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MOYCH03 Superconducting RF Cavities for Synchrotron Light Sources damping, extraction, impedance, hadron 21
 
  • P. Marchand
    SOLEIL, Gif-sur-Yvette
  Superconducting (sc) RF systems are already operational or planned in several third generation synchrotron light sources. In these machines, which require relatively low RF accelerating voltage and high beam loading, the advantage of using the sc technology essentially resides in the fact that one can achieve an efficient damping of the cavity Higher Order Modes (HOM) while still maintaining a high fundamental shunt impedance. The strong HOM damping practically is realised following two approaches : a) use of absorber material, located inside the cavity tube cut-off, through which the HOM propagate and then are damped (Cornell/KEK designs); b) two-cell cavity with coaxial HOM dampers located on the tube connecting the two cells (SOLEIL design). Third harmonic idle sc cavities (1.5 GHz) of the SOLEIL type are already operational in the Swiss Light Source and ELETTRA. The main RF system (500 MHz) of these machines consist of normal conducting cavities and the purpose of the third harmonic sc system is to lengthen the bunches in order to improve the beam lifetime and stability (additional Landau damping). Recently, several third generation synchrotron light sources have also planned to use sc cavities as main accelerating RF systems. The operational conditions of the existing systems as well as the status of the planned ones are reported here.  
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MOZCH01 Technologies for Electron-positron Linear Colliders damping, collider, extraction, impedance 26
 
  • S.D. Holmes
    Fermilab, Batavia, Illinois
  High energy electron-positron Linear Collider designs based on room temperature and superconducting technologies have been developed and are currently under consideration by the International Technology Recommendation Panel. This paper will review the requirements and state of development of technologies required to support a linear collider meeting the performance goals outlined by the world high energy physics community. In addition it will summarize the cold/warm comparative study completed in the U.S. with particular emphasis on unique aspects related to availability and risk analysis.  
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MOZCH02 Start to End Simulations of Low Emittance Tuning and Stabilization simulation, collider, emittance, damping 31
 
  • P. Tenenbaum, A. Seryi, M. Woodley
    SLAC, Menlo Park, California
  • D. Schulte
    CERN, Geneva
  • N.J. Walker
    DESY, Hamburg
  • G.R. White
    Queen Mary University of London, London
  The principal beam dynamics challenge to the subsystems between the damping ring and the collision point of future linear colliders is expected to be the tuning and stabilization required to preserve the transverse emittance and to collide nanometer-scale beams. Recent efforts have focused on realistically modelling the operation and tuning of this region, dubbed the Low Emittance Transport (LET). We report on the development of simulation codes which permit integrated simulation of this complex region, and on early results of these simulations. Future directions of LET simulation are also revealed.  
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MOOCH01 Beam Based Alignment at the KEK-ATF Damping Ring simulation, damping, alignment, emittance 36
 
  • M. Woodley, J. Nelson, M.C. Ross, J.L. Turner
    SLAC, Menlo Park, California
  • K. Kubo
    KEK, Ibaraki
  • A. Wolski
    LBNL/AFR, Berkeley, California
  The damping rings for a future linear collider will have demanding alignment and stability requirements in order to achieve the low vertical emittance necessary for high luminosity. The Accelerator Test Facility (ATF) at KEK has successfully demonstrated the <5 pm vertical emittance specified for the GLC/NLC Main Damping Rings [*]. One contribution to this accomplishment has been the use of Beam Based Alignment (BBA) techniques. The mode of operation of the ATF presents particular challenges for BBA, and we describe here how we have deduced the offsets of the BPMs with respect to the quadrupoles. We also discuss a technique that allows for direct measurements of the beam-to-quad offsets.

* "Extremely Low Vertical-Emittance Beam in the Accelerator Test Facility at KEK", K. Kubo, et al., Phys.Rev.Lett.88:194801,2002

 
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TUZACH01 Positron Source Options for Linear Colliders gun, positron, focusing, acceleration 69
 
  • K. Floettmann
    DESY, Hamburg
  Linear colliders require sources delivering particle intensities much higher than sources for storage rings and even several orders of magnitude larger than the SLC positron source, the highest intensity positron source operated so far. A fundamental limitation for the intensity of a positron source is set by the thermal stress in the target. Besides improvements of conventional positron sources, i.e. sources where an electron beam creates electron position pairs in an electromagnetic cascade, new concepts based on the direct conversion of gamma radiation offer possibilities for increased particle intensities. In these sources the hard gamma radiation has to be produced either in an undulator or by backscattering of laser light off an electron beam. An additional advantage of gamma radiation based sources is the possibility to produce polarized positrons. The talk will give an overview of the developments of high intensity unpolarized and polarized positron sources for linear colliders.  
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TUZBCH01 Beam Quality Preservation in the CERN PS-SPS Complex gun, positron, focusing, plasma 78
 
