Paper  Title  Page 

TPAT001  An UltraBright Pulsed Electron Beam with Low Longitudinal Emittance  770 


Funding: Work supported by the U.S. Department of Energy under Contract No. DEAC0376SF00098. We describe a novel scheme for an electron source in the 10  100 eV range with the capability of approaching the brightness quantumlimit and of lowering the effective temperature of the electrons orders of magnitude with respect to existing sources. Such a device can open the way for a wide range of novel applications that utilize angstromscale spatial resolution and ?eVscale energy resolution. Possible examples include electron microscopy, electron holography, and investigations of dynamics on a picosecond time scale using pumpprobe techniques. In this paper we describe the concepts for such a source including a complete and consistent set of parameters for the construction of a real device based on the presented scheme. 

TPAT002  ThreeDimensional Simulation of LargeAspectRatio EllipseShaped ChargedParticle Beam Propagation  823 


Funding: U.S. Department of Energy: Grant No. DEFG0295ER40919, Grant No. DEFG0201ER54662, Air Force Office of Scientific Research: Grant No. F496200310230, and the MIT Deshpande Center for Technological Innovation. The threedimensional trajectory code, OMNITRAK, is used to simulate a spacechargedominated beam of largeaspectratio elliptic crosssection propagating in a nonaxisymmetric periodic permanent magnet focusing field. The simulation results confirm theoretical predictions in the paraxial limit. A realistic magnetic field profile is applied, and the beam sensitivity to magnet nonlinearities and misalignments is studied. The imagecharge effect of conductor walls is examined for a variety of beam tunnel sizes and geometries. 

TPAT003  ColdFluid Equilibrium of a LargeAspectRatio EllipseShaped ChargedParticle Beam in a NonAxisymmetric Periodic Permanent Magnet Focusing Field  853 


Funding: U.S. DOE, Grant: No. DEFG0295ER40919,Grant No. DEFG0201ER54662, Air Force Office of Scientific Research, Grant No. F496200310230, and the MIT Deshpande Center for Technological Innovation. A new class of equilibrium is discovered for a largeaspectratio ellipseshaped chargedparticle beam in a nonaxisymmetric periodic permanent magnet focusing field. A paraxial coldfluid model is employed to derive the equilibrium flow properties and generalized envelope equations with negligibly small emittance. A periodic beam equilibrium solution is obtained numerically from the generalized envelope equations. It is shown that the beam edges are well confined in both transverse directions, and that the equilibrium beam exhibits a smallangle periodic wobble as it propagates. A twodimensional particleincell (PIC) code, PFB2D, is used to verify the theoretical predictions in the paraxial limit, and to establish validity under nonparaxial situations and the influence of the conductor walls of the beam tunnel. 

TPAT004  Strongly Asymmetric Beams at the University of Maryland Electron Ring (UMER)  892 


Funding: This work is funded by U.S. Dept. of Energy under grants DEFG0294ER40855 and DEFG0292ER54178. The standard operation of the University of Maryland electron ring employs symmetric strong focusing with magnetic quadrupoles, i.e., a FODO scheme whereby the zerocurrent betatron phase advances per period in the two transverse planes are equal or nearly so. Asymmetric focusing, on the other hand, employs quadrupoles with different strengths in a FODO cell. Typically, a small focusing asymmetry is implemented in most accelerators to set the operating point (horizontal and vertical zerocurrent tunes) in order to avoid resonances and/or compensate for edge focusing of bend magnets. Extreme asymmetry, however, is rarely, if at all, used. We review the motivation and theory of beam transport with general focusing asymmetry. We also present results of preliminary experiments and simulations with highly asymmetric focusing of a spacecharge dominated electron beam in UMER. 

TPAT005  Start to End Error Study for the SPIRAL2 Linac  934 


Funding: CEA The possibility of a high intensity accelerator at GANIL, producing secondary beams of unprecedented intensity, is considered. The proposed driver for the SPIRAL2 project aims to accelerate a 5 mA deuteron beam up to 20 A.MeV and a 1 mA ion beam for q/A = 1/3 up to 14.5 A.MeV. It is a continuous wave regime linac, designed for a maximum efficiency in the transmission of intense beams and a tunable energy. This paper presents the error sensitivity study which has been performed for this linac in order to define the tolerances for the construction. The correction scheme and the expected losses are described. 

TPAT006  Impact of Optics on CSRRelated Emittance Growth in Bunch Compressor Chicanes  1015 


The dependence of emittance growth due to Coherent Synchrotron Radiation (CSR) in bunch compressor chicanes on optics has been noticed and empirically studied in the past. We revisit the subject, suggesting a model to explain slice emittance growth dependence on chicane optics. A simplified model to calculate projected emittance growth when it is mainly caused by transverse slice centroid offsets is presented. It is then used to find optimal compensation of centroid kicks in the single chicanes of a twostage compression system by adjusting the phase advance of the transport in between and the ration of the compression factors.  
TPAT007  RF Defocusing in SuperConducting Structure with Constant Geometry  1042 


Due to higher accelerating gradient in the superconducting linac the RF defocusing factor plays significant role in the beam dynamics. Together with the space charge it is a main reason for the stability loss. Usually it is estimated in frame of the travelling wave formalism with synchronous motion. However, the superconducting cavity is desirable to have the constant geometry, when synchronous motion is absent. In this case the quasisynchronous phase velocity is adjusted by RF phasing. In this paper we investigate RF defocusing factor in absent of synchronism between the beam and the accelerating structure.  
TPAT008  Numerical Dispersion Error Reduction in EM Calculations for Accelerators  1114 


Funding: Deutsches ElektronenSynchrotron DESY In this contribution novel numerical algorithms with no dispersion along the beam axis are investigated. This property is of interest for the longtime calculation of electromagnetic fields in accelerators. Instead of increasing the spatial stencil of the Yee scheme the compared methods modify the timestepping algorithm.The results are compared on several test examples. As a practical application the electromagnetic field of a very short bunch inside a cavity is calculated. 

TPAT010  Practical Definitions of Beam Lifetimes in an Electron Storage Ring  1216 


Derived are simple definitions of beam lifetimes in an electron storage ring. They are defined in terms of measured beam lifetime and its time derivative. They are practical rather than theoretical. The only condition required is suppression or saturation of the radiative polarization.  
TPAT011  Impedance Analysis of Longitudinal Bunch Shape Measurements at PLS  


We measured the longitudinal bunch shape by streak camera at 2.5 GeV Pohang Light Source. The impedances estimated by a series R+L model indicate a resistance R= 960 ohm, an inductance L= 80 nH and a longitudinal impedance Z/n= 0.53 ohm. The scaling law for the bunch lengthenig is expressed as I^{0}.22. The effects of insertion device in the ring on the ring impedance, particularly the vertical height of invacuum undulator are also presented.  
TPAT014  A Novel Technique for Multiturn Injection in a Circular Accelerator Using Stable Islands in Transverse Phase Space  1377 


By applying a timereversal to the multiturn extraction recently proposed a novel approach to perform multiturn injection is proposed. It is based on the use of stable islands of the horizontal phase space generated by means of sextupoles and octupoles. A particle beam can be injected into stable islands of phase space, and then a slow tune variation allows merging the beam trapped inside the islands. The results of numerical simulations will be presented and discussed in details, showing how to use the proposed approach to generate hollow bunches.  
TPAT015  Simulations of ErrorInduced Beam Degradation in Fermilab's Booster Synchrotron  1458 


Funding: Work supported by the University Research Association, Inc. under U.S. Department of Energy (DOE) contract No. DEAC0276CH03000, and by DOE grant No. DEFG0204ER41323 to NIU, and by DOE grant No. DEFG0291ER40685 to University of Rochester. Individual particle orbits in a beam will respond to both external focusing and accelerating forces as well as internal spacecharge forces. The external forces will reflect unavoidable systematic and random machine errors, or imperfections, such as jitter in magnet and radiofrequency power supplies, as well as magnet translation and rotation alignment errors. The beam responds in a selfconsistent fashion to these errors; they continually do work on the beam and thereby act as a constant source of energy input. Consequently, halo formation and emittnace growth can be induced, resulting in beam degradation and loss. We have upgraded the ORBITFNAL package and used it to compute effects of machine errors on emittance dilution and halo formation in the existing FNALBooster synchrotron. This package can be applied to study other synchrotrons and storage rings, as well. 

