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| MOAP02 | Recent Beam Commissioning Results from the Spallation Neutron Source | linac, extraction, proton, emittance | 6 | ||
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The Spallation Neutron Source accelerator complex consists of a 2.5 MeV H- front-end injector system, a 186 MeV normal-conducting linear accelerator, a 1 GeV superconducting linear accelerator, an accumulator ring and associated beam transport lines. The beam commissioning campaign of the SNS accelerator complex, initiated in 2002, has been performed in seven discrete runs as each successive portion of the accelerator complex has been installed. The final beam commissioning run, in which beam was transported to the liquid mercury target was recently completed. In the course of beam commissioning, most beam performance parameters and beam intensity goals have been achieved at low duty factor. The beam performance and beam dynamics measurements of the linac and ring will be presented.
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| MOAP03 | Comparative Studies of Proton Accelerators for High Power Applications | proton, factory, linac, klystron | 11 | ||
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There are many applications need high power proton accelerators of various kinds. However, each type of proton accelerator can only provide beam with certain characteristics, hence the match of accelerators and their application needs careful evaluation. In this talk, the beam parameters and performance limitations of linac, cyclotron, synchrotron, and FFAG accelerators will be studied and their relative merits for application in muon, neutron, neutrino, and ADS assessed in terms of beam energy, intensity, bunch length, repetition rate, and beam power requirements. A possible match between the applications and the accelerator of choice will be presented in a matrix form. The accelerator physics and technology issues and challenges involved will also be covered.
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| MOAP04 | Recent progresses on FFAG accelerators | proton, acceleration, focusing, emittance | 16 | ||
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| MOBP01 | ISIS Upgrades – A Status Report | synchrotron, proton, linac, rfq | 20 | ||
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Since 2002 several accelerator upgrades have been made to the ISIS spallation neutron source at the Rutherford Appleton Laboratory in the UK, and upgrades are currently continuing in the form of the Second Target Station Project. The paper will review the upgrade processes, and will also look forward to possible future schemes at ISIS beyond the Second Target Station.
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| MOCP01 | Beam intensity upgrade at Fermilab | proton, booster, antiproton, extraction | 34 | ||
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| MOCP02 | High-power accelerators in China: status and outlook | linac, proton, injection, dipole | 39 | ||
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High intensity accelerator research is a relatively new subject in China. Recent program includes the accelerator-driven sub-critical power generation and the Beijing Spallation Neutron Source (BSNS) project. The Beijing Spallation Neutron Source (BSNS) is a newly approved project based on a H- linear accelerator and a rapid cycling synchrotron. During the past year, several major revisions were made on the design including the type of the front end, the linac frequency, the transport layout, the ring lattice, and the type of ring components. Possible upgrade paths were also laid out: based on an extension of the warm linac, the ring injection energy and the beam current could be raised doubling the beam power on target to reach 200 kW; an extension with a superconducting RF linac of similar length could raise the beam power near 0.5 MW. Based on these considerations, research and development activities are started. In this paper, we discuss the rationale of design revisions and summarize the recent works.
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| TUAY01 | Overview of proton driver studies for neutrino and muon factories | proton, linac, synchrotron, factory | 64 | ||
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There are a number of proton driver studies around the world: SPL at CERN, an 8 GeV SCRF linac at Fermilab, AGS upgrade at BNL, Proton Driver for the International Scoping Study on Neutrino Factories and Superbeams, FFAG based proton driver in Japan, etc. This talk will give an overview of them and compare their similarities and differences. Common R&D projects and possible inter-laboratory collaborations will be discussed.
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| TUAZ02 | High-Intensity Beam Collimation and Targetry | collimation, beam-losses, proton, radiation | 74 | ||
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Principles, design criteria and realization are described for reliable collimation systems for the high-power accelerators (Fermilab Booster and Main Injector, SNS, J-PARC), hadron colliders (Tevatron and LHC) and e+e- linear colliders (ILC). Factors affecting the expected and achieved collimation performances are analyzed. Functionality of collimators as the key elements of the machine protection system are considered using as an example a recent beam accident case in the Tevatron. A substantial progress on the crystal collimation front is described. The key issues are considered in design of high-power target systems and achieving their best performance. Simulation code requirements and recent benchmarking results are presented. A status of conventional neutrino targets and neutrino factory target concepts is described along with performed and planned beam tests. Overview of the target and collimator material beam tests concludes this report.
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| TUBY04 | Operational flexibility of the SPL as proton driver for neutrino and other applications | linac, proton, factory, dipole | 150 | ||
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The pulse structure of proton linacs is determined by the linac energy, the RF system, and the maximum duty cycle of the source. Short bursts of protons in the microsecond range can be achieved by adding an accumulator ring and a reduction of the bunch length to the order of nanoseconds can be accomplished with an additional bunch compressor ring. The size of the rings along with their RF frequency determines the time structure of the proton driver output burst to hit the target. This pulse structure can be further modified using multiple fillings of the accumulator and compressor rings within one linac pulse. This paper illustrates the possible modes of operation of the SPL at CERN along with its limitations at various energies in combination with accumulator and compressor rings.
