IPAC2014 - Classification: 05 Beam Dynamics and Electromagnetic Fields / D02 Non-linear Dynamics

Paper	Title	Page
THPRO028	Bunch Compressor Design for CLIC Drive Beam	2924
	A.A. Aksoy Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey J. Esberg, D. Schulte CERN, Geneva, Switzerland
	The drive-beam linac which is required for generation RF power at Compact Linear Collider (CLIC) has to accelerate an electron beam with 8.4 nC per bunch up to 2.4 GeV in almost fully loaded structures. The required beam stability in both transverse and longitudinal directions are of concern for such a high bunch charge. We present different bunch compressor designs for the Drive Beam and compare their performance including the effects beam energy and phase jitters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO028
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THPRO055	Electron Beam Final Focus System for Thomson Scattering at ELBE	2995
	J.M. Krämer, F. Bødker, A. Baurichter, M. Budde Danfysik A/S, Taastrup, Denmark A. Irman, U. Schramm Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany U. Lehnert, P. Michel HZDR, Dresden, Germany
	Funding: This work is part of LA3NET and funded by European Commission under Grant Agreement Number 289191. The design of an electron beam Final Focus System (FFS) aiming for high-flux laser-Thomson backscattering x-ray sources at ELBE* is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole triplet. This allows sub-ps electron beam focusing to match the laser spot size at the interaction point. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. Since the electron beam is chirped for bunch compression upstream, the rms energy spread is increased to one or two percent and second order chromatic effects must be taken into account. For an emittance of 13 pi mm mrad, we predict rms spot sizes of about 40 um and divergences of about 15 mrad. We also present the design of the permanent magnet quadrupoles to be used for the FFS. Ferromagnetic poles ensure a high field quality and adjustable shunts allow for fine adjustment of the field strength and compensation of deviations in the permanent magnet material. *A. Jochmann et al., Phys. Rev. Lett. 111 (2013) 114803
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THPRO056	Estimation of Systematic Errors for Deuteron Electric Dipole Moment (EDM) Search at a Storage Ring	2998
	S. Chekmenev RWTH, Aachen, Germany
	An experimental method which is aimed to find a permanent EDM of a charged particle was proposed by JEDI (Jülich Electric Dipole moment Investigations) collaboration in 2012. EDMs can be observed by their small influence on spin motion. The only possible way to perform a direct measurement is to use a storage ring. For this purpose it was decided to carry out the first precursor experiment at the Cooler Synchrotron (COSY). Since the EDM of a particle violates CP invariance and is expected to be tiny, treatment of all various sources of systematic errors should be done with a great level of precision. One should clearly understand how misalignments of the magnets affects the beam and the spin motion. In reality, one of the methods to investigate spin behavior in the presence of misalignments in a storage ring is to mimic their influence on the beam parameters using small orbit kicks with different amplitudes. In this talk the first simulations of orbit excitations will be discussed. The corresponding spin tune shifts will be considered. The influence of the distorted orbit on the polarization build-up caused by the EDM will be examined. A. Lehrach, F. Rathmann, J. Pretz et al., "Search for Permanent Electric Dipole Moments at COSY. Step 1: Spin coherence and systematic error studies", 2012
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THPRO057	Advanced Magnetic Field Description and Measurements on Curved Accelerator Magnets	3002
	P. Schnizer, E.S. Fischer, A. Mierau GSI, Darmstadt, Germany P.G. Akishin JINR, Dubna, Moscow Region, Russia B. Schnizer TUG/ITP, Graz, Austria
	The SIS100 accelerator will be built within the first realisation phase of the FAIR project. The series production of its superconducting bending magnets was started without any test model in 2013. This time saving strategy requires a careful investigation of the magnetic field quality for the first manufactured dipole. The consequences of the curved magnet design was analysed developing advanced multipoles for elliptical and toroidal magnet geometries. We present the theoretical results together with measured data obtained for the first of series dipole. A description of the rotating coil probe based measurement method will be given together with the achieved field quality as well as an estimation of the limits of the chosen field representation and its beam dynamics interpretation.
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THPRO058	Study of the “Particle-in-Cell” Induced Noise on High Intensity Beams	3005
SUSPSNE055	use link to see paper's listing under its alternate paper code
	F. Kesting, G. Franchetti GSI, Darmstadt, Germany U. Ratzinger IAP, Frankfurt am Main, Germany
	Numerical noise in PIC codes produces artifacts which affects long term beam simulations needed for accelerator as the SIS100. A detailed study on the effect of numerical noise occurring in multi-particle tracking codes is presented. The influence of the granularity of particle distributions and the fineness of the meshes of Poisson solvers on the particle dynamics was studied. These results are used to discuss the effect of the PIC numerical noise in a long term space charge benchmarking study.
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THPRO059	Simulation Study on Beam Loss in the Alpha Bucket Regime during SIS-100 Proton Operation	3008
	S. Sorge GSI, Darmstadt, Germany
	Besides heavy ion operation, the heavy ion synchrotron SIS-100 will accelerate a single proton bunch of N=2*10¹³ particles up to the energy E=29 GeV. For the present standard scenario, optics settings have been developed which provide a transition energy according to gamma_tr=45.5 in order to avoid transition crossing during acceleration. At extraction energy the corresponding nonlinear momentum compaction and phase slip factors cause the formation of a so called alpha bucket. In this contribution we present the results of transverse beam loss tracking studies in the alpha bucket regime. The effects of momentum spread, magnet errors and residual closed orbit distortion are analyzed.
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THPRO060	Beam-beam Effect on the BTF in Bunched Beams	3011
SUSPSNE053	use link to see paper's listing under its alternate paper code
	P.A. Görgen, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany W. Fischer BNL, Upton, Long Island, New York, USA
	We present studies on the transverse baseband Beam Transfer Functions (BTFs) in bunched beams at high energies. The goal of the work is to evaluate whether transverse BTFs can be used to diagnose the tune spread arising from transverse nonlinearities such as the beam-beam effect and space charge. We employ an analytic expression to the BTFs of beams under a transverse nonlinear lens arising from a bi-Gaussian charge distribution. We obtain agreement between a simulation model of an electron-lens like configuration and the analytic results. The tune spread for this scenario can be recovered by means of a fit against the analytic expectation. The results are compared with measurements where the beam-beam effect acts as a substitute for the electron lens. A similar behaviour of the BTF is observed. This allows the conclusion that the transverse BTF can be used to diagnose tune spread from an electron-lens. Finally we discuss the problems that arise when trying to recover the tune spread from BTFs of arbitrary non-Gaussian beams and in the presence of coherent beam-beam modes.
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THPRO061	New and Unifying Formalism for Study of Particle-Spin Dynamics Using Tools Distilled From Theory of Bundles	3014
	K.A. Heinemann, J.A. Ellison UNM, Albuquerque, New Mexico, USA D.P. Barber Cockcroft Institute, Warrington, Cheshire, United Kingdom D.P. Barber, M. Vogt DESY, Hamburg, Germany
	Funding: The work of JAE and KH was supported by DOE under DE-FG-99ER41104 and the work of DPB and MV was supported by DESY. We summarize our recent work on spin motion in storage rings . In fact we return to our study * of spin motion in storage rings. We again focus on spin tunes, polarization fields etc. but in contrast to ** we base the description on one turn maps and refine and expand our toolset from that in * by using a rather modern method from Dynamical-Systems theory, developed in the 1980's by R. Zimmer and others based on bundles , . With this we obtain new insights into invariant spin fields, invariant frame fields, spin tunes and spin-orbit resonances. At the same time we get a unified way to treat spin-1/2 and spin-1 particles. The bundle aspect is pointed out and we briefly mention the relation to Yang-Mills Theory as well. K.Heinemann, D.P.Barber, J.A.Ellison, M.Vogt. To be submitted. D.P.B., J.A.E., K.H., PRSTAB 7 (2004) 124002. * K.Heinemann, PhD Thesis, University of New Mexico, 2010 (available on the web).