TPAT017  Transverse Impedance of Elliptical Tapers  1535 


Funding: Work supported by the U.S. DOE. The geometric impedance of smallgap undulator chambers is of paramount importance for modern light sources because it may drive transverse single bunch instabilities. Analytical expressions are derived for the transverse impedance assuming a slowly tapered vacuum chamber with a confocal elliptical crosssection. The analytical results are confirmed by numerical simulations with the GdfidL Electromagnetic Field simulator and they yield the correct asymptotic limits for both round and flat chambers. 

TPAT018  Stability of Barrier Buckets with Short or Zero Barrier Separations  1589 


A barrier bucket with small separation between the rf barriers (relative to the barrier widths) or even zero separation has its synchrotron tune decreasing rather slowly towards the boundary of the bucket. As a result, large area at the bucket edges can become unstable under the modulation of rf voltage and rf phase. Application is made to those barrier buckets used in the process of momentum mining on the issues of bunchdistribution distortion and particle loss.  
TPAT019  Discussions on the Cancellation Effect on a Curved Orbit  1631 


Funding: Work supported by DOE Contract DEAC0584ER40150.
The canonical formulation and the cancellation effect for bunch dynamics under collective interaction on a curved orbit were presented in Ref. [*]. Some possible controversial representations of the cancellation effect were later addressed by Geloni et al.** In this study, we discuss all the points raised in Ref. [**] based on our canonical treatment, and show how these points can be perceived from the view point of the cancellation picture.
*R. Li and Ya. S. Derbenev, Jefferson Laboratory Report No. LJABTN02054, 2003. **G. Geloni et al., DESY Report No. DESY 03165, 2003. 

TPAT022  Future Plans for the Small Isochronous Ring  1778 


Funding: Work supported by NSF Grant #PHY0110253 and DOE Contract DEAC0584ER40150. The Small Isochronous Ring has been operational at Michigan State University since December 2003. It is used for experimental studies of the beam dynamics in highintensity isochronous cyclotrons and synchrotrons at the transition energy. The operational experience with SIR has proven that the ring can be successfully used to study space charge effects in accelerators. The low velocity of beam particles in the ring allowed us to achieve a high accuracy of longitudinal profile measurements that is difficult to achieve in fullsize accelerators. The experimental data obtained in the ring was used for validation of multiparticle, spacecharge codes CYCO and WARP3D. Inspired by the solid performance of SIR in the isochronous regime, we consider options for expanding the scope of the beam physics studied in the ring. In this paper, we outline possible future experiments and discuss required modifications of the ring optics and hardware. 

TPAT023  Tests of a 3D Self Magnetic Field Solver in the Finite Element Gun Code MICHELLE  1814 


Funding: Work supported by ONR. We have recently implemented a prototype 3d self magnetic field solver in the finiteelement gun code MICHELLE. The new solver computes the magnetic vector potential on unstructured grids. The solver employs edge basis functions in the curlcurl formulation of the finiteelement method. A novel current accumulation algorithm takes advantage of the unstructured grid particle tracker to produce a compatible source vector, for which the singular matrix equation is easily solved by the conjugate gradient method. We will present some test cases demonstrating the capabilities of the prototype 3d self magnetic field solver. One test case is self magnetic field in a square drift tube. Another is a relativistic axisymmetric beam freely expanding in a round pipe. 

TPAT026  Synergia: An Advanced ObjectOriented Framework for Beam Dynamics Simultation  1925 


Synergia is a 3D, parallel, particleincell beam dynamics simulation toolkit. At heart of the software development effort is the integration of two extant objectoriented accelerator modeling frameworks–Impact written in Fortran 90 and mxyptlk written in C++–so that they may be steered by a third, a more flexible human interface framework, written in Python. Recent efforts are focused on the refactoring of the ImpactFortran 90 codes in order to expose more looselycoupled interfaces to the Python interface framework.  
TPAT027  Measurement of Transverse Echoes in RHIC  1955 


Funding: Work supported by U.S. DOE under contract No DEAC0298CH10886. Beam echoes are a very sensitive method to measure diffusion, and longitudinal echo measurements were performed in a number of machines. In RHIC, for the first time, a transverse beam echo was observed after applying a dipole kick followed by a quadrupole kick. After application of the dipole kick, the dipole moment decohered completely due to lattice nonlinearities. When a quadrupole kick is applied at time T after the dipole kick, the beam recohered at time 2T thus showing an echo response. We describe the experimental setup and measurement results. In the measurements the dipole and quadrupole kick amplitudes, amplitude dependent tune shift, and the time between dipole and quadrupole kick were varied. In addition, measurements were taken with gold bunches of different intensities. These should exhibit different transverse diffusion rates due to intrabeam scattering. 

TPAT028  TRACK: The New Beam Dynamics Code  2053 


Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W31109ENG38.
The new raytracing code TRACK was developed* to fulfill the special requirements of the RIA accelerator systems. The RIA lattice includes an ECR ion source, a LEBT containing a MHB and a RFQ followed by three SC linac sections separated by two stripping stations with appropriate magnetic transport systems. No available beam dynamics code meet all the necessary requirements for an endtoend simulation of the RIA driver linac. The latest version of TRACK was used for endtoend simulations of the RIA driver including errors and beam loss analysis.** In addition to the standard capabilities, the code includes the following new features: i) multiple charge states ii) realistic stripper model; ii) static and dynamic errors iii) automatic steering to correct for misalignments iv) detailed beamloss analysis; v) parallel computing to perform large scale simulations. Although primarily developed for simulations of the RIA machine, TRACK is a general beam dynamics code. Currently it is being used for the design and simulation of future proton and heavyion linacs at TRIUMF, Fermilab, JLAB and LBL.
*P.N. Ostroumov and K.W. Shepard. Phys. Rev. ST. Accel. Beams 11, 030101 (2001). **P.N. Ostroumov, V. N. Aseev, B. Mustapha. Phys. Rev. ST. Accel. Beams, Volume 7, 090101 (2004). 

TPAT029  RIA Beam Dynamics: Comparing TRACK to IMPACT  2095 


Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W31109ENG38. In order to benchmark the newly developed beam dynamics code TRACK we have performed comparisons with well established existing codes. During code development, codes like TRANSPORT, COSY, GIOS and RAYTRACE were used to check TRACK's implementation of the different beam line elements. To benchmark the endtoend simulation of the RIA driver linac, the simulation of the lowenergy part (from the ion source to the entrance of the SC linac) was compared with PARMTEQ and found to agree well. For the simulation of the SC linac the code IMPACT is used. Prior to these simulations, the code IMPACT had to be updated to meet the special requirements of the RIA driver linac. Features such as multiple charge state acceleration, stripper simulation and beam collimation were added to the code. IMPACT was also modified to support new types of rf cavities and to include fringe fields for all the elements. This paper will present a comparison of the beam dynamics simulation in the RIA driver linac between the codes TRACK and IMPACT. A very good agreement was obtained which represents another validation of both codes. 

TPAT030  Transverse Beam Matching Application for SNS  2143 


Funding: SNS is managed by UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. An automated transverse beam matching application has been developed for the Spallation Neutron Source (SNS) beam transport lines. The application is written within the XAL Java framework and the matching algorithm is based on the simplex optimization method. Other functionalities, such as emittance calculated from profile monitor measurements (adopted from a LANL Fortran code), profile monitor display, and XAL online model calculation, are also provided by the application. Test results obtained during the SNS warm linac commissioning will be reported. A comparison between the emittances obtained from this application and an independent Trace3D routine will also be shown. 

TPAT031  Painting SelfConsistent Beam Distributions in Rings  2194 


Funding: SNS is managed by UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. We define selfconsistent beam distributions to have the following properties: 1) timeindependence or periodicity, 2) linear space charge forces, and 3) maintainance of their defining shape and density under all linear transformations. The periodic condition guarantees zero spacechargeinduced halo growth and beam loss during injection. Some selfconsistent distributions can be manipulated into flat, or even pointlike, beams, which makes them interesting to colliders and to heavyion fusion. This paper presents methods for painting 2D and 3D selfconsistent distributions and for their manipulation to produce flat and pointlike beams. 

