| Paper | Title | Page |
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| THPS029 | Simulations of Various Driving Mechisms for the 3rd Order Resonant Extraction from the MedAustron Medical Synchrotron | 3481 |
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The MedAustron medical synchrotron is based on the CERN-PIMMS design and its technical implementation by CNAO [1]. This document elaborates on studies performed on the baseline betatron-core driven extraction method and investigates the feasibility of alternative resonance driving mechanisms like RF-knockout, RF-noise and the lattice tune. Single particle tracking results are presented, explained and compared to analytical results.
[1] M. Pullia, ‘‘Status Report on the Centro Nazionale di Adroterapia Oncologica (CNAO)'', 11th EPAC'08, Genoa, Itlay, June 2008, p. 982 |
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| THPS030 | Layout and Optics of the MedAustron High Energy Beam Transfer Line | 3484 |
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| The MedAustron accelerator complex, which is currently in its final design stage at CERN, is based on the optical principles developed within the Proton Ion Medical Machine study (PIMMS) [bryantpimms]. This paper describes how these principles are practically applied in the layout and optics of the High Energy Beam Transfer line (HEBT) of the MedAustron accelerator facility. Special attention is directed to the optics of the gantry which is designed to fit into the PSI gantry-2 hardware layout, which is foreseen to be copied in collaboration with PSI. | ||
| THPS031 | The Beam Expander System for the European Spallation Source | 3487 |
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| At the European Spallation Source (ESS), neutrons are produced by high energy (2.5 GeV) protons impinging on a target. The lifetime of the target is highly dependent on the beam footprint. In general, the lower the average current density, the longer the lifetime of the target will be. A detailed study of two different expander systems suggested to be used to obtain the desired beam footprint has been undertaken. For reference, a system of quadrupole defocusing is used. The two systems under study are expansion of the beam by magnetic multipoles and raster scanning (painting) of the narrow linac beam over the target area. The designs, specifications, and comparative risks of the three systems will be described. | ||
| THPS033 | Skew Quadrupole Effects on Multi-turn injection Efficiency in the SIS18 | 3490 |
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Funding: DAAD ( Deutscher Akademischer Austausch Dienst) One goal of the SIS18 upgrade scheme is concerned about improving the multi-turn injection (MTI) efficiency, in order to reach the required intensities at the targets and to operate effectively as a booster for SIS100. To improve the limitation of the MTI scheme, there were successful attempts in AGS and PS boosters, to use the skew injection scheme and later it was suggested for SIS18. The strength of the skew quadrupoles is optimized together with the horizontal tune, the difference in horizontal to vertical tunes, the incoming beam parameters and the geometrical limitation of SIS lattice. A good optimization implies the emittance exchange, due to linear coupling, to take place partially and just before the return of the beamlet back to its original position at the septum. The present work was done by simulation using the code PARMTRA and compared with measurements. The results show that, depending on the working point, the skew injection scheme can improve the MTI efficiency from 2% up to 12%, taking into account the loss on the septum from inside and on the vertical acceptance. |
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| THPS034 | Studies on Electron Cloud Dynamics for an Optimized Space Charge Lens Design | 3493 |
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Funding: Work supported by HIC for FAIR. Space charge lenses using a stable electron cloud for focusing low energy heavy ion beams are an alternative concept to conventional ion optics. Due to external fields electrons are confined inside the lens’ volume. In case of a homogeneously distributed electron cloud the linear electric space charge field enables beam focusing free of aberration. Since the mapping quality of the lens is related to the confinement, non-destructive diagnostics has been developed to determine the plasma parameters and to characterize the collective behavior of the confined nonneutral plasma. Moreover, a scaled up space charge lens was constructed for a detailed investigation of the nonneutral plasma properties as well as beam interactions with a stable confined electron cloud. Experimental results will be presented in comparison with numerical simulations. |
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| THPS035 | Collimator Upgrade Plan of the J-PARC Main Ring | 3496 |