  • G. Arduini
    CERN, Geneva
  The LHC will require beams of unprecedented transverse and longitudinal brightness. Their production imposes tight constraints on the emittance growth in each element of the LHC injector chain, namely the PS-SPS Accelerator Complex. The problems encountered at the different stages of the acceleration in the complex span a wide range of topics, such as injection matching, RF gymnastics, space charge, transverse and longitudinal single- and coupled-bunch instabilities, and electron cloud effects. The measurement techniques developed and applied to identify and study the various sources of emittance dilution to the high precision required for the LHC beams and the solutions found to control such phenomena are illustrated.  
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TUZBCH02 Beam Dynamics Challenges for Future Circular Colliders gun, positron, focusing, plasma 83
 
  • F. Zimmermann
    CERN, Geneva
  The luminosity of circular colliders rises with the beam intensity, until some limit is encountered, mostly due to head-on and long-range beam-beam interaction, due to electron cloud, or due to conventional impedance sources. These limitations can be alleviated, if not overcome, by a proper choice of beam parameters and by dedicated compensation schemes. Examples include the alternating crossing at several interaction points, electromagnetic wires, super-bunches, electron lenses, clearing electrodes, and nonlinear collimation. I illustrate the benefit from such mitigating measures for the Tevatron, the LHC, the LHC Upgrade, the VLHC, the super e+e- factories, or other projects, and I describe related research efforts at FNAL, KEK, BNL and CERN.  
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TUXLH01 Machine Protection Issues and Strategies for the LHC gun, positron, focusing, plasma 88
 
  • R. Schmidt, J. Wenninger
    CERN, Geneva
  For nominal beam parameters at 7 TeV/c, each of the two LHC proton beams has a stored energy of 350 MJ threatening to damage accelerator equipment in case of uncontrolled beam loss. Since the beam dump blocks are the only element of the LHC that can withstand the impact of the full beam, it is essential for the protection of the LHC that the beams are properly extracted onto the dump blocks in case of emergency. The time constants for failures leading to beam loss extend from 100 microseconds to few seconds. Several protection systems are designed to ensure safe operation, such as beam instrumentation, collimators and absorbers, and magnet protection. Failures must be detected at a sufficiently early stage and transmitted to the beam interlock system that triggers the beam dumping system. The strategy for the protection of the LHC will be illustrated starting from some typical failures.  
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TUYLH02 Low and Medium Energy Beam Acceleration in High Intensity Linacs gun, positron, focusing, plasma 108
 
  • J. Stovall
    LANL, Los Alamos, New Mexico
  In the past two years accelerator builders have published papers describing mature designs of no fewer than 7 new high-performance proton linacs. These machines are typically designed to deliver multi-megawatt beams for applications in pure and applied research. All of these machines use the radio-frequency quadrupole (RFQ) linac for the first stage of acceleration to reach an energy of a few MeV. In essentially all cases, superconducting elliptical cavities have been adopted as the technology of choice for acceleration above ~100 MeV. Between the RFQ and the high-energy elliptical cavities, designers have proposed no fewer than 6 different types of accelerating structures. In many cases these structures are reaching maturity as a result of active development programs. In this paper, we review the design architectures of the ?low and medium energy? portions of these machines emphasizing recent experience and developments applicable to high-current linac designs.  
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TUPLT075 Improvements of SPring-8 Linac towards Top-up Operation booster, laser, beamloading, antiproton 1327
 
  • S. Suzuki, T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, T. Masuda, A. Mizuno, T. Taniuchi, H. Tomizawa, K. Yanagida
    JASRI/SPring-8, Hyogo
  The top-up operation of the SPring-8 storage ring will start in May, 2004. In order to realize alternative injection into the booster synchrotron in the top-up operation and the NewSUBARU, an AC bending magnet replaced the DC bending magnet in the beam transport line to the booster synchrotron. This magnet operates at 1 Hz with a trapezoid current pattern. The 1-GeV electron beam goes at the bottom of the current pattern to the NewSUBARU or at the top of the pattern to the booster synchrotron. In order to obtain the higher reliability of the linac for the top-up operation, reinforcement of the beam monitor systems, further improvement of RF phase stability and upgrade of the control system were required. BPM?s has been newly installed in energy dispersion sections, and beam transport feedback control is in development. The phase variation in the RF system was reduced by the regulation of the gas pressure in the waveguide of the klystrons drive system. We re-engineered the VME systems to maximize availability of the linac operation considering its reliability, usability, expandability and flexibility.  
 
