommissioning. This work represents a new design for such a collider with emphasis on shortened IR and systematic high-order correction and dynamics studies. With a 1 cm β*, simultaneous control of geometric and chromatic aberrations is critical and can only be achieved through the deliberate addition of nonlinear fields in the Interaction Region itself. This work studies both the correction schemes and the unavoidable impact of high-order correctors – sextupoles, octupoles and even duodecapoles – located in the Interaction Region close to the low-beta quadrupoles or focusing elements. This study proposes and systematically addresses the aberrations for different systems of nonlinear correctors and optimizes performance of an advanced IR. | ||
| THPAN112 | CHEF: A Status Report | 3486 |
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Funding: Authored by Universities Research Association, Inc. under contract No. DE-AC02-76CH03000 with the U. S. Department of Energy. CHEF is both a framework and an interactive application emphasizing accelerator optics calculations. The framework supports, using a common infrastructure, multiple domains of applications: e.g. nonlinear analysis, perturbation theory, and tracking. Its underlying philosophy is to provide infrastructure with minimum hidden implicit assumptions, general enough to facilitate both routine and specialized computational tasks and to minimize duplication of necessary, complex bookkeeping tasks. CHEF was already described in recent conferences. In this paper we present a status report on the most recent developments, including issues related to its application to high energy linacs. |
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| THPAN113 | Mxyzptlk: An Efficient, Native C++ Differentiation Engine | 3489 |
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Funding: Authored by Universities Research Association, Inc. under contract No. DE-AC02-76CH03000 with the U. S. Department of Energy. Mxyzptlk was one of the early and, to this day, limited number of differentiation engines implemented by taking full advantage of a language with operator overloading capabilities. It was created with an eye at enabling accelerator related computations, especially within the realm of perturbation theories. Such computations are supported by (1) a one-to-one correspondence between original mathematical abstractions and the data types and operations used to implement them; (2) the exact computation of high order derivatives. Significant efforts were invested recently in modernizing Mxyzptlk both architecturally and algorithmically. Among other things, these substantially improved performance and usabilty. We present a description of the current Mxyzptlk from both standpoints and describe its current capabilities and performance. |
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| THPAN114 | Simulations of Beam-wire Experiments at RHIC | 3492 |
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| We report on simulations of beam-beam experiments performed at RHIC in 2006. These experiments were designed to observe the influence of a single parasitic interaction on beam quality. Several observables such as tunes, emittances and losses were simulated with the weak-strong code BBSIM. These simulation results are compared to observed values. Simulations of the wire compensation experiment to be carried out in RHIC are also shown. | ||
| THPAN115 | Direct Measurements of Beta-star in the Tevatron | 3495 |
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Funding: Work supported by the U. S. Department of Energy under contract No. DE-AC02-76CH03000. Until recently, values of the amplitude functions through the Interaction Regions of the Tevatron collider detectors have been inferred either by reconstructing event locations through the detector and mapping out the luminous region to deduce the beam emittance and amplitude function or by performing differential closed orbit measurements while varying steering magnets and producing detailed models of the synchrotron's optical properties which reproduce the observed orbital deviations. Both of these methods rely on often lengthy off-line analyses and sometimes many hours of experimental data to obtain a meaningful result. The new Tevatron Beam Position Monitor system, commissioned in 2005, has allowed unprecedented detail of turn-by-turn motion to be measured at the 20-micron level and for thousands of beam revolutions. Such measurements performed with a freely oscillating proton beam, excited by a kicker magnet, allow for the direct measurement of the amplitude function which is model independent. A simple measurement procedure, data analysis method, and typical results for the Tevatron experimental regions are presented. |
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| THPAN116 | Lattice Measurement for Fermilab Main Injector | 3498 |
| The installation of seven large aperture quadrupoles during the shut-down of 2006 necessitates new measurements to ascertain the state of machine lattice, both at injection and at extraction. These new quadrupoles replaced existing quadrupoles at each of the seven injection/extraction locations around the Fermilab Main Injector. Though extensive magnet measurement had been made the effect of trim coils used to compensate differences in magnet characteristics has to be verified. The result of lattice analysis and others will be discussed. | ||
| THPAN117 | Electron Cloud Studies at Tevatron and Main Injector | 3501 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000 Estimates indicate that the electron cloud effect could be a limiting factor for Main Injector intensity upgrades, with or without a the presence of a new 8 GeV superconducting 8GeV Linac injector. The effect may turn out to be an issue of operational relevance for other parts of the Fermilab accelerator complex as well. To improve our understanding of the situation, two sections of specially made vacuum test pipe outfitted for electron cloud detection with ANL provided Retarding Field Analyzers (RFAs), were installed in the Tevatron and the Main Injector. In this report we present some measurements, compare them with simulations and discuss future plans for studies. |
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| THPAN118 | Simulations of the Electron Cloud Buildups and Suppressions in Tevatron and Main Injector | 3504 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000 To assess the effects of the electron cloud on Main Injector intensity upgrades, simulations of the cloud buildup were carried out using POSINST and compared with ECLOUD. Results indicate that even assuming an optimistic 1.3 maximum secondary electron yield, the electron cloud remains a serious concern for the planned future operational of mode of 500 bunches, 3·1011 proton per bunch. Electron cloud buildup can be mitigated in various ways. We consider a plausible scenario involving solenoids in straight section and a single clearing strip electrode (like SNEG in Tevatron)held at a potential of 500V. Simulations with parameters corresponding to Tevatron and Main Injector operating conditions at locations where special electron cloud detectors have been installed have been carried out and are in satisfactory agreement with preliminary measurements. |