TPAT032  Transverse Stability Studies of the SNS Ring  2254 


Funding: SNS is managed by UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. Detailed studies of the transverse stability of the SNS ring have been carried out for realistic injection scenarios. For coasting beam models and single harmonic impedances, analytic and computational results including phase slip, chromaticity, and space charge are in excellent agreement. For the dominant extraction kicker impedance and bunched beams resulting from injection, computationally determined stability thresholds are significantly higher than for coasting beams. At this time, we have no analytic model to treat the bunched beam case, but we present a formulation that provides an approach to this problem. 

TPAT033  Experimental Characterizations of 4D Transverse PhaseSpace of a Compressed Beam  2263 


Funding: Work supported by U.S. DOE. Coherent synchrotron radiation can significantly distort beam phase spaces in longitudinal direction and bending plane through a bunch compressor. A tomography technique is used to reconstruct transverse phase space of electron beam. Transverse 4D phase spaces are systematically measured at UCLA/ATF compressor and their characteristics with different bunch compression conditions are analyzed. 

TPAT034  Manipulations of Double Electron Beams within One RF Period for Seeded SMLWFA Experiment  2312 


Funding: Work supported by U.S. DOE. Although seeded SMLWFA only requires one electron beam to initiate the laser wakefield, it would be highly desirable to have a second electron beam traveling after the first one to probe the accelerated electrons. To create and preserve significant amount of wakefield in the STELLA SMLWFA experiment, the first ebeam needs to be tiny (<40 microns FWHM) in size and short in length within the plasma. To probe the wakefield which is damped within 10 ps for certain plasma density, the separation between the first and second beams needs to be within one RF period and the second ebeam must have smaller energy spread and smaller size. Design of double beams in one RF period to meet the strict requirements and the preliminary beam study at BNLATF facility are presented. The scheme of double beams with ATF bunch compressor is also discussed. 

TPAT035  Coherent Synchrotron Radiation from an Electron Beam in a Curved Waveguide  2390 


Funding: Research supported by the office of Naval Research and the Joint Technology Office. The radiation emitted by a pulsed electron beam as it travels on a circular trajectory inside a waveguide is calculated using a 3D simulation. Forwardpropagating wave equations for the fields in the waveguide are calculated by a perturbation of the Maxwell equations where the radius of curvature is large compared to the dimensions of the waveguide. These are integrated selfconsistently with the distribution of charge in the beam to provide the complete fields (electric and magnetic) for all times during the passage of the beam through the waveguide and therefore are applicable to sections of any length or combinations thereof. The distribution of electrons and their momentum are also modified selfconsistently so that the results may be used to estimate the effect of the radiation on the beam quality (emittance and energy spread). 

TPAT036  Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization  2452 


Funding: Research supported by the U.S. Department of Energy. Plasmas are employed as a medium for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1100 times the ion beam density and at a length ~ 0.11 m would be suitable. To produce 1 meter plasma, largevolume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic. High voltage (~ 15 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long produced plasma densities ~ 5x1011 cm3. The source was integrated into the experiment and successfully charge neutralized the K ion beam. Presently, the 1 meter source is being fabricated. It will be characterized and integrated into NDCX for charge neutralization experiments. Experimental results will be presented. 

TPAT037  Simulating the LongDistance Propagation of Intense Beams in the Paul Trap Simulator Experiment  2491 


Funding: Research supported by the U.S. Department of Energy. The Paul Trap Simulator Experiment (PTSX) makes use of a compact Paul trap configuration with quadrupolar oscillating wall voltages to simulate the propagation of intense charged particle beams over distances of many kilometers through magnetic alternatinggradient transport systems. The simulation is possible because of the similarity between the transverse dynamics of particles in the two systems. Onecomponent pure cesium ion plasmas have been trapped that correspond to normalized intensity parameters s < 0.8, where s is the ratio of the square of the plasma frequency to twice the square of the average transverse focusing frequency. The PTSX device confines the plasma for hundreds of milliseconds, which is equivalent to beam propagation over tens of kilometers. Results are presented for experiments in which the amplitude of the oscillating confining voltage waveform has been modified as a function of time. A comparison is made between abrupt changes in amplitude and adiabatic changes in amplitude. The effects of varying the frequency are also discussed. A barium ion source and a laser system have been installed and initial measurements made with this system are presented. 

TPAT038  Chaos in TimeDependent SpaceCharge Potentials  2515 


We consider a spherically symmetric, homologously breathing, spacechargedominated beam bunch in the spirit of the particlecore model. The question we ask is: How does the time dependence influence the population of chaotic orbits? The static beam has zero chaotic orbits; the equation of particle motion is integrable up to quadrature. This is generally not true once the bunch is set into oscillation. We quantify the population of chaotic orbits as a function of space charge and oscillation amplitude (mismatch). We also apply a newly developed measure of chaos, one that distinguishes between regular, sticky, and wildly chaotic orbits, to characterize the phase space in detail. We then introduce colored noise into the system and show how its presence modifies the dynamics. One finding is that, despite the presence of a sizeable population of chaotic orbits, halo formation in the homologously breathing beam is much less prevalent than in an envelopematched counterpart wherein an internal collective mode is excited.  
TPAT039  WaveletBased Poisson Solver for Use in ParticleinCell Simulations  2601 


Funding: Work of B.T., D.M. and C.L.B. is supported by Air Force contract FA9471040C0199. Work of I.V.P. is supported by the U.S. Department of Energy contract DEAC0376SF00098.
We report on a successful implementation of a waveletbased Poisson solver for use in 3D particleincell simulations. One new aspect of our algorithm is its ability to treat the general (inhomogeneous) Dirichlet boundary conditions. The solver harnesses advantages afforded by the wavelet formulation, such as sparsity of operators and data sets, existence of effective preconditioners, and the ability simultaneously to remove numerical noise and further compress relevant data sets. Having tested our method as a standalone solver on two model problems, we merged it into IMPACTT to obtain a fully functional serial PIC code. We present and discuss preliminary results of application of the new code to the modelling of the Fermilab/NICADD and AES/JLab photoinjectors.
Corresponding author: B.T. (bterzic@nicadd.niu.edu) 

TPAT040  Actual Stationary State for Plasma Lens  2619 


The electrostatic plasma lens (PL) provides an attractive and unique tool for manipulating highcurrent heavy ion beams. The fundamental concept of the PL is based on the use of magnetically insulated electrons and equipotentialization of magnetic field lines. Rigorous application of PL is, however, limited. The reason is the estimation behaviour of electrons for complicated magnetic fields runs into severe difficults.We show that there are specific conditions that admit steadystate of a longitudinal motion, and consider a question of it stability. These results are needed to develop an optimized PL with minimal spherical aberation, in party by optimization of the magnetic field conficuration in the lowmagneticfield range.  
TPAT041  On the VlasovMaxwell Equations  2654 


There are many interesting physical question which based on of the solution VlasovMaxwell Equation (VME). However, the procedure of solve is very difficult and hard. But it is often preferable, on physical grounds, to a common point of view. Such point of view maybe a structure of some solution. We define and discuss the notaion of structure for the distribution function and prove, the structure of the Lorentz force represent the structure of the one. At the time of the discovery of the integrable systems the question of VME integrability had been considered. Moreover, as example, we consider, by means of this approach, the relation integrability and dispersion with a spectra of Vlasov's operat.  
TPAT042  Progress on a Vlasov Treatment of Coherent Synchrotron Radiation from Arbitrary Planar Orbits  2699 


Funding: Support from DOE grants DEAC0276SF00515 and DEFG0299ER1104 is gratefully acknowledged.
We study the influence of coherent synchrotron radiation (CSR) on particle bunches traveling on arbitrary planar orbits between parallel conducting plates (shielding). The time evolution of the phase space distribution is determined by solving the VlasovMaxwell equations in the time domain. This provides lower numerical noise than the macroparticle method, and allows the study of emittance degradation and microbunching in bunch compressors. We calculate the fields excited by the bunch in the lab frame using a formula simpler than that based on retarded potentials.* We have developed an algorithm for solving the Vlasov equation in the beam frame using arc length as the independent variable and our method of local characteristics (discretized PerronFrobenius operator).We integrate in the interaction picture in the hope that we can adopt a fixed grid. The distribution function will be represented by Bsplines, in a scheme preserving positivity and normalization of the distribution. The transformation between lab and beam frame is carefully treated. Here we report on our implementation of the algorithm for a chicane bunch compressor with linear energy chirp and take steps to treat the nonlinear case.
*"Vlasov Treatment of Coherent Synchrotron Radiation from Arbitrary Planar Orbits" to be published in the Proceedings of ICAP04, St. Petersburg, R. Warnock, G. Bassi and J. A. Ellison. 

