| Paper | Title | Other Keywords | Page | ||
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| MPPE047 | Optics Flexibility and Matching at LHC Injection | optics, injection, quadrupole, emittance | 2983 | ||
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An excellent match between the SPS, the several kilometers long transfer lines and the LHC will be required to minimise emittance blow-up at injection. Several optics changes in the SPS and the LHC injection insertions had to be accommodated in the design phase. The new 3-phase collimation system in the transfer lines results in additional phase advance constraints. It will be important to maintain some tuning range for the LHC commissioning phase and to accommodate possible further optics changes. We analyse the requirements, the constraints, the current status and options to enhance the optics flexibility.
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| MPPE048 | Beam Based Alignment of the LHC Transfer Line Collimators | beam-losses, injection, simulation, proton | 3034 | ||
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At LHC injection energy the aperture available in the transfer lines and in the LHC is small and the intensities of the injected beams are an order of magnitude above the damage level. The setting of protection elements such as the transfer line collimators is therefore very critical; mechanical and optical tolerances must be taken into account to define the nominal setting. Being able to measure and control the collinearity of the collimator jaws with the beam relaxes the requirement on the settings considerably. A method to measure angular misalignment of the collimator jaws in the transfer line based on a transmission measurement is discussed. Simulations have been made and are compared with the results of an alignment test performed with beam during the 2004 commissioning of the transfer line TI 8.
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| MPPE060 | Quadrupole Beam-Based Alignment at RHIC | quadrupole, injection, optics, heavy-ion | 3493 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy |
Successful implementation of a beam-based alignment algorithm, tailored to different types of quadrupoles at RHIC, provides significant benefits to machine operations for heavy ions and polarized protons. This algorithm is used to calibrate BPM centers relative to interaction region (IR) quadrupoles to maximize aperture. It is also used to determine the optimal orbit through transition jump quadrupoles to minimize orbit changes during the transition jump for heavy ion acceleration. This paper provides background discussion and results from first application during the RHIC 2005 run. |
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| MPPT025 | Field Quality and Magnetic Center Stability Achieved in a Variable Permanent Magnet Quadrupole for the ILC | quadrupole, permanent-magnet, multipole, linear-collider | 1913 | ||
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Funding: Work supported in part by Department of Energy contract DE–AC03–76SF00515 and by the Ministry of Education, Science, Sports and Culture, Japan, Grant-in-Aid for Scientific Research (A) 14204023. |
The precise tolerances on the last two quadrupoles before the interaction point of the proposed, superconducting e+e- collider (ILC) have not been determined yet. These quads will be aligned with a beam-based alignment (BBA) process during which their integrated strengths will be decreased by 20%. Their magnetic centers must move by less than a few microns during the BBA else a systematic error will be introduced, yielding an increase in the beam spot size. These strong quads must be small to fit in the tight space. A compact, variable, superstrong permanent magnet quad (PMQ) has been fabricated and tested. The PMQ has inner and outer rings of NEOMAX; the outer ring is subdivided along its length and each section can rotate. By rotating different lengths one can vary the integrated strength in small steps. Because of the fixed inner ring and tight mechanical tolerances, the sensitivities of the magnetic center and pole angles to the rotation of the outer rings are largely suppressed. Measurements of the PMQ will be presented, plus how observed small center and angle shifts were further reduced by adjustments to the stopping angles of the rotating rings and by shimming these rings. |
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| MPPT029 | Performance of an Adjustable Strength Permanent Magnet Quadrupole | quadrupole, permanent-magnet, linear-collider, collider | 2071 | ||
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Funding: Department of Energy Grant DE-FG03-01ER83305. |
An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic centerline and field quality made using an air bearing rotating coil system. The magnetic centerline stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic centerline. Calibration procedures as well as centerline measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported. |
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| MPPT041 | Improvement of the Geometrical Stability of the LHC Cryodipoles when Blocking the Central Support Post | dipole, vacuum, superconducting-magnet, laser | 2675 | ||
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The LHC will be composed of 1232 horizontally curved 16 meter long super-conducting dipole magnets cooled at 1.9K, supported within their vacuum vessel by three Glass Fiber Resin Epoxy (GFRE) support posts. The two support posts at the dipole extremities were initially designed free to slide longitudinally with respect to the vacuum vessel and the central support post was designed free to slide transversally. However the magnet shape did not retain the tight geometrical tolerances, of the order of fractions of mm, imposed by machine aperture and magnetic corrector centering requirements. Thereafter a modification to the supporting system, removing the initial transversal degree of freedom of the lower flange of the central support post with respect to the vacuum vessel, was designed and implemented. This paper describes the design of the magnet/cryostat interface with and without blockage of the central support post, analyzes the additional mechanical loads related to the modification and reviews the experimental results with respect to the requirements for beam aperture and magnetic corrector centering.
