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| MOBP02 | FAIR at GSI | antiproton, storage-ring, synchrotron, heavy-ion | 24 | ||
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A new faciliy for antiproton and ion research (FAIR) is being planned and prepared to be built at GSI, Germany. R&D and prototype design is presently conducted at GSI and several other institutes worldwide, representing the future FAIR member states. Furthermore a major upgrade program for the running GSI accelerators, the heavy ion linac UNILAC and the heavy ion synchrotron SIS18 has been started. In parallel, the plannings for buildings and tunnels and the permit procedure for construction were launched. The new facility will consist of a two stage heavy ion synchrotron SIS100/300 for the generation of intense heavy ion and proton beams. These beams can be delivered wether as short compressed bunches for the production of secondary beams with subsequent processing in storage rings or as slow extracted beams with high duty cycle for fixed target experiments. The quality and intensity of the produced secondary beams (rare isotope and antiproton beams) will be significantly improved in a number of storage rings used for stacking, beam cooling and for internal target experiments.
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| MOBP03 | Upgrade of BNL Accelerator Facility | luminosity, electron, proton, heavy-ion | 29 | ||
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A number of upgrades are planned for the Brookhaven accelerator facility that is primarily made of RHIC and its injector, the AGS. The RHIC luminosity and proton polarization are to evolve towards the Enhanced Design parameters by 2008. A new Electron Beam Ion Source is under development, and commissioning is expected in 2009. The aim of the RHIC II upgrade is to increase the heavy ion luminosity by an order of magnitude, through electron cooling in store. With the addition of an electron ring, the high-luminosity electron-ion collider proposal eRHIC can be realized. Studies have also been done for a new injector to the AGS replacing the present Booster for an upgrade of the beam average power to 1 MW at 28 GeV. The new injector to match the AGS repetition rate can be either a 1.5-GeV SCL or a FFAG accelerator. With the upgrade of the injector complex, neutrino superbeams could be produced.
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| TUAX06 | Electron cloud and single-bunch instabilities in the Relativistic Heavy Ion Collider | electron, beam-losses, vacuum, emittance | 117 | ||
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Electron cloud is one of the leading mechanisms that limit the performance of high intensity circular accelerators and colliders. Electron cloud in RHIC is in an intermediate regime sharing features of both the long-bunch (PSR) and short-bunch (photon factories) machines. Vacuum-pressure rises, transverse tune shifts, and electron flux are observed at injection, upon transition crossing, and at top energy. Transverse emittance growth, fast instabilities, and beam loss also occur upon transition crossing. Mitigation measures are implemented both to reduce the production of electron cloud and to control the beam stability. This paper summarizes the observation and initial analysis of the electron-cloud effects at RHIC.
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| TUAY03 | Design of the Driver Linac for the Rare Isotope Accelerator | linac, rfq, heavy-ion, acceleration | 89 | ||
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The proposed design of the Rare Isotope Accelerator (RIA) driver linac is based on cw fully superconducting 1.4 GV linac capable to accelerate uranium ions up to 400 MeV/u and protons to 1 GeV with 400 kW beam power. Extensive research and development effort has resolved many technical issues related to the construction of the driver linac and other systems of the RIA facility. Particularly, newly developed high-performance SC cavities will provide the required voltage for the driver linac using 300 cavities designed for six different geometrical betas. We are currently looking at alternatives for staging the facility to reduce the initial cost by about a factor of two. A possibility for the first stage includes ~850 MV driver linac to deliver uranium beams at 200 MeV/u and protons at 550 MeV. Thanks to successful tests of the front end systems, 400 kW beams can be obtained with increased intensities of heavy-ion beams from the ECR and higher rf power in the linac even at the first stage of the facility.
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| TUAZ06 | Development of hybrid typoe carbon stripper foils with high durability against 1800K for RCS of J-PARC | injection, linac, vacuum, laser | 122 | ||
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We have successfully made long-lived and hybrid , thick, boron mixed carbon stripper foils for high energy and high intensity accelerators. The foils were made by the controlled DC arc-discharge method, and the thickness is wide range from 50 to 600 ug/cm2. The lifetime of the foils was tested with use of 3.2 MeV Ne+DC beams of 2.5 uA, in which a significant of energy was deposited in the foils and thus we could simulate the condition by high power accelerator. The lifetime in maximum was shown to be extremely long, 102 and 410 times longer those of diamond and commercially available best carbon foils, respectively.
