CERN, Geneva
With LHC coming into operation very soon an upgrade plan for the whole CERN accelerator complex has been proposed to allow full exploitation of the LHC potential in the future as well as giving increased support to traditional and possible new experiments at lower beam energies. This plan foresees replacing during the period 2011 - 2017 all the accelerators in the LHC injector chain (Linac2, Booster, PS) by new machines (Linac4, SPL and PS2) except for the last - the SPS. In this scenario the SPS should be able to reliably accelerate twice higher beam intensity than achieved so far and therefore significant improvements to the machine performance, in addition to the increased injection energy due to PS2, should be found and implemented at the same time scale. The present status of proposals and ongoing studies for all accelerator injector chain is described with main emphasis on the SPS challenges and upgrade plans.
Fermilab, Batavia, Illinois
Understanding the behavior of high-intensity beams in the Fermilab Main Injector is crucial for the future physics program at the lab. Simulations of the Main Injector including collective effects are a crucial part of this understanding. We are building up a set of integrated simulations of collective effects using the Synergia accelerator simulation framework. As a step in this work we present simulations of space-charge effects combined with impedance effect in the Main Injector.
Fermilab, Batavia, Illinois
BNL, Upton, Long Island, New York
Beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and the principle is now being experimentally investigated at RHIC. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, we do simulations to study the effect of wire compensator based on diffusive apertures, beam loss rates, and beam transfer function using a parallel weak-strong beam simulation code (bbsimc) without parasitic collisions. The simulation results are compared with measurements.
BNL, Upton, Long Island, New York
A strong interest in running RHIC at low energies in a range of 2.5-25 GeV/nucleon total energy of a single beam has emerged recently. Providing collisions in this energy range, which in RHIC case is termed “low-energy” operation, will help to answer one of the key questions in the field of QCD about existence and location of critical point on the QCD phase diagram. To evaluate the challenges of RHIC operation at such low energies there have been several short test runs during RHIC operations in 2006, 2007 and 2008. The beam lifetime observed during the test runs was clearly limited by machine nonlinearities. This performance can be improved provided sufficient time is given for machine development at these low energies. After the lifetime caused by nonlinearities is improved the strongest limitation comes from transverse and longitudinal Intra-beam Scattering (IBS), and ultimately by the space-charge limit. A significant luminosity improvement can be provided with electron cooling applied directly in RHIC at low energies. This report summarizes various beam dynamics limiting effects and possible improvement with electron cooling.
Fermilab, Batavia, Illinois
Coupling between different degrees of freedom complicates analysis of beam dynamics in a ring. Nevertheless appropriate choice of dynamic variables often allows reducing a problem to uncoupled case. Effects of coupling on the beam instabilities and their damping are considered. As examples the X-Y coupling in Tevatron and the coupling of longitudinal and horizontal motion in FNAL Booster are considered.
GSI, Darmstadt
Resonant effects caused by space charge may occur in circular as well as linear accelerators for high intensity. In the present work we focus on the so-called space charge structure resonances in 2D approximation, where the driving force is induced by space charge only (emittance exchange, fourth and sixth order structure resonances) and show that they can be described by a common class of scaling laws. A distinctive feature is the presence or absence of trapping of particles, which is also reflected in the power of the scaling law. An important requirement is the fully self-consistent modeling, which describes correctly the evolution of beam core as well as halo.
IUCF, Bloomington, Indiana
Fermilab, Batavia, Illinois
Scaling laws of the emittance growth factor (EGF) for a beam crossing the 6th order systematic space-charge resonances and the random 4th order resonance driven by octupoles are obtained by numerical multi-particle simulations. These scaling laws can be used in setting the minimum acceleration rate, and the maximum tolerable resonance strength for the design of non-scaling fixed-field alternating gradient (FFAG) accelerators.
GSI, Darmstadt
In the talk we report on an extensive experimental campaign performed at GSI on the SIS18 synchrotron. We measured the evolution of beam properties over 1 second storage of several beams for several working points in the vicinity of a machine resonance. With this data we benchmark our code predictions and test the understanding of the underlying beam degradation mechanisms.
