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MOPCH005 | The ARC-EN-CIEL FEL Proposal | laser, radiation, undulator, FEL | 53 | ||||
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ARC-EN-CIEL (Accelerator-Radiation Complex for Enhanced Coherent Intense Extended Light), the French project of a fourth generation light source aims at providing the user community with coherent femtosecond light pulses covering from UV to soft X ray. It is based on a CW 1 GeV superconducting linear accelerator delivering high charge, subpicosecond, low emittance electron bunches with a high repetition rate (1 kHz). Electron beam calculations will be presented. The FEL is based on the injection of High Harmonics Generated in Gases (HHG) in a High Gain Harmonic Generation scheme, leading to a rather compact solution. The produced radiation extending down to 0.8 nm with the Non Linear Harmonics reproduces the good longitudinal and transverse coherence of the harmonics in gas. Calculations are preformed with PERSEO, taking into account the proper transverse overlap between HHG and the electron beam, and with SRW. Optional beam loops are foreseen to increase the beam current or the energy. They will accommodate fs synchrotron infrared Coherent Synchrotron Radiation sources, VUV and X ray ranges and a FEL oscillator in the 10 nm range. An important synergy is expected between accelerat
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MOPCH013 | Slice Emittance Measurements at FLASH | quadrupole, DESY, RF-structure, CSR | 77 | ||||
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The SASE process in Free Electron Lasers mainly depends on time-sliced parameters of charge density, energy spread and transverse emittance. At the VUV-FEL at DESY, electron bunches are compressed longitudinally in two magnetic chicanes in order to achieve high peak currents. The compression causes considerabe variations in slice emittance along the bunches. The vertically deflecting rf-structure LOLA, which is in operation at the VUV-FEL since early 2005, allows to resolve longitudinal variations in horizontal slice width for single bunches. The horizontal slice emittances can be determined by additionally varying the strengths of the quadrupoles upstream of LOLA. Results of slice emittance measurements using different bunch compression schemes are presented.
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MOPCH014 | Energy-time Correlation Measurements Using a Vertically Deflecting RF Structure | acceleration, CSR, FEL, DESY | 80 | ||||
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To initiate the lasing process in SASE-based Free Electron Lasers, electron bunches with high peak currents are necessary. At the VUV-FEL at DESY, high peak currents are produced by bunch shortening in magnetic chicanes induced by a linear energy-time gradient. The residual uncorrelated time-sliced energy width after compression is a crucial parameter for the lasing process. The final energy-time correlation provides important information about the compression process. This paper presents a measurement of slice energy spread and energy-time correlation using a vertically deflecting rf-structure (LOLA). The structure allows to map the time delay of bunch slices to the vertical axis of a screen. After dispersing the bunches horizontally with a dipole, the energy-time correlation can be directly obtained in a single shot measurement. Results for different bunch compression schemes are presented. The measured bunch length in case of a non-compressed beam is compared to streak camera measurements.
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MOPCH028 | Status of the SPARX FEL Project | linac, simulation, undulator, brightness | 107 | ||||
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The SPARX project consists in an X-ray-FEL facility jointly supported by MIUR (Research Department of Italian Government), Regione Lazio, CNR, ENEA, INFN and Rome University Tor Vergata. It is the natural extension of the ongoing activities of the SPARC collaboration. The aim is the generation of electron beams characterized by ultra-high peak brightness at the energy of 1 and 2 GeV, for the first and the second phase respectively. The beam is expected to drive a single pass FEL experiment in the range of 13.5-6 nm and 6-1.5 nm, at 1 GeV and 2 GeV respectively, both in SASE and SEEDED FEL configurations. A hybrid scheme of RF and magnetic compression will be adopted, based on the expertise achieved at the SPARC high brightness photoinjector presently under commissioning at Frascati INFN-LNF Laboratories. The use of superconducting and exotic undulator sections will be also exploited. In this paper we report the progress of the collaboration together with start to end simulation results based on a combined scheme of RF compression techniques.
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MOPCH029 | Status of the SPARC Project | laser, gun, undulator, electron | 110 | ||||
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The SPARC Project is starting the commissioning of its photo-injector. RF gun, RF sources, RF network and control, power supplies, emittance meter, beam diagnostics and control to measure the RF gun beam are installed. The photocathode drive laser has been characterized in terms of pulse shape and quality. We expect to conduct beam measurements at RF gun exit in the next future and consequently to start the installation of accelerating sections. The design of the 12 m undulator for the FEL experiment has been completed and the first undulator section out of 6 is under construction: we expect to characterize it at Frascati ENEA laboratory within the next months. SPARC as a facility will host FEL experiments using SASE, seeding and non-linear resonant harmonics. Additional R&D on X-band and S-band structures for velocity bunching are in progress, as well as studies on new photocathode materials and exotic undulator designs. We also present studies on solenoid field defects, beam based alignments, exotic electron bunch production (blow-out of short laser pulses or intensity modulated laser pulses). The possible use of segmented superconducting micro-undulators will be discussed too.
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MOPCH030 | Production of Coherent X-rays with a Free Electron Laser Based on an Optical Wiggler | laser, radiation, electron, FEL | 113 | ||||
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The interaction between high-brightness electron beams and counter-propagating laser pulses produces X rays via Thomson scattering. If the laser source is long enough, the electrons bunch on the scale of the emitted X-ray wavelength and a regime of collective effects establishes. In this case, the FEL instability develops and the system behaves like a FEL based on an optical undulator. Coherent X-rays are irradiated, with a bandwidth thinner than that of the incoherent emission. The emittance of the beam and gradients or irregularities in the laser energy distribution are the principal factors that limit the growth of the X-ray signal. We analyse with a 3-D code the transverse effects in the emission produced by a relativistic electron beam when it is under the action of an optical laser pulse and the X-ray spectra obtained. The scalings typical of the optical wiggler, with very short gain lengths and overall time durations of the process make possible considerable emission also in violation of the Pellegrini criterion for static wigglers. A generalized form of this criterion is validated on the basis of the numerical evidence.
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MOPCH031 | Progress on the Pi-mode X-band RF Cavity for SPARC | simulation, vacuum, radiation | 116 | ||||
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The Frascati photo-injector SPARC (Pulsed Self Amplified Coherent Radiation Source) will be equipped with an x-band RF cavity for linearizing emittance to enhance bunch compression and for reducing bunch longitudinal energy spread. The nine cell standing wave cavity prototype made of separated cells has been already built and measured*. In this paper we report on characterization of the first brazed prototype. Heat load studies have been performed as well to design the cooling system for the final device.
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*D. Alesini et al. Nucl. Instr. and Meth. A 554 (2005) 1. |
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MOPCH036 | Photocathode Roughness Impact on Photogun Beam Characteristics | cathode, electron, gun, FEL | 121 | ||||
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Photocathode surface roughness has an impact on photoelectron yield, bunch duration, beam emittance at the exit of femtosecond photogun with an accelerating field that is considered in assumption of quasi-stationary one in the paper. The main problem in investigating the impact is determination of the field near the surface, statistical properties of which are defined through rms values of deviation and slope in profile line of the surface roughness. Developed and created code allows determining the field with relative rms error not worse than 0.001%. The results of the investigation for rms values of roughness and its slope within respectively 500
0 nm and 20
0 degrees are presented and discussed.
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MOPCH041 | Design of a New Preinjector for the MAX Recirculator to be Used in EUROFEL | gun, linac, cathode, simulation | 130 | ||||
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The MAX-lab recirculator injector will be equipped with a new preinjector system. The aim is to reduce the emittance, increase the charge and achieve a proper timing between accelerator and laser systems. All is aimed at the MAX-lab test facility for HG built in collaboration with BESSY in the EUROFEL program. The preinjector system consists of a photo cathode RF-gun with an emittance compensating solenoid. Special issues regard the injection of the new beam into the beam path of the MAX recirculator and the conservation of beam parameters.
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MOPCH042 | Progress in the Design of a Two-Frequency RF Cavity for an Ultra-Low Emittance Pre-Accelerated Beam | injection, electron, cathode, coupling | 133 | ||||
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Today most of the X-rays Free-Electron Laser projects are based on state of the art RF guns, which aim at a normalized electron beam emittance close to 1 mm$·$mrad. In this paper we report on the progress made at PSI towards a hybrid DC + RF Low Emittance Gun (LEG) capable of producing a beam with an emittance below 0.1 mm.mrad. To reduce the intrinsic thermal emittance at the LEG cathode the electrons are extracted from nano-structured field-emitters. A gun test facility is under construction wherein after emission the beam is accelerated up to 500 keV in a diode before being injected and accelerated in a two-frequency 1.5-cell RF cavity. The fast acceleration in the diode configuration allows to minimize the emittance dilution due to the strong space charge forces. The two-frequency RF structure is optimized to limit the emittance blow-up due to the non-linearity of the RF field.
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MOPCH047 | Study of the Electron Beam Dynamics in the FERMI @ ELETTRA Linac | electron, linac, laser, simulation | 145 | ||||
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A study of the electron beam dynamics in the linac is made within the framework of the design of a free electron laser (FEL) at the Syncrotrone Trieste*. A scope of the work includes analysis of two operational scenarios, one with relatively long electron bunches of the order of 1.5 ps and a moderate peak current of 500 A and one with shorter bunches of the order of 0.7 ps and higher peak current of the order of 800 A. In both cases, care has been taken to preserve the slice and projected emittances formed in the photocathode gun injector and to minimize the slice energy spread. The latter goal is accomplished by balancing the onset of the microbunching instability driven by the longitudinal space charge forces and the emission of coherent synchrotron radiation using Landau damping produced by a so-called laser heater. Various analytical techniques and tracking codes have been employed to obtain the reported results.
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*C. Bocchetta, et al., this conference. |
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MOPCH062 | Centroid, Size, and Emittance of a Slice in a Kicked Bunch | synchrotron, radiation, betatron, photon | 172 | ||||
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A transversely kicked bunch will decohere due to, among other things, chromatic and amplitude-dependent tune shifts. The chromatic tune shift leads to correlation between transverse and longitudinal phase space. Such a correlation can be used for compressing synchrotron radiation of the bunch with adequate optics. In this report, we revise the decoherence calculation to derive the centroid and second moments of a beam slice in a kicked bunch, taking into account chromatic and nonlinear decoherence, but neglecting wakefield and radiation damping, etc. A simple formula for estimating slice bunch length (and potential pulse compression ratio) is given for the ideal situation.
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MOPCH071 | Optimization of Optics at 200 MeV KEK-ERL Test Facility for Suppression of Emittance Growth Induced by CSR | CSR, dipole, insertion, insertion-device | 190 | ||||
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Energy Recovery Linac (ERL) gets a lot of attention as a next period light source instrument. To produce high-brightness and short pulse synchrotoron lights, it is necessary to pass through high current and short bunch electron beams to the insertion part of ERL with keeping the low emittance and the low energy spread. However, it is challenging because Coherent Synchrotorn Radiation (CSR) generated at bending magnets is potential sources of the emittance growth which is enomous especially for high current, short bunch and a low energy beam. Therefore, it is benefit to a gradual bunch compression in the arc after accelerating the beam up to the full energy. The beam optics and lattice design of 200MeV ERL Test Facility is optimized to suppress the emittance growth caused by CSR at the arc section on two conditions, high-current mode (100mA, 1psec) and short bunch mode (0.1psec) similar to 5GeV ERL facility proposed by Cornell University.
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MOPCH073 | A Project of a High-power FEL Driven by an SC ERL at KAERI | FEL, sextupole, ERL, dipole | 196 | ||||
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A project of a high-power FEL at Korea Atomic Energy Research Institute is described. The FEL is driven by a superconducting energy recovery linac. The future ERL will be connected to the existing machine without any modification. It consists of two 180-degree bents and two straight sections: one is for the FEL, another for a Compton X-rays source. One can choose the regime controlling the lenses. The total ERL is isochronous to avoid any problems with longitudinal beam instability. The total relative emittance degradation through the whole machine is ? 1.5. The FEL will be based on a 2 m helical in-vacuum undulator made of permanent magnets. One mirror of the optical cavity is blind and made of copper; the other one, the outcoupler, is semi-transparent and made of CVD diamond. The expected average power is a few kW and the tuning range 35
70 ?m.
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MOPCH081 | FLAIR: a Facility for Low-energy Antiproton and Ion Research | antiproton, ion, storage-ring, CERN | 220 | ||||
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To exploit the unique possibilities that will become available at the Facility for Antiproton and Ion Research (FAIR), a collaboration of about 50 institutes from 15 countries was formed to efficiently enable an innovative research program towards low-energy antimatter-physics. In the Facility for Low-energy Antiproton and Ion Research (FLAIR) antiprotons and heavy ions are slowed down from 30 MeV to energies as low as 20 keV by a magnetic and an electrostatic storage ring. In this contribution, the facility and the research program covered are described with an emphasis on the accelerator chain and the expected particle numbers. An overview of the novel beam handling, cooling and imaging techniques as they will be required across the facility is given.
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MOPCH086 | Stochastic Cooling for the HESR at the GSI-FAIR Complex | target, antiproton, pick-up, kicker | 231 | ||||
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The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt is planned as an anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An important and challenging feature of the new facility is the combi-nation of phase space cooled beams with internal targets. The required beam parameters and intensities are prepared in two operation modes: the high luminosity mode with beam intensities up to 1011 and the high reso-lution mode with 1010 anti-protons cooled down to a relative momentum spread of only a few 10-5. In addition to electron cooling, transverse and longitudinal stochastic cooling are envisaged to accomplish these goals. It is shown how the great benefit of the stochastic cooling system to adjust the cooling force in all phase planes independently is utilized to achieve the requested beam spot and the high momentum resolution at the internal target within reasonable cooling down times for both HESR modes even in the presence of intra-beam scattering. A numerical and analytical approach to the Fokker-Planck equation for longitudinal filter cooling has been carried out.
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MOPCH094 | Low-intensity Beams for LHC Commissioning from the CERN PS-booster | LHC, injection, CERN, proton | 255 | ||||
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A variety of low-intensity beams will be required for LHC commissioning. In contrast to the nominal LHC physics beam, these single-bunch beams are produced without longitudinal bunch splitting in the injector chain. Consequently, not only the transverse but also the longitudinal beam characteristics have already to be established in the CERN PS-Booster. The required intensities extend down to four orders of magnitude below the typical PS-Booster working range and the transverse emittances must be adjustable to vary the beam brightness over a large range. The different beam variants are briefly summarized and the specific techniques developed for their production, like low-voltage rf capture, and transverse and longitudinal shaving, are described. In particular, the choice of harmonic number and its consequences for operation and beam reproducibility are discussed. Finally, the performance achieved for the different beams is summarized.
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MOPCH095 | Performance of Nominal and Ultimate LHC Beams in the CERN PS-booster | LHC, injection, optics, CERN | 258 | ||||
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The requirements for nominal and ultimate LHC beams in the CERN PS-Booster were specified in 1993 and served as input for the definition of the "PS conversion for LHC" project. Already during the upgrade project and also after its completion in 2000, the beam intensities to be provided from the PS Booster were increased in order to compensate for changes on the LHC machine, the beam production scheme in the PS and for non-anticipated beam losses along the injector chain. In order to improve the beam brightness, to be compatible with the increased requirements, extensive machine studies have taken place on the PS-Booster. The working point was changed to reduce the influence of systematic resonances and the injection line optics was re-matched to improve the injection efficiency. The paper summarizes briefly the evolution of the performance requirements. The various measures undertaken to improve the LHC beam quality are outlined and the present performance achieved in the PS-Booster is presented.
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MOPCH108 | Error Study of LINAC 4 | linac, simulation, quadrupole, CERN | 294 | ||||
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Within the framework of the Joint Research Activity HIPPI (High Intensity Pulsed Proton Injector) of the CARE program, the conception study of the LINAC 4 accelerator which aims to intensify the proton flux available for the CERN injection line is pursued. The linac, operating in pulsed mode at 352 MHz, is designed to accelerate a 65 mA beam of H- ions up to an energy of 160 MeV. The requirements on acceptable beam emittance growth and particle loss are extremely tight. In order to determine the Drift Tube Linac tolerances, we examined the sensitivity of the LINAC 4 DTL to errors on the accelerating field and the focusing quadrupoles. Simulations were performed with the transport code TRACEWIN (CEA-Saclay, France). We will present results on individual sensitivities to a single error as well as the global impact of alignment and RF errors on the beam quality. Similarly, accelerating structures following the DTL in the LINAC4 design (CCDTL, SCL) have been studied.
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MOPCH111 | A Fast Beam Chopper for the RAL Front End Test Stand | linac, CERN, proton, quadrupole | 300 | ||||
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The FETS project at RAL will test a fast beam chopper, designed to address the requirements of high power proton drivers for next generation pulsed spallation sources and neutrino factories. A description is given of the novel RAL 'Fast - Slow' chopping scheme, and of candidate optical designs for the 3.0 MeV, 60 mA, H- Medium Energy Beam Transport (MEBT) line.
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MOPCH112 | The RAL Front End Test Stand | rfq, ion-source, ion, linac | 303 | ||||
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High power proton accelerators (HPPAs) with beam powers in the megawatt range have many possible applications including drivers for spallation neutron sources, neutrino factories, waste transmuters and tritium production facilities. These applications typically propose beam powers of 5 MW or more compared to the highest beam power achieved from a pulsed proton accelerator in routine operation of 0.16 MW at ISIS. The UK's commitment to the development of the next generation of HPPAs is demonstrated by a test stand being constructed in collaboration between RAL, Imperial College London and the University of Warwick. The aim of the RAL Front End Test Stand is to demonstrate that chopped low energy beams of high quality can be produced and is intended to allow generic experiments exploring a variety of operational regimes. This paper describes the status of the RAL Front End Test Stand which consists of five main components: a 60 mA H- ion source, a low energy beam transport, a 324 MHz Radio Frequency Quadrupole accelerator, a high speed beam chopper and a comprehensive suite of diagnostics. The aim is to demonstrate production of a 60 mA, 2 ms, 50 pps, chopped H- beam at 3 MeV.