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| A halo collimation system is prepared in the middle of injection-straight section in order to localize the beam loss occurred in main ring. It consists of three collimator units. The first unit scatters halo components, and the other two units work as halo catchers. The permitted amount of beam losses in the collimator section is designed to be 450 W at the present. The upgrade plan of halo collimation system is running in order to achieve about ten times larger beam loss capability for high-power beam operation. The collimator upgrade is planned by installing a new collimator set and radiation shields which cover the collimator section. New collimator units are designed to be able to line-out the jaw with a part of radiation shield including the mechanical devices. The design work of collimator units and radiation shields is presented in this report. | ||
| THPS036 | Development of Thin NCS-foils by N+ Ion Beam Sputtering and Their Characteristics | 3499 |
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| We have developed thin Nitride Carbon Stripper foils (NCS-foil) with a higher nitrogen content by ion beam sputtering method with reactive nitrogen gas. Such NCS-foils have been demonstrated that the foils in range of 10-25 ug/m2 have shown long-lifetime as stripper foil against high intensity heavy ion beam bombardment. From the results, we found that the nitrogen element in the carbon foils plays very important role of the foil lifetime. Therefore, in order to investigate further influence of the lifetime on the nitrogen amount in the NCS-foils, we measured the sputtering yield at the different sputtering angles and carbon source materials. We also measured the ratio of nitrogen in carbon foil made at the different sputtering angles, target materials and the sputtering voltages of 4-15 kV by means of RBS method. The foil-lifetime made in above different conditions was measured with a 3.2 MeV Ne+ ion beam. The lifetime does not essentially depend on the sputtering angles and the target materials, and the maximum and average lifetimes showed 240 and 40 times longer than that of the CM-best foils. | ||
| THPS037 | Performance Characteristics of HBC-foils by 650 KeV H− and DC High Intensity Ion Beam Irradiation | 3502 |
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| Newly developed Hybrid type Boron mixed Carbon stripper foils (HBC-stripper foil) are extensively used for not only J-PARC, for but also LANL-PSR since September of 2007. In order to know further characteristics of the HBC-stripper foils, we measured following parameters; foil lifetimes, thickness reduction, uniformity before and after beam irradiation and foil shrinkage, using 3.2 MeV Ne+ DC beam from TIT-Van de Grraff and 650 keV DC proton beam at KEK Cock-Croft accelerators, which are almost the same energy deposition as well as the J-PARC. We also investigated sputtering yield by hydrogen ion beam, thermal conductivity, weight change in heating and density of the HBC-stripper foils. We compared these values with other tested carbon stripper foils such as commercially available carbon foils (CM-foil), synthetic diamond (DM-foil) and nano-tube carbon foils (NTC-foil). Through these experiments, the HBC-stripper foils showed superior performance characteristics, in especially, on the lifetime at temperature higher than 1800K compared with other tested CM-, DM- and NTC-foils. | ||
| THPS038 | Possibility of longitudinal painting injection with debuncher system in J-PARC linac | 3505 |
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| J-PARC linac is presently operating with the output energy of 181 MeV and providing a negative hydrogen beam to the succeeding 3-GeV synchrotron. To achieve the design beam power of 1 MW from the synchrotron, we plan to upgrade the linac beam energy to 400 MeV. In the energy upgrade, we replace the debuncher system installed between the linac and synchrotron. The main roles of the debuncher system are to correct the momentum jitter and to control the momentum spread at the ring injection. Usually, we don’t assume acceleration or deceleration with the debuncher cavities except for passive momentum jitter correction. However, we are studying the possibility of actively controlling the center momentum with debuncher cavities to enable longitudinal painting injection into the succeeding ring as a potential new feature. If it finds feasible, it would provide an additional tuning knob to mitigate the beam loss in the synchrotron. In this paper, we show a beam dynamics design of the new debuncher system with emphasis on the possibility of its application for the longitudinal painting injection. | ||
| THPS039 | Diffusion of a Circulating Beam by the RF-Knockout with a Spectrum including Many Bands | 3508 |
