CERN, Geneva
Beam commissioning of the LHC started with injection tests in August 2008, and a circulating beam was obtained in little over 3 days in September 2008. Unfortunately a powering incident in one the eight LHC sectors set an abrupt end to the beam commissioning in 2008. This talk will review the LHC beam commissioning achievements. It will describe the repair the LHC sector affected by the incident and present the measures that have been taken to avoid similar incidents in the future. The commissioning steps foreseen for the 2009 run and towards LHC design performance will be outlined.
CLASSE, Ithaca, New York
Fermilab, Batavia
Cornell University is planning to build an Energy-Recovery Linac (ERL) X-ray facility. In this ERL design, a 5 GeV superconducting linear accelerator extends the CESR ring which is currently used for the Cornell High Energy Synchrotron Source (CHESS). Here we describe some of the recent developments for this ERL, including linear and nonlinear optics, tracking studies, vacuum system design, gas and intra beam scattering computations, and collimator and radiation shielding calculations based on this optics, undulator developments, optimization of X-ray beams by electron beam manipulation, technical design of ERL cavities and cryomodules, and preparation of the accelerator site.
ELETTRA, Basovizza
B.I. Stepanov Institute of Physics, Belarus
Funding: The work was supported in part by the Italian Ministry of University and Research under grant FIRB-RBAP045JF2
Particle accelerator and laser technologies are effectively combining with each other in the development of next generation light sources, with the latter being one of the key factors determining the ultimate performance of these machines. VUV and X-FEL facilities take advantage of laser technology at many strategic points: creation of the electron bunch (photo-injector laser), acceleration (laser heater), undulators (seed laser), beam diagnostics (electro-optic sampling lasers), user experiments (pump-probe lasers). The talk will discuss the main requirements and challenges (photoinjector and seed lasers in particular) for the laser systems and will illustrate proposed solutions and obtained results. Recent laser achievements that are likely to have impact on important developments like high average power injectors, different guns,tunable short wavelength FEL seeding will also be addressed.
CERN, Geneva
The start-up of the LHC has provided the first field test for the concept, functionality and accuracy of FiDeL, the Field Description for the LHC. FiDeL is primarily a parametric model of the transfer function of the main field integrals generated by the series of magnets in the LHC powering circuits, from main optical elements to high-order harmonic correctors, both superconducting and normal-conducting magnets. In addition, the same framework is used to predict harmonic errors of both static and dynamic nature, and forecast appropriate corrections. In this paper we give a description of the level of detail achieved in the model and the rationale adopted for the LHC start-up. Beam-based measurements have been used for an assessment of the first-shot accuracy in the prediction of the current setting for the main arc magnets*.
*The work reported has been performed by the authors and the FiDeL Team
Muons, Inc, Batavia
NHMFL, Tallahassee, Florida
Funding: Supported in part by DOE SBIR grant DE-FG02-08ER85024
Optical fibers can be imbedded within new high temperature superconductor (HTS) magnets to monitor strain and temperature, to detect quenches, and, in the case of AgX/Ag/Bi2Sr2CaCu2Ox, (Bi2212) wire magnets, to serve as a heat treatment process monitor for wind-and-react (W&R) manufacturing. The W&R process requires that the optical fibers be installed before the Bi2212 heat treatment, one important issue is whether the fibers survive the 890 oC heat treatment so as to monitor the heat treatment and to serve subsequently as a low temperature monitor. Here, Au-coated optical fibers are attached to Bi2212 wires and processed with the typical reaction cycle. The Bi2212 superconductor is then evaluated for performance degradation due to the presence of the fiber and the fiber is evaluated for performance degradation due to the heat treatment and viability as a heat treatment process monitor. Two approaches to fiber optic sensing are used: a fiber Bragg grating and Rayleigh scattering
LBNL, Berkeley, California
Electron microscopes and streak cameras are "mini accelerators". Advanced techniques in electron optics have been successfully applied to the design and optimization of electron microscopes and streak cameras. This talk is an overview of the status and unique designs that have arisen, with emphasis on the theoretical aspects.
BESSY GmbH, Berlin
PTB, Berlin
The Metrology Light Source (MLS)* is in user operation since April 1st, 2008. It is the first storage ring designed and built for operation in the low α mode, which relies on the control of higher order terms of the momentum compaction factor α with respect to the momentum deviation dp/p, α=a0+a1*dp/p+a2*(dp/p)**2. The a0 term is controlled by quadrupoles, a1 by 3 families of sextupoles for controlling the chromaticity in the transverse and longitudinal planes, the a2 term is controlled by an octupole family. The a0 value can be varied by more than a factor of {10}00. The low α mode is also called 'isochronous' operation, it is used for short bunch operation, where intense signals of coherent sub-THz radiation are produced. We report on operation experience of this scheme.
*R. Klein et al., 'Operation of the Metrology Light Source as a primary radiation source standard',
PHYSICAL REVIEW SPECIAL TOPICS - ACCELERATORS AND BEAMS 11, 110701 (2008).
FZK, Karlsruhe
The ANKA storage ring is filled at 0.5 GeV and then ramped to 2.5 GeV for regular user operation. A full-energy injection of the ANKA storage ring would have several advantages. The damping at a beam energy of 2.5 GeV is stronger, which will more efficiently fight instabilities during the injection, therefore allowing higher beam currents. With constant magnet settings, the orbit stability would improve significantly. The injection time would be reduced and topping- up operation would become possible. As a consequence, the optical elements of the user beamlines would see a constant power as a function of time which further enhances the overall stability. In this paper, a design for a full energy injector is proposed. The injector will be located inside the storage ring tunnel, similar to the SLS and ALBA design. The focusing is mainly provided by combined function magnets. The full energy injector has a design emittance of 40 nmrad and a circumference of 94.8 m. A modification of the existing storage ring is foreseen to house the necessary more powerful injection elements.
FZK, Karlsruhe
Ruhr-Universität Bochum, Bochum
KIT, Karlsruhe
A linac based coherent radiation source in the THz to mid-IR range is proposed. The TBONE machine will deliver pulses of radiation as short as a few fs in the frequency range from 0.1 to 150 THz with up to MW peak power. This combination of parameters will open up unprecedented opportunities in THz and infrared applications, such as e.g. microscopy or spectroscopy. This paper presents the main parameters and design considerations. Special emphasis is put on the study of suitable bunch compression and beam transport schemes.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The X-ray Free Electron Laser Oscillator* (XFEL-O) is a concept for a high-brightness fourth-generation x-ray source with full spatial and temporal coherence. It is based on a CW electron source and superconducting linac. In order to reduce cost and increase versatility, a recirculating linac configuration is being entertained. In this paper, we present an optics design for the four-pass linac and the three recirculation systems. The design goals are preservation of the beam emittance and energy spread, as well as minimal cost and complexity. We also present the results of tracking studies that show the expected performance.
*K.J. Kim et al., Phys. Rev. Letters, to be published.
ISSP/SRL, Chiba
JAEA/ERL, Ibaraki
KEK, Ibaraki
A compact ERL (energy recovery linac) is planned in Japan in order to demonstrate excellent ERL performances and to test key components such as low-emittance photocathode gun and superconducting RF cavity. We studied and optimized the compact ERL optics (except the injector part) to generate a subpico-second bunch in bunch compression mode and to preserve the beam emittance in normal and low-emittance mode. As a result, we could obtain a very short bunch of about 50 fs with a charge of 77 pC in bunch compression mode and almost keep the normalized emittance of 0.1 mm mrad with a charge of 7.7 pC in low-emittance mode. We also designed it to achieve efficient energy recovery at the superconducting RF cavities and to transport the beam to the dump section without serious loss. The design study of the compact ERL optics was carried out with the simulation code Elegant, including CSR(coherent synchrotron radiation) effects. In this paper, we will present the results of the beam optics study for the compact ERL.
CERN, Geneva
Following a series of injection tests, the first attempts to pass beam around both directions of the LHC were successful and led rapidly to circulating beam in the counter clockwise direction (beam 2) and many turns of beam 1. Unfortunately the beam commissioning was curtailed by the incident in sector 34. However, measurements performed during this first commissioning period should that the magnet model of the machine had delivered optics close to nominal, and also very good performance of beam instrumentation and supporting software. Details of the machine set-up and the commissioning procedures are detailed. The measurements performed and the key results from this period are described.
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.
CERN, Geneva
The LHC injection tests and first turn beam commissioning took place in late summer 2008, after detailed and thorough preparation. The beam commissioning of the downstream sections of the SPS-to-LHC transfer lines and the LHC injection systems is described. The details of the aperture measurements in the injection regions are presented together with the performance of the injection related equipment. The measured injection stability is compared to the expectations. The operational issues encountered are discussed.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Since 2005, the Recycler has become the sole storage ring for antiprotons used in the Tevatron Collider. The operational role of the Antiproton Source has shifted exclusively towards producing antiprotons for periodic transfers to the Recycler. The process of transferring the antiprotons from the Accumulator to the Recycler has been greatly improved, leading to a dramatic reduction in the transfer time. The reduction in time has been accomplished with a net improvement in transfer efficiency and an increase in average stacking rate. This paper will describe the software improvements that streamlined the transfer process and other changes that contributed to a significant increase in the number of antiprotons available to the Collider.