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MOPCH127 | SNS Warm Linac Commissioning Results | linac, CCL, beam-losses, SNS | 342 | ||||
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The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector, capable of producing one-ms-long pulses at 60Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5MeV beam from the Front End is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. Current results of the beam commissioning program of the warm linac will be presented including transverse emittance evolution along the linac, longitudinal bunch profile measurements at the beginning and end of the linac, and beam loss study.
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MOPCH129 | Status of the SNS Beam Power Upgrade Project | SNS, target, linac, kicker | 345 | ||||
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The baseline Spallation Neutron Source (SNS) accelerator complex, consisting of an H- injector, a 1 GeV linear accelerator, an accumulator ring and associated transport lines, will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. Upgrades to the SNS accelerator and target systems to increase the beam power to at least 2 MW, with a design goal of 3 MW, are in the planning stages. The increased SNS beam power can be achieved primarily by increasing the peak H- ion source current from 38 mA to 59 mA, installing additional superconducting cryomodules to increase the final linac beam energy to 1.3 GeV, and modifying injection and extraction hardware in the ring to handle the increased beam energy. The mercury target power handling capability will be increased to 2 MW or greater by i) mitigating cavitation damage to the target container through improved materials/surface treatments, and introducing a fine dispersion of gas bubbles in the mercury, and ii) upgrading the proton beam window, inner reflector plug and moderators. The upgrade beam parameters will be presented and the required hardware modifications will be described.
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MOPCH177 | Status of HOM Load for the Cornell ERL Injector | ERL, linac, damping, electron | 478 | ||||
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The HOM load for the injector of the Energy Recovery Linac at Cornell University is proposed to work at a temperature of 80 K. The anticipated absorbed power of the load is up to 200 W. Versions with inner diameter of 78 and 106 mm are under development. Two different kinds of ferrites and a lossy ceramic are chosen as RF absorbers for the load to cover a wide frequency range. Measurements of electromagnetic properties of absorbing materials have been performed in a frequency range from 1 to 40 GHz. The engineering design of the load is ready and technological issues of brazing the absorbing tiles and cooling have been solved. Brazing quality is controlled by IR thermograms. First warm measurements of a prototype load are expected this summer.
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MOPCH189 | Calculating the Muon Cooling within a MICE Liquid Absorber | scattering, cryogenics, factory, focusing | 502 | ||||
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The key elements of the Muon Ionization Cooling Experiment (MICE) cooling channel are the absorbers that are a part of the MICE absorber focus coil modules (AFC modules). The boundaries of room temperature solid absorbers are well defined. The density of most solid absorber materials is also well understood. The properties of solid absorber are most certainly understood to 0.3 percent. The MICE liquid absorbers are different in that their dimensions are a function of the absorber temperature and the fluid pressure within the absorber. The second element in the liquid absorber is the variability of the liquid density with temperature and pressure. While one can determine the absorber boundary within 0.3 percent, the determination of the liquid density within 0.3 percent is more difficult (particularly with liquid helium in the absorber). This report presents a method of calculating absorber boundary and the cooling performance of the MICE absorbers as a function of fluid temperature and pressure.
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MOPLS024 | RHIC Performance as Polarized Proton Collider in Run-6 | polarization, RHIC, luminosity, AGS | 592 | ||||
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The Relativistic Heavy Ion Collider in Run-6 was operating in polarized proton mode. With two Siberian Snakes per ring, the polarized protons were brought into collisions at 100 Gev and 31.2 Gev energies. The control of polarization orientation at STAR and PHENIX experiments was done using helical spin rotators. Physics studies were conducted with longitudinal, vertical and radial beam polarization at collision points. This paper presents the performance of RHIC as a polarized proton collider in the Run-6 with emphasis on beam polarization and luminosity issues.
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MOPLS025 | Experience in Reducing Electron Cloud and Dynamic Pressure Rise in Warm and Cold Regions in RHIC | electron, proton, RHIC, luminosity | 595 | ||||
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Significant improvement has been achieved for reducing electron cloud and dynamic pressure rise at RHIC over several years; however, there remain to be factors limiting luminosity. The large scale application of non-evaporable getter (NEG) coating in RHIC has been proven effective in reducing electron multipacting and dynamic pressure rise. This will be reported together with the study of the saturated NEG coatings. Since beams with increased intensity and shorter bunch spacing became possible in operation, the electron cloud effects on beam, such as the emittance growth,are an increasing concern. Observations and studies are reported. We also report the study results relevant to the RHIC electron cloud and pressure rise improvement, such as the effect of anti-grazing ridges on electron cloud in warm sections, and the effect of pre-pumping in cryogenic regions.
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MOPLS027 | Beam-beam Simulations for a Single Pass SuperB-factory | luminosity, linac, simulation, damping | 601 | ||||
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A study of beam-beam collisions for an asymmetric single pass SuperB-Factory is presented*. In this scheme an electron and a positron beam are first stored and damped in two damping rings, then extracted, compressed and focused to the IP. After collision the two beams are re-injected in the DR to be damped and extracted for collision again. The explored beam parameters are similar to those used in the design of the International Linear Collider, except for the beam energies. Very flat beams and round beams were compared in the simulations, with the GuineaPig code**, in order to optimize both luminosity performances and beam blow-up after collision. With such approach, luminosities of the order of 1036 /(cm2 sec) can be achieved.
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*http://arxiv.org/abs/physics/0512235.**D. Schulte. Study of electromagnetic and hadronic background in the Interaction Region of the TESLA Collider, PhD Thesis, Hamburg, 1996. |
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MOPLS032 | Beam-beam Limit and the Degree of Freedom | damping, simulation, luminosity, KEKB | 616 | ||||
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Beam-beam limit is caused by chaotic diffusion due to the strong nonlinear force of beam-beam interaction. Degree of freedom in the colliding system is essential for the diffusion. We discuss the diffusion using several models.
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MOPLS041 | MAD-X/PTC Lattice Design for DAFNE at Frascati | survey, collider, luminosity, lattice | 631 | ||||
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In absence of a program that takes as an input the desired or known location of the magnets in the tunnel, accelerator designers have been using MAD8/X that looks at a ring as a sequence of magnets without a connection to the tunnel. In many simple examples that is just fine, but once more complicated structures are treated one is bound to play tricks with MAD. Here PTC comes to the rescue. It is shown how pieces of this machine that exist in MAD-X format are used in PTC to create this double ring, as found in the tunnel, with a proper survey in the forward and backward direction. Special elements have been implemented in MAD-X to allow the full PTC description of the machine. It is discussed how this real PTC model differs from the 'fake' MAD-X model and how well PTC describes the real machine.
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MOPLS047 | Design of an Asymmetric Super-B Factory | collider, luminosity, interaction-region, factory | 646 | ||||
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Submitted for the High Luminosity Study Group for an Asymmetric Single-pass Super-B Factory: Parameters are being studied for a high luminosity e+e- collider operating at the Upsilon 4S that would deliver a luminosity of over 1036/cm2/s. This collider would use a novel combination of linear collider and storage ring techniques. In this scheme an electron beam and a positron beam are first stored in fast-damping and low-emittance damping rings, then extracted, accelerated, compressed and focused to the interaction point. After collision the two beams are decelerated and re-injected in the damping rings to be damped and extracted for collision again. The explored beam parameters are similar to those used in the design of the International Linear Collider, except for the beam energies. Design parameters for very flat beams and round beams have been studied.
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MOPLS048 | Doubling the PEP-II Luminosity in Simulations | luminosity, simulation, damping, SLAC | 649 | ||||
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The PEP-II luminosity reached 1x1034cm-2s-1 in October 2005. The question of how to increase the luminosity using modest improvements in the PEP-II accelerator in the coming years is the subject of this paper. We found that the parasitic collisions significantly degrade the simulated luminosity as the beam currents are increased from 3A and 1.7A to 4A and 2.2A in the low and high energy rings, respectively. Using the beam-beam code BBI, we systematically optimized the luminosity and showed that a luminosity of over 2x1034cm-2s-1 is achievable within the limits of machine parameters.
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MOPLS050 | Combined Phase Space Characterization at the PEP-II IP using Single-beam and Luminous-region Measurements | luminosity, lattice, coupling, simulation | 655 | ||||
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We present a novel method to characterize the e ± phase space at the IP of the SLAC B-factory, that combines single-beam measurements with a detailed mapping of luminous-region observables. Transverse spot sizes are determined in the two rings with synchrotron-light monitors & extrapolated to the IP using measured lattice functions. The 3-D luminosity distribution, as well as the spatial dependence of the transverse-boost distribution of the colliding beams, are measured using e+ e- > mu+ mu- events reconstructed in the BaBar tracking detectors; they provide information on the luminous spot size, the e- angular divergence & the vertical emittance. The specific luminosity, which is proportional to the inverse product of the overlap IP beam sizes, is continuously monitored using Bhabha-scattering events. The combination of these measurements provide constraints on the horizontal & vertical spot sizes, angular divergences, emittances & beta functions of both beams at the IP during routine high-luminosity operation. Preliminary results of this combined-spot size analysis are confronted with measurements of IP beta-functions & overlap IP beam sizes at low beam current.
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MOPLS059 | The Probe Beam Linac in CTF3 | linac, CLIC, CTF3, gun | 679 | ||||
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The test facility CTF3, presently under construction at CERN within an international collaboration, is aimed at demonstrating the key feasibility issues of the multi-TeV linear collider CLIC. The objective of the probe beam linac is to "mimic" the main beam of CLIC in order to measure precisely the performances of the 30 GHz CLIC accelerating structures. In order to meet the required parameters of this 200 MeV probe beam, in terms of emittance, energy spread and bunch-length, the most advanced techniques have been considered: laser triggered photo-injector, velocity bunching, beam-loading compensation, RF pulse compression
The final layout is described, and the selection criteria and the beam dynamics results are reviewed.
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MOPLS065 | An ILC Main Linac Simulation Package Based on Merlin | simulation, linac, alignment, klystron | 694 | ||||
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The preservation of the ultra-small vertical emittance in the International Linear Collider (ILC) will require the use of beam-based alignment techniques, the expected performance of which relies heavily on the use of simulation tools. In this report, we present the newest release of a purpose-built ILC main linac simulation tool, based on the Merlin* C++ class library. Examples of results from Dispersion Free Steering (DFS) simulations are also be presented.
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*http://www.desy.de/~merlin |
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MOPLS066 | Direct Measurement of Geometric and Resistive Wakefields in Tapered Collimators for the International Linear Collider | SLAC, linear-collider, collider, impedance | 697 | ||||
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Precise collimation of the beam halo is required in the ILC to prevent beam losses near the interaction region that could cause unacceptable backgrounds for the physics detector. The necessarily small apertures of the collimators lead to transverse wakefields that may result in beam deflections and increased emittance. A set of collimator wakefield measurements has previously been performed in the ASSET region of the SLAC LINAC. We report on the next phase of this programme, which is carried out at the recently commissioned End Station A test facility at SLAC. Measurements of resistive and geometric wakefields using tapered collimators are compared with model predictions from MAFIA and GdfidL and with analytic calculations.
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MOPLS067 | Test Beam Studies at SLAC's End Station A, for the International Linear Collider | SLAC, linac, synchrotron, linear-collider | 700 | ||||
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The SLAC Linac can deliver to End Station A a high-energy test beam with similar beam parameters as for the International Linear Collider for bunch charge, bunch length and bunch energy spread. ESA beam tests run parasitically with PEP-II with single damped bunches at 10Hz, beam energy of 28.5 GeV and bunch charge of (1.5-2.0)·1010 electrons. A 5-day commissioning run was performed in January 2006, followed by a 2-week run in April. We describe the beamline configuration and beam setup for these runs, and give an overview of the tests being carried out. These tests include studies of collimator wakefields, prototype energy spectrometers, prototype beam position monitors for the ILC Linac, and characterization of beam-induced electro-magnetic interference along the ESA beamline.
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MOPLS096 | Effects of Wake Fields in the CLIC BDS | CLIC, luminosity, quadrupole, betatron | 780 | ||||
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The wake fields due to collimators in the Beam Delivery System of CLIC are modeled using a conventional approach. According to the chosen ranges of parameters, differences in the transverse kicks due to both the geometric and resistive wall components for different regimes are highlighted (inductive or diffractive for the geometric wake fields, short- or long-range, ac or dc for the resistive wall wake fields). A module for particle tracking along the BDS including the effect of wake fields has been introduced in PLACET, and the first tracking results are shown.
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MOPLS098 | Study of an ILC Main Linac that Follows the Earth Curvature | linac, alignment, quadrupole, laser | 786 | ||||
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In the base line configuration, the tunnel of the ILC will follow the earth curvature. The emittance growth in a curved main linac has been studied, including static and dynamic imperfections. These include effects due to current ripples in the power supplies of the steering coils, the impact of the beam position monitor scale errors.
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MOPLS102 | Beam Dynamic Studies and Emittance Optimization in the CTF3 Linac at CERN | CTF3, linac, quadrupole, simulation | 798 | ||||
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Small transverse beam emittances and well-known lattice functions are crucial for the 30 GHz power production in the Power Extraction and Transfer Structure (PETS), and for the commissioning of the delay loop of the CLIC Test Facility 3 (CTF3). Following beam-dynamics-simulation results, two additional solenoids were installed in the CTF3 injector in order to improve the emittance. During the runs in 2005 and 2006, an intensive measurement campaign to determine Twiss parameters and beam sizes was launched. The results obtained by means of quadrupole scans for different modes of operation suggest rms emittances well below the nominal (100 pi mm mrad) and a convincing agreement with PARMELA simulations.
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MOPLS114 | Construction of the Probe Beam Photo-injector of CTF3 | gun, vacuum, simulation, laser | 828 | ||||
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The paper describes the HF and dynamic beam modelling performed onto the 3 GHz / 2,5 cells photo-injector of the future CTF3 (CLIC Test Facility 3) probe beam linac, whose goal is to demonstrate the feasibility of the 30 GHz accelerating sections in the framework of the CLIC project. The Probe Beam Photo-Injector (PBPI) conception is inspired from the drive beam photo-injector already designed by LAL (Orsay, France) and actually tested in our laboratory. However, the design of PBPI has been simplified with respect to the previous because the charge per bunch is 4 times lower and the number of bunches several orders of magnitude smaller. The internal geometry and the coupling system of the PBPI have been designed with 2D (SUPERFISH) and 3D (HFSS, ANSYS) codes. A detailed analysis of the dissymmetry (induced by the coupling system) of the accelerating field component has been performed. Based on the modified design, PARMELA simulations showed that the technical specifications are fulfilled. The vacuum issue has been also carefully investigated, and NEG (Non Evaporated Getter) technology has been adopted in order to reach the 10-10 mbar pressure inside the structure.
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MOPLS115 | A Spin Rotator for the ILC | linac, polarization, coupling, dipole | 831 | ||||
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A spin rotator featuring an optic axis with straight vision is presented. This rotator utilizes three bends, two solenoid pairs and two correction devices. These correctors, named reflectors, are mandatory for removing the cross plane coupling introduced by the solenoids. It is shown how the solenoids have to be set up to achieve longitudinal IP polarization taking into account non-zero crossing angles at the interaction region and a linac following the curvature of the earth. Furthermore, the stability requirements for mechanical and electrical imperfections are analyzed.
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MOPLS117 | Tuning Algorithms for the ILC Beam Delivery System | sextupole, luminosity, coupling, quadrupole | 837 | ||||
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Emittance preservation is an important aspect in the design and running of the International Linear Collider (ILC) with a direct consequence on the luminosity of the machine. The Beam Delivery System represents a major problem in this respect as it produces emittance dilution effects that are difficult to correct and that have a direct effect on the emittance as seen at the interaction point, and thus upon the luminosity of the machine. Tuning algorithms for this section of the machine rely on the correction of aberrations through the use of linear and higher order knobs, using corrections magnets distributed throughout the system. Alternative systems are also discussed. The design and implementation of these tuning algorithms, and their effectiveness in a variety of cases, are investigated and estimates made for tolerances on a variety of error sources. Simulations results are also presented for models of the ATF-2 accelerator under development at KEK, with comparisons made to the ILC design.
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MOPLS120 | Mitigation of Emittance Dilution due to Transverse Mode Coupling in the L-band Linacs of the ILC | linac, simulation, lattice, coupling | 843 | ||||
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The main L-band linacs of the ILC accelerate 2820 bunches from a center of mass of 10 GeV to 500 GeV (and in the proposed later upgrade, to 1 TeV). The emittance of the vertical plane is approximately 400 times less than that of the horizontal plane. Provided the vertical and horizontal mode dipole frequencies are degenerate, then the motion in each plane is not coupled. However, in reality the degeneracy will more than likely be removed with the eigen modes lying in planes rotated from the x and y planes due to inevitable manufacturing errors introduced in fabricating 20,000 cavities. This gives rise to a transverse coupling in the horizontal-vertical motion and can readily lead to a dilution in the emittance in the vertical plane. We investigate means to ameliorate this emittance dilution by splitting the horizontal-vertical tune of the lattice.
