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MOPKF012 | A 7T Multipole Wiggler in BESSY II: Implementation and Commissioning Results | gun, wiggler, damping, alignment | 324 | ||||||
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To generate hard X-ray beams for residual stress analysis and for magnetic scattering with the BESSY II SR source, a 7T wiggler with 17 poles has been implemented. Several problems had to be solved. Wake fields induced by smaller steps in the geometry of the radiation shield inside the beam chamber led to intolerable LHe consumption, which have been analysed numerically and then cured by improving the shield geometry. Much of the routine operation procedures are influenced by the unusually high radiation power level of max. 55 kW. For system protection an interlock system dumps the electron beam automatically in case of relevant error events. This wiggler is by far the strongest perturbation of the linear beam optics, breaking seriously the symmetry of the ring. Beam optical parameters including tune shift and beta beat have been measured to quantify these perturbations and develop efficient cures to limit the negative effects on beam lifetime and dynamic aperture. So far the wiggler is operated at 2.8 T and max. currents up to 250 mA in normal user shifts.
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MOPKF013 | The Influence of the Main Coupler Field on the Transverse Emittance of a Superconducting RF Gun | wiggler, damping, gun, alignment | 327 | ||||||
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For the Rossendorf superconducting RF gun project the influence of the additional RF field, created in the cavity by the RF power flow at the main coupler, is discussed. One end of the gun cavity is occupied by the cathode insert, so all flanges are concentrated on the other end. In the "flange plane" of the cavity two HOM coupler, the pic up and the main coupler are located. If we normalize the RF field in the cavity by the condition Eacc = 25MV/m and assume a beam power of 10kW (CW mode), we obtain an quality factor Qext = 2.2*10**7. A three dimensional field calculation using the MAFIA code, gives the field perturbation near the main coupler. Tracking calculation with ASTRA show,that this perturbation increases the transversel emittance between 1 and 4%, nearly independent from the bunch charge. This result shows, that for average beam powers in the vicinity of 10kW effects, connected with the assymetric input of RF power can be neglected.
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MOPKF014 | Emittance Compensation of a Superconducting RF Photoelectron Gun by a Magnetic RF Field | wiggler, damping, gun, alignment | 330 | ||||||
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For compensation of transverse emittance in normal conducting RF photoelectron guns a static magnetic field is applied. In superconducting RF guns the application of a static magnetic field is impossible. Therefore we put instead of a static field a magnetic RF field (TE - mode) together with the corresponding accelerating mode into the superconducting cavity of the RF gun. For a 3 _ cell cavity of the superconducting gun with frequencies f = 1.3GHz for the accelerating mode and f = 3.9 GHz for the magnetic mode and a bunch charge of 1 nC a transversal emittance of 0.5 mm mrad has been obtained. In this case the maximal field strength on the axis were Ez = 50 MV/m for the accelerating mode and Bz = 0.34 T for the magnetic mode.(This corresponds to Bs(max) = 0.22T on the surface of the cavity). Possibilities for the technical realization (input of RF power for the TE mode, tuning of two frequencies in one cavity, phase stability) are discussed.
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MOPKF015 | A Superconducting Photo-Injector with 3+1/2- Cell Cavity for the ELBE Linac | wiggler, damping, gun, alignment | 333 | ||||||
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After successful tests of an SRF gun with a superconducting half-cell cavity [*], a new SRF photo-injector for CW operation at the ELBE linac has been designed. In this report the design layout of the SRF photo-injector, the parameters of the superconducting cavity and the expected electron beam parameters are presented. The SRF gun has a 31/2-cell niobium cavity working at 1.3 MHz and will be operated at 2 K. The three full cells have TESLA-like shapes. In the half-cell the photocathode is situated which will be cooled by liquid nitrogen.
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* D. Janssen et. al., First operation of a superconducting RF-gun, Nucl. Instr. and Meth. A507(2003)314 |
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MOPKF016 | S2E Simulations on Jitter for European XFEL Project | wiggler, damping, gun, alignment | 336 | ||||||
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In order to generate stable 0.1 nm wavelength SASE source at the European X-ray laser project XFEL, we should supply high quality electron beams with constant beam characteristics to a 200 m long undulator. Generally, beam parameters such as peak current and energy spread are significantly dependent on jitter or error in RF phase and RF amplitude of superconducting accelerating modules, and magnetic field error of bunch compressors. In this paper, we describe the start-to-end simulations from the cathode to the end of linac to determine the jitter and error tolerances for the European XFEL project.
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MOPKF031 | SOLEIL Insertion Devices: The Progress Report | wiggler, insertion, vacuum, damping | 369 | ||||||
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The French national synchrotron radiation source SOLEIL is planned to start operation in 2006 with several different insertion devices installed in the storage ring either from "day one" or within the first year. The list of high-priority insertion devices includes: 3 planar hybrid in-vacuum undulators with the period of 20 mm; 3 Apple-II type PPM undulators with the period of 80 mm; 3 electromagnet elliptical undulators with the period of 256 mm, and a 640 mm period elliptical electromagnet undulator offering advanced possibilities for fine-tuning of polarization states of the emitted radiation. The emission of all these undulators is covering wide spectral range extending from hard X-rays to UV. Pre-design of the IDs was done by SOLEIL. The construction will be done by industrial companies and institutions with production capabilities. Magnetic assembly of the Apple-II and in-vacuum undulators is planned to be done in collaboration with ELETTRA and ESRF. The final magnetic measurements of all the IDs will be made in the SOLEIL magnetic measurements laboratory. The paper will present peculiarities of the magnetic design, calculated maximum-flux spectra and associated heat load in various modes of operation.
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MOPKF032 | Status of the ESRF Insertion Devices | undulator, wiggler, damping, alignment | 372 | ||||||
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The ESRF insertion devices are the object of a continuous refurbishment in order to follow the changing needs of the beamlines and increase their performances. The successful development of the narrow aperture aluminum chambers pumped by non evaporable getter has resulted in the reduction of the minimum gap from 16 mm to 11 mm . A new set of undulator magnetic assemblies with shorter magnetic periods are being prepared that make use of the lower gap. .A prototype of a new type of revolver undulator support has been completed and successfully tested. Such a structure allows the beamline user to switch between two different undulator periods in less than a minute. Three additional devices will be constructed in 2004. Three new in-vacuum undulators have been installed on the ring. One of them is based on an hybrid magnetic structure and achieves a peak field 20% higher than a pure permanent magnet undulator of identical period. Their main magnetic measurements results and interactions with the stored beam are presented.
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MOPKF033 | Operational Improvements in the ESRF Injection Complex | injection, undulator, booster, wiggler | 375 | ||||||
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The ESRF injection complex, comprising a 200MeV linac, a booster accelerator with a top energy of 6GeV and two transfer lines, has been routinely injecting beam to the storage ring since the beginning of its operation. The newly implemented injection with front-end open'' triggered several operational improvements in order to maximise the reliability of the complex. A series of diagnostics (sychnotron light monitors, striplines, fast current transformers) were implemented allowing the measurement and monitoring of several components of the injected beam. New optics models were constructed and several application systems as the closed orbit correction or tune measurements have been upgraded. The operational procedures of injection at 100MeV in the booster and the injection efficiency maximisation were renewed and improved. Further developments for the uninterrupted operation of the storage ring during injection, such as the bunch cleaning in the booster were successfully tested.
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MOPKF034 | Status of the Development of Superconducting Undulators at the ESRF | injection, undulator, booster, wiggler | 378 | ||||||
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This note describes the present status of the development of superconducting undulators at the ESRF. Magnetic models of superconducting undulators suitable for the ESRF storage ring have been developed and evaluated. The superconducting undulators studied are horizontally polarizing undulators with a flat field profile and the vertical physical aperture of the undulator is 6 mm. Both 2D models of the local field in a period of the undulator and 3D models of the complete superconducting undulator, including the end sections and current leads, have been evaluated. The practical limit for the obtainable magnetic field has been estimated from the known performance of superconducting wire available from the cabling industry. This note also describes the conceptual design of the cryostat of the superconducting undulator and estimations of the expected heat load to the cryostat at different filling modes of the storage ring.
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MOPKF054 | Generation of Femtosecond Electron Pulses | injection, wiggler, booster, cathode | 431 | ||||||
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Femtosecond electron pulses have become an interesting tool for basic and applied applications, especially in time-resolved experiments and dynamic studies of biomolecules. Intense, coherent radiation can be generated in a broad far-infrared spectrum with intensities, which are many orders of magnitude higher than conventional sources including synchrotron radiation sources. At the Fast Neutron Research Facility (FNRF), Chiangmai University (Thailand), the SURIYA project has been established with the aim to produce femtosecond pulses utilizing a combination of a S-band thermionic rf-gun and an alpha-magnet as the magnetic bunch compressor. A specially designed rf-gun has been constructed to obtain the optimum beam characteristics for best bunch compression. Simulation results show that the bunch lengths as short as 50 fs rms can be expected at the experimental station. This rf- gun, an alpha-magnet and a 20 MeV linac with beam transport system were installed and are being commissioned to generate femtosecond electron bunches. To measure the bunch length of the electron pulses, a Michelson interferometer will be used to observe the spectrum of coherent FIR transition radiation via optical autocorrelation. The main results of numerical simulations and experimental results will be discussed in this paper.
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MOPKF077 | Reducing the Synchrotron Radiation on RF Cavity Surfaces in an Energy-recovery Linac | electron, wiggler, linac, cathode | 494 | ||||||
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In Energy Recovery Linac (ERL) light sources, a high energy, high current beam has to be bend into a superconducting linac to be decelerated. The synchrotron radiation produced in the last bending magnet before the linac shines into the superconducting structures if not collimated appropriately. Due to the length of the linac, the radiation cannot be completely guided through the superconducting structure, as in existing SRF storage rings. For the example of an ERL extension to the existing CESR storage ring at Cornell we estimate the magnitude of this problem by quantifying the heat load that can be accepted on a superconducting surface and by analyzing how much radiation is deposited on the cavity surfaces for different collimation schemes.
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MOPLT103 | Radiation Resistant Magnetic Sensors for Accelerators | wiggler, gun, electron, wakefield | 773 | ||||||
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The technology of obtaining the radiation resistant magnetic sensors, which characteristics remain stable under the irradiation with high dose of fast neutrons was designed. Radiation resistant sensors are developed on the base of InSb. While irradiation with neutron flux of 1010 n*cm-2*c-1 with energies 0.1
13 MeV, with the thermal neutrons part in the general flux of 20% and intermediate fluxes of 25%, the main sensors characteristics, that is their sensitivity to the magnetic field, change no more than for 0.05% up to the fluence of 1*1015 n*cm-2 and no more than for 1% up to the fluence of 3*1016 n*cm-2. Radiation resistant sensors are used for development of magnetic field monitoring system with measuring channels accuracy of 0,01%, which have a function of temperature measurement with the accuracy of 0.1 С at the place of sensor location, moreover, it has self diagnostics and self correction functions. This system passed the long-term testing of continuous 3 months operation at the Neutron Physics Laboratory, JINR, Dubna at the IBR-2 neutron reactor.
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MOPLT104 | Quantitative Optimisation Studies of the Muon Front-End for a Neutrino Factory | wiggler, gun, electron, wakefield | 776 | ||||||
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In a Neutrino Factory, short proton pulses hit a target, producing pions at widely varying angles and energies. Efficient pion capture is required to maximise the yield of decayed muons, which proceed via acceleration stages into a muon storage ring to produce neutrinos. This paper presents optimisation of a solenoidal decay channel designed for high-emittance pions, based on schemes from CERN and RAL. A non-linear tracking code has been written to run under an optimisation algorithm where every beamline element can be varied, which is then deployed as a distributed computing project. Some subsequent stages of muon beamline are also simulated, including RF and non-RF phase-rotation techniques and in one option, initial muon acceleration to 400MeV. The objective is to find optimal transmissions for each front-end concept.
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MOPLT105 | Implementation of MICE at RAL | wiggler, gun, electron, wakefield | 779 | ||||||
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The Muon Ionisation Cooling Experiment (MICE) is motivated by the vision of the neutrino factory (NF). The cost and practicality of the NF depends on an early control of the emittance of the muon beam that will be accelerated and stored to produce the neutrino beams. A number of possibilities for transverse cooling of the emittance have been proposed including ionisation cooling. In such a concept, the muon beam is alternatively slowed down in cryogenic absorbers (energy loss by ionisation) and then re-accelerated in RF cavities to replace the lost energy. This process reduces the transverse momentum of the beam while maintaining the average momentum in the z-direction. The energy absorbing material should be characterised by a high stopping power and low multiple scattering: The material of choice is liquid hydrogen. MICE will replicate a piece of the NF cooling channel. The engineering of a safe system with thin windows for the containment of the liquid hydrogen and other features needed to safely operate will test the practical application of the cooling scheme and its performance. MICE is proof of principle for this untried technology. The paper reviews progress in MICE and the plans for its implementation at RAL.