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| MPPT042 | Field Quality and Alignment of the Series Produced Superconducting Matching Quadrupoles for the LHC Insertions | quadrupole, multipole, insertion, dipole | 2738 | ||
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The production of the superconducting quadrupoles for the LHC insertions is advancing well and about half of the magnets have been produced. The coil size and field measurements performed on individual magnets both in warm and cold conditions are yielding significant results. In this paper we present the procedures and results of steering the series production at the magnet manufacturers and the assembly of cold masses at CERN. In particular, we present the analysis of warm-cold correlations and hysteresis of the main field multipoles, the correlation between coil sizes and geometrical field errors and the effect of permeability of magnet collars. The results are compared with the target errors for field multipoles and alignment.
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| MPPT066 | Pulsed Undulator for Polarized Positron Production | undulator, positron, power-supply, photon | 3676 | ||
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We represent here elements of design and results of testing for helical undulator with ~2.5-mm period, manufactured in Cornell LEPP for polarized positron production at SLAC. At 2.3 kA undulator reaches K~0.2 and operated up 30 Hz.
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| MPPT080 | Design, Fabrication and Characterization of a Large-Aperture Quadrupole Magnet for CESR-c | quadrupole, luminosity, photon, focusing | 4063 | ||
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Funding: National Science Foundation. |
Installation of a radiative Bhabha luminosity monitor for CESR-c operation in 2004 required replacing a 40-mm aperture steel quadrupole magnet with one of aperture 75 mm, while maintaining field-quality tolerances at the level of a few parts in $104. We present the design methodology using 2D- and 3D-finite-element field calculations, compare the calculated 3D integrals to flip-coil measurements, and discuss related mechanical tolerances. |
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| TOAA002 | U.S. Accelerator Contribution to the LHC | quadrupole, dipole, luminosity, interaction-region | 184 | ||
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In 1998, the United States entered into an agreement with CERN to help build the Large Hadron Collider (LHC), with contributions to the accelerator and to the large HEP detectors. To accomplish this, the US LHC Accelerator Project was formed, encompassing expertise from Brookhaven National Laboratory, Fermi National Accelerator Laboratory and the Lawrence Berkeley National Laboratory. Contributions from the US LHC Accelerator project included superconducting high gradient quadrupoles and beam separation dipoles for the four interaction regions and the RF section; feedboxes for cryogenic, power and instrumentation distribution; neutral and hadron beam absorbers in the high luminosity regions; design of the inner triplet cryogenic system; beam tracking studies utilizing the design IR magnet field quality and magnet alignment; particle heat deposition studies in the IR’s; and short sample characterization of superconducting cables used in the arc dipoles and quadrupoles. This report is a summary of these contributions including the progress towards project completion, as well as a discussion of future plans for US participation in the LHC accelerator.
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| TOAA004 | Field Quality Study in Nb3Sn Accelerator Magnets | sextupole, dipole, quadrupole | 366 | ||
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Funding: This work was supported by the U.S. Department of Energy. |
High field accelerator magnets are being developed at Fermilab for present and next generation hadron colliders. These magnets are designed for a nominal field of 10-12 T in the magnet bore of 40-50 mm and an operating temperature of 4.5 K. To achieve these design parameters, a new, high-performance Nb3Sn superconducting strand is used. Four short Nb3Sn dipole models of the same design based on a single-bore cos-theta coil and a cold iron yoke have been fabricated and tested at Fermilab. Their field quality was measured at room temperature during magnet fabrication and at helium temperature. This paper reports the results of warm and cold magnetic measurements. The systematic geometrical harmonics and their RMS spread due to cross-section imperfections, the coil magnetization effects caused by persistent currents in superconductor and eddy current in the cable, the "snap-back" effect at injection and the iron saturation effect at high fields are presented and compared with theoretical predictions. |
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| TOAA006 | Development of Superconducting Combined Function Magnets for the Proton Transport Line for the J-PARC Neutrino Experiments | dipole, proton, quadrupole, target | 495 | ||
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A second generation of long-baseline neutrino oscillation experiments has been proposed as one of the main projects at J-PARC jointly built by JAERI and KEK. Superconducting combined function magnets, SCFMs, will be utilized for the 50 GeV, 750 kW proton beam line for the neutrino experiment and an R&D program is in underway at KEK. The magnet is designed to provide a combined function of a dipole field of 2.6 T with a quadrupole field of 19 T/m in a coil aperture of 173.4 mm. A series of 28 magnets in the beam line will be operated DC in supercritical helium cooling below 5 K. A design feature of the SCFM is the left-right asymmetry of the coil cross section: current distributions for superimposed dipole- and quadrupole- fields are combined in a single layer coil. Another design feature is the adoption of glass-fiber reinforced phenolic plastic spacers to replace the conventional metallic collars. To evaluate this unique design, fabrication of full-scale prototype magnets is in progress at KEK and the first prototype will be tested at cold soon. This paper will report the development of the SCFMs.
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| TPAP016 | Energy Calibration of the SPS with Proton and Lead Ion Beams | proton, sextupole, ion, quadrupole | 1470 | ||
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The momentum of the 450 GeV/c proton beam of the CERN Super Proton Synchrotron was determined by a high precision measurement of the revolution frequencies of proton and lead ion beams. To minimize systematic errors the magnetic cycle of the SPS had to be rigorously identical for both beams, and corrections due to Earth tides had to be taken into account. This paper presents how the beam momentum was determined from the RF frequency for which the beams are centred in the machine sextupoles. The measured beam momentum is 449.16 ± 0.14 GeV/c for a nominal momentum of 450 GeV/c, and the accuracy is limited by systematic errors.