TPAT043  The MICHELLE 2D/3D ES PIC Code: Advances and Applications  


Funding: Office of Naval Research, Naval Research Laboratory.
MICHELLE is a new 2D/3D steadystate and timedomain particleincell (PIC) code* that employs electrostatic and now magnetostatic finiteelement field solvers. The code has been used to design and analyze a wide variety of devices that includes multistage depressed collectors, gridded guns, multibeam guns, annularbeam guns, sheetbeam guns, beamtransport sections, and ion thrusters. Latest additions to the MICHELLE/Voyager tool are as follows: 1) a prototype 3D self magnetic field solver using the curlcurl finiteelement formulation for the magnetic vector potential, employing edge basis functions and accumulating current with MICHELLE's new unstructured grid particle tracker, 2) the electrostatic field solver now accommodates dielectric media, 3) periodic boundary conditions are now functional on all grids, not just structured grids, 4) the addition of a global optimization module to the user interface where both electrical parameters (such as electrode voltages)can be optimized, and 5) adaptive mesh refinement improvements. Applications illustrating these latest additions will be presented, including a relativistic sheet beam gun, a relativistic MIG gun, and a depressed collector optimization example.
*John Petillo, et al., IEEE Trans. Plasma Sci., vol. 30, no. 3, June 2002, pp. 12381264. 

TPAT045  Equilibrium and Stability in the Transport of Intense OffAxis Beams in Periodic Focusing Systems  


Funding: Work supported by Brazilian agencies CNPq, CAPES, and FAPERGS.
A general equation for the centroid motion of free, continuous, intense beams propagating offaxis in solenoidal periodic focusing fields is derived.* The centroid equation is found to be independent of the specific beam distribution and may exhibit unstable solutions. A new Vlasov equilibrium for offaxis beam propagation is also obtained. Properties of the equilibrium and the relevance of centroid motion to beam confinement are discussed. The effects of a conducting pipe encapsulating the beam are also investigated.** It is shown that the charge induced at the pipe may generate chaotic orbits which can be detrimental to the beam transport.
*J.S. Moraes, R. Pakter, F.B. Rizzato, Phys. Rev. Lett., accepted for publication (2004). **J.S. Moraes, R. Pakter, F.B. Rizzato, Phys. Plasmas, accepted for publication (2004). 

TPAT046  Nonlinear Stability of Intense Mismatched Beams in a Uniform Focusing Field  2941 


Funding: Work supported by Brazilian agencies CNPq, CAPES, and FAPERGS. We investigate the nonlinear coupling between axisymmetric and elliptic oscillations in the dynamics of intense beams propagating in a uniform magnetic focusing field. It is shown that finite amplitude mismatched oscillations of an initially round beam may destabilize elliptic oscillations, heavily affecting stability and the shape of the beam. This is a potential mechanics for beam particle loss in such systems. Self consistent simulations are performed to verify the findings. 

TPAT047  A Space Charge Compensation Study of Low Energy Hydrogen Ion Beams  2947 


Funding: Work supported by the European CommunityResearch Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3CT2003506395).
Highpower accelerators are being studied for several projects including accelerator driven neutron or neutrino sources. The low energy part of these facilities has to be carefully optimized to match the beam requirements of the higher energy parts. The complexity of high intensity beam dynamics in the low energy line is essentially due to the nonlinear space charge effects. The PIC code CARTAGO* has been developed in order to simulate the beam transport at low energy including the temporal evolution effects of the space charge compensation. This paper relates the structure and the numerical methods of a 2D (r,z) new version of the code. The effects of the longitudinal space charge, the image charge and external 2D (r,z) magnetic field were included. The results of H^{+} and H^{} beam transports using solenoid lenses are discussed. Space charge compensation degrees are given for each studied cases.
*A. Ben Ismail et al., in Space Charge Compensation in Low Energy Proton Beams, proceeding of the International Linear Accelerator Conference, Lübeck, 2004. 

TPAT048  The Transverse Nonlinear Tune Shift as Stabilising Factor in Halo Creation in Space Charge Dominated Beam  3004 


Funding: We acknowledge the support of the European CommunityResearch Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3CT2003506395). One of the most important problems for space charge dominated beam in the low energy part of superconducting linac is halo creation. Many authors show one of the key effects in halo creatiation is parametric resonance due to the mismatched betafunction oscillation (between core and particle). To estimate parametric resonance conditions the nonlinear tune shift for binomial distributed beam is described theoretically in this article. Simultaneously the beam dynamics simulation 3D PIC code was developed. The transverse oscillation frequencies compared with parametric resonance criteria. As a result the recommendation for space charge shift is concluded to minimize halo creation. 

TPAT049  Comparison of Beam Dynamic in Different Superconducting Options of Low Energy High Intense Linac  3058 


Funding: We acknowledge the support of the European CommunityResearch Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3CT2003506395). At present the superconducting proton linacs have obvious applications in energy range ~1001000 MeV. For the lower energy the comprehensive investigations are required. In this article the various variants of superconducting options from 3MeV up to 100MeV are discussed. The considered variants include both the conventional combination of halfwave and spoke cavity with quadrupoles and new schemes. In conclusion the table of major parameters for different structures is given. 

TPAT050  Beam Dynamics Design of the L3BT for JPARC  3091 


L3BT is beam transportation line from the linac to the 3GeV RCS which is the part of the accelerators for the HighIntensity Proton Accelerator Facility Project, JPARC.In this paper, especially results of the beam simulation of the injection section of the L3BT are presented. And the matching of rms envelopes and dispersion function for space charge dominated beams are also discussed.  
TPAT051  Asymmetrical Spectrum Observed at the KEKB High Energy Electron Ring  3176 


KEKB is a multibunch, highcurrent, electron/positron collider for B meson physics. The two beams collide at one interaction point (IP) with a finite horizontal crossing angle. The luminosity achieved at KEKB is the best in the world. In order to keep up the performance, the tune of a noncolliding bunch, placed just after a colliding bunchtrain, is continuously monitored. It was observed that an electron bunch showed an asymmetrical distribution biased to a higher tune in the vertical tunespectrum. We found that the asymmetrical spectrum was reinforced by the beambeam interaction, though the electron bunch did not collide. The asymmetry was reinforced moreover, as the electron bunch approached a bunchtrain further. These observations suggest that the asymmetry in the spectrum is not related to trappedions or fastions observed in an electron single beam, but related to ions produced by the beambeam interaction, which makes the particles scattered and they might yield new ions due to the collision with residual gas. We can imagine that the ions are accumulated along a bunchtrain and some ions survive after colliding bunches passed through in the electron ring. A quantitative analysis remains for future study.  
TPAT054  Dispersion Matching of a Space Charge Dominated Beam at Injection into the CERN PS Booster  3283 


In order to match the dispersion at injection into the CERN PS Booster, the optics of the injection line was simulated using two different codes (MAD and TRACE). The simulations were benchmarked versus experimental results. The model of the line was then used to rematch the dispersion. Experimental results are presented for different optics of the line. Measurements with varying beam current show the independence of the measured quantity of spacecharge effects.  
TPAT055  On Start to End Simulation and Modeling Issues of the Megawatt Proton Beam Facility at PSI  3319 