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The MICE Collaboration |
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MOPLT106 | MICE: the Muon Ionisation Cooling Experiment | wiggler, gun, electron, wakefield | 782 | ||||||
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The provision of intense stored muon beams would allow the properties of neutrinos to be measured precisely and provide a route to multi-TeV lepton-anti-lepton collisions. The short muon-lifetime makes it impossible to employ traditional cooling techniques while maintaining the muon-beam intensity. Ionisation cooling, a process in which the muon beam is passed through a series of liquid hydrogen absorbers followed by accelerating RF-cavities, is the proposed cooling technique. The international Muon Ionisation Cooling Experiment (MICE) collaboration proposes to perform an engineering demonstration of ionisation cooling. The MICE cooling channel, the instrumentation and the implementation at the Rutherford Appleton Laboratory is described together with the predicted performance of the channel and the measurements that will be made.
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MOPLT107 | Nanosecond-timescale Intra-bunch-train Feedback for the Linear Collider: Results of the FONT2 Run | feedback, wiggler, gun, electron | 785 | ||||||
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We report on experimental results from the December 2003/January 2004 data run of the Feedback On Nanosecond Timescales (FONT) experiment at the Next Linear Collider Test Accelerator at SLAC. We built a second-generation prototype intra-train beam-based feedback system incorporating beam position monitors, fast analogue signal processors, a feedback circuit, fast-risetime amplifiers and stripline kickers. We applied a novel real-time charge-normalisation scheme to account for beam current variations along the train. We used the system to correct the position of the 170 nanosecond-long bunchtrain at NLCTA, in both 'feed forward' and 'feedback' modes. We achieved a latency of 53 nanoseconds, representing a significant improvement on FONT1 (2002), and providing a demonstration of intra-train feedback for the Linear Collider.
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MOPLT108 | TESLA Linac-IP Simulations | wiggler, gun, luminosity, acceleration | 788 | ||||||
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We have formulated integrated simulations of the transport of the electron and positron bunches in the Linear Collider from the linac entrance through the beam delivery system and the interaction region, taking wakefield effects into account. We have set up the simulations to run on the 64-cpu prototpye Grid cluster at QMUL and generated results for various sets of input parameters for the TESLA and NLC machines. For TESLA we have evaluated the distortion of the phase-space of the bunches at the interaction point due to wakefields. We have calculated the luminosity degradation and the production of photons and e+e- pairs. We have simulated the performance of the intra-train beam feedback systems based on bunch position, angle and luminosity measures, and have evauated the luminosity recovery potential of these systems for TESLA and NLC.
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MOPLT109 | Longitudinal Schottky Spectra of Bunched Beams | wiggler, gun, luminosity, acceleration | 791 | ||||||
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In this paper we derive an expression for longitudinal Schottky spectrum of a bunched beam in a stationary bucket. The expression is then used to calculate longitudinal emittance of the antiproton beam in the Fermilab Recycler ring. The Recycler beam is bunched longitudinally by a barrier-bucket rf waveform. Under certain bucket conditions, dependence of synchrotron frequency on particle energy becomes non-monotonic. It complicates the Schottky spectrum derivation and interpretation; we address these difficulties in our paper.
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MOPLT110 | Stochastic Cooling in Barrier Buckets at the Fermilab Recycler | wiggler, gun, luminosity, acceleration | 794 | ||||||
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The Fermilab Recycler is a fixed 8-GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel near the ceiling. The role of stochastic cooling in the Recycler is to pre-cool the transverse phase-space of injected antiprotons for efficient electron cooling. This requires a gated stochastic cooling system working on beam confined in a barrier bucket. The performance of this system is reviewed. In addition, a study of the cooling rates and asymmptotic emittances as a function of beam intensity is presented.
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MOPLT111 | On using NEA Cathodes in an RF Gun | wiggler, electron, luminosity, acceleration | 797 | ||||||
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RF guns have been proven to deliver high brightness beams and therefore appear attractive as electron source for a linear collider. Only so far no polarized beams have been produced. To create a polarized electron beam GaAs NEA cathodes are used. Operating rf guns with a NEA cathode poses concerns in three areas, oxidation by residual gas, ion bombardment, and electron bombardment. In this paper we report about an attempt to reduce the vacuum pressure inside the gun by cooling it to cryogenic temperatures. Furthermore the energy deposition by ions and electrons will be quantified.
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MOPLT112 | Optimizing Non-Scaling FFAG Lattices for Rapid Acceleration | acceleration, wiggler, luminosity, beamloading | 800 | ||||||
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A linear approach to fixed field acceleration was first proposed [*,**] and successfully developed to support the rapid and large-emittance acceleration of muons for a Neutrino Factory or Muon Collider. Lattices have evolved from a simple F0D0-cell base as first proposed to a slightly more complex layout that has been referred to as a triplet configuration. In this work a methodology is developed for optimizing nonscaling lattices which demonstrates that the appropriate description is minimum momentum compaction, alpha=(dL/L)/(dp/p). Further, the triplet configuration is not used conventionally as a focusing telescope, but rather its optics is shown to resemble that of a F0D0-cell. This methodology is then used to propose and compare lattices for muon acceleration. Specifically a 2.5-5, 5-10, and 10-20 GeV/c lattice is proposed for muon acceleration and also one for a small, 10-20 MeV/c electron prototype machine.
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* C. Johnstone, "FFAG Non-scaling Lattice Design", talk, Proc 4th Int Conf on the Physics Potential and Development of the m+ m- Colliders, San Francisco, CA Dec.10-12, 1997, pgs 696-698** F. Mills, "Linear Orbit Recirculators", ibid, pgs 693-696 |
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MOPLT114 | Modeling of Beam Loss in Tevatron and Backgrounds in the BTeV Detector | acceleration, wiggler, luminosity, beamloading | 803 | ||||||
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Detailed STRUCT simulations are performed of beam loss rates in the vicinity of the BTeV detector in the Tevatron C0 interaction region due to beam-gas nuclear elastic interactions, outscattering from the collimator jaws and an accidental abort kicker prefire. Corresponding showers induced in the machine components and background rates on the BTeV Detector are modeled with the MARS14 code. It is shown that a steel mask located in front of the last four dipoles upstream the C0 can reduce the accelerator-related background rates in the detector by an order of magnitude.
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MOPLT115 | Numerical Simulations and Analyses of Beam-Induced Damage to the Tevatron Collimators | acceleration, wiggler, luminosity, beamloading | 806 | ||||||
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Numerical simulations are performed to analyze the Tevatron collimator damage happened in December 2003 that was induced by a failure in the CDF Roman Pot detector positioning during the collider run. Possible scenarios of this failure resulted in an excessive halo generation and superconducting magnet quench are studied via realistic simulations using the STRUCT and MARS14 codes. It is shown that the interaction of a misbehaved proton beam with the collimators result in a rapid local heating and a possible damage. A detailed consideration is given to the ablation process for the collimator material taking place in high vacuum. It is shown that ablation of tungsten (primary collimator) and stainless steel (secondary collimator) jaws results in creation of a groove in the jaw surface as was observed after the December's accident.
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MOPLT117 | An Electron Front End for the Fermilab Multi-species 8 GeV SCRF Linac | acceleration, wiggler, electron, linac | 809 | ||||||
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Fermilab is considering 8 GeV superconducting linac whose primary mission is to serve as an intense H- injector for the main injector. This accelerator is also planned to be used for accelerating various other species (e.g. electrons and muons). In the present paper we investigate the possibility of such a linac to accelerate a high brightness electron beam to ~7 GeV. We propose a design for the electron front end, based on a photoinjector, and consider the electron beam dynamics along the linac. Start-to-end simulations of the full accelerator for electrons are presented. Finally the potential applications of the such an electron beam are discussed.
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MOPLT118 | Muon Test Area at Fermilab | acceleration, wiggler, electron, luminosity | 812 | ||||||
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A construction of a new experimental area designed to develop, test and verify muon ionization cooling using the 400- MeV Fermilab Linac proton beam was finished in fall of 2003. This area will be used initially for cryogenic tests of liquid-hydrogen absorbers for the MUCOOL R&D program and, later, for high-power beam tests of these absorbers and other prototype muon-cooling apparatus. The experimental scenarios being developed for muon facilities involve collection, capture, and cooling of large-emittance, high-intensity muon beams~1013 muons at a repetition rate of 15Hz, so that conclusive tests of the apparatus require full Linac beam, or 1.6 x 1013 p at 15 Hz. The area has 12MW 805MHz, 5MW 201MHz RF, 4K Helium, 500W refrigeration and 400MeV H-/proton beam.
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MOPLT119 | Fabrication of X-band Accelerating Structures at FERMILAB | acceleration, vacuum, wiggler, electron | 815 | ||||||
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The RF Technology Development group at Fermilab is working together with the NLC and GLC groups at SLAC and KEK on developing technology for room temperature X-band accelerating structures for a future linear collider. We built seven 60cm long, high phase advance, detuned structures (HDS or FXB series). These structures have 150 degrees phase advance per cell, and are intended for high gradient tests. The structures were brazed in a vacuum furnace with a partial pressure of argon, rather than in a hydrogen atmosphere. We have also begun to build 60cm long, damped and detuned structures (HDDS or FXC / FXD series). So far, we have built 3 FXC structures. Our goal is to build 4 FXC and 2 FXD structures for the 8-pack test at SLAC by the end of March 2004, as part of the GLC/NLC effort to demonstrate the readiness of room temperature RF technology for a linear collider. This poster describes the RF structure factory infrastructure (clean rooms, vacuum furnaces, vacuum equipment, RF equipment etc.), and the fabrication techniques utilized (the machining of copper cells / couplers, quality control, etching, vacuum brazing, cleanliness requirements etc.) for the production of FXB and FXC structures.
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MOPLT120 | Proposals for Improvements of the Correction of Sextupole Dynamic Effects in the Tevatron Dipole Magnets | acceleration, vacuum, wiggler, electron | 818 | ||||||
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It is well known that the sextupole (b2) components in the superconducting dipole magnets decay during the injection plateau and snap back rapidly at the start of the ramp to flat top current. These so-called dynamic effects were originally discovered in the Tevatron. They are compensated for by the chromaticity correctors distributed around the ring. Imperfect control of the chromaticity during the snapback can contribute to beam loss and emittance growth. A thorough investigation of the chromaticity correction in the Tevatron was launched in the context of Run II, including beam chromaticity measurements and extensive magnetic measurements on a series of spare Tevatron dipole magnets. The study has yielded new information about the effect of the powering history on the dynamic b2. A companion paper at this conference describes in detail the results of these magnetic measurements [reference to George Velev's paper]. Study findings have given directive to new proposals for improvement of the b2 snapback correction in the Tevatron, including a revised functional form for the snapback algorithm and the elimination of the beam-less pre-cycle. This paper reports the results of beam studies performed recently to test these improved procedures.
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MOPLT121 | Water Flow Vibration Effect on the NLC RF Structure-girder System | acceleration, vacuum, wiggler, electron | 821 | ||||||
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In order to meet the vibration budget for the Next Linear Collider main Linac components, the vibration sources in the NLC girder are being studied. The activity is focused on the vibration induced by the cooling water flow for the 60 cm long accelerating copper structures. Understanding the vibration in the structures will enable us to push forward the design of the interface between the structures and the quadrupoles. This paper reports on the ongoing work and presents results from experimental data as well as finite element simulations.
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MOPLT122 | Dynamical Aperture Study for the NLC Main Damping Rings | acceleration, vacuum, electron, luminosity | 824 | ||||||
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A sufficiently large acceptance is critical for the NLC Main Damping Rings (MDR) as the high power carried by the beams demands very high injection efficiency. Both chromatic sextupoles and wiggler insertions, needed for damping, are substantial sources of nonlinearities limiting the dynamical aperture. We report on our latest studies on single particle dynamics for the MDR current lattice with and without inclusion of lattice errors and with attention paid to working point optimization. The possibility to use octupole magnets for compensation is also explored.