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THPRO062	Spin Tune Decoherence in Multipole Fields	3017
	Y. Senichev, A.N. Ivanov, A. Lehrach, R. Maier, D. Zyuzin FZJ, Jülich, Germany S.N. Andrianov St. Petersburg State University, St. Petersburg, Russia
	This article analyzes possible limitations in the method to search for the electric dipole moment (EDM) using polarized particles in a storage ring. It is well known that for detection of the electric dipole moment one needs to create such conditions where the particle's spin oscillations can be caused only by the EDM. Really, there are two possible methods for EDM search using a storage ring: resonant spin buildup in a magnetostatic ring and “frozen” spin method in an electrostatic ring with “magic” energy. Both methods have common limitations caused by spin decoherence. In the frame of self consistent theory the reasons of the spin decoherence are classified independently on method and discussed taking into consideration multipole components of external fields, as well as the nonlinearities of RF fields.
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THPRO063	Spin Tune Parametric Resonance Investigation	3020
	Y. Senichev, A.N. Ivanov, A. Lehrach, R. Maier, D. Zyuzin FZJ, Jülich, Germany S.N. Andrianov St. Petersburg State University, St. Petersburg, Russia
	The idea of resonant spin oscillation method was modernized and improved in Forschungszentrum Julich in the proposed experiment at the COSY ring. The resonant method is based on spin tune parameterization using transverse RF magnetic or/and electric field. The spin orientation smearing due to the finite spin coherence time (SCT) plays a crucial in the proposed experiment to search for the electric dipole moment. Our analysis is based on the T-BMT differential equations for spin together with shorten motion equations. Using well developed theory of Mathieu's differential equations we have got simplified analytic solution for prediction of spin behavior. In this paper we have numerically evaluated all effects having fundamental contributions from our point of view.
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THPRO064	Effect of Laser-plasma Channeling on Third-harmonic Radiation Generation	3023
	M. Singh, D.N. Gupta University of Delhi, Delhi, India
	An intense Gaussian laser beam, propagating through a magnetized plasma, becomes self-focused due to the ponderomotive force on the electrons. The magnetic field reduces the radius of the laser beam and enhances the self focusing of the laser beam. The self-sustained plasma channel can affect the efficiency of harmonic generation of the interacting laser beam. The radial density gradient of the channel beats with the oscillatory electron velocity to produce density perturbation at laser frequency. The ponderomotive force at second-harmonic frequency produces electrons density oscillations that beat with the oscillatory velocity to create a non-linear current, driving the third harmonic radiation. The velocity and density perturbation associated with the self-focused laser beam generates a nonlinear current at triple fold frequency of the fundamental laser. Our results show that the efficiency of third-harmonic generation of the laser beam is affected significantly due to the self-sustained plasma channel. The strength of magnetic field play a crucial role in efficiency enhancement of third-harmonic generation.
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THPRO065	De-coherence Study of Betatron Oscillation for the Beam Shape Manipulation	3026
	Y. Shoji LASTI, Hyogo, Japan
	In electron storage ring a temporal perturbation to the beam makes spatial structure in a bunch, which emit short X-ray or coherent THz radiation. For this technique of bunch shape manipulation, it is important to reduce unwanted de-coherence of betatron motion, which would break the intended spatial structure. At NewSUBARU, 1.5 GeV storage ring, we kicked the beam using a vertical fast kicker and investigated the de-coherence of betetron oscillation using mainly a dual-sweep streak camera. The largest is the Landau damping by a well-known chromatic tune spread, although the phase spread comes back to zero at after a synchrotron oscillation period. On the other hand, there exists several non-linear effects, which makes accumulation of the oscillation phase spread. These are, horizontal betatron amplitude dependent vertical tune shift, synchrotron oscillation amplitude dependent synchrotron tune shift, non-linear chromaticity, synchrotron oscillation chromaticity (non-symmetry of rf bucket), longitudinal radiation excitation process, and others. The tuning knobs we had was some sets of non-linear magnets up to octupole and the rf voltage.
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THPRO066	Correction of the Higher Order Dispersion for Improving Momentum Acceptance	3029
	M. Takao, K.K. Kaneki, Y. Shimosaki, K. Soutome JASRI/SPring-8, Hyogo-ken, Japan
	May 2013 we lowered the emittance of the SPring-8 storage ring from 3.5 nm¥cdotrad to 2.4 nm¥cdotrad to enhance the brilliance. At the optics change the momentum acceptance shrunk from 3.2 ¥% to 2.4 ¥%. Then, by carefully correcting the second order dispersion, we recovered the momentum acceptance up to 2.8 ¥%, which results in doubling the Touschek beam lifetime. Although the injection efficiency decreased by more than 10 ¥% by the dispersion correction, we restored it by means of suppressing the amplitude dependent tune shift. Here we describe these improvements of the nonlinear dynamics of the SPring-8 storage ring.
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THPRO067	Modeling Slow Extraction Process For J-PARC Main Ring	3032
	A.Y. Molodozhentsev KEK, Ibaraki, Japan
	J-PARC Main Ring has to deliver the proton beam to ‘hadron’ experiments by using ‘slow extraction’ technique, base on the 3rd order horizontal resonance. The spill quality during the full extraction period is one of the most important requirements as well as the beam quality. The computer modeling of the slow extraction process for J-PARC Main Ring is based on a realistic machine model, which includes measured imperfections of the machine in addition to dynamic variation of the machine elements to perform the slow extraction. In frame of this report we represent the results of the modeling the slow extraction process from J-PARC Main Ring by using the PTC-ORBIT combined code. The resonance extraction has been controlled by changing the betatron tune. Control the horizontal emittance of the extracted beam has been performed by using ‘dynamic’ bumps. Control the spill quality of the extracted beam has been performed by using dedicated quadrupole magnets and the transverse RF signal (RF knockout). In addition, the spill quality can be improved by suppressing effect of the power supply ripple. On the request, the collective effects can be introduced into the model.
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THPRO068	Multipoles and Alignment Error Limits for the SESAME Storage Ring Magnets	3035
	M. Attal, E. Huttel SESAME, Allan, Jordan
	SESAME storage ring magnets are being constructed through the CESSAMag project in the frame of SESAME - CERN/EU collaboration. The impact of multipole and alignment errors of these magnets on machine performance have been investigated using different tracking codes. The tolerance of both systematic and random errors are defined. This article reports on the investigation results.
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THPRO070	Beam Dynamics Simulations in Cyclotron C230 Considering Imperfections of Magnetic Field Radial Component	3038
	E. Samsonov, S.A. Kostromin, N.A. Morozov, E. Syresin JINR, Dubna, Moscow Region, Russia
	Simulations concern to a beam axial motion in the IBA cyclotron C230 that is a base facility in several medical centers worldwide. Because of small axial focusing of the beam in a center of the cyclotron the radial component of magnetic field imperfections leads to additional proton losses. Measured maps of the axial and radial components of magnetic field were used in the simulations. It was found that the radial component with value 5-10 G in the center and approximately 2 G in the main region of acceleration leads to decrease of the resulting beam intensity by about two times and to increase the beam axial width by 25% as well. Simulations define the requirements to the experimental radial component shaping for the next cyclotrons of this series. Providing these requirements will ensure an absence of the additional proton losses due to the axial motion perturbations.
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THPRO071	Control of Calculations in the Beam Dynamics using Approximate Invariants	3041
	S.N. Andrianov St. Petersburg State University, St. Petersburg, Russia D. Zyuzin FZJ, Jülich, Germany
