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Particle Accelerator Conference, 2007. PAC. IEEE

Date 25-29 June 2007

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Displaying Results 1 - 25 of 1431
  • Industrial exhibitors

    Publication Year: 2007 , Page(s): i
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (51 KB)  

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  • Towards 100% polarization in the optically-pumped polarized ion source

    Publication Year: 2007 , Page(s): 3771 - 3773
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (501 KB) |  | HTML iconHTML  

    The depolarization factors in the multi-step spin-transfer polarization technique and basic limitations on maximum polarization in the OPPIS (Optically-Pumped Polarized H* Ion Source) are discussed. Detailed studies of polarization losses in the RHIC OPPIS and the source parameters optimization resulted in the OPPIS polarization increase to 86-90%. This contributed to increasing polarization in the AGS and RHIC to 65 ~ 70%. View full abstract»

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  • Advanced RF-driven H- ion sources at the SNS

    Publication Year: 2007 , Page(s): 3774 - 3776
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB) |  | HTML iconHTML  

    The US spallation neutron source* (SNS), will require substantially higher average and pulse H" beam current than can be produced from conventional H- ion sources such as the baseline LBNL-SNS source. H- currents of 70-100 mA with an RMS emittance of 0.20-0.35 π mm mrad and a ˜7% duty-factor will be needed for the SNS power upgrade project in 2010. We are therefore investigating several advanced ion source concepts based on RF plasma excitation. First, a generalized discussion of our source development strategy is presented as well as the performance characteristics of a large-plasma-volume, external antenna source based on an AI2O3 plasma chamber. The design and results of computational modeling of a high-power version of this source featuring an AlN plasma chamber is subsequently discussed as well as a high-efficiency extraction system necessary for high- current operation. View full abstract»

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  • The spallation neutron source accumulator ring RF system

    Publication Year: 2007 , Page(s): 3795 - 3797
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1069 KB) |  | HTML iconHTML  

    The spallation neutron source (SNS) accumulator ring is a fixed-frequency proton storage ring located at the output of the SNS linear accelerator (Linac). Its purpose is to redistribute the 1 millisecond long H-beam pulses from the SNS Linac into high-intensity 695 nanosecond long pulses of protons for delivery to the neutron target. The RF bunching system controls longitudinal beam distribution during the accumulation process and maintains a 250+ nanosecond gap required for beam extraction. The RF system consists of three stations which operate at the beam revolution frequency of 1.05 MHz and a fourth station providing a second harmonic component at 2.1 MHz. The beam pulse at extraction consists of 1.6e14 protons representing a peak beam current of 52 amperes. The system utilizes four 600 kW tetrodes to provide the RF current necessary to produce the 40 kV peak fundamental frequency bunching voltage and to control phase and amplitude at high beam current. A 20 kV peak second harmonic voltage is intended to control longitudinal beam distribution to control the peak circulating current. In this paper we review the design concepts incorporated into this heavily beam-loaded RF system and discuss its commissioning status. View full abstract»

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  • RF amplifier choice for the ISAC superconducting linac

    Publication Year: 2007 , Page(s): 3798 - 3800
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    A superconducting linac is being commissioned at TRIUMF as an extension to the existing room temperature accelerator of exotic ions at ISAC. It will increase the isotope final energy from 1.5 to 6.5 MeV/u. Acceleration is accomplished in 40 bulk niobium quarter wave superconducting cavities operating at 106 and 141 MHz. Each cavity is energized from an independent RF amplifier with power rating up to 1 kW cw. Both vacuum tube and solid-state amplifiers were considered as a viable option for the drivers. The paper compares many important parameters of these 2 amplifiers such as reliability, serviceability, capital and maintenance costs, as well as operating characteristics: gain linearity, phase noise, phase drift and others. Test results of prototypes of both types of amplifiers and 1-year operational experience of 20 tube amplifiers are discussed. Based on that the amplifier design recommendations are formulated. View full abstract»

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  • The commissioning of the LHC technical systems

    Publication Year: 2007 , Page(s): 3801 - 3803
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    The LHC is an accelerator with unprecedented complexity where the energy stored in magnets and the beams exceeds other accelerators by one-to-two orders of magnitude. To ensure a safe and efficient machine start-up without being plagued by technical problems, a phase of "hardware commissioning" was introduced: a thorough commissioning of technical systems without beam. This activity started in June 2005 with the commissioning of individual systems, followed by operating a full sector, one eighth of the machine; the commissioning is expected to last until spring 2008 when commissioning with beam will start. The LHC architecture allows the commissioning of each of the eight sectors independently from the others, before the installation of other sectors is complete. An important effort went into the definition of the programme and the organization of the coordination in the field, as well as in the preparation of the tools to record and analyze test results. This paper discusses the experience with this approach, presents results from the commissioning of the first LHC sector and gives an outlook for future activities. View full abstract»

