Paper  Title  Page 

MOPD05  Dynamic Aperture and Space Charge Effect Studies for the Recycler Ring for ProjectX  45 


A simplified Recycler lattice was created to fine tune injection straight, ring tune, and phase trombone. In this paper, we will present detailed modifications for further optimization of Recycler lattice which require the investigation of tune footprint and dynamic aperture based on higher order momentum components of the magnetic fields, together with the space charge effects. 

MOPD06  Achieving High Luminosity in an ElectronIon Collider  49 


The conceptual design of a polarized ringring electronion collider based on the CEBAF recirculated electron SRF linac relies on high repetition rate and high averaged current ion beams with very short bunch length and very small transverse emittance for reaching ultra high collider luminosity, up to middle of 10^{34} s^{1}cm^{2}. Nevertheless, making of such ion beams is a significant challenge, depending on various accelerator R&D including ion source, SRF linac, staged electron cooling and crab crossing at interaction points. In this paper, we will present some new ideas and concepts towards to realization of high collider luminosities, as well as preliminary conceptual design of various components of an ion complex that is capable to create such ion beams. 

MOPD07  New, High Power, Scaling, FFAG Driver Ring Designs  54 


High power driver rings are examined, using new FFAG designs, based on cells of five, scaling symmetrical pumplet magnets. Apertures are minimized by using large, betatron phase shifts per cell, typically μh ~ 280° and μv ~ 130°. Key aspects are the lengths of the long straight sections, particularly IF Hˉ charge exchange injection is required. Rings are considered for ISIS upgrades and Neutrino Factory proton and muon drivers. both with and without insertions. 

MOPD08  Beam Based Alignment of Synchrotorn under Coupled Quadrupole Magnet Environment  57 


The Beam Based Alignment (BBA) of the BPM is inevitable for precise and absolute beam position measurements. Even though careful fabrication and installation of the BPM detector, it has to be calibrated by using the beam. Usually, it requires that the individual quadrupole magnet is able to be controlled. However, it is not always that case. In addition, scanning over the all BPM is time consuming procedure. The BBA method under coupled QM environment would help to reduce time for calibration. It presents general formula and experiences at JPARC RCS and parts of results are compared with the ordinal method at JPARC MR. 

MOPD09  IBS for NonGaussian Distributions  62 


Standard models of the intrabeam scattering (IBS) are based on the growth of the rms beam parameters for a Gaussian beam distribution. However, in many situations distribution can significantly deviate from Gaussian which requires accurate treatment of IBS. Our original interest in this problem was motivated for the need to have accurate description of beam evolution due to IBS while distribution is strongly affected by external electron cooling force [1]. A variety of models with various degrees of approximation were implemented in BETACOOL in the past to address this topic [2]. A more complete treatment based on the friction coefficient and full 3D diffusion tensor was introduced in BETACOOL at the end of 2007 under the name “local IBS” [3]. Such a model allowed us calculation of IBS for arbitrary beam distributions. Numerical benchmarking of this local IBS model and its comparison with other models was reported before. Here, after briefly describing the model and its limitations, we present its comparison with available experimental data. [1] A. Fedotov et al., Proc. of PAC05 (Knoxville, TN), p. 4263. 

MOPD10  Linear and NonLinear Optimization of the PS2 Negative Momentum Compaction Lattice  67 


PS2 is a design study of a conventional magnet synchrotron considered to replace the existing PS at CERN. In this paper, studies on different aspect of single particle dynamics in the nominal PS2 Negative Momentum Compaction lattice are described. The global tuning flexibility of the ring and the geometric acceptance is demonstrated by a systematic scan of quadrupole settings. Frequency map analysis and dynamic aperture plots for two different chromaticity correction schemes are presented. The impact of magnet misalignments on the dynamic aperture is studied for one of them. A first study of the beam dynamics with magnetic multipole errors using frequency maps and the corresponding analytical tunespread footprints is reported. It is thus demonstrated that multipole errors determine to a large extend the beam dynamics in PS2. 