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| TPAP017 | Beam Stability of the LHC Beam Transfer Line TI8 | extraction, proton, injection, septum | 1523 | ||
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Injection of beam into the LHC at 450 GeV/c proceeds over two 2.7 km long transfer lines from the SPS. The small aperture of the LHC at injection imposes tight constraints on the stability of the beam transfer. The first transfer line TI8 was commissioned in the fall of 2004 with low intensity beam. Since the beam position monitor signal fluctuations were dominated by noise with low intensity beam, the beam stability could not be obtained from a simple comparison of consecutive trajectories. Instead model independent analysis (MIA) techniques as well as scraping on collimators were used to estimate the intrinsic stability of the transfer line. This paper presents the analysis methods and the resulting stability estimates.
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| TPAP019 | Aperture Studies of the SPS to LHC Transfer Lines | optics, simulation, dipole, injection | 1664 | ||
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The SPS to LHC transfer lines TI 2 and TI 8 are each several km in length and use magnets with small apertures. An aperture model for the lines has been developed in MAD-X format, with a full description of all installed vacuum elements and the possibility to interpolate at any length interval. This model has been used with tolerances and errors to simulate the expected line aperture available for the beam. The model features and simulation results are presented, with derived aperture limits. The results from aperture measurements made during the TI 8 line beam commissioning in 2004 are presented and compared to the expectations.
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| TPAP027 | Deterioration of the Skew Quadrupole Moment in Tevatron Dipoles Over Time | quadrupole, coupling, dipole, monitoring | 1967 | ||
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Funding: United States Department of Energy under Contract No. DE-AC02-76CH03000. |
During the 20 years since it was first commissioned, the Fermilab Tevatron has developed strong coupling between the two transverse degrees of freedom. A circuit of skew quadrupole magnets is used to correct for coupling and, though capable, its required strength has increased since 1983 by more than an order of magnitude. In more recent years changes to the Tevatron for colliding beams operation have altered the skew quadrupole corrector distribution and strong local coupling become evident, often encumbering routine operation during the present physics run. Detailed magnet measurements were performed on each individual magnet during construction, and in early 2003 it was realized that measurements could be performed on the magnets in situ which could determine coil movements within the iron yoke since the early 1980's. It was discovered that the superconducting coils had become vertically displaced relative to their yokes since their construction. The ensuing systematic skew quadrupole field introduced by this displacement accounts for the required corrector settings and observed beam behavior. An historical account of the events leading to this discovery and progress toward its remedy are presented. |
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| TPAP030 | Tevatron Alignment Issues 2003-2004 | dipole, quadrupole, closed-orbit, laser | 2146 | ||
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Funding: U.S. Department of Energy under contract No. DE-AC02-76CH03000. |
It was observed during the early part of Run II that dipole corrector currents in the Tevatron were changing over time. Measurement of the roll for dipoles and quadrupoles confirmed that there was a slow and systematic movement of the magnets from their ideal position. A simple system using a digital protractor and laptop computer was developed to allow roll measurements of all dipoles and quadrupoles. These measurements showed that many magnets in the Tevatron had rolled more than 1 milli-radian. To aid in magnet alignment a new survey network was built in the Tevatron tunnel. This network is based on the use of free centering laser tracker. During the measurement of the network coordinates for all dipole, quadrupole and corrector magnets were obtained. This paper discusses roll measurement techniques and data, the old and new Tevatron alignment network. |
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| TPPP033 | Cavity Alignment Using Beam Induced Higher Order Modes Signals in the TTF Linac | dipole, single-bunch, linac, higher-order-mode | 2284 | ||
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Funding: DE-AC02-76SF00515. |
Each nine cell superconducting accelerator cavity in the TESLA Test Facility (TTF) at DESY* has two higher order mode (HOM) couplers that efficiently remove the HOM power.** They can also provide useful diagnostic signals. The most interesting modes are in the first 2 cavity dipole passbands. They are easy to identify and their amplitude depends linearly on the beam offset from the cavity axis making them excellent beam position monitors (BPM). By steering the beam through an eight-cavity cryomodule, we can use the HOM signals to estimate internal residual alignment errors and minimize wakefield related beam emittance growth. We built and commissioned a four channel heterodyne receiver and time-domain based waveform recorder system that captures information from each mode in these two bands on each beam pulse. In this paper we present an experimental study of the single-bunch generated HOM signals at the TTF linac including estimates of cavity alignment precision and HOM BPM resolution. *P. Piot, DESY-TESLA-FEL-2002-08. **R. Brinkmann et al. (eds.), DESY-2001-011. |
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| TPPT017 | Fabrication and Test of the Drift Tubes for PEFP 20 MeV DTL | vacuum, electron, proton, site | 1552 | ||
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Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government. |
Drift tubes of PEFP (Proton Engineering Frontier Project) 20MeV DTL contain electro-quadrupole magnet composed of commercial enamel wire cooled with water coolant. Those were fabricated through the process of brazing, assembling, electron-beam welding, and post-machining. During the e-beam welding, temperature increase was kept under 50 degree to protect the EQM wire from thermal damage. We performed several tests such as vacuum leak test, hydraulic test, and electrical test. EQM properties such as effective length, magnetic saturation, and offset between magnetic center and geometric center of DT were measured and recorded also. |