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MOPLS129 | Integration of the PHIN RF Gun into the CLIC Test Facility | CTF3, gun, CERN, bunching | 861 | ||||
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CERN is a collaborator within the European PHIN project, a joint research activity for Photo injectors within the CARE program. The scope of this project is to build an RF Gun equipped with high quantum efficiency Cs2Te cathodes and a laser to produce the nominal beam for the CLIC Test Facility (CTF3). The nominal beam for CTF3 has an average current of 3.5 A, 1.5 GHz bunch repetition frequency and a pulse length of 1.5 us (2310 bunches) with quite tight stability requirements. In addition a phase shift of 90 deg is needed after each train of 140 ns for the special CLIC combination scheme. This RF Gun will be tested at CERN in fall 2006 and should be integrated as a new injector into the CTF3 linac, replacing the existing injector consisting of a thermionic gun and a subharmonic bunching system. The paper studies the optimal integration into the machine trying to optimize transverse and longitudinal phase space of the beam while respecting the numerous constraints of the existing accelerator. The presented scheme uses emittance compensation and velocity bunching to fulfill the requirements.
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MOPLS130 | Implications of a Curved Tunnel for the Main Linac of CLIC | linac, quadrupole, laser, CLIC | 864 | ||||
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Preliminary studies of a linac that follows the earth's curvature are presented for the CLIC main linac. The curvature of the tunnel is modeled in a realistic way by use of geometry changing elements. The emittance preservation is studied for a perfect machine as well as taking into account imperfections. Results for a curved linac are compared with those for a laser-straight machine.
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MOPLS134 | Minimizing Emittance for the CLIC Damping Ring | wiggler, damping, CLIC, permanent-magnet | 870 | ||||
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The CLIC damping rings aim at unprecedented small normalized equilibrium emittances of 3.3 nm vertical and 550 nm horizontal, for a bunch charge of 2.6 109 particles and an energy of 2.4 GeV. In this parameter regime the dominant emittance growth mechanism is intra-beam scattering. Intense synchrotron radiation damping from wigglers is required to counteract its effect. Here the overall optimization of the wiggler parameters is described, taking into account state-of-the-art wiggler technologies, wiggler effects on dynamic aperture, and problems of wiggler radiation absorption. Two technical solutions, one based on superconducting magnet technology and the other on permanent magnets, are presented. Although dynamic aperture and tolerances of this ring design remain challenging, benefits are obtained from the strong damping. Only bunches for a single machine pulse need to be stored, making injection/extraction particularly simple and limiting the synchrotron-radiation power. With a 360 m circumference, the ring remains comparatively small.
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MOPLS135 | Correction of Vertical Dispersion and Betatron Coupling for the CLIC Damping Ring | quadrupole, sextupole, dipole, coupling | 873 | ||||
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The sensitivity of the CLIC damping ring to various kinds of alignment errors have been studied. Without any correction, fairly small vertical misalignments of the quadrupoles and, in particular, the sextupoles, introduce unacceptable distortions of the closed orbit as well as intolerable spurious vertical dispersion and coupling due to the strong focusing optics of the damping ring. A sophisticated beam-based correction scheme has been developed to bring the design target emittances and the dynamic aperture back to the ideal value. The correction using dipolar correctors and several skew quadrupole correctors allows a minimization of the closed-orbit distortion, the cross-talk between vertical and horizontal closed orbits, the residual vertical dispersion and the betatron coupling.
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MOPLS138 | Space Charge and Equilibrium Emittances in Damping Rings | space-charge, damping, lattice, radiation | 882 | ||||
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The unusual combination of small beam size and long ring circumference may cause space charge to have noticeable effects on the beam dynamics of the ILC (International Linear Collider) damping rings. One possible consequence is a modification of the vertical equilibrium emittance resulting from a non-ideal lattice. One simple way to account for this effect is to model space charge in the linear approximation within the framework of Oide's envelope (or Chao's matrix) formalism, whis is commonly used to calculate equilibrium emittances in lepton storage rings. However, this model would likely overestimate the effect as a linear approximation for space charge is accurate only in a small neighborhood of a bunch center. For a more accurate modelling, we propose to make use of Sacherer's envelope equations consisting of a closed set of equations for the second moments of a beam distribution that account for the nonlinear dependence of the space-charge force. Here we will illustrate how Sacherer's equations can be combined with Oide's formalism and apply the result to the ILC damping rings.
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MOPLS140 | Tuning Algorithms for the ILC Damping Rings | damping, quadrupole, coupling, dipole | 888 | ||||
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Emittance preservation is an important aspect in the design and running of the International Linear Collider with a direct consequence on the luminosity of the machine. One major area of concern is in the damping rings, where the extracted emittances set the effective lower limits for the rest of the machine. Algorithms for tuning this system have been investigated, and simulations have been performed to understand the design and implementation issues. The different algorithms have been applied to the various damping ring designs, and the effectiveness of each algorithm has been assessed. A preliminary recommendation of tuning algorithm, and its effectiveness under various conditions, is given.
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MOPLS141 | The Proposed Conversion of CESR to an ILC Damping Ring Test Facility | damping, wiggler, electron, positron | 891 | ||||
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In 2008 the Cornell Electron Storage Ring (CESR) will end nearly three decades of providing electron-positron collisions for the CLEO experiment. At that time it will be possible to reconfigure CESR as a damping ring test facility, CesrTF, for the International Linear Collider (ILC) project. With its complement of 12 damping wigglers, CesrTF will offer horizontal emittances in the few nanometer range and, ideally, vertical emittances approaching those specified for the ILC damping rings. An important feature of the CesrTF concept is the ability to operate with positrons or electrons. Positron operation will allow detailed testing of electron cloud issues critical for the operation of the ILC positron damping rings. Other key features include operation with wigglers that meet or exceed all ILC damping ring requirements, the ability to operate from 1.5 to 5.5 GeV beam energies, and the provision of a large insertion region for testing damping ring hardware. We discuss in detail the CesrTF machine parameters, critical conversion issues, and experimental reach for damping ring studies.
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TUZBPA01 | The ERL High Energy Cooler for RHIC | electron, RHIC, ERL, luminosity | 940 | ||||
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This talk will first briefly review high-energy electron cooling, including the recent results from Fermilab. The main empasis will be on describing the proposed electron-cooling device for RHIC, based on an Energy Recovery Linac. Finally, results from the prototype ERL will presented.
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Transparencies
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TUXFI01 | FFAG Accelerators and their Applications | acceleration, proton, focusing, target | 950 | ||||
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This talk will give an introduction to the FFAG concept and review the present development of FFAG accelerators. It will also discuss the use of FFAGs for applications such as hadron therapy, neutron generation, BNCT, ADS, and muon acceleration.
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Transparencies
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TUPCH009 | Beam Measurements and Manipulation of the Electron Beam in the BESSY-II Transferline for Topping Up Studies | synchrotron, quadrupole, booster, injection | 1010 | ||||
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The BESSY-II storage ring based synchrotron radiation source will be upgraded to allow for continuous topping up operation. In order to achieve a high injection efficiency between the booster synchrotron and the storage ring, the transferline will be equipped with novel beam size monitors and collimators. This paper describes the collimator design and first beam measurements of the transverse emittance. The transverse emittance is measured using the quadrupole scan technique. The data taking and the analysis procedure is given together with results and comparision with simulations.
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TUPCH014 | Machine Protection by Active Current-transmission Control at GSI-UNILAC | UNILAC, controls, GSI, ion | 1025 | ||||
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Toroidal beam current transformers (BCT) are installed at dedicated locations along the UNILAC accelerator. They provide an output signal with a fixed transimpedance. Dedicated signal pairs from consecutive transformers drive differential integrator stations. If preset protection levels are exceeded due to beam charge loss during the macro-pulse, fast interlock signals are generated. The actual beam pulse is instantaneously truncated by a fast beam chopper, avoiding any thermal damage or radio-activation of machine components. |
A new BCT macro-pulse selector/display is presently under construction, which will provide time structure observation of multiple UNILAC macro-pulses, as well as long-term data logging. The hardware is set up with PXI components from National Instruments, running a multi-client/server controller software under LabViewRT®. Offline-analysis of the accumulated BCT data is expected to improve the protection system's operation and reliability. An overview of the system layouts, technical details, and relevant operational results will be presented. |
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TUPCH019 | Laser-based Beam Diagnostic for the Front End Test Stand (FETS) at RAL | laser, electron, ion, dipole | 1037 | ||||
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High power proton accelerators (HPPA) are required for several future projects like spallation sources or a neutrino factory. Compared with existing machines the beam power therefore has to be increased by a factor of 30. The Front end test stand at RAL is being built to demonstrate that a chopped Hminus beam of 60 mA at 3 MeV with 50 pps and sufficiently high beam quality, as required for all proposed Proton drivers, can be built. For the test stand a comprehensive set of beam diagnostics is also required. Due to the high beam energy and power non destructive diagnostic methods are favorable. Hminus beams offer the possibility to use intense laser light to detach the additional electron and use the produced particles for beam diagnostics. The principle is appropriate to determine the transversal beam density distribution as well as the transversal and longitudinal beam emittance in front and behind the RFQ. A detailed layout of the beam diagnostics including a discussion of the predicted spatial and temporal resolution and the dynamic range of the proposed devices will be presented.
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TUPCH037 | Development of Emittance Scanner Software for ISIS | controls, ion-source, ion, target | 1085 | ||||
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Horizontal and vertical Faraday cup and slit scanners are used on ISIS, the 800MeV pulsed neutron source at the Rutherford Appleton Laboratory, to calculate the emittance of the beam. Software has been written in C++ to control the scanners, acquire and display beam data and compute an emittance value for the beam. The software allows the user more control, and has the ability to scan over a wider range, than was previously available.
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TUPCH048 | A Study of Emittance Measurement at the ILC | laser, electron, quadrupole, coupling | 1115 | ||||
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The measurement of the ILC emittance in the ILC beam delivery system and the linac is simulated. Estimates of statistical and machine-related errors are discussed and implications for related diagnostics R&D are inferred.
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TUPCH058 | Very Small Beam Size Measurement by Reflective SR Interferometer at KEK-ATF | optics, coupling, damping, KEK | 1142 | ||||
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An SR interferometer with the Herschelian reflective optics has been developed for the measurement of several um beam size. The chromatic aberration of the optical system applied in the SR interferometer limits the resolution of SR interferometer. We used objective lens of the SR interferometer by a focusing mirror. For the convenience of observation of the interferogram, we applied Herschelian arrangement of the optics. The measured vertical beam size was less than 5um and the estimated vertical emittance was 1x10-11m at the KEK-ATF damping ring.
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TUPCH060 | Beam Collimator System in the J-PARC 3-50BT Line | LEFT, synchrotron, injection, quadrupole | 1148 | ||||
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For the J-PARC 50 GeV Main Ring Synchrotron (MR), the design beam emittance is 54 pi mm mrad. On the other hand, the 3 GeV beam from the Rapid Cycling Booster Synchrotron (RCS) may have a large halo component upto 216 pi mm mrad. In order to absorb the halo component, a beam collimator system will be installed in the beam transport line called as the 3-50BT, which connects the RCS and the MR. From the view of the hands-on maintenance, high endurance structure is adopted. The beam collimator design including the beam optics is reported in this paper.
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TUPCH067 | Time-resolved Beam Emittance Measurement of Dragon-I Linear Induction Accelerator | radiation, focusing, induction, electron | 1166 | ||||
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A beam emittance diagnostic system of an intense pulsed electron beam (20MeV, 2.6kA, 80ns) based on optical transition radiation is developed. A gated CCD camera is used to get time-resolved result. We develop a timing system to avoid the time jitter, an anti-interference system to avoid the electromagnetic interference, and a C++ code to deal with the experimental data. The measured emittance is about 2000¦Ð.mm.mrad, which is agree with the result of three gradient method.
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TUPCH075 | Dependence of the Electron Beam Polarization Effect in the Intra-beam Scattering Rate on the Vertical Beam Emittance | polarization, electron, scattering, coupling | 1184 | ||||
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Measurement of the Intra-beam scattering rate is applied in the resonant depolarization technique to detect beam polarization in electron/positron storage rings. A depolarization jump in the counting rate of scattering particles occurs at the instant when the beam becomes unpolarized due to fulfillment of the external spin resonance condition. The magnitude of the jump depends on polarization quadratically. It also depends on some other beam parameters as well as the position of counters relative to the beam orbit. A larger jump implies higher accuracy in absolute calibration of particle energy because the latter is proportional to the spin precession frequency. In contrast to an ordinary one-dimensional approach, we calculate the magnitude of jump subject to, among other things, the vertical component of relative velocity in particle collisions inside the beam. For this purpose, the transverse momentum distribution function is properly modified. Calculations performed for the VEPP-4M storage ring-collider show that the jump may depend significantly on the ratio between the vertical and radial beam emittance. We present results of our recent experiments on study of this dependence.
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TUPCH090 | Electron Beam Profile Measurements with Visible and X-ray Synchrotron Radiation at the Swiss Light Source | synchrotron, SLS, synchrotron-radiation, radiation | 1223 | ||||
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Two different methods of beam profile measurements using a) visible-to-UV range synchrotron radiation b) X-ray synchrotron radiation have been realized in a single diagnostics beam line at the Swiss Light Source. While the visible-to-UV part uses a focusing lens to create an image of the electron beam cross section, the X-ray part makes use of the pinhole camera principle. In the visible-to-UV case the vertically polarized synchrotron radiation renders an image heavily influenced by inherent emission and diffraction effects of synchrotron radiation. This turns out to be an advantageous influence in order to determine ultra small beam profiles. For each of the two methods practical point-spread function measurements, including all beam line components, and high-precision wave-optics based calculations (SRW code) of the synchrotron light characteristics were performed to ensure correct interpretation of the measured profiles. Results from both monitors will be presented to allow comparison.
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TUPCH098 | Antiproton Momentum Distributions as a Measure of Electron Cooling Force at the Fermilab Recycler | electron, antiproton, betatron, scattering | 1241 | ||||
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The Fermilab Recycler is a fixed 8GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel near the ceiling. Electron cooling of high-energy antiprotons has recently been demonstrated at the Recycler. Antiproton beam Schottky signals were used to measure the antiproton momentum distribution at equilibrium between a calibrated broadband diffusion source and electron cooling. The large Recycler momentum aperture, the dependence of the electron cooling force as a function of the antiproton momentum deviation and the calibrated diffusion source combine to give a unique spectral measurement of the antiproton momentum beam distribution.
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TUPCH108 | Characterization of the PEP-II Colliding-beam Phase Space by the Boost Method | positron, electron, coupling, simulation | 1262 | ||||
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We present a novel approach to characterize the colliding-beam phase space at the interaction point of the energy-asymmetric PEP-II B-Factory. The method exploits the fact that the transverse-boost distribution of e+ e- > mu+ mu- events reconstructed in the BaBar tracking system, reflects that of the colliding electrons & positrons. The average boost direction, when combined with the measured orientation of the luminous ellipsoid, determines the e+e- crossing angles. Varying the horizontal direction of one beam with respect to the other in a controlled fashion allows to estimate the individual e+ and e- horizontal IP beam sizes. The angular spread of the transverse boost vector provides an accurate measure of the angular spread of the incoming high-energy beam, confirming the presence of a significant beam-beam induced increase of this angular spread. In addition, the longitudinal dependence of the angular spread of the boost vector in the y-z plane allows to extract from the continuously-monitored boost distributions, a weighted average of the vertical IP beta-functions & emittances of the two beams representative of routine high-luminosity operation.
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TUPCH112 | Commissioning of the 100 MeV Preinjector HELIOS for the SOLEIL Synchrotron | linac, gun, beam-loading, SOLEIL | 1274 | ||||
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HELIOS is the 100 MeV electron linac pre-injector of SOLEIL the new French SR facility. It has been supplied by THALES, as a turn-key system on the basis of SOLEIL APD design. The linac was commissioned in October 2005. This paper will remind the main features of the linac, especially on beam-loading compensation, and will give results obtained during the commissioning tests where a special care has been taken for emittance measurements. Specified and measured beam parameters will be compared to show the performance of the entire system.
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TUPCH148 | 201 MHz Cavity R&D for MUCOOL and MICE | vacuum, factory, collider, coupling | 1367 | ||||
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We describe the design, fabrication and preliminary testing of the prototype 201 MHz copper cavity for a muon ionization cooling channel. Application of the cavity includes the Muon Ionization Cooling Experiment (MICE) as well as cooling channels for a neutrino factory or a muon collider. This cavity was developed by the US MUCOOL collaboration and is being tested in the MUCOOL Test Area (MTA) at Fermilab. In order to achieve a high accelerating gradient, the cavity beam irises are terminated by a pair of curved, thin beryllium windows. Several of the fabrication methods developed for this cavity and the windows are novel and offer significant cost savings compared to conventional construction methods. Cavity thermal and RF performance will be compared to FEA modeling predictions. RF commissioning results will be presented.
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TUPCH152 | MICE RF Test Stand | factory, power-supply, target, controls | 1379 | ||||
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The Muon Ionization Cooling Experiment (MICE) RF test stand is being assembled at Daresbury Laboratory. This will provide a test bed for power amplifiers to produce the 2MW 200MHz RF for the MICE experiment RF cavities. Initial design and proposed layout of the RF system are described.
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TUPCH160 | Novel Conception of Beam Temperature in Accelerator and Applications | klystron, electron | 1400 | ||||
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In this paper, we will introduce a novel conception of beam temperature in accelerator, discuss the calculation method. And finally the author will show an example on the beam temperature in a klystron.