MOPD11  Spacecharge Effects during Multiturn Injection in SIS18  72 


For the FAIR project, the intensity of heavyion beams in SIS18 has to be increased by an order of magnitude. In order to achieve the design intensities, the efficiency of the multiturn injection from the UNILAC has to be optimized for high beam currents. This is especially important for the operation with intermediate charge state heavyions, where beam loss during injection will lead to pressure bumps and to a reduced lifetime of the beam. The multiturn injection into SIS18 is studied by virtue of particle tracking simulations using an extended version of the computer code PATRIC. The impact of space charge and other intensity effects on the efficiency of the injection process is analyzed. 

MOPD12  Reducing Losses and Emittance in High Intensity Linac at BNL  77 


The most important parameter for the high intensity linacs are the losses. The losses are about limited to 1W/m for the hand on maintenance requirements. This limit translates about 1 nA at 1 GeV and 100 nA at 10 MeV. Therefore less attention are paid to physics design low energy area, especially for the longitudinal plane which is responsible for the implanting nonlinearity in the particle distribution which are often responsible for the losses at high energies. We will present upgrade for BNL 200 MeV linac in the low energy and medium energy transport system. We were able to reduce the transverse emittance by more than factor of two and losses in the entire linac complex by order of magnitude. 

MOPD14  The EMMA Accelerator and Implications for Hadron NonScaling FFAGs  82 


The EMMA (Electron Model for Many Applications) accelerator is the world’s first nonscaling FFAG constructed at the Daresbury Laboratory, UK. Commissioning activities have recently been undertaken and beam dynamics results relevant to hadron nonscaling FFAGs are presented. The impact of these results on the future design of nonscaling FFAGs for high intensity hadron beam applications is discussed. 

MOPD15  Controlled Longitudinal Emittance Blowup in Double Harmonic RF System at CERN SPS  86 


Controlled longitudinal emittance blowup together with a fourth harmonic RF system are two techniques that are being used in the SPS in order to stabilize the beam before injecting into the LHC. The emittance blowup has been achieved by introducing a bandlimited phase noise during acceleration. Measured variations of the final emittance along the batch can be explained by the modification of the synchrotron frequency distribution due to the effect of beam loading in a double harmonic RF system. 

MOPD16  Simulation of the Long Term Beam Intensity Performance of the NEGcoated SIS18  91 


The StrahlSim code was developed to simulate dynamic vacuum effects and charge exchange beam loss in heavy ion accelerators. The code accounts for the charge exchange cross sections at the actual beam energy, the loss positions of charge exchanged ions, and the pressure rise caused by desorption due to the impact of these ions onto the vacuum chamber. Recent progress was made by implementing time dependent longitudinal pressure profiles in StrahlSim. This allows to simulate localized pressure bumps during a cycle and therefore to estimate the lifetime of NEGcoated surfaces depending on their positions in the ring, and the corresponding influence on the beam performance over the saturation process. The new code was applied to SIS18 considering two scenarios. One calculation has been carried out for the currently available U^{28+} intensities of 2·10^{10} extracted particles per cycle, and the other calculation for the proposed FAIR booster operation with 1.5·10^{11} extracted particles per cycle. Results for both scenarios will be presented in this work. 

MOPD19  Vertical Orbit Excursion FFAGs  96 


Fixedfield strong focussing accelerators (FFAGs), in which the beam orbit moves with increasing momentum into higher field regions, have been widely studied. Less wellknown is that the central orbit does not need to move outwards with energy: it can move in any direction including the verticallymoving orbit discussed in this paper. This allows for a magnet design with a smaller magnetised volume for a larger total energy range. A vertical analogue to the scaling FFAG is defined and its dynamic aperture studied for the case of an energy booster to the 800MeV ISIS synchrotron at RAL with various possible lattices. 

MOPD21  Transverse Decoherence in Bunches with Space Charge  101 


Transverse bunch offsets typically occur after bunchtobucket transfer between synchrotrons. Decoherence of the oscillations can cause emittance growth and beam loss, which should be avoided in highintensity synchrotrons, like the projected SIS100 synchrotron of the FAIR project. In this contribution we investigate how space charge and impedances modify the bunch decoherence and associated diagnostics methods as turnbyturn chromaticity measurements. Results of machine experiments at the SIS18 synchrotron are compared with particle tracking simulations. 