KAERI, Daejon
Funding: This work is supported by the Ministry of Education, Science and Technology of Korea.
PEFP (Proton Engineering Frontier Project) beamlines will be supplied either 20-MeV or 100-MeV proton beams from the 100-MeV proton linear accelerator for beam applications. Each proton beam will be transported to 2 beamlines for industrial purpose and 3 beamlines for the researches. Beam distribution to 3 research beam lines will be conducted sequentially by programmable AC magnet. To provide flexibility of the irradiation conditions, each beam line is designed to have specific beam parameters. We have designed the beamlines to the targets for wide or focused beams, external or in-vacuum beams, and horizontal or vertical beams. The detail design of each beamline will be reported.
ORNL, Oak Ridge, Tennessee
Muons, Inc, Batavia
JLAB, Newport News, Virginia
Funding: Supported in part by USDOE Contract No. DE-AC05-84-ER-40150. Supported in part by USDOE Contract DE-AC05-00OR22725
The ORNL spallation neutron source (SNS) user facility requires a reliable, intense beams of protons. The technique of H- charge exchange injection into a storage ring or synchrotron has the potential to provide the needed beam currents, but it will be limited by intrinsic limitations of carbon and diamond stripping foils. A laser in combination with magnetic stripping has been used to demonstrate a new technique for high intensity proton injection, but several problems need to be solved before a practical system can be realized. Technology developed for use in Free Electron Lasers is being used to address the remaining challenges to practical implementation of laser controlled H- charge exchange injection for the SNS. These technical challenges include (1) operation in vacuum, (2) the control of the UV laser beam to synchronize with the H- beam and to shape the proton beam, (3) the control and stabilization of the Fabry-Perot resonator, and (4) protection of the mirrors from radiation.
SLAC, Menlo Park, California
BNL, Upton, Long Island, New York
Funding: Work supported by the US Department of Energy, Office of Basic Energy Sciences.
In the past, SPEAR3 has had typically 50 to 70% injection efficiency. Much of the lost injected beam hit the small gap vacuum chambers at the insertion devices. We are now implementing injection with photon beamline shutters open, so these losses create Bremsstrahlung down the photon beamlines, increasing radiation levels on the photon experimental floor. In this paper, we describe work done to better control the booster to SPEAR (BTS) transport line beam so as to reduce losses during injection. We have used new BTS BPM electronics to control the transport line trajectory. The trajectory response on these BPMs has been used to correct the BTS optics. We use turn-by-turn BPM readings of the injected beam in SPEAR to optimize the BTS trajectory in all six transverse and longitudinal coordinates. We use turn-by-turn profile measurements of the injected beam to verify the BTS optics correction. The stainless steel windows have been removed from the BTS vacuum system to reduce the transverse dimensions of the injected beam.
JLAB, Newport News, Virginia
ODU, Norfolk, Virginia
Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The CEBAF accelerator at Jefferson Lab has had, since first demonstration in 1996, the ability to deliver a 5-pass electron beam to experimental halls (A, B, and C) simultaneously. This capability was provided by a set of three, room temperature 499 MHz rf separators in the 5th pass beamline. The separator was two-rod, TEM mode type resonator, which has a high shunt impedance. The maximum rf power to deflect the 6 GeV beams was about 3.4kW. The 12 GeV baseline design does not preserve the capability of separating the 5th pass, 11 GeV beam for the 3 existing halls. Several options for restoring this capability, including extension of the present room temperature system or a new superconducting design in combination with magnetic systems, are under investigation and are presented.
SLAC, Menlo Park, California
Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515.
CMAD is a new code modeling the electron cloud effect driven instability by applying an electron-beam interaction at every element of a beam line, reading a MAD description of the accelerator optics as input. CMAD is parallelized and optimized for speed. It is especially suited for the modeling of incoherent electron-cloud effects for which the spatial distribution of electrons is particularly important. This talk will review the physics, describe the design concept, the present status, benchmarking exercises, and example applications.
JLAB, Newport News, Virginia
The College of William and Mary, Williamsburg
North Carolina State University, Raleigh, North Carolina
Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
As SRF cavities approach fundamental material limits, there is increased interest in understanding the details of topographical influences on performance limitations. Micro-and nano-roughness are implicated in direct geometrical field enhancements and complications of the composition of the 50 nm surface layer in which the super-currents flow. Interior surface etching (BCP/EP) to remove mechanical damage leaves surface topography, including pits and protrusions of varying sharpness. These may promote RF magnetic field entry, locally quenching superconductivity, so as to degrade cavity performance. A more incisive analysis of surface topography than the widely-used average roughness is needed. In this study, a power spectral density (PSD) approach based on Fourier analysis of surface topography data acquired by both stylus profilometry and atomic force microscopy (AFM) is being used to distinguish the scale-dependent smoothing effects. The topographical evolution of the varied starting state Nb surface (CBP/ EBW) as a function of applied etching, polishing steps and conditions is reported, resulting in a novel qualitative and quantitative description of Nb surface topography.
SLAC, Menlo Park, California
Funding: Work sponsored by U.S. Department of Energy Contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
Recent experimental results and advances in the theory of short-bunch dynamics have lead to an improved understanding of the parameters and limitations of short-bunch operation in storage rings. In this paper the measurement and analysis of short bunches under a variety of operational parameters is reported for SPEAR3.
SOLEIL, Gif-sur-Yvette
After two years of operation, the SOLEIL 3rd generation synchrotron light source is delivering photons to 20 beamlines with a current of 250mA in multibunch or hybrid modes, and 60 mA in 8 bunch mode. The radiation control of the beamline hutches is performed at 300 mA, but recently a 455mA current was stored during machine tests following the installation of the second RF cryomodule. It is foreseen to reach the maximum current of 500mA in the early 2009 and to operate in top-up mode from then on. The new transverse feedback loop has enabled to improve the performance of the single bunch and multibunch beams. The beam position stability is in the range of few micrometers thanks to the efficiency of the fast orbit feedback. Fifteen insertion devices are now installed in the storage ring, ten others are under construction, and a cryogenic undulator is under development. A big effort is being taken in order to compensate the effects of these insertion devices on the machine performance. The good operation performance achieved in 2007 (first year) has been improved in 2008 during which ~4 000 hours will have been delivered to the users with a 95.5% availability and a 30 hours MTBF.
BNL, Upton, Long Island, New York
The reduction of beta* beyond the 1m design value at RHIC has been consistently achieved over the last 6 years of RHIC operations, resulting in an increase of luminosity for different running modes and species. During the recent 2007-08 deuteron-gold run the reduction to 0.70 from the design 1 m achieved a 30% increase in delivered luminosity. The key ingredients in allowing the reduction have been the capability of efficiently developing ramps with tune and coupling feedback, orbit corrections on the ramp, and collimation at injection and on the ramp, to minimize beam losses in the final focus triplets, the main aperture limitation for the collision optics. We will describe the operational strategy used to reduce the b*, at first squeezing the beam at store, to test feasibility, followed by the operationally preferred option of squeezing the beam during acceleration, and the resulting luminosity increase obtained in the Cu-Cu run in 2005, Au-Au in 2007 and the deuteron-Au run in 2007-08. We will also include beta squeeze plans and results for the upcoming 2009 run with polarized protons at 250 GeV.
CERN, Geneva
The different levels of LHC collimators must be set up by respecting a strict setting hierarchy in order to guarantee the required performance and protection during the different operational machine stages. The available margins are a fraction of a beam σ. Two different sub-systems establish betatron and momentum collimation for the LHC. Collimator betatronic phase space cuts are defined for a central on-momentum particle. However, due to the chromatic features of the LHC optics and energy deviations of particles, the different phase space cuts become coupled. Starting from the basic equation of the transverse beam dynamics, the influence of off-momentum beta-beat and dispersion on the effective collimator settings has been calculated. The results are presented, defining the allowed phase space regions from LHC collimation. The impacts on collimation-related setting tolerances and the choice of an optimized LHC optics are discussed.
CERN, Geneva
We discuss luminosity monitoring, optimization and absolute calibration in the LHC. Interaction rates will be continuously monitored both by detectors on the machine side as well as by the four large LHC experiments. Horizontal and vertical separation scans will be used to optimize luminosity and to measure the beam sizes in the interaction region. An application software has been developed for this purpose. We describe the procedures which have been prepared and discuss expected systematic effects which may limit the accuracy of the measurement.
CERN, Geneva
The TOTEM experiment requires special high beta optics solutions. We report on studies of optics for an intermediate beta* = 90 m, as well as a solutions for a very high beta* of 1540 m, which respect all known constraints. These optics are rather different from the normal physics optics and will require global tune changes or adjustments.