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  • Sub-10 femtosecond stabilization of a fiber-link using a balanced optical cross-correlator

    Publication Year: 2007 , Page(s): 3804 - 3806
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (406 KB) |  | HTML iconHTML  

    A drift free synchronization distribution system with femtosecond accuracy is of great interest for free-electron-lasers such as FLASH or the European XFEL. Stability at that level can be reached by distributing laser pulses from a mode-locked erbium-doped fiber laser over length-stabilized fiber-links. In this paper, we present a prototype of a fiber-link stabilization system based on balanced optical cross-correlation. The optical cross-correlation offers drift-free timing jitter detection. With this approach we were able to reduce the timing jitter added by a 400 m long fiber-link installed in a noisy accelerator environment to below 10 fs (rms). View full abstract»

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  • Systems design concepts for optical synchronization in accelerators

    Publication Year: 2007 , Page(s): 3807 - 3809
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (269 KB) |  | HTML iconHTML  

    Development of accelerator-based light sources is expanding the size of femtosecond laser systems from tabletop devices up to kilometer-scale facilities. New optical techniques are needed to maintain temporal stability in these large systems. We present methods for distributing timing information over optical fiber using continuous optical waves, and how these can be employed in advanced accelerators requiring less than 100 fs timing stability. Different techniques combine to form a tool set that can provide for synchronization down to a few femtoseconds. Practical examples are given for timing systems applicable to FELs now under construction, with experimental results to show these systems can be built with required performance. View full abstract»

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  • Survey of LLRF development for the ILC

    Publication Year: 2007 , Page(s): 3810 - 3812
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    The key to a successful LLRF design for the International Linear Collider (ILC) relies on a combined effort from the different laboratories involved in this global project. This paper covers the ILC LLRF design progress both long term and for current test facilities around the world. The SIMCON controller board, originally developed at DESY has been successfully used at FNAL to control superconducting capture cavity I and II. LLRF team leaders from DESY, KEK and FNAL have worked together toward a common design and costing estimate for the ILC LLRF. This paper gives a general overview of the LLRF development achieved through continuous collaboration and communication between the various labs involved in the ILC LLRF design process. View full abstract»

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  • Magnet acceptance and allocation at the LHC magnet evaluation board

    Publication Year: 2007 , Page(s): 3739 - 3741
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (221 KB) |  | HTML iconHTML  

    The normal and superconducting magnets for the LHC ring have been carefully examined to insure that each of about 1900 assemblies is suitable for the operation in the accelerator. Hardware experts and accelerator physicists have contributed to this work that consisted in magnet acceptance, and sorting according to geometry, field quality and quench level. This paper gives a description of the magnet approval mechanism that has been running since four years, reporting in a concise summary the main results achieved. View full abstract»

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  • LHC magnet tests: Operational techniques and empowerment for successful completion

    Publication Year: 2007 , Page(s): 3742 - 3744
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB) |  | HTML iconHTML  

    The LHC magnet tests operation team developed various innovative techniques, particularly since early 2004, to complete the superconductor magnet tests by Feb. 2007. Overall and cryogenic priority handling, rapid on-bench thermal cycling, rule-based goodness evaluation on round-the-clock basis, multiple, mashed web systems are some of these techniques applied with rigour for successful tests completion in time. This paper highlights these operation empowerment tools which had a pivotal role for success. A priority handling method was put in place to enable maximum throughput from twelve test benches, having many different constraints. For the cryogenics infrastructure, it implied judicious allocation of limited resources to the benches. Rapid on-bench thermal cycle was a key strategy to accelerate magnets tests throughput, saving time and simplifying logistics. First level magnet appraisal was developed for 24 hr decision making so as to prepare a magnet further for LHC or keep it on standby. Web based systems (tests management and E-traveller) were other essential ideas to track & coordinate various stages of tests handled by different teams. View full abstract»

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  • Simulation-driven optimization of heavy-ION production in ECR sources

    Publication Year: 2007 , Page(s): 3786 - 3788
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    Next-generation heavy-ion beam accelerators require a wide variety of high charge state ion beams (from protons to uranium) with up to an order of magnitude higher intensity than that demonstrated with conventional electron cyclotron resonance (ECR) ion sources. Optimization of the ion beam production for each element is therefore required. Efficient loading of the material into the ECR plasma is one of the key elements for optimizing the ion beam production. High-fidelity simulations provide a means to understanding the deposition of uncaptured metal atoms along the walls. This information would help to optimize the loading process into the ECR plasma. We are currently extending the plasma simulation framework VORPAL with models to investigate effective loading of heavy metals into ECR ion source via alternate mechanisms, including vapor loading, ion sputtering and laser ablation. First results of the ion production for different loading scenarios are presented. View full abstract»