MOPD23  Study on Slow Extraction from SIS100 with High Intensity  106 


The SIS100 heavy ion synchrotron will play a key role within the future FAIR project underway at GSI. Although it is optimized for fast extraction, also slow extraction will be used. Slow extraction is based on the excitation of a third order resonance leading to the formation of a stable triangular phase space area. During the extraction process, particles leave this area along separatrices, where they pass the blade of the electrostatic septum under a certain angle. Even in a low current regime the spread in the particle momenta leads to a spread in this angle which causes particle loss, in particular, at the blade of the electrostatic septum. As a consequence the septum blade as well as the subsequent magnets will be irradiated. At high beam intensities space charge or electron clouds cause an additional tune spread which could increase the particle loss. In our study we model the extraction process and estimate the losses for high beam intensities. 

MOPD25  Using Electron Cooling for Obtaining Ion Beam with High Intensity and Brightness  110 


Electron cooling is used for damping both transverse and longitudinal oscillation of heavy particle. This effect is widely used in the existing and be designing storage rings. This article describes the last experiments with electron cooling carried out on the coolers (LEIR, EC300, EC35) produced by BINP. The ultimate sizes of the ion beam are discussed. The accumulated experience may be used for the project of electron cooler on 2 MeV (COSY) for obtaining high intensity proton beam with internal target. Using electron beam enables to have physics experiment with high quality of the ion beams at despite of the target interaction. The combination of the electron cooler with carbon storage ring can be used for cancer therapy because it enables to storage high number of the ion and to realize the original extraction scheme such as recombination or pellet extraction 

TUO1C01  Coupling Impedances of a Short Insert in the Vacuum Chamber  348 


We have developed a theory to calculate both longitudinal and transverse impedances of a resistive short (typically shorter than the chamber radius) insert with cylindrical symmetry, sandwiched by perfectly conductive chambers on both sides. It is found that unless the insert becomes extremely thin (typically a few nm for a metallic insert) the entire image current runs on the thin insert, even in the frequency range where the skin depth exceeds the insert thickness, and therefore the impedance increases drastically from the conventional resistivewall impedance. In other words, the wake fields do not leak out of the insert unless it is extremely thin. 



TUO1C02  Impedances of Two Dimensional Multilayer Cylindrical and Flat Chambers in the NonUltrarelativistic Case  353 


Two dimensional electromagnetic models (i.e. assuming an infinite length) for the vacuum chamber elements in a synchrotron are often quite useful to give a first estimate of the total beamcoupling impedance. In these models, classical approximations can fail under certain conditions of frequency or material properties. We present here two formalisms for flat and cylindrical geometries, enabling the computation of fields and impedances in the multilayer case without any assumption on the frequency, beam velocity or material properties (except linearity, isotropy and homogeneity). 



TUO1C03  Van Kampen Modes for Bunch Longitudinal Motion  358 


In 1955, van Kampen described a full set of eigenfunctions for collective oscillations in plasma. This formalism can be applied to the beams as well. As a result, a loss of Landau damping is seen as one of the main reasons for bunch instability. Bunch stability is seen to depend both on a shape of the distribution function and RF bucket. Available areas on intensityemittance plane are shown for various RF shapes and wake functions. Results are compared with observations and simulations. 



TUO1C04  Longitudinal Peak Detected Schottky Spectrum  363 


The peak detected Schottky spectrum is used for beam observation in the CERN SPS and now already in the LHC. This tool was always believed, however without proof, to give a good picture of the particle distribution in synchrotron frequencies similar to the longitudinal Schottky spectrum of unbunched beam for revolution frequencies. The analysis shows that for an optimised experimental setup the spectrum of the peak detected signal is very close to the synchrotron frequency distribution inside the bunch  much closer than that given by the traditional longitudinal bunchedbeam Schottky spectrum. The limitations of the present experimental setup in the SPS are discussed together with possible improvements. 



TUO1C05  Transverse Schottky and BTF Measurements and Simulations in Spacecharge Affected Coasting Ion Beams  368 


A study of the transverse dynamics of coasting ion beams with moderate space charge is presented. An analytic model based on the dispersion relation with a linear spacecharge force is used to describe the impact of space charge on transverse beam transfer functions (BTFs) and the stability limits of a beam. The dielectric function obtained in this way is employed to describe the transverse Schottky spectrum with linear space charge as well. The difference between space charge and impedance effects is highlighted. An experiment performed in the heavy ion synchrotron SIS18 at GSI to detect spacecharge effects at different beam intensities is explicated. The measured transverse Schottky spectra, BTFs and stability diagrams are compared with the analytic model. The spacecharge parameters evaluated from the Schottky and BTF measurements are compared with estimations based on measured beam parameters. Furthermore, particle tracking simulations demonstrating the impact of collective effects on the Schottky and BTF diagnostics are presented. The simulation results are used to verify the spacecharge model. 