Fermilab, Batavia
CERN, Geneva
ETH, Zurich
Funding: Work partly supported by Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
In the Large Hadron Collider LHC, particles not captured by the RF system at injection or leaking out of the RF bucket may quench the superconducting magnets during beam abort. The problem, common to other superconducting machines, is particularly serious for the LHC due to the very large stored energy in the beam. For the LHC a way of removing the unbunched beam has been studied and it uses the existing damper kickers to excite resonantly the particles travelling along the abort gap. In this paper we describe the results of simulations performed with MAD-X for various LHC optics configurations, including the estimated multipolar errors.
CERN, Geneva
The LHC beams will cross each other and experience perturbations as a result of the beam-beam effect at the interaction points, which can result in emittance growth and halo creation. The beam-beam force is approximately linear for small offsets and highly non-linear for larger offsets with peaks in growth close to 0.3 and 1.5 σ separation. We present a study of the process of going into collisions in the LHC and use simulations to investigate on possible emittance blow-up. We analyze how the crossing scheme can be optimized to minimize the collapsing time of the separation bumps for given hardware constraints.
CERN, Geneva
BNL, Upton, Long Island, New York
Various LHC injection tests were performed in August and early September 2008 in preparation for the circulating beam operation. These tests provided the first opportunity to measure with beam the available mechanical aperture in two LHC sectors (2-3 and 7-8). The aperture was probed by exciting free oscillations and local orbit bumps of the injected beam trajectories. Intensities of a few 109 protons were used to remain safely below the quench limit of superconducting magnets in case of beam losses. In this paper the methods used to measure the mechanical aperture, the available on-line tools, and beam measurements for both sectors are presented. Detailed comparisons with the expected results from the as-built aperture models are also presented. It is shown that the measurements results are in good agreement with the LHC design aperture.
CERN, Geneva
BNL, Upton, Long Island, New York
KEK, Ibaraki
Funding: This work was supported by the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395).
Modern colliders bring into collision a large number of bunches per pulse or per turn to achieve a high luminosity. The long-range beam-beam effects arising from parasitic encounters at such colliders are mitigated by introducing a crossing angle. Under these conditions, crab cavities (CC) can be used to restore effective head-on collisions and thereby to increase the geometric luminosity. In this paper, we discuss the beam dynamics issues of a single global crab cavity (GCC) for both nominal LHC optics and one upgrade LHC optics.
CERN, Geneva
BNL, Upton, Long Island, New York
KEK, Ibaraki
In 2008 beam successfully circulated in the LHC. Thanks to an excellent functioning of the BPM system and the related software, injection oscillations were recorded for the first 90 turns at all BPMs. The analysis of these data gives the unique opportunity of evaluating the periodic optics and inferring possible error sources.
CERN, Geneva
BNL, Upton, Long Island, New York
KEK, Ibaraki
For several years optics measurement and correction algorithms have been developed for the LHC. During 2008 these algorithms have been directly tested in the SPS and RHIC. The experimental results proving the readiness of the applications are presented.
CERN, Geneva
BNL, Upton, Long Island, New York
In early LHC commissioning, linear and "higher-order" polarity checks were performed for one octant per beam, by launching suitable free betatron oscillations and then inverting a magnet-circuit polarity or strength. Circuits tested included trim quadrupoles, skew quadrupoles, lattice sextupoles, sextupole spool-pieces, Landau octupoles, and skew sextupoles. A nonzero momentum offset was introduced to enhance the measurement quality. The low-intensity single-pass measurements proved sufficiently sensitive to verify the polarity and the amplitude of (almost) all circuits under investigation, as well as the alignment of individual trim quadrupoles. A systematic polarity inversion detected by this measurement helped to pin down the origin of observed dispersion errors. Later, the periodic "ring dispersion" was reconstructed from the full first-turn trajectory of an injected off-momentum beam, by removing, at each location, the large incoming dispersion mismatch, forward-propagated via the optics model. Various combinations of inverted trim quadrupoles were considered in this model until reaching a good agreement of reconstructed dispersion and prediction.
LAL, Orsay
CERN, Geneva
For luminosity and total cross section measurement, the standard LHC physics optics has been modified for the ATLAS experiment in the so-called high beta optics with a beta star of 2600m. The high beta optics takes into account the whole LHC ring. Protons are, then, tracked from the Interaction Point to the detectors. Tolerances on the beta star are given and the effect of misalignment errors is checked. We show the final High beta optics used and the impact of the misalignment effect on the measurement.
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.
Medium Energy eRHIC (MeRHIC), the first stage design of eRHIC, includes a multi-pass ERL that provides 4GeV high quality electron beam to collide with the ion beam of RHIC. It delivers a minimum luminosity of 1032 cm-2s-1. Beam-beam effects present one of major factors limiting the luminosity of colliders. In this paper, both beam-beam effects on the electron beam and the proton beam in MeRHIC are investigated. The beam-beam interaction can induce a head-tail type instability of the proton beam referred to as the kink instability. Thus, beam stability conditions should be established to avoid proton beam loss. Also, the electron beam transverse disruption by collisions has to be evaluated to ensure that the beam quality is good enough for the energy recovery pass. The relation of proton beam stability, electron disruption and consequential luminosity are carried out after thorough discussion.
BNL, Upton, Long Island, New York
Funding: Work performed under US DOE contract DE-AC02-98CH1-886
During the course of last RHIC runs the beta-functions at the collision points (beta*) have been reduced gradually to 0.7m. In order to maximize the collision luminosity and ensure the agreement of the actual machine optics with the design one, more precise measurements and control of beta* value and beta* waist location became necessary. The paper presents the results of the implementation of the technique applied in last two RHIC runs. The technique is based on well-known relation between the tune shift and the beta function and involves precise betatron tune measurements using BBQ system as well as specially developed knobs for beta* and beta* waist location control.
SLAC, Menlo Park, California
Funding: This work is supported by the Department of Energy contract DE-AC02-76SF00515.
FACET is a proposed facility at SLAC National Accelerator Laboratory for beam driven plasma wakefield acceleration research. It is proposed to be built in the SLAC linac sector 20, where it will be separated from the LCLS located downstream and will gain the maximum beam energy from the upstream two kilometers of linac. FACET will also include an upgrade to linac sector 10, where a new e+ compressor chicane will be installed. The sector 20 will require a new optics consisting of two chicanes for e+ and e- bunch length compression, a final focus system and an extraction line. The two chicanes will allow the transport of e- and e+ bunches together, their simultaneous compression and proper positioning of e+ bunch behind e- at the plasma Interaction Point (IP). For a minimal cost, the new optics will mostly use the existing SLAC magnets. The desired beam parameters at the IP are: up to 23 GeV beam energy, 2·1010 charge per bunch, 10 micron round beam spot without dispersion and 25 micron bunch length. Details of the FACET optics design and results of particle tracking simulations are presented.
ODU, Norfolk, Virginia
JLAB, Newport News, Virginia
Muons, Inc, Batavia
BNL, Upton, Long Island, New York
Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86351
Recirculating linear accelerators (RLA) are the most likely means to achieve the rapid acceleration of short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. One problem is that in the simplest schemes, a separate return arc is required for each passage of the muons through the linac. In the work described here, a novel arc optics based on a Non Scaling Fixed Field Alternating Gradient (NS-FFAG) lattice is developed, which would provide sufficient momentum acceptance to allow multiple passes (two or more consecutive energies) to be transported in one string of magnets. With these sorts of arcs and a single linac, a Recirculating Linear Accelerator (RLA) will have greater cost effectiveness and reduced losses from muon decay. We will develop the optics and technical requirements to allow the maximum number of passes by using an adjustable path length to accurately control the returned beam phase to synchronize with the RF.
JLAB, Newport News, Virginia
Muons, Inc, Batavia
Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86351
Neutrino Factories and Muon Colliders require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses International Linear Collider (ILC) RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness. We discus the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both μ+ and μ- species, with pulsed Linac quadrupoles to allow the maximum number of passes.
CLASSE, Ithaca, New York
Funding: Work supported by the National Science Foundation and the US Department of Energy
The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) for the investigation of the beam physics of a linear collider damping ring. The low beta interaction region optics have been replaced with simple FOFO lattice structures. Superconducting damping wigglers are located in straights where horizontal dispersion can be constrained to be zero to minimize horizontal emittance. The flexibility of the CESR optics allows for an energy reach of 1.5 GeV /beam→ 6.0GeV/beam and a wide range of emittances and radiation damping times. We exploit that flexibility for measurements of the dependencies of various phenomena, on energy, emittance, and damping rate. At 2GeV beam energy, with no damping wigglers, the minimum horizontal emittance is 10nm. With 16 meters of wiggler magnets operating at 1.9 T, the horizontal emittance is reduced by a factor of four to 2.5 nm and the radiation damping time to 56ms. With tuning and alignment we expect to reach a vertical emittance approaching that of the International Linear Collider (ILC) damping rings. We report on the details of the CesrTA optics and the measurements of optical parameters.