At the Paul Scherrer Institut (PSI) we routinely extract a one megawatt (CW) proton beam out of our 590 MeV Ring Cyclotron. In the frame of the ongoing upgrade program, large scale simulations have been undertaken in order to provide a sound basis to assess the behaviour of very intense beams in cyclotrons. The challenges and attempts towards massive parallel three dimensional startto end simulations will be discussed. The used state of the art numerical tools (mapping techniques, time integration, parallel FFT and finite element based multigrid Poisson solver) and their parallel implementation will be discussed. Results will be presented in the area of: space charge dominated beam transport including neighbouring turns, eigenmode analysis to obtain accurate electromagnetic fields in large the rf cavities and higher order mode interaction between the electromagnetic fields and the particle beam. For the problems investigated so far a good agreement between theory i.e. calculations and measurements is obtained.  
TPAT057  Observations of UHF Oscillations in the IPNS RCS Proton Bunch  3375 


Funding: This work is supported by the U.S. Department of Energy under contract no. W31109ENG38. The Intense Pulsed Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS) accelerates 3.2x 10^{12} protons from 50 MeV to 450 MeV in a single bunch (h=1) at 30 Hz. The rf frequency varies from 2.21 MHz to 5.14 MHz during the 14.2 ms acceleration interval. To maintain stability of the bunch, phase modulation is introduced to the rf at approximately twice the synchrotron frequency (synchrotron tune is 0.0014). This phase modulation causes a parametric quadrupole oscillation to develop in the bunch, and as this occurs, the bunch spectrum shows a significant increase in high frequency content. Without phase modulation, the beam experiences an instability which results in the loss of a large fraction of the charge 24 ms prior to extraction. It is unclear if the stability imparted to the beam by phase modulation comes from the quadrupole oscillation or from the high frequency excitation. A longitudinal tracking code is presently being modified to include amplitude and phase modulation of the bunch. The numerical analysis will be used to compare growth rates with those observed in the machine. The results of this analysis will be important as we introduce second harmonic rf with a new third cavity in the RCS later in 2005. 

TPAT058  Calculation of Electron Beam Potential Energy from RF Photocathode Gun  3441 


Funding: U.S. Department of Energy. In this paper, we consider the contribution of potential energy to beam dynamics as simulated by PARMELA at low energies (10  30MeV). We have developed a routine to calculate the potential energy of the relativistic electron beam using the static coulomb potential in the rest frame (first order approximation as in PARMELA). We found that the potential energy contribution to the beam dynamics could be very significant, particularly with high charge beams generated by an RF photocathode gun. Our results show that when the potential energy is counted correctly and added to the kinetic energy from PARMELA, the total energy is conserved. Simulation results of potential and kinetic energies for short beams (~1 mm) at various charges (1  100 nC) generated by a high current RF photocathode gun are presented. 

TPAT059  Space Charge Experiments and Simulation in the Fermilab Booster  3453 


Funding: Scientific Discovery through Advanced Computing project, "Advanced Computing for 21st Century Accelerator Science and Technology," U.S. DOE/SC Office of High Energy Physics and the Office of Advanced Scientific Computing Research. We have studied space charge effects in the Fermilab Booster. Our studies include investigation of coherent and incoherent tune shifts and halo formation. We compare experimental results with simulations using the 3D space charge package Synergia. 

TPAT060  Overview of the Synergia 3D MultiParticle Dynamics Modeling Framework  3490 


Funding: Scientific Discovery through Advanced Computing project, "Advanced Computing for 21st Century Accelerator Science and Technology," U.S. DOE/SC Office of High Energy Physics and the Office of Advanced Scientific Computing Research. High precision modeling of spacecharge effects is essential for designing future accelerators as well as optimizing the performance of existing machines. Synergia is a highfidelity parallel beam dynamics simulation package with fully three dimensional spacecharge capabilities and a higherorder optics implementation. We describe the Synergia framework and model benchmarks we obtained by comparing to semianalytic results and other codes. We also present Synergia simulations of the Fermilab Booster accelerator and comparisons with experiment. 

TPAT061  Accurate Iterative Analysis of the KV Equations  3535 


Funding: Supported in part by the U.S. Department of Energy under Contract No. DEAC0376SF00098. Previous solutions of the KV equations have either yielded poor accuracy or have been complex and difficult to follow. We describe a new approach, simple in concept, easy to use, with accuracy substantially improved over previous treatments. The results are given in the same form as the smooth approximation but include a few correction terms obtained from the field gradient integrated along the axis of a quadrupole cell. The input quantities–quadrupole field, beam current, and emittance–yield the average beam radius, the maximum envelope excursion, and the depressed and undepressed tunes. For all values of the input parameters, the results are much closer to the exact values from simulations than are results from the smooth approximation. For example, with the parameters adjusted for an exact phase advance of 83.4 degrees and 50% tune depression, both tunes are in error by less than 0.5%–over 22 times better than the smooth approximation. The error in maximum radius is 0.04%, improved by a factor of 80. The new method and its application to a wide range of cases will be presented. 

TPAT062  Uncorrelated Energy Spread and Longitudinal Emittance for a Photoinjector Beam  3570 


Longitudinal phase space properties of a photoinjector beam are important in many areas of highbrightness beam applications such as bunch compression, transversetolongitudinal emittance exchange, and highgain freeelectron lasers. In this paper, we discuss both the rf and the space charge contributions to the uncorrelated energy spread of the beam generated from a laserdriven rf gun. We compare analytical expressions for the uncorrelated energy spread and the longitudinal emittance with numerical simulations and recent experimental results.  
TPAT065  Damping Transverse Instabilities in the Tevatron Using AC Chromaticity  3665 


Funding: Operated by Universities Research Association Inc. under Contract No. DEAC0276CH03000 with the U.S. Department of Energy.
Several papers*,** have suggested possibility of using varying chromaticity to damp the headtail instability. We test this by cycling the chromaticity sextupole magnets in the Tevatron near the synchrotron frequency to see if the headtail stability threshold is increased. Further we compare the turnbyturn evolution of a bunch slice in the presence of varying chromaticity to a model previously developed.
*W.H. Cheng, A. M. Sessler, and J. S. Wurtele, Phys. Rev. Lett. 78, 4565 (1997). **T. Nakamura in Proceedings of the 1995 IEEE Particle Accelerator Conference (IEEE, Dallas, 1995), Vol. 5, p. 3100. 

TPAT066  Significance of Space Charge and the Earth Magnetic Field on the Dispersive Characteristics of a Low Energy Electron Beam  3691 


Funding: This work is funded by U.S. Dept. of Energy grant numbers DEFG0294ER40855 and DEFG0292ER54178.
The combination of energy spread and space charge provides a rich domain for interesting beam dynamics that are currently not well understood. The University of Maryland Electron Ring (UMER) [1] is a small scaled ring designed to probe the littleknown regions of higher beam intensities using lowenergy electrons. As such, design, commissioning and operation of UMER present many challenges, some quite novel. For example the UMER beam energy of 10 keV makes the beam very sensitive to the Earth magnetic field, which we can fortunately use to assist in bending the beam. This paper presents a systematic simulation study of the interaction of space charge and energy spread, with and without the earth magnetic field.
*"Commissioning of the University of Maryland Electron Ring (UMER)," S. Bernal, et al., this conference. 

TPAT067  Study of Longitudinal SpaceCharge Wave Dynamics in SpaceCharge Dominated Beams  3712 


Funding: Work supported by the U.S. Department of Energy, Office of Science. Understanding the dynamics of longitudinal space^{} charge waves is very important for advanced accelerator research. Although analytical solutions of spacecharge wave equations based on the cold fluid model exist in one dimension, there are few results for twodimensional wave evolution. Onedimensional theory predicts two eigen solutions, given an initial perturbation. One is called the fast wave, which moves toward the beam head in the beam frame and the other is termed the slow wave, which moves backward in the beam frame. In this paper, we report experimental results of space charge wave studies conducted on a 2.3 meter long straight beam line at the University of Maryland. An energy analyzer is used to directly measure the energy of spacecharge waves at the end of the transport line, which demonstrates the decomposition of an initial current perturbation into a slow wave and a fast wave. A PIC code, WARP [1], is used to simulate this experiment and the behavior of longitudinal waves in spacecharge dominated beams in an RZ geometry. Simulations shown here also demonstrate if the initial current and velocity perturbation strengths are chosen properly, only fast or slow waves could be selectively generated. 