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| TUBZ04 | Experimental Studies of Targets and Collimators for High Intensity Beams | proton, radiation, controls, isotope-production | 143 | ||
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Intense muon or neutrino beams require high-performance targets intercepting multi MW proton beams. To achieve it one must push the envelope of the current knowledge regarding material behavior and endurance for both short and long exposure. It is also true for collimator structures intercepting the halo of the intense beam under normal or the entire beam during off-normal conditions. The limitations of most materials in playing such pivotal roles have led to an extensive search and experimentation with new alloys and composites that, at first glance, appear to possess the right combination of properties satisfying target and /or collimation requirements. In this study, a number of new and “smart” materials are experimentally evaluated for resilience to radiation damage and potential use in target and collimation schemes. These include targets for the muon collider and the neutrino superbeam as well as LHC collimation. Results of the on-going experimental effort under way at BNL and involving heavy irradiation of candidate materials using 200 MeV proton beams and post-irradiation analysis for irradiation damage assessment will be presented.
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| WEAZ07 | Shock wave propagation near 7 TeV proton beam in LHC collimator materials | proton, coupling, radiation, electron | 241 | ||
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A study is presented to estimate the influence of the impact of a 7 TeV proton beam on the physical-mechanical material properties, such as C for collimators, and Cu elsewhere. The high energy stored in each bunch can produce a shock wave near the impacting proton beam in these materials. The theoretical model for the investigations of shock wave propagation in the collimator materials takes into account ionization, electronic excitation, and energy transfer from excited electronic subsystem in the materials to the ionic subsystem. The change of other physical properties of the material is also considered. The deposited energy is calculated with FLUKA [1]. The numerical results of the microstructure change in the material are presented for different numbers of bunches. The method allows investigating changes of density and internal pressure, the distributions of atomic and sound velocities, and the temperature profiles in electronic and ionic subsystems of materials near the front of shock wave. These results are very relevant for the understanding the behavior of collimator materials used in LHC under 7 TeV proton beam.
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[1] A. Fasso et al. The physics models of FLUKA: status and recent development, CHEP 2003, LA Jolla, California, 2003 |
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| THAW03 | RF Barrier Cavity Option for the SNS Ring Beam Power Upgrade | electron, space-charge, proton, injection | 298 | ||
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RF barrier cavities present an attractive option for facilitating the path to higher beam intensity in the SNS power upgrade. Barrier cavities lead to flat longitudinal current densities, thus minimizing bunch factor effects. In addition to allowing more beam to be injected in this fashion, flat current profiles may lead to increased e-p instability thresholds due to reduced multipacting during the trailing stage of the bunch. Finally, it is possible to inject self-consistent beam distributions into barrier buckets, thus providing the additional advantages of uniform transverse beam density (good for meeting target constraints) and little or no halo (good for low losses). Simulations addressing all these issues will be presented and discussed.
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| THAY02 | Progress in slip stacking and barrier-RF | injection, booster, antiproton, simulation | 293 | ||
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Slip stacking for pbar production has been operational since December 2004 and increased the beam intensity on pbar target more than 60%. We plan to use slip stacking for NuMI neutrino experiment for effectively increasing intensity to NuMI target by about a factor two in a 2.2 sec MI cycle. In parallel with slip stacking, we plan to study fast momentum stacking using barrier buckets. One barrier rf system has been installed and tested, and second system is being installed during the current shutdown.
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| THAY04 | Review of high-brightness proton and ion acceleration using pulsed lasers | proton, laser, ion, 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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| THAZ01 | Experience with high-power operation of the PSI proton accelerator facility | radiation, cyclotron, proton, diagnostics | 274 | ||
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The PSI proton accelerator delivers a maximun current of 2 mA (routinely 1.9 mA) at 590 MeV. Ongoing developments aim at an upgrade of the beam current to 3 mA. This will result in an increase of the beam power from 1.2 to 1.8 MW on the pion/muon production targets and from 0.8 to 1.2 MW on the neutron spallation source SINQ. Our approach to the safe operation of a facility a these power levels will be presented. This includes considerations on the design of the cyclotrons, the beam lines and the tools to handle highly radioactive components. The protection of the facility via device controls, beam diagnostics and loss monitoring will be discussed. The specific requirements for operation with a sensitive liquid metal target like MEGAPIE will also be addressed.
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| THAZ02 | SNS Commissioning Strategies and Tuneup Algorithms | linac, controls, injection, quadrupole | 283 | ||
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The Spallation Neutron Source (SNS) has been recently commissioned. The strategies for the initial beam commissioning of the superconducting linac (SCL) and storage ring will be discussed. The SCL commissioning had to accommodate an unanticipated wide range of cavity performance, compared to design expectations. Methods for setting cavity phases and determination of amplitudes will be discussed. The ring commissioning involved the usual establishment of a circulating beam, and then measurement and correction the tune and beta functions, all with a low intensity beam. Then the gradual increase of beam intensity and commissioning of RF and phase space painting were investigated. The methods to accomplish these tasks will be discussed. In general, the first order beam behavior is well understood. Key factors in the successful commissioning are: flexibility in accommodating beam conditions that are different from the design, good communication between the different groups, and attention to detail. Examples for these factors will be emphasized.
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| THBY01 | Acceleration of Intense Beams of Highly-Charged Ions using Direct Plasma Injection Scheme | ion, rfq, extraction, 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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| FRAP03 | Summary of Working Group C+G (Part I) | beam-losses, extraction, collimation, injection | 365 | ||
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