Edinburgh University, Edinburgh
TRIUMF, Vancouver
Since the 1980s the nuclear physics community has pursued the development of intense and exotic radioactive ion beams for many areas of study including astrophysics. The myriad of radionuclides that exist fleetingly inside explosive stellar scenarios are involved in nuclear reactions which are extremely difficult to model from theory, and in these cases experimental data is crucial. The measurement problems of astrophysics often require not only the most sensitive detectors and most intense radioactive beams, but also the right combination of experimental facilities, accelerators and detectors. The community has tackled these problems in a variety of different ways, with many labs already active or coming online with new aggressive accelerator, isotope production and measurement technology ready to target the big astrophysics questions. This talk gives an overview of some experimental methods and facilities used to derive astrophysically-relevant nuclear properties and highlights the places in the world that perform these studies.
RIKEN Nishina Center, Wako
The RIKEN RI Beam Factory (RIBF) is pushing the limits of energy for heavy ion cyclotrons. The first experiment of the RIBF has successfully finished with the discovery of new isotopes 125Pd and 126Pd* in June 2007 with a 345-MeV/nucleon uranium beam. However, the total transmission efficiency was limited to be less than 1%. In addition, a carry-over of oil was found in the refrigerator of the Superconducting Ring Cyclotron (SRC), which was the main accelerator of the RIBF. To solve these problems, we have improved beam monitors, upgraded the oil remover system of the compressor of the liquid helium cryogenic plant at SRC and made a series of acceleration tests. As a result, 0.3 pnA of a 345-MeV/nucleon uranium beam was stably delivered to RIBF users in November 2008 and a 345-MeV/nucleon 48Ca beam with the intensity of 170 pnA was obtained in December 2008. In the PAC09 presentation, we will summarize our operating experience with the SRC and developments of RIBF accelerators in addition to most up-to-date performance of the RIBF accelerator complex.
*T. Ohnishi et al., J. Phys. Soc. Jpn. 77 (2008) 083201
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
Construction of the DOE Californium Rare Ion Breeder Upgrade (CARIBU) for the ATLAS facility is expected to be completed by the end of 2008 and commissioning should be well along by the time of the conference. The facility will use fission fragments from a 1 Ci 252Cf source, thermalized and collected into a low-energy particle beam by a helium gas catcher, mass analyzed by an isobar separator, and charge breed to higher charge states for acceleration in ATLAS. In addition, unaccelerated beams will be available for trap and laser probe studies. Expected yields of accelerated beams are up to ~5x105 (107 to traps) far-from-stability ions per second on target. The facility design and first results of beam acceleration using a weaker 80 mCi source will be presented in this paper and plans for installation of the 1 Ci source will be discussed.
NSCL, East Lansing, Michigan
The 2007 Long Range Plan for Nuclear Science had as one of its highest recommendations the “construction of a Facility for Rare Isotope Beams (FRIB) a world-leading facility for the study of nuclear structure, reactions, and astrophysics. Experiments with the new isotopes produced at FRIB will lead to a comprehensive description of nuclei, elucidate the origin of the elements in the cosmos, provide an understanding of matter in the crust of neutron stars, and establish the scientific foundation for innovative applications of nuclear science to society.” A heavy-ion driver linac will be used to provide stable beams of >200 MeV/u at beam powers up to 400 kW that will be used to produce rare isotopes. Experiments can be done with rare isotope beams at velocities similar to the driver linac beam, at near zero velocities after stopping in a gas cell, or at intermediate (0.3 to 10 MeV/u) velocities through reacceleration. An overview of the design proposed for implementation on the campus of Michigan State University leveraging the existing infrastructure will be presented.
CIAE, Beijing
TUB, Beijing
To limit the cost for the main magnet of a compact cyclotron CYCIAE-100, the cast steel is used for the top/bottom yoke and return yoke. The imperfection may not be ignored and the harmonic coils on the return yokes will make the fields reaching the requirements easier during the shimming. The centering coils will not only compensate the 1st harmonic fields at the center region, which is usually remain big, but also correct the off-center injection of the beam. The thermal deformation and the vacuum pressure may change the fields distribution during the machine operation and therefore It is necessary to use trim coils to adjust the fields. We arrange the trim coils inside the two opposite valleys of the main magnet. The second harmonics from the trim coils are not big eough to affect the beam dynamics significantly from the beam dynamics study. In this paper, the effects of correction coils of three types are presented. The detail configuration of the correction coils is introduced in the paper as well. One concern is the potential interference of some water cooled coils could have with vacuum. Some experience for the coils inside the high vacuum tank is tested and the results are given.
BNG, Würzburg
GSI, Darmstadt
GSI had manufactured a prototype of a fast cycling superconducting dipole magnet at Babcock Noell GmbH. This is the first full size magnet for the SIS100 synchrotron at the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt / Germany. In close collaboration with GSI, the magnet was technologically developed, manufactured and assembled by Babcock Noell. The system was successfully tested at GSI reaching the nominal cycling performance, including the high ramping rate of 4 T/s and the maximum field of 2.1 T. Especially the superconducting cable, the coils and the iron yoke are subject to strong mechanical and thermal stresses. Here we describe the details on the fabrication of these components and give an outlook on possible improvements of the manufacturing technologies, applicable to future prototypes and series magnets for SIS100.
LBNL, Berkeley, California
Third generation Electron Cyclotron Resonance (ECR) ion sources operate at rf frequencies between 20 and 30 GHz and employ NbTi superconducting magnets with a conductor peak field of 6-7 T. A significant gain in performance can be achieved by replacing NbTi with Nb3Sn, allowing solenoids and sextupole coils to reach a field of 15 T in the windings. In this paper we describe the design of a Nb3Sn superconducting magnet for a fourth generation ECR source operating at a rf frequency of 56 GHz. The magnet design features a configuration with an internal sextupole magnet surrounded by three solenoids. A finite element magnetic model has been used to investigate conductor peak fields and the operational margins. Results of the numerical analysis are presented and discussed.
BNL, Upton, Long Island, New York
PVI, Oxnard
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron clouds have been observed in many accelerators, including RHIC at BNL. They can limit the machine performance through pressure degradation, beam instabilities or incoherent emittance growth. The formation of electron clouds can be suppressed with beam pipe surfaces that have low secondary electron yield. Also, high wall resistivity in accelerators can result in unacceptably high ohmic heating levels for superconducting magnets. These are concerns RHIC, as its vacuum chamber in the superconducting dipoles is made from relatively high resistivity 316LN stainless steel. The high resistivity can be addressed with a copper (Cu) coating; a reduction in the secondary electron yield can be achieved with a titanium nitride (TiN) or amorphous carbon (a-C) coating. Applying such coatings in an already constructed machine is rather challenging. We sta rted developing a robotic plasma deposition technique for in-situ coating of long, small diameter tubes. The technique entails fabricating a device comprising of staged magnetrons and/or cathodic arcs mounted on a mobile mole for deposition of about 5 μm (a few skin depths) of Cu followed by about 0.1 μm of TiN (or a-C).
IMP, Lanzhou
The vacuum system of HIRFL is a large and complex system. HIRFL consists of two ECR ion sources, a sector focus cyclotron (SFC), a separate sector cyclotron (SSC) and a multipurpose cooling storage ring system which has a main ring (CSRm) and an experiment ring (CSRe). Several beam lines connect these accelerators together and transmit various heavy ion beams to more than 10 experiment terminals. According to the requirements of the ion acceleration and ion lifetime, the working pressure in each accelerator is different. SFC is nearly 50 years old. After upgrade, the working pressure in SFC is improved from 10E-6mbar to 10E-8mbar. The pressure in SSC which was built in 1980s reaches the same level. The cooling storage ring system with a length of 500m came into operation in 2007. The average pressure in CSRm and CSRe is 5E-12mbar and 8E-12mbar respectively. Different designs were adopt for vacuum system of dozens beam lines to meet various experiment terminals requirement. For instance, some shockproof measures have to be taken for the heavy ion microbeam facility. A clean and large throughput differential pumping system was built for the Gas-filled Recoil Separator and so on.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The vacuum system of CELLS is in the installation stage. The booster vacuum chambers have been assembled and baked out in a provisional laboratory ex-situ in the ALBA building and in less than two months (starting from February) all the booster vacuum system was installed inside the tunnel and under vacuum. All the storage ring vacuum chambers have been delivered and ready for installation, several chambers were tested at CELLS (tests include vacuum tests, dimensional check, magnetic permeability tests etc). All the tools needed for the assembly of the storage ring vacuum chambers have been delivered and tested at CELLS to validate the assembly procedure. Concerning the standard vacuum components; all the gauges and residual gas analyzers were delivered, all the ion pumps and controllers are at CELLS, the NEG pumps, leak detectors, roughing stations and the UHV valves were delivered too.
CERN, Geneva
In the CERN Large Hadron Collider, about 6 km of the UHV beam pipe are at ambient temperature and serve as experimental or utility insertions. The vacuum of these sectors rely on TiZrV non-evaporable getter (NEG) coating to achieve very low pressure. In the case of venting to atmosphere, the use of NEG coatings implies the bake-out of the vacuum sector to recover the low pressure and reactivate the NEG coatings. A new method to vent a vacuum sector to atmosphere allows performing short interventions without losing completely the performance of the already activated NEG coating. The principle is to over-pressurize the vacuum sector with neon gas which is not pumped by the NEG coatings, remove the faulty component and then pump down the sector again. The injection of such a gas in the vacuum sector aims at preserving the saturation of the NEG coatings during the exchange of the component. A detailed description of this new venting system will be presented and discussed. Preliminary results obtained from a laboratory venting system and its evaluation in the LHC tunnel to replace existing components will be presented.
CERN, Geneva
The LHC collider has recently started-up at CERN. It will provide colliding beams to four experiments installed in large underground caverns. A specially designed and constructed sector of the LHC beam vacuum system transports the beams though each of these collision regions, forming a primary interface between machine and experiment. ATLAS is the largest of the four LHC colliding beam experiments, being some 40 m long and 22 m in diameter. Physics performance, geometry and access imposed a large number of constraints on the design of the beam vacuum system. This paper describes the geometry and layout of the ATLAS beam vacuum system. Specific technologies developed for ATLAS, and for the alignment and installation of the vacuum chambers are described as well as the issues related to the physical interfaces with the experiment.
GSI, Darmstadt
LMU, München
Funding: EU design study, contract 515876, DIRAC-PHASE-1, RP6 SIS 18-2
For the future FAIR facility intensities up to 1012 U28+ ions per second are required. For this purpose the existing heavy ion synchrotron SIS18, which will serve as injector, has to be upgraded. Since the required base pressure is 10-10 Pa, among the different measures undertaken to improve the existing UHV system, the installation of NEG coated magnet chambers is foreseen. Two magnetron sputtering facilities were designed and commissioned at GSI to perform the coating. The characterization of the thin films has been carried out by RBS and XPS. Considering that the vacuum chambers mounted in accelerators undergo several venting-activation cycles, a deep investigation on the NEG aging was performed by ERDA. Fourteen dipole and one quadrupole chambers were coated and installed in the SIS 18, and the replacement of the remaining magnet pipes will follow in the next years. Additionally to overcome the dynamic vacuum instability a collimation system equipped with thin film coated absorbers was successfully tested in 2008. The coating facilities, their operating mode, the results achieved on the thin film characterization, and the ones obtained in the SIS 18 are presented.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
Since the start of the beam commissioning on October 2007, we have succeeded to increase the beam power of the Rapid Cycling Synchrotron (RCS) in the Japan Proton Accelerator Research Complex (J-PARC). The effect of the high power beam on the vacuum had become visible above the beam power of 50 kW. When the high power beam was operated at 25 Hz, the vacuum pressure became higher. Especially the vacuum of the injection area became worse than other areas. The residual gas analyzer was installed in order to investigate which kinds of outgassing were desorbed by the high power beam. The carbon compound mainly increased with the high power beam in the area. The source of the ougtassing is thought to be carbon foils for charge exchange and/or a electron catcher which was installed in order to collect the stripped electron by the carbon foil. After this, the RCS forwards into the stage where the high power beam is continuously operated during a few weeks. We will report the results of the conditioning effect on the vacuum by the beam itself.
BNL, Upton, Long Island, New York
Kyushu University, Hakozaki
IAP, Frankfurt am Main
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A new heavy ion preinjector, consisting of an Electron Beam Ion Source (EBIS), an RFQ, and IH Linac, is under construction at Brookhaven National Laboratory. This preinjector will provide ions of any species at an energy of 2 MeV/u, resulting in increased capabilities for the Relativistic Heavy Ion Collider, and the NASA Space Radiation Laboratory programs. Initial operation of the EBIS and RFQ will be reported on, along with the status of the construction and installation of the remainder of the preinjector.
BNL, Upton, Long Island, New York
Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Work supported by RIKEN.
We have studied a laser ion source in Brookhaven National Laboratory since 2006. In November 2008, we had first beam through an RFQ and the measured current reached about 50 mA with carbon beam. The RFQ and ion source were originally commissioned in Japan and moved to BNL in 2006. We will report various acceleration test results at the conference.
Imperial College of Science and Technology, Department of Physics, London
JAI, Oxford
OXFORDphysics, Oxford, Oxon
For PAMELA project, the injection lay out for both protons as well as carbon 6+ ions is discussed. Injection system would consist of a 30 MeV cyclotron for protons and a chain of elements for carbon ions such as ECR ion source, bending magnets and focusing solenoids; RFQ, IH/CH structures and a striping foils. The charge particle simulation for different protons as well as carbon ions passing through the elements has been carried out with General Particle Tracer (GPT), software.
INFN/LNS, Catania
During the last 10 years it was demonstrated that slight variations of microwave frequency used in ECRIS strongly influence their performances either for extracted current and for beam brightness and stability. Theoretical investigations put in evidence that such frequency tuning is linked to the electromagnetic field structure inside the resonant cavity. On this basis, we carried out PIC simulations, showing that the frequency tuning has a global influence on plasma properties and on beam brightness. Such analysis allowed the design of the optimum setup for plasma chamber dimensions and microwave injection, to achieve higher currents and better emittances. The magnetic field is based on the use of steep gradient but the cryogenics issues are simplified; the extraction system is designed to minimize the aberrations. The overall dimensions of the MISHA source (Multicharged Ion Source for HAdrontherapy) have been chosen as a compromise between the ideal size for microwave to plasma interaction, the need to get long ion confinement time and the request of getting a compact ECRIS. The description of the source design will be given, along with the expected performances.
INFN/LNS, Catania
The trend of ECRIS to higher frequencies and magnetic fields is driven by the need to have higher beam currents and higher charge states for nuclear physics accelerators. Anyway, because of the limits imposed by the magnets’ and microwaves generator’s technology, any further increase of performances requires a detailed investigation of the plasma dynamics. The experiments have shown that the current, the charge states and even the beam shape change by slightly varying the microwave frequency (frequency tuning effect - FTE). Moreover, for last generation ECRIS, electron energies up to 2 MeV have been detected, depending mainly on the magnetic field structure and gradient distribution over the ECR surface. The plasma dynamics have been studied by means of single particle and PIC simulations: they explain the FTE in terms of the wave field distribution over the ECR surface and the existence of high energy electrons due to diffusion in the velocity space above the stochastic barrier. Other methods used to improve the ECRIS performances, e.g. the two frequency heating with an adequate phase relation between the two waves, can be exploited by means of the simulations.
Kyoto ICR, Uji, Kyoto
We are aiming to develop a compact accelerator based neutron source using Li(p,n) reaction. The first target is a small and high current H+ ion source as an injector of the neutron source. The demands are not only being small and high current but also longer MTBF and large ratio of H+ to molecular ions such as H2+ or H3+. Therefore, the ECR ion source with permanent magnets is selected as such an ion source. Because ECR ion sources don't have hot cathodes, longer MTBF is expected. Furthermore, they can provide high H+ ratio because of their high electron temperature. Using permanent magnets makes the ion source small and running cost low. Up to now, we have measured ion beam current on the first model of the ECR ion source, and fabricated the redesigned model. The data measured of the second model will be presented.