	One of the important problems in the theory of dynamical systems is to find corresponding (invariants). In this article we are discussing some problems of computing of invariant functions (invariants) for dynamical systems. These invariants can be used for describing of particle beams systems. The suggested method is constructive and based on the matrix formalism for Lie algebraic tools. We discuss two types of invariants: kinematic and dynamic. All calculations can be realized in symbolic forms, in particular, kinematic invariants are based on the theory of representations of Lie algebras (in particular, using the Casimir’s operators). For the case of nonlinear kinematic invariants we propose a recursive scheme, which can be implemented in symbolic forms using instruments of computer algebra (for example, such packages as Maple or Mathematica). The corresponding expressions for invariants can be used to control the correctness of computational experiments, first of all for long time beam dynamics.
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THPRO072	Field Parametrisation for the ESS Superconducting Cavities	3044
	T. Lindqvist Lund University, Lund, Sweden E. Laface ESS, Lund, Sweden
	Here we present a method for constructing a parametrization of the electric field in the superconducting elliptic cavities of the ESS linac. The parametrization is done by replicating the electric field from measured data using trigonometric and exponential functions. The field generated by the parameters exhibits a mean error of 0.28% ( maximum error of 3.8% and s.t.d. error 1.1%), with the advantage of only taking up a fraction of the required data. The field in the entire cavity is extrapolated by combining the Maxwell equations with the parametrized form of the field. We also present particle simulations based on the parametrization model to showcase some typical accelerator behaviour. Additionally we present a small extension of the parametrization method to also model spoke cavities.
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THPRO073	Longitudinal Acceptance Evaluation from Hamiltonian	3047
	E. Laface ESS, Lund, Sweden
	An RF cavity is designed around a reference particle; if the energy or the phase of a real particle are too far from the reference, the particle is lost. The widest area of energy-phase that allows a particle to be transported by the cavity is called acceptance of the cavity. In simulations the acceptance is evaluated tracking several particles with different energies and phases and marking when a particle is transmitted or lost. This process can be time consuming because of the large amount of tracked particles requested to characterise the cavity acceptance. In this paper we propose an alternative method to evaluate the acceptance studying directly the Hamiltonian associated to the cavity.
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THPRO074	Characterization of the Longitudinal Wakefields in the MAX IV Linac	3050
SUSPSNE054	use link to see paper's listing under its alternate paper code
	O. Karlberg, F. Curbis, S. Thorin, S. Werin MAX-lab, Lund, Sweden
	In the second part of 2014, the 3GeV linac at the MAX IV laboratory will enter its commissioning stage. Equipped with two guns, the linac will act as a full energy injector for the two storage rings and at the same time provide high brightness pulses to a Short Pulse Facility (SPF). Compression in the linac is done in two double achromats with fixed R56 that relies upon the RF phase introduced energy chirp, which in this case is strongly enhanced by the longitudinal wakefields. Since the longitudinal wakefields plays a major role in the compression and bunch shaping they need to be carefully investigated during the commissioning. In this proceeding we will discuss a measurement technique that will be used during commissioning to characterize the longitudinal wakefields and their precise effects on e.g. the bunch shape and the energy spread. Predictions obtained from particle tracking will be presented.
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THPRO075	High-chromaticity Optics for the MAX IV 1.5 GeV Storage Ring	3053
SUSPSNE056	use link to see paper's listing under its alternate paper code
	T. Olsson, S.C. Leemann MAX-lab, Lund, Sweden
	The MAX IV facility currently under construction in Lund, Sweden will include a 1.5 GeV storage ring. To prevent head-tail instability, the negative natural chromaticities of the MAX IV 1.5 GeV storage ring have been corrected to positive values using sextupole gradients in the focusing quadrupoles along with dedicated sextupole magnets. To allow adjustment of the chromaticity correction, weak correction sextupoles have been inserted into the lattice. A high-chromaticity optics has been developed for the MAX IV 1.5 GeV storage ring in case instability issues arise during commissioning. Two chromatic sextupole families were used to correct the linear chromaticity. The tune footprint was then tailored using the remaining two sextupole families with the goal of maximizing dynamic aperture and Touschek lifetime. This paper describes the recently developed high-chromaticity optics for the MAX IV 1.5 GeV storage ring and discusses performance limitations of the optics constrained by available gradient strength in the sextupoles.
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THPRO076	Frequency Maps Analysis of Tracking and Experimental Data for the SLS Storage Ring	3056
	P. Zisopoulos, F. Antoniou, Y. Papaphilippou CERN, Geneva, Switzerland A. Streun PSI, Villigen PSI, Switzerland V.G. Ziemann Uppsala University, Uppsala, Sweden
	Frequency Maps Analysis (FMA) has been widely used in beam dynamics in order to study dynamical aspects of the particles linear and non-linear motion, such as optics functions distortion, coupling, tune-shift and resonances. In this paper, FMA is employed to explore the dynamics of models of the Swiss Light Source (SLS) storage ring and compare them with measured turn by turn (TxT) position data. In particular, a method is proposed for estimating the momentum spread using synchrotron sidebands of the Fourier spectrum of the TxT data.
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THPRO079	Quantitative Analysis of Trapping Probability for Quasi-integrable Two-degree of Freedom Maps	3065
	M. Giovannozzi, C. Hernalsteens, J. Williams CERN, Geneva, Switzerland A. Bazzani Bologna University, Bologna, Italy C. Hernalsteens EPFL, Lausanne, Switzerland
	A key ingredient for the Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. In a previous paper a method allowing analytical estimation of the fraction of beam trapped into resonance islands as a function of the Hamiltonian parameters has been presented. Such a method applies to one-degree of freedom models of betatronic motion. In this paper, the analysis is extended to the more realistic and challenging case of two-degree of freedom systems, in which the interplay between the horizontal and vertical motion is fully included. Numerical simulations are presented and the results are discussed in detail.
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THPRO081	Simulation and Observation of Driven Beam Oscillations with Space Charge in the CERN PS Booster	3073
	M. McAteer, J.M. Belleman, E. Benedetto, C. Carli, A. Findlay, B. Mikulec, R. Tomás CERN, Geneva, Switzerland
	Funding: This project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme, contract number (PITN-GA-2011-289485-OPAC). As part of the LHC Injector Upgrade project, the CERN PS Booster will operate at higher injection and extraction energies and with nearly a factor of two increase in beam brightness. In order to better understand the machine’s limitations, a campaign of nonlinear optics measurements from turn-by-turn trajectory measurements is planned for after Long Shutdown 1. The goal of this work is to establish an efficient procedure for implementing a resonance compensation scheme after the machine’s injection energy is increased. The trajectory measurement system is expected initially to require high intensity beam in order to have good position measurement resolution, so understanding space charge effects will be important for optics analysis. We present the results of simulations of driven beam oscillations with space charge effects, and comparison with trial beam trajectory measurements.
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THPRO082	Observation of Coherent Instability in the CERN PS Booster	3076
	M. McAteer, C. Carli, V. Forte, G. Rumolo, R. Tomás CERN, Geneva, Switzerland
	Funding: This project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme, contract number (PITN-GA-2011-289485-OPAC). At high intensities and at a certain working point an instability develops in the CERN PS Booster, and large coherent transverse oscillations and beam loss occur. The coherent oscillations and beam loss can be effectively controlled with the transverse damper system, but the origin of the instability is not well-understood. Recent measurements with the PSB's new trajectory measurement system have provided some insight into the nature of this instability, and these observations are presented here.