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| WEAY01 | New advances in beam cooling | electron, storage-ring, beam-cooling, antiproton | 162 | ||
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New developments in beam cooling since ICFA’2004 seminar are presented with concentration on trends in electron cooling, stochastic cooling, muon cooling and beam crystallization - the trends, which, as one can expect, will mark the future in the cooling methods applications.
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Keywords: particle storage rings, cooling methods, electron beam, Schottky noise. |
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| WEAY03 | Experimental studies of stability issues at HIMAC cooler | electron, resonance, feedback, injection | 197 | ||
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We have investigated coherent transverse instability when high-density circulating-ion beam was obtained with cool-stacking injection in the HIMAC synchrotron. By using a cooled beam and the Oxygen gas-sheet beam profile monitor, further, we have observed a particle trapping in resonance crossing. We will report these experimental studies at the HIMAC synchrotron.
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| WEAY04 | Analysis of the magnetized friction force | electron, simulation, plasma, interaction-region | 210 | ||
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A comprehensive examination of theoretical models for the friction force, in use by the electron cooling community, was performed. Here, we present our insights about the models gained as a result of comparison between the friction force formulas and direct numerical simulations, as well as studies of the cooling process as a whole.
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| WEAY05 | New experimental results on electron cooling at COSY-Juelich | electron, proton, injection, scattering | 223 | ||
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Recent electron cooling results of a proton beam at COSY – Juelich are summarized. The influence of residual gas ions trapped in the electron beam on the cooled beam stability as well as methods to suppress the instabilities are described. Results on the numerical simulation for the formation of a crystalline proton beam in COSY using the BETACOOL code and results of experimental investigations of the cooling process at extremely low proton beam intensity are reported. Future plans are briefly addressed.
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| WEAY06 | Experimental Strategy for Realization of 3-D Beam Ordering with Use of Tapered Cooling at S-LSR | laser, coupling, vacuum, proton | 231 | ||
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At ICR, Kyoto University, an ion storage/cooler ring, S-LSR has been operated since the October, 2005. S-LSR has capability of dispersion free mode* throughout the whole circumference in order to avoid the shear heating** due to momentum dispersion of ion beam orbits. With such a mode, we need a special devise to develop necessary coupling between the longitudinal and transverse degrees of freedom for 3-dimensional laser cooling.*** A Wien Filter, in which the magnetic and electric fields overlap with strengths compensating each other for ions with a certain velocity, is to be utilized in the straight section where the usual laser cooling is applied. Due to the potential difference caused by the electric field in the Wien Filter, the difference in horizontal position of the circulating ion creates the difference of the equillibrium energy after laser cooling, which realizes "Tapered Cooling"****. In the present paper, a possible strategy of experimental approach at S-LSR toward 3-dimensional crystalline ion beams with use of the Wien Filter is to be presented.
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* M. Ikegami et al., PR-STAB,7, 120101(2004). |
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| WEBY01 | Commisioning of Electron Beam Cooling at S-LSR | electron, beam-losses, proton, feedback | 247 | ||
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S-LSR is a new compact ion cooler ring at Kyoto University. The circumference is 22.557 m. The commissioning of the electron cooling was started using the 7 MeV proton beam from November, 2005. The total length of the electron cooler is 1.63 m. In order to maximize the effective cooling length in the limited space, the magnetic field of the solenoid and the troid coils was calculated precisely by the 3D code. The electrostatic deflector for the electron and the steering magnet for the ion are placed in the troid. The performances of these devices are evaluated by the cooling measurements. Experiments using the electron cooling are also stared. One is an induction sweep cooling of the proton beam. It is an cooling with the assist of the induction acceleration and possible to reduce the cooling time of the hot ion beams like secondary particles. We also observe the behavior of the cooled ion beam in the small ion number case and the large ion number case. We discuss about the possibility of the phase transition of the proton in the former case and discuss about the coherent instability conditions in the latter case.