LBNL, Berkeley, California
Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
To uniformly heat targets to electron-volt temperatures for the study of warm dense matter, one strategy is to deposit most of the ion energy at the peak of energy loss (dE/dx) with a low (E < 5 MeV) kinetic energy beam and a thin target*. Lower mass ions have a peak dE/dx at a lower kinetic energy. To this end, a small lithium (Li+) alumino-silicate source has been fabricated, and its emission limit has been measured. These surface ionization sources are heated to {10}00-1150 C where they preferentially emit singly ionized alkali ions. Alumino-silicates sources of K+ and Cs+ have been used extensively in beam experiments, but there are additional challenges for the preparation of high-quality Li+ sources: There are tighter tolerances in preparing and sintering the alumino-silicate to the substrate to produce an emitter that gives uniform ion emission, sufficient current density and low beam emittance. We report on recent measurements of high ( up to 35 mA/cm2) current density from a Li+ source. Ion species identification of possible contaminants is being verified with a Wien (E x B) filter, and via time-of-flight.
*J.J. Barnard et al., Nuclear Instruments and Methods in Physics Research A 577 (2007) 275283.
NSCL, East Lansing, Michigan
The National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) is implementing a system to reaccelerate rare isotope beams from projectile fragmentation to energies of about 3 MeV/u. The reacceleration of stopped radioactive beams from projectile fragmentation at the NSCL/MSU makes use of charge state breeding in an Electron Beam Ion Trap (EBIT) to provide a compact and cost efficient system layout of MSU’s ReA3. The MSU EBIT breeder device will provide a high electron beam current density of about 104 A/cm2 making it well suited to rapidly increase the charge state of short-lived isotopes within tens of milliseconds or less. In addition, the breeder is optimized to provide a high storage capacity, a high beam acceptance and uses a continuous injection and beam accumulation scheme explicitly, which makes it unique. To match the beam of singly charged rare isotope ions into the acceptance of the EBIT and to analyze and purify the EBIT beams, a sophisticated beam line and diagnostic system is required. The present paper will present an overview and the status of the ReA3 EBIT.
NSCL, East Lansing, Michigan
Funding: Supported by the National Science Foundation under grant PHY-0110253
The construction of the SUperconducting Source for Ions (SUSI), a 3rd generation Superconducting ECR ion source for the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University has been completed and commissioning of the source is ongoing. SUSI operates primarily at 18GHz and is scheduled to replace the 6.4 GHz SC-ECR for injection in the coupled cyclotron later this year. Excellent performances during commissioning have been obtained with SUSI for the production of highly charged ions for both metallic and gas elements and will be presented. A set of six solenoid coils gives SUSI the capability to modify the length and the position of the resonant zone and also to adjust the gradient of the axial magnetic field near the resonance. The impact of this flexible magnetic field profile on the ion beam production and the charge state distribution is actively studied and will be discussed. Emittance measurements of the ion beam extracted from SUSI have been performed and will also be presented.
Muons, Inc, Batavia
UMD, College Park, Maryland
ORNL, Oak Ridge, Tennessee
Funding: Supported in part by the US DOE Contract DE-AC05-00OR22725
Spallation neutron source user facilities require reliable, intense beams of protons. The technique of H- charge exchange injection into a storage ring or synchrotron can provide the needed beam currents, but may be limited by the ion sources that have currents and reliability that do not meet future requirements and emittances that are too large for efficient acceleration. In this project we are developing an H- source which will synthesize the most important developments in the field of negative ion sources to provide high current, small emittance, good lifetime, high reliability, and power efficiency. We describe planned modifications to the present external antenna source at SNS that involve: 1) replacing the present 2 MHz plasma-forming solenoid antenna with a 60 MHz saddle-type antenna and 2) replacing the permanent multicusp magnet with a weaker electro-magnet, in order to increase the plasma density near the outlet aperture. The SNS test stand will then be used to verify simulations of this approach that indicate significant improvements in H- output current and efficiency, where lower RF power will allow higher duty factor, longer source lifetime, and/or better reliability.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
Funding: The work at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, was performed under contract DE-AC05-00OR2275 for the US Department of Energy.
The U.S. Spallation Neutron Source (SNS) is an accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to insure that we will meet our operational commitments as well as provide for future facility upgrades with high reliability, we have developed an RF-driven, H- ion source based on a ceramic aluminum nitride (AlN) plasma chamber*. This source is expected to enter service as the SNS neutron production source starting in 2009. This report details the design of the production source which features an AlN plasma chamber, 2-layer external antenna, cooled-multicusp magnet array, Cs2CrO4 cesium system and a Molybdenum plasma ignition gun. Performance of the production source both on the SNS accelerator and SNS test stand is reported. The source has also been designed to accommodate an elemental Cs system with an external reservoir which has demonstrated unanalyzed beam currents up to ~100mA (60Hz, 1ms) on the SNS ion source test stand.
*R.F. Welton, et al., “Next Generation Ion Sources for the SNS”, Proceedings of the 1st Conference on Negative Ion Beams and Sources, Aix-en-Provence, France, 2008
ORNL, Oak Ridge, Tennessee
LANL, Los Alamos, New Mexico
Funding: Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory (ORNL), managed by UT-Battelle, LLC for the U. S. Department of Energy
Plasmas produced by helicon wave excitation typically develop higher densities, particularly near the radial plasma core, at lower operating pressures and RF powers than plasmas produced using traditional inductive RF coupling methods. Approximately two years ago we received funding to develop an H- ion source based on helicon wave coupling. Our approach was to combine an existing high-density, hydrogen helicon plasma generator developed at ORNL for the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) project with the SNS external antenna H- source. To date we have achieved plasma densities >1013 e/cm3 inside the ion source using <10kW of RF power and <5 SCCM of H2 gas flow. This report discusses the first cesiated H- beam current extraction measurements from the source.
PPPL, Princeton, New Jersey
HCL, Cambridge, Massachusetts
PU, Princeton, New Jersey
Funding: Research supported by the U.S. Department of Energy.
The evaluation of ion-atom charge-changing cross sections is needed for many accelerator applications. A classical trajectory Monte Carlo (CTMC) simulation has been used to calculate ionization and charge exchange cross sections. For benchmarking purposes, an extensive study has been performed for the simple case of hydrogen and helium targets in collisions with various ions. Despite the fact that the simulations only account for classical mechanics effects, the calculated values are comparable to the experimental results for projectile velocities in the region corresponding to the maximum cross section. Shortcomings of the CTMC method for multi-electron target atoms are also discussed.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
STFC/RAL, Chilton, Didcot, Oxon
The RAL Front End Test Stand (FETS) is being constructed to demonstrate a chopped H- beam of up to 60 mA at 3 MeV with 50 pps and sufficiently high beam quality for future high-power proton accelerators (HPPA). High power proton accelerators with beam powers in the several megawatt range have many applications including drivers for spallation neutron sources, neutrino factories, waste transmuters and tritium production facilities. The aim of the FETS project 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 conditions. This paper details the first results from the initial operation of the ion source.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
The RAL Front End Test Stand (FETS) is being constructed to demonstrate a chopped H− beam of up to 60 mA at 3 MeV with 50 pps and sufficiently high beam quality for future high-power proton accelerators (HPPA). This paper details the mechanical engineering components manufactured so far and the challenges which need to be meet in the near future.
KUK, Abha
KACST, Riyadh
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
At the National Centre for Mathematics and Physics (NCMP), at the King Abdulaziz City for Science and Technology (KACST), Saudi Arabia, a multi-purpose low-energy experimental platform is presently being developed in collaboration with the QUASAR group. The aim of this project is to enable a multitude of low-energy experiments with most different kinds of ions both in single pass setups, but also with ions stored in a low-energy electrostatic storage ring. In this contribution, the injector of this complex is presented. It was designed to provide beams with energies of up to 30 kV/q and will allow for switching between different ion sources from e.g. duoplasmatron to electrospray ion sources and to thus provide the users with a wide range of different beams. We present the overall layout of the injector with a focus on its mechanical and ion optical design.
BNL, Upton, Long Island, New York
AES, Medford, NY
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Gallium arsenide cathodes are used in electron guns for the production of polarized electrons. In order to have a sufficient quantum efficiency lifetime of the cathode the vacuum in the gun must be 10-11 torr or better, so that the cathode is not destroyed by ion back bombardment. All successful polarized guns are DC guns, because such vacuum levels can not be obtained in normal conducting RF guns. A superconductive RF gun may provide a sufficient vacuum level due to cryo-pumping of the cavity walls. We report on the progress of our experiment to test such a gun.
BNL, Upton, Long Island, New York
A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the RF field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.
Tech-X, Boulder, Colorado
Funding: Supported by the US DOE Office of Science, Office of Nuclear Physics under grants DE-FC02-07ER41499 and DE-FG02-08ER85182; used NERSC resources under grant DE-AC02-05CH11231.
Novel electron-ion collider (EIC) concepts are a high priority for the long-term plans of the international nuclear physics community. Orders of magnitude higher luminosity will be required for the relativistic ion beams in such accelerators. Electron cooling is a promising approach to achieve the necessary luminosity. The coherent electron cooling (CEC) concept proposes to combine the best features of electron cooling and stochastic cooling, via free-electron laser technology, to cool high-energy hadron beams on orders-of-magnitude shorter time scales*. In a standard electron cooler, the key physical process is dynamical friction on the ions. The modulator section of a coherent cooler would be very similar to a standard cooler, but in this case dynamical friction becomes irrelevant and the key physics is the shape of the density wake imprinted on the electron distribution by each ion. We will present results using the massively parallel VORPAL framework for both particle-in-cell (PIC) and molecular dynamics (MD) simulations of electron-ion collisions in relativistic coolers and CEC modulators.
* V.N. Litvinenko, I. Ben-Zvi, M. Blaskiewicz, Y. Hao, D. Kayran, E. Pozdeyev, G. Wang, G.I. Bell, D.L. Bruhwiler, A.V. Sobol et al., FEL Conf. Proc. (2008), in press.
ANL, Argonne
Several high power proton and ion linac projects based on superconducting accelerating technology are currently under study and drive an important worldwide R&D effort on superconducting cavities, especially for low and medium energy linacs. Multi-cell elliptical cavities, single or multi-spoke cavities, half-wave and quarter-wave superconducting cavities have been developed at many laboratories and institutions and continue to extend the state-of-the-art for this class of cavities. This talk reviews recent developments and results for SC cavity performance along with a brief overview of associated components such as mechanical slow tuning systems, fast tuners and rf power couplers.
GSI, Darmstadt
The effect of space charge on the transverse Schottky spectrum of coasting and bunched beams is studied using measurements and simulations together with analytic models. The measurements of transverse Schottky bands from heavy ion beams are performed in the SIS-18 synchrotron at GSI. In addition we analyze the noise spectrum from a particle tracking code with self-consistent space charge. Both results are compared to analytic models for coasting and for bunched beams with space charge. For coasting beams an analytic model based on the transverse dispersion relation with linear space and chromaticity reproduces the characteristic deformation of Schottky bands with increasing space charge, observed in both measurement and simulation. For bunched beams we find good agreement between the observed shifts of synchrotron satellites and a simplified model for head-tail modes with space charge. The relevance of the results for the analysis of transverse beam stability in the presence of space charge is emphasized.
NSCL, East Lansing, Michigan
BNL, Upton, Long Island, New York
Funding: this work is supported by National Science Foundation Grant PHY-0606007.
The Small Isochronous Ring (SIR) at the NSCL/MSU was built to study space charge effects in the isochronous regime. Results of experimental studies of the longitudinal beam dynamics in the ring showed a remarkable agreement with results of numerical simulations. Recently, we have designed and built an energy analyzer to accurately measure the beam energy spread. We will present results of energy spread measurements as well as simulations of the beam behavior based on the Vlasov formalism.
ANL, Argonne
GANIL, Caen
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
We have developed and tested an X-ray based Bunch Length Detector (XBLD) for application in ion accelerators. X-rays produced as a result of ion beam interactions with matter are used to generate photoelectrons. The photoelectrons are analyzed by an rf deflector synchronized with the master oscillator, similar to the BLDs based on secondary electrons. The expected time resolution is several picoseconds. The proposed XBLD is particularly useful for the measurement of cw heavy-ion beams passing through a stripper foil or film in a high-power driver accelerator. The results of the XBLD commissioning and beam bunch profile measurements at the ANL heavy-ion cw ATLAS accelerator will be presented.
ANL, Argonne
IIT, Chicago, Illinois
Tech-X, Boulder, Colorado
Funding: DOE. OHEP
We are modeling breakdown arcs in rf structures with Particle in Cell, (OOPIC Pro and VORPAL), Molecular Dynamics (HyDyn, LAMMPS), and an integrated radiation-magnetohyrodynamic package (HEIGHTS) to evaluate the basic parameters and mechanisms of rf discharges. We are evaluating the size, density, species temperature, radiation levels and other properties, to determine how the breakdown trigger works, what the growth times of the discharge are, effects of strong magnetic fields and what happens to both the arc and cavity energy. The goal is to have a complete picture of the plasma and its interaction with the wall. While we expect that these calculations will help guide further experimental studies, we have recently benchmarked model predictions against available experimental data on rise times of x ray pulses, and found a reasonable agreement.
CERN, Geneva
Electrical breakdown in the accelerating cavities set a potential limit to the performance of the CLIC linear collider. Vacuum degradation and beam instability are possible outcomes from a breakdown if too much gas is released from the cavity surface. Quantitative data of gas release are provided for copper electrodes (milled Cu-OFE, as-received and heat-treated), and molybdenum electrodes. These data are produced from a controlled DC spark environment with capacitance charged anode at fixed energy.
Far-Tech, Inc., San Diego, California
The fixed-field alternate gradient (FFAG) synchrotron offers an attractive solution for systems that require rapid acceleration over a wide range of energies. The ability to rapidly tune the frequency of the accelerating cavity in the “non-scaling” variety of an FFAG synchrotron represents a fundamental barrier to their implementation in a wide variety of applications for proton, ion and muon acceleration. Initial results of the rapidly tunable cavity design for specific application to proton and light ion medical FFAG accelerators are presented.
GSI, Darmstadt
To feed the production targets of FAIR with very short bunches (pulse durations of not more than 50 ns are envisaged) demanding rf-systems for bunch compression are required in SIS18 and SIS100. But also the opposite process, namely debunching, is required in the collector ring CR. Bunch compression as well as debunching will be done by fast bunch rotation. Due to space restrictions both rf-systems must be able to generate a very high field gradient of 50 kV/m at very low frequencies. Such high field gradients can be realised only using magnetic alloy (MA) cavities, since their saturation field strength is about ten times higher compared to NiZn-ferrites. For SIS18 a MA bunch compressor unit, which generates the required 50 kV/m at 800- and 1200 kHz, has already been realized as a forerunner for the required FAIR-systems.
CEA, Gif-sur-Yvette
GANIL, Caen
LPSC, Grenoble
The Spiral2 project at Ganil aims at producing exotic ion beams for Nuclear Physics. The accelerator of the primary beam is a superconducting LINAC designed to provide 5mA deuteron beams at 40MeV. It will also allow accelerating stable ions of different Q/A values ranging from protons to Q/A=1/6 heavy ions. The accelerator should be commissioned by the end of 2011, first beam in 2012; the first tests aiming to produce exotic beams are planned one year later. The superconducting LINAC consists of 12 low beta (0.07) quarter wave (88MHz) superconducting (SC) cavities and 24 beta (0,14) SC cavities integrated in their cryomodule. The status of the low beta cryomodules, supplied by the CEA Saclay Irfu institute, is reported in this paper. The RF full power tests were performed at the end of 2008 on the qualifying cryomodule, and the tests of the first series cavity in vertical cryostat were performed during spring 2009.
KEK, Ibaraki
KAKEN Inc., Mito
Sokendai, Ibaraki
In order to achieve higher and more stable performance of super conducting radio-frequency (SRF) cavities, extensive effort in development and application has been done for surface treatment and conditioning methods. Those methods have been evaluated with vertical tests showing lots of remarkable results in cavity performance. However it cannot be well understood yet how surface treatment or conditioning contributed to the results and which step of process in the treatment or conditioning affected the results. In this article, we describe our try to understand those questions focusing on the surface analyses with scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) for electro-polishing (EP) processed niobium sample coupons.
KEK, Ibaraki
JLAB, Newport News, Virginia
The Electro-polishing process is the best candidate of final surface treatment for the production of ILC cavities. Nevertheless, the broad distribution of the gradient caused by field emitters in cavities is sitll a serious problem for the EP process. Ethanole- and degreaser-rinse processes after the EP process were found to be effective to decrease the field emmitter in recent studies, however, these are not perfect yet. We tried to test the sponge cleaning as the post EP process to remove the field emitter inside the cavcity. This article describe the results of series tests with a proto-type sponge-cleaning tool for single-cell cavity at KEK.