KEK, Ibaraki
The J-PARC Main Ring should provide high beam power with strict limitation of the particle losses during the operation, including the injection and acceleration processes,caused by the machine imperfections and the space charge effects. The linear coupling resonance [1,1,43] has been identified as the most serious resonance for the MR operation, which leads to significant particle losses during the injection process. Effect of the sextupole resonances, caused by the machine imperfection, is much smaller. The 4th order resonances, mainly 4Qx, 4Qy and 2Qx-2Qy, excited by the space charge of the low energy beam, lead to additional particle losses. The correction procedure to minimize the effect of the sum coupling resonance [1,1,43] by using four independent skew quadrupole magnets has been studied. The particle losses for different machine operation scenario have been estimated, including the injection and acceleration processes. The study of the combined effect of the MR imperfections and the space charge of the beam with moderate beam power has been performed by using the PTC_ORBIT code, installed for the KEK super computer HITACHI SR11000.
CERN, Geneva
Recent developments relative to the injection and storage of the 160 MeV Linac4 high brightness beam for LHC into the CERN PS Booster are reviewed. This talk reports simulations made with the Orbit code. Focus is on H- charge exchange injection and following beam emittance evolution at 160 MeV. Injection is done via a painting scheme for optimal shaping of the initial particle distribution. Next, benchmarking of Orbit and Accsim simulations with measurements performed in the PS Booster on a stored beam at 160 MeV are discussed.
BNL, Upton, Long Island, New York
Intra-beam scattering (IBS) is the limiting factor of the luminosity lifetime for RHIC operation with heavy ions. Over the last few years the process of IBS was carefully studied in RHIC with dedicated IBS measurements and their comparison with the theoretical models. Recently, in order to suppress transverse IBS growth, a new lattice was designed and implemented in RHIC, which lowered the average arc dispersion by 30%. This lattice became operational during RHIC Run-8. We review the IBS suppression mechanism, IBS measurements before and after the lattice change, and comparisons with predictions.
CERN, Geneva
In the CERN Proton Synchrotron (PS), a slow beam loss of few percents is still observed on the long injection flat-bottom with the nominal beam for LHC after fine tuning of the working point. The understanding of space-charge effects is therefore of paramount importance to try and alleviate this limitation. This is why controlled benchmarking space-charge experiments were performed in the last few years. The results are presented in detail with a particular emphasis on the maximum achievable space-charge tune shift with long lifetime. On the contrary, space-charge effects usually play a minor role in high-energy machines like the CERN Super Proton Synchrotron (SPS). However, they could potentially become a limitation for the heavy ion beams needed for the LHC. Therefore, experimental studies on space-charge limitations were also performed in the SPS in the last few years. The results are discussed in detail in the present paper. Furthermore, it is worth mentioning that observations similar to the ones measured in the PS in the presence of space-charge were also measured in the SPS with electron cloud.
ORNL, Oak Ridge, Tennessee
LBNL, Berkeley, California
Multi-particle tracking simulations for the SNS linac beam dynamics studies are performed with the IMPACT code. Beam measurement results are compared with the simulations, including beam halos and beam loss in the superconducting linac, measurement of beam transverse twiss parameters and beam longitudinal emittance in the SNS linac. And in most cases, the simulations show good agreement with the measured results.
GSI, Darmstadt
ORNL, Oak Ridge, Tennessee
CEA, Gif-sur-Yvette
Systematic measurements on transverse rms-emittance growth along the Alvarez DTL of the GSI UNILAC were performed. A high intensity argon beam was used to measure rms-growth for different transverse phase advances along the DTL. The transverse tune depression varied from 21% to 43%. For benchmarking of the experimental results four different beam dynamics codes were used: DYNAMION, PARMILA, PARTRAN, and LORASR. This paper is on the results of the experiments, the reconstruction of the initial conditions for the simulations, and on the agreement between simulations and experiments. Additionally, successful suppression of rms-growth by systematic matching is reported.