KEK, Ibaraki
The e+/e- injector LINAC in KEK usually successively injects into four rings, which are Low Energy Ring (LER) of KEKB (3.5GeV/e+), High Energy Ring (HER) of KEKB (8.0GeV/e-), Photon Factory (PF) (2.5GeV/e-) and Advanced Ring for pulse X-rays (PF-AR) (3.0GeV/e-). While LINAC continuously injects into LER and HER alternatively every about five minutes, keeping both of KEKB rings almost their full operating currents. It takes about one minute to switch beam mode of LINAC. PF and PF-AR are injected a few times in a day. Time for PF or PF-AR including mode-switch had taken about 20 minutes for each other. For PF injection, the switching time was shortened in 2005 and the occupancy time is about 5 minutes. In 2008, we succeeded to make the switching time shorter, 2 seconds for HER/LER, and Pulse-to-pulse alternatively injection for PF/HER using an event system. Especially for KEKB, the short switching time is contributed to provide high currents and to improve luminosity at which beam lives are too short to keep the high currents. In 2009, we have a plan to inject also for LER/HER pulse-to-pulse alternatively.
CERN, Geneva
BNL, Upton, Long Island, New York
EPFL, Lausanne
The grazing function g is introduced – a synchrobetatron optical quantity that parametrizes the rate of change of total angle with respect to synchrotron amplitude for particles grazing a collimator or aperture. The grazing function is particularly important for crystal collimators, which have limited acceptance angles. The implications for RHIC, SPS, Tevatron and LHC crystal implementations are discussed. An analytic approximation is derived for the maximum value of g in a matched FODO cell, and is shown to be in good agreement with a realistic numerical example. The grazing function scales linearly with FODO cell bend angle, but to is independent of FODO cell length.
CERN, Geneva
EPFL, Lausanne
IHEP Protvino, Protvino, Moscow Region
The UA9 experiment at the SPS aims at testing bent crystals for usage as collimators with high energy stored proton and heavy ion beams. The experiments will try to establish crystal-based cleaning efficiency with slowly diffusing beam halo. One method for evaluating efficiency relies on Roman Pots and is described elsewhere. An alternative method relies on observing the beam loss signals around the ring. Comparisons of losses escaping from standard collimators and bent crystals will allow determination of cleaning efficiency, equivalent to the definition used for the LHC collimation design. This alternative method is described and simulations with LHC collimation tracking tools for UA9 are discussed. The predicted beam losses along the SPS ring are presented for different orientations and amorphous layer thicknesses of the crystal. The effect of different diffusion speeds for the beam are discussed.
LBNL, Berkeley, California
Funding: US Department of Energy
Staging Laser Plasma Accelerators (LPA), which is necessary in order to substantially increase the electron beam energy, requires incoupling additional laser beams into accelerating stages. To preserve high accelerating gradient of LPA, it is imperative to minimize the distance that is needed for laser incoupling. Using a conventional mirror with PW-class lasers will require the incoupling distance to be as long as tens of meters due to limitations imposed by laser induced damage of the optic. In this presentation we will describe a new approach for the laser incoupling that is based on planar water jet plasma mirror. The plasma mirror can operate as close as few cm to the focus of the laser thus minimizing the coupling distance. Using a water jet instead of a solid target avoids mechanical scanning of the target surface as well as contamination of the vacuum by laser breakdown debris. Experimental results showing performance of the water jet plasma mirror will be presented and progress in staging experiments will be discussed
Fermilab, Batavia
The Synergia framework has been enhanced to include new Poisson solvers and new collective physics effects. Synergia now includes Sphyraena, a solver suite that provides the ability to handle elliptical beam pipes. Resistive wall effects, including intra- and inter-bunch effects in the presence of multiple bunches are also available. We present an overview of the updates in Synergia, focusing on these developments.
LANL, Los Alamos, New Mexico
At Los Alamos National Laboratory we are actively exploring the feasibility of constructing a 50-keV x-ray free-electron laser. For such a machine to be feasible, we need to limit the cost and size of the accelerator and, as this is intended as a user facility, we would prefer to use proven, conventional accelerator technology. Using recent developments in transverse-to-transverse and transverse-to-longitudinal emittance exchange optics *, **, we present a conceptual 20-GeV conventional electron accelerator design capable of producing an electron beam with a normalized transverse emittance as low as 0.2 mm-mrad, a root-mean-square (RMS) beam length of 74 fs, and an RMS energy spread of 0.01%. We also explore the possibility of introducing a crystallographic mask into the beam line. Combined with a transverse-to-longitudinal emittance exchange optic, we show that such a mask can be used to modulate the electron beam longitudinally to match the x-ray wavelength. This modulation, combined with the very low transverse beam emittance, allows us to not only generate 50-keV x-rays with a 20-GeV electron beam, but also drastically decrease the length of the required undulator.
*P. Emma, Z. Huang, K. -J. Kim, and P. Piot, Phys. Rev. ST Accel. Beams 9, 100702 (2006).
**B. E. Carlsten and K. A. Bishofberger, New J. Phys. 8, 286 (2006).
Fermilab, Batavia
Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Existing codes for accelerator design (e.g. MAD) are not well suited for ionization cooling channels where particles exhibit strongly dissipative and nonlinear motion. A system of Mathematica programs was developed which allows to: 1) find periodic orbit and eigenvectors of the transfer matrix around it with account of (regular part of) ionization losses and feeddown effect from nonlinear fields; 2) compute emittance growth due to scattering and straggling, find equilibrium values (if exist); 3) analyze nonlinear effects such as dependence of tunes and damping rates on the amplitudes, resonance excitation; 4) perform tracking with account of stochastic processes. Underlying theory and application to helical cooling channel are presented.
G.H. Gillespie Associates, Inc., Del Mar, California
A PARMILA 2 Module has been developed for the Particle Beam Optics Laboratory (PBO Lab). PARMILA 2 is a FORTRAN program used to both design and simulate radiofrequency ion linear accelerators. The program can be used to design radiofrequency accelerators that include drift tube linac (DTL) structures, coupled cavity linac (CCL) structures, coupled-cavity drift tube linac (CC-DTL) structures, and superconducting accelerator structures. PARMILA 2 can also be used to simulate beams in these structures and in transport lines that with magnetic, radiofrequency and electrostatic beam optics elements. PBO Lab provides a sophisticated graphic user interface (GUI) for multiple optics codes. From the same familiar interface users can run TRANSPORT, TURTLE, MARYLIE, TRACE 3-D and DECAY-TURTLE. PARMILA 2 now joins this suite of optics codes available as PBO Lab Modules. New PBO Lab tools have been developed to assist users in utilizing different optics codes to simulate and validate the performance of an accelerator designed with PARMILA 2. An overview of the new PARMILA 2 module and associated new tools is presented and some of the GUI features are illustrated.
CLASSE, Ithaca, New York
KEK, Ibaraki
Funding: NSF
Engineering data sets were collected with the CESRTA x-ray beam size monitor (xBSM) during November 2008 and January 2009 runs. We report on the performance of the InGaAs photodiode array detector, including time response and signal-to-noise. We report on the observed measurement resolution for changes in the damping ring vertical beam size using the interchangeable optics elements: slits, coded apertures, and a Fresnel zone plates. Observed resolutions are compared to predictions based on characteristics of the optics elements.
CERN, Geneva
Until now, the continuous monitoring of the LHC lattice has been considered as impractical due to tight constraints on the maximum allowed beam excitations and acquisition time usually required for betatron function measurements. As an further exploitation of the Base-Band-Tune (BBQ) detection principle, already widely used for tune diagnostic, a real-time beta-beat measurement prototype has been successfully tested at the CERN SPS based on the continuous measurement of the cell-to-cell betatron phase advance. Tests show that the phase resolutions is better than a degree corresponding to a peak-to-peak beta-beat resolution of about one percent. Due to the system's high sensitivity it required only micro-metre range excitation, making it compatible with nominal LHC operation. This contribution discusses results, measurement systematics and possible additional exploitation that may be used to improve the nominal LHC performance.
Fermilab, Batavia
ANL, Argonne
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The challenge of mitigating the strong enhancements of the optical transition radiation (OTR) signal observed after bunch compression in the Advanced Photon Source (APS) linac chicane and at the Linac Coherent Light Source (LCLS) has recently been addressed. We have demonstrated a technique to mitigate the intensity of the coherent OTR (COTR) relative to the OTR signals on the APS beams at 325 MeV. Since the previously reported spectral content of the COTR at LCLS after the first compression stage is similar, the concepts should also apply to LCLS. We utilized the stronger violet content at 400 nm of the OTR compared to the observed gain factors of the COTR in the blue to NIR regime. We also demonstrated the use of an LSO:Ce scintillator that emits violet light to support lower-charge imaging. Spectral-dependence measurements of the COTR were done initially at the 325-MeV station using a series of band pass filters inserted before the CCD camera, but recent tests with an Oriel spectrometer with ICCD readout have extended those studies and confirmed the concepts. These techniques are complementary to the proposed use of a laser heater to mitigate the microbunching itself at LCLS.