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| WEBY03 | Experimental studies of IBS in RHIC and comparison with theory | emittance, simulation, lattice, coupling | 259 | ||
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A high-energy electron cooling system is presently being developed to overcome emittance growth due to Intra-beam Scattering (IBS) for heavy ion operation in RHIC. A critical item for choosing appropriate parameters of the cooler is an accurate description of the IBS. The analytic models were verified vs dedicated IBS measurements. Analysis of the 2004 data with the Au ions showed very good agreement for the longitudinal growth rates but significant disagreement with exact IBS models for the transverse growth rates. Experimental measurements were improved for the 2005 run with the Cu ions. Here, we present comparison of the 2005 data with theoretical models.
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| THAW01 | New simulation capabilities of electron clouds in ion beams with large tune depression | electron, simulation, quadrupole, bunching | 279 | ||
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We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D “slice” e-cloud code POSINST [M. Furman, this workshop], as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new “drift-Lorentz” particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX) [experimental results discussed by A. Molvik, this workshop]. We will describe the capabilities and simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC).
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| THAW02 | New experimental measurements of electron clouds in ion beams with large tune depression* | electron, quadrupole, diagnostics, simulation | 288 | ||
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We study electron clouds in high perveance beams (K = 8E-4) with a large tune depression of 0.2 (defined as the ratio of a single particle oscillation response to the applied focusing fields, with and without space charge). These 1 MeV, 180 mA, K+ beams have a beam potential of +2 kV when electron clouds are minimized. Simulation results are discussed in a companion paper [J-L. Vay, this Conference]. We have developed the first diagnostics that quantitatively measure the accumulation of electrons in a beam [M. Kireeff Covo, et al., to be submitted to Phys. Rev. Lett.]. This, together with measurements of electron sources, will enable the electron particle balance to be measured, and electron-trapping efficiencies determined. We measure and simulate ~10 MHz electron oscillations in the last quadrupole magnet when we flood the beam with electrons from an end wall. Experiments where the heavy-ion beam is transported with solenoid magnetic fields, rather than with quadrupole magnetic or electrostatic fields, are being initiated. We will discuss the initial results using electrode sets (in the middle and at the ends of magnets) to either expel or to trap electrons within the magnets.
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| THAW07 | Transverse electron-antiproton instability in the Recycler Ring | coupling, electron, resonance, impedance | 334 | ||
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Lifetime degradation of electron-cooled ions was observed at several electron coolers. In the Recycler, both the lifetime drop and emittance growth of the e-cooled pbars are seen. A possible reason for that can be a coherent interaction between the electron and antiproton beams. A theoretical model of this instability is presented, and a practical recommendation for its suppression is explained and discussed.
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| THAY04 | Review of high-brightness proton and ion acceleration using pulsed lasers | proton, laser, target, electron | 319 | ||
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In the last few years, intense research has been conducted on laser-accelerated ion sources and their applications. These sources have exceptional properties, i.e. high brightness and high spectral cut-off, high directionality and laminarity, short burst duration. We have shown that for proton energies >10 MeV, the transverse and longitudinal emittance are respectively <0.004 mm-mrad and <10-4 eV-s, i.e. at least 100-fold and may be as much as 104-fold better than conventional accelerators beams. Thanks to these properties, these sources allow for example point-projection radiography with unprecedented resolution. They also open new opportunities for ion beam generation and control, and could stimulate development of compact ion accelerators for many applications. We have shown [*] that there is an optimum in the laser pulse duration of ~200 fs-1 ps, with a needed laser energy level of 30 to 100 J, in order to achieve e.g. 200 MeV energy protons. Also, as, for such applications beam control is an essential requirement, we have developed [**] an ultra-fast laser-triggered micro-lens that allows tuneable control of the beam divergence as well as energy selection.