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| TPPT044 | Beam Position Monitoring Using the HOM-Signals from a Damped and Detuned Accelerating Structure | linac, linear-collider, collider, dipole | 2804 | ||
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Funding: Work Supported by DOE Contract DE-AC02-76F00515. |
The Next Linear Collider (NLC) and Global Linear Collider (GLC) designs require precision beam-to-accelerator-structure alignment to reduce the effect of short range wakefields. For this purpose, the HOM signals from the structure dipole mode damping ports would be used to determine the beam position in the structure, and then the structures would be moved remotely to center them about the beam (a 5 micron rms alignment is required). In 2000, a test of a 1.8 m prototype structure in the ASSET facility at SLAC achieved 11 micron rms centering accuracy, which was limited by systematic effects caused by beam jitter. This year, such measurements were repeated for a pair of shorter structures (60 cm) that were developed to improve high gradient performance. In addition, the beam position resolution was determined by measuring simultaneously three signal frequencies (14.3, 15, 15.7 GHz) corresponding to modes localized at the beginning, the middle and the end of the structures. In this paper, we present results from the beam centering and position resolution measurements. |
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| TPPT052 | Cryogenic, Magnetic and RF Performance of the ISAC-II Medium Beta Cryomodule at TRIUMF | acceleration, target, coupling, ion | 3191 | ||
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The medium beta section of the ISAC-II Heavy Ion Accelerator consists of five cryomodules each containing four quarter wave resonators and one superconducting solenoid. The first cryomodule has been designed, assembled and cold tested at TRIUMF. The cryomodule vacuum space shares the cavity vacuum and contains a mu-metal shield, an LN2 cooled, copper thermal shield, plus the cold mass and support system. The bulk niobium cavities are fitted with an LN2 cooled coupling loop fed in series from the side thermal shield and a tuner plate coupled to an out-of-vacuum linear servo motor. All cavities have been locked at the ISAC-II frequency and gradient for extended periods. This paper will report the cryogenic and rf test results from the three cold tests. Of note are measurements of the magnetic field in the cryomodule and estimations of changes in the magnetic field during the test due to trapped flux in the solenoid and magnetization of the environment.
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| TPPT053 | Low-Beta SC Quarter-Wave Resonator and Cryomodule for SPIRAL 2 | linac, vacuum, simulation, injection | 3238 | ||
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In the framework of the SPIRAL 2 project to be built in GANIL, we studied a complete cryomodule for the low beta (0.07) superconducting linac. The 88 MHz quarter wave resonators were optimised for RF, mechanical and thermal considerations. A prototype resonator, which differs from the final resonator by the Helium tank and the removable end-plate geometry and material, has been built. We present the equipments developped for the preparation of this prototype as well as the results of the RF tests. We also detail the mechanical calculation and measurements of the tuning system, and the main aspects of the cryomodule designed to save longitudinal space.
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| TPPT094 | Design of the CW Cornell ERL Injector Cryomodule | emittance, linac, higher-order-mode, damping | 4290 | ||
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Funding: This work is supported by Cornell University. |
The Cornell ERL Prototype injector will accelerate bunches from an electron source to an energy of several MeV, while preserving the ultra-low emittance of the beam. The injector linac will be based on superconducting RF technology with five 2-cell RF cavities operated in cw mode. The beam tubes on one side of the cavities have been enlarged to propagate Higher-Order-Mode power from the cavities to broadband RF ring-absorbers located at 80 K between the cavities. The axial symmetry of these ferrite based absorbers, together with two symmetrically placed input couplers per cavity, avoids transverse on-axis fields, which would cause emittance growth. Each cavity is surrounded by a LHe vessel and equipped with a frequency tuner. The cryomodule provides the support and alignment for the cavity string, the LN cooling of the ferrite loads, and the 2K LHe cryogenic system for the high cw heat load of the cavities. In this paper we give an overview of the ERL injector cryomodule design. |
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| TPPT096 | Cryomodule Design for a Superconducting Linac with Quarter-Wave, Half-Wave, and Focusing Elements | quadrupole, vacuum, linac, focusing | 4317 | ||
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The low-energy section of the driver linac for the proposed Rare Isotope Accelerator (RIA) incorporates the following superconducting elements: quarter-wave resonators, half-wave resonators, and 9 T solenoids. A prototype cryomodule has been designed to house all of these elements. A 31 T/m superferric quadrupole is also included as an alternative focusing element, since its stray magnetic field is more easily shielded. The cryomodule design is based on the RIA v/c=0.47 prototype cryomodule that was successfully tested in 2004.* The design uses a titanium rail structure to support the beam line elements. The beam line assembly is done in a class 100 clean room to maintain resonator cleanliness for optimal high-field performance. The cavities will be equipped with RF input couplers, tuners, and magnetic shields. High Tc current leads are used for both magnets. The cryomodule design takes into account static heat leak requirements and alignment tolerances for the beam line elements. A heat exchanger and J-T throttle valve will be used to provide a continuous supply of liquid helium for 2 K operation.