TUO1C06  Studies of the Effect of 2nd Harmonic on the ep Instability and RF Control of Instabilities  373 


The dependence of the ep instability threshold on the 2nd harmonic voltage and on the longitudinal profile in general is observed in the SNS ring. Possible explanations of this phenomenon are discussed in the paper. The most optimal RF configuration to mitigate instabilities is presented. 



WEO1A01  Effect of Space Charge on Instabilities  410 


A purely imaginary Space Charge Impedance (SCI) is a part of the entire impedance which takes into account local electromagnetic field carried by a beam only. Such impedance is unable to cause the beam instability by itself (negative mass instability is the unique exclusion derived from a lack of longitudinal focusing in coasting beams). Real part of the impedance is just the one directly responsible for the instability, and it is generated by any retarding (wake) field. However, SCI affects on all the instability characteristics including threshold, frequency, ramp rate and shape of intrabunch oscillations (headtale modes). This influence can be crucially important in proton synchrotrons where SCI, typically, constitutes a significant or even dominant part of the impedance. In such conditions, the wake field can be treated as a small perturbation which controls parameters of collective beam modes at given headtale bunch mode. This talk is designated to analyze the mentioned effects in frames of these assumptions. The emphasis is on the problem of transverse oscillations of a bunched beam. 



WEO1A02  HeadTail Bunch Dynamics with Space Charge  415 


Significant progress has been made recently in the understanding of the effects of direct space charge on the transverse headtail bunch dynamics. Different analytic approaches for headtail modes in bunches for different spacecharge parameter regimes have been suggested. Besides headtail eigenmode characteristics, Landau damping in a bunch exclusively due to space charge has been predicted. In this contribution we compare results of particle tracking simulations with theoretical predictions for the eigenfrequencies and eigenfunctions of headtail modes in a Gaussian bunch. We demonstrate the spacecharge induced Landau damping in a bunch and quantify damping rates for different modes and spacecharge tune shifts. Under conditions below the mode coupling threshold we study the headtail instability with space charge. Our results show that the spacecharge induced damping can suppress the instability for moderately strong space charge. For strong space charge the instability growth rates asymptotically reach constant vales, in agreement with theoretical predictions. 



WEO1A03  The Study of Space Charge Effects for CSNS  420 


The China Spallation Neutron Source (CSNS) accelerator operates at 25 Hz repetition rate with an initial design beam power of 100 kW and is upgradeable to 500 kW. The accelerator of CSNS consists of a low energy linac and a Rapid Cycling Synchrotron (RCS). In this kind of high power accelerators, especially in the low energy end, the beam is space charge dominated, and the space charge effects are the main source of beam loss. The space charge effects limit the maximum beam density, as well as beam power. Many simulation works were done for the study of space charge effects for CSNS accelerators, by using code ORBIT , SIMPSONS and PARMILA. Various conditions are considered in simulations, including the effects of different lattice structure, different tune, the combine effect of sextupole field and space charge, the combine effects of higher order field, error and space charge effects, different painting beam distribution for RCS, etc. The beam loss and emittance growth are compared for different conditions. A brief introduction to beam dynamics design is also given. 



WEO1A04  Simulation of Space Charge Effects in JPARC  425 


Nonlinear space charge interaction in high intensity proton rings causes beam loss, which limits the performance. Simulations based on the particle in cell (PIC) method has been performed for JPARCRapid Cycle Synchrotron (RCS) and Main Ring (MR). Beam loss estimation during acceleration and resonances analysis are discussed with various simulations using dynamic and frozen models. 