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THPRO083	Weak-strong Beam-beam Simulations for HL-LHC	3079
	D. Banfi, J. Barranco García EPFL, Lausanne, Switzerland T. Pieloni CERN, Geneva, Switzerland A. Valishev Fermilab, Batavia, Illinois, USA
	In this paper we present dynamic aperture studies for possible High Luminosity LHC optics in the presence of beam-beam interactions, crab crossing schemes and magnets multipolar errors. Possible operational scenarios of luminosity leveling by transverse offset and betatron function are also studied and the impact on the beams stability is discussed.
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THPRO084	Beam Dynamics Observations of Slow Integer Tune Crossing in EMMA	3082
	J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	When the betatron tune is an integer in a cyclical accelerator, dipole-field errors can drive the coherent addition of betatron amplitude to the bunch eventually causing particle loss. Transverse integer tune crossing in a linear non-scaling FFAG is inevitable due to finite chromaticity. In EMMA (Electron Machine with Many Applications), as many as 6 integers may be crossed is as little as 6 turns at maximum acceleration over the 10 – 20 MeV energy range. This fast integer tune crossing, of the order 1 integer per turn, was shown to have little effect on the coherent amplitude growth and charge loss rate. Slower acceleration inside an RF bucket in EMMA allowed the experimental exploration of slower integer tune crossing speeds, of the order of a factor ten slower. The effect on the coherent oscillation amplitude was observed and the charge loss at integer tune crossings indicated resonant effects on the bunch. Simulations in Zgoubi allowed a more detailed analysis and the mechanism of slower resonance crossing in a non-scaling FFAG is discussed, including the importance of coupled longitudinal-transverse decoherence on the effective emittance.
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THPRO086	Flat-beam Generation and Compression at Fermilab's Advanced Superconducting Test Accelerator	3086
	J. Zhu, D. Mihalcea, P. Piot Fermilab, Batavia, Illinois, USA D. Mihalcea, P. Piot, C.R. Prokop Northern Illinois University, DeKalb, Illinois, USA
	An important asset of Fermilab’s Advanced Superconducting Test Accelerator (ASTA) is its ability to generate flat beams with high-transverse emittance ratios. In this paper, we present a practical design and simulation of flat beam generation and compression with various bunch charges up to 3.2 nC. Emittance growth within the round-to-flat beam transformer and the impact of low energy compression is discussed in detail. Finally, it is found that the compressed flat beam could provide exciting opportunities in the field of advanced acceleration techniques and accelerator-based light source.
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THPRO088	Optimization of the pp AGS Zgoubi Model in the Low Energy Range	3089
	Y. Dutheil, H. Huang, F. Méot, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. At low energy the AGS lattice is strongly deformed by the two strong helical snakes, required to preserve the polarization. In addition to the complex, highly non-linear field featured by the two snakes, multiple non-linear coupling resonance lines are crossed by the beam in this region. Hence, the use of realistic models for the Siberian snakes is critical for the simulation of the early part of the AGS acceleration cycle. The AGS Zgoubi model uses direct tracking through OPERA field maps of the two snakes. While many processes may be obnoxious to both beam and spin dynamics in this region, it is critical to use a realistic model of the AGS at low energy. This paper presents the current model used and some of the challenges recently faced. We will also compare experimental beam dynamics results to those predicted by the Zgoubi model.
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THPRO089	New Tune Jumps Scheme in the Low Energy Part of the AGS Cycle	3092
	Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, V. Schoefer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. During the early part of the acceleration of polarized protons, due to strong optical deformations of the lattice, the tune cannot be placed in the spin gap and the first two vertical intrinsic resonances are crossed. Recent multiparticle trackings using the Zgoubi code show that the spin resonances around Gg=5 could cause as much as 5% loss of polarization. The slow acceleration rate, the two vertical and two horizontal intrinsic spin resonances can contribute to the depolarization in the region. While in the current scheme only the two horizontal intrinsic resonances are jumped, it was proposed to use the tune jumps system to also accelerate the crossing of the two weak vertical intrinsic resonances and improve the polarization transmission through this region. We show the design of this new tune jumps scheme and the expected polarization gains expected from multiparticles Zgoubi simulations. We also compare experimental measurements of the polarization transmission to the Zgoubi simulations.
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THPRO090	Energy Calibration and Tune Jumps Efficiency in the pp AGS	3095
SUSPSNE052	use link to see paper's listing under its alternate paper code
	Y. Dutheil, L. Ahrens, H. Huang, F. Méot, A. Poblaguev, V. Schoefer, K. Yip BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The AGS tune jump system consists of two fast quadrupoles used to accelerate the crossing of 82 horizontal intrinsic spin resonances. The fast tune jump of ΔQh=+0.04 within 100 μs imposes perfect localization of each of the 82 resonant conditions. Imperfect timing of the tune jumps results in lower efficiency of the system and lower transmission of the polarization through the AGS acceleration cycle. Investigations during the end of the pp AGS Run13 revealed weaknesses in the energy measurement at high energy, causing less than optimal timing of the tune jumps. A new method based on continuous polarization measurement to determine the energy during the acceleration cycle has been developed. Strong operational constraints were taken into account to provide a convenient system of energy measurement. This is also used to calibrate the usual determination of the energy based on revolution frequency of the beam or measured dipole magnetic field. This paper shows the tools developed and the results of the first tests during the AGS Run 14. Simulations of the expected tune jumps efficiency using the AGS Zgoubi model are also presented and compared to experimental results.
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THPRO091	Strength of Horizontal Intrinsic Spin Resonances in the AGS	3098
	Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, T. Roser, V. Schoefer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Crossing of horizontal intrinsic resonances is today the main source of polarization losses in the AGS, in its dual partial snakes configuration for polarized proton acceleration. Polarization losses were greatly reduced by the AGS tune jump system. However total polarization transmission through the AGS cycle is not yet achieved, still partially due to the horizontal intrinsic resonances. This paper will explore the effect of optical distortions and different horizontal tunes on the strength of horizontal intrinsic resonances. Various options will be presented and practicability will be addressed. Theoretical model and multiparticle trackings using the Zgoubi code will show the expected polarization gains of different scenarios.
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THPME154	Turn-by-turn Beam Profile Study at VEPP-4M	3620
	O.I. Meshkov, E.B. Levichev, P.A. Piminov, A.N. Zhuravlev BINP SB RAS, Novosibirsk, Russia
	The beam dynamics during crossing of dynamical aperture border was studied. We controlled the beam losses and beam transversal profile during high-amplitude betatron oscillations caused by the electrostatic kick. The beam transversal profile was recorded by the Multi Anode Photomultiplier with turn-to turn temporal resolution. The experimental data are compared with numerical simulation.
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FRXAA01	Beam Dynamics Studies with Non-neutral Plasma Traps	4052
	H. Okamoto, K. Fukushima, H. Higaki, K. Ito, K. Moriya, T. Okano, K. Osaki HU/AdSM, Higashi-Hiroshima, Japan
	Both Paul ion traps and Penning traps have been employed at Hiroshima University to explore fundamental aspects of space-charge dominated beam dynamics. These compact accelerator-free experiments are based on an isomorphism between non-neutral plasmas in a trap and charged-particle beams traveling in a periodic focusing channel. This talk highlights the recent experimental results on coherent betatron resonances in various strong-focusing lattices, resonance crossing in non-scaling FFAG accelerators, ultra-low emittance beam stability, and halo formation.
	Slides FRXAA01 [5.557 MB]
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Paper