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*T.L. Grimm et al., "Experimental Study of an 805 MHz Cryomodule for the Rare Isotope Accelerator", in Proceedings of the XXII International Linear Accelerator Conference, Lubeck, Germany (2004). |
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| WPAE036 | Harmonic Analysis of Linac Alignment | linac, focusing, lattice, laser | 2431 | ||
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Funding: Work conducted at Los Alamos National Laboratory, which is operated by the University of California for the United States Department of Energy under contract W-7405-ENG-36. |
We have analyzed the requirements on alignment of the focusing elements (quadrupole doublets) in the Los Alamos Neutron Science Center (LANSCE) side coupled linac. The analysis is performed in terms of harmonics of the quardrupole spacing. This allows us to determine the effect of intentional deviations from a straight line, such as following the curvature of the Earth, and of unintentional deviations introduced by measurement and alignment errors. Results are compared to measured positions of the doublets. |
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| WPAE037 | Deformation Monitoring of the Spallation Neutron Source (SNS) Tunnels | monitoring, SNS, survey, target | 2509 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
The SNS Project is a 1.4 MW accelerator-based neutron source located at Oak Ridge National Laboratory in Oak Ridge, Tennessee. For shielding purposes, a 17 foot berm of native soil has been constructed on top of the accelerator tunnel system. This backfill has caused ongoing settlement of the tunnels. The settlement has been monitored by the SNS Survey and Alignment Group at regular intervals, in order to discover the patterns of deformation, and to determine when the tunnels will be stable enough for precise alignment of beam line components. The latest monitoring results indicate that the settlement rate has significantly decreased. This paper discusses the techniques and instrumentation of the monitoring surveys, and provides an analysis of the results. |
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| WPAE039 | Optical Tooling and its Uses at the Spallation Neutron Source (SNS) | target, SNS, laser, instrumentation | 2577 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
Optical tooling has been a mainstay of the accelerator alignment community for decades. Even now in the age of electronic survey equipment, optical tooling remains a viable alternative, and at times the only alternative. At SNS, we combine traditional optical tooling alignment methods, instrumentation, and techniques, with the more modern electronic techniques. This paper deals with the integration of optical tooling into the electronic survey world. |
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| WPAE043 | Alignment of the Booster Injector for the Duke Free Electron Laser Storage Ring | booster, laser, storage-ring, dipole | 2786 | ||
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Funding: This work is supported by U.S. Department of Energy grant DE-FG02-01ER41175 and by U.S. AFOSR MFEL grant F49620-001-0370. |
This paper presents the methodology and initial results for mechanical alignment of the booster synchrotron for the Duke FEL storage ring. The booster is a compact design and requires special considerations for alignment. The magnetic and vacuum elements of the arcs have been designed for alignment by a laser tracker system. A parametric 3D design package has been used to determine target coordinates. These target coordinates evolve from design goals to physically verified dimensions by modifying the parametric model to match mechanical measurement data after fabrication. By utilizing the functionality of the laser tracker system and a parametric 3D modeler, a direct and efficient measurement and alignment technique has been developed for a complex geometry. |
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| WPAE044 | An Alignment of J-PARC Linac | linac, target, synchrotron, survey | 2851 | ||
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J-PARC linear accelerator components are now being installed in the accelerator tunnel, whose total length is more than 400 m including the beam transport line to RCS (Rapid Cycling Synchrotron). A precise alignment of accelerator components is essential for a high quality beam acceleration. In this paper, planned alignment schemes for the installation of linac components, the fine alignment before beam acceleration, and watching the long term motion of the building are described. Guide points are placed on the floor, which acts as a reference for the initial alignment at the installation and also as a relay point for the long surveying network linking at the fine alignment. For a straight line alignment, the wire position sensor is placed on the offset position with respect to the beam center by a target holder, then a single wire can cover the accelerator cavities and the focusing magnets at the DTL-SDTL section (120m). The hydrostatic levering system (HLS) is used for watching the floor elevation (changes) over the long period.
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| WPAE061 | LC Filter for High Accuracy and Stability Digital MPS at PLS | power-supply, simulation, feedback, damping | 3550 | ||
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Funding: Work supported by the Ministry of Science and Technology, Korea. |
High accuracy and stability digital power supply for magnet is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second consists of IGBT driver and four quad IGBT switch, and the third is LC output section. AC input voltage of power supply is 3-phase 21V, output current is 0 ~ 150 A dc. Switching frequency of IGBT is 25 kHz. The output current of power supply has very high accuracy of 100 mA step resolution at full range and the stability of ± 1.5 ppm for short term and ± 5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies. |
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| WPAE082 | Design of a Precision Positioning System for the Undulators of the Linac Coherent Light Source | undulator, quadrupole, laser, vacuum | 4099 | ||
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A precision positioning system has been designed for the Linac Coherent Light Source (LCLS) and a prototype system is being fabricated. The LCLS will use a beam based alignment technique to precisely align all of the segments of the 130-m long undulator line. The requirement for overlap between the electron beam and the x-ray beam, in order to develop and maintain lasing, demands that each of the quadrupoles be aligned within a tolerance of ± 2 μm and that the undulator axis be positioned within ± 10 μm vertically and horizontally. Five cam movers, each with an eccentricity of 1.5 mm, will allow adjustment of a cradle supporting the undulator, its vacuum chamber, a quadrupole, and a beam position monitor. An additional motion transverse to the beam axis allows removal of individual undulators from the beam path. Positioning feedback will be provided by a wire position monitor system and a hydrostatic leveling system.