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[*] J. Fuchs et al., Nature Physics 2, 48 (2006). |
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| THAY06 | Fast-Pulsed Superconducting Magnets | dipole, synchrotron, antiproton, quadrupole | 324 | ||
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Up to now only one synchrotron (Nuclotron at JINR, Dubna) has been equipped with fast-pulsed superconducting magnets. The demand for high beam intensities leads to the requirement of fast-pulsed, periodically cycling magnets for synchrotrons and fast-pulsed magnets for storage rings. An example is FAIR (Facility for Antiproton and Ion Research) at GSI, which will consist of two synchrotrons in one tunnel and several storage rings. The fast field ramp rate and repetition frequency introduce many magnet design problems and constraints in the operation of the accelerator. Persistent currents in the superconductor and eddy currents in wire, cable, iron and vacuum chamber reduce the field quality and generate cryogenic losses. A magnet lifetime of 20 years is anticipated, resulting in up to 108 magnet cycles. Therefore special attention has to be paid to magnet material fatigue problems. R&D work is being done in collaboration with many institutions, to reach the requirements mentioned above. Model dipoles were built and tested. The results of the R&D are reported. The advantages of the use of low field, fast pulsed superconducting, compared to resistive, magnets will be discussed.
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| THAY07 | SC Spoke Cavity | linac, proton, hadron, beam-loading | 337 | ||
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Superconducting (SC) TEM-class spoke cavities have been an area of active research during the past decade with application to cw and pulsed ion linacs required for proposed facilities world-wide. Single- and multi-spoke geometries have been developed for use with ions over the full mass range and with velocities 0.2 < v/c < 0.8. Spoke cavities for this range, generally designed for 4 K operation, have several advantages over 2 K elliptical-cell cavities stemming mostly from the lower operating frequency. However, recent spoke-cavity results in 2 K operation, based on new and evolving cavity processing techniques such as clean assembly and hydrogen degassing, show very low rf losses even for high surface fields (EPEAK ~30 MV/m) required in operations. 2K results indicate even higher voltage gains per cavity with reduced heat loads are possible. Other implications of 2 Kelvin spoke cavity operation for ion linacs are discussed.
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| THAZ04 | Commissioning and Operational Scenarios of the LHC Beam Loss Monitor System | beam-losses, collimation, simulation, superconducting-magnet | 314 | ||
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One of the most critical elements for the protection of CERN’s Large Hadron Collider (LHC) is its beam loss monitoring (BLM) system. It aims to prevent the super conducting magnets from quenching and to protect the machine components from damages, as a result of critical beam losses. The contribution will discuss the commissioning procedures of the BLM system and the envisaged operational scenarios. About 4000 monitors will be installed around the ring. The specification for the BLM system includes a factor of 2 absolute precisions on the prediction of the quench levels, a wide range of integration times (100 us to 100 s) and a fast (one turn) trigger generation. When the loss rate exceeds a pre-defined threshold value, a beam abort is requested. Magnet quench and damage levels vary as a function of beam energy and loss duration. Consequently, the beam abort threshold values vary accordingly. By measuring the loss pattern, the BLM system helps to identify the loss mechanism. Furthermore, it will be an important tool for commissioning, machine setup and studies. Special monitors will be used for the setup and control of the collimators.
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| THBY01 | Acceleration of Intense Beams of Highly-Charged Ions using Direct Plasma Injection Scheme | rfq, extraction, target, plasma | 341 | ||
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Laser Ion Source (LIS) is the most intense source of highly-charged ions capable to provide beams with current 10 / 100 mA and pulse durations 1 / 10 μs. Such parameters well meet requirements of single turn injection into synchrotron rings and FFAG. Few years ago Direct Plasma Injection Scheme (DPIS) was proposed to extract and accelerate intense ion beams from laser induced plasma. By this approach extraction of ions happens almost inside first acceleration cell of RFQ, eliminating severe space charge problems in LEBT and LEBT itself. About 35 mA of 12C4+ ions and 17 mA of 12C6+ ions were accelerated by RFQ up to 100 keV/u using DPIS. Amplitude of total current of carbon ions is equal to 60 mA. The latest results on 27Al and 56Fe ions acceleration using DPIS are presented. The results obtained show that DPIS is, probably, the best choice as a high current injector of highly-charged ions for FFAG.
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| FRAP05 | Summary of Working Group D | electron, scattering, simulation, beam-cooling | 372 | ||
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| FRAP07 | Summary of Working Group F | laser, acceleration, proton, synchrotron | 375 | ||
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