TPAT068  A Fast Faraday Cup for the Neutralized Drift Compression Experiment  3765 


Funding: Research supported by the U.S. Department of Energy. Heavy ion drivers for high energy density physics applications and inertial fusion energy use spacechargedominated beams which require longitudinal bunch compression in order to achieve sufficiently high beam intensity at the target. The Neutralized Drift Compression Experiment1A (NDCX1A) at Lawrence Berkeley National Laboratory (LBNL) is used to determine the effective limits of neutralized drift compression. NDCX1A investigates the physics of longitudinal drift compression of an intense ion beam, achieved by imposing an initial velocity tilt on the drifting beam and neutralizing the beam's spacecharge with background plasma. Accurately measuring the longitudinal compression of the beam pulse with high resolution is critical for NDCX1A, and an understanding of the accessible parameter space is modeled using the LSP particleincell (PIC) code. The design and preliminary experimental results for an ion beam probe which measures the total beam current at the focal plane as a function of time are summarized. 

TPAT069  Numerical Studies of Electromagnetic Instabilities in Intense Charged Particle Beams with Large Energy Anisotropy  3780 


Funding: Research supported by the U.S. Department of Energy. In intense charged particle beams with large energy anisotropy, free energy is available to drive transverse electromagnetic Weibeltype instabilities. Such slowwave transverse electromagnetic instabilities can be described by the socalled Darwin model, which neglects the fastwave portion of the displacement current. The Weibel instability may also lead to an increase in the longitudinal velocity spread, which would make the focusing of the beam difficult and impose a limit on the minimum spot size achievable in heavy ion fusion experiments. This paper reports the results of recent numerical studies of the Weibel instability using the Beam Eigenmode And Spectra (bEASt) code for spacechargedominated, lowemittance beams with large tune depression. To study the nonlinear stage of the instability, the Darwin model is being developed and incorporated into the Beam Equilibrium Stability and Transport(BEST) code. 

TPAT070  Intensity and BunchShape Dependent Beam Loss Simulation for the SIS100  3807 


We have studied the combined influence of magnet nonlinearities, space charge and bunch shapes consistent with different RF scenarios on the longterm loss in the planned SIS100 synchrotron of the FAIR project. The simulation is a 3D tracking with "frozenin" space charge calculation employing the MICROMAP code. Comparing a oneharmonic RF scenario with an alternative doubleharmonic scenario we find that for the same absolute beam loss roughly twice the number of particles can be stored in the doubleRF system. Moreover, a barrier bucket RF scenario is found to be loss free. This is due to the fact that loss is caused here by spacecharge induced periodic resonance crossing, which is absent for the strictly flat bunch profile of the barrier case.  
TPAT072  LongTerm Simulation of BeamBeam Effects in the Tevatron at Collision Energy  3871 


The weakstrong beambeam effect is expected substantially to contribute to the degradation of beam lifetimes in the Tevatron at collision energy. We have expanded an existing multiprocessor code (which previously was applied to the Tevatron at injection energy* to include chromatic and nonlinear lattice effects as well as a fullycoupled treatment of the lattice in different approximations.** We obtain lifetime predictions by doing temporal statistics on the tracking results of a weighted macroparticle distribution and fitting it to a class of solutions for the diffusion equation. We present typical results of parameter scans.
*A. Kabel, Y. Cai, B. Erdelyi, T. Sen, M. Xiao; Proceedings of PAC03. **A. Kabel, this Conference. 

TPAT076  Measurement of the LuminousRegion Profile at the PEPII IP, and Application to e± BunchLength Determination  3973 


The threedimensional luminosity distribution at the interaction point (IP) of the SLAC BFactory is measured continuously, using e^{+}e^{} –> e^{+}e^{} and e+e –> mu+mu events reconstructed online in the silicon tracker of the BaBar detector. The centroid of the transverse luminosity profile provides a very precise and reliable monitor of medium and longterm orbit drifts at the IP. The longitudinal centroid is sensitive to variations in the relative RF phase of the colliding beams, both over time and differentially along the bunch train. The measured horizontal r.m.s. width of the distribution is consistent with a sizeable dynamicbeta effect; it is also useful as a benchmark of strongstrong beambeam simulations. The longitudinal luminosity distribution depends on the e± bunch lengths and vertical IP betafunctions, which can be different in the high and lowenergy rings. Using independent estimates of the betafunctions, we analyze the longitudinal shape of the luminosity distribution in the presence of controlled variations in accelerating RF voltage and/or beam current, to extract separate measurements of the e^{+} and e^{} bunch lengths.  
TPAT077  BeamBeam Study on the Upgrade of Beijing Electron Positron Collider  4000 


It is an important issue to study the beambeam interaction in the design and performance of such a high luminosity collider as BEPCII, the upgrade of Beijing Electron Positron Collider. The weakstrong simulation is generally used during the design of a collider. For performance a large scale tune scan, the weakstrong simulation studies on beambeam interaction were done, and the geometry effects were taken into account The strongstrong simulation studies were done for investigating the luminosity goal and the dependence of the luminosity on the beam parameters.  
TPAT078  Coherent BeamBeam Modes in the CERN Large Hadron Collider (LHC) for Multiple Bunches, Different Collisions Schemes and Machine Symmetries  4030 


In the LHC almost 3000 bunches in each beam will collide near several experimental regions and experience headon as well as long range beambeam interactions. In addition to single bunch phenomena, coherent bunch oscillations can be excited. Due to the irregular filling pattern and the unsymmetric collision scheme, a large number of possible modes must be expected, with possible consequences for beam measurements. To study these effects, a simulation program was developped which allows to evaluate the interaction of many bunches. It is flexible enough to easily implement any possible bunch configuration and collision schedule and also to study the effect of machine imperfections such as optical asymmetries. First results will be presented and future developments are discussed.  
TPAT079  Importance of the Linear Coupling and Multipole Compensation of LongRange BeamBeam Interactions In Tevatron  4039 


Funding: The US Department of Energy under Grant No. DEFG0204ER41288. In Tevatron, serious longrange beambeam effects are due to many parasitic collisions that are distributed around the ring. Because of this nonlocalized nature of longrange beambeam interactions, the multipole compensation with oneturn or sectional maps aims a global compensation of longrange beambeam interactions. Since nonlinear beam dynamics in a storage ring can usually be described by a oneturn map that contains all global information of system nonlinearities, by minimizing nonlinear terms of the maps orderbyorder with a few groups of multipole correctors, one could reduce the nonlinearity globally. Since a large beam separation is typical at parasitic points, in the phasespace region that is relevant to the beam, longrange beambeam interactions can be expanded into a Taylor series around the beam separation and be included into the oneturn map for the global compensation. To examine the effect of this multipole compensation scheme, the emittance growth of both p and pbar beam in Tevatron were studied with a beambeam simulation. The result showed that the multipole compensation can significantly reduces the emittance growth of the pbar beam due to longrange beambeam interactions. 

TPAT081  Observation of ElectronIon Effects at RHIC Transition  4087 


Funding: Work performed under the auspices of the U.S. Department of Energy. Electron cloud is found to be a serious obstacle on the upgrade path of the Relativistic Heavy Ion Collider (RHIC). At twice the design number of bunches, electronion interactions cause significant instability, emittance growth, and beam loss along with vacuum pressure rises when the beam is accelerated across the transition. 