Title

Page

Bunch Compressor Design for CLIC Drive Beam

2924

A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
J. Esberg, D. Schulte
CERN, Geneva, Switzerland

The drive-beam linac which is required for generation RF power at Compact Linear Collider (CLIC) has to accelerate an electron beam with 8.4 nC per bunch up to 2.4 GeV in almost fully loaded structures. The required beam stability in both transverse and longitudinal directions are of concern for such a high bunch charge. We present different bunch compressor designs for the Drive Beam and compare their performance including the effects beam energy and phase jitters.

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THPRO055

Electron Beam Final Focus System for Thomson Scattering at ELBE

2995

J.M. Krämer, F. Bødker, A. Baurichter, M. Budde
Danfysik A/S, Taastrup, Denmark
A. Irman, U. Schramm
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
U. Lehnert, P. Michel
HZDR, Dresden, Germany

Funding: This work is part of LA3NET and funded by European Commission under Grant Agreement Number 289191.
The design of an electron beam Final Focus System (FFS) aiming for high-flux laser-Thomson backscattering x-ray sources at ELBE* is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole triplet. This allows sub-ps electron beam focusing to match the laser spot size at the interaction point. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. Since the electron beam is chirped for bunch compression upstream, the rms energy spread is increased to one or two percent and second order chromatic effects must be taken into account. For an emittance of 13 pi mm mrad, we predict rms spot sizes of about 40 um and divergences of about 15 mrad. We also present the design of the permanent magnet quadrupoles to be used for the FFS. Ferromagnetic poles ensure a high field quality and adjustable shunts allow for fine adjustment of the field strength and compensation of deviations in the permanent magnet material.
*A. Jochmann et al., Phys. Rev. Lett. 111 (2013) 114803

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THPRO056

Estimation of Systematic Errors for Deuteron Electric Dipole Moment (EDM) Search at a Storage Ring

2998

S. Chekmenev
RWTH, Aachen, Germany

An experimental method which is aimed to find a permanent EDM of a charged particle was proposed by JEDI (Jülich Electric Dipole moment Investigations) collaboration in 2012*. EDMs can be observed by their small influence on spin motion. The only possible way to perform a direct measurement is to use a storage ring. For this purpose it was decided to carry out the first precursor experiment at the Cooler Synchrotron (COSY). Since the EDM of a particle violates CP invariance and is expected to be tiny, treatment of all various sources of systematic errors should be done with a great level of precision. One should clearly understand how misalignments of the magnets affects the beam and the spin motion. In reality, one of the methods to investigate spin behavior in the presence of misalignments in a storage ring is to mimic their influence on the beam parameters using small orbit kicks with different amplitudes. In this talk the first simulations of orbit excitations will be discussed. The corresponding spin tune shifts will be considered. The influence of the distorted orbit on the polarization build-up caused by the EDM will be examined.
* A. Lehrach, F. Rathmann, J. Pretz et al., "Search for Permanent Electric Dipole Moments at COSY. Step 1: Spin coherence and systematic error studies", 2012

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THPRO057

Advanced Magnetic Field Description and Measurements on Curved Accelerator Magnets

3002

P. Schnizer, E.S. Fischer, A. Mierau
GSI, Darmstadt, Germany
P.G. Akishin
JINR, Dubna, Moscow Region, Russia
B. Schnizer
TUG/ITP, Graz, Austria

The SIS100 accelerator will be built within the first realisation phase of the FAIR project. The series production of its superconducting bending magnets was started without any test model in 2013. This time saving strategy requires a careful investigation of the magnetic field quality for the first manufactured dipole. The consequences of the curved magnet design was analysed developing advanced multipoles for elliptical and toroidal magnet geometries. We present the theoretical results together with measured data obtained for the first of series dipole. A description of the rotating coil probe based measurement method will be given together with the achieved field quality as well as an estimation of the limits of the chosen field representation and its beam dynamics interpretation.

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THPRO058

Study of the “Particle-in-Cell” Induced Noise on High Intensity Beams

3005

SUSPSNE055

use link to see paper's listing under its alternate paper code

F. Kesting, G. Franchetti
GSI, Darmstadt, Germany
U. Ratzinger
IAP, Frankfurt am Main, Germany

Numerical noise in PIC codes produces artifacts which affects long term beam simulations needed for accelerator as the SIS100. A detailed study on the effect of numerical noise occurring in multi-particle tracking codes is presented. The influence of the granularity of particle distributions and the fineness of the meshes of Poisson solvers on the particle dynamics was studied. These results are used to discuss the effect of the PIC numerical noise in a long term space charge benchmarking study.

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THPRO059

Simulation Study on Beam Loss in the Alpha Bucket Regime during SIS-100 Proton Operation

3008

S. Sorge
GSI, Darmstadt, Germany

Besides heavy ion operation, the heavy ion synchrotron SIS-100 will accelerate a single proton bunch of N=2*10¹³ particles up to the energy E=29 GeV. For the present standard scenario, optics settings have been developed which provide a transition energy according to gamma_tr=45.5 in order to avoid transition crossing during acceleration. At extraction energy the corresponding nonlinear momentum compaction and phase slip factors cause the formation of a so called alpha bucket. In this contribution we present the results of transverse beam loss tracking studies in the alpha bucket regime. The effects of momentum spread, magnet errors and residual closed orbit distortion are analyzed.

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THPRO060

Beam-beam Effect on the BTF in Bunched Beams

3011

SUSPSNE053

use link to see paper's listing under its alternate paper code

P.A. Görgen, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
W. Fischer
BNL, Upton, Long Island, New York, USA

We present studies on the transverse baseband Beam Transfer Functions (BTFs) in bunched beams at high energies. The goal of the work is to evaluate whether transverse BTFs can be used to diagnose the tune spread arising from transverse nonlinearities such as the beam-beam effect and space charge. We employ an analytic expression to the BTFs of beams under a transverse nonlinear lens arising from a bi-Gaussian charge distribution. We obtain agreement between a simulation model of an electron-lens like configuration and the analytic results. The tune spread for this scenario can be recovered by means of a fit against the analytic expectation. The results are compared with measurements where the beam-beam effect acts as a substitute for the electron lens. A similar behaviour of the BTF is observed. This allows the conclusion that the transverse BTF can be used to diagnose tune spread from an electron-lens. Finally we discuss the problems that arise when trying to recover the tune spread from BTFs of arbitrary non-Gaussian beams and in the presence of coherent beam-beam modes.

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THPRO061

New and Unifying Formalism for Study of Particle-Spin Dynamics Using Tools Distilled From Theory of Bundles

3014

K.A. Heinemann, J.A. Ellison
UNM, Albuquerque, New Mexico, USA
D.P. Barber
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.P. Barber, M. Vogt
DESY, Hamburg, Germany

Funding: The work of JAE and KH was supported by DOE under DE-FG-99ER41104 and the work of DPB and MV was supported by DESY.
We summarize our recent work on spin motion in storage rings *. In fact we return to our study ** of spin motion in storage rings. We again focus on spin tunes, polarization fields etc. but in contrast to ** we base the description on one turn maps and refine and expand our toolset from that in * by using a rather modern method from Dynamical-Systems theory, developed in the 1980's by R. Zimmer and others based on bundles **, ***. With this we obtain new insights into invariant spin fields, invariant frame fields, spin tunes and spin-orbit resonances. At the same time we get a unified way to treat spin-1/2 and spin-1 particles. The bundle aspect is pointed out and we briefly mention the relation to Yang-Mills Theory as well.
* K.Heinemann, D.P.Barber, J.A.Ellison, M.Vogt. To be submitted.
** D.P.B., J.A.E., K.H., PRSTAB 7 (2004) 124002.
*** K.Heinemann, PhD Thesis, University of New Mexico, 2010 (available on the web).