LBNL, Berkeley, California
UCB, Berkeley, California
Funding: This work was supported by the Director, Office of Science, Office of High Energy and Nuclear Physics, Division of Nuclear Physics of the US Department of Energy under Contract No. DE-AC02-05CH11231.
A RF system of 500W - 10.75 to 12.75 GHz was designed and integrated into the Advanced Electron Cyclotron Resonance (AECR) ion source of the 88-inch Cyclotron at Lawrence Berkeley National Laboratory. The AECR produces ion beams for the Cyclotron giving large flexibility of ion species and charge states. The broadband frequency of a Traveling Wave Tube (TWT) allows modifying the shape of the annular ellipsoidal-shaped volume that couples and heats the plasma. Details of the RF source and Automatic Gain Control Unit designs for the TWT and integration with the AECR source are provided.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The SNS has been operational and delivering beam to the target for 3 years. Over this time period we have increased the beam power delivered to the target to 700 kW, 50% of the design goal. The RF Group has acquired a fair amount of experience in the operation and maintenance of our RF systems during the power ramp up process. This paper reviews the design and layout of the various SNS RF systems, documents the present state and performance of the systems and covers, in a broad sense, issues raised during operation and improvements we have undertaken as well as future RF system requirements.
BESSY GmbH, Berlin
PTB, Berlin
Funding: Work funded by Physikalisch-Technische Bundesanstalt
The Metrology Light Source (MLS) [1] is in user operation since 2008 at operating energies ranging from 105 MeV up to 630 MeV and with multi bunch currents up to 200 mA. At the injection energy of 105 MeV as soon as the beam current exceeds a few mA, the beam is strongly blown up in all three spatial dimensions and strong oscillations at very different spectral frequencies can be observed. These effects are caused by the interaction of beam charge with ions present and their strength and characteristic time scales depend on several machine parameters. As ion effects can strongly deteriorate the performance of the MLS, we report on first investigations.
CNAO Foundation, Milan
INFN/LNF, Frascati (Roma)
The Centro Nazionale di Adroterapia Oncologica (National Center for Oncological Hadrontherapy, CNAO) is the Italian center for deep hadrontherapy. It will deliver treatments with active scanning both with proton and carbon ion beams. The accelerator complex is based on a 25 m diameter synchrotron capable to accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV. Four treatment lines, in three treatment rooms, are foreseen in a first stage. In one of the three rooms a vertical and a horizontal fixed beam lines are provided, while in the other two rooms the treatment will be administered with horizontal beams only. The injection chain is positioned inside the synchrotron ring itself, to save space and to better exploit the two non-dispersive regions in the synchrotron. The injection chain is made by a 8 keV/u Low Energy Beam Transfer line (LEBT), a RFQ accelerating the beam to 400 keV/u, a LINAC to reach the injection energy of 7 MeV/u and a Medium Energy Beam Transfer line (MEBT) to transport the beam to the synchrotron. This report describes the design and the performances of the CNAO complex, and reports about the status of the commissioning of the machine.
ITEP, Moscow
All known ion beam transport systems for medical applications with or without GANTRY are very large, complicated and expensive. Its cost is comparable with accelerator facility itself. It stimulates search of beam transport and distribution systems that allow reducing their cost and sizes considerably keeping treatment efficiency. Two such transport system are considered in the present paper. The first one is based on bend magnets that are rotated around their center of mass with movement of patient in horizontal position around of magnets. The second one uses stationary magnets with movement of patient in horizontal position in vertical plane. It is shown that the proposed ion transport systems provide treatment efficiency comparable with GANTRY at considerably lower sizes, mechanical complexity and cost.
INFN/LNS, Catania
The study of the Superconducting Cyclotron named SCENT300 [1] was carried out by the accelerator R&D team of LNS-INFN of Catania in collaboration with the University of Catania and supported by IBA (Belgium). The new design features concerning the magnetic properties of the machine and the last results about the beam dynamic are presented.
JAEA, Tokai-mura
JAEA/Kansai, Kyoto
Toshiba, Tokyo
Kyoto ICR, Uji, Kyoto
Hokkaido University, Sapporo
The cancer treatment with hadron beams continues to be made as hadron treatment facilities are being developed around the globe with state-of-the-art accelerator technology. The generation of energetic protons and ions from laser-plasma interactions, has made laser-driven hadron radiotherapy a subject of strong interest. Proton bunches with high peak current and ultralow emittance are typical of ultrafast laser-foil interactions. However, these bunches also exhibit large divergence and energy spread. Photo Medical Research Center (PMRC) of JAEA was recently established to address the challenge of the laser-driven ion accelerator development for hadron therapy. Our mission at PMRC is to develop integrated, laser-driven ion accelerator systems (ILDIAS) that demonstrate desired beam characteristics for such therapy. We used the Phase and Radial Motion in Ion Linear Accelerators (PARMILA) design software which was originally developed as a numerical tool to design and simulate beam performance. This report will discuss beam specifications of laser-driven ion accelerators using PARMILA.
NIRS, Chiba-shi
AEC, Chiba
A 3D scanning method gated with patient's respiration has been developed for the HIMAC new treatment facility. In the scanning irradiation, the RF-KO slow-extraction method has been used, because of the quick response to beam on/off from the synchrotron. However, a small amount of beam remained just inside the separatrix is extracted just before turning on the transverse RF field, which brings the extra dose. We proposed to apply another transverse RF-frequency component matched with the betatron frequency of the particles in the vicinity of the stopband, in addition to the original transverse RF field for the RF-KO slow-extraction. Using the proposed method, the particles just inside the separatrix, which cause the extra dose, can be selectively extracted during the irradiation; as a result, the extra dose can also be reduced. The validity of this approach has been verified by the simulation and the measurement with the non-distractive 2D beam profile monitor. We will report the result of this approach.
Siemens Med, Erlangen
Siemens DK, Jyllinge
Siemens has earned two contracts to deliver Particle Therapy* systems to be operated in Marburg and Kiel, both in Germany. The accelerator consists of an injector (7 MeV/u protons and light ions) and a compact synchrotron able to accelerate proton beams up to 250 MeV and carbon ions up to 430 MeV/u. These beams can be slowly extracted and delivered to a choice of fixed-angle horizontal, semi-vertical and vertical beam-ports. An overview of the design will be given. At the time of PAC09 installation of the first system will be nearing completion and commissioning will have started. Performance of some of the components and the status of the projects will be presented.
*Particle Therapy is a work in progress and requires country-specific regulatory approval prior to clinical use.
UCBL, Villeurbanne
IN2P3 IPNL, Villeurbanne
DIAM is a new experimental system created for study the processes initiated by protons impact upon clusters of biomolecules especially the mechanism resulting from ionization and fragmentation in a complex molecular nanosystem. The experimental setup is designed to analyse interactions of two beams: on the one hand, protons from an ECR source are accelerated and guided into a monochromatic beam of 20 to 150 kV and 1mA. On the other hand, a cluster source is mounted on a high tension plat-form (5 to 30 kV). In order to analyse the products of protons/cluster interaction of the 2 crossing beams, we use several detection system such as Electro spray Time of Flight (ESI-TOF) or mass spectrometers.
LBNL, Berkeley, California
Funding: This work was supported by DOE and NSA.
The integration of scanning probes with ion beams enables non-destructive, nanometer scale imaging and alignment of ion beams to regions of interest in to be implanted device structures. We describe our basic approach which uses piezo-resistive force sensors and pierced cantilvers as dynamic shadow masks, integtrated with low current (<1 mA), low energy (<1 MeV) ion beams from a series of ion sources (ECR and EBIT). Single ion sensing strategies based on charge transients induced in devices and detection of secondary electrons are discussed. We will show results form our studies of single ion doping of 50 nm scale transistors in tests of radiation response mapping of transistors with this technique.
UOR, Jaipur
IUAC, New Delhi
Swift Heavy Ion (SHI) induced modification at Metal/Si interfaces has emerged as an interesting field of research due to its large applications. In the present study we investigate SHI induced mixed molybdenum silicide film with ion fluences. The Molybdenum and Si thin thin films were deposited on Silicon substrates using e-beam evaporation at 10-8 torr vacuum. Thin films were irradiated with Au ions of energy 120 MeV to form molybdenum silicide. The samples were characterized by grazing incidence X-ray diffraction (GIXRD) technique for the identification of phase formation at the interface. Rutherford backscattering spectrometry (RBS) was used to investigate the elemental distribution in the films. The mixing rate calculations were made and the diffusivity values obtained leads to a transient melt phase formation at the interface according to thermal spike model.
USTC/NSRL, Hefei, Anhui
Funding: Work supported by National Natural Science Foundation of China (No.10175062 & 10575100).
In recent years, Fixed Field Alternating Gradient (FFAG) accelerator is becoming a highlight in particle accelerator R&D area. This type of accelerator could accelerate ions with higher beam current than conventional strong focusing circular accelerator, which could be more useful for the study of radioactive material. In this paper, conceptual design of an FFAG with high Helium ion beam current and a few MeV energy which is dedicated to study the impact of Helium embitterment to fusion reactor envelope material is discussed, the periodic focusing structure model is given, following which the calculation result of magnetic field is also presented.
GSI, Darmstadt
Laboratoire de Physique des Gaz et des Plasmas, Universite Paris-Sud, Orsay
IPCP, Chernogolovka, Moscow region
TU Darmstadt, Darmstadt
Universidad de Castilla-La Mancha, Ciudad Real
Studies of High Energy Density (HED) states in matter is one of the recently proposed important applications of intense particle beams. GSI Darmstadt is worldwide famous due to its unique accelerator facilities. Construction of the new accelerator FAIR, will enhance these capabilities many fold. During the past years, extensive theoretical work has been carried out to propose future HED physics experiments that could be carried out at FAIR. It is expected that the new heavy ion synchrotron, SIS100, will deliver a uranium beam with 1012 uranium ions that will be delivered in a single bunch, 50 – 100 ns long. Circular, elliptic and annular focal spots can be generated that will allow one to perform different type of HED physics experiments. This work has shown that using a special technique, named HIHEX, one may access those areas of the phase diagram that have never been accessed before. Using another experimental configuration, LAPLAS , it will be possible to generate physical conditions that are expected to exist in the interiors of the giant planets. Material properties under dynamic conditions can also be studied using a third experimental set up.
LBNL, Berkeley, California
Funding: This work is supported by NA22 of NNSA under the Department of Energy contract No. DE-AC02-05CH11231.
Active neutron interrogation has been demonstrated to be an effective method of detecting shielded fissile material. A fast fall-time/fast pulsing neutron generator is needed primarily for differential die-away technique (DDA) interrogation systems. A compact neutron generator, currently being developed in Lawrence Berkeley National Laboratory, employs an array of 0.25-mm-dia apertures (instead of one 5-mm-dia aperture) such that gating the beamlets can be done with low voltage and a small gap to achieve sub-microsecond ion beam fall time and low background neutrons. The system will aim at both high and low beam current applications. We have designed and fabricated an array of 16 apertures (4x4) for a beam extraction experiment. Our preliminary results showed that, using a gating voltage of less than 800 V and a gap distance of 1 mm, the fall time of extracted ion beam pulses is less than 1 ms at various beam energies ranging between 200 eV to 600 eV. More experimental results with an array of 20×20 apertures will be presented.
NCC, Korea, Kyonggi
SNU, Seoul
An accelerator mass spectrometer (AMS) based on a compact cyclotron has been studied for biomedical uses. The system will have the mass resolving power of over 4000 to analyze a few different kinds of isotopes for tracing or chronometric dating. High transmission efficiency is a major design goal to compete with a Tandem AMS. A compact magnet with high stability, a saw tooth harmonic buncher, and flat-topping rf system are the components needed to achieve the goal. The results of design study for the AMS cyclotron and its injection line will be presented as well as the results of model tests for the cavity and the buncher.
CERN, Geneva
The PS2 is proposed as a replacement for the ageing PS and will provide proton beams with kinetic energies up to 50 GeV. It must also deliver Pb54+ ions, for which the revolution frequency swing will be more than a factor of two. The favoured rf scenario considers a 40 MHz accelerating system and is motivated by the possibility of chopping at up to 40 MHz in the SPL, the proposed proton injector. Using the same principal rf system for ions implies pushing for an unprecedented tuning range and the introduction of a new rf system in LEIR, the existing ion source. We present a solution to the disparate requirements of protons and ions based on a 40 MHz rf system with switchable tuning ranges to cover the large frequency swing required.
GSI, Darmstadt
In order to achieve the goals of the FAIR project, the heavy ion beam intensities have to be increased by two orders of magnitude. Space charge limits and significant beam loss in stripper stages disable a continuation of the present high charge state operation. However, in the energy range of SIS18 and SIS100, the chosen intermediate charge state for uranium 28+, is lower than the equilibrium charge state. Thus ionisation processes due to collisions with rest gas atoms become the main issue with respect to potential beam loss. Therefore, the SIS100 design concept is focused on the goal to minimization the beam-rest gas interaction and consequently the beam loss by charge change: SIS100 is the first synchrotron which has been optimised for the acceleration of intermediate charge state heavy ion operation. Ionisation beam loss, desorption processes and pressure stabilization were the driving issues for the chosen system layout and for several technological approaches. Beside focusing the SIS100 design on this specific issue an extended upgrade program is actually being realized to accommodate SIS18 for the intermediate charge state booster operation.
BNL, Upton, Long Island, New York
Funding: Department Of Energy
Under certain assumptions and simplifications, we studied a few physics processes of Coherent Electron Cooling using analytical approach. In the modulation process, the effect due to merging the ion beam with the electron beam is studied under single kick approximation. In the FEL amplifier, we studied the amplification of the electron density modulation using 1D analytical approach. Both the electron charge density and the phase space density are derived in the frequency domain. The solutions are then transformed into the space domain through Fast Fourier Transformation (FFT).
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Antiprotons in Fermilab’s Recycler ring are cooled by a 4.3 MeV, 0.1A DC electron beam as well as by a stochastic cooling system. In this paper we will describe electron cooling improvements recently implemented: adjustments of electron beam line quadrupoles to decrease the electron angles in the cooling section and a better stabilization and control of the electron energy.
Fermilab, Batavia
MSU, East Lansing, Michigan
TRIUMF, Vancouver
PAC, Batavia, Illinois
UCR, Riverside, California
The quest for higher beam power and duty factor and precisely controlled beams at reasonable cost has generated world-wide interest in Fixed-field Alternating Gradient accelerators (FFAGs). A new concept in non-scaling FFAGs to stabilize the betatron tune is under development. The emphasis to date has been on electron and proton accelerators, yet many facilities utilize H- front ends. This concept naturally extends to H- FFAGs and under conditions of rapid acceleration, the FFAG functions essentially as a recirculating linac with a common-aperture arc. As such it may be suitable for replacement of aging H- linac sections. For a slow acceleration cycle, an H- FFAG machine can exploit H- techniques to control extraction and intensity, and represents an innovation in proton therapy accelerators. Prototype RF and magnet component design have been initiated. For ten-turn acceleration, the rf cavities in a 10-100 MeV FFAG cannot be re-phased on the revolution time scale, and local adjustment of the pathlength is the proposed approach. For slow acceleration, broad-band, low-frequency rf can be applied. The basic optics and components for such FFAGs are presented.
UCLA, Los Angeles, California
Instituto Superior Tecnico, Lisbon
Funding: Fundacao Calouste Gulbenkian and Fundacao para a Ciencia e Tecnologia under grants SFRH/BD/35749/2007.
The possibility of using a CO2 laser (10 micron wavelength) to drive a plasma density compression and achieve effective ion acceleration in gaseous targets (density>~ 1019cm-3) is explored. A parameter scan is performed with a set of particle in cell simulations in OSIRIS*, both in 2D and 3D, for various laser intensities, linear/circular polarization pulses, and plasma densities. Results show that, to generate the shock compression, plasma density must be increased above the critical value to account for the relativistic motion of the electrons. Under these conditions, 2-5MeV ions are observed with moderate intensity (a0=3) laser pulses. Finally, configurations to generate a shock structure are suggested, that will more efficiently accelerate the particles. This scenario is also of particular relevance to fast-ignition, inertial confinement fusion, and implications to those regimes can be obtained from numerical simulations by using the appropriate density normalization.
*R. A. Fonseca et al, LNCS 2329, III-342, Springer-Verlag, (2002)
LBNL, Berkeley, California
PPPL, Princeton, New Jersey
Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Recent changes to the NDCX beamline offer the promise of higher current compressed bunches, with correspondingly larger fluences, delivered to the target plane for ion-beam driven warm dense matter experiments. We report modeling and commissioning results of the upgraded NDCX beamline that includes a new induction bunching module with approximately twice the volt-seconds and greater tuning flexibility, combined with a longer neutralized drift compression channel.