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TUPLS010 | New Beam Transport Line from LINAC to Photon Factory in KEK | linac, KEKB, injection, optics | 1505 | ||||
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The e+/e- injector LINAC in KEK usually injects into four rings which are Low Energy Ring (LER) of KEKB (3.5GeV/e+), High Energy Ring (HER) of KEKB(8.0GeV/e-), Photon Factory (PF)(2.5GeV/e-) and Advanced Ring for pulse x-rays (PF-AR)(3.0GeV/e-). While LINAC continuously injects into LER and HER alternately about every five minutes, both of the KEKB rings usually store almost full operating currents. Time for PF or PF-AR, which includes switching time, took about 20 minutes several times a day. During this, the storage currents in KEKB rings decreased, and the optimum points of luminosity tuning had been lost. It had taken more than two hours to recover the luminosity. It is so useful for KEKB to shorten the time for switch LINAC KEKB to/from PF or PF-AR. In summer of 2005, the transport line from LINAC to PF were renewed, in which a DC bending magnet only for PF line apportions electron beam from the end of LINAC to the new line. We succeeded to reduce the occupancy time for PF injection to about five minutes. In this paper design of the new PF beam transport line and the practical performance achieved according to the design are described.
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TUPLS014 | Optics Flexibility and Dispersion Matching at Injection into the LHC | injection, LHC, optics, controls | 1517 | ||||
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The LHC requires very precise matching of transfer line and LHC optics to minimise emittance blow-up and tail repopulation at injection. The recent addition of a comprehensive transfer line collimation system to improve the protection against beam loss has created additional matching constraints and consumed a significant part of the flexibility contained in the initial optics design of the transfer lines. Optical errors, different injection configurations and possible future optics changes require however to preserve a certain tuning range. Here we present methods of tuning optics parameters at the injection point by using orbit correctors in the main ring, with the emphasis on dispersion matching. The benefit of alternative measures to enhance the flexibility is briefly discussed.
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TUPLS024 | FFAGs as Muon Accelerators for a Neutrino Factory | resonance, acceleration, alignment, beam-losses | 1541 | ||||
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The FFAG accelerator is a solution for rapid acceleration of muons because of its large aperture and no need of magnet ramping. Its particle dynamics is, however, peculiar due to high energy gain per turn and large transverse amplitude, which has not been seen in other types of circular accelerators. One variation of FFAG, called non-scaling FFAG, employs quite new scheme, namely, out of bucket acceleration. We studied emittance distortion, coupled motions among 3-D planes, effects of resonance lines, etc., based on a newly developed tracking code. In this paper, we will emphasize new regime of particle dynamics as well as a modeling technique of FFAG.
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TUPLS038 | The MAFF IH-RFQ Test Stand at the IAP Frankfurt | rfq, ion, ion-source, quadrupole | 1577 | ||||
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The IH-type RFQ for the MAFF project at the LMU in Munich is presently under construction and will be integrated into a beam test stand at the IAP in Frankfurt. It is the second RFQ following the IH resonator concept and the first one that can be directly compared to a very similar 4-rod type machine, namely the REX-ISOLDE RFQ at CERN. The MAFF RFQ has been designed to accelerate rare isotope beams (RIBs) with mass to charge ratios up to 6.3 from 3 keV/u to 300 keV/u at an operating frequency of 101.28 MHz with an electrode voltage of 60 kV. First RF-measurements have already been executed and can be compared to appropriate simulation results. Parts of the test stand are currently under construction, such as the volume ion source for He+ at an extraction voltage of 12 keV and an electrostatic quadruplet for injection with an integrated steering system. These tests and accompanying theoretical investigations will be done with special respect to the applicability of such normal conducting RFQ accelerators to the EURISOL post accelerator.
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TUPLS039 | Proposal of a Normal Conducting CW-RFQ for the EURISOL Post-accelerator and a Dedicated Beta-beam Linac Concept | rfq, EURISOL, linac, ion | 1580 | ||||
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A combination of three superconducting RFQs has been proposed for the EURISOL post accelerator layout. At least the first RFQ of this triplet could be replaced by a normal conducting continuous wave (c.w.) device. Efficient cooling systems have already been designed and applied to existing machines at the IAP in Frankfurt. Preliminary electrode and cavity designs can be presented. Since a parallel use for beta-beam applications was intended, we have optimized the design not only for heavy ion applications with negligible beam currents at c.w. but also for lighter ions with currents up to 7.5 mA at pulsed operation. More recent investigations on beta-beams came up with currents around 50 mA, which then would make a separate linac solution for beta-beams necessary. We worked out some preliminary design suggestions for such a dedicated 100 MeV/u machine.
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TUPLS041 | The HITRAP RFQ Decelerator at GSI | rfq, GSI, HITRAP, ion | 1586 | ||||
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The HITRAP linac at GSI will decelerate ions from 5 MeV/u to 6 keV/u for experiments with the large GSI Penning trap. The ions, provided by the GSI accelerator facility, will be decelerated at first in the existing experimental storage ring (ESR) down to an energy of 5 MeV/u, and injected into a new IH decelerator and decelerated to 5oo keV/u. The following 4- Rod type RFQ will decelerate the ion beam from 5oo keV to 6 keV/u. The RFQ has been designed and will be built at the Institute for Applied Physics in Frankfurt. The properties of the RFQ decelerator and the status of the project will be discussed.
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TUPLS043 | Simulations for the Frankfurt Funneling Experiment | simulation, rfq, space-charge, linac | 1591 | ||||
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Beam simulations for the Frankfurt Funneling Experiment are done with RFQSim and FUSIONS. RFQSim is responsible for the beam transport through an RFQ accelerator. Behind the accelerator the particle dynamic program FUSIONS calculates the macro bunches of both beam lines through an r.f. funneling deflector. A new space charge routine has now been included. The status of the development of FUSIONS and the results of the simulations will be presented.
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TUPLS044 | The 3D Beam Dynamics with the Space Charge in the Low and Middle Energy Super-conducting Option of HIPPI | focusing, quadrupole, simulation, proton | 1594 | ||||
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For the low and middle energy of the High Intensity Proton Pulse Injector (HIPPI), a superconducting option is considered.The 3D beam dynamics simulation results in the slot and the finger-slot sections covering the energy range from 3 to 160 MeV are presented. The optimization aim is the increase of beam current together with the reduction of emittance growth, beam losses and costs. The slot structure is compared with the conventional spoke structure.
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TUPLS045 | Completion of the Commissioning of the Superconducting Heavy Ion Injector PIAVE at INFN-LNL | ion, rfq, booster, cryogenics | 1597 | ||||
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At INFN-LNL the commissioning of the injector PIAVE, based on superconducting RFQs, has been completed. All the superconducting cavities (two RFQs and 8 quarter wave resonators - QWR) have shown very satisfactory stability with respect to changes of the liquid helium pressure and microphonics. Beam parameters are very close to the nominal values. The commissioning was completed by accelerating the pilot beam 16O3+ with the PIAVE injector and the booster linac ALPI (summer 2005). Since December 2005, a number of test beams were accelerated (mainly noble gas species) with PIAVE and ALPI and delivered to user experimental stations. Regular operation will be scheduled from Fall 2006 onwards.
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TUPLS052 | Beam Dynamics of the PEFP Linac | rfq, proton, linac, quadrupole | 1612 | ||||
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The PEFP Linac consists of a 50 keV ion source, LEBT, 3 MeV RFQ, 20 MeV DTL called DTL1, MEBT, and 100 MeV DTL called DTL2. The MEBT includes two small DTL tanks, which match the 20 MeV proton beams into the DTL2, and a bending magnet, which extracts the 20 MeV proton beams to the experimental hall. We will present the full beam dynamics study from the entrance of the DTL1 to the end of DTL2 with the initial beam parameters obtained from a simulation study of the RFQ. Our study focuses on the longitudinal beam matching in order to compensate the missing RF effect between every neighboring DTL tanks as well as the full beam matching between DTL1 and DTL2.
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TUPLS053 | Beam Dynamics of a High Current IH-DTL Structure for the TWAC Injector | rfq, ion, quadrupole, synchrotron | 1615 | ||||
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A powerful ion injector based on a laser ion source is needed for an efficient operation of the Tera Watt Accumulator (TWAC) complex including a heavy ion synchrotron and a storage ring, which is under progress now at ITEP, Moscow. The Interdigital H-type drift tube linac (IH-DTL) structure operating at 162 MHz is proposed for the second stage of the injector linac behind of a 81 MHz RFQ. Consisting of independently driven sections with inter-tank quadrupole triplet focusing, this structure will accelerate highly stripped ions with charge-to-mass ratios above 1/3 in the energy range from 1.57 MeV/u at the RFQ exit to 7 MeV/u. Beam currents up to 100 mA are expected for medium ions like Carbon or Aluminum. Since the rf frequency is duplicated at the entrance of the IH-DTL in order to reduce size as well as power consumption, space charge effects are dominant at full current. Beam dynamics and structure parameters are discussed in detail.
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TUPLS054 | The Isochronous Mode of the Collector Ring | ion, closed-orbit, quadrupole, octupole | 1618 | ||||
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The isochronous mode of a storage ring is a special ion-optical setting in which the revolution time of circulating ions of one species does not depend on their velocity spread. In this mode the ring can be used for mass measurement of exotic nuclei. The Collector Ring (CR) [1] of the FAIR project [2] will operate in such mode as time-of-flight spectrometer for short-lived exotic nuclei (T1/2 > 20 μs) produced and selected in flight with the Super-FRS fragment separator [3]. This technique has been developed at the ESR [4]. The dependence of the revolution time in the isochronous ring from its transverse acceptance, the closed orbit distortion, and nonlinear imperfection of the magnet field was investigated analytically and with a Monte-Carlo simulation. The corresponding results will be presented.
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References: [1] A. Dolinskii et. al., GSI Annual Report, 2004 [2] W. Henning, Nucl. Phys. A721 (2003)211c [3] H. Geissel, et. al., Nucl. Instr. Meth. B204 (2003)71 [4] M. Hausmann et. al., Nucl. Instr. Meth. A 446 (2000)569 |
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TUPLS057 | Linac4, a New Injector for the CERN PS Booster | linac, rfq, CERN, SCL | 1624 | ||||
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The first bottle-neck towards higher beam brightness in the LHC injector chain is due to space charge induced tune spread at injection in the CERN PS Booster (PSB). A new injector called Linac4 is proposed to remove this limitation. Using RF cavities at 352 and 704 MHz, it will replace the present 50 MeV proton Linac2, and deliver a 160 MeV, 40 mA H beam. The higher injection energy will reduce space charge effects by a factor of 2, and charge exchange will drastically reduce the beam losses at injection. Operation will be simplified and the beam brightness required for the LHC ultimate luminosity should be obtained at PS ejection. Moreover, for the needs of non-LHC physics experiments like ISOLDE, the number of protons per pulse from the PSB will increase by a significant factor. This new linac constitutes an essential component of any of the envisaged LHC upgrade scenarios, which can also become the low energy part of a future 3.5 GeV, multi-megawatt superconducting linac (SPL). The present design has benefited from the support of the French CEA and IN2P3, of the European Union and of the ISTC (Moscow). The proposed machine and its layout on the CERN site are described.
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TUPLS077 | Development of FFAG-ERIT Ring | target, proton, storage-ring, simulation | 1675 | ||||
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An intense neutron source with the emittance recovery internal target (ERIT) using the FFAG accelerator is under development. The design of the FFAG storage ring for this purpose will be presented.
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TUPLS081 | Flat Beams and Application to the Mass Separation of Radioactive Beams | ion, dipole, quadrupole, heavy-ion | 1687 | ||||
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The notion of flat beam is now well established and has been proven theoretically and experimentally with applications for linear colliders. In this paper, we propose a new and simple demonstration of the "flat beam theorem", and a possible application in the frame of radioactive ion beams (RIB) production. It consists in using a magnetized multi-specie heavy ion beam extracted from a high frequency ECR source, decoupling the transverse phase planes in such a way to obtain a very small emittance in the horizontal one, and using a dipole to separate the isotopes. A design of such a transport and separation line will be proposed and commented.
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TUPLS090 | LEBT Simulations and Ion Source Beam Measurements for the Front End Test Stand (FETS) | ion, ion-source, simulation, space-charge | 1714 | ||||
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The Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) is intended to demonstrate the early stages of acceleration (0-3MeV) and beam chopping required for high power proton accelerators, including proton drivers for pulsed neutron spallation sources and neutrino factories. Optimisation of the beam focussing within the Low Energy Beam Transport (LEBT) is necessary to minimise beam losses upon acceleration within the FETS RadioFrequency Quadrupole (RFQ). Simulations of the LEBT are currently under way using the General Particle Tracer package (GPT). Previous envelope calculations suggest weak and strong focussing solutions for the LEBT solenoids. Definitive beam dynamics simulations in GPT require further measurements of the transverse emittances and beam profile of the ion source beam, due to the sensitivity of the simulations on the initial beam profile and level of space charge compensation. A pepperpot emittance/profile measurement system has been designed for use on the ISIS ion source development rig. Results from this pepperpot system are used to constrain the initial conditions for the GPT simulations.
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TUPLS104 | Matching of High Intensity Ion Beams to an RFQ: Comparison of PARMTEQ and IGUN Simulations | rfq, ion, simulation, ion-source | 1741 | ||||
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The classical way of matching an ion source to the low energy accelerator RFQ generally is performed by adjusting the matching optics of the LEBT to provide the rms ellipse twiss parameter requirements of the RFQ shaper section. By matching to the rms parameters (the equivalent rms beam method) the actual shape of the distribution plays a smaller role according to F. Sacherer. In many cases, however, the matching optics are creating not only aberrations to the ion beam but also a very non-elliptical shape of the emittance figure, and a more exact match may be required. As a way out, an ion extraction program (IGUN) has been modified to also take into account the rf-focusing of non-modulated RFQ vanes in the shaper section. This makes it feasible to use this program for the simulation from the ion source plasma until the beginning of modulation inside the RFQ, and it can also handle dc fields in the injection region of the RFQ. In order to demonstrate the differences of both approaches we apply them to well defined experimentally proved designs of RFQ shaper sections.
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TUPLS109 | Present Status of the L3BT for J-PARC | injection, simulation, quadrupole, linac | 1756 | ||||
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L3BT is a beam transport line from J-PARC (Japan Proton Accelerator Research Complex) linac to the succeeding 3-GeV RCS (Rapid Cycling Synchrotron). The construction of the L3BT has been almost finished. The beam commissioning of the L3BT will be started soon. On the other hand we have performed 3D particle simulations with PARMILA and IMPACT to evaluate the performance of the halo scraping, momentum compaction and beam diagnostics. In this paper, results of the beam simulation of the L3BT are presented. The construction status of the L3BT is also presented in brief.
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TUPLS112 | Present Status of Injection and Extraction System of 3 GeV RCS at J-PARC | injection, extraction, proton, vacuum | 1765 | ||||
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The injection and extraction system for 3GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) have many challenging issues, in order to realize MW beam in the RCS ring. The system is consisted in 3 parts, such as the injection line, the dump line, and the extraction line. And they are constructed from many kinds of components, such as DC and pulse magnets, a charge exchange system, beam monitors, titanium and ceramic vacuum chamber, a beam dump, and so on. Up to now, final designs are accomplished and developments and experiments of some components are carried out. In this presentation, summary of the injection and extraction system, recent status of developments, and beam commissioning scheme for beam injection and extraction are introduced.
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TUPLS115 | Transverse Phase Space Painting for the CSNS Injection | injection, space-charge, simulation, lattice | 1774 | ||||
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The CSNS accelerators consist of an 80 MeV proton Linac, and a 1.6 GeV rapid cycling synchrotron (RCS). The ring accumulates 1.88*1013 protons via H-stripping injection in the phase CSNS-I. The injected beam is painted into the large transverse phase space to alleviate space-charge effects. The uniformity of beam emittance is important in reducing the tune shift/spread due to space charge effect. The paper introduces two parameters to evaluate the uniformity of a distribution. To satisfy the low-loss design criteria, extensive comparison of different painting scenarios has been carried out by using the simulation code ORBIT. This paper gives detailed studies on painting schemes and the dependence on the lattice tune, the injection peak current, and also chopping rate.
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TUPLS118 | Injection System Design for the CSNS/RCS | injection, proton, electron, linac | 1783 | ||||
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The CSNS injection system is designed to take one uninterrupted long drift in one of the four dispersion-free straight sections to host all the injection devices. Painting bumper magnets are used for both horizontal and vertical phase space painting. Closed-orbit bumper magnets are used for facilitating the installation of the injection septa and decreasing proton traversal in the stripping foil. Even with large beam emittance of about 300 pmm.mrad used, BSNS/RCS still approaches the space charge limit during the injection/trapping phase for the accumulated particles of 1.9*1013 and at the low injection energy of 80 MeV. Uniform-like beam distribution by well-designed painting scheme is then obtained to decrease the tune shift/spread. ORBIT code is used for the 3D simulations. Upgrading to higher injection energy has also been considered.
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WEYPA02 | Damping Rings towards Ultra-low Emittances | damping, wiggler, electron, kicker | 1857 | ||||
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The presentation will review the various designs of Damping Rings to achieve ultra-low emittance beams in Linear Colliders (ILC and CLIC) pointing out the major issues both from the beam dynamics and the technological point of vue and comparing the required performances with the one achieved in SLC or FFTB. It will then present the design, beam simulations, benchmarking and performances already achieved in test facilities, especially the ATF1 facility developed and operated at KEK. Finally, it will present future R&D plans and schedule in terms of beam performances, beam stability and technological development as well as the world-wide organization to achieve them.