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TUYBCH01 | Design Criteria and Technology Challenges for the Undulators of the Future | gun, undulator, focusing, laser | 59 | ||||||
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Nowadays, undulators are essential devices for synchrotron radiation (SR) facilities since they generate a quasi-monochromatic radiation with various features, high brightness , high energy and special polarization characteristics. Particularly, demands for high-energy radiation in the X-ray region have become much stronger in many research fields. Accordingly, a short-period undulator design has been developed, because they increase the number of periods in a unit undulator length and as a consequence, they generate brilliant synchrotron radiation. Also, short undulator periodicity enables emission of high-energy photons, and it opens the way for X-ray beamline operation in medium size synchrotron radiation facilities, such as SLS, NSLS, PLS, CLS, ALS, SOLEIL, DIAMOND, SPEAR-III and so on. From the same reason, a short-period undulator is very attractive for SASE-FEL or ERL facilities, since it lowers the electron beam energy necessary for X-ray operation. As a result this design makes a whole facility design compact and economic. In the talk, I will review the status of the development on short-period undulators of various types (in-vacuum, superconducting and cryogenic types) and describe the future direction.
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TUYBCH02 | Technological Challenges for High Brightness Photo-injectors | gun, undulator, focusing, laser | 64 | ||||||
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Many applications, from linear colliders to free-electron lasers, passing through light sources and many other electron sources, require high brightness electron beams, usually produced by photo-injectors. Because certain parameters of these applications differ by several orders of magnitude, various solutions were implemented for the design and construction of the three main parts of the photo-injectors: lasers, photocathodes and guns. This paper summarizes the different requirements, how they lead to technological challenges and how R&D programs try to overcome these challenges. Some examples of state-of-the-art parts are presented.
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TUYLH03 | Challenges facing the Generation of MW Proton Beams using Rapid Cycling Synchrotrons | gun, positron, focusing, plasma | 113 | ||||||
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The MW proton source using rapid cycling synchrotron (RCS) has many challenging aspects, such as (1) large aperture magnets and much higher RF voltages per turn due to a low energy injection and a large and rapid swing of the magnetic field, (2) field tracking between many magnet-families under slightly saturated conditions, (3) RF trapping with fundamental and higher harmonic cavities, (4) H- charge stripping foil, (5) large acceptance injection and extraction straights, (6) beam loss collection, and (7) beam instabilities. These are discussed in details mainly on the basis of the J-PARC 3GeV RCS, which is under construction in Japan. Issues (3) to (7) are common with another scheme of MW spallation neutron source, i.e. full-energy linac + accumulator ring. Comparisons with the SNS design in the US are then made. Reliability/availability of these machines is very important theme which finally determines the successful operations. From the experiences in the existing machines, we will discuss the factors necessary toward the better performance.
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TUPLT180 | Results of the NASA Space Radiation Laboratory Beam Studies Program at BNL | focusing, bunching, betatron, ion | 1547 | ||||||
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The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. The purpose of the NSRL beam studies program is to develop a clear understanding of the beams delivered to the facility, to fully characterize those beams, and to develop new capabilities in the interest of understanding the radiation environment in space. In this report we will describe the first results from this program.
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WEOBCH01 | Performance Requirements for Monitoring Pulsed, Mixed Radiation Fields around High-energy Acclerators | focusing, kicker, bunching, beamloading | 147 | ||||||
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Radiation protection survey around CERN's High Energy Accelerators represents a major technical and physical challenge due to the pulsed and complexity of the mixed radiation fields. The fields are composed of hadrons, leptons and photons ranging in energy from fractions of eV to several 10 GeV. In preparation of the implementation of a Radiation Monitoring System for the Environment and Safety (RAMSES) of the future Large Hadron Collider (LHC) and its injectors comprehensive studies were performed to evaluate the suitability of different existing monitors for this task. Different ionization chambers were exposed to short, high-intensity radiation pulses and their saturation levels for high dose rates determined. Limiting factors such as recombination effects and the capacity of the electronics to process a high number of charges within very short time were studied in detail. These results are being used to optimize the design of the read-out electronics. In additional studies, the response of two different types of ionization chambers to high-energy radiation was investigated by measurements in the mixed radiation fields of the CERN EU high-energy Reference Field (CERF) facility. The results of the experiments agreed well with calculations, clearly demonstrating that modern Monte-Carlo simulation techniques can be used to design radiation monitors and to optimize their performance.
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WEOBCH02 | Design, Construction, and Initial Operation of the SNS MEBT Chopper System | focusing, kicker, bunching, beamloading | 150 | ||||||
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The chopper system for the Spallation Neutron Source (SNS) provides a gap in the beam for clean extraction from the accumulator ring. It consists of a pre-chopper in the low-energy beam transport (LEBT) and a faster chopper in the medium-energy beam transport (MEBT). We report here on the final design, fabrication, installation, and first beam tests of the MEBT chopper. The traveling-wave deflector is a meander-line design that matches the propagation of the deflecting pulse with the velocity of the beam at 2.5 MeV, after the radio-frequency quadrupole (RFQ) acceleration stage. The pulser uses a series of fast-risetime MOSFET transistors to generate the deflecting pulses of ± 2.5 kV with rise and fall times of 10 ns. We describe the design and fabrication of the meander line and pulsers and report on the first operation during initial beam tests at SNS.
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WEOCCH01 | A New 180 MeV H- Linac for Upgrades of ISIS | focusing, kicker, bunching, target | 153 | ||||||
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Several options have been studied to raise the beam power of the ISIS spallation neutron source to a level of 1 MW with the possibility of going to 4-5 MW in the longer term. All scenarios can operate in 2 modes, where the beam power is either delivered to a spallation target or, alternatively, to a target suitable to produce muons via pion decay for a neutrino factory. A more recent upgrade option takes an intermediate step and uses a 180 MeV H- linac, which is also foreseen for the 4-5 MW upgrade, as a replacement for the current 70 MeV injector. First estimates indicate that, due to the lower space charge forces, the ring would be able to carry twice as many particles, thus doubling the final beam power to 0.5 MW. This paper presents a first design for the 180 MeV linac, using a triple frequency jump from 234.8 to 704.4 MHz. The design profits from the development of 704.4 MHz cavities and RF equipment within the framework of the European HIPPI collaboration. The low frequency for the front-end was chosen to ease the DTL design as well as the development of a low energy beam chopper, which will be necessary to reduce beam losses at injection into the synchrotron.
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WEOCCH02 | Construction Status and Issues of the Spallation Neutron Source Ring | focusing, kicker, bunching, target | 156 | ||||||
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(For the Spallation Neutron Source collaboration) The Spallation Neutron Source (SNS) accelerator complex is now in its sixth year of a seven-year construction cycle. The design, fabrication, test, and assembly of the accumulator ring and its transport lines is approaching the final stage. In order to reach the design goal of this high-power ring to deliver 1.5 MW beam power (1.5$× 1014 protons of 1 GeV kinetic energy at a repetition rate of 60 Hz), stringent measures have been implemented to ensure the quality of the accelerator systems. This paper reviews the progress of the ring and transport systems with emphasis on the challenging technical issues and their solutions inccurred during the construction period.
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WEODCH01 | 1.5-GeV FFAG Accelerator as Injector to the BNL-AGS | focusing, acceleration, kicker, bunching | 159 | ||||||
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A 1.5-GeV Fixed-Field Alternating-Gradient (FFAG) Accelerator has been recently proposed as a new injector to the Alternating-Gradient Synchrotron (AGS) of Brookhaven National Laboratory (BNL). It is being considered as a replacement of the present 1.5-GeV AGS Booster. The substitution will enhance the performance of the AGS accelerator facility in a variety of ways. It would still allow acceleration of all hadronic particles: protons, and heavy-ions. The major benefit is that it would considerably shorten the typical combined AGS acceleration cycle, and, consequently, may yield to an improvement of beam stability, intensity and size. The AGS-FFAG will also facilitate the proposed upgrade of the AGS facility toward a 1-MW average proton beam power. The paper describes a compact FFAG design for acceleration of protons from 200 MeV to 1.5 GeV. The circumference is about 250 m. The lattice is a periodic sequence of FDF triplets of combined-function magnets. An adjusted field profile has been calculated to compensate the variation of the main lattice functions with momentum. At injection, a beam pulse 130 μs long of negative-ions (H?) is stacked with the charge-exchange method. Acceleration of one pulse with 2.5 x 1013 protons takes about 130 μs, if harmonic-jump scheme is used in conjunction with the choice of 201.25 MHz. Four of such beam pulses are required to fill entirely the AGS. The entire filling process thus takes less than one millisecond.
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WEODCH02 | Interaction of Stored Ions with Electron Target in Low Energy Electrostatic Ring | electron, focusing, ion, kicker | 162 | ||||||
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The KEK electrostatic ring is used for investigations of molecular, bimolecular and DNA ions. The electron target installed in this ring has same construction as usual electron cooler. The interaction of stored ions with the electrons increases the ion lifetime at electron cooling caused by a suppression of the ion scattering on the residual gas atoms. The proton lifetime of 2 s was increased in the experiments by factor 2 at the electron cooling with the electron beam current of 0.2 mA, the proton energy of 20 keV and the residual gas pressure of 0.04 nTorr. However the electron-ion interaction can decrease the ion lifetime caused by an excitation of the transverse instability produced by an intensive electron beam. So in the KEK electrostatic ring the proton lifetime is reduced to 1.7 s at detuning of electron acceleration voltage from nominal cooler value on 0.4 V. The simulation of electron cooling and transverse instability of the light and DNA ions are discussed in this report.
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WEXLH01 | Non-destructive Beam Measurements | electron, focusing, ion, kicker | 165 | ||||||
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In high energy accelerators especially storage rings, non-destructive beam measurements are highly desirable to minimize the impact on the beam quality. In principle, the non-destructive tools can be either passive detectors like Schottky, or active devices which excite either longitudinal or transverse beam motions for the corresponding measurements. An example of such a device is ac dipole, a magnet with oscillating field, which can be used to achieve large coherent betatron oscillations. It has been demonstrated in the Brookhaven AGS that by adiabatically exciting the beam, the beam emittance growth due to the filamentation in the phase space can be avoided. This paper overviews both techniques in general. In particular, this paper also presents the beam tune measurement with Schottky detector, phase advance measurement as well as non-linear resonance measurements with the ac dipoles in the Brookhaven RHIC.
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WEOALH01 | Particle-in-cell Beam Dynamics Simulations | electron, focusing, ion, kicker | 170 | ||||||
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We describe the application of the Conformal Finite Integration Technique (CFIT) in the time-domain to beam dynamics simulations with the Particle-In-Cell (PIC) method. The conformal method results in a more accurate field solution for complicated geometries than the traditional FIT approach. For long-time simulations we investigate several methods for the suppression of the spurious noise, typically emerging in PIC simulations. The results are compared with the analytical solution for a bunch in a semi-infinite waveguide for each of the presented methods. As a realistic example simulations for the RF-Gun installed at Photo Injector Test Facility in DESY Zeuthen (PITZ) will be presented.
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WEOALH02 | Multiturn Extraction Based on Trapping in Stable Islands at CERN PS: Recent Measurement Advances | electron, focusing, ion, kicker | 173 | ||||||
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Recently a novel approach to perform multi-turn extraction was proposed based on beam splitting in the transverse phase space by means of trapping inside stable islands. During the year 2002 run, preliminary measurements at the CERN Proton Synchrotron with a low-intensity, single-bunch, proton beam, confirmed the possibility of generating various beamlets starting from a single Gaussian beam. The experimental campaign continued also in the year 2003 run to assess a number of key issues, such as feasibility of trapping with high-intensity beam, capture efficiency, and multi-turn extraction proper. The experimental results are presented and discussed in detail in this paper.
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WEOALH03 | Installation Strategy for the LHC Main Dipoles | electron, focusing, ion, kicker | 176 | ||||||
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All positions in the LHC machine are not equivalent in terms of beam requirements on the geometry and the field quality of the main dipoles. In the presence of slightly or strongly out-of tolerance magnets, a well-defined installation strategy will therefore contribute to preserve or even optimize the performance of the machine. In view of present state of the production, we have anticipated a list of potential issues (geometry, transfer function, field direction and random b3) which, combined by order of priority, have been taken into account to define a robust installation algorithm for the LHC main dipoles. Among the different possible strategies, the proposed one has been optimised in terms of simplicity and flexibility in order not to slow down and complicate the installation process. Its output is a prescription for installing the available dipoles in sequence while reducing to an absolute minimum the number of holes required by geometry or field quality issues.
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WEPKF041 | Permanent Magnet Generating High and Variable Septum Magnetic Field and its Deterioration by Radiation | alignment, kicker, bunching, septum | 1696 | ||||||
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Conventional high field septum magnet is fed by DC current or pulse current. In the case of DC, the problem of coil support is not very important, but the cooling of the coil is serious problem. While, in the case of pulse, the problem of support is much important than that of cooling. However, if the septum magnet is made of permanent magnet, those problems are dissolved. And the cost for electricity and cooling water can be exceedingly decreased. Therefore, we made the model septum magnet which has 1/4 scale of the real size and generates 1[T] with the variable range of ± 10%. The magnetic field distribution in the gap by changing the representative field is reported. When this permanent magnet is set in an accelerator, the deterioration of the permanent magnet by radiation will be serious problem. We also report the dependence of the magnetic fields generated by permanent magnet samples on accumulated radiation by various types of radiation source.