TPAT082  Phonon Modes and the Maintenance Condition of a Crystalline Beam  4111 


Funding: * Work performed under the auspices of the U.S. Department of Energy.
Previously it has been shown that the maintenance condition for a crystalline beam requires that there not be a resonance between the crystal phonon frequencies and the frequency associated with a beam moving through a lattice of N periods. This resonance can be avoided provided the phonon frequencies are all below half of the lattice frequency. Here we make a detailed study of the phonon modes of a crystalline beam. Analytic results obtained in a “smooth approximation” using the groundstate crystalline beam structure is compared with numerical evaluation employing Fourier transform of Molecular Dynamic (MD) modes. The MD also determines when a crystalline beam is stable. The maintenance condition, when combined with either the simple analytic theory or the numerical evaluation of phonon modes, is shown to be in excellent agreement with the MD calculations of crystal stability.
[1] XP. Li, A. M. Sessler, J. Wei, EPAC (1994) p. 1379  1381. ‘Necessary Conditions for Attaining a Crystalline Beam''}[2] J. Wei, H. Okamoto, A.M. Sessler, Phys. Rev. Lett., Vol. 80, p. 26062609 (1998). 

TPAT083  Computational Study of the BeamBeam Effect in Tevatron Using the LIFETRAC Code  4117 


Funding: Work supported by the Universities Research Assos., Inc., under contract DEAC0276CH03000 with the U.S. Dept. of Energy. Results of a comprehensive numerical study of the beambeam effect in the Tevatron are presented including the dependence of the luminosity lifetime on the tunes, chromaticity and optics errors. These results help to understand the antiproton emittance blowup routinely observed in the Tevatron after the beams are brought into collision. To predict a long term luminosity evolution, the diffusion rates are increased to represent long operation time (~day) by using a small number of simulated turns. To justify this approach, a special simulation study of interplay between nonlinear beambeam resonances and diffusion has been conducted. A number of ways to mitigate the beambeam effects are discussed, such as increasing bunch spacing, separation between the beams and beambeam compensation with electron lenses. 

TPAT084  LIFETRAC Code for the WeakStrong Simulation of the BeamBeam Effect in Tevatron  4138 


Funding: Work supported by the Universities Research Assos., Inc., under contract DEAC0276CH03000 with the U.S. Dept. of Energy. A package of programs for weakstrong simulation of beambeam effects in hadron colliders is described. Accelerator optics parameters relevant to the simulation are derived from beam measurements and calculations are made using OptiM optics code. The key part of the package is the upgraded version of the LIFETRAC code which now includes 2D coupled optics, chromatic modulation of betafunctions, nonGaussian shape of the strong bunches and nonlinear elements for beambeam compensation. Parallel computations are used and in the case of the Tevatron (2 main IPs + 70 parasitic IPs) the code has a productivity of ~1·10^{10} particles*turns/day on a 32node cluster of Pentium IV 1.8 GHz processors. 

TPAT085  Development of a BeamBeam Simulation Code for e^{+}e^{} Colliders  4176 


Funding: Chinese National Foundation of Natural Sciences, contract 10275079 JSPS Core University Program BEPC will be upgraded into BEPCII, and the luminosity will be about 100 times higher. We developed a three dimensional strongstrong PIC code to study the beambeam effects in BEPCII. The transportation through the arc is the same as that in Hirata's weakstrong code. The beambeam force is computed directly by solving the Poisson equation using the FACR method, and the boundary potential is computed by circular convolution. The finite bunch length effect is included by longitudinal slices. An interpolation scheme is used to reduce the required slice number in simulations. The standard message passing interface (MPI) is used to parallelize the code. The computing time increases linearly with (n+1), where n is the slice number. The calculated luminosity of BEPCII at the design operating point is less than the design value. The best area in the tune space is near (0.505,0.57) according to the survey, where the degradation of luminosity can be improved. 

TPAT086  Enhanced Optical Cooling of Particle Beams in Storage Rings  4179 


In this scheme undulators are installed in straight sections of a storage ring at distances determined by a phase advance 2pπ+π between first and second undulators and 2π between next undulators, where p=1,2,3.. . UR emitted in the first undulator pass through an optical system with movable screens 1,2 in the image plane of the particle beam. If screens let pass the UR then the past UR is amplified and pass through the second and next undulators together with the particle. Every particle loses its energy in the overlapped fields of the amplified UR and these undulators. Motion of screens in the optical system leads to particle energy losses in second and following undulators similar to losses in moving targets T1,2 in the schemes of enhanced ion cooling.* Energy losses are accompanied by a decrease of both energy spread and amplitudes of betatron oscillations that is enhanced cooling if, at first, the moving screen 2 will produce conditions of the energy loss for higher energy particles. When the screen 2 will open image of all particles the system must be closed and then the cooling process can be repeated*.
*physics/0404142. 

TPAT087  The Effect of Magnetic Field Errors on Dynamical Friction in Electron Coolers  4206 


Funding: Work supported by US DOE grants DEFG0301ER83313 and DEFG0395ER40926.
A proposed luminosity upgrade to the Relativistic Heavy Ion Collider (RHIC) includes a novel electron cooling section,* which would use ~55 MeV electrons to cool fullyionized 100 GeV/nucleon gold ions. A strong (15 T) solenoidal field will be used to magnetize the electrons and thus enhance the dynamical friction force on the ions. The physics of magnetized friction is being simulated for RHIC parameters, using the VORPAL code.** Most theoretical treatments for magnetized dynamical friction do not consider the effect of magnetic field errors, except in a parametric fashion.*** However, field errors can in some cases dramatically reduce the velocity drag and corresponding cooling rate. We present a simple analytical model for the magnetic field errors, which must be Lorentz transformed into the beam frame for use in our simulations. The simulated dynamical friction for the case of a perfect solenoidal field will be compared with results from this new model, for parameters relevant to RHIC.
*Fedotov et al., Proc. 33rd ICFA Adv. Beam Dynamics Workshop (2004). **Nieter & Cary, J. Comp. Phys. 196 (2004). ***Parkhomchuk, Nucl. Instr. Meth. Phys. Res. A 441 (2000). 

TPAT088  Consideration of Relativistic Dynamics in HighEnergy Electron Coolers  


Funding: Work supported by U.S. DOE grant DEFG0204ER84094.
A proposed electron cooler for RHIC would use ~55 MeV electrons to cool fullyionized 100 GeV/nucleon gold ions.* At two locations in the collider ring, the electrons and ions will copropagate for ~13 m, with velocities close to c and gamma>100. To lowestorder, one can Lorentz transform all physical quantities into the beam frame and calculate the dynamical friction forces assuming a nonrelativisitc, electrostatic plasma. However, we show that nonlinear space charge forces of the bunched electron beam on the ions must be calculated relativistically, because an electrostatic beamframe calculation is not valid for such short interaction times. The validity of nonrelativistic friction force calculations must also be considered. Further, the transverse thermal velocities of the highcharge (~20 nC) electron bunch are large enough that some electrons have marginally relativistic velocities, even in the beam frame. Hence, we consider relativistic binary collisions – treating the model problem of two charged particles on a line, comparing nonrelativistic dynamics, marginally relativistic (in the Darwin approximation) and fully relativistic, with retarded potentials.
*A.V. Fedotov et al., Proc. 33rd ICFA Advanced Beam Dynamics Workshop (2004), in press. 

TPAT089  Cooling Dynamics Studies and Scenarios for the RHIC Cooler  4236 


Funding: Work supported by the U.S. Department of Energy under contract No. DEAC0298CH10886 In this paper, we discuss various cooling dynamics studies for RHIC, such as an equilibrium process between intrabeam scattering within ion bunch and electron cooling, critical number of electrons needed, magnetized cooling logarithm and resulting requirements on parameters of electron beam, effects of solenoid errors, etc. We also present simulations of various possibilities of using electron cooling at RHIC, which includes cooling at the top energy, precooling at low energy, aspects of transverse and longitudinal cooling and their impact on the luminosity. Electron cooling at various collision energies both for heavy ions and protons is also discussed. 

TPAT090  Simulations of HighEnergy Electron Cooling  4251 


Funding: Work supported by the U.S. Department of Energy under contract No. DEAC0298CH10886. Highenergy electron cooling of RHIC presents many unique features and challenges. An accurate estimate of the cooling times requires a detailed calculation of the cooling process, which takes place simultaneously with various diffusive mechanisms in RHIC. In addition, many unexplored effects of highenergy cooling in a collider complicate the task of getting very accurate estimates of cooling times. To address these highenergy cooling issues, a detailed study of cooling dynamics based on computer codes is underway at Brookhaven National Laboratory. In this paper, we present an update on code development and its application to the highenergy cooling dynamics studies for RHIC. 