LBNL, Berkeley, California
LLNL, Livermore, California
Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Longitudinally compressed ion beam pulses are currently employed in ion-beam based warm dense matter studies. Compression arises from an imposed time-dependent longitudinal velocity ramp followed by drift in a neutralized channel. Chromatic aberrations in the final focusing system arising from this chirp increase the attainable beam spot and reduce the effective fluence on target. We report recent work on fast correction optics that remove the time-dependent beam envelope divergence and minimizes the beam spot on target. We present models of the optical element design and predicted ion beam fluence, as well as benchtop measurements of pulsed waveforms and response.
LLNL, Livermore, California
TomoTherapy, Madison
CPAC, Madison
Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We are developing a compact proton accelerator for cancer treatment by using the dielectric high-gradient insulator wall technology. The goal is to fit the compact dielectric wall proton therapy machine inside a conventional treatment room. To make the proton dielectric wall accelerator (DWA) compact requires a compact proton source capable of delivering protons in a sub-ns bunch. We are testing all the essential DWA components, including the compact proton source, on the First Accelerator System Test (FAST), which is designed to be taken apart and rebuilt many times to increase system performance by using improved components. The proton source being investigated currently is a surface flashover source. Five induction cells with HGI in the acceleration gaps are used to provide the 300-keV, 20-ns injector voltage for the proton injector. The physics design and the configuration of the injector and FAST will be presented.
Nagaoka University of Technology, Nagaoka, Niigata
University of the Thai Chamber of Commerce, Bangkok
TIT, Yokohama
KEK, Ibaraki
The KEK digital accelerator (KEKDA), which is an injector-free induction synchrotron capable of accelerating any ions with their possible charge state, is under construction*. This machine is an interesting device as a driver to explore a Warm Dense Matter (WDM) state. The irradiation onto a target at a small focal spot (< a few mm) with a short pulse duration (< 100 nsec) is required to create an interesting WDM state. The target temperature based on an equation-of-state fitted from SESAME table data is estimated as a function of the focal spot size and the ion number per bunch. Final focusing of an ion beam bunch extracted from KEKDA is realized through a half mini-beta system. For this purpose, the beamline has been carefully designed. Beam parameters, such as Twiss parameter, and the guiding magnet parameters will be given together with the drawing of the beamline.
*T. Adachi et al., “Modification of the KEK PS-Booster as a Digital Accelerator”, in this conference.
PPPL, Princeton, New Jersey
Funding: Research supported by the U. S. Department of Energy.
This paper presents a survey of the present theoretical understanding based on advanced analytical and numerical studies of collective interactions and instabilities for intense one-component ion beams, and for intense ion beams propagating through background plasma. The topics include: discussion of the condition for quiescent beam propagation over long distances; the electrostatic Harris instability and the transverse electromagnetic Weibel instability in highly anisotropic, one-component ion beams; and the dipole-mode, electron-ion two-stream instability (electron cloud instability) driven by an unwanted component of background electrons. For an intense ion beam propagating through a charge-neutralizing background plasma, the topics include: the electrostatic electron-ion two-stream instability; the multispecies electromagnetic Weibel instability; and the effects of a velocity tilt on reducing two-stream instability growth rates. Operating regimes are identified where the possible deleterious effects of collective processes on beam quality are minimized.
PPPL, Princeton, New Jersey
LBNL, Berkeley, California
Funding: Research Supported by US Department of Energy.
Plasma are a source of unbound electrons for charge netralizing intense heavy ion beams to focus them to a small spot size and compress their axial length. To produce long plasma columns, sources based upon ferroelectric ceramics with large dielectric coefficients have been developed. The source utilizes the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) is covered with ceramic material. High voltage (~8kV) is applied between the drift tube and the front surface of the ceramics. A BaTiO3 source comprised of five 20-cm-long sources has been tested and characterized, producing relatively uniform plasma in the 5x1010 cm-3 density range. The source has been integrated into the NDCX device for charge neutralization and beam compression experiments. Initial beam compression experiment yielded current compression ratios ~ 120. Recently, an additional 1 meter long source was fabricated to produce a 2 meter source for NDCX compression experiments. Present research is developing higher density sources to support beam compression experiments for high density physics applications.
GSI, Darmstadt
The FAIR heavy ion synchrotrons SIS100/300 will provide heavy ion and proton beams with variable time structure. Fast extraction of compressed single bunches from SIS100, fast beam transfer between SIS100 and SIS300 and slow extraction from SIS100 and SIS300 will be provided. High average beam intensities and the generation of an uninterrupted linac-like beam are enabled by combining both heavy ion synchrotrons in different operation modes (fast acceleration and stretcher operation). In order to reduce beam loss at slow extraction of intense heavy ion beams and to minimize the beam load in subsequent accelerator structures, dedicated ion optical settings of the basic lattice functions and higher order corrections will be applied. However, the tight geometrical constraints in the rather short straight sections and the need to extract from both synchrotrons, fast and slow, at the same position and in parallel to the beam transport system, require operation parameters of the extraction devices close to the limits of technical feasibility. Higher order beam dynamics simulations and technical developments will be presented.
ORNL, Oak Ridge, Tennessee
Funding: *SNS is managed by UT-Battelle, LLC, for the U. S. Department of Energy under Contract No. DE-AC05-00OR22725.
Thin carbon foils used as a charge strippers for H־ ions have a limited life time and produce uncontrolled beam loss. Thus, foil based injection is one of the factors limiting beam power in high intensity proton rings. There is a possibility to replace such foils by laser-assisted stripping of negative hydrogen ions, a method developed and demonstrated at the SNS accelerator in Oak Ridge. In this paper we present progress in the physics and computation of H־ laser stripping. We present a physical model which includes such factors as the Stark effect, the polarization of the laser field, and the spontaneous relaxation and autoionization of hydrogen atoms in a strong electro-magnetic field. The model formulates a quantum mechanical problem that can be solved numerically using a module created for the PyORBIT parallel code developed at SNS.
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The development of a uniform and stable high velocity, thin liquid lithium film stripper is essential for the Facility for Rare-Isotope Beams (FRIB) Project. The formation of such a film has been demonstrated recently at ANL. Film thickness should be measured, and its temporal and spatial stability under high power ion beam irradiation should be verified. Intense beams of light ions generated by the FRIB prototype injector can be used for this task. The injector consists of an ECR ion source followed by a LEBT. A DC 3.3 mA/75 kV proton beam has been generated at the LEBT output. Proton beam power will be brought to required level by adding the second acceleration tube. A low energy electron beams (LEEB) technique, based on the thickness-dependent scattering of the electrons by the film, has been proposed as a fast-response on-line film thickness monitoring. A LEEB test bench has been built to verify this technique. The transmission of electrons through the carbon foils of different thicknesses was measured and compared with results of CASINO simulations. Agreement between the experimental and numerical results allows quantitative measurements of film thickness using the LEEB.
KEK, Ibaraki
Thick carbon foils (>300 ug/cm2)has been used for stripping of H- ion beam at the 3GeV Rapid Cycling Synchrotron (3GeV-RCS) of J-PARC, where foils with long lifetime against high temperature >1800 °K are strongly required for efficient accelerator operations. The key parameter to the foil lifetime is foil temperature attained during irradiation. We have recently developed a new irradiation system for lifetime measurement using the KEK 650 keV Cockcroft-Walton accelerator with high current pulsed and dc H- beam, which can simulate the high-energy depositions upon foils in the RCS. During irradiation tests by this system, the temperature of foil is measured by a thermometer in a dc mode, and by using a photo-transistor in a pulsed mode. This paper describes the pulsed measurements with 5-10 mApeak, 0.1-0.5 msec duration and 25 Hz repetition.
JAEA, Ibaraki-ken
RIST, Ibaraki
NSCL, East Lansing, Michigan
Funding: The funding information for R.M. Ronningen is U.S. Department of Energy Grant Number DE-FG02-08ER41548.
The Particle and Heavy Ion Transport Code (PHITS)* has been typically used to predict radiation levels around high-energy (above 100 MeV/u) heavy-ion accelerator facilities. However, predictions of radiation levels around low-energy (around 10 MeV/u) heavy-ion facilities are also desirable, but the reliability of PHITS at low energies has not been investigated. In this work, neutron energy spectra from 10 MeV/u 12C and 16O ions incident on C and Cu targets have been calculated using the quantum molecular dynamics (QMD) model coupled to the generalized evaporation model (GEM) in PHITS. In particular, the influence of the “switching time”, defined as the time when the QMD calculation is stopped and the calculation switches to the GEM model, was studied. The calculated neutron energy spectra obtained using a value of 100 fm/c for the switching time agree well with the experimental data. We have also used PHITS to simulate an experimental study by Ohnesorge et al.**, by calculating neutron dose equivalent rates, for 3-16 MeV/u 12C, 16O and 20Ne beams incident on Fe, Ni and Cu targets. The calculated neutron dose equivalent rates agree well with the data.
*H. Iwase, K. Niita and T. Nakamura, J. Nucl. Sci. Technol. 39, 1142 (2002).
**W.F. Ohnesorge, H.M.Butler, C.B.Fulmer and S.W.Mosko, Health Physics 39, 633 (1980).
CERN, Geneva
The PS2 will replace the present CERN-PS as the LHC pre-injector. It will have twice the PS energy and twice the circumference. Extensive design optimization is presently ongoing with the aim of starting the PS2 construction around 2011 and delivering beams for physics in 2017. The talk describes the various PS2 design constraints, the optimization steps, and the path towards the final design.
RIKEN Nishina Center, Wako
Significant progress has been achieved since first ECR ion source was developed more than three decades ago and it became one of the best ion sources for heavy ion accelerators in the world. Such progress has been mainly due to utilization of higher microwave frequency and stronger magnetic confinement, technical innovations, and understanding of the production mechanisms of highly charged heavy ions in ECR plasma. Especially, in the last decade, the progress is strongly dependent on advances in the superconducting magnet technology and understanding of the Physics of ECR plasma. Very recently, as the interest in the radioactive beam for research in various fields grows, the need for more intense beam of highly charged heavy ions to inject into the accelerator requires new innovation to improve the ECR ion source performance. In this contribution, I will present the progress of the technology and physics of ECR ion sources. Based on these results, the concepts for next generation ECR ion source for meet the requirements will be presented.
ORNL RAD, Oak Ridge, Tennessee
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Over the past year the performance of the LBNL H- source has been improved to routinely produce 36 mA when averaged over 0.7 ms long pulses at 60 Hz, measured at the RFQ output of the Spallation Neutron Source accelerator. This is up from 25-30 mA during early 2008, and up from {10}-20 mA during 2007. Some of the recent gain was achieved with refined conditioning and cesiation procedures, which now yield peak performance within 8 hours of starting a source change. The ~10 mg released Cs is sufficient for 3 weeks of operation without significant degradation. Another recent gain comes from the elevated Cs collar temperature, which was gradually implemented to probe its impact on the performance lifetime. In addition, load resistors improve the voltage stability of the electron dump and the lenses, which now can be more finely tuned. The achieved gain allowed for lowering the RF power to ~50 kW for improved reliability. A beam current of 38 mA is required at SNS for producing neutrons with a proton beam power of 1.4 MW. In one case, after 12 days of 4% duty factor operation, 56 mA were demonstrated with 60 kW of RF power. This is close to the 59 mA required for 3 MW operations.
TRIUMF, Vancouver
LPSC, Grenoble
Most ion sources at ISOL (isotope separation on-line) facilities can produce only singly charged ions but efficient post acceleration requires high charge states. For light ions this can be achieved by stripping after a first moderate acceleration but with heavy ions this is no longer possible and charge state breeding is necessary. The breeder should be able to work at a high efficiency for the required charge state and especially for short-lived radioactive isotopes the process should be fast. For the ISAC facility at TRIUMF an ECRIS charge breeder (14 GHz PHOENIX from Pantechnik) has been chosen as it is well adapted to the continuous mode operation of the accelerator and for radioactive ions there is practically no limit for the beam intensity. After off-line optimization on a test bench the source has been moved on-line to the ISAC facility. Mass separated beams of radioactive ions from the on-line ion sources can be directed into the source. During a first test in fall 2008 a beam of 80Rb14+ was successfully created from 80Rb1+ and accelerated by the ISAC post accelerator. A summary of the results from the test bench and from the on-line commissioning will be presented.
CERN, Geneva
SLAC, Menlo Park, California
Uppsala University, Uppsala
A fundamental element of the CLIC concept is two-beam acceleration, where rf power is extracted from a high-current and low-energy beam in order to accelerate the low-current main beam to high energy. The power extraction occurs in special X-band Power Extraction and Transfer Structures (PETS). The structures are large aperture, high-group velocity and overmoded periodic structures. Following the substantial changes of the CLIC baseline parameters in 2006, the PETS design has been thoroughly updated along with the fabrication methods and corresponding rf components. Two PETS prototypes have been fabricated and high power tested. Test results and future plans are presented.
BNL, Upton, Long Island, New York
After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling was installed and commissioned with proton beam. The talk presents the status of this effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.
CERN, Geneva
With the successful circulation of beams in the Large Hadron Collider (LHC), its vacuum system becomes the World’s largest vacuum system under operation. This system is composed of 54 km of UHV vacuum for the two circulating beams and about 50 km of insulation vacuum around the cryogenic magnets and the liquid helium transfer lines. The LHC complex is completed by 7 km of high vacuum transfer lines for the injection of beams from the SPS and their dumping. Over the 54 km of UHV beam vacuum, 48 km are at cryogenic temperature (1.9 K), the remaining 6 km are at ambient temperature and use extensively non-evaporable getter (NEG) coatings, a technology that was born and industrialised at CERN. The cryogenic insulation vacuums, less demanding technically, impress by their size and volume: 50 km and 15000 m3. Once cooled at 1.9 K, the cryopumping allows reaching pressure in the 10-4 Pa range. This paper describes the LHC vacuum system, its behaviour in presence of beams as well as the detailed actions undertaken to recover its integrity after the electrical short which happened in a quadrupole bus-bar on 19th of September 2008.
GSI, Darmstadt
NSCL, East Lansing, Michigan
IAP, Frankfurt am Main
Funding: European Commission; contract number HPRI-CT-2001-50036 (HITRAP) German Ministry for Education and Research (BMBF; contract number 06 FY160I
Deceleration of heavy, highly charged ions from the ion storage ring ESR of the GSI accelerator facility with an rf-linear decelerator will provide ions up to bare uranium almost at rest for cutting edge experiments in atomic and nuclear physics. For this unique approach the beam has to be prepared well by electron cooling in the ESR to account for a 26 time increase of the transverse emittance during the following deceleration. An interdigital H-type (IH) structure and a radio-frequency quadrupole (RFQ) structure are operated in inverse to decelerate first from 4 MeV/u to 0.5 MeV/u and then to 6 keV/u. The quasi-continuous beam from the ESR is adapted, by using a double drift buncher, to match the longitudinal acceptance of the IH. Downstream from the IH-structure the 0.5 MeV/u beam is then fit with a spiral re-buncher to the RFQ, which finally decelerates the ions to 6 keV/u. First commissioning beam times have shown that the bunching works well and ions have been decelerated to 0.5 MeV/u in the IH structure. Extensive measurements of transversal emittance before and after deceleration can now be compared to beam dynamics calculations.
SLAC, Menlo Park, California
Funding: Work supported by the DOE under contract DE-AC02-76SF00515
An L-band (1.3 GHz), normal-conducting, five-cell, standing-wave cavity that was built as a prototype capture accelerator for the ILC is being high-power processed at SLAC. The goal is to demonstrate stable operation at 15 MV/m with 1 msec, 5 Hz pulses and the cavity immersed in a 0.5 T solenoidal magnetic field. This paper summarizes the performance that was ultimately achieved and describes a novel analysis of the modal content of the stored energy in the cavity after a breakdown to determine on which iris it occurred.
SLAC, Menlo Park, California
Funding: Work supported by the DOE under contract DE-AC02-76SF00515
A new facility to clean, assemble, bake and rf process TTF3-style power couplers has been completed and is in operation at SLAC. This facility includes a class-10 cleanroom, bake station and an L-band source capable of producing up to 4 MW pulses. This paper describes the facility, test results from processing pairs of couplers that will be used in cryomodules at FNAL, and efforts to simplify the design and manufacturing of the couplers for large scale use at ILC. Also, tests of the couplers to explore their power limits for use in an FNAL superconducting proton linac are presented.