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WEPKF042 | Installation and Operation of New Klystron Power Supply with Fast Solid-State Switch for Klystron Protection at the Photon Factory Storage Ring | alignment, kicker, bunching, septum | 1699 | ||||||
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In the 2.5-GeV Photon Factory storage ring at KEK, there are four klystron power supplies which typically operate at an output voltage of -40 kV with 8 A. We replaced one of these power supplies during 2003 and the new power supply is in operation. This power supply is equipped with a solid-state high-voltage (HV) switch for klystron protection. This HV switch is made up of eighty insulated gate bipolar transistors (IGBT), and it can turn the high-voltage off within a few tens of microseconds in cases of any discharges in the klystrons. We report the performance of this new power supply.
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WEPKF043 | Measurement of the Vertical Quadrupolar Tune Shift in the Photon Factory Storage Ring | alignment, kicker, bunching, quadrupole | 1702 | ||||||
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We measured the frequencies of vertical quadrupole oscillations in the 2.5-GeV Photon Factory storage ring at KEK. The measured vertical quadrupole tunes showed remarkable dependence of about -7.5E-5/mA on the bunch current. This contrasts with our previous result of about +4.8E-5/mA (presented in PAC2003) for the horizontal quadrupole tune shift. These results will suggest that the transverse wake forces in a quadrupolar mode contribute significantly to the transverse motions of particles in the Photon Factory storage ring.
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WEPKF046 | Gradient Field Generation in a Uniform Gapped Magnet | alignment, kicker, bunching, quadrupole | 1705 | ||||||
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Magnets with gradient field (indexed magnets) usually have different gap distances with the different entrance positions. This situation will break a uniformity of the effective length. Trim coils, which are usually used in Cyclotron, are not practical to modify a field distribution when a large gradient is required such as FFAG. In order to generate a gradient field in a constant gapped magnet, a novel method with use of inter-pole is devised. This magnet has not only constant gap but also smaller fringing field compared with a conventional one. This technique should widen the recipe to design a magnet with such a complex magnetic field.
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WEPKF047 | A Super Strong Adjustable Permanent Magnet for the Final Focus Quadrupole in a Linear Collider | alignment, kicker, bunching, quadrupole | 1708 | ||||||
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A super strong magnet, which utilizes permanent magnet material and saturated iron, is considered as a candidate for the final focus quadrupole in a linear collider beamline. This modified Halbach magnet configuration can have a higher magnetic field gradient than a normal permanent magnet quadrupole (PMQ) or electromagnet. There are some issues to be solved if a PMQ is to be used as a final focus quadrupole: the variation of its strength with temperature and the need for the field strength to be deliberately changed. One can use special temperature compensation material to improve the temperature dependence with just a small decrease in field gradient compared to a magnet without temperature compensation. The required field variability can be obtained by slicing the magnet into pieces along the beamline direction and rotating these slices. Results of performance measurements on the PMQ with variable strength will be reported including the realization of the temperature compensation technique.
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WEPKF048 | Characteristics of Ground Motion at KEK and SPring-8 | alignment, kicker, bunching, site | 1711 | ||||||
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Authors Y. Nakayama, T. Ito, (JPOWER); R. Sugahara, S. Takeda, H.Yamaoka, M.Yoshioka (KEK); S.Matsui, C.Zhang (SPring-8); S. Yamashita (ICEPP): Abstract Stability of ground is preferable for accelerator beam operation. We have measured ground motion of ground at the KEKB and SPring-8 site, where the ground has quite different characteristics each other. In this paper, some of analysis results are shown, and the characteristics of the ground motion at the KEKB site and those at the Spring-8 site are compared.
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WEPKF049 | Stretched Wire Flip Coil System for Magnetic Field Measurements | alignment, kicker, bunching, site | 1714 | ||||||
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A flip-coil system using a stretched wire measuring the magnetic field properties of accelerator magnets is described. This system is similar to the conventional rotating coil system except that the stretched wires are used instead of wires wound on the machined surface. This system has advantage of simple fabrication and flexible operation so that different length and bore magnets can be easily measured using the same system. The system also has two loop coils to buck the dominant fundamental field so as to increase the measurement accuracy. This kind of system has issues related to the reproducibility, accuracy of the measured results. The system is evaluated to verify its performances and its results were discussed. The analyzing methods and various efforts to keep the system in high accuracy are presented. Measurement results with this loop coil system were compared with that of the other system.
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WEPKF050 | Measurement of Fast High Voltage Pulse and High Noisy DC Siganla for Modulator at the PLS Linac | alignment, kicker, bunching, site | 1717 | ||||||
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The 2.5-GeV electron linac at Pohang accelerator laboratory (PAL) has been operated continuously as a full energy injector for the Pohang Light Source (PLS) since Dec. 1994. There have been continuous efforts to improve the klystron-modulator system more stable and reliable. At pulse operated modulator system, important pulse and DC signals are beam voltage, beam current, EOLC current HVDC voltage and HVDC current. Pulse signals are fast high voltage pulse 30 Hz, 5ms. These signals are adequate level down from modulator but including high level switching noisy. To amplitude measure of these signals for every trigger signal, we developed special module sampling hold, A/D, calculating and D/A. The output signals of these modules are 0 ~ 10 V DC signal and not include any noise signal. These output signals are connected interlock interface module of the modulator controller. Therefore computer system (PC) of the modulator controller is free to noise of these signals and can precise monitor pulse & noise DC signal. In these paper, we are described itself characteristics pulse and high noisy DC signals of the modulator, signal conditioning technique after noise elimination and operation status of the modulator controller.
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WEPLT033 | The LHC Radiation Monitoring System for the Environment and Safety | focusing, acceleration, resonance, booster | 1900 | ||||||
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A state of the art radiation monitoring and alarm system is being implemented at CERN for the LHC. The RAdiation Monitoring System for the Environment and Safety (RAMSES) comprises about 350 monitors and provides ambient dose equivalent rates measured in the LHC underground areas as well as on the surface inside and outside the CERN perimeter. In addition, it monitors air and water released from the LHC installations. Although originally conceived for radiation protection only, RAMSES also integrates some conventional environmental measurements such as physical and chemical parameters of released water and levels of non-ionizing radiation in the environment. RAMSES generates local radiation warnings, local alarms as well as remote alarms on other monitored variables, which are transmitted to control rooms. It generates operational interlocks, allows remote supervision of all measured variables as well as data logging and safe, long-term archiving for off-line data analysis and reporting. Requirements of recent national and international regulations in combination with CERN's specific technical needs were translated into the RAMSES specifications. This paper outlines the scope, the organization, the main system performance and the system design.
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WEPLT035 | Capture Loss of the LHC Beam in the CERN SPS | focusing, acceleration, resonance, booster | 1903 | ||||||
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The matched voltage of the LHC beam at injection into the SPS is 750 kV. However, even with RF feedback and feed forward systems in operation, the relative particle losses on the flat bottom for nominal LHC parameters with this capture voltage can reach the 30% level. With voltages as high as 2 MV these losses are still around 15% pushing the intensity in the SPS injectors to the limit to obtain nominal intensity beam for the LHC. Beam losses grow with intensity and are always asymmetric in energy (lost particles are seen main in front of the batch). The asymmetry can be explained by the energy loss of particles due to the SPS impedance which is also responsible for a non-zero synchronous phase on the flat bottom leading to large gaps between buckets. In this paper the measurements of the dependence of particles loss on the beam and machine parameters are presented and discussed together with possible loss mechanisms.
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WEPLT036 | Energy Loss of a Single Bunch in the CERN SPS | focusing, acceleration, resonance, booster | 1906 | ||||||
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The dependence of energy loss on bunch length was determined experimentally for a single proton bunch in the SPS at 26 GeV/c. This was done from measurements of the synchronous phase as a function of intensity for different capture voltages. The results are compared with the expected dependence calculated from the resistive part of the SPS impedance below 1 GHz. Two impedance sources, the cavities of the 200 MHz RF system and the extraction kickers, give the main contributions to particle energy loss in very good agreement with experiment. The results obtained allow a better understanding of some mechanisms leading to capture loss of the high intensity LHC beam in the SPS.
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WEPLT037 | A J2EE Solution for Technical Infrastructure Monitoring at CERN | focusing, acceleration, resonance, booster | 1909 | ||||||
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The Technical Infrastructure Monitoring project (TIM) will design and implement the future control system for CERN's technical infrastructure. The control system will be built using standard components including industrial PLCs, Java Enterprise Edition (J2EE) including Enterprise Java Beans and the Java Message Service and relational databases. This paper describes how these standard technologies are used to build a flexible, scalable, robust and reliable control system.
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WEPLT038 | Betatron Resonance Studies at the CERN PS Booster by Harmonic Analysis of Turn-by-turn Beam Position Data | resonance, focusing, acceleration, bunching | 1912 | ||||||
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High brightness and high intensity beams are required from the PS Booster for LHC, CNGS and ISOLDE operation. The large space charge tune spreads associated with these beams, especially at injection, require an optimized resonance compensation scheme to avoid beam blow-up and subsequent beam losses. For this a detailed knowledge on strength and phase of resonance driving terms is needed. A new measurement system has been installed to determine resonance driving terms from turn-by-turn bpm data using fast Fourier transform. The multi-turn acquisition system as well as the specific measurement conditions at the PS Booster are discussed. As an example, the measurement and compensation of the linear coupling resonance driving term is presented. Excellent agreement between measurement and simulation for resonance phase and strength was found.
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WEPLT039 | Measurement and Compensation of Second and Third Order Resonances at the CERN PS Booster | focusing, acceleration, resonance, bunching | 1915 | ||||||
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Space charge effects at injection are the most limiting factor for the production of high brightness beams in the CERN PS Booster. The beams for LHC, CNGS and ISOLDE feature incoherent tune spreads exceeding 0.5 at injection energy and thus cover a large area in the tune diagram. Consequently these beams experience the effects of transverse betatron resonances and efficient compensation is required. Several measurements have been performed at the PS Booster in 2003, aiming at a detailed analysis of all relevant second and third order resonances and an optimisation of the compensation scheme. Special attention was paid to the systematic 3Qy=16 resonance. To avoid this particularly dangerous resonance an alternative working point was tested. A comparison of resonance driving terms and compensation settings for both working points was made and important differences in the strengths of the resonances were found. The peculiarities when measuring third order coupling resonance driving terms are also mentioned.
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WEPLT040 | Layout Drawings of the LHC Collider | focusing, acceleration, resonance, bunching | 1918 | ||||||
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The team in charge of the LHC integration largely uses 3D scenes combining functional positions of equipments and the 3D CAD model issued from the Cern Drawing Directory (CDD) repository. This is made possible through the Digital Mock-Up tool developed at CERN. Giving dimensions in 3D context is a challenge with the current 3D CAD tools used at CERN. Requirements from users groups have made clear a need for automatic production of 2D layout drawings. This paper presents the retained solution to create on-request dimensioned drawings, to publish them, while maintaining coherence and consistency with the 3D integration scenes. Reliability of the information, on-line availability of the latest layout changes on dimensions and positions of equipments, and the maintenance of the facility will also be described.
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WEPLT041 | RF Amplitude Modulation to Suppress Longitudinal Coupled Bunch Instabilities in the SPS | focusing, resonance, bunching, booster | 1921 | ||||||
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In the SPS, even after a considerable impedance reduction including the removal of all RF cavities used for lepton acceleration in the past, longitudinal coupled bunch instabilities develop with an LHC beam of about one fifth of the nominal bunch intensity. The nominal LHC beam is stabilised using both, the 800 MHz Landau damping cavities, in bunch shortening mode, and pre-emptive emittance blow-up. An alternative method to increase the synchrotron frequency spread and thus stabilise the beam is amplitude modulation of the accelerating RF voltage. This method might be especially suitable in accelerators without a higher harmonic RF system, as will be the case in LHC. The main results of recent studies using this method in the SPS and considerations about its use in LHC are presented.
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WEPLT042 | Scheduling the Installation of the Large Hadron Collider | focusing, resonance, bunching, booster | 1924 | ||||||
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The size and complexity of the LHC project at CERN calls for a strong co-ordination of all installation activities. The detailed installation planning has to take into account many constraints such as the component production rates, the installation contracts or the transport and handling requirements in a narrow tunnel with limited access points. The planning also needs to be flexible enough to cope with aleas that are unavoidable in such a large project that spans over many years. This paper describes the methodology followed by the team responsible for the planning and logistics in order to stay reactive to the actual progress of the installation and to keep optimizing the usage of resources.