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THPRO062

Spin Tune Decoherence in Multipole Fields

3017

Y. Senichev, A.N. Ivanov, A. Lehrach, R. Maier, D. Zyuzin
FZJ, Jülich, Germany
S.N. Andrianov
St. Petersburg State University, St. Petersburg, Russia

This article analyzes possible limitations in the method to search for the electric dipole moment (EDM) using polarized particles in a storage ring. It is well known that for detection of the electric dipole moment one needs to create such conditions where the particle's spin oscillations can be caused only by the EDM. Really, there are two possible methods for EDM search using a storage ring: resonant spin buildup in a magnetostatic ring and “frozen” spin method in an electrostatic ring with “magic” energy. Both methods have common limitations caused by spin decoherence. In the frame of self consistent theory the reasons of the spin decoherence are classified independently on method and discussed taking into consideration multipole components of external fields, as well as the nonlinearities of RF fields.

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THPRO063

Spin Tune Parametric Resonance Investigation

3020

Y. Senichev, A.N. Ivanov, A. Lehrach, R. Maier, D. Zyuzin
FZJ, Jülich, Germany
S.N. Andrianov
St. Petersburg State University, St. Petersburg, Russia

The idea of resonant spin oscillation method was modernized and improved in Forschungszentrum Julich in the proposed experiment at the COSY ring. The resonant method is based on spin tune parameterization using transverse RF magnetic or/and electric field. The spin orientation smearing due to the finite spin coherence time (SCT) plays a crucial in the proposed experiment to search for the electric dipole moment. Our analysis is based on the T-BMT differential equations for spin together with shorten motion equations. Using well developed theory of Mathieu's differential equations we have got simplified analytic solution for prediction of spin behavior. In this paper we have numerically evaluated all effects having fundamental contributions from our point of view.

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THPRO064

Effect of Laser-plasma Channeling on Third-harmonic Radiation Generation

3023

M. Singh, D.N. Gupta
University of Delhi, Delhi, India

An intense Gaussian laser beam, propagating through a magnetized plasma, becomes self-focused due to the ponderomotive force on the electrons. The magnetic field reduces the radius of the laser beam and enhances the self focusing of the laser beam. The self-sustained plasma channel can affect the efficiency of harmonic generation of the interacting laser beam. The radial density gradient of the channel beats with the oscillatory electron velocity to produce density perturbation at laser frequency. The ponderomotive force at second-harmonic frequency produces electrons density oscillations that beat with the oscillatory velocity to create a non-linear current, driving the third harmonic radiation. The velocity and density perturbation associated with the self-focused laser beam generates a nonlinear current at triple fold frequency of the fundamental laser. Our results show that the efficiency of third-harmonic generation of the laser beam is affected significantly due to the self-sustained plasma channel. The strength of magnetic field play a crucial role in efficiency enhancement of third-harmonic generation.

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THPRO065

De-coherence Study of Betatron Oscillation for the Beam Shape Manipulation

3026

Y. Shoji
LASTI, Hyogo, Japan

In electron storage ring a temporal perturbation to the beam makes spatial structure in a bunch, which emit short X-ray or coherent THz radiation. For this technique of bunch shape manipulation, it is important to reduce unwanted de-coherence of betatron motion, which would break the intended spatial structure. At NewSUBARU, 1.5 GeV storage ring, we kicked the beam using a vertical fast kicker and investigated the de-coherence of betetron oscillation using mainly a dual-sweep streak camera. The largest is the Landau damping by a well-known chromatic tune spread, although the phase spread comes back to zero at after a synchrotron oscillation period. On the other hand, there exists several non-linear effects, which makes accumulation of the oscillation phase spread. These are, horizontal betatron amplitude dependent vertical tune shift, synchrotron oscillation amplitude dependent synchrotron tune shift, non-linear chromaticity, synchrotron oscillation chromaticity (non-symmetry of rf bucket), longitudinal radiation excitation process, and others. The tuning knobs we had was some sets of non-linear magnets up to octupole and the rf voltage.

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THPRO066

Correction of the Higher Order Dispersion for Improving Momentum Acceptance

3029

M. Takao, K.K. Kaneki, Y. Shimosaki, K. Soutome
JASRI/SPring-8, Hyogo-ken, Japan

May 2013 we lowered the emittance of the SPring-8 storage ring from 3.5 nm¥cdotrad to 2.4 nm¥cdotrad to enhance the brilliance. At the optics change the momentum acceptance shrunk from 3.2 ¥% to 2.4 ¥%. Then, by carefully correcting the second order dispersion, we recovered the momentum acceptance up to 2.8 ¥%, which results in doubling the Touschek beam lifetime. Although the injection efficiency decreased by more than 10 ¥% by the dispersion correction, we restored it by means of suppressing the amplitude dependent tune shift. Here we describe these improvements of the nonlinear dynamics of the SPring-8 storage ring.

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THPRO067

Modeling Slow Extraction Process For J-PARC Main Ring

3032

A.Y. Molodozhentsev
KEK, Ibaraki, Japan

J-PARC Main Ring has to deliver the proton beam to ‘hadron’ experiments by using ‘slow extraction’ technique, base on the 3rd order horizontal resonance. The spill quality during the full extraction period is one of the most important requirements as well as the beam quality. The computer modeling of the slow extraction process for J-PARC Main Ring is based on a realistic machine model, which includes measured imperfections of the machine in addition to dynamic variation of the machine elements to perform the slow extraction. In frame of this report we represent the results of the modeling the slow extraction process from J-PARC Main Ring by using the PTC-ORBIT combined code. The resonance extraction has been controlled by changing the betatron tune. Control the horizontal emittance of the extracted beam has been performed by using ‘dynamic’ bumps. Control the spill quality of the extracted beam has been performed by using dedicated quadrupole magnets and the transverse RF signal (RF knockout). In addition, the spill quality can be improved by suppressing effect of the power supply ripple. On the request, the collective effects can be introduced into the model.

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THPRO068

Multipoles and Alignment Error Limits for the SESAME Storage Ring Magnets

3035

M. Attal, E. Huttel
SESAME, Allan, Jordan

SESAME storage ring magnets are being constructed through the CESSAMag project in the frame of SESAME - CERN/EU collaboration. The impact of multipole and alignment errors of these magnets on machine performance have been investigated using different tracking codes. The tolerance of both systematic and random errors are defined. This article reports on the investigation results.

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THPRO070

Beam Dynamics Simulations in Cyclotron C230 Considering Imperfections of Magnetic Field Radial Component

3038

E. Samsonov, S.A. Kostromin, N.A. Morozov, E. Syresin
JINR, Dubna, Moscow Region, Russia

Simulations concern to a beam axial motion in the IBA cyclotron C230 that is a base facility in several medical centers worldwide. Because of small axial focusing of the beam in a center of the cyclotron the radial component of magnetic field imperfections leads to additional proton losses. Measured maps of the axial and radial components of magnetic field were used in the simulations. It was found that the radial component with value 5-10 G in the center and approximately 2 G in the main region of acceleration leads to decrease of the resulting beam intensity by about two times and to increase the beam axial width by 25% as well. Simulations define the requirements to the experimental radial component shaping for the next cyclotrons of this series. Providing these requirements will ensure an absence of the additional proton losses due to the axial motion perturbations.