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| WPAP005 | Beam-Based Procedures for RF Guns | laser, gun, cathode, electron | 967 | ||
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A wide range of rf photo injector parameters has to be optimized in order to achieve an electron source performance as required for linac based high gain FELs. Some of the machine parameters can not be precisely controlled by direct measurements, whereas the tolerance on them is extremely tight. Therefore, this should be met with beam-based techniques. Procedures for beam-based alignment (BBA) of the laser on the photo cathode as well as solenoid alignment have been developed. They were applied at the Photo Injector Test facility at DESY Zeuthen (PITZ) and at the photo injector of the VUV-FEL at DESY Hamburg. A field balance of the accelerating mode in the 1 ½ cell gun cavity is one of the key beam dynamics issues of the rf gun. Since no direct field measurement in the half and full cell of the cavity is available for the PITZ gun, a beam-based technique to determine the field balance has been proposed. A beam-based rf phase monitoring procedure has been developed as well.
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| RPAP002 | A CW RFQ Accelerator for Deuterons | rfq, simulation, vacuum, injection | 794 | ||
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Funding: BMBF |
A four-rod RFQ accelerator is being built to accelerate deuterons from 20 keV to 3 MeV. At an operating frequency of 176 MHz the length is 3.8 m and the power consumption 250 kW, the beam current 5 mA. A special feature is the CW-mode operation. The status of the project and properties of the RFQ will be discussed. |
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| RPAP034 | Use Recirculator "SALO" in the Mode of the Neutron Source | target, electron, injection, emittance | 2354 | ||
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The opportunity of use developed in NSC KIPT recirculator SALO* with superconducting accelerating structure TESLA for reception of intensive neutron streams surveyed. As an injector it is supposed to use RF-gun with superconducting accelerating structure. An electron beam with the peak energy 130 ??? is transported on a target located apart of 100 m from recirculator. System of the focusing are designed allowing to gain on a target the required density of a beam. Tolerances on precision of an alignment of magnetooptical devices are calculated.
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*I. S. Guk, A. N. Dovbnya, S. G. Kononenko, A. S. Tarasenko, M. van der Wiel, J. I. M. Botman, NSC KIPT Accelerator on Nuclear and High Energy Physics, Proceedings of EPAC 2004, Lucerne, Switzerland, p.761-764. |
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| RPAP043 | Beam-Based Alignment in the RHIC eCooling Solenoids | ion, quadrupole, electron, proton | 2771 | ||
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Funding: U.S. DOE. |
Accurate alignment of the electron and ion beams in the RHIC electron cooling solenoids is crucial for well-optimized cooling. Because of the greatly differing rigidities of the electron and ion beams, to achieve the specified alignment accuracy it is required that transverse magnetic fields resulting from imperfections in solenoid fabrication be down by five orders of magnitude relative to the pure solenoid fields. Shimming the solenoid field to this accuracy might be accomplished by survey techniques prior to operation with beam, or by methods of beam-based alignment. We report on the details of a method of beam-based alignment, as well as the results of preliminary measurements with the ion beam at RHIC |
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| RPAT028 | RHIC BPM System Modifications and Performance | injection, radiation, quadrupole, instrumentation | 2021 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy. |
The RHIC beam position monitor (BPM) system provides independent average orbit and turn-by-turn (TBT) position measurements. In each ring, there are 162 measurement locations per plane (horizontal and vertical) for a total of 648 BPM planes in the RHIC machine. During 2003 and 2004 shutdowns, BPM processing electronics were moved from the RHIC tunnel to controls alcoves to reduce radiation impact, and the analog signal paths of several dozen modules were modified to eliminate gain-switching relays and improve signal stability. This paper presents results of improved system performance, including stability for interaction region and sextupole beam-based alignment efforts. We also summarize performance of improved million-turn TBT acquisition channels for nonlinear dynamics and echo studies. |
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| RPAT082 | Coherent Transition Radiation To Measure the SLAC Electron Bunch Length | electron, radiation, background, laser | 4102 | ||
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Funding: Work supported by U.S. DOE. |
Ultrashort electron bunches are now available at Stanford Linear Accelerator Center and are use mainly to produce short bursts of x-rays in a magnetic undulator and for plasma wakefield acceleration experiments. The shortest bunches have an rms longitudinal width of ˜10 microns, and a peak current of about 30 kA. Methods to measure such short bunch lengths include electro-optic modulation of a short laser pulse in a nonlinear crystal and coherent transition (CTR) autocorrelation. The transition radiation spectrum emitted by the bunches when traversing a 1 micron thin titanium foil is coherent for wavelengths longer that the bunch length and extends into the millimeter wavelength range. A CTR far-infrared autocorrelator was used to measure the bunch length as a function of the accelerator. The results obtained with this autocorrelator are the only measurements of the SLAC ultra-short bunches to date. Experimental results, as well as the limitations of the measurements and the future improvements to the autocorrelator will be presented. |
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| RPAT095 | Time Resolved X-Ray Spot Size Diagnostic | diagnostics, target, electron, shielding | 4302 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. |