TRIUMF, Vancouver
An energy upgrade in the Radioactive Ion Beam (RIB) facility at ISAC-II will see the installation of 20MV of superconducting heavy ion linac. The addition includes twenty beta=11% bulk niobium quarter wave cavities housed in three cryomodules with six cavities in the first two and eight cavities in the last. Each cavity is specified to add 1MV in accelerating potential corresponding to peak surface fields of ~30MV/m. Transverse focusing is achieved with a 9T superconducting solenoid inside each cryomodule. The first module in the expansion has now been assembled and tested. Developments include a new ball screw tuner, locally produced cavities, modified coupler design and LN2 cryogenic circuits. The new developments are described and the results of the first cold tests are presented.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Recently, an upgrade of RHIC storage RF system with a superconducting 56 MHz cavity was proposed. This upgrade will provide significant increase in the acceptance of storage RF bucket. Presently, the short bunch length for collisions is obtained via RF gymnastics with bunch rotation (called “re-bucketing”), because the length of 197MHz bucket of 5 nsec is too short to accommodate long bunches otherwise. However, some increase in the longitudinal emittance occurs during re-bucketing. The 56MHz cavity will produce sufficiently short bunches which would allow one to operate without re-bucketing procedure. This paper summarizes simulation of beam evolution due to Intra-beam scattering (IBS) for beam parameters expected with the 56 MHz SRF cavity upgrade. Expected luminosity improvement is shown both for Au ions at 100 GeV/nucleon and for protons at 250 GeV.
CERN, Geneva
Several forwards detectors have been installed in the LHC long straight sections located on each side of the experimental caverns. Most of these detectors have been designed by the LHC experiments to study the forwards physics while some of them are dedicated to the measurement of the LHC luminosity. The integration and installation of the forwards detectors have required an excellent coordination between the experiments and the different CERN groups involved into the design and installation of the LHC accelerator. In some cases the integration of these detectors has required a modification of the standard beam lines in order to maximise the physics potentiality of the detectors. Finally, additional systems have been installed in the LHC tunnel to ensure the operation of the forwards detectors in a high radiation environment.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Beam-beam effects present one of major factors limiting the luminosity of colliders. In the linac-ring option of the eRHIC design, an electron beam accelerated in a superconducting energy recovery linac collides with a proton beam circulating in the RHIC ring. Some specific features of beam-beam interactions should be carefully evaluated for the linac-ring configuration. One of the most important effects on ion beam stability originates from a strongly focused electron beam because of the beam-beam force. This electron pinch effect makes the beam-beam parameter of the ion beam several times larger than the design value, and leads to the fast emittance growth of the ion beam. The electron pinch effect can be controlled by adjustments of electron lattice and the incident emittance. We present results of simulations optimizing ion beam quality in the presence of this pinch effect.
BNL, Upton, Long Island, New York
As first step in a staged approach towards a RHIC-based electron-ion collider, installation of a 4 GeV energy-recovery linac in one of the RHIC interaction regions is currently under investigation. To minimize costs, the interaction region of this collider has to utilize the present RHIC magnets for focussing of the high-energy ion beam. Meanwhile, electron low-beta focussing needs to be added in the limited space available between the existing separator dipoles. We discuss the challenges we are facing and present the current design status of this e-A interaction region.
BNL, Upton, Long Island, New York
MIT, Middleton, Massachusetts
Funding: Work performed under US DOE contract DE-AC02-98CH1-886
Design of a medium energy electron-ion collider (MEeIC) is under development at Collider-Accelerator Department, BNL. The design envisions a construction of 4 GeV electron accelerator in a local area inside the RHIC tunnel. The electrons will be produced by a polarized electron source and accelerated in the energy recovery linac. Collisions of the electron beam with 100 GeV/u heavy ions or with 250 GeV polarized protons will be arranged in the existing IP2 interaction region of RHIC. The luminosity of electron-proton collisions at 1032 cm-2 s-1 level will be achieved with 40 mA CW electron current with presently available parameters of the proton beam. Efficient cooling of proton beam at the collision energy may bring the luminosity to 1033 cm-2 s-1 level. The important feature of the MEeIC is that it would serve as first stage of eRHIC, a future electron-ion collider at BNL with both higher luminosity and energy reach. The majority of the MEeIC accelerator components will be used for eRHIC.
JLAB, Newport News, Virginia
Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The conceptual design of a ring-ring electron-ion collider based on CEBAF has been continuously optimized to cover a wide center-of-mass energy region and to achieve high luminosity and polarization to support next generation nuclear science programs. Here, we summarize the recent design improvements and R&D progress on interaction region optics with chromatic aberration compensation, matching and tracking of electron polarization in the Figure-8 ring, beam-beam simulations and ion beam cooling studies.
KIT, Karlsruhe
CERN, Geneva
NCP, Islamabad
Fermilab, Batavia
We report about generic halo and tail simulations and estimates. Previous studies were mainly focused on very high energies as relevant for the beam delivery systems of linear colliders. We have now studied, applied and extended these simulations to lower energies as relevant for the CLIC drive beam.
Muons, Inc, Batavia
Illinois Institute of Technology, Chicago, Illinois
Funding: Work supported in part by USDOE STTR Grant DE FG02 08ER86281.
We describe an approach that can extend the utility of frictional cooling, originally developed for muon beams, to other particles and ions, producing beams of exceptionally low normalized emittance. Moreover, via this approach the small momentum acceptance typical of frictional cooling channels can be increased by two to three orders of magnitude, making it possible to handle much larger intensities with much higher transmission, while preserving the exceptionally low normalized emittance of the output. Simulation studies have been used to optimize the design and performance for a variety of ions and particles, and an inexpensive experiment has been designed to test and verify the concept and simulations, using alpha particles from a radioactive source.
ORNL, Oak Ridge, Tennessee
Funding: *SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
The combined time required for diffusion release from target materials and effusive-flow of short-lived ion species must be minimized at ISOL based radioactive ion beam (RIB) facilities. Computational simulation studies with state-of-the-art codes offer cost effective means for designing targets with optimized diffusion release properties and vapor transport systems with short path lengths, as required for such applications. To demonstrate the power of the technique for designing optimum thickness targets, analytic solutions to the diffusion equation are compared with those obtained from a finite-difference code for radioactive particle release from simple geometries. The viability of the Monte Carlo technique as a practical means for optimally designing vapor transport systems is demonstrated by simulating the effusive-flow of neutral particles through several complex vapor transport systems. Important issues which affect the yield rates of short-lived species generated in high power ISOL targets are also discussed.
CERN, Geneva
Beam losses in high-energy particle accelerators are responsible for beam lifetime degradation. In the LHC beam losses will create a shower of particles while interacting with materials from the beam pipes and surroundings, resulting in a partial activation of material in the tunnel. Efforts have been made during the accelerator design to monitor and to reduce the activation induced by beam losses. Traceability for all vacuum components has been established providing a tool to follow-up individually each component or subcomponents installed in the tunnel, regardless of their future destination e.g. recycling or disposal. In the latter case, the history of vacuum components will allow calculating the beam-induced activation and permit comparisons with in-situ and ex-situ measurements. This zoning will also help to reduce collective and individual radiation doses to personnel during interventions. The paper presents the vacuum system layout and describes the LHC vacuum zoning and its implementation using an ORACLE© database.
USTC/NSRL, Hefei, Anhui
Funding: the National Nature Science Foundation of China, Grant No. 10375060, 10375061 and 10675116
One of the major concerns in the development of hybrid dielectric-iris-loaded structure is the performance of the used dielectric. The previous dielectric is machinable but the loss tangent is slightly high. So we adopt the new dielectric (Mg-Ca-Ti-O) with loss tangent of about 2·10-4. Because of its high hardness and brittleness, the machining technology and methods are attempted. In this paper, we present a new design of the structure. The model cavities and the coupler for this structure with the new dielectric are investigated experimentally. The experiment results are accorded with the simulated results. In the end, the amplitude and phase shift of the electric field and R/Q of this structure at the operation frequency are even got by a bead-pull experiment.
IMP, Lanzhou
CSR is a new ion cooler-storage-ring system in China IMP, it consists of a main ring (CSRm) and an experimental ring (CSRe). The two existing cyclotrons of the Heavy Ion Research Facility in Lanzhou (HIRFL) are used as its injector system. The heavy ion beams from the cyclotrons are injected first into CSRm for accumulation with e-cooling and acceleration, finally extracted fast to CSRe for internal-target experiments and mass measurements of radioactive ion beams (RIBs), or extracted slowly for external-target experiments or cancer therapy. In 2005 the CSR construction was completed and the commissioning finished in the past three years. It includes stripping injection (STI), electron-cooling with hollow electron beam, C-beam stacking with the combination of STI and e-cooling, wide energy-range acceleration from 7 MeV/u to {10}00 MeV/u with the RF harmonic-number changing, multiple multi-turn injection (MMI) and beam accumulation with MMI and e-cooling for heavy-ion beams of Ar, Kr and Xe, fast and slow extraction from CSRm, the commissioning of CSRe with two lattice modes, and a RIB mass-spectrometer test with the isochronous mode in CSRe by the time-of-flight method.
BNL, Upton, Long Island, New York
For his outstanding contribution to the design and construction of accelerators that has led to the realization of major machines for fundamental science on two continents, and his promotion of international collaboration.
PPPL, Princeton, New Jersey
LLNL, Livermore, California
LBNL, Berkeley, California
Voss Scientific, Albuquerque, New Mexico
Funding: Research supported by the US Department of Energy.
Neutralized drift compression offers an effective means for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, totaling to more than a 10,000 times increase in the beam density during this process. The optimal configuration of focusing elements to mitigate the time-dependent focal plane is discussed in this paper. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present numerical modeling techniques and theoretical understanding of plasma neutralization of intense particle beams. Investigations of intense beam pulse interaction with a background plasma have identified the operating regimes for stable and neutralized propagation of intense charged particle beams.
LBNL, Berkeley, California
LLNL, Livermore, California
PPPL, Princeton, New Jersey
Voss Scientific, Albuquerque, New Mexico
The Heavy-Ion Fusion Sciences Virtual National Laboratory is pursuing an approach to target heating experiments in the warm dense matter regime, using space-charge-dominated ion beams that are simultaneously longitudinally bunched and transversely focused. Longitudinal beam compression by large factors has been demonstrated in the Neutralized Drift Compression Experiment (NDCX) with controlled ramps and forced neutralization. Using an injected 30 mA K+ ion beam with initial kinetic energy 0.3 MeV, axial compression leading to ~100X current amplification and simultaneous radial focusing to a few mm have led to encouraging energy deposition approaching the intensities required for eV-range target heating experiments. We discuss the status of several improvements to NDCX to reach the necessary higher beam intensities, including:
- greater axial compression via a longer velocity ramp;
- beam steering dipoles to mitigate aberrations in the bunching module;
- time-dependent focusing elements to correct considerable chromatic aberrations; and
- plasma injection improvements to establish a plasma density always greater than the beam density, expected to be >1013 cm-3.
HIT, Heidelberg
The Heidelberg Ion Therapy facility (HIT) is the first dedicated proton and carbon therapy facility in Europe. HIT will start treating the first patients by the end of 2008. The talk presents the commissioning experience and reports on the quality of machine operations in the clinical environment including initial treatment results. The commissioning of the Italian facility Centro Nazionale di Adroterapia Oncologica (CNAO) is also discussed.
NIRS, Chiba-shi
AEC, Chiba
Based on more than ten years of experience of the carbon cancer therapy with HIMAC, we have proposed a new treatment facility for the further development of the therapy with HIMAC. This facility will consist of three treatment rooms: two rooms equipped with horizontal and vertical beam-delivery systems and one room with a rotating gantry. For the beam-delivery system of the new treatment facility, a 3D hybrid raster-scanning method with gated irradiation with patient’s respiration has been proposed. A R&D study has been carried out toward the practical use of the proposed method, although this method was verified by a simulation study. In the R&D study, we have improved the beam control of the size, the position and the time structure for the proposed scanning method with the irradiation gated with patient’s respiration. Further, owing to the intensity upgrade of the synchrotron, we can successfully extend the flattop duration, which can complete one fractional irradiation with one operation period and can increase the treatment efficiency of the gated irradiation. We will report the recent progress on HIMAC for carbon therapy.
JAI, Oxford
Imperial College of Science and Technology, Department of Physics, London
UMAN, Manchester
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
STFC/RAL, Chilton, Didcot, Oxon
Brunel University, Middlesex
GIROB, Oxford
Fermilab, Batavia
Gray Institute for Radiation Oncology and Biology, Oxford
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Cockcroft Institute, Lancaster University, Lancaster
Funding: EPSRC EP/E032869/1
The PAMELA (Particle Accelerator for MEdicaL Applications) project is to design an accelerator for proton and light ion therapy using non-scaling Fixed Field Alternating Gradient (FFAG) accelerators, as part of the CONFORM project, which is also constructing the EMMA electron model of a non-scaling FFAG at Daresbury. This paper presents an overview of the PAMELA design, and a discussion of the design goals and the principles used to arrive at a preliminary specification of the accelerator.
KURRI, Osaka
University of Fukui, Faculty of Engineering, Fukui
Accelerator based neutron source with an internal target (ERIT-emittance recovery internal target) placed into the proton storage ring has been developed. In this scheme, the beam and energy degradation caused by the target are cured by ionization cooling and the thermal and epi-thermal neutron flux of more than 1x109 n/cm2/sec can be obtained. The experimental results will be given in the conference.
CERN, Geneva
SLAC, Menlo Park, California
The LHC collimation system is implemented in phases, in view of the required extrapolation by 2-3 orders of magnitude beyond Tevatron and HERA experience in stored energy. All available simulations predict that the LHC proton beam intensity with the "phase 1" collimation system may be limited by the impedance of the collimators or cleaning efficiency. Maximum efficiency requires collimator materials very close to the beam, generating the dominant resistive impedance in the LHC. Above a certain intensity the beam is unstable. On the other hand, even if collimators are set very close to the beam, the achievable cleaning efficiency is predicted to be inadequate, requiring either beam stability beyond specifications or reduced intensity. The accelerator physics concept for upgrading cleaning efficiency, for both proton and heavy ion beams, and reducing collimator-related impedance is described. Besides the "phase 2" secondary collimators, new collimators are required in a few super-conducting regions.
GSI, Darmstadt
The conservation of the longitudinal beam quality through the SIS-18/100 synchrotron chain is of major importance for the FAIR accelerator project as well as for the SIS-18 upgrade. The generation of a short, intense heavy ion bunch at the end of the machine cycle defines a tight budget for the tolerable longitudinal emittance growth. Potential sources of bunch quality degradation are intensity effects and non-adiabatic rf ramps during the rf capture in SIS-18 and during the barrier bucket pre-compression in SIS-100. The time spend on rf manipulations has to be as small as possible in order to maximize the repetition rate. We report about theoretical and experimental studies in SIS-18 of optimized voltage ramps for rf capture into single and double rf buckets, including space charge and beam-loading effects. Further we show that longitudinal space charge can improve the efficiency of rf manipulations. As an example we present an optimized barrier bucket pre-compression scheme for SIS-100.
Kyoto ICR, Uji, Kyoto
MPI-K, Heidelberg
Kyoto IAE, Kyoto
HU/AdSM, Higashi-Hiroshima
AEC, Chiba
NIRS, Chiba-shi
JINR, Dubna, Moscow Region
Funding: This work is supported by Advanced Accelerator Development Project of MEXT and the Global COE program "The Next Generation of Physics, Spun from Universality and Emergence".
Transverse laser cooling experiments of 24Mg+ beam have been carried out at S-LSR, which is a small ion storage and cooler ring. According to a simulation, it is expected that under such a condition as the difference of synchrotron and betatron tunes is near integer, synchro-betatron coupling occurs and transverse laser cooling will be achieved*. In order to confirm this situation, the horizontal beam size and momentum spread are measured optically with CCD camera and PAT (post acceleration tube), respectively**,***. CCD camera observes fluorescence from the beam at the laser cooling section. Typical measured horizontal beam size is 0.5mm (1 σ). In some condition, an increase of fluorescence strength is observed, which indicates the beam concentration to the center, where the beam and the laser can interact. PAT is utilized for measurement of a longitudinal beam velocity profile. By application of electric potential to the PAT, the beam velocity is slightly modified. Since only particles which have velocities in a certain region can interact with the laser, the time variation of the florescence during voltage sweep represents the longitudinal velocity profile of the beam.