KEK, Ibaraki
CLASSE, Ithaca, New York
UH, Honolulu, HI
Funding: Work supported in part by the US-Japan Cooperation Program
We are working on the development of a high-speed x-ray beam profile monitor for high-resolution and fast response for beam profile measurements to be used at CesrTA and SuperKEKB*. The optics for the monitor are based on a technique borrowed from x-ray astronomy, coded-aperture imaging, which should permit broad-spectrum, low-distortion measurements to maximize the observable photon flux per bunch. Coupled with a high-speed digitizer system, the goal is to make turn-by-turn, bunch-by-bunch beam profile measurements. Following initial tests with a low-resolution mask at large beam sizes (vertical size ~200 um), a high-resolution mask has been made for use with low-emittance beams (vertical size ~10 um) at CesrTA. The first performance results of the high-resolution mask on the low-emittance CesrTA beam are presented.
*J.W. Flanagan et al., Proc. EPAC08, Genoa, {10}29 (2008).
NHMFL, Tallahassee, Florida
Muons, Inc, Batavia
Magnetic confinement fusion reactors (tokamaks) require the development of magnets capable of generating large fields under stringent structural constraints. High temperature superconducting magnets which are well suited to this application are however vulnerable to quench occurrence during operation. Temperature and strain sensors based on fiber optics are being developed as a countermeasure to this contingency. Optical fibers with Bragg gratings are amenable to embedding within superconducting magnets to monitor temperature, strain, irradiation, and to detect quench occurrence. In a length of YBCO tape where quench propagation velocities are slow, we show that it is possible to detect the event occurrence using fiber optic sensors even with a sampling rate as low as 1 Hz. This preliminary result demonstrates the feasibility of using fiber optic sensors to monitor the temperature and strain condition along the length within a coil. These sensors could be used to provide feedback to or trigger magnet protection systems. This would be an invaluable method for mitigating damage to superconducting magnets and increasing up-time for reactors.
ANL, Argonne
Funding: This work was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CHlI357.
During an operating period in which a sextupole unknowingly connected with the wrong polarity resulted in reduced beam lifetime, a list of machine physics experiments and simulations were developed to identify possible gradient errors of one or more sextupole magnets. We tried tune dependence on orbit, response matrix measurements at different momenta, sector-wise chromaticity measurements, empirical search with sextupole harmonics, and guidance from tracking simulations. The practicality of each will be discussed.
ANL, Argonne
Northern Illinois University, DeKalb, Illinois
An exotic beam facility for the production of rare isotopes such as the Facility for Rare Isotope Beams (FRIB) at Michigan State University will require a high resolution fragment separator to separate isotopes of varying mass and charge. The goal of the fragment separator is to produce a high-purity beam of one rare isotope. Sources of contamination in a beam such as this are isotopes with a similar magnetic rigidity to the separated isotope and those which are produced by fragmentation in the energy degrader. This can be particularly detrimental when a contaminating isotope has a large cross section. Here we investigate beam purity as a function of the separated isotope and the type of fragment separator setup used, i.e. one stage, two stage, or one stage with gas cell branch.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An energy recovery linac (ERL) is one of the candidates for an upgrade of the Advanced Photon Source (APS). In addition to the APS ring and full-energy linac, our design also includes a large turn-around arc that could accommodate new x-ray beamlines as well. In total, the beam trajectory length would be close to 3 km. The ERL lattice has strong focusing to limit emittance growth, and it includes strong sextupoles to keep beam energy spread under control and minimize beam losses. As in storage rings, trajectory errors in sextupoles will result in lattice perturbations that would affect delivered x-ray beam properties. In storage rings, the response matrix fit method is widely used to measure and correct linear lattice errors. Here, we explore the application of the method to the linear lattice correction and coupling correction of an ERL.
LNLS, Campinas
The synchrotron machine at the Brazilian Synchrotron Light Laboratory (LNLS) is a storage ring for 1.37 GeV electrons composed of six DBA cells whose lengths add up to around 93 meters of circumference. There are 18 horizontal and 24 vertical correctors available in the ring for correcting the orbit as measured at 24 BPMs. In the past, stored beams have been delivered which successfully fulfilled user’s stability and emittance demands. This has been accomplished by fine tuning the machine using mostly measured beam parameters. The ongoing commissioning of the a new undulator beamline, which is expected to become the most demanding one, puts pressure in the direction of improving existing models of the ring optics in order to envisage ways of improving beam quality. In this paper we discuss preliminary tests with LOCO* at the LNLS. We report on the impact of the calibration of the machine based on LOCO calculations through the analysis of standard experiments and optics parameters such as beta-beat reduction, improvement of life-time and so on.
*LOCO in the Beam Dynamics Newsletter, 44, ICFA, December 2007.
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.
The Booster to AGS (BtA) transfer line was designed to match both ions and protons into the AGS lattice. For proton beam operation the only constraint on the optics is to define a match to the AGS lattice. For ions operation there are constraints introduced by a stripping foil in the upstream part of the transfer line. For polarized proton operation there is the complication that the lattice to match into in the AGS is distorted by the presence of two partial snake magnets. In the 2008 polarized proton run it was observed that there was an optical injection mismatch. Beam experiments were conducted that showed disagreement with the model. In addition, these studies revealed some minor problems with the instrumentation in the line. A new model and more reliable measurements of the transfer line magnet currents have been implemented. Another series of experiments were conducted to test these modifications and to collect a more complete set of data to allow better understanding of the beam dynamics during the transfer and better understanding of the instrumentation. In this paper we will present the results of these experiments and comparison to the new model of the BtA.
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.
As part of the efforts to increase polarization and luminosity in RHIC during polarized proton operations we have modified the injection optics and stripping foil geometry in the AGS Booster in order to reduce the emittance growth during H- injection. In this paper we describe the modifications, the injection process, and present results from beam experiments.
BNL, Upton, Long Island, New York
Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886
In this paper, we discuss an algorithm for constructing a numerical linear optics model for dipole magnets from a 3D field map. The difference between the numerical model and K. Brown’s analytic approach is investigated and clarified. It was found that the optics distortion due to the dipoles’ fringe focusing must be properly taken into account to accurately determine the chromaticities. In NSLS-II, there are normal dipoles with 35-mm gap and dipoles for infrared sources with 90-mm gap. This linear model of the dipole magnets is applied to the NSLS-II lattice design to match optics parameters between the DBA cells having dipoles with different gaps.
CAEP/IFP, Mainyang, Sichuan
The capability of the chromatic correction of Zumbro Lens lies on the angle-position correlation, which is obtained by passing the beam through an expander or quadruples. However even after a long distance drift downstream the expander, the angle-position correlation can not be perfect because of the existence of finite emittance. This paper discusses the influence of the emittance to the chromatic correction and the optimization of beam status in phase space at the entrance of the expander.
IHEP Beijing, Beijing
JAI, Egham, Surrey
KEK, Ibaraki
ICEPP, Tokyo
SLAC, Menlo Park, California
University of Tokyo, Tokyo
Funding: NSFC 10525525 and 10775154. CNRS-IN2P3 and ANR.
The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. We report on techniques developed based on simulation studies to adjust the horizontal and vertical beam waists independently in the presence of errors, at two different IP locations where the beam size can be measured with different accuracies. During initial commissioning, we will start with larger than nominal β-functions at the IP, to reduce the effects from higher-order optical aberrations and thereby simplify the optical corrections needed. The first measurements in such intermediate β-configurations are reported.
DESY, Hamburg
The post-linac collimation system should simultaneously fulfil several different functions. In first place, during routine operations, it should remove with high efficiency off-momentum and large amplitude halo particles, which could be lost inside undulator modules and become source of radiation-induced demagnetization of the undulator permanent magnets. The system also must protect the undulator modules and other downstream equipment against mis-steered and off-energy beams in the case of machine failure without being destroyed in the process. From beam dynamics point of view, the collimation section should be able to accept bunches with different energies (up to ± 1.5% from nominal energy) and transport them without deterioration not only of transverse, but also of longitudinal beam parameters. In this article we present the optics solution for the post-linac collimation system which fulfils all listed above requirements.
DESY, Hamburg
The aim of the FLASH facility linac is to create electron bunches of small transverse emittance and high current for the FLASH free-electron laser at DESY. Available operational experience indicates that in order to optimize SASE signal at different wavelengths or to fine-tune the FEL wavelength, empirical adjustment of the machine parameters is required and, therefore, the sensitivity of the beamline to small changes in the beam energy and in the magnet settings becomes one of the important issues which affects the final performance. In this article the transverse optics of the FLASH beamline with low sensitivity to changes in beam energy and quadrupole settings is presented. This optics is in operation since spring 2006 and has shown a superior performance with respect to the previous setup of the transverse focusing.