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WEPLT043 | Detecting Failures in Electrical Circuits Leading to Very Fast Beam Losses in the LHC | focusing, resonance, bunching, booster | 1927 | ||||||
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Depending on the beam optics, failures in the magnet powering at locations with large beta functions could lead to very fast beam losses at the collimators, possibly within less than 10 turns. Beam loss monitors would normally detect such losses and trigger a beam dump. However, the available time for detection with beam loss monitors before reaching the damage level of a collimator might not be sufficient, in particular for beams with few particles in the tails. This has always been of concern and becomes even more relevant since very fast losses have been observed recently at HERA. In this paper, we present particle tracking studies for the LHC to identify failures on critical magnets. We propose a fast detection of such failures in the electrical circuit, either with highly precise hall probes for current measurement or measurements of the induced inductive voltage during the current decay. In combination with a small and simple interlock electronics such detection system can provide reliable and fast interlock signals for critical magnets in the LHC main ring but could also be used to monitor injection and extraction magnets. Depending on the properties of the electrical circuit an increase of the natural time constant of the current decay using a serial superconducting magnet is also considered.
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WEPLT044 | Electron-cloud Build-up Simulations and Experiments at CERN | focusing, resonance, bunching, electron | 1930 | ||||||
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We compare the predications of electron-cloud build-up simulations with measurements at the CERN SPS. Specifically, we compare the electron flux at the wall, electron-energy spectra, heat loads, and the spatial distribution of the electrons for two different bunch spacings, with variable magnetic fields, and for several chamber temperatures and associated surface conditions. The simulations employ a modified, improved version of the ECLOUD code. The main changes are briefly described. We finally present updated simulation results for the heat load in the cold LHC arcs.
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WEPLT045 | Experiments on LHC Long-range Beam-beam Compensation in the CERN SPS | focusing, resonance, bunching, electron | 1933 | ||||||
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Long-range beam-beam collisions may limit the dynamic aperture and the beam lifetime in storage-ring colliders. Their effect can be compensated by a current-carrying wire mounted parallel to the beam. A compensation scheme based on this principle has been proposed for the Large Hadron Collider (LHC). To demonstrate its viability, a prototype wire was installed at the CERN SPS in 2002. First successful machine experiments explored the dependence of beam loss, beam size, and beam lifetime on the beam-wire distance and on the wire excitation. They appear to confirm the predicted effect of the long-range collisions on the beam dynamics. In 2004, two further wires will become available, by which we can explicitly demonstrate the compensation, study pertinent tolerances, and also compare the respective merits of different beam-beam crossing schemes for several interaction points.
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WEPLT046 | Localizing Impedance Sources from Betatron-phase Beating in the CERN SPS | focusing, resonance, bunching, impedance | 1936 | ||||||
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Multi-turn beam-position data recorded after beam excitation can be used to extract the betatron-phase advance between adjacent beam position monitors (BPMs) by a harmonic analysis. Performing this treatment for different beam intensities yields the change in phase advance with current. A local impedance contributes to the average tune shift with current, but, more importantly, it also causes a mismatch and phase beating. We describe an attempt to determine the localized impedance around the SPS ring by fitting the measured betatron phase shift with current at all BPMs to the expected impedance response matrix.
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WEPLT047 | A Test Suite of Space-charge Problems for Code Benchmarking | focusing, resonance, bunching, impedance | 1939 | ||||||
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A set of problems is presented for benchmarking beam dynamics codes with space charge. As examples, we show comparisons using the IMPACT, MaryLie/IMPACT, and MAD9P codes. The accuracy and convergence of the solutions as a function of solver algorithms, simulations parameters such as number of macro particles, grid size, etc. are studied.
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WEPLT048 | Beam Dynamic Studies of the 72 MeV Beamline with a 'Super Buncher' | focusing, resonance, bunching, impedance | 1942 | ||||||
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A significant increase of the beam intensity increase of the PSI 590 MeV proton accelerator facility above 2 mA requires a higher accelerating voltage in the main RF cavities. A corresponding increase of the voltage in the flattop cavity would result in a complete rebuild of this device. As an alternative, a scheme with a strong buncher in the 72 MeV beam transfer line is being studied. The goal is to restore the narrow phase width (~ 2 deg/RF at 50 MHz) of the beam bunches observed at extraction from Injector 2 at injection into the Ring Cyclotron. If we can find and inject a stable particle distribution, as done in the Injector 2, the flat-top cavity might eventually be decommissioned. First results of multi particle tracking in full 6 dimensional phase space with space charge are presented.
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WEPLT049 | Timekeeping Mechanism at SLS/APS Control System | focusing, resonance, bunching, impedance | 1945 | ||||||
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Time is one of the most important and critical parameters in a distributed control and measurement system. It is especially crucial when we need to interpret correlation of different archived process variables (PV) during the time. Advanced Light Source (APS) and Swiss Light Source (SLS) are using a very similar control system toolkit (EPICS) and the same mechanism for timekeeping. Many input/output controllers (IOC) around the accelerator complex (including beamlines), run under a real-time operating system, and carry out the controls and data acquisition. Each IOC is responsible of keeping its own local time and time-stamps the local PV?s but tightly synchronized with a central timing IOC. Dedicated timing hardware and network makes it possible to maintain synchronous timestamps with real-time clock. In this paper we describe the principle of this mechanism, its advantages, our experiences and further improvements.
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WEPLT050 | Frequency Map Measurements at BESSY | focusing, resonance, bunching, impedance | 1948 | ||||||
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With two dedicated diagnostic kicker magnets and a turn-by-turn, bunch-by-bunch beam position monitor frequency maps were measured under various operating conditions of the BESSY storage ring. Depending on the number and type of insertion devices in operation additional resonances show up. Details of the experimental setup as well as the data analysis are presented. The results will be compared with theoretical calculations which are based on the linear model of the storage ring lattice extracted from measured response matrices. Non-linear elements are added to the model in order to describe the effect of the strong sextupole magnets, the horizontal corrector magnets installed in these magnets, and of some of the insertion devices.
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WEPLT103 | Radiation Damage in Magnets for Undulators at Low Temperature | antiproton, plasma, vacuum, booster | 2089 | ||||||
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Nd2Fe14B permanent magnets are used in many insertion devices for its good magnetic and mechanical properties. However, the radiation sensitivity of the magnets would be concern when they are used in a strong radiation environment. It is known that these magnets with very high coercivity show high resistance to radiation, though the substance for increasing the coercivity decrease the remanence. The coercivity and remanence of this magnet exhibit negative dependence against temperature, so it is expected to these magnets to show high remanence and high resistance to radiation at low temperature. The idea of using magnets at low temperature leads the new concept of the cryogenic undulators. In this report, the experimental results of the radiation damage of permanent magnets at low temperature are shown.
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WEPLT105 | Beam-Beam Effects Measured Using Gated Monitors at KEKB | antiproton, plasma, vacuum, electron | 2092 | ||||||
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KEKB is a multi-bunch, high-current, electron/positron collider for B meson physics. The two beams collide at one interaction point (IP) with a finite horizontal crossing angle and with a bunch-space of 6 to 8 ns. The luminosity of KEKB is the best in the world. The collision is performed by carefully adjusting a horizontal orbit bump of the electron beam at IP, which results in a horizontal offset to obtain the best luminosity. In order to investigate the asymmetric beam-beam effects, beam parameters of collision and non-collision bunches were compared using beam monitors capable of selecting a specific bunch in a bunch train. The beam-beam kick and the beam-beam tune-shift were obtained by the gated beam-position monitor and by the gated tune monitor. It was found that the horizontal offset was negligibly small in the case of a wide bunch-space of 48 ns. This result suggests that the horizontal offset is related to wake fields including electron-cloud effects.
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WEPLT106 | Growth and Suppression Time of an Ion-related Vertical Instability | antiproton, plasma, octupole, booster | 2095 | ||||||
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In the KEK Photon Factory electron storage ring, a vertical instability has been observed in a multi-bunch operation mode. The instability can be suppressed by octupole magnetic field in routine operation. Since the instability depends on a vacuum condition in the ring, it seems that it is an ion-related phenomenon. In order to study this instability, we measured the growth and the suppression time of it with the pulse octupole magnet system, which can produce the octupole field with rise and fall time of around 1.2msec. We obtained the result that the instability was grown slowly compared with to suppress it, and the growth time depended on the fill pattern of the bunch train and the beam current per bunch.
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WEPLT107 | Nonlinear field Effects in the JPARC Main Ring | sextupole, antiproton, plasma, proton | 2098 | ||||||
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Main Ring (MR) of the Japanese Particle Accelerator Research Complex (JPARC) should provide acceleration of the high-intensity proton beam from the energy of 3GeV to 50 GeV. The expected beam intensity is 3.3·1014 ppp and the repetition rate is about 0.3 Hz. The imaginary transition lattice of the ring was adopted, which has the natural linear chromaticity about (-30) for both transverse phase planes. The expected momentum spread of the captured particles before the acceleration is less than 0.007. Two independent families of the chromatic sextupole magnets are use to eliminate the linear chromatic tune shift. This chromatic sextupole field nonlinearity will excite the normal 'octupole' resonances and will lead to the amplitude dependent tune shifts in both transverse phase planes. Additional sextupole magnets are planed to excite the third-order horizontal resonance, which will be used for the slow extraction. Incoherent tune shift of the low-energy proton beam is about (-0.16) so that some particles could cross nearest low-order resonances. Optimization of the 'bare' working point of MR at the injection energy has been performed to minimize the influence of the linear coupling and high-order coupling resonances. Excitation of the linear coupling resonance has been introduced by the realistic misalignment errors adopted for MR. The 'bare' working point during the slow extraction has been analyzed. The influence of the normal sextupole resonances on the large amplitude particle behavior at the scraper location has been studied including random sextupole field component of the MR bending magnets. Realistic distortion of the ideal ring super-periodicity by the injection kicker magnets has been included in the tracking procedure for the on- and off-momentum particles. Finally, correction schemes have been considered for most dangerous resonances around the optimized 'bare' working point. The space-charge effects of the proton beam have not been included in this study.
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WEPLT108 | Diffusion caused by Beam-beam Interactions with Couplings | sextupole, antiproton, plasma, proton | 2101 | ||||||
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A system of colliding two beams is strong nonlinear in multi-dimension. In such a system, a symplectic diffusion called Arnold diffusion occurs, with the result that the beams are enlarged and the luminosity is degraded in circular colliders. We discuss the diffusion seen in beam-beam inetraction at a circular accelerator, especially finite crossing angle and/or x-y coupling errors enhance the diffusion.
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WEPLT109 | Simulation of Ep Instability for a Coasting Proton Beam in Circular Accelerators | sextupole, antiproton, plasma, booster | 2104 | ||||||
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ep instability is discussed for a coasting beam operation of J-PARC 50 GeV Main Ring. Our previous study (PAC2003) was focussed only ionization electron. We now take into account electrons created at the chamber wall due to proton loss and secondary emission with higher yield than ionization.
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WEPLT110 | Specific Beam Dynamics in Super-bunch Acceleration | sextupole, antiproton, plasma, booster | 2107 | ||||||
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Proof-of-principle experiments on the induction synchrotron concept using the KEK 12-GeV PS makes progress, in which RF bunches and a super-bunch will be accelerated with a long step voltage generated in the induction accelerating gaps. In order to give a guide for super-bunch acceleration, the beam stabilities against a droop and a fluctuation of the accelerating voltage have been examined by using a simulation. The droop voltage gives an additional focusing or defocusing force in the longitudinal direction, which leads the mismatching beyond the transition energy. Furthermore, the extremely slow fluctuation of the accelerating voltage causes a lowest-order resonance near the transition. These induce a serious emittance blow-up in the longitudinal, so that the compensating manners will be presented. Moreover, the other issues such as head-tail instability and intra beam scattering will be discussed.
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WEPLT113 | Development of New Hydrostatic Levelling Equipment for Large Next Generation Accelerator | sextupole, antiproton, plasma, booster | 2110 | ||||||
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The Hydrostatic Levelling Systems (HLS) are installed and commissioned in many laboratories. We have developed a new type hydrostatic levelling equipment for the large future accelerator. The designing points are as followings: (1) use of half filled water level sensor instead of the usual full filled level sensor, (2) the capacitive sensor is supported by an invar rod and (3) use of digitized signal transfer system. These three points are very important factor to apply the leveling system to large next generation accelerator in order to obtain good temperature stability and being free from the environmental electronic noises. We have obtained a typical resolution of the equipment as 0.3 micron-meter, though usual HLS shows the value ten times as much. We are going to show a detailed report about the system including data obtained.