*H. Okamoto, Phys. Rev. E 50, 4982 (1994)
**B. Wanner et al., Phys. Rev. A 58, 2242 (1998)
***T. Ishikawa, Master's thesis, Kyoto University (2008)
Kyoto ICR, Uji, Kyoto
MPI-K, Heidelberg
Kyoto IAE, Kyoto
JINR, Dubna, Moscow Region
NIRS, Chiba-shi
HU/AdSM, Higashi-Hiroshima
AEC, Chiba
Funding: The present work was supported by Advanced Compact Accelerator Development program by MEXT of Japanese Government. Support from Global COE, The Next Generation of Physics, is also greatly appreciated.
Creation of 3-dimensional crystalline beam by application of laser-cooling for a Mg ion beam with kinetic energy of 40 keV is a major research subject of the ion storage ring, S-LSR, at ICR, Kyoto University*. Based on the success of longitudinal laser cooling in 2007**, an approach to extend the effect of laser cooling to the transverse degree of freedom has been performed. An indication of heat transfer from the horizontal to longitudinal direction has been obtained by synchro-betatron coupling. By application of bunched beam laser cooling at the operation point around (2.07, 1.10), the momentum spread of the cooled ion beam has been observed to have a peak at a synchrotron tune around 0.07 and simultaneously transverse beam size seems to be reduced in this region. An increase of beam brightness in the horizontal profile has also been observed by measuring spontaneous emission of absorbed laser light. In the present paper, strategy to reach the final 3-dimensional crystalline state by application of 3-dimensional laser cooling by careful adjustment of coupling among 3 degrees of freedom is to be presented based upon the recent experimental results.
*A. Noda, M. Ikegami, T. Shirai, New Journal of Physics, 8, 288-307(2006).
**M. Tanabe et al.,Applied Physics Express 1, 028001-1-028001-3 (2008).
Far-Tech, Inc., San Diego, California
Funding: DOE
IonEx is a new hybrid, meshless, cross-platform, 2D code which can model the extraction of ions from a plasma device. The application includes a user-friendly Graphical User Interface (GUI), which contains a geometry editor for specifying the domain. The design of IonEx utilizes the object-oriented functionality of C++, which provides an efficient means of incorporating a magnetic field, an arbitrary geometry, and an unlimited number of ion species into a simulation. Visualization of the resulting trajectories and emittances is accomplished through the GUI; openGL is used to accelerate the graphics. In this paper we will briefly review the physics and computational methods used, highlight important aspects of the object-oriented design, discuss the primary features of the GUI, describe the current status of IonEx, and present some simulation results.
Far-Tech, Inc., San Diego, California
ANL, Argonne
Funding: This work is supported by the US DOE SBIR program
GEM, developed by FAR-TECH Inc, is a self consistent hybrid code to simulate general ECRIS plasma. It calculates EDF (electron distribution function) using a bounce-averaged Fokker-Planck code and calculates the ion flow using a fluid code, which has been modified to implement new boundary settings including fixed boundary ion velocities or fixed sheath potentials at both ends of the device. Extensive studies on the convergence and performance of the code have been performed. Also, GEM has been connected to MCBC (Monte Carlo beam capture) code and the validations of the code using ANL ECR-I charge breeding data and other published experiments are underway. The typical converged solutions of GEM and the comparisons with the experiments will be presented and discussed.
LLNL, Livermore, California
LBNL, Berkeley, California
Funding: Work performed under the auspices of US Department of Energy by LLNL under Contract DE- AC52-07NA27344 and by LBNL under Contract DE-AC03-76SF00098.
The Virtual National Laboratory for Heavy-Ion Fusion is developing a physics design for NDCX-II, an experiment to study warm dense matter heated by ions near the Bragg-peak energy. Present plans call for using about thirty induction cells to accelerate 30 nC of Li+ ions to more than 3 MeV, followed by neutralized drift-compression. To heat targets to useful temperatures, the beam must be compressed to a sub-millimeter radius and a duration of about 1 ns. An interactive 1-D particle-in-cell simulation with an electrostatic field solver, acceleation-gap fringe fields, and a library of realizable analytic waveforms has been used for developing NDCX-II acceleration schedules. Multidimensional source-to-final-focus simulations with the particle-in-cell code Warp have validated this 1-D model and have been used both to design transverse focusing and to compensate for injection non-uniformities and 3-D effects. Results from this work are presented, and ongoing work to replace the analytic waveforms with output from circuit models is discussed.
MPI-P, München
CANDLE, Yerevan
YSU, Yerevan
DESY, Hamburg
At DESY the PETRA accelerator has been converted into a new 3rd generation high-brilliance synchrotron radiation facility called PETRA III. For the first commissioning in spring 2009 a positron beam is used. In the future it is also foreseen to operate the synchrotron light source with an electron beam. Ion effects pose a potential problem to the electron beam operation of PETRA III. In this paper, a weak-strong simulation code is employed to study the ion effect issues in detail for different operation scenarios.
BNL, Upton, Long Island, New York
A gas fluorescence beam profile monitor has been realized at the relativistic heavy ion collider (RHIC) using the polarized atomic hydrogen gas jet. RHIC proton beam profiles in the vertical plane are obtained as well as measurements of the width of the gas jet in the beam direction. For gold ion beams, the fluorescence cross section is sufficiently large so that profiles can be obtained from the residual gas alone, albeit with long light integration times and lower number of Au ions than protons. We estimate the fluorescence cross-section of 100 GeV protons and Au ions on hydrogen gas to be 6.6x10-21 cm2 ~1.7x10-16 cm2, respectively*. We calculate the beam emittance to provide an independent measurement of the RHIC beam. This optical beam diagnostic technique, utilizing the beam induced fluorescence from injected or residual gas, represents a step towards the realization of a simple and truly noninvasive beam monitor for high-energy particle beams together with a wall-current-monitor system and/or a low light level optical temporal measurement system, a 3-dimensional particle beam profile system can be envisioned providing routine diagnosis of high-energy particle beams.
*T. Tsang, et. al., Rev. Sci. Instrum. 79, 105103 (2008).
IHEP Beijing, Beijing
A set of IPM system will be built on RCS of CSNS to measure vertical and horizontal beam profiles. Detailed conceptual design of an IPM system for CSNS is described in this paper. Wire electrodes are introduced to get a more uniform electric field, and a ‘C’ type electromagnet is designed to exert a uniform magnetic field to the ionization area. The magnetic field is parallel with the sweeping electric field and will inhibit the defocusing effects of space charge and recoil momentum.
Imperial College of Science and Technology, Department of Physics, London
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
The RAL Front End Test Stand is being constructed to demonstrate production of a high-quality, chopped 60 mA H- beam at 3 MeV and 50 pps. In parallel to the accelerator development, non-destructive laser-based beam diagnostics are being designed. This paper reports on the realisation of a laser-based profile instrument that will be able to reconstruct the complete 2D transverse beam density distribution by scanning a laser beam through the ion beam at a variety of angles and then computationally combining the results. Commissioning results are presented alongside plans for future developments.
Muons, Inc, Batavia
Enrico Fermi Institute, University of Chicago, Chicago, Illinois
Many measurements in particle and accelerator physics are limited by the time resolution with which individual particles can be detected. This includes particle identification via time-of-flight in major experiments like CDF at Fermilab and Atlas and CMS at the LHC, as well as the measurement of longitudinal variables in accelerator physics experiments. Large-scale systems, such as neutrino detectors, could be significantly improved by inexpensive, large-area photo detectors with resolutions of a few millimeters in space and a few picoseconds in time. Recent innovations make inexpensive, large-area detectors possible, with only minor compromises in spatial and time resolution. The G4beamline program [1] is one of the appropriate tools for simulation of low-energy physics processes. The set of specialized tools - MCPS [2], POISSON-2 [3] and Monte Carlo Simulator was used for numerical study of different photo multipliers.
ANL, Argonne
Funding: This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
A Cf-252 fission source yields neutron-rich fission fragments. The CAlifornium Rare Ion Breeder Upgrade (CARIBU) project is an upgrade to the Argonne Tandem Linear Accelerator System (ATLAS) that provides a 37 GBq (1 Ci) source of these radioactive ions for acceleration. Fission fragments stop in a gas catcher, are extracted into an ECR ion source to increase the charge state, and then accelerated in ATLAS. The radiation fields produced by an unshielded 1 Ci 252Cf source are 46 rem/hr (neutron) and 4 R/hr (gamma) at 30 cm. A shielding system has been constructed that reduces the radiation fields to ≤ 1 mrem/hr at 30 cm from all accessible surfaces. The MCNPX code was used to model the transport of the spontaneous fission neutrons and gamma radiation, and the gamma radiation induced in the shielding materials by the neutrons. The primary neutron shielding material chosen was 5% borated polyethylene, enclosed in steel. Calculations are made for emissions of radioactive effluents, primarily noble gases, using the EPA CAP-88 computer program. The maximum credible incident scenario releases a small quantity of Cf-252. Calculated dose results and mitigation methods are presented.
JAEA/J-PARC, Tokai-mura
KEK, Ibaraki
JAEA/LINAC, Ibaraki-ken
JAEA, Ibaraki-ken
Over hundred beam loss monitors (BLM) in the J-PARC LINAC have been used to measure the beam loss observed during the accelerator operation. Dose rates distributed in LINAC area were compared with beam loss records taken by the BLMs. This paper describes the results of the operational data and their comparisons with the dose rates of LINAC area.
UMAN, Manchester
CERN, Geneva
The upgrade of the normal conducting REX-ISOLDE heavy ion accelerator at CERN, under the HIE-ISOLDE framework, proposes the use of superconducting (SC) quarter-wave resonators (QWRs) to increase the energy capability of the facility from 3 MeV/u to beyond 10 MeV/u. A beam dynamics study of a lattice design comprising SC QWRs and SC solenoids has confirmed the design's ability to accelerate ions, with a mass-to-charge ratio in the range 2.5 < A/q < 4.5, to the target energy with a minimal emittance increase. We report on the development of this study to include the implementation of realistic fields within the QWRs and solenoids. A preliminary error study is presented in order to constrain tolerances on the manufacturing and alignment of the linac.
CERN, Geneva
Control of beam losses is an important aspect of the H- injection system for the PS2, a proposed replacement of the CPS in the CERN injector complex. H- ions may pass the foil unstripped or be partially stripped to excited H0 states which may be stripped in the subsequent strong-field chicane magnet. Depending on the choice of the magnetic field, atoms in the ground and first excited states can be extracted and dumped. The conceptual design of the waste beam handling is presented, including local collimation and the dump line, both of which must take into account the divergence of the beam from stripping in fringe fields. Beam load estimates and activation related requirements of the local collimators and dump are briefly discussed.
NSCL, East Lansing, Michigan
LBNL, Berkeley, California
Funding: U.S. Department of Energy
A driver linac has been designed for the proposed Facility for Rare Isotope Beam (FRIB) at Michigan State University. FRIB is a lower cost and reduced scope alternative to the Rare Isotope Accelerator (RIA) project. The superconducting driver linac will accelerate stable isotope beams to energies ≥200 MeV/u with a beam power up to 400 kW for the production of rare isotope beams. The driver linac consists of a front-end and two segments of superconducting linac connected by a charge stripping station. End-to-end beam simulation studies with high statistics have been performed using the RIAPMTQ and IMPACT codes on high performance parallel computers. These studies include misalignment of beam elements, rf amplitude and phase errors for cavities, and thickness variation of the stripping foil. Three-dimensional fields of the superconducting solenoids and cavities were used in the lattice evaluation. The simulation results demonstrate good driver linac performance. No uncontrolled beam losses were observed even for the challenging case of multiple charge state uranium beam acceleration. The beam dynamics issues will be discussed and the detail beam simulation results presented.
ORNL, Oak Ridge, Tennessee
Funding: *SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The new SNS Allison emittance scanner measures emittances of 65 kV ion beams over a range of ± 116 mrad. Its versatile control system allows for time-dependent emittance measurements synchronized by an external trigger, and therefore is suited for studying pulsed systems. After a programmable delay the system acquires a variable array of beam current measurements, each averaged over a changeable time span. The baseline of the current measurements are determined by averaging a fraction of 1 ms shortly before the start of the ion beam pulse. This paper presents the time evolution of emittance ellipses during the 1 ms H- beam pulses emerging from the SNS test LEBT, which is important for loss considerations. In addition it presents the time evolution of emittance ellipses during the 3 week active lifetime of an SNS H- source, which is an operational issue. Additional emittance data characterize the dependence on the electron-dump voltage, the extractor voltage, and the LEBT lens voltages, all of which were critical for reaching the 38 mA baseline H- beam current. Emittance data for the dependence on the beam current highlight the challenges for the SNS power upgrade.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
MPI-K, Heidelberg
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH.
The novel electrostatic Ultra-low energy Storage Ring (USR), planned to be installed at the future Facility for Low-energy Antiproton and Ion Research (FLAIR), will slow down antiprotons and possibly highly charged ions down to 20 keV/q. This multipurpose machine puts challenging demands on the necessary beam instrumentation. Ultra-short bunches (1-2 ns) on the one hand and a quasi-DC beam structure on the other, together with a variable very low beam energies (20-300 keV/q), ultra-low currents (down to 1 nA or even less for a non-circulating beam) and few particles (< 2x107), require the development of new diagnostic devices as most of the standard techniques are not suitable. Several solutions, like resonant capacitive pick-ups, beam profile monitors, Faraday cups or cryogenic current comparators, are under consideration. This contribution presents the beam instrumentation foreseen for the USR.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
Funding: Supported by the EU under contract PITN-GA-2008-215080
Beam diagnostics is a rich field in which a great variety of physical effects are made use of and consequently provides a wide and solid base for the training of young researchers. Moreover, the principles that are used in any beam monitor or detector enter readily into industrial applications or the medical sector which guarantees that training of young researchers in this field is of relevance far beyond the pure field of particle accelerators. DITANET- "DIagnostic Techniques for particle Accelerators a European NETwork" - covers the development of advanced beam diagnostic methods for a wide range of existing or future accelerators, both for electrons and ions. DITANET is the largest ever coordinated EU education action for PhD students in the field of beam diagnostic techniques for future particle accelerators with a total budget of 4.2 M. This contribution gives an overview of the network’s activities and outlines selected research results from the consortium.
JLAB, Newport News, Virginia
RUBYTRON, Rye Brook, New York
In-air test fixtures for beamline elements typically utilize an X-Y positioning stage, and a wire antenna excited by an RF source. In most cases, the antenna contains a standing wave, and is useful only for coarse alignment measurements in CW mode. A surface-wave (SW) based transmission line permits RF energy to be launched on the wire, travel through the beamline component, and then be absorbed in a load. Since SW transmission lines employ traveling waves, the RF energy can be made to resemble the electron beam, limited only by ohmic losses and dispersion. Although lossy coaxial systems are also a consideration, the diameter of the coax introduces large uncertainties in centroid location. A SW wire is easily constructed out of 200 micron magnet wire, which more accurately approximates the physical profile of the electron beam. Benefits of this test fixture include accurate field mapping, absolute calibration for given beam currents, Z-axis independence, and temporal response measurements of sub-nanosecond pulse structures. Descriptions of the surface wave launching technique, transmission line, and receiver electronics are presented, along with measurement data.
BNL, Upton, Long Island, New York
The talk reviews the RHIC performance, including the unprecedented manipulations of polarized beams and the recent low energy operations. Achievements and limiting factors of RHIC operation are discussed, e.g. intrabeam scattering, electron cloud, beam-beam effects, magnet vibrations, and the efficiency of novel countermeasures such as bunched beam stochastic cooling, beam conditioning and chamber coatings. The future upgrade plans and the pertinent R&D program will also be presented.
MIT, Middleton, Massachusetts
There are presently three initiatives for a hadron-lepton collider in the world: eRHIC at BNL, ELIC at JLab (both part of the EIC collaboration), and LHeC at CERN. This talk presents the status of these initiatives and compares their different thrusts in physics research as well as in their approach to the facility design, pointing out the strengths and limits of each particular proposal.
GSI, Darmstadt
CERN, Geneva
The FAIR storage ring complex comprises three storage rings with a magnetic rigidity of 13 m. Each of the rings, CR, RESR, and NESR, serves specific tasks in the preparation of secondary beams, rare isotopes and antiprotons, or for experiments with heavy ion beams. The CR is optimized for fast stochastic pre-cooling of secondary beams. The RESR design includes optimization of antiproton accumulation. The design of the NESR for experiments with heavy ions, deceleration of ions or antiprotons for a subsequent low energy facility, and the accumulation of rare isotope beams is proceeding. This report summarizes various new concepts conceived in the design process of this new storage ring facility.