Diamond, Oxfordshire
JAI, Oxford
A proposal has been developed to modify a long insertion straight (~11.4 m long) of the DIAMOND storage ring. Additional quadrupoles provide two sections with small vertical beta-function values, in order to accommodate two canted in-vacuum undulators for the imaging and coherence branches of the I13 beam line. A further requirement was to provide a horizontal focussing of the emitted undulator radiation by means of a positive alpha-x in the second section. This optic is obtained using a small relaxation in the “pitrick”, approximately preserving the on-momentum nonlinear dynamics of the ring. The effects of the optic on beam dynamics (i.e. beam lifetime, injection etc.) and possible compensation schemes are presented.
CERN, Geneva
The maximum intensity the CERN PS has to deliver is continuously increasing. In particular, during the next years, one of the most intense beam ever produced in the PS, with up to 3000·1010 proton per pulse, should be delivered on a regular basis for the CNGS physics program. It is now known that the existing radiation shielding of the PS in some places is too weak and constitutes a major limitation due to large beam losses in specific locations of the machine. This is the case for the injection region: losses appear on the injection septum when the beam is injected in the ring and during the first turn, due also to an optical mismatch between the injection line and the PS. This paper presents the experimental studies and the simulations which have been made to understand the loss pattern in the injection region. Possible solutions to reduce the beam losses will be described, including the computation of a new injection optics.
CERN, Geneva
As for the final focus systems of linear colliders, the chromatic aberrations induced by low-beta insertions can seriously limit the performance of circular colliders. The impact is two-fold: (1) a substantial off-momentum beta-beating wave travelling all around of the ring leading to a net reduction of the mechanical aperture of the low-beta quadrupoles but also impacting on the hierarchy of the collimator and protection devices of the machine, (2) a huge non-linear chromaticity, essentially Q’’ and Q’’’, which, when combined with the geometric non-linear imperfection of the machine could substantially reduce the momentum acceptance of the ring by sending slightly off-momentum particles towards non-linear resonances. These effects will be analyzed and illustrated in the framework of the LHC insertions upgrade and a strategy for correction will be developed, requiring a deep modification of the LHC overall optics.
CERN, Geneva
The 3 km long TI 8 transfer line is used to transfer 450 GeV proton and ion beams from the SPS to LHC collider. As part of a detailed optics investigation program the chromaticity of the transfer line was measured. Kick response data of the transfer line was recorded for various extraction energy offsets in the SPS. The quadrupolar and sextupolar field errors over the whole transfer line dipoles, a systematic error of the main quadrupole strengths and the initial momentum error were estimated by a fit. Using the updated model, the chromaticity of the line was then calculated.
CERN, Geneva
Fermilab, Batavia
Funding: Work partly supported by Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Through May to September 2008, further beam commissioning of the SPS to LHC transfer lines was performed. For the first time, optics and dispersion measurements were also taken in the last part of the lines, and into the LHC. Extensive trajectory and optics studies were conducted, in parallel with hardware checks. In particular dispersion measurements and their comparison with the beam line model were analysed in detail and led to propose the addition of a “dispersion-free” steering algorithm in the existing trajectory correction program.
CERN, Geneva
The LHC phase II collimation project requires beam shock and impact tests of materials used for beam intercepting devices. Similar tests are also of great interest for other accelerator components such as beam entrance/exit windows and protection devices. For this purpose a dedicated High Radiation Material test facility (HiRadMat) is under study. This facility may be installed at CERN at the location of a former beam line. This paper describes the associated beam line which is foreseen to deliver a 450 GeV proton beam from SPS with an intensity of up to 3·1013 protons per shot. Different beam line designs will be compared and the choice of the beam steering and diagnostic elements will be discussed, as well as operational issues.
CERN, Geneva
BNL, Upton, Long Island, New York
The effect of magnet misalignments in the beam orbit and linear optics functions are reviewed and correction schemes are applied to the negative momentum compaction lattices of PS2. Chromaticity correction schemes are also proposed and tested with respect to off-momentum optics properties. The impact of the correction schemes in the dynamic aperture of the different lattices is finally evaluated.
CERN, Geneva
BNL, Upton, Long Island, New York
In view of the CERN Proton Synchrotron proposed replacement with a new ring (PS2), a detailed optics design as been undertaken following the evaluation of several lattice options. The basic arc module consists of cells providing negative momentum compaction. The straight section is formed with a combination of FODO and quadrupole triplet cells, to accommodate the injection and extraction systems, in particular the H- injection elements. The arc is matched to the straight section with a dispersion suppressor and matching module. Different lattices are compared with respect to their linear optics functions, tuning flexibility and geometrical acceptance properties.
Fermilab, Batavia
Funding: Work supported by Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Recent advances in the HTS magnet technology and ionization cooling theory have re-launched the interest of the physics community in the realization of a high energy, high luminosity Muon Collider (MC). The large muon energy spread requires large momentum acceptance and the required luminosity calls for beta* in the mm range. To avoid luminosity degradation due to the hour-glass effect, the bunch length must be comparatively small. To keep the needed RF voltage inside feasible limits the momentum compaction factor must be as small as possible. Under these circumstances chromatic effects correction, energy acceptance, dynamic aperture and longitudinal motion stability are main issues of a MC design. In this paper we give an overview of various lattice designs toward a high luminosity, large energy acceptance MC currently under study at Fermilab.
GSI, Darmstadt
The GSI heavy ion synchrotron SIS18 will be used as a booster for the SIS100 synchrotron of the new FAIR facility. The linear corrections and measurements are a necessary step before the nonlinear field errors can be applied. A tune response to a change in a sextupole magnet strength for a certain Closed Orbit (CO) deformation is used to verify beta-functions of the SIS18 model at the location of the ring's sextupoles for chromaticity correction. The progress in development of Nonlinear Tune Response Matrix (NTRM) technique to diagnose nonlinear field components is presented.
Imperial College of Science and Technology, Department of Physics, London
The Race Track design for the Decay Ring of a Neutrino Factory is studied with the MAD-X code. Optimisation of the working point, study of resonances and of dynamic aperture for several off-momentum cases are presented. An introduction to the problem of beam losses is given.
Imperial College of Science and Technology, Department of Physics, London
The Muon Ionisation Cooling Experiment (MICE) at RAL will be the first apparatus to study muon cooling at high precision. Muons are produced along a transport beamline in a super-conducting solenoid via pion decay. The final beam emittance is generated by tuning the quadrupoles for beam size matching. The beam angular divergence is matched in a variable-thickness diffuser, which is a re-entrant mechanism inside the first solenoid, automatically changeable in few minutes from 0 to 4X0. The initial normalized emittance of the beam (few mm rad) will be inflated up to 10 mm rad in order to cover the (eN,P) matrix required by the experiment. Details of beamline tuning are presented.
IUCF, Bloomington, Indiana
ORNL, Oak Ridge, Tennessee
Funding: Division of Materials Science, U.S. Department of Energy, under contract number DE-AC05-96OR22464 with UT-Battelle Corporation for Oak Ridge National Laboratory
In order to achieve a more robust and optimal performance, the difference between the real machine and its underlying model should be understood and eliminated. Discrepancies between the measuremed and predicted linear optics suggest possible errors of the focusing magnets and diagnostic devices. To find and correct those errors, a widely used method, orbit response matrix (ORM)* approach is applied to the SNS storage ring, which successfully brings the tune deviation from 3% to 0.1%, improves horizontal beta beating from 15% to 3%, and perfectly flattens the orbit. In this article, we discussed the progress and possible future improvements with the SNS ring optics correction.
*J. Safranek, "Experimental determination of storage ring optics using closed orbit response measurements", Nucl. Inst. and Meth. A388, (1997), pg. 27
BNL, Upton, Long Island, New York
Funding: Department of Energy
Precise measurements of optics from coherent betatron oscillations driven by ac dipoles have been demonstrated at RHIC and the Tevatron. For RHIC, the observed rms beta-beat is about 10%. Reduction of beta-beating is an essential component of performance optimization at high energy colliders. A scheme of optics correction was developed and tested in the RHIC 2008 run, using ac dipole optics for measurement and a few adjustable trim quadrupoles for correction. In this scheme, we first calculate the phase response matrix from the measured phase advance, and then apply a singular value decomposition (SVD) algorithm to the phase response matrix to find correction quadrupole strengths. We present both simulation and some preliminary experimental results of this correction.
CERN, Geneva
SOLEIL, Gif-sur-Yvette
The successful correction of non-linear resonances in DIAMOND using the BPM turn-by-turn data has motivated testing this approach in SOLEIL in collaboration with CERN. We report on the first experiences towards the correction of non-linear resonances in SOLEIL.