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WEPLT114 | Field Measurements in the AGS Warm Snake | sextupole, antiproton, plasma, booster | 2113 | ||||||
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A new warm snake has been produced for avoiding the transverse coupling resonance in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). The warm snake is the world?s first normal conducting helical dipole partial snake which has a double pitch structure to allow spin rotation with no net beam offset or deflection with a single magnet. The warm snake is 2.6m long, and has a field of 1.5 Tesla for a 9 degrees spin rotation. The pitches, current density, and shims were optimized by using OPERA_3D / TOSCA. The magnetic field harmonics have been measured using a system of 51 mm long, 34 mm radius tangential coils. The axial variation of the dipole field angle agrees very well with the calculations, indicating no significant construction errors. However, the measured transfer function shows a discrepancy of 4% which may be caused by BH-curve differences, deformation of the iron and packing factor of the laminations. To correct the beam trajectory the operating current was adjusted and shims were installed on the end plates. These optimization studies, and comparison with measurements, will be shown.
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WEPLT115 | A Study of Transverse Resonance Crossing in FFAG | sextupole, antiproton, plasma, resonance | 2116 | ||||||
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A study of "resonance crossing" in FFAG accelerator is described in this paper. A deviation of FFAG guiding field in actual magnet breaks zero chromaticity condition, and tunes cross resonance while acceleration. In order to avoid a critical beam loss or emittance growth, nominal tune should be chosen so as not to cross low-order resonances. However, crossing higher order resonance can be critical and that depends on the parameters such as crossing speed, excitation magnitude and initial beam emittance. We will present analytical model and simulation study in various parameter space.
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WEPLT116 | Lattice Design and Cooling Simulation at S-LSR | sextupole, antiproton, plasma, resonance | 2119 | ||||||
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A compact ion cooler ring, S-LSR is under construction in Kyoto University. The circumference is 22.557 m and the maximum magnetic rigidity is 1 Tm. One of the important roles of S-LSR is a test bed to examine the lowest temperature limit of the ion beams using cooling techniques. The ultimate case is a crystalline one. The ring optics of S-LSR has a high super periodicity and a low phase advance to reduce the beam heating from the lattice structure. S-LSR has an electron beam cooling device and a laser cooling system for Mg. The simulation results show the possible limit of the ion beam temperature and the dependence on the operating betatron tunes.
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WEPLT117 | Design of a Third Harmonic Superconducting RF System at PLS | sextupole, antiproton, plasma, resonance | 2122 | ||||||
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A superconducting third harmonic rf system has been designed in the PLS to raise beam lifetime. Expected beam lifetimes verse beam emittance and operational beam current are presented. A multibunch multiparticle tracking simulation is performed to investigate energy spread, bunch-lengthening and beam instabilities due to the rf cavities. The parameters of the designed rf cavity, designed cryogenic system and estimation of heat load are also presented.
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WEPLT118 | Performance of the TU/e 2.6 Cell Rf-photogun in the 'Pancake' Regime | sextupole, antiproton, resonance, ion | 2125 | ||||||
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The 2.6 cell rf-photogun currently in operation at Eindhoven University of Technology has been designed as a booster for a 2 MeV semi-DC accelerator with a field of 1 GV/m. In this paper we present GPT simulation results of the TU/e gun, operated without its pre-accelerator, in the low-charge short-pulse regime. The main part of the paper describes detailed calculations of bunch lengthening due to path-length differences and space-charge effects, making use of high-precision field-maps and the newly developed 3D mesh-based space-charge model of GPT. It is shown that with the present set-up bunches can be produced that are well suited for injection into a planned experiment for controlled acceleration in a plasma-wakefield accelerator.
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WEPLT119 | Beam Instabilitiy Studies of BEPC and BEPCII | sextupole, antiproton, resonance, ion | 2128 | ||||||
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BEPC has been well operated for more then 10 years, and it will be upgraded to a double ring electron positron collider using the existing tunnel, namely BEPCII. This paper describes the recent studies on beam instabilities in BEPC for the improvement of its performance as well as for BEPCII. The instabilities caused by impedance and two-stream effect are investigated. The experimental and simulation results are reported.
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WEPLT120 | Control Environment for the Superconducting Insertion Devices at NSRRC | sextupole, insertion, antiproton, resonance | 2131 | ||||||
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To enhance hard X-ray capability in the 1.5 GeV storage ring of NSRRC to serve the rapidly growing X-ray user community in Taiwan, the storage ring was installed two superconducting insertion devices. Three more superconducting insertion devices are in planning. A 6 Tesla superconducting wavelength shifter was installed in mid-2002. A 3.2 Tesla superconducting multi-pole wiggler was installed in December of 2003. Control system and operation environment have been set up to support the operation of the superconducting insertion devices. The implementation and operation experiences will be summarized in this report.
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WEPLT121 | Computer Simulation of Equilibrium Electron Beam Distribution in the Proximity of 4th Order Single Nonlinear Resonance | sextupole, insertion, antiproton, resonance | 2134 | ||||||
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The beam distribution of particles in an electron storage ring is distorted in the presence of nonlinear resonances. A computer simulation is used to study the equilibrium distribution of an electron beam in the presence of 4th order single nonlinear resonance. The results are compared with that obtained using an analytical approach by solving the Fokker-Planck equation to first order in the resonance strength. The effect of resonance on the quantum lifetime of electron beam is also compared and investigated.
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WEPLT122 | Investigation of Microwave Instability on Electron Storage Ring TLS | sextupole, antiproton, resonance, ion | 2137 | ||||||
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With the planned installation of a superconducting rf system, the new operation mode of TLS, the electron storage ring at NSRRC, is expected to double the beam intensity. Several accelerator physics topics need to be examined. One of these topics concerns the beam instability of single-bunch longitudinal microwave instability. We consider different approaches to measure the effective broad band impedance. We compare these measurement results with each other and to the old data [*]. The new measurements of effective broad band impedance are higher than the old measurement since between these two sets of measurements several narrow gap insertion devices were installed into the storage ring. We calculate the threshold current of microwave instability with a mode-mixing analysis code written by Dr. K. Oide of KEK [**]. We also develop a multi-particle tracking code to simulate the instability. The results of simulation and measurement are compared and discussed. We conclude that the doubling of beam current will not onset the microwave instability even without a Landau cavity to lengthen the bunch.
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* M.H. Wang, et al.,"Longitudinal Beam Instability Observation with streak Camera at SRRC", proceeding of 1996 European Particle Accelerator Conference, pp. 1120** K. Oide, "Longitudinal Single-Bunch Instability in Electron Storage Rings", KEK Preprint 90-10 |
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WEPLT123 | Engineering Design of High-current 81.36 MHz RFQ with Elliptic Coupling Windows | sextupole, antiproton, resonance, target | 2140 | ||||||
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Four-vane RFQ structure with elliptic coupling windows has been originally developed at ITEP for injection into ITEP-TWAC synchrotron/storage ring complex, being lately adapted for RIA project too. As the electrodynamics simulations show, this structure combines the high efficiency with the operating mode stability against asymmetric detuning and electrode misalignment. A considerable reduction of structure diameter due to coupling windows becomes important for low frequency range which is necessary for the heavy ion acceleration. At the same time, the electrode configuration allows the efficient cooling and high duty factor operation. A mechanical design of 81 MHz, 1.6 MeV/u, 6 m long heavy ion RFQ section is discussed. The outer tank is made of two layers, steel and copper, joined by using the thermal diffusion technology. Each electrode is supplied with the alignment mechanism and connected to the tank by the flexible conducting insert. The whole setup is in manufacturing now.
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WEPLT126 | Beam Dynamics Simulation in High Energy Electron Cooler | sextupole, antiproton, resonance, electron | 2143 | ||||||
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The article deals with electron beam dynamics in projected high energy electron cooler. Classical electrostatic scheme with several MeV electron energy is considered. The increase of transversal energy of electrons in an accelerating section, in bends and at the matching point of magnetic fields is calculated. In order to calculate beam behavior in bends with electrostatic compensation of centripetal drift new ELEC3D electro- and magnitostatic 3D code is developed. BEAM code is used for simulation of dynamics in an accelerating section. The methods of keeping low transversal energy are estimated.
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WEPLT128 | Charge Particle Source for Industrial and Research Accelerators Operating at the Poor Vacuum Conditions | sextupole, antiproton, resonance, electron | 2146 | ||||||
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We investigated the original method of fabrication of the great number of emitting tips by pulling liquid metal through the holes in track membrane under influence of electric field. The track membranes are produced by cyclotron of Physicotechnical Institute. This method enables to fabricate up to 1·108 emitting tips per square cm. Special test facility to investigate emitter parameters operating at different values of background residual gas pressure was designed and developed. The liquid metal multiple tip field emitters possess some unique characteristics which are attractive in accelerators for material irradiation: unlimited life expectancy, large current densities (about 100 mA per sq. cm), practically unlimited surface, stable emission in poor vacuum.
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WEPLT133 | On Beam Dynamics Optimization | sextupole, antiproton, resonance, electron | 2149 | ||||||
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Mathematical optimization methods are widely used in designing and construction of charged particle accelerators. In this paper new approach to beam dynamics optimization is considered. Suggested approach to the problem is based on the analytical representation for variation of examined functionals via solutions of special partial differentional equations. The problem of optimization is considered as a problem of mutual optimization chosen synchronous particle motion and charged particles beam at whole. This approach was applied to the beam dynamics optimization for RFQ structures.
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THOBCH01 | The Beijing Electron-positron Collider and its Second Phase Construction | collider, synchrotron, injection, wakefield | 230 | ||||||
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The Beijing Electron-Positron Collider (BEPC) was constructed for both high energy physics and synchrotron radiation researches. As an e+e- collider operating in the tau-charm region and a first synchrotron radiation source in China, the machine has been well operated for 14 years since it was put into operation in 1989. As a collider, the peak luminosity of the BEPC has reached its design goal of 5*1030 cm-2s-1 at J/sai energy of 1.55 GeV and 1*1031 cm-2s-1 at 2 GeV respectively. The main parameters in the dedicated synchrotron radiation operation are: E=2.2~2.5 GeV, ex0=80 mm mrad at 2.2 GeV, Ib=140 mA and the beam lifetime of 20~30 hours. As the second phase project of the BEPC, the BEPCII , has been approved with total budget of 640 million RMB. The construction is started in the beginning of 2004 and is scheduled to complete by the end of 2007. The BEPCII is a double ring machine with its luminosity goal of 1*1033 cm-2s-1 at 1.89 GeV, two orders of magnitude higher than present BEPC. The BEPCII will operate in the beam energy of 1-2.1 GeV so that its physical potential in the whole t and charm range is preserved, while the collider will be optimized at 1.89 GeV. The upgrading of the collider should also provide an improved SR performance with higher beam energy and intensity. The beam currents will be increased to 250 mA at E=2.5 GeV for the dedicated synchrotron radiation operation of the BEPCII. Some key technologies, such as superconducting RF system, low impedance vacuum devices, superconducting micro-beta quadrupoles and etc., has been intensively studied in order to achieve the target of the BEPCII.
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THOBCH02 | DAFNE Operation with the FINUDA Experiment | synchrotron, injection, wakefield, beamloading | 233 | ||||||
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DAFNE operation restarted in September 2003, after a six months shut-down for the installation of FINUDA, a magnetic detector dedicated to the study of hypernuclear Physics. FINUDA is the third experiment running, in sequence, at DAFNE and operates while keeping on place the other detector KLOE. During the shut-down both the Interaction Regions have been equipped with remotely controlled rotating quadrupoles in order to operate at different solenoid fields. Among many other hardware upgrades one of the most significant is the reshaping of the wiggler pole profile to improve the field quality and the machine dynamic aperture. Commissioning of the collider in the new configuration has been completed in short time. The peak luminosity delivered to FINUDA has reached 6 1031 s-1 cm-2, with a daily integrated value exceeding 3 pb-1.
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Work presented by C. Milardi on behalf of the DAFNE Team |
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THOBCH03 | Barrier RF Systems in Synchrotrons | synchrotron, injection, wakefield, beamloading | 236 | ||||||
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Recently, the barrier bucket techniques have been used in many interesting applications in proton synchrotrons around the world. Specially designed broad-band rf cavities are used to generate barrier buckets. At Fermilab we have barrier RF systems in four different rings and have used them for various beam gymnastics. Particularly, in the case of Fermilab Recycler Ring, all rf manipulations required during beam cooling, beam stacking and unstacking are carried out using barrier buckets. Also, we have explored new methods for increasing the beam intensities in the Main Injector. Here, I review various uses of barrier rf system in particle accelerators and possible new applications.