ANL, Argonne, Illinois
Fermilab, Batavia, Illinois
Large-scale beam dynamics simulations are important in accelerator design and optimization. With the new BG/P supercomputer installed at ANL, tera-scale computing can be easily accessed. In order to make use of this emerging technology to increase the speed and efficiency of accelerator simulations, we have systematized and upgraded our software. In this paper, we will first introduce the new version of the parallel beam dynamic code PTRACK [1] updated to run on BG/P with more than 104 processors. The new PTRACK includes possibility to track ~100,000,000 particles through multiple accelerator seeds in the presence of machine errors. An example of SNS linac simulations will be presented.
[1]. J. Xu, B. Mustapha, V.N. Aseev and P.N. Ostroumov, “Parallelization of a beam dynamics code and ***”, Physics Review Special Topic-Accelerator and Beams 10, 014201, 2007.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
The beam commissioning of J-PARC linac has been started since November 2006. Numerical studies have been conducted since then to analyze the experimental results obtained in the beam commissioning and deepen our understanding on the underlying physics. Particular efforts are exerted on the analyses of the transverse emittance measurement at MEBT, the phase scan measurement for DTL, and the rms width response to a quadrupole magnet variation. All the measurements are essential to realize a fine tuning of the linac, and it is of practical importance to have a physical insight into the obtained results. In these studies, various simulation tools are employed in accordance with the required capacity. In this paper, the on-going numerical studies for J-PARC linac are reviewed, and we discuss on the directions in which we should pay further efforts.
ORNL, Oak Ridge, Tennessee
GSI, Darmstadt
The 4ν=1 resonance of a linac is found when the depressed tune is around 90 deg. It is observed that this fourth order resonance is dominating over the better known envelope instability and practically replacing it. Simulation study shows a clear emittance growth by this resonance and its stopband. Experimental measurement of the stopband of this resonance is proposed and conducted in 2008 using the UNILAC at GSI. This study will serve as an excellent benchmarking.
SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
CERN, Geneva
CEA, Gif-sur-Yvette
Linac4 is a normal conducting H- linac to be built at CERN as a new injector to the PS Booster and later on as a front end of a possible MultiMegaWatt Linac Facility. The layout consists of a H- RF source, a magnetic LEBT, a RFQ (accelerating the beam from 45 keV to 3 MeV), a chopper line, a conventional Drift Tube Linac (from 3 MeV to 50 MeV), a Coupled Cavity Drift Tube Linac (from 50 MeV to 100 MeV) and a pi-mode structure (PIMS, from 100 to 160 MeV), all operating at a frequency of 352 MHz. End-to-end beam dynamics simulations have been carried out to optimise the design and performance of the accelerator. An extensive statistical campaign of transverse error studies was then launched for accessing the required alignment tolerances and steering correction system.
ANL, Argonne, Illinois
Matrix-based beam optics codes such as TRACE-3D are often used for small scale optimizations such as beam matching which involves a limited number of parameters. The limitation of such codes is further amplified for high-intensity and multiple charge state beams as their predictions start to deviate from the more realistic 3D particle tracking codes. For these reasons we have started developing large scale optimization tools for beam tracking codes. The large scale nature comes first from the possibility of optimizing a large number of parameters and second from the minimum number of particles to track especially for space charge dominated beams. The ultimate goal of these developments is not only to optimize the design of an accelerator but also to be able to use a beam dynamics code to operate it once built. A selected set of optimization options will be presented and discussed along with specific applications. We'll also emphasize the need for parallel computing to speed-up the optimization process.
ORNL, Oak Ridge, Tennessee
With the increase of average power of present and future high intensity proton rings and rapid progress of laser technology, laser-assisted stripping become a real alternative for carbon foils that are used for charge-exchange injection. High efficiency laser stripping, achieved experimentally at Spallation Neutron Source in Oak Ridge, TN, paved the way to full scale devices of such type. This paper presents overview of machines and choices of parameters for future powerful accelerators with possible laser stripping use.
Fermilab, Batavia, Illinois
Fermilab plans to boost the power of Main Injector beam to about 2 MW by building a new SC 8 GeV linac. Its H- beam will be strip injected and accumulated in upgraded Recycler ring, and then transferred to Main Injector for further acceleration to 120 GeV. Beam physics issues related to high intensity operation of Recycler ring and Main Injector are considered.