G.H. Gillespie Associates, Inc., Del Mar, California
STAAR/AWR Corporation, Mequon
Funding: Work at G. H. Gillespie Associates, Inc. funded by the U.S. Department of Energy SBIR grant number DE-FG02-05ER84360
An automated procedure for the calculation of particle transfer maps using computed magnetic field data has been developed for several types of magnetic quadrupoles. The Automated Transfer Map Generator (ATMG) software used for these calculations combines the Analyst program and specialized modules of the Particle Beam Optics Laboratory (PBO Lab). Analyst's scripted solids capability is used to develop models of different magnet concepts. The geometry and material attributes for a given magnet concept are encapsulated by a small number of magnet parameters. Quadrupoles of the same basic concept can be simulated by using different values for the magnet parameters. The three-dimensional magnetic field solver (MS3p) of the Analyst program is used to obtain the fields. New PBO Lab modules are used to automate the field computation, and then calculate the transfer maps and matrices through third-order using the Venturini-Dragt method. Examples for three different types of magnetic quadrupole lenses are presented: electromagnetic air-core, electromagnetic iron-core, and rare-earth permanent magnet quadrupoles.
KEK, Ibaraki
The value calculated by using general-purpose computer code SAD for the accelerator is sometimes different from actual measurements. This is because many kinds of factor cause error, like machine error, so we can’t include such error exactly in SAD. Therefore, on the contrary, we consider the model which includes error by using measurement data and derive Hamiltonian from it.
SLAC, Menlo Park, California
Funding: Work supported by the US Department of Energy, Office of Basic Energy Sciences.
We present nonlinear dynamics measurements and tracking for the SPEAR3 storage ring. SPEAR3 does not have a vertical pinger magnet, so we have developed a method of measuring (x, y) frequency maps by exciting vertical oscillations using a strip line driven with a swept frequency. When the vertical oscillations reach the desired amplitude, the drive is cut, and an injection kicker excites horizontal oscillations. The subsequent free horizontal and vertical betatron oscillations are digitized turn-by-turn. We have used measured and tracked frequency maps in (x, y) and (x, energy) to characterize and optimize the dynamic aperture, injection and lifetime of the SPEAR3 low emittance optics.
SLAC, Menlo Park, California
Life Imaging Technology, Palo Alto, California
Funding: Work sponsored by U.S. Department of Energy Contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
An intensified, fast-gated CCD camera was recently installed on the visible diagnostic beam line in SPEAR3. The ~2nS electronic gate capability, ability to make multiple-exposure images and to acquire sequences of images provides good diagnostic potential. Furthermore, the addition of a rotating mirror just upstream of the photocathode provides the ability to optically ‘streak’ multiple images across the photocathode. In this paper, we report on several fast-gated camera studies including (1) resonant excitation of vertical bunch motion, (2) imaging of the injected beam with and without emittance-spoiling windows in the upstream transfer line, (3) injection kicker tuning to minimize perturbations to the stored beam and (4) images of short-bunch ‘bursting’ in the low momentum-compaction mode of operation.
USTC/NSRL, Hefei, Anhui
In HLS streak camera system has been built. The system is used to measure some parameters of bunch like bunch length, longitudinal bunch profile and synchrotron frequency and so on, as it may report a direct derivation of fundamental machine characteristics. The system mainly consists of the synchrotron light extracting optics setup, the OPTOSCOPE streak camera and PC with a frame grabber interface card. The light extracting optics setup is used to extract synchrotron light at the bending magnet and the setup consists of the light extracting path and the optics imaging system. The streak camera realizes the functions of acquiring light and imaging. PC with a frame grabber interface card and ARP-Optoscope software package is used to monitor the light in real-time, acquire the image of light and analyze the data. The streak camera system operates with either synchroscan sweep mode or dual time base sweep mode. At present, some results are given, which include the bunch lengthening, the longitudinal bunch profile and the synchrotron frequency. These results are compared with the results acquired by using oscilloscope.
University of Tokyo, Tokyo
KEK, Ibaraki
ICEPP, Tokyo
Commissioning of the ATF/ATF2 project will start in the winter of 2008 to 2009, with the aim of studying beam optics, diagnostic instrumentations, and tuning processes for around 35 nm beam size. The project is the realistic scaled down model of the ILC final focus system, and also, studies in the project offered important findings for future accelerator physics. In this presentation, we will present about the status of the first commissioning of the Shintake monitor for ATF2. The monitor is located at the virtual interaction point of the ATF2 (the focus point) to measure beam size. A measurable ranges as a design are from 6 micron down to 20 nm in vertical and down to several microns in horizontal. That wide range allows us to used the detector from the beginning of the beam tuning process. The monitor scheme was originally proposed by T. Shintake and verified using around 60 nm beam at FFTB project. We upgraded the detector system for ATF2 of smaller beam size and implemented a laser wire scheme for horizontal beam size measurement. These additional capabilities are also presented.
SLAC, Menlo Park, California
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
JAI, Oxford
KEK, Ibaraki
IHEP Beijing, Beijing
LAL, Orsay
Royal Holloway, University of London, Surrey
IN2P3-LAPP, Annecy-le-Vieux
OXFORDphysics, Oxford, Oxon
ATOMKI, Debrecen
CERN, Geneva
DESY, Hamburg
Fermilab, Batavia
Kyungpook National University, Daegu
PAL, Pohang, Kyungbuk
Kyoto ICR, Uji, Kyoto
ICEPP, Tokyo
University of Tokyo, Tokyo
UCL, London
BNL, Upton, Long Island, New York
Tohoku University, Graduate School of Science, Sendai
UMAN, Manchester
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
Cockcroft Institute, Warrington, Cheshire
ATF2 is a final-focus test beam line that attempts to focus the low-emittance beam from the ATF damping ring to a beam size of about 37 nm, and at the same time to demonstrate nm beam stability, using numerous advanced beam diagnostics and feedback tools. The construction is well advanced and beam commissioning of ATF2 has started in the second half of 2008. ATF2 is constructed and commissioned by ATF international collaborations with strong US, Asian and European participation.
CERN, Geneva
The aim of the last CLIC test facility CTF3, built at CERN by an international collaboration, is to prove the main feasibility issues of the CLIC two-beam acceleration technology. The main points which CTF3 should demonstrate by 2010 are the generation of a very high current drive beam and its use to efficiently produce and transfer RF power to high-gradient accelerating structures. To prove the first point a delay loop and a combiner ring have been built, following a linac, in order to multiply the current by a factor two and four, respectively. The power generation and transfer and the high gradient acceleration are instead demonstrated in the CLIC experimental area (CLEX), where the drive beam is decelerated in special power extraction structures(PETS). In this paper we describe the results of the combination in the ring, properly working after the cure of the vertical instability which limited high current operation, and the commissioning of the new beam lines installed in the second half of 2008, including response matrix analysis and dispersion measurements used to validate the optics model. The results of the energy transfer will be also briefly described.
KEK, Ibaraki
The University of Liverpool, Liverpool
SLAC, Menlo Park, California
One of the goals of the Accelerator Test Facility (ATF) at KEK is to demonstrate ultra-low vertical emittance for linear colliders. Highly precise correction of the vertical dispersion and betatron coupling will be needed to achieve the target of 2 pm (which will be required for ILC). Optics correction and tuning must be supported by an accurate model, which can be developed from a variety of beam measurements, including orbit response to dipole kicks, beta functions at the quadrupoles, etc. Here, we report experimental data and the status of the model and low-emittance tuning.
LAL, Orsay
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: CNRS-IN2P3, ANR
The purpose of ATF2 is to deliver a beam with stable very small spotsizes as required for future linear colliders such as ILC or CLIC. To achieve that, precise controls of aberrations such as dispersion and coupling are necessary. Initially, coupling correction upstream of the final focus line of the ATF2 will be performed with only two skew quadrupoles (SQ) in the extraction line (EXT). We thus first examine the feasability of coupling correction in the EXT with those two SQ, considering several possible coupling error sources. The correction is first based on an algorithm of minimisation of vertical emittance with successive skew scans, implemented in the Flight Simulator code*. We will then investigate new methods to measure and extract the first order four coupling parameters of the beam matrix in order to perform a more direct and accurate coupling correction.
*G. White et al., "A flight simulator for ATF2…", TUPP016 EPAC08
LBNL, Berkeley, California
Analytical formula of the 6X6 transfer matrix of a magnetic solenoid is derived. As an example, analytical and numerical study of a bunch compressor consists of such solenoids is presented.
SLAC, Menlo Park, California
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
KEK, Ibaraki
LAL, Orsay
UMAN, Manchester
CERN, Geneva
Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515
Using a new extraction line currently being commissioned, the ATF2 experiment plans to test a novel compact final focus optics design using a local chromaticity correction scheme, such as could be used in future linear colliders*. Using a 1.3 GeV beam of ~30nm normalised vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical IP waist of 35nm. We discuss our planned strategy, implementation details and early experimental results for tuning the ATF2 beam to meet the primary goal. These optics require uniquely tight tolerances on some magnet strengths and positions, we discuss efforts to re-match the optics to meet these requirements using high-precision measurements of key magnet elements. We simulated in detail the tuning procedure using several algorithms and different code implementations for comparison from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within 10% of the design optics value in at least 90% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks.
*"ATF2 Proposal", ATF2 Collaboration (Boris Ivanovich Grishanov et al.)., KEK-REPORT-2005-2, Aug 23, 2005.