THO2B03  Operation of the JPARC Main Ring with the Moderate Beam Power: Predictions and Observations.  610 


From April 2010 the routine operation of the JPARC Main Ring for the Neutrino experiments has begun, providing the moderate beam power at the maximum energy of 30GeV. The beam intensity delivered to Main Ring from the booster (rapid cycling synchrotron, JPARC RCS) is about 1.25·10^{13} protons per bunch, which corresponds to the beam power of 300kW at the energy of 3GeV. The maximum expected beam power from Main Ring for the ‘phass^{1}’ stage is about 145kW (8 bunches operation, the repetition time is 3.3 sec). To optimize the machine performance, providing minimum particle losses during the injection and acceleration processes, the computational model of the JPARC Main Ring has been established. In frame of this report the comparison between predictions, based on the corresponding simulations, and measured beam losses for different ‘bare’ tunes is performed. The effects of the linear coupling correction at the moderate beam power are analyzed for the JPARC Main Ring operation. The predicted and obtained budget of the lost beam for the machine operation with the moderate beam power is presented. The basic scenario for the high beam power operation will be discussed shortly. 



THO2B04  Long Term Simulations of the Space Charge and Beam Loss in the SIS18  615 


In this contribution we present the simulations of the experiment made in the SIS18 synchrotron on the effect of the space charge in a bunched beam stored for one second. To the simulations a discussion of the underlying dominant effect (trapping or scattering?) is included. A discussion on the consequences of this beam dynamic regime on the SIS100 is presented, open issues and future (experimental and numerical) studies are outlined. 



THO2B05  High Intensity Studies on the ISIS Synchrotron, Including Key Factors for Upgrades and the Effects of Half Integer Resonance.  619 


ISIS is the spallation neutron source at Rutherford Appleton Laboratory in the UK. Operation centres on a high intensity proton synchrotron, accelerating 3·10^{13} ppp from 70800 MeV, at a rep rate of 50 Hz. Studies are under way looking at many aspects of high intensity behaviour, with a view to increasing operational intensity, identifying optimal upgrade routes and understanding more about fundamental intensity limitations. Present work is assessing the possibility of increasing beam power by raising injection energy into the present ring (~180 MeV), with a new optimised injector. Progress on calculations and simulations for the main high intensity topics is presented, including: space charge and emittance evolution in the transverse and longitudinal planes, beam stability and injection optimisation. Of particular interest is the space charge limit imposed by half integer resonance, for which latest experimental and simulation results are reviewed. Results from measurement and 3D simulation of the present operational machine are also summarised, along with investigations of the observed loss mechanisms. Finally, future plans are outlined. 



THO1C01  Tune Resonance Phenomena in the SPS and Related Machine Protection  624 


The 7 km long CERN Super Proton Synchrotron (SPS) is, apart from the LHC, the accelerator with the largest stored beam energy worldwide of up to 3 MJ. In 2008, an equipment failure led to a fast tune shift towards an integer resonance and an uncontrolled loss of a high intensity beam, which resulted in major damage of the accelerator. Distinct experimental studies and simulations provide clear understanding of the beam dynamics and the beam loss pattern at different SPS tune resonances. Diverging closed orbit oscillations, a resonant dispersion and increased beta beating are the driving effects that lead to a complete beam loss in as little as 3 turns (69μs). At the moment, the commissioning of a new turnbyturn position interlock system which will counteract the vulnerability of the SPS is ongoing. 



THO1C02  High Intensity Beam Physics at UMER  629 


We report on progress of studies of transverse and longitudinal spacecharge beam physics at the University of Maryland electron ring (UMER), a lowenergy, high current recirculator. The transverse beam dynamics studies include measurements of betatron and dispersion functions as well as linear resonances for a number of beam currents. We also discuss the implementation of induction focusing for the longitudinal containment of the lowest current beam. When complemented with optimized orbit steering, this longitudinal beam focusing has made possible to extend the number of turns from 100 to more than 1,000, limited mostly by electronics. Some of the results presented are compared with calculations and simulations with the computer codes ELEGANT and WARP. 



THO1C03  Interplay of Spacecharge and Beambeam Effects in a Collider  634 


There is a strong interest in heavyion collisions at the center of mass energies of 520 GeV/nucleon. This physics program is motivated by a search of the QCD phase transition critical point. Such lowenergy operations started at Relativistic Heavy Ion Collider (RHIC) in 2010. The defining limitation in luminosity improvement for this program is expected to be due to the space charge. For RHIC, we are interested in rather long beam lifetime, which sets limitation on an allowable spacecharge tune shift. An additional complication comes from the fact that ion beams are colliding, which requires careful consideration of the interplay of direct spacecharge and beambeam effects. We started to explore these beam dynamics effects in RHIC Accelerator Physics Experiments (APEX) in 2009 with proton beams. The experiments continued in 2010 with Au ion beams. This paper summarizes our findings and observations. 