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THPRO071

Control of Calculations in the Beam Dynamics using Approximate Invariants

3041

S.N. Andrianov
St. Petersburg State University, St. Petersburg, Russia
D. Zyuzin
FZJ, Jülich, Germany

One of the important problems in the theory of dynamical systems is to find corresponding (invariants). In this article we are discussing some problems of computing of invariant functions (invariants) for dynamical systems. These invariants can be used for describing of particle beams systems. The suggested method is constructive and based on the matrix formalism for Lie algebraic tools. We discuss two types of invariants: kinematic and dynamic. All calculations can be realized in symbolic forms, in particular, kinematic invariants are based on the theory of representations of Lie algebras (in particular, using the Casimir’s operators). For the case of nonlinear kinematic invariants we propose a recursive scheme, which can be implemented in symbolic forms using instruments of computer algebra (for example, such packages as Maple or Mathematica). The corresponding expressions for invariants can be used to control the correctness of computational experiments, first of all for long time beam dynamics.

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THPRO072

Field Parametrisation for the ESS Superconducting Cavities

3044

T. Lindqvist
Lund University, Lund, Sweden
E. Laface
ESS, Lund, Sweden

Here we present a method for constructing a parametrization of the electric field in the superconducting elliptic cavities of the ESS linac. The parametrization is done by replicating the electric field from measured data using trigonometric and exponential functions. The field generated by the parameters exhibits a mean error of 0.28% ( maximum error of 3.8% and s.t.d. error 1.1%), with the advantage of only taking up a fraction of the required data. The field in the entire cavity is extrapolated by combining the Maxwell equations with the parametrized form of the field. We also present particle simulations based on the parametrization model to showcase some typical accelerator behaviour. Additionally we present a small extension of the parametrization method to also model spoke cavities.

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THPRO073

Longitudinal Acceptance Evaluation from Hamiltonian

3047

E. Laface
ESS, Lund, Sweden

An RF cavity is designed around a reference particle; if the energy or the phase of a real particle are too far from the reference, the particle is lost. The widest area of energy-phase that allows a particle to be transported by the cavity is called acceptance of the cavity. In simulations the acceptance is evaluated tracking several particles with different energies and phases and marking when a particle is transmitted or lost. This process can be time consuming because of the large amount of tracked particles requested to characterise the cavity acceptance. In this paper we propose an alternative method to evaluate the acceptance studying directly the Hamiltonian associated to the cavity.

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THPRO074

Characterization of the Longitudinal Wakefields in the MAX IV Linac

3050

SUSPSNE054

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O. Karlberg, F. Curbis, S. Thorin, S. Werin
MAX-lab, Lund, Sweden

In the second part of 2014, the 3GeV linac at the MAX IV laboratory will enter its commissioning stage. Equipped with two guns, the linac will act as a full energy injector for the two storage rings and at the same time provide high brightness pulses to a Short Pulse Facility (SPF). Compression in the linac is done in two double achromats with fixed R56 that relies upon the RF phase introduced energy chirp, which in this case is strongly enhanced by the longitudinal wakefields. Since the longitudinal wakefields plays a major role in the compression and bunch shaping they need to be carefully investigated during the commissioning. In this proceeding we will discuss a measurement technique that will be used during commissioning to characterize the longitudinal wakefields and their precise effects on e.g. the bunch shape and the energy spread. Predictions obtained from particle tracking will be presented.

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THPRO075

High-chromaticity Optics for the MAX IV 1.5 GeV Storage Ring

3053

SUSPSNE056

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T. Olsson, S.C. Leemann
MAX-lab, Lund, Sweden

The MAX IV facility currently under construction in Lund, Sweden will include a 1.5 GeV storage ring. To prevent head-tail instability, the negative natural chromaticities of the MAX IV 1.5 GeV storage ring have been corrected to positive values using sextupole gradients in the focusing quadrupoles along with dedicated sextupole magnets. To allow adjustment of the chromaticity correction, weak correction sextupoles have been inserted into the lattice. A high-chromaticity optics has been developed for the MAX IV 1.5 GeV storage ring in case instability issues arise during commissioning. Two chromatic sextupole families were used to correct the linear chromaticity. The tune footprint was then tailored using the remaining two sextupole families with the goal of maximizing dynamic aperture and Touschek lifetime. This paper describes the recently developed high-chromaticity optics for the MAX IV 1.5 GeV storage ring and discusses performance limitations of the optics constrained by available gradient strength in the sextupoles.

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THPRO076

Frequency Maps Analysis of Tracking and Experimental Data for the SLS Storage Ring

3056

P. Zisopoulos, F. Antoniou, Y. Papaphilippou
CERN, Geneva, Switzerland
A. Streun
PSI, Villigen PSI, Switzerland
V.G. Ziemann
Uppsala University, Uppsala, Sweden

Frequency Maps Analysis (FMA) has been widely used in beam dynamics in order to study dynamical aspects of the particles linear and non-linear motion, such as optics functions distortion, coupling, tune-shift and resonances. In this paper, FMA is employed to explore the dynamics of models of the Swiss Light Source (SLS) storage ring and compare them with measured turn by turn (TxT) position data. In particular, a method is proposed for estimating the momentum spread using synchrotron sidebands of the Fourier spectrum of the TxT data.

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THPRO079

Quantitative Analysis of Trapping Probability for Quasi-integrable Two-degree of Freedom Maps

3065

M. Giovannozzi, C. Hernalsteens, J. Williams
CERN, Geneva, Switzerland
A. Bazzani
Bologna University, Bologna, Italy
C. Hernalsteens
EPFL, Lausanne, Switzerland

A key ingredient for the Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. In a previous paper a method allowing analytical estimation of the fraction of beam trapped into resonance islands as a function of the Hamiltonian parameters has been presented. Such a method applies to one-degree of freedom models of betatronic motion. In this paper, the analysis is extended to the more realistic and challenging case of two-degree of freedom systems, in which the interplay between the horizontal and vertical motion is fully included. Numerical simulations are presented and the results are discussed in detail.

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THPRO081

Simulation and Observation of Driven Beam Oscillations with Space Charge in the CERN PS Booster

3073

M. McAteer, J.M. Belleman, E. Benedetto, C. Carli, A. Findlay, B. Mikulec, R. Tomás
CERN, Geneva, Switzerland

Funding: This project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme, contract number (PITN-GA-2011-289485-OPAC).
As part of the LHC Injector Upgrade project, the CERN PS Booster will operate at higher injection and extraction energies and with nearly a factor of two increase in beam brightness. In order to better understand the machine’s limitations, a campaign of nonlinear optics measurements from turn-by-turn trajectory measurements is planned for after Long Shutdown 1. The goal of this work is to establish an efficient procedure for implementing a resonance compensation scheme after the machine’s injection energy is increased. The trajectory measurement system is expected initially to require high intensity beam in order to have good position measurement resolution, so understanding space charge effects will be important for optics analysis. We present the results of simulations of driven beam oscillations with space charge effects, and comparison with trial beam trajectory measurements.

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THPRO082

Observation of Coherent Instability in the CERN PS Booster

3076

M. McAteer, C. Carli, V. Forte, G. Rumolo, R. Tomás
CERN, Geneva, Switzerland

Funding: This project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme, contract number (PITN-GA-2011-289485-OPAC).
At high intensities and at a certain working point an instability develops in the CERN PS Booster, and large coherent transverse oscillations and beam loss occur. The coherent oscillations and beam loss can be effectively controlled with the transverse damper system, but the origin of the instability is not well-understood. Recent measurements with the PSB's new trajectory measurement system have provided some insight into the nature of this instability, and these observations are presented here.