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| The fast control of beam spill extracted from a synchrotron is a key function for the spot scanning irradiation in cancer therapy application. The authors have proposed the extraction method for the application which uses the control of a quadruple field of fast response as well as the RFKO (QAR method). The RF signal for the RFKO should cover a frequency band corresponding to a tune spread. A simulation with continuous RFKO operation, however, showed a spill intensity changes with time largely with only this band. The large change of spill is due to not uniform diffusion of circulating beam and it makes a constant spill difficult in the QAR method. A wider band gives a uniform spill, but it requires a larger Amp power. We proposed a spectrum including many bands around the resonances to reduce the power, since the bands outside around the resonances do not contribute to the diffusion. Such a spectrum has also an advantage to increase spill intensity for the QAR method, using a band so that the RFKO diffuses more inside particles of the separatrix but also it affects little them near the boundary. We can extract several times particles with a same shrink ratio of the separatrix. | ||
| THPS040 | Measurement of the Stripping Efficiency for HBC Stripper Foil in the 3-GeV RCS of J-PARC | 3511 |
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| We have carried out experimental measurement of the stripping efficiency for the newly developed HBC (Hybrid type Boron doped Carbon) stripper foils. The HBC foil is used for charge-exchange injection in the RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) and plays an important role for the RCS operation. We have developed a rather simple but very precise method using which stripping efficiencies for several HBC foils were determined accurately. Importance of knowing an accurate stripping efficiency so as to determine a realistic stripper foil for the RCS operation will be discussed. | ||
| THPS041 | Design of Beam Transport Line from RCS to Target for CSNS | 3514 |
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| China Spallation Neutron Source (CSNS) uses the high energy proton beam to strike the Tungsten target to generate neutrons through spallation reaction. The proton beam is extracted from the Rapid Cycling Synchrotron (RCS), whose beam power reaches 100 kW. For the sake of target lifetime, beam distribution at the target surface is required as uniform as possible. Nonlinear beam density redistribution method with two octupole magnets has been studied. Also some simulation and theoretical calculation have been done. According to the simulation result, the beam density at the target is optimized and the beam loss is under control. | ||
| THPS042 | Feasibility Studies of the Foil Scattering Extraction in CSNS/RCS | 3517 |
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| A slow extraction based on foil scattering was suggested in the rapid cycling synchrotron of China Spallation Neutron Source for particle calibration. Protons with large scattering angle will be extracted during 2 ms at the end of each beam cycle, via a carbon foil. The feasibility of the extraction scheme is investigated. The extraction efficiency is studied by both single turn and multi-turn simulations with FLUKA and ORBIT, respectively. Beam losses due to multiple scattering to the downstream components are predicted. | ||
| THPS044 | Study of Charge Exchange Injection in HITFiL | 3520 |
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| A new accelerator complex dedicated to hadron cancer therapy, Heavy-Ion Therapy Facility in Lanzhou (HITFiL), is proposed and designed. Based on the operating experience and existing technology on HIRFL-CSR, a heavy-ion cyclotron is used as an injector instead of a linac. A heavy-ion synchrotron as main component is designed with special attention paid to compact structure, high reliability and low cost. HITFiL is designed to accommodate both proton and carbon-ion using the same injecting channel but different injecting points. Charge exchange injection scheme, which is more efficient compared with single-turn injection but less costly compared with multiple multi-turn injection aided by electron-cooling, is adopted. H2+ or C5+ beams, pre-accelerated by the cyclotron, are stripped into H+ or C6+ by a carbon foil at injection point, then injected and merged into synchrotron coasting orbit. The design of the injection system is presented in this paper. The whole injection process is simulated, optimization of parameters on injecting efficiency, painting scheme and emittance growth are performed. The resulting beam distribution in phase space after injection is achieved. | ||
| THPS045 | Beam Emittance Measurement in the Injection Beam Line for a Cyclotron Accelerator Mass Spectrometer | 3523 |