THO1C04  Application of a Localized Chaos Generated by RFphase Modulations in PhaseSpace Dilution  639 


Physics of chaos in a localized phasespace region is exploited to produce a longitudinally uniformly distributed beam. Theoretical study and numerical simulations are used to study its origin and its applicability in phase dilution of beam bunch. Through phase modulation to a doublerf system, a central region of localized chaos bounded by invariant tori are generated by overlapping parametric resonances. Condition and stability of the chaos will be analyzed. Applications of such a chaotic phasespace dilution system are high power beam, beam distribution uniformization, and industrial beam irradiation. 



THO1C05  Optical Stochastic Cooing in Tevatron  644 


The intrabeam scattering is the major reason of fast luminosity degradation in the Tevatron. It results in that in the case of optimal operation only about 40% of antiprotons are used to the store end and the rest are discarded. The beam cooling is the only effective remedy to mitigate this problem. Unfortunately neither electron or stochastic cooling can be effective at the Tevatron energy and bunch density. Thus the optical stochastic cooling is the only promising technology capable to cool the Tevatron beam. The paper circuses possible ways of such cooling implementation in Tevatron as well as advances in optical stochastic cooling theory. The technique looks promising and potentially can double the average Tevatron luminosity without increasing its peak value. 



THO1C06  Electron Cooled Beam Losses Phenomena in COSY  649 


Experimentally it has been shown the achievable intensity of electron cooled beams at COSY is restricted by three main beam loss phenomena: the initial losses just after injection during 510 s of beam cooling, the coherent selfexcited oscillation of cooled beam and the longterm losses ~ n x 1000 s. The second was successfully investigated and damped by the feedback system. In this work we study the first and third types of loss. Since the most important losses are suspected to be due to the single Coulomb scattering we have investigated the dynamic aperture with the electron beam as main source of nonlinearity. We analytically and numerically studied how the dynamic aperture depends on an electron beam, in particular, value of its current, distribution, displacement relatively of proton beam and finally on TWISSparameters in the cooler location. As a result we have concluded, that each of them influences on the dynamic aperture everyone in own way. In paper we compare the theoretical and experimental results. 



THO1D01  Nonlinear Optics as a Path to HighIntensity Circular Machines  676 


In present circular machines the beam intensity is often limited by the following phenomena: machine resonances, various tune shifts (and spreads), and instabilities. In this paper we will propose a path toward alleviating these phenomena by making accelerators nonlinear as well as integrable. 



THO1D02  Transverse Mode Coupling Instability Measurements at Transition Crossing in the CERN PS  681 


Crossing transition energy in the CERN PS is critical for the stability of high intensity beams, even with the use of a second order gamma transition jump scheme. The intense single bunch beam used for the neutron TimeofFlight facility (nToF) needs a controlled longitudinal emittance blowup at the flat bottom to prevent a fast singlebunch vertical instability from developing near transition. This instability is believed to be a Transverse Mode Coupling (TMCI) type. A series of measurements performed in 2009 and 2010 aims at using this TMCI observed on the ToF beam at transition, as a tool for estimating the transverse global impedance of the PS. For this purpose, we compare the measurement results with the predictions of the HEADTAIL code and find the matching parameters. This will allow predicting the stability of the high brightness LHC beam near transition. The final goal is to study the feasability of a possible cure to the fast vertical instability measured on the ToF beam by applying an improved gamma transition jump scheme instead of compromising the longitudinal density. 



THO1D03  Fast Compression of Intense HeavyIon Bunches in SIS18  686 


At GSI and for the FAIR project short heavyion bunches are required for the production and storage of exotic fragment beams as well as for plasma physics applications. In the SIS18 and in the projected SIS100 synchrotron longitudinal compression via fast bunch rotation is performed directly before extraction. In order to arrive at the required bunch length the rf cycle has to be optimized for high intensities to avoid the blowup of the occupied longitudinal phase space area. We will discuss experimental and simulation results of the rf capture at injection energy, the rebunching process at the final energy and the subsequent bunch rotation. 