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THZCH01 | Status of Tevatron Collider Run II and Novel Technologies for the Tevatron Luminosity Upgrades | synchrotron, injection, wakefield, beamloading | 239 | ||||||
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In the Tevatron Run-II, 36 antiproton bunches collide with 36 proton bunches at the CDF and D0 interaction regions at 980 GeV per beam. We present current status and performance of the collider complex. The plan for Run-II luminosity upgrades will be presented and novel technologies for the upgrade will be discussed.
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THZCH02 | Electron Cooling: Remembering and Reflecting | synchrotron, injection, electron, wakefield | 244 | ||||||
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The report contains a brief review of developments in electron cooling methods. The influence of electron cooling concepts on progress in particle beam physics is considered, particularly: development of alternative and complementary cooling methods - stochastic, laser, muon cooling; physics of cooled and intense particle beams; ordering effects in cooled ion beams and the idea of crystalline beams; intrabeam scattering in cooled beams, etc. Creation of new accelerator technology, based on electron cooling and its application to different fields of experimental physics, particle, nuclear and atomic physics, is described. Modern trends and new concepts of electron cooling applications are discussed.
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THZCH03 | JACoW, a Collaboration Serving the Accelerator Community | synchrotron, injection, electron, wakefield | 249 | ||||||
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The Joint Accelerator Conferences Website started from an idea to publish the conference proceedings on the WWW and has grown to an international collaboration which does much more than just publish the proceedings and is currently supported by seven conference series. Through attendance at Steering Committee meetings and Team Meetings and through active participation in the work of the editorial teams of sister conferences, people with the responsibility for the production of the electronic versions of conference proceedings come together to learn from the experience of colleagues, and to develop common approaches to problems. The activities of the collaboration cover all aspects of electronic publication and have recently extended into conference scientific programme management. This paper reviews the history of the collaboration, describes some of the highlights in the activities during the life of the collaboration and presents the current status and future plans.
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THYLH01 | Beam Diagnostics at the VUV-FEL Facility | electron, injection, undulator, wakefield | 262 | ||||||
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The free electron laser (FEL) at the TESLA Test facility at DESY will be the first FEL user facility for VUV and soft X-ray radiation down to 6 nm wavelength, the commissioning starts in summer 2004. Commissioning as well as stable FEL operation require a combination of different diagnostic tools for measuring both electron and photon beam parameters, including the full phase space distribution of the bunch charge, exact timing with sub-picosecond resolution, electron and photon beam overlap along the undulator, radiation beam position in the user area 50-70 m behind the undulator, intensity and spectral distribution of the radiation pulses and others. Much effort has been put in the development of instrumentation for measuring the longitudinal bunch charge distribution, for controlling the electron beam orbit along the undulator, and for online monitoring the radiation intensity, position and spectral distribution. This contribution gives an overview of the complete electron and photon beam diagnostics of the FEL facility and focuses particularly on the instrumentation which is crucial or specific for the FEL operation.
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THOBLH01 | Recent Improvement of Slow-extraction at HIMAC Synchrotron | electron, extraction, injection, undulator | 267 | ||||||
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At HIMAC synchrotron, two kinds of slow-extraction method have been developed and utilized: third-order resonant slow-extraction and that with RF-knockout, not only for ion therapy but also for physics and biological experiments. Thus, the improvements of the extracted beam quality have also been carried out in both methods. One of the improvements is the global spill control. The global spill is improved owing to analytical approach in both methods. Cooperating with the feedback system, the flat spill is easily obtained without gain control of the feedback during the extraction. On the other hand, the effect of longitudinal motion for the bunched beam was studied to suppress the frequency component of the synchrotron oscillation in the spill ripple. Further, the transport of the extracted beam is readjusted for controlling the beam size. In this paper, recent improvement of slow-extraction at HIMAC is presented.
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THOBLH02 | Ultrafast Compton Scattering X-Ray Source Development at LLNL | extraction, injection, undulator, wakefield | 270 | ||||||
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The LLNL PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility is now operating between 30 and 80 keV, and produces > 5 x 106 photons per shot at 10 Hz. This important milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as NIF diagnostics, time-resolved material studies, and advanced biomedical imaging. Initial x-rays were captured with a CCD using a CsI scintillator; the photon energy was measured at approximately 70 keV, and the observed spectral and angular distributions found to agree very well with three-dimensional codes. The electron beam was focused to 30 um rms, at 54 MeV, with 250 pC of charge, a relative energy spread of 0.2%, and a normalized emittance of 10 mm.mrad. Optimization of the x-ray dose is currently underway, with the goal of reaching 107 photons per shot and a peak brightness approaching 1017 photons/mm2/mrad2/s/0.1%bandwidth. High-Z K-edge radiographs have been demonstrated, as well as diffraction using highly-ordered pyrolytic graphite crystals. Nonlinear scattering experiments, using a tightly focused laser spot will also be discussed, as well as plans to develop a source capable of reaching 1% conversion efficiency from the electron beam kinetic energy into x-rays, and ultrafast diffraction experiments.
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THPKF026 | An Update on the SESAME Light Source | booster, beamloading, beamlosses, impedance | 2320 | ||||||
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During the past three years, the SESAME machine design has been optimised gradually taking into consideration the users demand in the Middle East region. The earlier design concept was to upgrade BESSY I to an energy of 1GeV, now SESAME is a 2.5GeV 3rd generation light source. A recent design review has recommended changing the machine lattice and layout to give greater flexibility for future upgrading and modification, the longest possible beam lines and the longest possible insertion devices, all of that with the limitation of the space available for the machine within the building. By shifting the machine by 6m from the centre of the building (in one direction) it was possible to increase the circumference of the storage ring by 3.6m into 128.4m and beam lines with lengths of 37.7m achieved, while the longest beam line in the old design was only 33.1m, this also increased the total length of the beam lines from 378.2m in the old design into 391.0m. An outline of these optimisations with their influence on the machine output is presented here. Furthermore the beam dynamics, the design of the main components of the storage ring and the first set of beam lines will be discussed.
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THPKF029 | Femto-second Electron Beam Slicing Project at SOLEIL | beamloading, damping, beamlosses, impedance | 2329 | ||||||
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The goal of the slicing project at SOLEIL is to provide short (50-100 fs) soft and hard X-rays pulses. The principle is based on the technique demonstrated earlier at ALS. In our case, the naturally suitable phase advances and the horizontal distributed dispersion enable the sliced pulse to be used on several consecutive straight sections. Further separation between the core and the sliced electron beams is obtained by increasing the effective horizontal dispersion using a chicane bracketing the modulator. In the hard X-rays case, the photon beams are separated spatially using a simple slit in a pinhole-camera type configuration while a mixed spatial-angular separation is chosen for the soft X-rays case. This minimizes the amount of parasitic core radiation scattered from the surface of the first focusing mirror. We will first describe the proposed scheme, the impact on the machine and some other issues. Then, photon optics calculation is presented. This takes into account the SOLEIL magnet lattice, realistic parameters of a femto-second laser, peculiarities of spectral distributions of undulator radiation and its diffraction in the range of intensities covering several orders of magnitude.
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THPKF038 | Radiation Damage of Magnet Coils due to Synchrotron Radiation | target, booster, beamloading, beamlosses | 2356 | ||||||
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Radiation damage of the equipment in the SPring-8 storage ring tunnel has become a serious problem. In the storage ring, the unnecessary radiation from bending magnets is shielded by absorbers. The equipment around the absorbers was damaged by the scattered radiation from the absorbers. Last year, cooling water leaked from the rubber hose of magnets. It was due to the deterioration of rubber hose caused by synchrotron radiation. We measured the radiation distribution around the storage ring and found that the most high intensity spot was on the magnet coil near the absorbers. If the coils are damaged and the magnets do not work correctly, we need to shut down the storage ring to exchange the magnet coils. To avoid such a situation, we needed to clarify the relation between the radiation damage of the coils and the dose of radiation. We did an acceleration test of the radiation damage of magnet coils. The magnet coils were exposed to the radiation from the bending magnet directly. We observed the degree of damage with changing the doses of radiation. In this paper, we describe about these acceleration tests and test results.
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THPKF039 | Study of Photo-cathode RF Gun for a High Brightness Electron Beam | target, cathode, booster, beamloading | 2359 | ||||||
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We are going to develop a compact high-brightness electron beam system to adopt industrial and medical applications. A multi-bunch photo-cathode RF gun has been developed to generate 100 bunches beam with 2.8ns spacing and 5nC charge per bunch. We will report details of the development, especially photo-cathode production and emission characteristics from cathode by the laser.
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THPKF061 | RT-office for Electron Beam, X-ray, and Gamma-ray Dosimetry | target, gun, beamlosses, laser | 2400 | ||||||
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An absorbed dose of electron beam (EB),X-ray (bremsstrahlung), and gamma-ray within the irradiated product is one of the most important characteristic for all industrial radiation-technological processes. The conception for design of the Radiation-Technological Office (RT-Office) - software tools for EB, X-ray, and gamma-ray dosimetry for industrial radiation technologies was developed by authors. RT-Office realize computer technologies at all basic stages of works execution on the RTL using irradiators of EB, X-ray, and gamma-ray in the energy range from 0.1 to 25 MeV. The specialized programs for simulation of EB, X-ray, and gamma-ray processing and for decision of special tasks in dosimetry of various radiation technologies were designed on basis of the RT-Office modules. The use of the developed programs as predictive tools for EB,X-ray, and gamma-ray dose mapping, for optimization of regimes irradiation to receive minimum for dose uniformity ratio, for reducing the volume of routine dosimetry measurements of an absorbed dose within materials at realization of the radiation-technological processes are discussed in the paper.
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THPKF075 | LUX - A Recirculating Linac-based Facility for Ultrafast X-ray Science | electron, linac, coupling, simulation | 2436 | ||||||
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We present design concepts for LUX - a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac. The source produces high-flux VUV-x-ray pulses with duration of 100 fs or less at a 10 kHz repetition rate, optimized for the study of ultra-fast dynamics across many fields of science. Cascaded harmonic generation in free-electron lasers (FEL's) produces coherent radiation in the VUV-soft x-ray regime, and a specialized technique is used to compress spontaneous emission for ultra-short-pulse photon production in the 1 - 10 keV range. High-brightness electron bunches of 2-3 mm-mrad emittance at 1 nC charge in 30 ps duration are produced in an rf photocathode gun and compressed to 3 ps duration following an injector linac, and recirculated three times through a 1 GeV main linac. In each return path, harmonic cascades are inserted to produce seeded FEL radiation in selected photon energy ranges from approximately 20 eV with a single stage of harmonic generation, to 1 keV with a four-stage cascade. The lattice is designed to minimize emittance growth from effects such as coherent synchrotron radiation (CSR), and to propagate electron beams carrying nm-scale density modulation in the final stages of cascaded harmonic generation. Synchronization of tens of femtoseconds is achieved by use of an optical master oscillator distributing timing signals over actively stabilized fiber, and generation of rf signals from the optical master oscillator. We describe technical developments in key areas including injection from a high repetition rate rf photocathode gun, lattice design, UV and soft x-ray production by high-gain harmonic generation, a kicker design for rapid transfer of the electron beam between radiator beamlines, lasers systems concepts, and synchronization between experimental pump lasers and the x-ray pulse.
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THPKF076 | Plan to Upgrade the Advanced Light Source to Top-off Injection Operation | electron, linac, simulation, insertion | 2439 | ||||||
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The brightness and thermal stability of the Advanced Light Source (ALS) is lifetime limited. Brightness improvements such as narrower gap insertion devices, smaller emittance coupling, and higher currents all result in short lifetimes. In addition current changes over a fill impact the thermal stability of both the storage ring and beamlines. In order to mitigate these limitations there is a plan to upgrade the injector of the ALS to full energy injection and to operate in a quasi-continuous filling (Top-Off) injection operation. With Top-Off, the ALS will increase its time-averaged current by two, reduce the vertical emmittance, and operate with smaller gap insertion devices. In this paper we describe our upgrade plan.
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THPKF077 | A Fiber Optic Synchronization System for LUX | linac, laser, simulation, insertion | 2442 | ||||||
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The proposed LUX femtotsecond light source will support pump-probe experiments that will need to synchronize laser light pulses with electron-beam-generated X-ray pulses to less than 50fs at the experimenter endstations. To synchronize multiple endstation lasers with the X-ray pulse, we are developing a fiber-distributed optical timing network. A high stability clock signal from a modelocked laser is distributed via fiber to RF cavities (controlling X-ray probe pulse timing) and modelocked lasers at endstations (controlling pump pulse timing). The superconducting cavities are actively locked to the optical clock phase. Most of the RF timing error is contained within a 10kHz bandwidth, so these errors and any others affecting X-ray pulse timing (such as RF gun phase) can be detected and transmitted digitally to correct laser timing at the endstations. The lasers? timing jitter is limited to low frequency, and thus they will follow the controls (clock plus error correction) without adding much wideband error. Time delay through the fibers will be stabilized by comparing a retroreflected pulse from the experimenter endstation end with a reference pulse from the sending end, and actively controlling the fiber length. Numerical simulations and initial synchronization experimental results will be presented.