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Transparencies
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WEOAPA02 | Optimum Frequency and Gradient for the CLIC Main Linac | linac, luminosity, CLIC, damping | 1867 | ||||
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A novel procedure for the optimization of the operating frequency, the accelerating gradient, and many other parameters of the CLIC main linac is presented. Based on the new accelerating structure design HDS (Hybrid Damped Structure), the optimization procedure takes into account both beam dynamics (BD) and RF constraints. BD constraints are related to emittance growth due to short- and long-range transverse wakefields. RF constraints are related to RF breakdown and pulsed surface heating limitations of the accelerating structure. Interpolation of beam and structure parameters in a wide range allows hundreds of millions of structures to be analyzed. Only those structures which satisfy BD and RF constraints are evaluated further in terms of ratio of luminosity to main linac input power, which is used as the figure of merit. The frequency and gradient have been varied in the range 12-30 GHz and 90-150 MV/m, respectively. It is shown that the optimum frequency varies in the range from 16 to 20 GHz depending on the accelerating gradient and that the optimum gradient is below 100 MV/m and that changing frequency and gradient can double the luminosity for the same main linac input power.
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Transparencies
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WEOAPA03 | MICE Overview - Physics Goals and Prospects | focusing, scattering, radiation, photon | 1870 | ||||
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Ionization cooling, a technique in which muon beam is passed through a series of absorbers and followed by RF-acceleration, is a proposed method for cooling muon beam, i.e., phase-space reduction. The international Muon Ionisation Cooling Experiment (MICE), which will construct and operate a realistic cooling channel and measure the beam cooling performance, is the first essential step towardsrealization of nutrino factories and eventually muon colliders based on intense muon sources. The MICE have got approved to be constructedin Rutherford Appleton Laboratory (RAL) and the fist beam commissioning is scheduled in 2007. The physics goal and future prospects of the MICE together with the beamline and the instruments which is now being built will be described.
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Transparencies
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WEYFI01 | Modelling of Space Charge and CSR Effects in Bunch Compressor Systems | CSR, simulation, space-charge, radiation | 1897 | ||||
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Bunches with high peak currents of the order of kilo-Amperes are required in linac based X-ray free electron lasers. These bunches cannot be produced directly in guns because space charge forces would destroy the brilliance within a short distance. Therefore bunches with a peak current of a few tens of Amperes are created in laser-driven radio-frequency sources and are compressed in length by two orders of magnitude. In most designs, the compression is achieved in magnet chicanes, where particles with different energies have different path lengths so that a bunch with an energy distribution correlated with longitudinal particle position can shrink in length. The principle problem is that short bunches on curved trajectories will emit coherent synchrotron radiation (CSR). The CSR effects and the space charge fields play an important role in the particle dynamic and the design of a bunch compression system. This presentation will provide an overview of computational methods and simulation tools for space charge and coherent synchrotron radiation effects in magnetic bunch compression systems.
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Transparencies
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WEOFI01 | Beam Dynamics Measurements in the Vicinity of a Half-integer Resonance | betatron, resonance, beam-beam-effects, radiation | 1902 | ||||
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The operating point of the betatron tune set near a half-integer is a crucial parameter to make high luminosity in electron/positron ring colliders. Dynamic beam-beam effects would change the optics parameters of the colliders, depending on the betatron tune and the beam-beam parameter. On the other hand, existence of the half-integer stopband makes the beam unstable. Therefore, beam behavior near a half-integer might provide interesting issues from the viewpoint of beam dynamics. We measured a frequency response of the beam across a half-integer for measuring the betatron tune at KEKB. A sharp spike just at a half-integer was observed in the tune spectrum. We believe that the spectrum would be a nonlinear resonance caused by some off-momentum particles in a bunch, not by a coherent motion of a whole bunch. The horizontal beam size measured using a synchrotron radiation monitor indicated a slight increase when the tune approached a half-integer. The variations in the beam size are discussed, considering both dynamic beam-beam effects and a beta beat due to the half-integer stopband.
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Transparencies
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WEPCH004 | Estimation of Transverse Coupling From Pinhole Images | coupling, resonance, radiation, wiggler | 1921 | ||||
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The Brazilian Synchrotron Light Laboratory (LNLS) has recently started filling its storage ring straight sections with insertion devices. Last year a 2-Tesla Wiggler was successfully installed and integrated in the control system. An elliptically polarizing undulator is now under construction and scheduled to be installed in the next shutdown, by the end of the current year. The VUV beamline for the undulator is very demanding with respect to orbit stability and other beam parameters. Considerable reduction of the vertical emittance via reduction of the transverse coupling is a must in order for the undulator beamline to achieve its promised outstanding performance. In this paper we report on recent efforts to better understand the residual coupling in the machine and we describe preliminary proposals of viable solutions that aim at controlling the linear coupling within beamline specifications.
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WEPCH016 | Spurious Vertical Dispersion Correction for PETRA III | quadrupole, wiggler, damping, closed-orbit | 1954 | ||||
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Spurious vertical dispersion, arising due to the misalignment and rotational errors of magnets in synchrotron radiation sources with low emittances, are highly undesirable as this contributes to the vertical beam size of the photon beam. This is a matter of concern in PETRA III, a 6GeV light source with a designed horizontal emittance of 1nm.rad and 1% emittance coupling. It has a hybrid lattice of FODO and DBA cells, which will be installed in one-eighth of the existing PETRA II ring. In this paper local and global vertical dispersion corrections are discussed. The global vertical dispersion is corrected using vertical corrector magnets (may also consider 12 skew quadrupole magnets), and the skew quadrupoles are used for local correction as well. Eight of them are placed close to the two damping wiggler sections used for minimizing the horizontal emittance. The remaining four are placed in the new octant with DBA cells where insertion devices are installed.
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WEPCH021 | Generalized Twiss Coefficients Including Transverse Coupling and E-beam Growth | undulator, electron, CSR, radiation | 1966 | ||||
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We use a generalization of the Twiss coefficients to the fully transverse coupled case. We show that the formalism is particularly useful to treat problems involving the beam optics of electrons propagating in undulators or solenoids. The method allows the treatment in analytical terms, we generalize the method including the effect of spatial charges and higher order multi-polar terms. The method is then applied to a specific example relevant to e-beam emittance dilution in solenoid and exotic undulators.
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WEPCH022 | Study of the Effect of Multipolar Components in the SPARC Emittance Compensation Gun Solenoid | quadrupole, multipole, gun, cathode | 1969 | ||||
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The SPARC photoinjector rf gun requires a solenoid immediately downstream for emittance compensation. The analysis of the measured solenoid magnetic maps shows the existence of multipolar components added to the pure solenoid field. The effect of these added fields on beam dynamics and possible correction schemes have been studied from the theoretical point of view and by numerical calculations based on PARMELA/TREDI codes. An accurate 3D numerical modelization by using CST EM Studio has been done, in order to investigate the source of these multipolar components and to suggest some design modifications aimed to reduce their magnitude. The results of this study are presented here.
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WEPCH030 | Beam Dynamics of a 175MHz RFQ for an IFMIF Project | rfq, coupling, linac, quadrupole | 1990 | ||||
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International Fusion Materials Irradiation Facility (IFMIF) is an accelerator-based neutron irradiation facility employing the D-Li stripping reaction, to produce the neutron field similar to the D-T Fusion reactor (2MW/m2, 20 dpa/year for Fe). The required beam current of 250 mA is realized by two beam lines of 125mA, and the output energies at injector, RFQ and DTL were designed to be 0.1, 5 and 40 MeV, respectively. The operation frequency of 175MHz was selected to accelerate the large current of 125mA. After an intensive beam simulation, the RFQ with a total length of 12.6 m was designed to keep the minimum emittance growth with the RF injection power of 2.3MW CW. For such a 12m-long RFQ, two coupling plates are indispensable in order to suppress higher modes in a longitudinal direction at least. From beam dynamics point views, the transmission co-efficient has been evaluated by TOUTATIS code, and it is found that the transmission decay within 0.5% can be achieved by employing a gap width of less than 4mm for a coupling plate design.
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WEPCH036 | Design of Short Bunch Compressors for the International Linear Collider | linac, damping, optics, acceleration | 1999 | ||||
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We present a two-stage bunch compressor system that was selected as alternative design in the ILC BCD (baseline configuration design). Initial beam with bunch length of 6 mm rms can be compressed to 150 micron rms in the bunch compressor, but the system uses a single chicane for each stage of compression, rather than the 12 chicanes used in the baseline design. We present the design scheme and performances of the system in detail, including scheme for emittance tuning in the system.
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WEPCH038 | Nonlinear Characteristics of the TME Cell | betatron, resonance, sextupole, lattice | 2002 | ||||
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The TME (Theoretical Minimum Emittance) cell is being used now for designing the lattice of different storage rings (SR sources, damping rings, FFAG accelerators, etc.). Strong sextupoles required to correct the natural chromaticity of the lattice reduce the dynamic aperture. In the paper we consider the main features of the nonlinear perturbation strength and its connection with the essential lattice parameters: horizontal emittance, betatron tunes, and natural chromaticity. The analytical results are compared with the computer simulation.
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WEPCH049 | Closed Orbit Correction of TPS Storage Ring | closed-orbit, dipole, quadrupole, synchrotron | 2029 | ||||
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A 3 GeV synchrotron storage ring is proposed in Taiwan to serve the synchrotron light users, especially for the x-ray community. The ring consists of 24 double-bend cells with 6-fold symmetry and the circumference is 518.4 m. The designed natural emittance with slightly positive dispersion in the straight sections is less than 2 nm-rad. This low emittance lattice structure needs strong quadrupoles and sextupoles and the closed orbit distortions are sensitive to the alignment errors in the quadrupoles and sextupoles as well. The closed orbit distortions due to tolerable magnetic errors are simulated and the correction scheme is proposed. Using singular value decomposition method, the closed orbit distortions are corrected and corrector strengths as well as the residual closed orbit distortions are obtained.
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WEPCH050 | Correction of Vertical Dispersion and Betatron Coupling for the TPS Storage Ring | coupling, quadrupole, sextupole, betatron | 2032 | ||||
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A proposed 3 GeV Taiwan Photon Source (TPS) is a low emittance (1.7 nm-rad) medium energy storage ring with 24 DBA cells. The vertical emittance due to betatron coupling and spurious vertical dispersion generated by the magnet errors and off-center orbits in sextupoles and quadrupoles are analyzed. The sensitivities due to magnetic alignment errors are estimated. Using the SVD method, the result of global vertical dispersion and betatron coupling correction is presented.
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WEPCH054 | Matrix Formalism for Current-independent Optics Design | focusing, optics, space-charge, cathode | 2044 | ||||
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Matrix formalism has been a powerful tool for beam optics designs. It not only facilitates computations but also plays an important role in formulating various design concepts. Here we extend the standard matrix formalism for the purpose of designing an optics that transports space-charge-dominated intense beam. Furthermore, we explore the concept of current-independent optics, which can be useful for systems such as high-brightness injectors and space-charge-dominated rings. Our discussion here is preliminary and limited to axisymmetric systems.
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WEPCH081 | Injection of The Proton Beam Into The Compact Cyclotron with Solenoid | cyclotron, injection, simulation, space-charge | 2110 | ||||
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The proton (H-) low (100 mkA) intensity beam injected by means of the solenoid comes to the first cyclotron orbit without the beam emittance deterioration. This is demonstrated by computer simulation.
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WEPCH097 | Beam Dynamics in Compton-ring Gamma Sources | laser, electron, synchrotron, simulation | 2143 | ||||
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Electron storage rings with a laser cavity are promising intensive sources of polarized hard photons to generate polarized positron beams. The dynamics of electron bunches circulating in a storage ring and interacting with high-power laser pulses is studied both analytically and by simulation. Common features and difference in the bunch behavior interacting with an extremely high power laser pulse (polarized positron source for the ILC project) and a moderate pulse (source for CLIC) are shown. Also considerations on particular lattice designs for both rings are presented.
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WEPCH101 | Ion Motion in the Adiabatic Focuser | ion, electron, focusing, plasma | 2149 | ||||
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The Adiabatic Focuser* works by having a focusing channel whose strength increases with distance down the channel. In this situation electrons of various energies and various transverse oscillation phase all are transversely focused. The concept works with external focusing, but would be very effective in a plasma ion focusing channel where the density of ions is simply increased as one goes down the channel. In the original work (Ref 1) motion of the ions was not included (as it was assumed to be a small effect). Recently, it has been suggested that ion motion in an adiabatic focuser would be significant and, even, preclude operation of the focuser as previously envisioned**. In this paper we numerically study the ion motion in the focuser. The ions clearly influence each other and, most importantly, are influenced by the electric field of the electrons being focused. It is shown that parameters can be selected such that the adiabatic focuser works as well as originally envisioned.
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*P. Chen et al. Phys. Rev. Lett. 64, 1231 (1990).**J. R. Rosenzweig, et al. Phys. Rev. Lett. 95, 195002 (2005). |
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WEPCH103 | Ion Effects in the Electron Damping Ring of the International Linear Collider | ion, damping, electron, ion-effects | 2155 | ||||
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Ion-induced beam instabilities and tune shifts are critical issues for the electron damping ring of the International Linear Collider (ILC). To avoid conventional ion trapping (multi-turn trapping), a long gap is introduced in the electron beam by omitting a number of successive bunches out of a long train. However, the beam can still suffer from the fast ion instability (FII), driven by ions that last only for a single passage of the electron bunches. Our study shows that the ion effects can be significantly mitigated by using multiple gaps, so that the stored beam consists of a number of relatively short bunch trains. The ion effects in the ILC damping rings are investigated using both analytical and numerical methods.
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WEPCH104 | Observation of the Long-range Beam-beam Effect in RHIC and Plans for Compensation | RHIC, LHC, simulation, beam-losses | 2158 | ||||
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At large distances the electromagnetic field of a wire is the same as the field produced by a bunch. Such a long-range beam-beam wire compensator was proposed for the LHC, and single beam tests with wire compensators were successfully done in the SPS. RHIC offers the possibility to test the compensation scheme with colliding beams. We report on measurements of beam loss measurements as a function of transverse separation in RHIC at injection, and comparisons with simulations. We present a design for a long-range wire compensator in RHIC.
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WEPCH107 | Contributors to AIRIX Focal Spot Size | target, ion, electron, simulation | 2164 | ||||
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High intensity electron beam focusing is a key issue for the successful development of flash radiography at hydro test facilities. AIRIX is a 2 kA, 19 MeV, 60 ns, single shot linear accelerator that produces X-rays from the interaction between relativistic electrons and a Tantalum solid target (Ta). A simulation tool has been developed to model the pulsed-beam dynamics through the accelerator from the cathode to the target. This simulator has allowed to estimate the contribution to the beam size on the target (focal spot) of beam emittance, pulse energy dispersion, pulse rising and falling fronts and the ion production on the target. The quantified contributions of these phenomena are reviewed here.
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WEPCH125 | New Design Tools for a Cyclotron Central Region | cyclotron, ion, injection, simulation | 2215 | ||||
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A code that allows us to design the spiral inflector and the central region of the SCENT cyclotron was implemented. The code integrates the main equations of motion of a particle in an electromagnetic field and provides an useful interface to describe the geometry and the physical constraints of the inflector and the central region to be simulated. The mechanical drawings of the inflector and the central region is made using a standard CAD. These drawings are then imported in OPERA 3D to produce the maps of the electric and magnetic field. An application interface allows us to enter the emittance and the particles distributions to be transported through the inflector. An iterative process to design the central region was also developed and tested.
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WEPCH138 | Simulations of Long-range Beam-beam Interaction and Wire Compensation with BBTRACK | simulation, LHC, RHIC, luminosity | 2245 | ||||
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We present weak-strong simulation results for the effect of long-range beam-beam collisions in LHC, SPS, RHIC and DAFNE, as well as for proposed wire compensation schemes or wire experiments, respectively. In particular, we discuss details of the simulation model, instability indicators, the effectiveness of compensation, the difference between nominal and PACMAN bunches for the LHC, beam experiments, and wire tolerances. The simulations are performed with the new code BBTRACK.
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WEPCH146 | Intrabeam Scattering Studies for the ILC Damping Rings Using a New Matlab Code | wiggler, damping, lattice, positron | 2266 | ||||
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A new code to calculate the effects of intrabeam scattering (IBS)has been developed in Matlab based on the approximation suggested by K. Bane*. It interfaces with the Accelerator Toolbox** but can also read in lattice functions from other codes. The code has been benchmarked against results from other codes for the ATF*** that use this approximation or do the calculation in a different way. The new code has been used to calculate the emittance growth due to intrabeam scattering for the lattices currently proposed for the ILC Damping Rings, as IBS is a concern, especially for the electron ring. A description of the code and its user interface, as well as results for the Damping Rings, will be presented.