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Funding: This work was supported by National Research Foundation of Korea (NRF) Grant No. 20110018946, and also by World Class University project of the NRF. A carbon beam was extracted and measured in the injection beam line built for an accelerator mass spectrometer (AMS) based on a cyclotron. The cyclotron AMS has been designed to realize a compact AMS having a mass resolving power of around 4000 for a negative 14C beam. The beam line is a prototype to ensure the capability to match the beam phase space with the acceptance of the cyclotron. The injection beam line consists of an ion source, Einzel lens, rf buncher, 90 degree dipole magnet and a beam diagnostic box with a slit system. The ion source with a hot filament is a commercial product, and all other elements were designed and built in house. Some measurement results of the beam line components as well as beam emittance will be presented. |
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| THPS046 | Transport Beam Lines for NICA Accelerator Complex | 3526 |
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| In the last years Nuclotron-based Ion Collider fAcility (NICA) project is being developed by Joint Institute for Nuclear Research (JINR), Dubna, Russia. The goal of the project is to construct new accelerator complex that will be used for colliding ion beams on first stage and colliding polarized proton/deuteron beams on second stage of the project. NICA accelerator complex will consist of two linear accelerators, two superconducting synchrotrons, two superconducting storage rings of the collider and transport beamlines. Geometry and magnetic system of NICA beamlines are presented in this report. Results of beam dynamics simulations within the beamlines are considered. | ||
| THPS047 | New Injection and Extraction at CRYRING for FLAIR | 3529 |
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| As a preparation for a future transfer of CRYRING to FLAIR at FAIR in Darmstadt, Germany, we have installed and tested a slow extraction system. At FLAIR CRYRING will be used for deceleration of antiprotons from 30 MeV to 0.3 MeV. The tests of the slow extraction show that the beam can be extracted during 2 s with 30-60% efficiency and with rather constant amplitude, apart from noise from 50 Hz harmonics. A new injection system has also been designed. It will be able to inject 30 MeV antiprotons from NESR as well as 0.3 MeV/u ions created in a separate ion source and accelerated in an RFQ. | ||
| THPS049 | Feasibility Study of a CERN PS Injection at 2 GeV | 3535 |
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| In the framework of the potential CERN PS Booster (PSB) energy upgrade, a study was initiated to look into the possibilities and constraints to inject protons into the PS at kinetic energies up to 2 GeV, for LHC type beams and other (high intensity) beams. This paper highlights the identified bottlenecks and potential solutions and addresses the resulting requirements for the hardware in the transfer line and injection region of the PS. In conjunction with the proposed upgrade of the PSB-PS transfer line hardware the optics can be changed for different cycles. Optics solutions optimized for the different requirements of LHC type and other beams are presented. | ||
| THPS050 | The High Energy Beam Transport System for the European Spallation Source | 3538 |
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| As part of the accelerator design update for the European Spallation Source (ESS), we present results from a detailed study of the High Energy Beam Transport (HEBT) line. The HEBT is a transport line around 100 m long, which connects the 2.5-GeV linac to the target. The linac will deliver a current of 50 mA, a pulse length of 2 ms and a repetition rate of 20 Hz, and losses are of utmost importance. Presumably, the HEBT will continue the 10 m period focusing structure of the linac. Two bends – overall, achromatic – will be needed to connect the different vertical levels between the linac and the target. A number of design aspects will be discussed here: space for future linac cryostats, the need and location for collimation, the location of the tuning beam dump and the associated beam optics, and the beam expander system, which provide the desired beam footprint on the target (see also separate contribution). A proposed design including options will be described together with hardware specifications. | ||
| THPS051 | Development of Fragmented Low-Z Ion Beams for the NA61 Fixed-target Experiment at the CERN SPS | 3541 |
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| The NA61 experiment, aims to study the properties of the onset of deconfinement at low SPS energies and to find signatures of the critical point of strongly interacting matter. A broad range in T-μB phase diagram will be covered by performing an energy (13A-158A GeV/c) and system size (p+p, Be+Be, Ar+Ca, Xe+La) scan. In a first phase, fragmented ion beams of 7Be or 11C produced as secondaries with the same momentum per nucleon when the incident primary Pb-ion beam hits a thin Be target will be used. The H2 beam line that transports the beam to the experiment acts as a double spectrometer which combined with a new thin target (degrader) where fragments loose energy proportional to the square of their charge allows the separation of the wanted A/Z fragments. Thin scintillators and TOF measurement for the low energy points are used as particle identification devices. In this paper results from the first test of the fragmented ion beam done in 2010 will be presented showing that a pure Be beam can be obtained satisfying the needs of the experiment. | ||