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THPRO083

Weak-strong Beam-beam Simulations for HL-LHC

3079

D. Banfi, J. Barranco García
EPFL, Lausanne, Switzerland
T. Pieloni
CERN, Geneva, Switzerland
A. Valishev
Fermilab, Batavia, Illinois, USA

In this paper we present dynamic aperture studies for possible High Luminosity LHC optics in the presence of beam-beam interactions, crab crossing schemes and magnets multipolar errors. Possible operational scenarios of luminosity leveling by transverse offset and betatron function are also studied and the impact on the beams stability is discussed.

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THPRO084

Beam Dynamics Observations of Slow Integer Tune Crossing in EMMA

3082

J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

When the betatron tune is an integer in a cyclical accelerator, dipole-field errors can drive the coherent addition of betatron amplitude to the bunch eventually causing particle loss. Transverse integer tune crossing in a linear non-scaling FFAG is inevitable due to finite chromaticity. In EMMA (Electron Machine with Many Applications), as many as 6 integers may be crossed is as little as 6 turns at maximum acceleration over the 10 – 20 MeV energy range. This fast integer tune crossing, of the order 1 integer per turn, was shown to have little effect on the coherent amplitude growth and charge loss rate. Slower acceleration inside an RF bucket in EMMA allowed the experimental exploration of slower integer tune crossing speeds, of the order of a factor ten slower. The effect on the coherent oscillation amplitude was observed and the charge loss at integer tune crossings indicated resonant effects on the bunch. Simulations in Zgoubi allowed a more detailed analysis and the mechanism of slower resonance crossing in a non-scaling FFAG is discussed, including the importance of coupled longitudinal-transverse decoherence on the effective emittance.

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THPRO086

Flat-beam Generation and Compression at Fermilab's Advanced Superconducting Test Accelerator

3086

J. Zhu, D. Mihalcea, P. Piot
Fermilab, Batavia, Illinois, USA
D. Mihalcea, P. Piot, C.R. Prokop
Northern Illinois University, DeKalb, Illinois, USA

An important asset of Fermilab’s Advanced Superconducting Test Accelerator (ASTA) is its ability to generate flat beams with high-transverse emittance ratios. In this paper, we present a practical design and simulation of flat beam generation and compression with various bunch charges up to 3.2 nC. Emittance growth within the round-to-flat beam transformer and the impact of low energy compression is discussed in detail. Finally, it is found that the compressed flat beam could provide exciting opportunities in the field of advanced acceleration techniques and accelerator-based light source.

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THPRO088

Optimization of the pp AGS Zgoubi Model in the Low Energy Range

3089

Y. Dutheil, H. Huang, F. Méot, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
At low energy the AGS lattice is strongly deformed by the two strong helical snakes, required to preserve the polarization. In addition to the complex, highly non-linear field featured by the two snakes, multiple non-linear coupling resonance lines are crossed by the beam in this region. Hence, the use of realistic models for the Siberian snakes is critical for the simulation of the early part of the AGS acceleration cycle. The AGS Zgoubi model uses direct tracking through OPERA field maps of the two snakes. While many processes may be obnoxious to both beam and spin dynamics in this region, it is critical to use a realistic model of the AGS at low energy. This paper presents the current model used and some of the challenges recently faced. We will also compare experimental beam dynamics results to those predicted by the Zgoubi model.

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THPRO089

New Tune Jumps Scheme in the Low Energy Part of the AGS Cycle

3092

Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, V. Schoefer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
During the early part of the acceleration of polarized protons, due to strong optical deformations of the lattice, the tune cannot be placed in the spin gap and the first two vertical intrinsic resonances are crossed. Recent multiparticle trackings using the Zgoubi code show that the spin resonances around Gg=5 could cause as much as 5% loss of polarization. The slow acceleration rate, the two vertical and two horizontal intrinsic spin resonances can contribute to the depolarization in the region. While in the current scheme only the two horizontal intrinsic resonances are jumped, it was proposed to use the tune jumps system to also accelerate the crossing of the two weak vertical intrinsic resonances and improve the polarization transmission through this region. We show the design of this new tune jumps scheme and the expected polarization gains expected from multiparticles Zgoubi simulations. We also compare experimental measurements of the polarization transmission to the Zgoubi simulations.

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THPRO090

Energy Calibration and Tune Jumps Efficiency in the pp AGS

3095

SUSPSNE052

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Y. Dutheil, L. Ahrens, H. Huang, F. Méot, A. Poblaguev, V. Schoefer, K. Yip
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The AGS tune jump system consists of two fast quadrupoles used to accelerate the crossing of 82 horizontal intrinsic spin resonances. The fast tune jump of ΔQh=+0.04 within 100 μs imposes perfect localization of each of the 82 resonant conditions. Imperfect timing of the tune jumps results in lower efficiency of the system and lower transmission of the polarization through the AGS acceleration cycle. Investigations during the end of the pp AGS Run13 revealed weaknesses in the energy measurement at high energy, causing less than optimal timing of the tune jumps. A new method based on continuous polarization measurement to determine the energy during the acceleration cycle has been developed. Strong operational constraints were taken into account to provide a convenient system of energy measurement. This is also used to calibrate the usual determination of the energy based on revolution frequency of the beam or measured dipole magnetic field. This paper shows the tools developed and the results of the first tests during the AGS Run 14. Simulations of the expected tune jumps efficiency using the AGS Zgoubi model are also presented and compared to experimental results.

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THPRO091

Strength of Horizontal Intrinsic Spin Resonances in the AGS

3098

Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, T. Roser, V. Schoefer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Crossing of horizontal intrinsic resonances is today the main source of polarization losses in the AGS, in its dual partial snakes configuration for polarized proton acceleration. Polarization losses were greatly reduced by the AGS tune jump system. However total polarization transmission through the AGS cycle is not yet achieved, still partially due to the horizontal intrinsic resonances. This paper will explore the effect of optical distortions and different horizontal tunes on the strength of horizontal intrinsic resonances. Various options will be presented and practicability will be addressed. Theoretical model and multiparticle trackings using the Zgoubi code will show the expected polarization gains of different scenarios.

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THPME154

Turn-by-turn Beam Profile Study at VEPP-4M

3620

O.I. Meshkov, E.B. Levichev, P.A. Piminov, A.N. Zhuravlev
BINP SB RAS, Novosibirsk, Russia

The beam dynamics during crossing of dynamical aperture border was studied. We controlled the beam losses and beam transversal profile during high-amplitude betatron oscillations caused by the electrostatic kick. The beam transversal profile was recorded by the Multi Anode Photomultiplier with turn-to turn temporal resolution. The experimental data are compared with numerical simulation.

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FRXAA01

Beam Dynamics Studies with Non-neutral Plasma Traps

4052

H. Okamoto, K. Fukushima, H. Higaki, K. Ito, K. Moriya, T. Okano, K. Osaki
HU/AdSM, Higashi-Hiroshima, Japan

Both Paul ion traps and Penning traps have been employed at Hiroshima University to explore fundamental aspects of space-charge dominated beam dynamics. These compact accelerator-free experiments are based on an isomorphism between non-neutral plasmas in a trap and charged-particle beams traveling in a periodic focusing channel. This talk highlights the recent experimental results on coherent betatron resonances in various strong-focusing lattices, resonance crossing in non-scaling FFAG accelerators, ultra-low emittance beam stability, and halo formation.

Slides FRXAA01 [5.557 MB]

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