GANIL, Caen
The SPIRAL 2 superconducting linac is currently under construction. This talk describes the collaboration effort with industrial partners to fabricate the two cryomodule families: the low beta Cryomodule A, and the high beta Cryomodule B. The low beta family is composed of 12 single cavity cryomodules. The high energy section is composed of 7 cryomodules hosting 2 cavities each. The design goal for the accelerating field Eacc of the SPIRAL 2 QWRs is 6.5 MV/m.
NSCL, East Lansing, Michigan
Funding: This work was supported by Michigan State University and the National Science Foundation under grant PHY-0110253.
The NSCL at Michigan State University (MSU) is implementing a system called the ReA3 to reaccelerate rare isotope beams from projectile fragmentation to energies of about 3 MeV/u. The re-acceleration system uses an Electron Beam Ion Trap (EBIT) to provide a compact and cost efficient system. We discuss the design parameters for a m/q separator that is to be used to separate highly charged ions from an EBIT type charge breeder. The separator is designed to accept ions at 12 keV/u with mass to charge ratios in the range of m/q = 2.5 to 5 amu. The goal is to separate selected rare isotope species from any residual ions before injecting them into the ReA3 linear accelerator system. Using ray tracing simulations with SIMION*, as well as higher order map calculations with COSY INFINITY**, the performance of the separator has been evaluated in terms of the expected mass resolution and overall acceptance. The separator consists of a magnetic sector and a series of electrostatic devices to obtain a first order achromatic tune. For comparison, similar performance values will be derived as those for a similar separator constructed at REX-ISOLDE***.
*D.A. Dahl, Int. J. Mass Spectrom. Ion Processes 200, 3 (2000) .
**K. Makino and M. Berz, Nucl. Instr. and Meth. A 558, 346 (2005)
***R. Rao et. al., EPAC-98, Stockholm, Sweden, 2132-2134 (1998).
Fermilab, Batavia
PPPL, Princeton, New Jersey
Funding: Research supported by the U.S. Department of Energy.
Understanding the effects of random errors in machine components such as quadrupole magnets and RF cavities is essential for the optimum design and stable operation of high-intensity accelerators. The effects of random errors have been studied theoretically, but systematic experimental studies have been somewhat limited due to the lack of dedicated experimental facilities. In this paper, based on the compelling physics analogy between intense beam propagation through a periodic focusing quadrupole magnet system and pure ion plasma confined in a linear Paul trap, experimental studies of random error effects have been performed using the Paul Trap Simulator Experiment (PTSX). It is shown that random errors in the quadrupole focusing strength continuously produce a non-thermal tail of trapped ions, and increases the rms radius and the transverse emittance almost linearly with the amplitude and duration of the noise. This result is consistent with 2D WARP PIC simulations. In particular, it is observed that random error effect can be further enhanced in the presence of beam mismatch.
Tech-X, Boulder, Colorado
BNL, Upton, Long Island, New York
Funding: Supported by the US DOE Office of Nuclear Physics under grants DE-FC02-07ER41499 and DE-FG02-04ER84094; used NERSC resources under grant DE-AC02-05CH11231.
Magnetic field errors can limit the dynamical friction force on co-propagating ions and, hence, increase the cooling time. We present theoretical and numerical results for reduction of the friction force due to bounded transverse magnetic field errors, as a function of wavelength. VORPAL * simulations using a binary collision algorithm ** show that small-wavelength field errors affect the friction logarithmically, via the Coulomb log, while long-wavelength errors reduce the friction by effectively increasing the transverse electron temperature. A complete understanding of finite-time effects and the role of small impact parameter collisions is required to correctly interpret the simulation results. We show that the distribution of electron-ion impact parameters is similar to a Pareto distribution, for which the central limit theorem does not apply. A new code has been developed to calculate the cumulative distribution function of electron-ion impact parameters and thus correctly estimate the expectation value and uncertainty of the friction force.
* C. Nieter and J. Cary, J. Comp. Phys. 196 (2004), p. 448.
** G. Bell et al., J. Comp. Phys. 227 (2008), p. 8714.
TUE, Eindhoven
Pulsar Physics, Eindhoven
The General Particle Tracer (GPT) code is a well established package for the design of charged particle accelerators and beam lines. A crucial component of this code is the calculation of Coulomb interactions. In this contribution we present two different numerical algorithms for the calculation of these particle-particle effects: The standard Particle-In-Cell (PIC) method and a Barnes-Hut (B&H) treecode approach. The PIC method is fast and reliable, but it does not include binary interactions. The method is therefore inapplicable when disorder induced heating plays a role, for example in electron microscopes and focused ion beams. The Barnes-Hut method, borrowed from the astrophysics community, calculates all pair wise interactions in an efficient manner. This approach covers all Coulomb effects, but it is potentially much slower. A realistic test case is presented highlighting the strengths and weaknesses of both approaches.
SLAC, Menlo Park, California
UCLA, Los Angeles, California
The effect of ion motion and the need for practical positron propagation in a plasma wakefield accelerator (PWFA) have incited interest in hollow plasma channels. These channels are typically assumed to be cylindrically symmetric; however, a different geometry might be easier to achieve. The introduction of an obstruction into the outlet of a high Mach number gas jet can produce two parallel slabs of gas separated by a density depression. Here, there is a detailed simulation study of the density depression created in such a system. This investigation reveals that the density depression is insufficient at the desired plasma density. However, insights from the simulations suggest another avenue for the creation of the hollow slab geometry.
USC, Los Angeles, California
UCLA, Los Angeles, California
Duke University, Durham, North Carolina
Funding: Work supported by US Department of Energy.
Plasma Wakefield Accelerator has been proven to be a promising technique to lower the cost of the future high energy colliders by offering orders of magnitude higher gradients than the conventional accelerators. However, it has been shown that ion motion is an important issue to account for in the extreme regime of ultra high intensities and ultra low emittances, characteristics of future high energy colliders. In this regime, the transverse electric field of the beam is so high that the plasma ions cannot be considered immobile at the time scale of electron plasma oscillations, thereby leading to a nonlinear focusing force. Therefore, the transverse emittance of a beam matched to the initial linear focusing will not be preserved under these circumstances. However, Vlasov equation predicts a matching profile even in the nonlinear regime. Furthermore, we extend the idea and introduce a plasma section that can match the entire beam to the mobile-ion regime of plasma. We also find the analytic solution for the optimal matching section. Simulation results will be presented.
CERN, Geneva
The specification for vacuum pressure in the CLIC electron Main Linac critically depends on the fast ion instability. In fact, the maximum tolerable pressure value in the pipe of the Main Linac is dictated by the threshold above which the fast ion instability sets in over a CLIC bunch train. Previous calculation based on ion generation from residual gas ionization alone showed that, due to the loss of the trapping along the linac caused by the beam size shrinking from acceleration, a pressure as high as 10 nTorr could be accepted, higher than the tolerable value in the long transfer line. However, since the accelerated beam becomes transversely very small, its electric field can reach values above the field ionization threshold. When this happens, the whole space region with a sufficiently high electric field gets instantly fully ionized by the first bunch and the effect on the bunch train could be severe. We have modeled field ionization in our simulation code FASTION and re-evaluated the onset of fast ion instability in the Main Linac.
PPPL, Princeton, New Jersey
Funding: Research supported by the U.S. Department of Energy.
The Paul Trap Simulator Experiment (PTSX) is a compact laboratory Paul trap that simulates a long, thin charged-particle bunch coasting through a kilometers-long magnetic alternating-gradient (AG) transport system by putting the physicist in the frame-of-reference of the beam. Results are presented from experiments in which the axial distribution function is modified by lowering the axial confinement barrier to allow particles in the tail of the axial distribution function to escape. Measurements of the axial energy distribution and the transverse density profile are taken to determine the effects of the modified distribution function on the charge bunch. It is observed that the reduced axial-trapping potential leads to an increase of the transverse effective temperature.
SLAC, Menlo Park, California
A proposed high-brightness synchrotron light source (PEP-X) is under design at SLAC. The 4.5-GeV PEP-X storage ring has four theoretical minimum emittance (TME) cells to achieve the very low emittance and two double-bend achromat (DBA) cells to provide spaces for IDs. Damping wigglers will be installed in zero-dispersion straights to reduce the emittance below 0.1 nm. Ion induced beam instability is one critical issue due to its ultra small emittance. Third harmonic cavity can be used to lengthen the bunch in order to improve the beam life time. Bunch-train filling pattern is proposed to mitigate both the fast ion instability and beam loading effect. This paper investigates the fast ion instability and beam loading for different beam filling patterns.
UW-Madison/SRC, Madison, Wisconsin
An electron beam focused by an ion channel without a magnetic field, in the so-called ion focus regime (IFR), may be disrupted by the transverse ion hose instability. We describe the growth in four regimes.
GSI, Darmstadt
Cosylab, Ljubljana
One of the main challenges of the planned Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is to handle its complex parallel and multiplexed beam operation. In addition, the size of the FAIR project demands for tailor-made but yet extendible solutions with respect to all technical subsystems, especially for the control system. In order to operate and maintain the large amount of front-end equipment standardized solutions are an absolute must. Moreover, to give guidelines and interface specifications to the international collaborators and external partners for so-called "in-kind contributions" facility-wide standards have to be defined. For that purpose, GSI decided to use the Front-end Software Architecture (FESA) at the lowest level of the control system. FESA was developed by CERN and is already operational at LHC and its injectors. This report presents a framework overview and summarizes the status of the FESA test installation at GSI. Additionally, first experiences with the SIS18 BPM system controlled via FESA are presented.
IST, Lisboa
ISEL, Lisboa
The Ion Beam Laboratory of the Technological Nuclear Institute (ITN) in Lisbon has a particle accelerator based on the Van de Graaff machine which is used for research in the area of material characterization. The Van de Graaff particle accelerator* in the ITN is an horizontal electrostatic accelerator capable of producing Helium and Hydrogen ion beams with energies up to 3 MeV. The developed system comprises the accelerator turn-on and turn-off procedures during a normal run, which includes the set of terminal voltage, ion source, beam focusing and control of ion beam current and energy during operation. In addition, the computer monitors the vacuum and is able to make a detail register of the most important events during a normal run, allowing the use of the machine by less qualified technicians in safe conditions. The data acquisition system consists in PC, a data acquisition I/O board compose by with two multifunction input/output boards from National Instruments and five electronic modules. The computer control system uses a LabVIEW synoptic for interaction with the operator and an I/O board that interfaces the computer and the accelerator system.
*Rosenblatt, J. “Particle Acceleration”. London, Methuen and Co LTD., 1968.
MPI-K, Heidelberg
Weizmann Institute of Science, Physics, Rehovot
Funding: This work is supported by the Max Planck Society.
An electrostatic Cryogenic Storage Ring (CSR) is currently being built in Heidelberg, Germany. The current status and final design of this ring, with a focus on the precision chamber suspension, optimized 2K chamber cooling, and the cryogenic pumping down to extremely low pressures will be presented. This ring will allow long storage times of ion beams with energies in the range of keV per charge for highly charged ions and polyatomic molecules. Combined with vacuum chamber temperatures approaching 2K, infrared-active molecular ions will be radiatively cooled to their rotational ground states. Many aspects of this concept were experimentally tested with a cryogenic trap for fast ion beams (CTF), which has already demonstrated the storage of fast ion beams in a large cryogenic device. An upcoming test will investigate the effect of pre-baking the cryogenic vacuum chambers to 600K on the cryogenic vacuum and the ion beam storage.
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH.
One of the central goals of the Ultra-Low energy Storage Ring (USR) project within the future Facility for Low-energy Antiproton and Ion Research (FLAIR) is to provide very short bunches in the 1-2 nanosecond regime to pave the way for kinematically complete measurements of the collision dynamics of fundamental few-body quantum systems for the first time on the level of differential cross sections. The “short pulse” operation mode may be split up in two steps: First, the cooled coasting beam of low energy ions will be adiabatically captured by a high harmonic RF cavity (20 MHz) into ~50 ns buckets. Second, the beam will be compressed to very short pulses with a desired width of only 1-2 ns by an RF buncher located 2 m in front of the so-called reaction microscope. To efficiently limit the beam energy spread, RF decompression is then done at after the experiment to avoid beam losses. In this contribution, we present numerical investigations of this very particular operation mode.
KUK, Abha
KACST, Riyadh
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
A state-of-the-art fixed energy electrostatic storage ring that will allow for precision experiments with most different kinds of ions in the energy range of up to 30 keV will be constructed and operated at the National Center for Mathematic and Physics (NCMP) at the King Abdulaziz City for Science and Technology (KACST). The ring is planed to be the central machine of a unique and highly flexible experimental platform. The lattice design therefore has to cover the different experimental techniques that the ring will be equipped with, such as e.g. electron-ion crossed-beams and ion-laser/ion-ion/ion-neutral merged-beams techniques. This paper presents the technical and particle optical design of this novel machine, explains the particular challenges in its layout, and reports on the general project status.
BNL, Upton, Long Island, New York
Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
IAP, Frankfurt am Main
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A new 4 rod RFQ fabricated by IAP, Frankfurt, is being commissioned at Brookhaven National Laboratory. The RFQ will accelerate intense heavy ion beams provided by an Electron Beam Ion Source (EBIS) up to 300 keV/u. The RFQ will accelerate a range of Q/M from 1 to 1/6, and the accelerated beam will be finally delivered to RHIC and NSRL. The first beam test is planned to use beams from the BNL Test EBIS. The detailed test results will be presented.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The present FNAL Linac H- injector has been operational since 1978 and consists of a magnetron H- source and a 750-keV Cockcroft-Walton Accelerator. The proposed upgrade to this injector is to replace the present magnetron source having a rectangular aperture with a circular aperture, and to replace the Cockcroft-Walton with a 200-MHz RFQ. Operational experience at other laboratories has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.
GSI, Darmstadt
The GSI UNILAC serving as a high duty factor heavy ion linac is in operation since nearly 35 years. An upgrade program dedicated to FAIR will be finished until 2011. For the FAIR project the synchrotron SIS 18 has to be filled up to the space charge limit. After re-commissioning of the UNILAC the replacement of the main DTL is foreseen. A new 4 MV/m 108 MHz IH-LINAC provides a high intensity 5 MeV/u U4+-beam. The existing gas stripper section is reused to perform a beam intensity of 24 emA in charge state 42+. The existing UNLAC-tunnel may house a high efficient linac structure. A superconducting or normal conducting 324 MHz-CH-linac (crossbar H-structure) is under consideration as well as rf-resonators of half wave or quarter wave type. The new high energy linac should be able to boost the beam energy up to 30 MeV/u. A further upgrade option is a second 100 m-linac (324 MHz) to enhance the beam energy to up to 100 MeV/u (U41+), sufficient to feed the FAIR 100 Tm synchrotron in direct line. The paper will report on the ongoing conceptual layout of a new UNILAC-concept.
IAP, Frankfurt am Main
The superconducting CH-cavity is the first multi-cell drift tube cavity for the low and medium energy range of proton and ion linacs. A 19 cell, beta=0.1 cavity has been developed and tested successfully with gradients of up to 7 MV/m. A piezo based fast tuner system has been developped. First horizontal tests of the cavity in a cryo-module with tuner are presented. Additionally, the construction of a new superconducting 325 MHz 7-gap CH-cavity has started. This cavity has an optimized geometry with respect to tuning possibilities, high power RF coupling and minimized end cell lengths. After low power tests it is planned to test this cavity with a 11.4 MeV/u beam delivered by the Unilac at GSI.
IAP, Frankfurt am Main
The goal of the Frankfurt Funneling Experiment is to multiply beam currents by merging two low energy ion beams. In an ideal case this would be done without any emittance growth. Our setup consists of two ion sources, a Two-Beam-RFQ accelerator and a multi cell deflector which bends the beams to one common beam axis. Current work is the design of a new beam transport system between RFQ accelerator and deflector. With extended RFQ-electrodes the drift between the Two-Beam-RFQ and the rf-deflector will be minimized and therefor unwanted emittance growth prohibited. First rf measurements with a scaled experiment will be presented.
IAP, Frankfurt am Main
Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with a electrostatic lens systems, a Two-Beam RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ and the last parts of the RFQ electrodes achieve a 3d focus at the crossing point of the two beam axis. A funneling deflector combines the bunches to a common beam axis. The optimized ion sources are adapted to the front end bunching section. Recent funneling measurements with the one-gap and the multi-gap deflector will be presented.