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*K. Bane, in Proceedings of EPAC2002, p.1443. **A. Terebilo, Accelerator Toolbox for MATLAB, SLAC-PUB-8732 and www-ssrl.slac.stanford.edu/at/. ***K. Kubo et al. PhysRevST AB.8.081001 (2005). |
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WEPCH167 | Study of Scatterer Method to Compensate Asymmetric Distribution of Slowly Extracted Beam at HIMAC Synchrotron | scattering, simulation, extraction, synchrotron | 2322 | ||||
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In the medical use of the ion beam, the following characteristics of the beam are preferred: 1) Symmetric Gaussian beam profile is convenient for the scanning irradiation. 2) In the rotating gantry system, the symmetric beam condition can realize no-correlation between the beam profiles and the rotation angles of the gantry. However, the slowly extracted beam has asymmetric distribution in the phase-space and a difference between the horizontal emittance and vertical one. Thus, we have proposed the thin scatterer method to compensate the phase-space distribution of the slowly extracted beam, although the emittance is enlarged by scattering. As a result of particle tracking and experiment, it was verified that the asymmetric distribution was compensated by very small scattering angle. It was also simulated that this scatterer method can realize the symmetric beam condition for the rotating gantry. In this paper, these results of asymmetry compensation for the slow-extraction at HIMAC is presented.
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WEPCH168 | Development toward Turn-key Beam Delivery for Therapeutic Operation at HIMAC | extraction, ion, heavy-ion, quadrupole | 2325 | ||||
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Since 1994, more than 2500 cancer patients have been treated by carbon ion beam at HIMAC. To increase the number of patients per day, we have studied the reproducibility of the beam quality, such as the position, profile and intensity, during the operation. For this purpose, the accelerator needs high reproducibility to minimize the beam tuning time with more flexible scheme. Further, the irradiation system and the accelerator need to ensure dose uniformity. As a result of this study, it was found that a slight change of the magnetic field in the transport line would not affect the beam quality. However, a slight change of the horizontal tune strongly affects the beam quality because of a resonant slow-extraction. In this paper, we report about our investigation and present result of the development.
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WEPCH169 | Alternating Phase Focused IH-DTL for Heavy-ion Medical Accelerators | linac, ion, rfq, acceleration | 2328 | ||||
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Tumor therapy using HIMAC has been performed at NIRS since June 1994. With the successful clinical results over more than ten years, a number of projects to construct these complexes have been proposed over the world. Since existing heavy-ion linacs are large in size, the development of compact linacs would play a key role in designing compact and cost-effective complexes. Therefore, we developed an injector system consisting of RFQ and Interdigital H-mode (IH) DTL having the frequency of 200 MHz. The injector system can accelerate carbon ions up to 4.0 AMeV. For the beam focusing of IH-DTL, the method of Alternating Phase Focusing (APF) was employed. With the IH structure and rather high frequency, the cavity size is compact; the radius is 0.4 m, and lengths of RFQ and IH-DTL are 2.5m and 3.5m respectively. The fabrication of RFQ was completed, and we succeeded to accelerate carbon ions with satisfactory performances. For IH-DTL, the full-scale model was first fabricated. With the encouraging result* of its electric field measurement, we constructed IH-DTL and beam acceleration tests will be performed in March 2006. We will present the performances of the entire injector system.
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*Y. Iwata et al., Nucl Instr. & Meth in Phys. Res. A (submitted). |
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WEPCH188 | Compact Picosecond Pulse Radiolysis System Using Photo-cathode RF Gun | laser, electron, injection, gun | 2373 | ||||
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A very compact picosecond pulse radiolysis system has been installed and operated at Waseda University. The system is composed of a laser photo-cathode RF gun as the pump source and stable Nd:YLF laser as the white light source to probe the reaction in the picosecond region. The white light generation is performed by the non-linear effect of intense laser light with the wavelength of 1047 nm into the water cell. The experimental results with the time resolution of 18 ps by examining the time profile of hydrated electron have been obtained. The system configuration will be also presented at the conference.
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WEPLS002 | Design and Expected Performance of the Muon Beamline for the Muon Ionisation Cooling Experiment | target, proton, simulation, extraction | 2397 | ||||
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It is proposed to install a Muon Ionisation Cooling Experiment (MICE) at the ISIS facility, at Rutherford Appleton Laboratory (RAL). This experiment will be the first demonstration of ionisation cooling as a means to reduce the large transverse emittance of the muon beam, produced during the early stages of a Neutrino Factory. In order to permit a realistic demonstration of cooling, a beam of muons must be produced, possessing particular qualities, notably in emittance and momenta. This paper describes the current design for the muon beamline, outlining issues particular to the needs of the MICE experiment, and discusses its expected performance.
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WEPLS003 | Simulation of MICE Using G4MICE | simulation, factory, quadrupole, coupling | 2400 | ||||
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In the Muon Ionisation Cooling Experiment (MICE), muons will be fired one by one through one or two cooling cells. The experiment will be used to optimise simulation of an ionisation cooling channel for a future Neutrino Factory. This is achieved by measuring the position of each muon in six-dimensional phase space and examining the behaviour of muons collected into bunches offline. The experiment will be run with a number of different input beams, magnet configurations, RF configurations and absorber types. We present the simulated detector and cooling performance of the MICE cooling channel using the G4MICE simulation code for a range of configurations. We detail the simulation of engineering, field and detector models and examine the implications for the cooling efficacy and measurement.
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WEPLS007 | A Six-dimensional Muon Beam Cooling Experiment | dipole, collider, simulation, beam-cooling | 2409 | ||||
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Ionization cooling, a method for shrinking the size of a particle beam, is an essential technique for the use of muons in future particle accelerators. Muon colliders and neutrino factories, examples of such future accelerators, depend on the development of robust and affordable ionization cooling technologies. A 6D cooling experiment has been proposed, incorporating a novel configuration of helical and solenoidal magnets in a prototype cooling channel. This Helical Cooling Channel (HCC) experiment is being designed with simulations and prototypes to provide an affordable and striking demonstration that 6D muon beam cooling is understood well enough to enable intense neutrino factories and high-luminosity muon colliders. Because of the large amount of expected beam cooling, helium instead of hydrogen can be used for the initial experiment, avoiding the safety complications of hydrogen. Cryostats are currently being developed using internal heat exchangers for simple, effective and safe hydrogen absorber systems to use in later cooling experiments and real cooling channels. The experimental design choices and corresponding numerical simulations are reviewed.
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WEPLS009 | Summary of the Low Emittance Muon Collider Workshop (February 6-10, 2006) | collider, proton, target, luminosity | 2412 | ||||
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The Low Emittance Muon Collider workshop, held at Fermilab February 6-10, 2006 focused on the development of high-luminosity muon colliders using extreme muon beam cooling, where many constraints on muon collider designs are alleviated with beams of smaller emittance and lower intensity. The workshop covered topics related to proton drivers, targetry, muon capture, bunching, cooling, cooling demonstration experiments, bunch recombination, muon acceleration, collider lattices, interaction-point design, site boundary radiation, and detector concepts for energy frontier and Higgs particle studies. Lower emittance allows for a reduction in the required muon current for a given luminosity and also allows high energy to be attained by recirculating the beam through high frequency ILC RF cavities. The highlights of the workshop and the prospects for such colliders will be discussed.
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WEPLS012 | Use of Gas-filled Cavities in Muon Capture for a Muon Collider or Neutrino Factory | factory, target, collider, focusing | 2421 | ||||
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Recent studies indicate that gas-filled cavities can provide high-gradient acceleration and simultaneous cooling for muons. In this paper we explore using these cavities in the front-end of the capture and cooling systems for muon colliders and neutrino factories. For a muon collider scenario we consider capturing the beam in a low-frequency cavity (~50 MHz) and cooling immediate after capture. For a neutrino factory, we consider capturing beam in high-frequency buckets and phase-energy rotating and cooling them using gas-filled rf cavities. Scenario variants are described and studied.
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WEPLS016 | Studies of a Gas-filled Helical Muon Beam Cooling Channel | simulation, dipole, sextupole, quadrupole | 2424 | ||||
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A helical cooling channel (HCC) can quickly reduce the six dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of solenoidal, helical dipole, and helical quadrupole magnetic fields to provide the focusing and dispersion needed for emittance exchange as the beam follows an equilibrium helical orbit through a continuous homogeneous absorber. We consider liquid helium and liquid hydrogen absorbers in HCC segments that alternate with RF accelerating sections and we also consider gaseous hydrogen absorber in pressurized RF cavities imbedded in HCC segments. In the case of liquid absorber, the possibility of using superconducting RF in low magnetic field regions between the HCC segments may provide a cost effective solution to the high repetition rate needed for an intense neutrino factory or high average luminosity muon collider. In the gaseous hydrogen absorber case, the pressurized RF cavities can be operated at low temperature to improve their efficiency for higher repetition rates. Numerical simulations are used to optimize and compare the liquid and gaseous HCC techniques.
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WEPLS018 | Optics for Phase Ionization Cooling of Muon Beams | focusing, collider, resonance, space-charge | 2430 | ||||
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The realization of a muon collider requires a reduction of the 6D normalized emittance of an initially generated muon beam by a factor of more than 106. Analytical and simulation studies of 6D muon beam ionization cooling in a helical channel filled with pressurized gas or liquid hydrogen absorber indicate that a factor of 106 is possible. Further reduction of the normalized 4D transverse emittance by an additional two orders of magnitude is envisioned using Parametric-resonance Ionization Cooling (PIC). To realize the phase shrinkage effect in the parametric resonance method, one needs to design a focusing channel free of chromatic and spherical aberrations. We report results of our study of a concept of an aberration-free wiggler transport line with an alternating dispersion function. Resonant beam focusing at thin beryllium wedge absorber plates positioned near zero dispersion points then provides the predicted PIC effect.
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WEPLS019 | Parameters for Absorber-based Reverse Emittance Exchange of Muon Beams | collider, acceleration, betatron, scattering | 2433 | ||||
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The normalized longitudinal emittance of a muon beam after six-dimensional ionization cooling appears very small compared to the value that could be utilized or maintained after acceleration to muon collider energy. This circumstance offers the possibility for further reduction of the transverse emittance by introducing absorber-based reverse emittance exchange (REMEX) between longitudinal and transverse degrees of freedom before acceleration to high energy. REMEX follows Parametric-resonance Ionization Cooling and is accomplished in two stages. In the first stage the beam is stretched to fill the RF bucket at the initial cooling energy. In the second stage the beam is accelerated to about 2.5 GeV, where energy straggling begins to limit the absorber technique, and stretched again. The potential transverse emittance reduction and the intrinsic limitations of the REMEX technique have been analyzed earlier. In this report, we describe the required beam transport and RF parameters needed to achieve the maximum REMEX effect.
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WEPLS021 | The PLASMONX Project for Advanced Beam Physics Experiments | laser, electron, photon, vacuum | 2439 | ||||
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The Project PLASMONX is well progressing into its design phase and has entered as well its second phase of procurements for main components. The project foresees the installation at LNF of a Ti:Sa laser system (peak power > 170 TW), synchronized to the high brightness electron beam produced by the SPARC photo-injector. The advancement of the procurement of such a laser system is reported, as well as the construction plans of a new building at LNF to host a dedicated laboratory for high intensity photon beam experiments (High Intensity Laser Laboratory). Several experiments are foreseen using this complex facility, mainly in the high gradient plasma acceleration field and in the field of mono-chromatic ultra-fast X-ray pulse generation via Thomson back-scattering. We present an innovative scheme of external injection of the SPARC beam into laser wake-field driven plasma waves. Detailed numerical simulations have been carried out to study the generation of short electron bunches, to be injected into plasma waves driven with adiabatically variable density in order to compress the bunch at injection and further accelerate it by preserving a small energy spread and good beam quality.
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WEPLS044 | Design of a Superconducting Cavity for a SRF Injector | gun, laser, cathode, electron | 2472 | ||||
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In a collaboration between BESSY, DESY, FZR, MBI and BINP a 3-1/2 cell superconducting RF electron gun is under development at the FZ - Rossendorf. The status of the project and the progress obtained in the last year is reported on this conference. The motivation for the design of a new gun cavity, presented in this paper, is the new FEL project at BESSY. This FEL is designed for a bunch charge of 2.5 nC and the transverse emittance should be comparable with that of the current SRF gun project. In order to compensate the high bunch charge a high electric field on the cavity axis is necessary. In the present paper we will present the design of a 1-1/2 cell cavity for a superconducting RF gun. The active length of the cavity (without beam tube) is 14.4 cm. For the magnetic peak field the conservative value of 130 mT is assumed. The obtained particle energy is 6.6 MeV, corresponding to an accelerating field strength of 45.6 MV/m . In the TESLA cavity the same magnetic peak field is connected with an accelerating field strength of approximately 31 MV/m. Tracking calculation of electron bunches are in progress and will be also reported.
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WEPLS047 | 3-1/2 Cell Superconducting RF Gun Simulations | gun, cathode, simulation, focusing | 2481 | ||||
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A 3-1/2 cell superconducting RF photocathode gun is being developed at Forschungszentrum Rossendorf to produce a high peak current, low emittance electron beam. This technology is essential to the realisation of many large scale facilities. The gun is designed for CW operation mode with 1 mA current and 9.5 MeV electron energy, and it will be installed at the ELBE superconducting electron linear accelerator. The gun will have a 3-1/2 cell niobium cavity operating at 1.3 GHz. The cavity consists of three cells with TESLA geometry and a specially designed half-cell in which the photocathode will be placed. Typical ERL-based projects require ~100 mA average current, and therefore suitable upgrade paths are required. Simulations have been carried out to evaluate the design and to determine suitable upgrades for higher current operation. Simulations of alternative cathode surface shapes are presented. Several couplers have been identified that can provide higher power to the cavity, whose integration and suitability has been verified. All the investigations that have identified possible solutions to higher current operation are discussed in this report.
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WEPLS049 | The Design of a Hybrid Photoinjector for High Brightness Beam Applications | gun, simulation, coupling, bunching | 2487 | ||||
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In this paper, we illustrate the electromagnetic and beam dynamics design procedure of a new class of photoinjector, a hybrid standing/traveling wave structure. In this device a standing wave RF gun section is integrated with a downstream traveling wave structure through a coupling cell that feeds simultaneously the two sections. We discuss the advantages in RF and beam performance of the hybrid photoinjector compared to conventional systems. The electromagnetic design has been performed using the 2D and 3D electromagnetic codes Superfish and HFSS. Results of beam dynamics simulations in different operating conditions are also discussed.
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WEPLS055 | Development of Double-decker Electron Beam Accelerator for Femto/attosecond Pulse Radiolysis | electron, gun, linac, laser | 2505 | ||||
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The study of electron-induced reactions in femto/attosecond time region is very important for the next electron beam nanofabrication. Pulse radiolysis with time resolution of sub-picosecond, as a powerful method to study such reactions in materials, has been developed by using radio-frequency electron accelerators and ultrashort lasers. In Osaka University, a new concept of double-decker electron beam accelerator is proposed for opening next pulse radiolysis on femto/attosecond time scale. The double electron beams with time delay of 1.4ns (350ps x 4) and bunch charge of 0.5-0.6 nC were generated in a photocathode electron accelerator by injecting two laser pulses into the photocathode. The beam energy of the two beams was 31.7MeV. The transverse normalized emittance was 3~6 mm-mrad for both the beams. The front of them is converted to Cherenkov light and used as a probe light source, and the back is used as a pump source. Both electron pulses are generated by one accelerator, resulting in no time jitter between the pump electron bunch and the probe laser pulse.
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WEPLS058 | Femtosecond Single-bunch Electron Linear Accelerator Based on a Photocathode RF Gun | electron, gun, linac, laser | 2514 | ||||
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A femtosecond single-bunch electron linear accelerator based on a photocathode rf gun was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions. A 32 MeV single electron bunch with a bunch length of 98 fs in rms was generated successfully in the linear accelerator with a magnet bunch compressor. The dependences of the bunch length and the transverse emittance on the bunch charge were investigated experimentally and theoretically. The higher-order effects in the magnetic field were studied and compensated successfully by using a nonlinear energy-phase correlation in the bunch produced in the linear accelerator. By using the femtosecond electron bunch, an equivalent velocity spectroscopy with a synchronized femtosecond laser, as a new method with femtosecond time-resolution, was developed for study of the ultrafast reactions or phenomena on the femtosecond time scale.
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WEPLS064 | Wiggler for ILC Cooler | wiggler, quadrupole, focusing, dipole | 2526 | ||||
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We represented the concept of a wiggler with linear piecewise field dependence. This eliminates nonlinearities in wiggler. This type of wiggler can be recommended for usage in ILC cooler.
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WEPLS108 | High Field Solenoid Magnets for Muon Cooling | TESLA, collider, luminosity, scattering | 2634 | ||||
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Magnets made with high-temperature superconducting (HTS) coils operating at low temperatures have the potential to produce extremely high fields for use in beam lines and accelerators. The specific application of interest that we are proposing is to use a very high field (of the order of 50 Tesla) solenoid to provide a very small beta region for the final stages of cooling for a muon collider. With the commercial availability of HTS tape based on BSCCO technology with high current carrying capacity at 4.2 K, very high field solenoid magnets should be possible. In this paper we will evaluate the technical issues associated with building this magnet. In particular we will address how to mitigate the high Lorentz stresses associated with this high field magnet.
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WEPLS114 | Progress on the MICE Tracker Solenoid | vacuum, radiation, power-supply, superconductivity | 2646 | ||||
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This report describes the 400 mm warm bore tracker solenoid for the Muon Ionization Cooling Experiment (MICE). The 2.923 m long tracker solenoid module includes the radiation shutter between the end absorber focus coil modules and the tracker as well as the 2.780 meter long magnet cryostat vacuum vessel. The 2.554 m long tracker solenoid consists of two sections, a three-coil spectrometer magnet and a two-coil matching section that matches the uniform field 4 T spectrometer solenoid into the MICE cooling channel. The two tracker magnets are used to provide a uniform magnetic field for the fiber detectors that are used to measure the muon beam emittance at the two ends of the cooling channel. This paper describes the design for the tracker magnet coils and the 4.2 K cryogenic coolers that are used to cool the superconducting magnet. Interfaces between the magnet and the detectors are discussed.