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THPKF084 | Emerging Concepts, Technologies and Opportunities for Mezzo-scale Terahertz and Infrared Facilities | electron, linac, laser, simulation | 2451 | ||||||
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Recent advances in particle beam, laser and radiofrequency technologies, combined with innovative concepts and techniques such as energy recovery, coherent synchrotron radiation-induced bunching, laser-particle beam scattering, ultrashort pulse slicing, cw high current and brightness phtoinjectors, ultrafast laser switching and compact engineered end products have opened up new opportunities and vistas in terahertz/infrared radiation sources not available before. Such sources would complement the high energy short wavelength x-ray sources in that they will allow us to probe collective processes and their ?function? in complex systems and materials, in a fashion complementary to probing structure via x-rays. We will outline and give examples of both the scientific reach of such radiation sources as well as examples of a few conceived facilities and techniques worldwide spanning a diversity of spectral, coherence, brightness and application ranges in the long wavelength. Such facilities fall in the category of mezzo-scale facilities, bracketed by table top lasers on one hand and large scale synchrotron radiation sources on the other and offer very unique and directed advances in a few key areas in life, materials, imaging, instrumentation and communication sciences.
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THPKF088 | NSLS II: A Future Source for the NSLS | linac, laser, simulation, insertion | 2454 | ||||||
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The National Synchrotron Light Source at BNL was the first dedicated light source facility and has now operated for more than 20 years. During this time, the user community has grown to more than 2400 users annually. To insure that this vibrant user community has access to the highest quality photon beams, the NSLS is pursuing the design of a new ultrahigh brightness (~ 1E21) electron storage ring, tailored to the 0.3-20 keV photon energy range. We present our preliminary design and review the critical accelerator physics design issues.
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THPLT003 | Vibrating Wire Scanner Parameters Optimization | linac, laser, simulation, insertion | 2457 | ||||||
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The idea to use the metallic vibrating wire as a scanner of particles beams was experimentally confirmed [1, 2] and showed unprecedented sensibility and a huge dynamic rage of the output signal. In this work the response time of the system is estimated on the base of the dynamic model of heat transfer through the wire. A comparison of different materials of the wire is presented and the most suitable materials for different tasks are suggested. The dielectric materials are considered as possible materials of the wire, use of which allows to eliminate the electromagnetic induction from high current beams during the scanning of beam halo. The results of scanning of the iron ion beam of the mass spectrometer are presented. 1. Arutunian S.G., Avetisyan A.E., Dobrovolski N.M., Mailian M.R., Vasiniuk I.E, Wittenburg K., Reetz R., Problems of Installation of Vibrating Wire Scanners into Accelerator Vacuum Chamber. - Proc. 8-th Europ. Part. Accel. Conf. (3-7 June 2002, Paris, France), pp. 1837-1839. 2. Arutunian S.G., Dobrovolski N.M., Mailian M.R., Vasiniuk I.E., Vibrating wire scanner: first experimental results on the injector beam of Yerevan synchrotron.- Phys. Rev. Special Topics. - Accelerators and Beams, 2003, v. 6, 042801.
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THPLT044 | Measurement of the Transverse Coherence of the TTF Free Electron Laser | antiproton, undulator, positron, synchrotron | 2577 | ||||||
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The transverse coherence is important for many applications of a free electron laser (FEL). It depends on the inner structure of the electron bunch in the undulator, which is difficult to measure. It is therefore essential to determine the coherence properties of the FEL radiation directly. The coherence of the vacuum ultraviolet FEL at the TESLA Test Facility has been measured by recording the diffraction pattern of a double slit and measuring the visibility of the interference fringes. The experimental near field diffraction pattern is compared with a numerical model, taking into account the formation of the FEL radiation, the Fresnel diffraction in the near field zone and effects of the experimental set-up. Diffraction patterns have been recorded at various undulator lengths to measure the evolution of the transverse coherence along the undulator. This is compared to the expected evolution of the transverse radiation modes.
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THPLT045 | A more Accurate Approach to Calculating Proton Bunch Evolution under Influence of Intra-beam Scattering in a Storage Ring. | antiproton, undulator, positron, synchrotron | 2580 | ||||||
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Some perturbations of discrete nature are known to influence the performance of a proton storage ring, contributing to parasitic background, decay of beam currents and bunch tail buildup. Such are, for example, intra-beam scattering and residual gas scattering .These processes are to a big extent described by existing analytical theory. The latter, employing a large amount of averaging, usually neglects effects arising from system nonlinearity. So, the motion of tail particles in the presence of a sufficiently nonlinear RF voltage under influence of intra-beam scattering strongly deviates from the average across the bunch and the analytical approach seems inadequate for it. To overcome this situation we have developed more accurate numerical methods for calculations of bunch evolution under influence of a rather broad class of jump-like perturbations. Here we present the computational algorithms and their application to assessment of coasting beam and proton background in HERA-p.
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THPLT046 | The Synchrotron Radiation Beamline at TTF2 | antiproton, positron, scattering, simulation | 2583 | ||||||
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The VUV-FEL at DESY, Hamburg, will require novel techniques to characterize the longitudinal charge distribution of the electron bunches that drive the free-electron laser. Conventional methods are inadequate at the short bunch lengths that will be obtained. One technique under study uses coherent far-infrared radiation to reconstruct the bunch shape through Fourier analysis of the spectrum. In a first step, a beam line to guide both far-infrared (50-1000 um) and optical synchrotron radiation from one of the bunch compressor magnets of the linear accelerator to a diagnostic station outside of the controlled area is currently under construction. It will also allow a comparison between streak camera and far-infrared measurements for features on length scales above some 100 um (the streak camera resolution). Later, infrared techniques extending to shorter wavelengths, i.e. to shorter bunch lengths, will also be used further downstream the accelerator, employing synchrotron, transition and undulator radiation. The beam line design, measurement principle and first measurements will be presented.
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THPLT047 | Beam Position Monitor Development for the IThemba LABS Cyclotron Beamlines | antiproton, positron, scattering, simulation | 2586 | ||||||
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In cooperation of iThemba LABS (South Africa) and Forschungszentrum Juelich the specification of a sensitive tunable rf narrowband beam position monitor system for cyclotron beamlines has been elaborated. iThemba LABS developed and manufactured the four section stripline monitor chamber. The monitor electronics were developed in the Forschungszentrum Juelich-IKP. The electronics consisting of an RF signal processing module (BPM-RF) and a data acquisition and control module (BPM-DAQ) sequentially processes and measures the monitor signals and deliver via serial network calculated horizontal and vertical beam position data. First measurements with cyclotron beam has been performed in the iThemba LABS in November 2003. Changed beam position due to changing different cyclotron parameters could be studied with high accuracy. The resolution of the beam position measurement was better than 0.1 mm with beam currents down to 0.0005 mA.
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THPLT048 | Progress in 3D Space-charge Calculations in the GPT Code | antiproton, positron, scattering, simulation | 2589 | ||||||
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The mesh-based 3D space-charge routine in the GPT (General Particle Tracer, Pulsar Physics) code scales linearly with the number of particles in terms of CPU time and allows a million particles to be tracked on a normal PC. The crucial ingredient of the routine is a non-equidistant multi-grid Poisson solver to calculate the electrostatic potential in the rest frame of the bunch. The solver has been optimized for very high and very low aspect ratio bunches present in state-of-the-art high-brightness electron accelerators. In this paper, we explore the efficiency and accuracy of the calculations as function of meshing strategy and boundary conditions.
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THPLT050 | End to End Simulations of the RX2 Beam Transport | antiproton, positron, scattering, simulation | 2592 | ||||||
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RX2 is a project aiming to produce a high flux of X-rays for radiography purpose. We proposed an RF linac using a DC photo-injector producing 20 bunches with 100nC each at 352 MHz. The beam is then injected in 4 RF superconducting cavities and accelerated to 40 MeV. It is then focused on a target producing X-rays. Here is presented the design, the specificities, and the beam simulations from the cathode to the target by coupling 2 multiparticle codes : PARMELA and PARTRAN.
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THPLT051 | End to End Multiparticle Simulations of the AIRIX Linac | antiproton, positron, scattering, simulation | 2595 | ||||||
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AIRIX is a working 3 kA, 20 MeV induction accelerator. It has been designed with an enveloppe code : ENV. A new set of multiparticle codes (PBGUNS, MAGIC, PARMELA and PARTRAN) has been used recently to simulate the beam transport with an higher accuracy especially taking into account the field non-linearities. A dedicated space-charge routine has been written. The calculation results have been compared to experimental measurements.
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THPLT052 | Measurement of Relative Gas Chamber Pressure in Narrow Straight Section Vacuum Vessels by Observing Gas Bremstrahlung | vacuum, antiproton, positron, scattering | 2598 | ||||||
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The measurement of gas pressure inside long, small cross section, vacuum vessels is difficult due to the distance between the centre of the vacuum vessel and vacuum gauges (leading to a low vacuum conductance). Following initial chamber installation, significant out-gassing is observed leading to a significant pressure bump within the chamber. A modified beam loss detector has been developed in order to monitor the gamma radiation produced by the collision of the 6GeV electrons in the storage ring with residual gas atoms. The narrow beam of gamma radiation is intercepted at various points by high Z materials in the beam line front-end allowing a radiation shower to be detected outside the vacuum vessel proportional to the gas pressure in the corresponding storage ring straight section. Various locations are considerred and results shown.
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THPLT053 | Fast Orbit Feedback Developments at ELETTRA | vacuum, antiproton, feedback, positron | 2601 | ||||||
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A number of fast local orbit feedback stations are being sequentially installed at ELETTRA to improve the stability of the electron beam at the Insertion Device source points. They rely on Beam Position Monitors equipped with digital detector electronics that provides high precision and readout rate. The local feedback stations will be integrated in a fast global orbit feedback system, which is the goal of the ongoing developments. The performance and the operational experience gained with the local feedback systems are presented together with the planned road map towards the global system.
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THPLT054 | Emittance Diluition due to 3D Perturbations in RF Photoinjectors. | vacuum, antiproton, feedback, positron | 2604 | ||||||
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The predictions from different simulation codes are compared to investigate the effects of non axis-symmetric conditions, fluctuations in cathode's quantum efficiency and other sources of dishomogeneities in the performances of a typical RF photoinjector. The layout includes a RF gun and a focusing solenoid in a configuration aimed at minimizing the emittance growth due to space charge effects.
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THPLT055 | Longitudinal Phase Space Characterization of the CTF3 Beam with the RF Deflector | vacuum, antiproton, feedback, positron | 2607 | ||||||
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The characterization of the longitudinal phase space of the CTF3 beam is an important item for tuning all machine parameters and increase the 30 GHz power production. By means of an RF deflector and a dispersive system the longitudinal phase space can be completely characterized. In this paper we present the simulation of the measurement and the mechanical layout of the full system.
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THPLT056 | Horizontal Instability and Feedback Performance in DAFNE e+ Ring | vacuum, antiproton, feedback, scattering | 2610 | ||||||
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In DAFNE, after the 2003 shutdown for the installation of FINUDA, a strong horizontal multibunch instability was found to limit the positron beam current at the level of ~450 mA. We have performed transverse grow-damp measurements in order to estimate the instability growth rates as well as the feedback damping rates for each bunch at different beam currents and to evaluate the tune shift along the bunch train. In particular, a strong dependence of oscillation amplitudes on the relative position of the bunch in the train has been observed. In this paper we describe the setup for multibunch oscillation amplitude recording, discuss the transverse feedback performance and summarize some observations on the transverse instability. The feedback rises the threshold by about a factor of two, depending on the machine configuration.
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THPLT057 | An RF Deflector Design for 6d Phase Space Characterization of the Sparc Beam | vacuum, antiproton, feedback, scattering | 2613 | ||||||
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The characterization of the longitudinal and transverse phase space of the beam provided by the SPARC photoinjector is a crucial point to establish the performance quality of the photoinjector itself. By means of an RF deflector and a dispersive system, the six dimensional beam phase space can be analyzed. A five cell SW aluminum prototype of the SPARC RF deflector has been realized and tested. We report in this paper the design issues together with the RF measurement results. The simulation results of the 6D phase space reconstruction of the SPARC beam are also presented.
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