SLAC, Menlo Park, California
BNL, Upton, Long Island, New York
Funding: US DOE
Unlike an electron storage ring with radiation damping, resonance excitation is unsuitable to a proton storage ring for turn-by-turn betatron orbit data. However, one may consider modified betatron motion driven by ac dipoles oscillating at frequencies near the betatron tunes. With a matrix formulation for adding ac-dipole effects on 2-D coupled one-turn map, we concatenate the ac-dipole effects and the one-turn map to obtain a modified linear map. The ac-dipole effects are equivalent to inserted symplectic linear maps at the ac-dipole locations. If the maps are normalized through decoupling similarity transformation, the decoupled maps for the ac-dipole effects are equivalent to 1-D thin quads inserted at the corresponding locations, the same conclusion for the 1-D driven oscillation*. For optics modeling with MIA technique**, one must make sure that there are, simultaneously, two transverse ac-dipole driven betatron oscillations along with one longitudinal synchrotron oscillation. Once the optics model for the modified betatron motion is obtained, one can then obtain the proton storage ring model by de-concatenating the inserted ac-dipole linear maps.
* R. Miyamoto, S.E. Kopp, A. Jansson, and M.J. Syphers, PRSTAB 11, 084002 (2008).
** Y.T. Yan, ICFA Beam Dynamics Newsletter, No. 42, pp. 71-87 ( 2007), Y. Cai, W. Chou, Eds.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
A scaling fixed field alternating gradient (FFAG) accelerator provides large momentum acceptance despite of constant field in time. Optical functions are nearly the same for large momentum range. We have designed a straight beam transport (BT) line using a scaling FFAG type magnet which has a field profile of x^k, where x is the horizontal coordinate and k is the field index. This BT line has very large momentum acceptance as well, for example ±50%, and optical functions do not practically depends on momentum. We also designed a dispersion suppressor at the end by the combination of a unit cell with different field index k so that the momentum dependence of orbits should be eliminated at the exit. An obvious application of this design is the BT line between FFAG accelerator and gantry of a particle therapy facility. However, we also consider it for the transport of muon beams, which have large emittance and momentum spread. This could be an alternative to the conventional BT line with solenoid or quadrupole because of the strong focusing nature of quarupole and the large momentum acceptance like solenoid.
SSRF, Shanghai
Funding: SSRF
The ssrf is a 3rd generation light source under commissioning. The commissioning of the storage ring has progressed very well so far. The periodicity and symmetry of the linear optics in a real storage ring is important, however maybe be broken by various errors, such as field errors, manufactured errors. A distorted linear optics can excite stronger nonlinear resonances, which will reduce the storage ring dynamic aperture and make the storage ring suffer from low injection efficiency and short beam lifetime. Therefore, it is necessary to restore the designed periodicity or symmetry of the linear optics based on measured closed orbit distortion. The calibration procedure can be done by using LOCO (the Linear Optics from Closed Orbit). After fitting the measured response matrix by the model one, the linear optics of the storage ring is calibrated. And different operation modes have been also measured and calibrated.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
The specified vertical emittance for the ILC damping rings is 2 pm. A major objective for the Accelerator Test Facility (ATF) at KEK is to demonstrate reliable operation in this low emittance regime. LOCO is a tool for identifying optics errors in storage rings, based on fitting a lattice model to the measured closed orbit response matrix. This technique can be used to determine corrections to minimise vertical dispersion and betatron coupling, and hence reduce the vertical emittance. So far, efforts to apply LOCO to the ATF to achieve 2 pm vertical emittance have met with limited success. This paper presents the results of simulations aiming to identify possible limitations in the technique. We consider the effects of varying parameters controlling the fit of the lattice model to the measured data, and investigate possible degeneracies (e.g. between skew quadrupole strengths and tilts of the corrector magnets) that may limit the quality of the correction achievable using this technique.
BNL, Upton, Long Island, New York
CERN, Geneva
Funding: This work has been partially performed under the auspices of US department of energy
Measurements of transverse impedance in the SPS to track the evolution over the last few years show discrepancies compared to the analytical estimates of the major contributors. Recent measurements to localize the major sources of the transverse impedance using intensity dependent optics are presented. Some simulations using HEADTAIL to understand the limitations of the reconstruction and related numerical aspects are also discussed.
BNL, Upton, Long Island, New York
NSCL, East Lansing, Michigan
CERN, Geneva
Studies of space charge effects in the Small Isochronous Ring (SIR) at Michigan State University revealed a fast longitudinal instability at and below the transition that could not be explained by the conventional negative mass instability. The observed beam behavior can be explained by the effect of the radial component of the coherent space charge force on the longitudinal motion. The transverse coherent space charge force effectively modifies the slip factor shifting the isochronous point and enhancing the negative mass instability. This paper presents results of numerical and experimental studies of the longitudinal beam dynamics in SIR and proposes an analytical model explaining the results.
JAI, Oxford
Diamond, Oxfordshire
Diamond is a third generation synchrotron light source built to generate infra-red, ultraviolet and X-ray synchrotron radiation (SR) of exceptional brightness. The operation of the Diamond storage ring with short electron bunches for generation of Coherent THz radiation and short X-ray pulses for time-resolved experiments is limited by the onset of microbunch instabilities. We have started a project to investigate the longitudinal electron beam dynamics and microbunch instabilities in the Diamond storage ring. In the first experiment we used an ultra-fast (time response is about 250 ps) Schottky Barrier Diode sensitive to the radiation within the 3.33-5 mm wavelength range. When the single bunch current exceeded 1.9 mA we observed a set of sub-THz bursts appearing quasi-periodically while the beam was circulating in the ring. The fast response allowed us to detect the signal turn-by-turn, which gives us an opportunity to study the bursts’ structure and evolution. It also allows us to study the effect in a multi-bunch mode when bunches are only 2 ns apart. In this report we will present our first preliminary results and also discuss future plans.
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.
An online modeling system is being developed for the RHIC injector complex, which consists of the Booster, the AGS and the transfer lines connecting the Booster to the AGS and the AGS to RHIC. Historically the injectors have been operated using static values from design specifications or offline model runs, but tighter beam optics constraints required by polarized proton running (e.g. accelerating with near-integer tunes) have necessitated a more dynamic system. An online model server for the AGS has been implemented using MAD-X as the model engine, with plans to extend the system to the Booster and the injector transfer lines and to add the option of calculating optics using the Polymorphic Tracking Code (PTC) as the model engine.
BNL, Upton, Long Island, New York
Funding: Work performed under auspices of the U.S. Department of Energy under Contract No. DE-AC02-98CH10886 with Brookhaven Science Associates, LLC.
A distributed software architecture for high level applications is under development at the NSLS-II (National Synchrotron Light Source II) project. One of the important issues is to make accelerator simulation model run on a standalone model server. To enhance the capacity of the model server, it is required to have a set of narrow and general API to accommodate various existing tracking codes. A preliminary study for the API development has been started at NSLS-II based on The MMLT (Matlab Middle Layer Toolkit).A new interface is developed for the MMLT to support another simulation engine known as Tracy. A virtual accelerator is also built for the NSLS-II storage ring based on the Tracy code and the EPICS framework. Although we don't have a real machine, we can evaluate and develop our high leval application with the support of virtual accelerator. This paper describes the current status of the software architecture for high level applications.
SLAC, Menlo Park, California
Funding: Department of Energy contract DE-ACO3-76SF00515
We describe an integrated relational database for beamline element configuration and online accelerator modelling for LCLS. It is hosted in Oracle, from which online controls software, optimization applications and feedback, use a programming interface to acquire the element data and model. Database population is by an automated process starting with a MAD deck, which is processed in Matlab to derive text files that describe the beamline elements whose data are uploaded using Oracle Loader, and the resulting Oracle APEX applications and reports are used for survey, cabling, metrology and other facilities. An automated facility for online model generation creates an XAL online model beamline description file using a database query; the resulting model is then tracked, and results can be loaded back into the database. As such, both the design or extant machine model, of the present and all previous model runs are available, and linked to the relevant element configuration. We present the process flow from the MAD design to the database, the database schema, the database applications, the process of generating a machine model, and some scientific software which uses the database.
CIAE, Beijing
TRIUMF, Vancouver
As a high intensity compact cyclotron, CYCIAE-100 is designed to provide proton beams in two directions simultaneously. At the extraction region, the fringe field of the main and the field of the combination magnet will influence the beam optics. The fringe field may become critical by comparison with the separated sector machine because of the compact structure. The dispersion during the beam extraction should not be ignored, which may make the beam envelop become evidently bigger. Then the beam loss and residual radiation increase. To study the beam optics at the extraction region of CYCIAE-100, the orbit tracking and transfer matrix calculation and symplectic by function extension of the code GOBLIN and modification of STRIPUBC have been implemented. The characteristics of the extracted beam have been investigated based on the main field from a FEM code and overlapping with the field generated from the combination magnet at each extraction port. The results are also compared with those from the CIAE’s code CYCTRS to confirm this precise prediction. The transfer matrix from this simulation is analyzed and used for the down stream beam line design.
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).