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THYPA01 | Overview of FEL Injectors | brightness, gun, laser, electron | 2733 | ||||
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Future light sources based on high gain free electron lasers, require the production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake fields effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, hence the photo-injector design and its operation is the leading edge for high quality beam production and for the success of the future light sources. RF guns, photo-cathode materials, laser pulse shaping and synchronization systems are evolving towards a mature technology to produce high quality and stable beams. Nevertheless reduction of thermal emittance, damping of emittance oscillations and bunch compression are still the main issues and challenges for injector designs. With the advent of Energy Recovery Linacs, superconducting RF guns have been also considered in many new projects as a possible electron source operating in CW mode. An overview of recent advancements and future perspectives in FEL injectors will be illustrated in this talk, including a comparison of merits and issues of RF compression versus magnetic compression techniques.
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Transparencies
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THOPA02 | Status of the SCSS Test Accelerator and XFEL Project in Japan | electron, undulator, cathode, radiation | 2741 | ||||
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Construction of the SCSS* 250 MeV test accelerator was completed in October 2005, and the beam commissioning was started in November 2005. The first light at visible wavelength, which is the spontaneous radiation from undulator, was observed right after machine commissioning. We expect the first SASE beam around 60 nm in 2006. The purpose of the test accelerator is to assemble all hardware components in a real machine, and check their performance, reliability and stability. It is also very important to build all control software and link to the main frame to see system performance. All experience will provide feedback to 8 GeV XFEL design, whose construction will start in April 2006.
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*http://www-xfel.spring8.or.jp |
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THOAFI01 | The Development of Computational Tools for Halo Analysis and Study of Halo Growth in the Spallation Neutron Source Linear Accelerator | simulation, quadrupole, linac, CCL | 2768 | ||||
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Computational tools have been developed to quantify the halo in a beam by analyzing beam profiles and identifying the halo particles using the Gaussian area ratio and kurtosis methods. Simulations of various injection quadrupole magnet configurations using three types of initial simulated distributions, along with an analysis of their phase space and rms properties, provides insight into the development of halo in the Spallation Neurton Source linear accelerator. Finally, comparisons with machine beam profile data, taken at the same conditions as that of the simulated data, show how accurately the simulations model the beam and its halo development and provide a better understanding of the best machine configuration with which to minimize beam halo and losses.
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Transparencies
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THOBFI02 | Measurement of the Beam Profiles with the Improved Fresnel Zone Plate Monitor | damping, coupling, wiggler, optics | 2784 | ||||
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We present the recent progress of the FZP (Fresnel Zone Plate) beam profile monitor constructed at KEK-ATF damping ring. This monitor based on an X-ray imaging optics with two FZPs*. In this monitor, the transverse electron beam image at bending magnet is twenty-times magnified by the two FZPs and detected on an X-ray CCD camera. Then the real-time and 2-dimentional transverse beam profiles can be obtained with non-destructive manner by using this monitor. The expected spatial resolution is less than 1 micro-meter. Recently, we install the new mechanical shutter to improve time resolution of the monitor and avoid the effects of the short-term movement of the beam or the monitor itself. By applying this shutter, the shutter opening time was reduced less than 1ms and the beam profile could be measured more accurately. In this paper, we report the new shutter performance and the measurement results of beam profiles by the improved FZP beam profile monitor.
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*K. Iida, et al. Nucl. Instrum. Meth. A 506 (2003) 41-49. |
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Transparencies
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THPCH006 | Scaling Laws for the Montague Resonance | resonance, simulation, synchrotron, coupling | 2796 | ||||
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The space-charge-driven Montague resonance is a source of emittance coupling in high-intensity accelerators with un-split tunes. Here we present scaling laws for the stop-band widths, growth rates and crossing behavior of this fourth order resonance. Our results on the coupling can be applied to circular machines as well as to linear accelerators. Based on self-consistent coasting beam simulation we show that for slow crossing of the stop-bands a strong directional dependence exists: in one direction the exchange is smooth and reversible, in the other direction it is discontinuous. We also discuss the combined effect of the Montague resonance and linear coupling by skew quadrupoles.
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THPCH007 | Development of a High Current Proton Linac for FRANZ | rfq, proton, beam-losses, bunching | 2799 | ||||
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The FRANZ Facility, a planned worldwide unique pulsed neutron source, will be built at Frankfurt University. A single RFQ or an RFQ-IH combination working at 175MHz will be used to accelerate a 200mA proton beam to the energy which can meet the demands of required neutron production. The beam dynamics study has been performed to design a flexible, short-structure and low-beam-loss RFQ accelerator. The design results and relative analyses are presented.
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THPCH010 | Electron Beam-laser Interaction near the Cathode in a High Brightness Photoinjector | laser, electron, cathode, space-charge | 2805 | ||||
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The production of high charge short bunches in a high brightness photoinjector requires laser pulses driving the cathode with GW range peak power on a mm spot size. The resulting transverse electric field experienced by the electron beam near the cathode is of the order of 200-500 MV/m, well in excess of a typical RF accelerating field of 50-100 MV/m. We present here an analytical and computational study of the resultant beam dynamics. Simulations including the electron beam-laser interaction have been performed with the code HOMDYN taking into account the superposition of incident and reflected laser pulses as well as space charge fields. Under this conditions the emittance degradation is negligible, as predicted by analytical methods, but a longitudinal charge modulation occurs on the scale of the laser wavelength, in case of oblique incidence, driven by the longitudinal component of the laser field. Preliminary simulations up to the photoinjector exit show that charge modulation is transformed into energy modulation via the space charge field, which may produce enhanced microbunching effects when the beam is further compressed in a magnetic chicane.
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THPCH013 | Study of Particle Losses Mechanism for J-PARC Main Ring | resonance, injection, space-charge, sextupole | 2811 | ||||
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Detailed understanding as well as confidence in simulation modeling of long-term effects (~ 100'000 turns) of high intensity proton beam is crucial for Main Ring (MR) of the J-PARC project, where it is necessary to hold the high-intensity beam over typically ~ 2 sec with a loss level less than 1%. The major focus of such study is the combined effect of space charge and nonlinear resonances and its impact on halo formation and/or beam loss. In frame of this report, the tracking results for the injection process including realistic representation of the ring's focusing structure are discussed. Optimization of the working point during the injection process is presented. The halo formation and particle losses during the injection and acceleration for MR have been estimated for realistic magnetic field errors.
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THPCH015 | Matched and Equipartitioned Method for High-intensity RFQ Accelerators | rfq, resonance, linac, space-charge | 2814 | ||||
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Maintaining beam envelope match, avoiding structure resonances, and using an equilibrium (equipartitioned) energy balance within the beam are the primary methods for preventing emittance growth and halo formation in high current linacs. A design strategy that requires the RFQ accelerator to be matched and equipartitioned over most of its length will produces very robust designs under a wide variety of conditions, the beam with proper energy balance is also inherently stable against resonances near the operation point. Based on this strategy, a new dynamics method is proposed to avoid the envelope mismatch and energy imbalance between different degrees of freedom. The beam sizes are well confined to match the accelerating channel in this method, to minimize the emittance growth and the related beam loss. Following the method, a RFQ design code named MATCHDESIGN has been written at Peking University. A test design of 50mA proton RFQ operating at 350 MHz was given to prove this method and it resulted in a good dynamics design.
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THPCH018 | Resonance Trapping, Halo Formation and Incoherent Emittance Growth due to Electron Cloud | electron, simulation, resonance, LHC | 2820 | ||||
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The pinched electron cloud introduces a tune shift along the bunch, which together with synchrotron motion, leads to a periodic crossing of resonances. The resonances are excited by the longitudinal distribution of the electron cloud around the storage ring. We benchmark the PIC code HEADTAIL against a simplified weak-strong tracking code based on an analytical field model, obtaining an excellent agreement. The simplified code is then used for exploring the long term evolution of the beam emittance, and for studying more realistic lattice models. Results are presented for the CERN SPS and the LHC.
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THPCH023 | Vlasov Equilibrium of a Periodically Twisted Ellipse-shaped Charged-particle Beam in a Non-axisymmetric Periodic Magnetic Focusing Field | focusing, plasma, klystron, permanent-magnet | 2826 | ||||
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A new Vlasov equilibrium is obtained for a periodically twisted ellipse-shaped charged-particle beam in a non-axisymmetric periodic permanent magnetic focusing field. The equilibrium distribution function is derived, and the statistical properties of the beam equilibrium are studied. The generalized envelope equations derived from the kinetic theory recovers the generalized envelope equations obtained in the cold-fluid theory when the temperature is taken to be zero*. Examples of periodically twisted elliptic beam equilibrium are presented and applications are explored.
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*J. Zhou et al. Exact Paraxial Cold-Fluid Equilibrium of a High-Intensity Periodically Twisted Ellipse-Shaped Charged-Particle Beam, Phys. Rev. ST Accel. Beams, submitted for publication (2005). |
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THPCH037 | Wakefields Effects of New ILC Cavity Shapes | linac, TESLA, simulation, DESY | 2862 | ||||
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The operation of International Linear Collider (ILC) requires high gradients and quality factors in accelerating structure. One way to reach it is to modify the cavity shape to reduce the ratio of peak surface magnetic to accelerating field. Two candidate shapes are suggested recently: the Re-entrant shape and the Low-Loss shape. In this paper we estimate numerically longitudinal and transverse short range wake functions for the new shapes. The obtained analytical expressions are used in beam dynamic simulations for ILC lattice. We show that ILC will tolerate the cavities with the new shape and the smaller iris diameter.
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THPCH044 | Beam Break-up Instability in the FERMI@ELETTRA Linac | linac, BBU, FEL, simulation | 2883 | ||||
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The beam break-up instability is studied for the 1.2 GeV linac of FERMI @ ELETTRA FEL*. This instability is driven by transverse wake fields acting on an electron beam travelling off-axis in the accelerating structures due to the launching errors in positions, angles, energy and misalignment of various lattice elements. Two operational scenarios are considered: one with a relatively long electron bunch of 1.5 ps and a moderate peak current of 500 A and one with a shorter bunch of 0.7 ps and a higher peak current of 800 A. Attention is given to the correction of the "banana" shape of the electron bunch caused by the instability. The simulation results are compared with the analytical predictions.
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*C. Bocchetta et al. FERMI@Elettra Conceptual Design for a Seeded Harmonic Cascade FEL for EUV and Soft X-rays, this conference. |
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THPCH048 | Transverse Coupled Bunch Instability Driven by 792-MHz Cavity HOM in NewSUBARU Electron Storage Ring | damping, synchrotron, pick-up, betatron | 2892 | ||||
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The 792-MHz HOM of the RF cavity can drive horizontal coupled bunch instability in the NewSUBARU electron storage ring. This instability is now avoided by tuning the HOM frequency with an additional tuner (HOM tuner). Detailed characteristics of this instability were investigated by changing the HOM frequency, betatron tune, chromaticity and magnitude of the stored current at the energy of 1 GeV. The experiments were performed with 6-bunch equi-space filling to clarify the mode number. Bunch oscillations show saw-tooth patterns when the stored current is not so large. The measured results are compared with an analytical calculation using a rigid bunch model and Sacherer's formalism. The fundamental aspects can be well explained by the calculation, but there exist many problems that cannot be explained by the rigid bunch model.
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THPCH054 | SIMPSONS with Wake Field Effects | kicker, extraction, injection, impedance | 2910 | ||||
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Simpsons, which is originally developed by S. Machida, is the program which calculates the space charge effect to the beam in the ring. The wake field effect to the beam is also installed in this program, because the emittance growth not only due to the space charge effect, but also due to the wake field effect is the important issue. The results of the simulation in J-PARC case are also represented.
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THPCH057 | The Fast Vertical Single-bunch Instability after Injection into the CERN Super Proton Synchrotron | impedance, SPS, simulation, LHC | 2913 | ||||
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Since 2003, high-intensity single-bunch proton beams with low longitudinal emittance have been affected by heavy losses after less than one synchrotron period after injection. The effects of the resonance frequency of the responsible impedance, longitudinal emittance and chromaticity on the intensity threshold were already discussed in detail in 2004, comparing analytical predictions with simulation results. In this paper the evolution of the instability between injection and the time of beam loss is our main concern. Measurements are compared with HEADTAIL simulations. A travelling-wave pattern propagating along the bunch, which is the signature of a Beam Break-Up or Transverse Mode Coupling Instability (TMCI), is clearly identified. The oscillating frequency, near ~1 GHz, is in good agreement with the usual broad-band impedance model deduced from beam-based measurements like the head-tail growth rate vs. chromaticity.
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THPCH061 | Tune Shift Induced by Nonlinear Resistive Wall Wake Field of Flat Collimator | impedance, SPS, CERN, LHC | 2925 | ||||
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We present formulae for the coherent and incoherent tune shifts due to the nonlinear resistive wall wake field for a single beam traveling between two parallel plates. In particular, we demonstrate that the nonlinear terms of the resistive wall wake field become important if the gap between the plates is comparable to the transverse rms beam size. We also compare the theoretically predicted tune shift as a function of gap size with measurements for an LHC prototype graphite collimator in the CERN SPS and with simulations.
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THPCH151 | Commissioning of the Laser System for SPARC Photoinjector | laser, cathode, simulation, gun | 3146 | ||||
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In this paper we report the commissioning of the SPARC photoinjector laser system. In the high brightness photoinjector the quality of the electron beam is directly related to the features of the laser pulse. In fact the temporal pulse shape, the temporization and the transverse distribution of the electron beam is determined by the incoming laser pulse. The SPARC laser system is based on an amplified Ti:Sapphire active medium and the pulse shape is imposed by a programmable acousto-optics dispersive filter. The transfer-line has been designed to reduce the angular jitter and to preserve to the cathode the temporal and spatial features of the laser pulse. The laser system has been integrated with the accelerator apparatus. The diagnostics and the control system has been completed. We present the measured performances and the simulations we carried out.
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THPCH153 | Production of Temporally Flat Top UV Laser Pulses for SPARC Photoinjector | laser, target, diagnostics, electron | 3152 | ||||
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In the SPARC photoinjector, the amplified Ti:Sa laser system is conceived to produce an UV flat top pulse profile required to reduce the beam emittance by minimizing the non-linear space charge effects in the photoelectrons pulse. Beam dynamic simulations indicate that the optimal pulse distribution must be flat top in space and time with 10 ps FWHM duration, 1 ps of rise and fall time and a limited ripple on the plateau. In a previous work~\cite{loose} it was demonstrated the possibility to use a programmable dispersive acousto-optics (AO) filter to achieve pulse profile close to the optimal one. In this paper we report the characterization of the effects of harmonics conversion on the pulse temporal profile. A technique to overcome the harmonics conversion distortions on the laser pulses at the fundamental wavelength in order to obtain the target pulse profile is explained too. Measurements and simulations in the temporal and spectral domain at the fundamental laser wavelength and at the second and third harmonics are presented in order to validate our work. It is also described a time diagnostic device for the UV pulses.
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*H. Loos et al. "Temporal E-Beam Shaping in an S-Band Accelerator", Proc. Particle Accelerator Conference, p.642, 2005, Knoxville, TN, USA. |
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THPCH164 | Progress and Status of the MICE Project | coupling, optics, quadrupole, alignment | 3176 | ||||
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The design of a Neutrino Factory (NF) has been the subject of several physics studies. For a NF based on a stored high energy muon beam, a potential key technology that has a significant impact on its cost and practicality is the ability to cool rapidly the muon beam prior to acceleration. The muon ionisation cooling experiment (MICE), currently being constructed at the Rutherford Appleton Laboratory (UK), is a demonstration of emittance cooling in a linear cooling channel. A new muon beam line and the basic infrastructure for MICE are funded, and a muon beam is under construction with an expected availability in spring 2007. The experiment will be methodically assembled over the following few years to bring the beam through RF accelerating cavities and liquid hydrogen absorbers and confined by a solenoidal magnetic field. The emittance of the beam before and after the cooling channel is measured in tracking spectrometers. The current status of the beam line and infrastructure build and of the components of MICE is presented.
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THPCH167 | Commissioning of the Diamond Pre-injector Linac | linac, dipole, single-bunch, DIAMOND | 3185 | ||||
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Commissioning of the linac for the Diamond Light Source (DLS) was completed in October 2005. The linac was supplied by Accel Instruments as a complete system, with DLS providing beam diagnostics, beam analysis software, control system hardware and standard vacuum components. Much of the beam analysis was carried out using the first part of the Linac to Booster transfer line (LTB), which was designed and built by DLS. Operation of the linac and LTB at 100 MeV in long-pulse and short-pulse modes of operation was demonstrated, and all operational parameters were measured to be within specification.
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THPLS004 | Canadian Light Source Update | coupling, undulator, lattice, electron | 3269 | ||||
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The Canadian Light Source (CLS) storage ring has been operating routinely since commissioning was completed in the spring of 2004. Beam currents up to 230 mA have been achieved with the single superconducting RF cavity. With steady improvement beam lifetimes (1/e) of 10 hours at 170 mA and 0.25% coupling are now possible. In the last year the vertical tune was increased by 1 integer to produce a smaller vertical beam size in the ID straight sections. This year the horizontal tune will be increased to reduce the beam emittance. The vertical coupling has been reduced both globally and locally using a skew quadrupole response technique. A wide range of photons energies are provided by an initial complement of five insertion devices (IDs) and and two infrared (IR) ports. The 5 m straights have room for two IDs. The light cones from these IDs are separated by about 1.5 mrad by "chicaning" the electron beam in the straights. To date two IDs have been installed in one straight using the chicaning technique. As well, a superconducting wiggler and a in-vacuum undulator have been installed and commissioned. An AppleII type elliptically polarizing undulator will be installed in April 2006.