| THPS052 | Studies on Transverse Painting for H− Injection into the PSB | 3544 |
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| Linac4 will inject 160 MeV H− ions in to the CERN PS Booster (PSB). This will allow to reduce space charge effects and increase beam intensity but will require a substantial upgrade of the injection region, with the implementation of a charge-exchange multi-turn injection scheme. The PSB has to provide beam to several users with different requirements in terms of beam intensity and emittance. Four kicker magnets (KSW), which are already installed in the PSB lattice, will be used to accomplish painting in the horizontal phase space to match the injected beams to the required emittances. Double linear functions, with varying slopes for each user, have been defined for the KSW generators waveforms according to detailed beam dynamic studies for all target intensities and emittances. Effect of space charge, injection offsets, dispersion and betatron mismatch have been taken into account. Preliminary studies have been carried out to evaluate how to obtain the required vertical emittance and the option of a transverse painting, also in the vertical plane, is explored. | ||
| THPS053 | Results from the HiRadMat Primary Beam Line Commissioning | 3547 |
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| The High Radiation to Materials facility (HiRadMat) is a new experimental area at CERN, for studies of the impact of high-intensity pulsed beams on accelerator components and materials. The beam is delivered from the SPS by a new primary beam line, which has been constructed during the 2010/11 winter technical stop. The paper summarizes the construction phase and describes the results from the beam line commissioning in spring 2011. Beam parameter and aperture measurements are presented, as well as steering tests. A special emphasis has been put on the handling of the exceptionally flexible beam line optics in the control system. | ||
| THPS054 | Injection and Extraction Considerations for a 2 GeV RCS at CERN | 3550 |
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| Conceptual studies have been made for a 2 GeV RCS at CERN as a possible replacement of the four-ring PS Booster. The lattice design has to accommodate suitable straight sections for a 160 MeV H− charge exchange injection system, and for a 2 GeV fast extraction system. The design constraints for the injection and extraction systems are described, together with the proposed concepts and potential equipment limitations. In particular, the features of different possible H− injection configurations are compared. | ||
| THPS057 | Stripping Foil Simulations for ISIS Injection Upgrades | 3556 |
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| ISIS, the pulsed neutron and muon spallation source located at the Rutherford Appleton Laboratory (UK), currently delivers a mean beam power of 0.2 MW to target. A 70 MeV H− linear accelerator feeds into a 50 Hz, 800 MeV proton synchrotron (through a 0.3·10-6 m Aluminium Oxide stripping foil), accelerating up to 3·1013 protons per pulse. Potential injection scheme upgrades, aiming to raise average beam power towards 0.5 MW with a new 180 MeV linear accelerator, are being studied. Detailed consideration of the injection stripping foil forms a key element of this study: scattering, stripping efficiency and foil lifetime are significant factors in determining loss levels, which consequently limit operational intensity. This paper describes the identification of a suitable stripping foil specification for successful 180 MeV H− charge exchange injection into the ISIS synchrotron. Simulation code was developed to investigate electron stripping, scattering events and temperature rises, in order to witness their subsequent effect on foil lifetime. ANSYS models were also used to investigate the heat transfer and temperature distribution within thin foils. | ||
| THPS058 | Third Integer Resonance Slow Extraction Using RFKO at High Space Charge. | 3559 |
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| A proposal to search for direct mu->e conversion at Fermilab requires slow, resonant extraction of an intense proton beam. Large space charge forces will present challenges, partly due to the substantial betatron tune spread. The main challenges will be maintaining a uniform spill shape and moderate losses at the septum. We propose to use "radio frequency knockout" (RFKO) for fine tuning the extraction. Strategies for the RFKO method will be discussed here in the context of the mu->e experiment. Feasibility of this method has been demonstrated using simulations. | ||