TPAT091  IBS for Ion Distribution Under Electron Cooling  4263 


Funding: Work supported by the U.S. Department of Energy under contract No. DEAC0298CH10886.
Standard models of the intrabeam scattering (IBS) are based on the growth of the rms beam parameters for a Gaussian beam distribution. As a result of electron cooling, the core of beam distribution is cooled much faster than the tails, producing a denser core. Formation of such a core is an important feature since it plays dominant role in the luminosity increase. A simple use of standard rmsbased IBS approach may significantly underestimate IBS for the beam core. A detailed treatment of IBS, which depends on individual particle amplitudes, was recently proposed by Burov,* with an analytic formulation done for a Gaussian distribution. However, during the cooling process the beam distribution quickly deviates from a Gaussian profile. To understand the extent of the dense core formation in the ion distribution, the "coretail" model for IBS, based on the diffusion coefficients for biGaussian distributions, was employed in cooling studies for RHIC. In addition, the standard IBS theory was recently reformulated for rms parameters growth of a biGaussian distribution by Parzen.** In this paper, we compare various approaches to IBS treatment for such distribution. Its impact on the luminosity is also discussed.
*A. Burov, FERMILABTM2213 (2003). **G. Parzen, Tech Note CAD/AP/150 (2004). 

TPAT092  Numerical Studies of the Friction Force for the RHIC Electron Cooler  4278 


Funding: Work performed under the auspices of the U.S. Department of Energy.
Accurate calculation of electron cooling times requires an accurate description of the dynamical friction force. The proposed RHIC cooler will require ~55 MeV electrons, which must be obtained from an RF linac, leading to very high transverse electron temperatures. A strong solenoid will be used to magnetize the electrons and suppress the transverse temperature, but the achievable magnetized cooling logarithm will not be large. Available formulas for magnetized dynamical friction are derived in the logarithmic approximation, which is questionable in this regime. In this paper, we explore the magnetized friction force for parameters of the RHIC cooler, using the VORPAL code.* VORPAL can simulate dynamical friction and diffusion coefficients directly from first principles.** Various aspects of the friction force, such as dependence on magnetic field, scaling with ion charge number and others, are addressed for the problem of highenergy electron cooling in the RHIC regime.
*C. Nieter & J.R. Cary, J. Comp. Phys. 196 (2004), p. 448. **D.L. Bruhwiler et al., Proc. 33rd ICFA Advanced Beam Dynamics Workshop (2004). 

TPAT093  Operations and Performance of RHIC as a CuCu Collider  4281 


Funding: Work performed under the auspices of the U.S. Department of Energy. The 5th year of RHIC operations, started in November 2004 and expected to last till June 2005, consists of a physics run with CuCu collisions at 100 GeV/u followed by one with polarized protons at 100 GeV. We will address here overall performance of the RHIC complex used for the first time as a CuCu collider, and compare it with previous operational experience with Au, PP and asymmetric dAu collisions. We will also discuss operational improvements, such as a ?* squeeze to 85cm in the high luminosity interaction regions from the design value of 1m, system improvements and machine performance limitations, such as vacuum pressure rise, intrabeam scattering, and beam beam interaction. 

TPAT094  Luminescence Beam Profile Monitor for the RHIC Polarized Hydrogen Jet Polarimeter  4293 


Funding: Work performed under Contract Number DEAC0298CH10886 with the auspicies of the US Deparment of Energy. This is the second polarized proton run in Relativistic Heavy Ion Collider (RHIC) with a new polarized proton jet target used to provide accurate polarization measurements. The interactions between the stored polarized protons with the polarized jet target will produce, in addition to polarization, optical signals due to exited states of Hydrogen or other molecules, ions, or atoms. Additional lenses, optical window, optical analyzer, and the CCD camera are added to the system to allow transfer and detection of optical signals from the interaction chamber. Oxygen or other elements (impurities) could be mixed within the jet target and affect the accuracy of the polarization measurements. It is important to have continuous information of the jet content without affecting the polarization measurements. The optical signals coming from the exited states of molecules, ions, and atoms from the polarized proton beam interaction with the jet will provide that. In addition, the beam profile might be obtained. 

TPAT095  Beam Induced Pressure Rise at RHIC  4308 


Beam induced pressure rise in RHIC warm sections is currently one of the machine intensity and luminosity limits. This pressure rise is mainly due to electron cloud effects. The RHIC warm section electron cloud is associated with longer bunch spacings compared with other machines, and is distributed nonuniformly around the ring. In addition to the countermeasures for normal electron cloud, such as the NEG coated pipe, solenoids, beam scrubbing, bunch gaps, and larger bunch spacing, other studies and beam tests toward the understanding and counteracting RHIC warm electron cloud are of interest. These include the ion desorption studies and the test of antigrazing ridges. For high bunch intensities and the shortest bunch spacings, pressure rises at certain locations in the cryogenic region have been observed during the past two runs. Beam studies are planned for the current 2005 run and the results will be reported.
Work performed under the auspices of the US Department of Energy. 

TPAT096  FocusingFree Transition Crossing in RHIC using Induction Acceleration  4314 


Focusingfree transition crossing (FFTC) in RHIC is proposed. The original idea of FFTC proposed by J.Griffin was tried in the FNAL 500GeV main ring, where a gradient in the acceleration voltage was smoothed flat by introducing multi higherharmonic RF. If the longitudinal focusing disappears during a limited time period near TC, various undesired features, such as bunch shortening and elongation in the momentum space, should be mitigated. In present RHIC operation, the slow ramping across transition leads into complications of nonlinear chromatic effects, vacuum pressure rise, instability, and transitionjump related lattice distortions. Recently, induction acceleration of a single RF bunch has been successfully demonstrated in KEKPS,* where a proton bunch is trapped by the existing RF and accelerated with an induction stepvoltage to 8 GeV. The utilized acceleration device is capable of generating a step voltage of 2 kV/cell at most at an arbitrary repetition rate up to 1 MHz. We here propose focusingfree TC in RHIC, introducing similar devices. In this scheme, the RF voltage is tuned off during an optimized timeperiod of several tens of ms, and the required acceleration voltage is provided as an induction flatvoltage.
*K.Takayama et al., submitted to Phys. Rev. Lett., http://www.arxiv.org/pdf/physics/0412006. 

TPAT097  CLIC Drive Beam and LHC Based FELNucleus Collider  4320 


Funding: Ankara University, Ankara, TURKEY. Main parameters of CLICLHC based FELNucleus collider are determined. The matching of beam structures for maximum luminosity is studied. The advantages of the collider with respect to the traditional Nuclear Resonance Fluorescence (NRF) methods are presented considering (/Gamma/Gamma^{}(prime)) reactions. Determination of unknown decay width, spin and parity of excited levels is discussed for Pb nucleus. 

TPAT098  A Review of TeV Scale LeptonHadron and PhotonHadron Colliders  4329 


Funding: Gazi University, Ankara, Turkey. The investigation of leptonhadron and photonhadron collisions at TeV scale is crucial both to clarify the strong interaction dynamics from nuclei to quarkparton level and for adequate interpretation of experimental data from future hadron colliders (LHC and VLHC). In this presentation different TeV scale leptonhadron and photonhadron collider proposals (such as THERA, "LEP"LHC, QCD Explorer etc) are discussed. The advantages of linacring type colliders has been shown comparatively. 

TPAT099  Main Parameters of ILCTevatron Based LeptonHadron and PhotonHadron Colliders  4335 


Funding: Ankara University. The construction of the ILC tangential to Tevatron ring will give opportunity to investigate electronproton, positronproton, electronantiproton, positronantiproton interactions at 1 TeV center of mass energy. The analysis of the leptonhadron collisions in these energy region is very important both for understanding of strong interaction dynamics and for adequate interpretation of future LHC and VLHC data. In addition, ILCTevatron collider will provide a possibility to realize photonhadron collisions in the same energy region using Compton backscattered laser photon of ILC electron beam. Main parameters of these colliders are estimated and their physics search potential is briefly discussed. 