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THPLS005 | Commissioning Results from the Injection System for the Australian Synchrotron Project | injection, booster, synchrotron, quadrupole | 3272 | ||||
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Danfysik has built a full-energy turnkey injection system for the Australian Synchrotron. The system consists of a 100 MeV LINAC, a low-energy transfer beamline, a full-energy booster and a high energy transfer beamline. The booster synchrotron will deliver a 3-GeV beam with an emittance of 33 nm. The lattice is designed to have many cells with combined-function magnets (dipole, quadrupole and sextupole fields) in order to reach this very small emittance. The current in single- and multi-bunch mode will be in excess of 0.5 and 5 mA, respectively. The repetition frequency will be 1 Hz. At the time of writing this abstract, the LINAC beam has been injected into the low-energy transfer beamline. The project is on schedule for delivery in April 2006. Results from the commissioning of the system will be presented together with its performance.
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THPLS008 | Commissioning of the SOLEIL Booster | booster, injection, SOLEIL, extraction | 3281 | ||||
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SOLEIL is a 2.75 GeV new third generation synchrotron radiation facility under construction near Paris. The injector system is composed of a 100 MeV electron Linac pre-accelerator followed by a full energy (2.75 GeV) booster synchrotron. The booster lattice is based on a FODO structure with missing magnet. With a circumference of 157 m and low field magnets (0.74 T), the emittance is in the range of 110 to 150 nm.rad at 2.75 GeV. The magnets are excited at 3 Hz, using switched mode power supplies, with digital regulation. The LEP type RF cavity is powered by a 35 kW-352 MHz solid state amplifier. Closed orbits are measured turn by turn, using the BPM Libera digital electronics. The commissioning took place in October 2005, and an acceleration efficiency of 75% was obtained at the maximum energy. The main results achieved during that commissioning will be reported.
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THPLS010 | Metrology for the Beam Emittance Measurement of the SOLEIL Injector | booster, linac, quadrupole, SOLEIL | 3287 | ||||
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The injector system of SOLEIL is composed of a 100 MeV electron linac pre-accelerator followed by a full energy 2.75 GeV booster synchrotron, operating at 3 Hz. Dedicated diagnostics such as emittance monitors are installed on the two transfer lines between the linac and the booster and between the booster and the storage ring. The measurement is performed using the gradient method, relying on YAG screens and high resolution CCD cameras. This paper will show the metrology of the emittance measurements which were made for the HELIOS (THALES) iinac beam (total emittance in the range of 1 μm.rad) and for the booster beam (rms emittance ~ 150 nm.rad): error sources are identified and specific corrections are shown. Additional analysis of the dynamics of the injection into the booster and into the storage ring is made for a deeper characterization.
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THPLS020 | Progress Report on PETRA III | PETRA, wiggler, DESY, vacuum | 3317 | ||||
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Starting from the middle of 2007, the existing storage ring PETRA II at DESY will be converted into the hard x-ray light source PETRA III. The project was launched in 2002, and in preparation of the conversion a technical design report was published in 2004. Since then detailed design and construction of technical components have begun. Prototypes have been built and tested and the procurement of major parts of the machine components such as magnets and vacuum chambers has started. The project is well underway and in line with the goal of starting the rebuilding in 2007 and the commissioning in 2009. In addition to an overall status report, the development of components and measurement results of prototypes will be presented.
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THPLS022 | Radiation Dose Related to ANKA Operation Mode | radiation, storage-ring, optics, injection | 3323 | ||||
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Radiation doses in the ANKA hall are measured by area monitoring and Albedo dosimeters. In August 2004 the machine optics was replaced by a new optics with reduced emittance and higher brightness. Measurements of the beam lifetime and the related radiation doses show a strong correlation between the operation mode of the machine and the dose distribution in the hall.
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THPLS034 | Top-up Operation of SPring-8 Storage Ring with Low Emittance Optics | optics, injection, electron, brilliance | 3359 | ||||
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We have succeeded in providing stable and three-times more brilliant x-ray to users by combining top-up operation with low emittance optics. The optics with the low emittance of 3nmrad was first applied to the user operation in November 2002. Although the low emittance provided the brilliant x-ray, the extremely short beam lifetime much disturbed the precise experiments. Moreover, the aborted electron beam damaged the part of vacuum chamber at the beam injection section. The low emittance operation was thus suspended in October 2003. By improving design of the vacuum chamber and introducing the top-up injection, the problems for the stable operation were resolved, and then the top-up operation with the low emittance optics has been first achieved at SPring-8. This paper illustrates how we achieved this sophisticated operation by explaining the following three essential investigations: (1) reduction of natural emittance for a storage ring with four magnet-free long straight sections, (2) protection of vacuum chamber from aborted electron beam, and (3) consistency to the top-up operation. The obtained performance is also described in the paper.
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THPLS035 | Next Generation Light Source Storage Ring at SPring-8 | storage-ring, dynamic-aperture, sextupole, coupling | 3362 | ||||
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A linac-based XFEL and an ERL are widely accepted as next-generation light sources. But they still have many technologically difficult problems to overcome. In contrast, electron beams in a storage ring are very stable. Thus, we examined the possibility of the storage ring as a next-generation light source. We designed a storage ring with an energy of 6 GeV and a circumference of 1436 m. The ring consists of 24 ten-bend achromat cells and has a natural emittance of 83 pm·rad. The circumference is equal to that of SPring-8 storage ring and the cell length is two times, which enables us to replace the existing storage ring with this new one in the SPring-8 tunnel and use the photon beam-lines without constructing new ones. Particle tracking simulation showed that the horizontal dynamic aperture at the center of a straight section is -3.7 mm and +3.4 mm and that it can be increased to -6.6 mm and +10.0 mm by changing the sextupole strength for chromaticity correction while keeping zero chromaticity. In this paper, we describe the design and the dynamic aperture of the extremely low emittance storage ring at SPring-8.
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THPLS040 | Present Status of the UVSOR-II | electron, laser, undulator, FEL | 3374 | ||||
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UVSOR electron storage ring, which was a 2nd-generation synchrotron radiation (SR) light source for VUV and soft x-ray region, has been renewed as UVSOR-II at the beginning of 2003. Because of the improvement, the beam emittance has been reduced from 165nm-rad to 27nm-rad, and longer straight sections with smaller vertical betatron functions have been provided. In addition to a helical/linear undulator, two in-vacuum undulators have been installed in the long straight sections at the improvement. New variably polarized undulator will be also installed in summer 2006. Improvement of booster synchrotron will be also performed in summer 2006 with aiming to top-up operation in the future. Now UVSOR-II has been operated in 750MeV with the emittance of 27nm-rad in daily users runs. Not only the development of high quality SR beams but also basic investigations for new light source have been performed; development of storage ring FEL and investigation of intense THz burst SR. Bunch slicing experiment with a Ti:Sa laser (800nm) has also been started since 2005, and experiments for coherent harmonic generation and coherent SR generation with the laser-beam interaction have been performed.
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THPLS060 | Lifetime and Acceptance at the SLS | scattering, coupling, SLS, resonance | 3421 | ||||
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Beam lifetime at the storage ring of the Swiss Light Source (SLS) is limited by Touschek effect and elastic gas scattering. Both mechanism are affected by narrow gaps in the machine, elastic scattering directly by the vertical acceptance limitation, Touschek scattering via a possible restriction of lattice momentum acceptance due to coupling. The particle loss mechanism was explored by evaluations of lifetime as function of scraper position, chromaticity and emittance coupling.
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THPLS067 | Vertical Beam Size Control in TLS and TPS | coupling, feedback, quadrupole, betatron | 3442 | ||||
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Vertical beam size control is an important issue in the light source operations. The horizontal-vertical betatron coupling and vertical dispersion were measured and corrected to small values in the TLS 1.5 GeV storage ring. Estimated beam sizes are compared with the measured values. By employing an effective transverse damping system, the vertical beam blow-up due to transverse coherent instabilities such as the fast-ion beam instability was suppressed and as a result, the light source is very stable. In NSRRC we are designing an ultra low emittance 3-GeV storage ring and its designed vertical beam size could be as small as a few microns. The ground and mechanic vibration effects, and coherent instabilities could spoil the expected photon brightness due to blow-up of the vertical beam size if not well taken care of. The contributions of these effects to vertical beam size increase will be evaluated and the counter measures to minimize them will be proposed and reported in this paper.
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THPLS068 | Design of Taiwan Future Synchrotron Light Source | dynamic-aperture, coupling, lattice, synchrotron | 3445 | ||||
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We report updated design works for a new 3-3.3 GeV synchrotron light source with a high performance and low emittance storage ring, called Taiwan Photon Source (TPS). With its natural horizontal emittance less than 2 nm-rad and low emittance coupling, TPS will be able to provide an extremely bright photon beam to the demanding users, especially the x-ray community. The lattice type of the TPS is a 24-cell DBA structure and the circumference is 518.4 m. We present the lattice design, the accelerator physics issues and its performances.
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THPLS073 | Effect of Nonlinear Synchrotron Motion on TPS Energy Acceptance | synchrotron, lattice, vacuum, sextupole | 3451 | ||||
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For design of new generation synchrotron light source the first order momentum compaction factor is usually small. The contribution of second order momentum compaction factor can't be neglected. The longitudinal phase space changes significantly due to the nonlinear effect. This will affect the energy acceptance of the particles and reduce the Touschek beam life time. In this paper we analyze the effect of the nonlinear synchrotron motion of TPS lattice design*. The reduction of energy acceptance is estimated. The contribution to second order momentum compaction factor is discussed. Efforts to minimize this nonlinear effect will also be addressed.
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*C. C. Kuo et al., "Design of Taiwan Future Synchrotron Light Source", these proceedings. |
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THPLS074 | Ground Vibration Measurement at NSRRC Site | site, storage-ring, background, simulation | 3454 | ||||
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For the future 3GeV TPS project in the NSRRC, ground vibration would be important for this low emittance machine. We have monitored the ground vibration under various experimental conditions at the NSRRC site. Sensors were installed in the bare site, underground 35 meters deep and ground of TLS storage ring, including an electricity shutdown in the NSRRC. From the collected data, we compare the effect about day and night, traffic effect, internal machine vibration propagation. Specific vibration sources and their propagations are also discussed.
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THPLS088 | Optimizing the Dynamic Aperture for Triple Bend Achromatic Lattices | lattice, quadrupole, dipole, sextupole | 3481 | ||||
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The Triple Bend Achromatic (TBA) lattice has the potential for lower natural emittance per period than the Double Bend Achromatic (DBA) lattice for high brightness light sources. However, the DBA has been chosen for 3rd generation light sources more often due to the higher number of undulator straight section available for a comparable emittance. The TBA has considerable flexibility in linear optics tuning while maintaining this emittance advantage. We have used the tune and chromaticity flexibility of a TBA lattice to minimize the lowest order nonlinearities using a high order achromatic tune condition, while maintaining a constant emittance. This frees the geometric sextupoles to counter the higher order nonlinearities. This procedure is being used to improve the nonlinear dynamics of the TBA as a proposed lattice for the NSLS-II facility. The flexibility of the TBA lattice will also provide for future upgrade capabilities of the beam parameters.
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THPLS089 | Comparison of Double Bend and Triple Bend Achromatic Lattice Structures for NSLS-II | lattice, sextupole, wiggler, dipole | 3484 | ||||
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The Double Bend Achromatic (DBA) and the Triple Bend Achromatic (TBA) lattice have been studied rather extensively for use for the NSLS-II storage ring. The well known advantage of the TBA compared to the DBA is that the emittance per period has the potential to be considerably lower. However, the DBA has been chosen more often due to the greater number of ID straight sections for the users for a desired emittance. We present a comparison of these lattice structures based on the optimization of the non-linear driving terms from the chromatic sextupole and the ease of compensation of these terms using the higher order achromatic cancellation.
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THPLS090 | Consideration of the Double Bend Achromatic Lattice for NSLS-II | lattice, wiggler, insertion, dynamic-aperture | 3487 | ||||
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We present the results of a study of the Double Bend Achromatic (DBA) lattice as a possible choice for the NSLS-II storage ring. The DBA possesses a large number of straight sections with easily tunable beta functions which can be used for insertion device sources and for damping wigglers to reduce emittance. The dispersive regions can be designed to minimize the strength of the chromatic correction sextupoles. A key constraint is the imposition of a limit on circumference which is closely tied to cost. We discuss optimization of the dynamic aperture by minimizing the non-linear driving terms using high-order achromatic cancellation in the non-linear lattice.
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THPLS092 | Nb-Pb Superconducting RF-Gun | dipole, cathode, DESY, laser | 3493 | ||||
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We report on the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead, as compared to other superconducting metals. The concept, mentioned in a previous paper, follows the attractive approach of all niobium superconducting RF-gun as it has been proposed by the BNL group. Measured values of quantum efficiency for lead at various photon energies, analysis of recombination time of photon-broken Cooper pairs for lead and niobium, and preliminary cold test results are discussed in this paper.
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THPLS094 | First Measurement Results at the LEG Project's 100 keV DC Gun Test Stand | gun, diagnostics, cathode, SNR | 3499 | ||||
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The Low Emittance Gun Project (LEG) at PSI aims at developing a high-brightness, high-current electron source: a 20-fold improved brightness compared to present state-of-the-art electron guns. The source is intended to form the basis for a cost-efficient implementation of a high-power X-ray FEL light-source for scientific research at PSI. A field emitter array (FEA) cathode is being considered a source candidate. In order to study pulsed field emission from such a cathode and to investigate space charge compensation techniques as well as to develop diagnostic procedures to characterize the beam resulting from an FEA cathode, a 100 keV DC gun test stand has been built. The test stand gun and diagnostics have been modeled with the codes MAFIA and GPT. From extensive parameter studies an optimized design has been derived and construction of the gun and diagnostics have recently been completed. We report on the commissioning of the test stand and present first measurement results.
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THPLS104 | Optimization Studies of the FERMI@ELETTRA Photoinjector | laser, electron, cathode, gun | 3520 | ||||
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In the framework of the FERMI@ELETTRA project the electron beam characteristics strongly depend from the two operating modes: FEL1 (100nm-40nm) with a photon pulse around 100fs and FEL2 (40nm-10nm) with a long photon pulse (~1ps) having a high resolution spectral bandwidth. We present the multi-particles tracking code results concerning the photoinjector, which includes the RF gun and the first two accelerating sections, describing two possible electron bunch lengths, satisfying the two FEL operation modes. The injector optimization relative to the two options, aimed to produce a very low projected emittance (around 1 mm mrad) with a uniform behavior of the slice parameters (emittance and energy spread) along the bunch, is described in this paper. Moreover sensitivity studies, time and energy jitters estimations are presented for both cases.
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THPLS105 | Characterization of the SPARC Photo-injector with the Movable Emittance Meter | cathode, laser, space-charge, diagnostics | 3523 | ||||
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As a first stage of the commissioning of SPARC accelerator a complete characterization of the photo-injector is planned. The objective is the optimization of the RF-gun setting that best matches the design working point and, generally, a detailed study of the emittance compensation process providing the optimal value of emittance at the end of the linac. For this purpose a novel beam diagnostic, the emittance-meter, consisting of a movable emittance measurement system, was conceived and built. This paper presents the results of the first measurements with the emittance-meter showing the characteristics and the performance at the SPARC photo-injector.
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THPLS108 | Performance Test of RF Photo-Cathode Gun at the PAL | gun, laser, electron, cathode | 3529 | ||||
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A RF photo-cathode (RF PC) gun with 1.6 cell cavity is installed for the fs-FIR (Femto-second Far Infrared Radiation) facility being built at the Pohang Accelerator Laboratory (PAL). A short, intense, and low emittance electron beams are produced by the RF PC gun. Performance test of the gun is done include the measurement of RF chraterizations such as a resonant frequency, a mode separation, and etcs. The diagnostics of the beam according to the beam parameters such as phase, charge, and energy, and emittance are done. In this article, we present the measurement results of the RF charaterizations and the beam parameter diagnostics of the RF PC gun at the PAL.
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THPLS115 | Simulation and Optimisation of a 100 mA DC Photo-Injector | electron, gun, cathode, ASTRA | 3550 | ||||
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A prototype 100mA injector is presently being designed and manufactured jointly between Thomas Jefferson National Accelerator Facility (J-Lab) and Advanced Energy Systems (AES). This paper discusses the physics optimisation and performance of the injector, which has been studied using the space-charge tracking code ASTRA. The objective is to operate the 7MeV injector with 135pC electron bunches at 748.5MHz repetition rate. We show that the longitudinal and transverse electron bunch properties can be realised within the constraints of the design.
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THPLS123 | A Year's Experience with a Superconducting Undulator in the Storage Ring ANKA | undulator, optics, synchrotron, synchrotron-radiation | 3571 | ||||
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In ANKA the worldwide first superconducting undulator demonstrator designed for a storage ring was operated during the last year. The undulator has 100 periods and a period length of 14 mm. During the first year the heat transfer from the beam to the cold bore was investigated and the spectra and the electrical tunability together with a monochromator was measured. The results are so encouraging that plans exist to equip ANKA with two more undulators, one with the opportunity to double electrically the period length and one with electrically variable polarization direction.
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