IAP, Frankfurt am Main
GSI, Darmstadt
A new CW-RFQ will be built for the upgrade of the HLI (High Charge State Injector) of GSI for operating with a 28 GHz-ECR-Ion source and simultaneous increase of the beam duty cycle from 25% to 100 %. The new HLI 4-rod RFQ will accelerate charged ions from 4 keV/u to 300 keV/u for the injection into the IH-structure The design had been optimized to get a rather short structure with LRFQ=2m to match the available RF-power of max. 60 kW in cw. High beam transmission, a small energy spread and small transverse emittance growth and good input matching were design goals. Properties of this CW-RFQ and status of project will be presented.
Imperial College of Science and Technology, Department of Physics, London
The PAMELA project aims to design an ns-FFAG accelerator for cancer therapy using protons and carbon ions. For the injection system for carbon ions, an RFQ is one option for the first stage of acceleration. An integrated RFQ design process has been developed using various software packages to take the design parameters for the RFQ, convert this automatically to a CAD model using Autodesk Inventor, and calculate the electric field map for the CAD model using CST EM STUDIO. Particles can then be tracked through this field map using Pulsar Physics’ General Particle Tracer (GPT). Our software uses Visual Basic for Applications and MATLAB to automate this process and allow for optimisation of the RFQ design parameters based on particle dynamical considerations. Initial particle tracking simulations based on modifying the field map from the Front-End Test Stand (FETS) RFQ design have determined the best operating frequency for the PAMELA RFQ to be close to 200 MHz and the length approximately 2.3 m. The status of the injector design with an emphasis on the RFQ will be presented, together with the results of the particle tracking.
LANL, Los Alamos, New Mexico
We are developing high-efficiency room-temperature RF accelerating structures based on inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. Such IH-PMQ accelerating structures following a short RFQ can be used in the front end of ion linacs or in stand-alone applications such as a compact deuteron-beam accelerator up to the energy of several MeV. New results from our detailed electromagnetic 3-D modeling combined with beam dynamics simulations and thermal-stress analysis for a complete IH-PMQ accelerator tank, including the end-cell design, will be presented.
NSCL, East Lansing, Michigan
Funding: This work is supported by the U.S. Department of Energy
The superconducting (SC) driver linac developed for the proposed Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) will be able to accelerate stable beams of heavy ions to > 200 MeV/u with beam powers up to 400 kW. The driver linac front-end will include ECR ion sources, a bunching system for multi-charge state beams and a radio frequency quadrupole (RFQ). The superconducting linac will have a base frequency of 80.5 MHz primarily using SC cavities and cryomodules developed for the Rare Isotope Accelerator (RIA), the FRIB predecessor. A charge-stripping chicane and multiple-charge state acceleration will be used for the heavier ions in the driver linac. A beam delivery system will transport beam to the in-flight particle fragmentation target station. The paper will discuss recent progress in the accelerator system design for the superconducting driver linac.
RLNR, Tokyo
An Interdigital-H (IH) linac has been used for ion acceleration in low beta range. It can realize a resonant cavity of a convenient size at low frequencies and higher shunt impedance at low energy range. These characteristics are advantageous especially for heavy ion acceleration. Since the shunt impedance of the IH linac reduces according to the increasing of beam energy, the linacs operated by the TM010 mode such as an Alvarez type and a coupling cavity type are adopted for medium and high energy range. However, we propose the new IH linac using the TE11n mode, the higher order mode IH (HOM-IH) linac. By using the higher order mode, the resonance frequency is higher than that of the IH linac. This property is suitable for middle and high beta linacs, and a proton linac as well. The design of the cavity structure and the possibility are presented.
JINR, Dubna, Moscow Region
The current status of the JINR FLNR cyclotrons and plans of their modernization are reported. At present time, four isochronous cyclotrons: U400, U400M, U200 and IC100 are under operation at the JINR FLNR. The U400 and the U400M are the basic cyclotrons that are under operation about 6000 and 3000 hours per year correspondingly. Both the accelerators are used in DRIBS experiments to produce and accelerate exotic very neutron-rich isotopes of light elements such as 6He and 8He. The U400 (pole diameter of D=4 m) is designed to accelerate ion beams of atomic masses from 4 to 209 to maximum energy of 26 MeV/u for synthesis of the new super heavy elements and other physical experiments. The U400M cyclotron (D=4 m) is used to accelerate ions of elements from Li to Ar up to 50 MeV/u and heavier ions such as 48Ca, Kr,Xe, up to 6 MeV/u after recent modernization. The U200 cyclotron (D=2 m) is used to produce isotopes by using He ions with energies about 9 MeV/u, modernization of the cyclotron injection is planned. Modernized IC100 accelerator (D=1m) is used to produce track membranes and carrying out experiments in solid-state physics by using Ar, Kr and Xe ions at energies of 1.2 MeV/u.
JINR, Dubna, Moscow Region
In axial injection channels of FLNR JINR cyclotrons the axial symmetric ion beam is formed just after the analyzing bending magnet. This gives an opportunity to use for beam focusing at vertical part of the channel solenoidal magnetic lenses only. During the motion of intense axial symmetric beam in the longitudinal magnetic field of solenoids and cyclotron the transverse tunes Qx, Qy coincide. In this case the small disturbance of beam axial symmetry leads to excitation of coupling resonance Qx-Qy=0 due to beam self-fields. The influence of the resonance results in significant asymmetry of the transverse beam emittances. The magnitude of this asymmetry is evaluated within the framework of moments method and is in a good agreement with one obtained in the macro-particles simulation. The correction of resonance by means of the normal quadrupole lens is proposed.
JINR, Dubna, Moscow Region
IBA, Louvain-la-Neuve
C400 is compact superconducting cyclotron for hadron therapy. The permissible level of the transverse magnetic field at the horizontal part of axial injection beam line of a cyclotron is about 10 Gauss. At the same time the C400 magnetic field is about 500 Gauss in magnitude at the places of the ion sources, vertical bending magnet and quadrupole lens location. Thereby the screening of these beam-line elements is needed. The 3D OPERA model of the cyclotron and channel elements is used for this purpose.
JINR, Dubna, Moscow Region
IBA, Louvain-la-Neuve
C400 is compact superconducting isochronous cyclotron for carbon beam therapy designed by IBA, Louvain-La-Neuve (Belgium) in collaboration with JINR, Dubna (Russia). The cyclotron can accelerate all ions with charge to mass ratio 0.5. Protons are accelerated as single charge 2H+ molecules and extracted by stripping at 270 MeV. All other ions are extracted by an electrostatic deflector at 400 MeV/u. The final layout of the axial injection beam line of C400 cyclotron is given. Two ion sources for production of 12C6+ ions and Alphas beams are located at the horizontal part of the channel before both side of the combination vertical magnet. The third ion source for the production of 2H+ is placed in straight line on the vertical axis. The rotational symmetry of the beam is reestablished with the help of one quadrupole lens placed just after analyzing magnet. The beam focusing at the vertical part of the channel is provided by three solenoidal lenses instead of four quadrupoles used in the previous version of beam line. The results of simulation of ion beams transport in the axial injection channel are presented.
CIAE, Beijing
TRIUMF, Vancouver
Department of Physics, Central China Normal University, Wuhan
There is increasing interest in high current compact H- cyclotrons for RIB, isotope production or as injectors for sub-critical reactor testing facilities. For compact cyclotrons, a practical limit on the output energy, to prevent significant Lorentz stripping and resulting activation, is ~100 MeV. Vacuum dissociation is another critical problem, because a compact structure and small parts inside the tank make high vacuum challenging. This paper describes how Lorentz stripping and vacuum dissociation were calculated for our “CYCIAE-100” under construction. In order to take into account non uniform magnetic fields and vacuum, losses were calculated by numerically integrating loss equations along tracked orbits, as these were being calculated by the beam dynamics code. To verify the code, losses derived with field and vacuum data from the TRIUMF 500 MeV cyclotron were compared with measurements. For the CYCIAE-100 cyclotron we predict that electromagnetic losses will account for less then 0.3% of total beam, vacuum losses for less than 0.58%, with peak magnetic fields up to 1.35T and average vacuum up to 5·10-8 Torr.
UBC & TRIUMF, Vancouver, British Columbia
It is sometimes asserted that Thomas's proposal to provide additional axial focusing in cyclotrons (to enable them to operate isochronously at relativistic energies) by introducing an azimuthal variation in the magnetic field was an early example of alternating-gradient focusing. While Thomas cyclotrons certainly exhibit alternating field gradients, it is shown that the alternating focusing produced is very much weaker than the edge focusing (everywhere positive) arising from orbit scalloping.
ANL, Argonne
Funding: This work was supported between the UChicago, Argonne, LLC and the Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
We have designed a compact high-resolution isobar separator for CARIBU* at the ATLAS accelerator facility at Argonne National Laboratory. Fission fragments from a 252Cf source are thermalized, cooled, and accelerated to 50 keV. The small longitudinal emittance of this cooled beam allows the use of pure magnetic dispersion for mass analysis. Using two 60° bending magnets, two electrostatic quadrupole doublets, and two electrostatic quadrupole singlets in a symmetric combination, a first-order mass resolution of 22,400 is calculated. Aberration correction up to 5th order is accomplished by means of two electrostatic hexapole singlets and a 48-rod electrostatic multipole lens with hexapole, octupole, decapole, and dodecapole components. The fields with critical tolerances are the quadrupole singlets (±1x10-3) and the hexapole component of the multipole (±2x10-3). Ion-optics calculations were performed using the program COSY INFINITY**. The resulting ion trajectories and mass spectra will be presented. All electrostatic elements have been constructed, and delivery of the magnets is expected in early 2009. A progress report on installation and commissioning will be presented.
*See invited talk by R. Pardo at this conference.
**Version 8.1, M. Berz et al., (2002).
DAE/VECC, Calcutta
UGC DAE CSR, Kolkata
An ISOL post-accelerator type of Rare Ion Beam (RIB) facility is being developed at our centre. The facility will use light ion beams from the K=130 cyclotron for producing RIBs using suitable thick targets. Also, development of an electron LINAC has been initiated with an eye to produce RIBs using the photo-fission route. The RIBs will be ionized, mass separated and the RIB of interest will be accelerated using a four rod Radio Frequency Quadrupole from 1.7 to 98 keV/u. The posts, vanes and base plate of the RFQ have been machined from OFC copper and the cavity is made from steel with its inner surface plated with copper. Oxygen beam of charge state 5+ has already been accelerated with an efficiency of around 90% through the RFQ. The first IH LINAC will accelerate RIBs up to about 186 keV/u. The octagonal shape LINAC cavity is made from explosively bonded copper cladded steel. Low power tests of the LINAC is encouraging - the beam test is scheduled for January 2009 and the results of which will be reported. The R&D efforts in various areas of this project will be discussed in this paper. Special emphasis will be given to the development of the RFQ and LINAC.
GSI, Darmstadt
The main purpose of the Recuperated Experimental Storage Ring (RESR) in the FAIR project is the accumulation of antiprotons coming from the Collector Ring (CR), where they are stochastically pre-cooled. The accumulation scheme in the RESR foresees longitudinal stacking in combination with stochastic cooling. The stochastic cooling process strongly depends on the slip factor η of the ring. Presently, the RESR is designed to operate with small slip factor of 0.03. In order to increase the flexibility for optimized stochastic cooling a new alternative ion-optical mode with higher slip factor of 0.11 has been calculated in such a way, that the RESR can be operated with a fixed magnetic structure in both modes. The influence of the high-order chromaticity on the particle motion has been investigated and a chromaticity correction scheme is applied. The variation of the transition energy over the momentum acceptance was examined and the possibility of its correction is described.
TU Darmstadt, Darmstadt
CERN, Geneva
The REX-ISOLDE radioactive ion beam facility at CERN makes great demands also on the experimentalists due to its specific duty cycle and the time structure with short beam pulses and large intensities. This paper describes the experimentalist's point of view, how to obtain sufficient and correct statistics under the special circumstances arising from the beam time structure. In particular, the case of Coulomb excitation experiments, where a large total cross section is ultimately desired, is studied in greater detail.
NSCL, East Lansing, Michigan
The Facility for Rare Isotope Beams (FRIB) will provide intense beams of short-lived isotopes for fundamental research in nuclear structure and nuclear astrophysics. Operation of the facility requires intense uranium primary beams. At the present time acceleration of two simultaneous charge states of uranium from a single ion source is needed to achieve the required intensity. Three schemes are considered for funneling the beams from two sources as an alternate solution. One is the traveling wave RF kicker for merging of bunched beams extracted from ECR ion sources. Another one implements the idea of utilizing an RFQ for beam merging*, which can be used after preliminary acceleration of both beams. The third approach assumes usage of a conventional standing-wave RF kicker. Parameters of all three schemes are compared and analyzed.
*R.H.Stokes and G.N.Minerbo, AIP Conference Proceedings 139 (1985), p.79.
NSCL, East Lansing, Michigan
Cyclotron gas stopper is a newly proposed device to stop energetic ions in a high pressure helium gas and to transport them in a singly charged state with a gas jet to a vacuum region. Radioactive ions are slowed down by gas collisions inside the field of a weakly focusing cyclotron-type magnet and extracted via interaction with the Radio Frequency field of sequence of concentric electrodes (RF carpet). The present study focuses on a detailed understanding of space charge effects in the central ion extraction region. Such space charge effects originate from the ionization of the helium gas during the stopping of the ions and are the cause for beam rate limitations. Particle-in-cell simulation of two-component (electron-helium) plasma interacting via Coulomb forces were performed in a field created by ionized ions. Simulation results indicate beam rate capabilities and efficiencies far beyond those achieved with linear gas cells presently used to stop projectile fragments.
ORNL, Oak Ridge, Tennessee
Funding: *Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
HRIBF produces high-quality beams of short-lived radioactive isotopes for nuclear science research, and is currently unique worldwide in the ability to provide neutron-rich fission fragment beams post-accelerated to energies above the Coulomb barrier. HRIBF is undergoing a multi-phase upgrade. Phase I (completed 2005) was construction of the High Power Target Laboratory to provide the on-going Isotope Separator On-Line development program with a venue for testing new targets, ion sources, and radioactive ion beam (RIB) production techniques with high-power ORIC beams. Presently under way is Phase II, the Injector for Radioactive Ion Species 2, a second RIB production station that will improve facility reliability and accommodate new ion sources, RIB production, and RIB purification techniques, including laser applications. The Phase III goal is to substantially improve facility performance by replacing or supplementing the Oak Ridge Isochronous Cyclotron production accelerator with either a high-power 25-50 MeV electron accelerator or a high-current multi-beam commercial cyclotron. Either upgrade is applicable to R&D on isotope production for medical or other applications.
PKU/IHIP, Beijing
Funding: work supported by NSFC(10805003,10855001)
The beam commissioning of Separated Function RFQ (SFRFQ) accelerator, which can gain high accelerating efficiency and enough focusing strength for low energy high current beam, is presented. In order to demonstrate the feasibilities of this novel accelerator, a prototype cavity was designed and constructed. The O+ beam was accelerated from 1MeV to 1.6MeV by SFRFQ cavity. A triplet was constructed for the transverse beam matching between the 1MeV ISR-RFQ 1000 and SFRFQ. A capacitance frequency tuning system and RF phase shifter were used to keep SFRFQ cavity working at the same frequency of ISR RFQ at the right phase. The whole RFQ accelerator system and the preliminary beam test results are presented in this paper.
TRIUMF, Vancouver
The ISAC facility, located at TRIUMF, first began delivering radioactive ion beams (RIBs) in 1998, added post-accelerated beam capability in 2001, and is regarded as one of the premiere RIB facilities in the world. The existing constraints on RIBs of Z<83 and accelerated beams of A/q<30 with energies limited to 5MeV/u are being addressed. A charge-state booster for RIBs has been commissioned to alleviate the A/q<30 restriction and has successfully delivered multi-charge beams through the ISAC accelerators. The 5MeV/u license limit will be removed once an on-line beam monitor is commissioned, allowing beams of up to 11MeV/u to be delivered presently, and increased to over 20MeV/u when the next accelerator phase is installed. In 2008, an actinide target was used to produce RIBs of Z>82; this successful test was performed on a uranium target with yields measured and radiation safety monitored. A new Beam Delivery group has been formed to integrate all aspects of RIB production, which has led to improved efficiency and greater experimental results. These new capabilities will be presented, showing how 2009 promises to be both an exciting and productive year at ISAC.