A diagnostic was developed for the determination of temporal history of an X-ray spot. A pair of thin (0.5 mm) slits image the x-ray spot to a fast scintillator which is coupled to a fast detector, thus sampling a slice of the X-Ray spot. Two other scintillator/detectors are used to determine the position of the spot and total forward dose. The slit signal is normalized to the dose and the resulting signal is analyzed to get the spot size. The position information is used to compensate for small changes due to spot motion and misalignment. The time resolution of the diagnostic is about 1 ns and measures spots from 0.5 mm to over 3 mm. The theory and equations used to calculate spot size and position are presented, as well as data. The calculations assume a symmetric, Gaussian spot. The spot data is generated by the ETA II accelerator, a 2kA, 5.5 MeV, 60ns electron beam focused on a Tantalum target. The spot generated is typically about 1 mm FWHM. Comparisons are made to an X-ray pinhole camera which images the XRay spot (in 2D) at four time slices. |
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| RPPE026 | Operating Experience with Meson Production Targets at TRIUMF | target, proton, radiation, beam-losses | 1919 | ||
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High power targets are now required for operation at beam powers in excess of 1 MW for spallation neutron sources and neutrino factories. TRIUMF has been operating beryllium and graphite meson production targets for many years. Although the proton beam power of 100 kW at 500 MeV is lower, the beam densities and fluences are higher than most operating solid targets as other accelerators use rotating targets or larger beam spots. The beam size on the TRIUMF targets is maintained at 0.15 cm2 and this beam density leads to proton fluences of 1·1023 protons/cm2 per year. The beryllium targets are rectangular rods immersed in a water-cooled stainless steel jacket. The pyrolytic graphite targets consist of pie-shaped segments bonded to a water-cooled copper saddle. Operating experience shows that the graphite targets suffer thermal damage above beam currents of 120 uA but will operate for long periods at 100 uA. The beryllium targets can operate to 200 uA and appear to survive radiation damage beyond 10 dpa although some targets have failed due to structural damage. This paper will describe the operating experience with these targets and present some thermal and radiation calculations.
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| RPPE042 | Aperture and Field Constraints for the Vacuum System in the LHC Injection Septa | vacuum, injection, septum, shielding | 2732 | ||
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Each beam arriving from the SPS has to pass through five injection septum magnets before being kicked onto the LHC orbit. The injection layout implies that the vacuum chambers for the two circulating beams pass through the septum magnet yokes at a flange distance from the chamber of the beam to be injected. Specially designed vacuum chambers and interconnections provide the required straightness and alignment precision, thus optimising the aperture for both the circulating and injected beams, without affecting the quality of the magnetic dipole field seen by the injected beam. The circulating beams are shielded against the magnetic stray field by using μ-metal chambers with a thickness of 0.9 mm to avoid saturation of the μ-metal (0.8 T), coated with copper (0.4 mm) for impedance reasons and NEG for pumping and electron cloud purposes. A sufficiently large gap between the iron yoke and the μ-metal chamber allows an in-situ bake-out at 200°C, based on a polyimide/stainless steel/polyimide sandwich structure with an overall thickness of 0.2 mm. The constraints will be described and the resulting vacuum system design, the apertures and the residual stray field will be presented.
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| RPPP024 | Comparison of Beam-Based Alignment Algorithms for the ILC | emittance, linac, quadrupole, shielding | 1847 | ||
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Funding: NSF and DOE. |
The International Linear Collider (ILC) alignment tolerances require more sophisticated alignment techniques than those provided by survey alone. Various Beam-Based Alignment algorithms have been proposed to achieve the desired low emittance preservation. These algorithms are compared and their merits identified using the TAO accelerator simulation program. |
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| RPPT059 | Spectrum from the Proposed BNL Very Long Baseline Neutrino Facility | target, proton, simulation, background | 3476 | ||
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Funding: The work was performed with the support of the U.S. DOE under Contract No. DE-AC02-98CH10886. |
This paper calculates the neutrino flux that would be seen at the far detector location from the proposed BNL Very Long Baseline Neutrino Facility. The far detector is assumed to be located at an underground facility in South Dakota 2540 km from BNL. The neutrino beam facility uses a 1 MW upgraded AGS to provide an intense proton beam on the target and a magnetic horn to focus the secondary pion beam. The paper will examine the sensitivity of the neutrino flux at the far detector to the positioning of the horn and target so as to establish alignment tolerances for the neutrino system. |
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| RPPT070 | Status Report on the Installation of the Warm Sections for the Superconducting Linac at the SNS | vacuum, SNS, linac, quadrupole | 3828 | ||
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Funding: SNS is managed by UT-Battelle, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley and Oak Ridge. |
The SNS superconducting linac (SCL) consists of 23 cryomodules (CMs), with possibly 9 additional CMs being added for future energy upgrade from 1 GeV to 1.3 GeV. A total of 32 warm sections separate the comparatively short CMs, and this allows a CM exchange within 48 hours, in order to meet demanding beam availability specifications. The 32 warm section chambers are installed between each pair of CMs, with each section containing a quadrupole doublet, beam diagnostics, and pumping. The chambers are approximately 1.6 m long, have one bellow installed at each end for alignment, and are pumped by one ion-pump. The preparation and installation of these chambers must be made under stringent clean and particulate-free conditions, in order to ensure that the performance of the SCL CMs is not compromised. This paper will discuss the development of the cleaning, preparation, and installation procedures that have been adopted for the warm sections, and the vacuum performance of this system. |