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  • Inhomogeneities in beams extracted from ECR ION sources

    Publication Year: 2007 , Page(s): 3789 - 3791
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB) |  | HTML iconHTML  

    An examination of heavy ion beam profiles using viewing targets and CCD cameras at both the NSCL and GSI shows highly structured patterns. These structures generally have a 3-fold symmetry reflecting the highly- magnetized nature of the ion formation within the plasma chamber. A program of experiment and modeling with KOBRA3-INP [1], TRANSPORT [2], GICOSY [3] is continuing. Results of this program to date are discussed. View full abstract»

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  • 30 GHz high-gradient accelerating structure test results

    Publication Year: 2007 , Page(s): 3818 - 3820
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1087 KB) |  | HTML iconHTML  

    The CLIC study is high power testing accelerating structures in a number of different materials and accelerating structure designs to understand the physics of breakdown, determine the appropriate scaling of performance and in particular to find ways to increase achievable accelerating gradient. The most recent 30 GHz structures which have been tested include damped structures in copper, molybdenum, titanium and aluminum. The results from these new structures are presented in this paper. View full abstract»

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  • RF structures for Linac4

    Publication Year: 2007 , Page(s): 3821 - 3823
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (326 KB) |  | HTML iconHTML  

    Linac4 is proposed to replace the existing proton linac at CERN (Linac2). Using an increased injection energy of 160 MeV instead of 50 MeV, Linac4 is expected to double the beam intensity in the PS Booster (PSB) and will thus be the first step towards higher brightness beams in the LHC. In this paper we re-assess the choice of RF structures for Linac4. Different accelerating structures for different energy ranges are compared in terms of RF efficiency, ease of construction and alignment, and necessary infrastructure. Eventually we present the final choice for Linac4. View full abstract»

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  • Efficient accelerating structures for low-energy light IONS

    Publication Year: 2007 , Page(s): 3824 - 3826
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (283 KB) |  | HTML iconHTML  

    The radio-frequency quadrupole (RFQ) accelerator is the best structure immediately after an ion source for accelerating light-ion beams with considerable currents. On the other hand, the higher-energy part of the RFQ is known to be not a very efficient accelerator. We consider alternative room-temperature RF accelerating structures for the beam velocities in the range of a few percent of the speed of light - including H-mode cavities and drift-tube linacs - and compare them with respect to their efficiency, compactness, ease of fabrication, and overall cost. Options for the beam transverse focusing in such structures are discussed. Possible applications include a compact deuteron-beam accelerator up to the energy of a few MeV for homeland defense. View full abstract»

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  • Thermomechanical design of normal-conducting deflecting cavities at the advanced photon source for short x-ray pulse generation

    Publication Year: 2007 , Page(s): 3827 - 3829
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    A normal-conducting deflecting cavity is being designed at the Advanced Photon Source (APS) as a part of the short x-ray pulse project intended to provide users with approximately 2 picosecond x-rays. The system will use two pairs of 3-cell cavities in sectors 6ID and 7ID for the generation of the x-ray pulse in the 7ID beamline. The 3-cell cavities are designed to provide the desired beam deflection while absorbing in excess of 4 kW of power from a pulsed rf system and up to 2.6 kW in the damper system of high-order mode (HOM) and low-order mode (LOM) waveguides. Since the cavity frequency is very sensitive to thermal expansion, the cooling water system is designed so that it is able to control cavity temperature to within 0.1degC. This paper describes the optimization of the thermomechanical design of the cavity based on calculation of thermal stresses and displacement caused by the generated heat loads, and presents the design of a cooling water system required for the proper operation of the cavities. View full abstract»

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  • Preliminary studies for top-up operations at the Australian Synchrotron

    Publication Year: 2007 , Page(s): 3856 - 3858
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (269 KB) |  | HTML iconHTML  

    The Australian Synchrotron is now a fully commissioned synchrotron light source providing beam for users [1]. With the facility now fully operational, the next major advancement in machine operations will be top-up mode. The advantages of running in a dynamic top-up mode are well documented by other third generation light sources (see for examples references [2, 3, 4]) ; in broad terms it leads to a better quality beam for some users, and better experimental results. An overview will be given of the top-up runs that have been conducted and the instrumentation that was used. It has been demonstrated that top-up operation is possible, however improvements in injection efficiency and beam stability during injection are required before this can become a routine mode of operation. View full abstract»