CERN, Geneva
The construction of a Superconducting Proton Linac is planned at CERN during the next decade. It is foreseen to be constructed in two stages: a low duty cycle, low-power linac (LPSPL) as an injector for a new 50 GeV synchrotron (PS2) replacing the present PS, which could be upgraded to a high-duty cycle, high-power linac (HPSPL), for the needs of future facility(ies) requiring a multi-MW beam power. In this paper we present the criteria which were used to choose the frequency, gradient, and cryogenic temperature of the SPL. Since these questions are common to other proposed high-power proton linacs, we propose a generalization of the arguments. The various design options are discussed as well as their impact on beam dynamics, cavity performance, power consumption, cryogenics, overall efficiency, and cost of the facility.
Muons, Inc, Batavia
Fermilab, Batavia, Illinois
Muon colliders and neutrino factories impose demanding requirements on the proton accelerator systems that are used to produce the muons. Various concepts to meet those needs have been developed. A scheme that uses a powerful 8-GeV H- linac followed by storage rings for accumulation and bunch manipulations will be described and compared with other ideas.
RIKEN/RARF/CC, Saitama
RIKEN Nishina Center, Wako, Saitama
ANL, Argonne, Illinois
The accelerator complex for RIBF factory in RIKEN consists of the four ring cyclotrons with an injector linac. It can boost the energy of output beams from the linac up to 440 MeV/nucleon for light ions and 350 MeV/nucleon for very heavy ions. The first beam from the accelerator complex was successfully extracted at the end of 2006. An 28GHz SC-ECR ion source will be installed at the front end of the injector linac on a 100kV HV platform to increase the beam intensity of very heavy ions such as uranium. Beam dynamics from the ion source to the exit of the injector were simulated using TRACK. How much space charge forces affect on beam qualities in the successive ring cyclotrons will be discussed.
ORNL RAD, Oak Ridge, Tennessee
ORNL, Oak Ridge, Tennessee
Space charge effect has an impact on emittance measurement of low energy H- ion beam injected into the SNS RFQ. This paper presents numerical investigations of space charge effect of the beam on transverse emittance measurement using an Allison style scanner attached to the front-end test stand at SNS. The investigations are based on mathematical modelling the emittance measurement by the scanner taking into account space charge of the beam. We present a method of emittance data analysis that includes the modelling and allows more accurate measurements of the emittance. We also give an example of the emittance measurement with the scanner applying the developed method.
STFC/RAL, Chilton, Didcot, Oxon
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
In order to contribute to the development of high power proton accelerators in the MW range a front end test stand (FETS) is being constructed at the Rutherford Appleton Laboratory (RAL) in the UK. The aim of the FETS is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. Therefore a comprehensive set of diagnostic tools have been developed or are in the design and construction phase. To improve the beam quality delivered by the Penning H- ion source using a slit extraction, a pepper pot emittance measurement device and a 2D-transversal profile scanner has been built and used on the ion source development rig and results of the beam measurements will be presented. As destructive diagnostic devices suffer from the high beam power deposited on the device surfaces, two new diagnostic devices based on the photo detachment principle are under construction: A laser wire scanner allowing the reconstruction of the full 2D-transversal density distribution using tomographic techniques and an emittance scanner device. The design and status of construction of both devices will be presented and new ideas for the data analyses discussed.
CIEMAT, Madrid
CEA, Gif-sur-Yvette
The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. It is essential then to implement the necessary instrumentation for the commissioning and operation of the accelerator prototype, as well as for a correct characterization of the beam properties. A set of instrumentation will be installed in the last part of the accelerator, at the first section of the High Energy Beam Transport Line (HEBT), between the superconducting HWR and the Beam Dump (BD), in the so-called Diagnostics Plate (DP) to fully characterize the beam properties both from the RFQ and the HWR. In addition, there will be dedicated diagnostics all along the HEBT to transport and control the beam safely down to the BD. Moreover, the closest area to the BD with high radiation levels and big pipe aperture- can be used for the tests of IFMIF profilers. In this contribution the requirements imposed by the high-intensity deuteron accelerator to the instrumentation along the HEBT, the type of techniques that will be used and a preliminary layout and specifications of the diagnostics in the line will be presented.