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| FPAE021 | Alignment and Steering for Injection and Multi-Turn Operation of the University of Maryland Electron Ring (UMER) | injection, quadrupole, dipole, electron | 1709 | ||
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Funding: This work is funded by US Dept. of Energy grant numbers DE-FG02-94ER40855 and DE-FG02-92ER54178. |
The injection line and main lattice for the University of Maryland Electron Ring (UMER) has been completed. The electron beam has been guided around the full 360 degrees of the ring. Beam steering and matching in the injection line is achieved with six quadrupole magnets and several small steering dipole magnets. The dipole component of an offset quadrupole and a pulsed dipole are used to achieve the 10 degree bend required from the injection line into the ring. The pulsed dipole is designed to operate with a short pulse (2 kV, -30 A, 100 ns flat top duration) for injection superimposed on a long pulse (300 V, 15 A, 20·10-6 s duration) for multiple beam passes. The beam is controlled in the recirculating ring with a regular lattice of 36 dipole and 72 quadrupole magnets. Initial experimental results of the beam transport and control will be presented. |
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| FPAE046 | Initial Test of the PEFP 20MeV DTL | vacuum, proton, klystron, power-supply | 2917 | ||
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Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government. |
A conventional 20MeV drift tube linac (DTL) for the Proton Engineering Frontier Project (PEFP) has been developed as a low energy section of 100MeV accelerator. The machine consists of four tanks with 152 cells supplied with 900kW RF power from 350MHz klystron through the ridge-loaded waveguide coupler. We assembled the fabricated accelerator components and aligned each part with care. We have also prepared the subsystems for the test of the DTL such as RF power delivery system, high voltage DC power supply, vacuum system, cooling system, measurements and control system and so on. The detailed description of the initial test setup and preliminary test results will be given in this paper. |
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| FPAT041 | Design and Simulation of an Anode Stalk Support Insulator | simulation, vacuum, radiation, power-supply | 2663 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. |
An anode stalk support insulator in a magnetically insulated transmission line was designed and modeled. One of the important design criteria is that within space constraints, the electric field along the insulator surface has to be minimized in order to prevent a surface flashover. In order to further reduce the field on the insulator surface, metal rings between insulator layers were also specially shaped. To facilitate the design process, electric field simulations were performed to determine the maximum field stress on the insulator surfaces and the transmission line chamber. |
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| FPAT077 | An Accelerator Control Middle Layer Using Matlab | simulation, lattice, photon, feedback | 4009 | ||
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Funding: U.S. Department of Energy under Contract No. DEAC03-76SF00098. |
Matlab is a matrix manipulation language originally developed to be a convenient language for using the LINPACK and EISPACK libraries. What makes Matlab so appealing for accelerator physics is the combination of a matrix oriented programming language, an active workspace for system variables, powerful graphics capability, built-in math libraries, and platform independence. A number of software toolboxes for accelerators have been written in Matlab – the Accelerator Toolbox (AT) for machine simulations, LOCO for accelerator calibration, Matlab Channel Access Toolbox (MCA) for EPICS connections, and the Middle Layer. This paper will describe the MiddleLayer software toolbox that resides between the high-level control applications and the low-level accelerator control system. This software was a collaborative effort between ALS and Spear but was written to easily port. Five accelerators presently use this software – Spear, ALS, CLS, and the X-ray and VUV rings at Brookhaven. The Middle Layer functionality includes energy ramp, configuration control, global orbit correction, local beam steering, insertion device compensation, beam-based alignment, tune correction, response matrices, and script-based physics studies. |
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| FPAT083 | H5Part: A Portable High Performance Parallel Data Interface for Particle Simulations | simulation | 4129 | ||
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Largest parallel particle simulations, in six dimensional phase space generate wast amont of data. It is also desirable to share data and data analysis tools such as ParViT (Particle Visualization Toolkit) among other groups who are working on particle-based accelerator simulations. We define a very simple file schema built on top of HDF5 (Hierarchical Data Format version 5) as well as an API that simplifies the reading/writing of the data to the HDF5 file format. HDF5 offers a self-describing machine-independent binary file format that supports scalable parallel I/O performance for MPI codes on a variety of supercomputing systems and works equally well on laptop computers. The API is available for C, C++, and Fortran codes. The file format will enable disparate research groups with very different simulation implementations to share data transparently and share data analysis tools. For instance, the common file format will enable groups that depend on completely different simulation implementations to share custom data analysis tools like ParViT without modification. We will show examples and benchmak data for various platforms.
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