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  • Measurements of impedance and beam instabilities at the Australian Synchrotron

    Publication Year: 2007 , Page(s): 3859 - 3861
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (239 KB) |  | HTML iconHTML  

    In this paper we present the first measurements of machine impedance and observed beam instabilities at the Australian Synchrotron. Impedance measurements are made by studying the single bunch behaviour with beam current, using optical and X-ray diagnostic beamlines. An observed coupled-bunch instability, its cause and cure is also discussed. View full abstract»

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  • Storage ring turn-by-turn BPMS at the Australian Synchrotron

    Publication Year: 2007 , Page(s): 3865 - 3867
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (386 KB) |  | HTML iconHTML  

    The Australian synchrotron's Storage Ring is equipped with a full compliment of 98 Libera electron beam position processors from I-tech (EBPPs) [1]. The EBPPs are capable of measuring beam position data at turn-by-turn (TBT) rates and have long history buffers. TBT data from the EBPPs has been used to determine the linear optics of the storage ring lattice using techniques developed at other facilities. This is a useful complement to other methods of determining the linear optics such as LOCO. Characteristics of the EBPPs such as beam current dependence have been studied during commissioning and will also be presented. View full abstract»

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  • Design of button beam position monitor for the Brazilian Synchrotron light source

    Publication Year: 2007 , Page(s): 3871 - 3873
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (439 KB) |  | HTML iconHTML  

    We present the electrical and mechanical design of a button beam position monitor (BPM) recently developed and installed in the UVX electron storage ring at the Brazilian Synchrotron Light Laboratory (LNLS). The first characterization results will also be presented. This development started when we observed strong correlation between false stripline BPM readings and the external temperature of this BPM. Simulations indicate that the temperature gradient in the BPM body can cause deformations that could explain the false readings in some BPMs. The small dimension of the button compared to the stripline and the better thermal isolation between the button and the BPM body should contribute to minimize this problem. View full abstract»

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  • Image charge effects in dynamics of intense off-axis beams

    Publication Year: 2007 , Page(s): 3880 - 3882
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB) |  | HTML iconHTML  

    This paper analyzes the combined envelope-centroid dynamics of magnetically focused high intensity charged beams surrounded by conducting walls. Similarly to the case were conducting walls are absent, we show that the envelope and centroid dynamics decouples from each other. Mismatched envelopes still decay into equilibrium with simultaneous emittance growth, but the centroid keeps oscillating with no appreciable energy loss. Some estimates are performed to analytically obtain some characteristics of halo formation seen in the full simulations. View full abstract»

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  • Wave breaking and particle jets in inhomogeneous beams

    Publication Year: 2007 , Page(s): 3886 - 3888
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB) |  | HTML iconHTML  

    We analyze the dynamics of inhomogeneous, magnetically focused high-intensity beams of charged particles. While for homogeneous beams the whole system oscillates with a single frequency, any inhomogeneity leads to propagating transverse density waves which eventually result in a singular density build up, causing wave breaking and jet formation. The theory presented in this paper allows to analytically calculate the time at which the wave breaking takes place. It also gives a good estimate of the time necessary for the beam to relax into the final stationary state consisting of a cold core surrounded by a halo of highly energetic particles. View full abstract»

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  • Transition from isotropic to anisotropic beam profiles in a uniform linear focusing channel

    Publication Year: 2007 , Page(s): 3892 - 3894
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB) |  | HTML iconHTML  

    This paper examines the transition from isotropic to anisotropic beam profiles in a uniform linear focusing channel. Considering a high-intensity ion beam in space- charge dominated regime and large beam size-rms mismatched initially, observe a fast anisotropy situation of the beam characterized for a transition of the transversal section round to elliptical with a coupling of transversal emittance driven for collective instabilities of nonlinear space-charge forces. View full abstract»

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  • Emittance measurements at the 100 keV beam stage of the injector linac of the IFUSP microtron

    Publication Year: 2007 , Page(s): 3898 - 3900
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (940 KB) |  | HTML iconHTML  

    The injector linac consists of a 100-keV electron gun, a beam conforming stage, and two acceleration structures. The beam focalization is made by solenoids, and correcting coils are provided for steering. In this work we describe the beam emittance measurement on the beam conforming stage. Some results are shown. The injector linac consists of a beam conforming stage, with chopper and buncher systems, and two acceleration structures [2] (the first one with variable beta, and the second one divided into two parts with different beta). There is a 3-mm diameter collimator at the entrance to the first acceleration structure. View full abstract»

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