TUPLT076 Optimization of Sextupole Strengths in a Storage Ring for Top-up Operation sextupole, injection, booster, laser 1330
 
  • H. Tanaka, T. Ohshima, K. Soutome, M. Takao, H. Takebe
    JASRI/SPring-8, Hyogo
  In top-up operation of a light source, electron or positron beams are frequently injected to keep the stored current constant. Closing an injection bump orbit is thus critically important not to disturb precise experiments. However, there are sextupole magnets inside the injection bump in the SPring-8 storage ring and the bump never closes all over the bump amplitude due to the sextupole nonlinearity. To solve the problem, we proposed a scheme based on minimum condition for the injection bump leakage. The scheme only restricts the sextupole strengths within the bump. Introduction of other sextupole families outside the bump can enlarge the dynamic aperture (DA) of the ring with keeping the minimum leakage. To find the best solution, we optimized the sextupole strengths changing the number of sextupole family as a parameter. The simulation shows that addition of two sextupole families sufficiently enlarges DA. Cabling of the sextupole magnets was partly changed in the summer 2003 and the effects of the strength optimization on the bump leakage, injection efficiency and beam lifetime has been investigated experimentally. We present the obtained results compared with the simulations.  
 
WEPLT053 Dynamical Effects of the Montague Resonance focusing, bunching, impedance, optics 1957
 
  • I. Hofmann, G. Franchetti
    GSI, Darmstadt
  • J. Qiang, R.D. Ryne
    LBNL/CBP, Berkeley, California
  In high-intensity accelerators emittance coupling, known as Montague resonance, may be an issue if the tune split is small. For static tunes within the stop-band of this fourth order space charge driven coupling the final emittances may become equal (equipartition). Using 2D computer simulation we show, however, that slow crossing of the resonance leads to merely an exchange of emittances. In 3D this is similar, if the crossing occurs over a time-scale shorter or comparable with a synchrotron period. For much slower crossing we find, instead, that the exchange may be suppressed by synchrotron motion. We explain this effect in terms of the mixing caused by the synchrotron motion.  
 
WEPLT054 Electron Cloud Build up in Coasting Beams focusing, bunching, impedance, optics 1960
 
  • G. Rumolo
    GSI, Darmstadt
  • G. Bellodi
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • K. Ohmi
    KEK, Ibaraki
  • F. Zimmermann
    CERN, Geneva
  Electrons could in principle accumulate in the potential of coasting beams of positively charged particles until a balance between the beam force and space charge force from the electrons is reached. But the continuous interaction between a non-ideal perturbed coasting beam and the cloud of electrons being trapped by it, together with the reflection and secondary emission processes at the inner pipe wall, can alter this picture and cause a combined cloud or beam transverse instability long before the concentration of electrons reaches the theoretical equilibrium value. The issue is addressed in this paper by means of combined build-up and instability simulations carried out with the HEADTAIL code.  
 
THOBCH01 The Beijing Electron-positron Collider and its Second Phase Construction collider, injection, radiation, wakefield 230
 
  • C. Zhang, J.Q. Wang
    IHEP Beijing, Beijing
  The Beijing Electron-Positron Collider (BEPC) was constructed for both high energy physics and synchrotron radiation researches. As an e+e- collider operating in the tau-charm region and a first synchrotron radiation source in China, the machine has been well operated for 14 years since it was put into operation in 1989. As a collider, the peak luminosity of the BEPC has reached its design goal of 5*1030 cm-2s-1 at J/sai energy of 1.55 GeV and 1*1031 cm-2s-1 at 2 GeV respectively. The main parameters in the dedicated synchrotron radiation operation are: E=2.2~2.5 GeV, ex0=80 mm mrad at 2.2 GeV, Ib=140 mA and the beam lifetime of 20~30 hours. As the second phase project of the BEPC, the BEPCII , has been approved with total budget of 640 million RMB. The construction is started in the beginning of 2004 and is scheduled to complete by the end of 2007. The BEPCII is a double ring machine with its luminosity goal of 1*1033 cm-2s-1 at 1.89 GeV, two orders of magnitude higher than present BEPC. The BEPCII will operate in the beam energy of 1-2.1 GeV so that its physical potential in the whole t and charm range is preserved, while the collider will be optimized at 1.89 GeV. The upgrading of the collider should also provide an improved SR performance with higher beam energy and intensity. The beam currents will be increased to 250 mA at E=2.5 GeV for the dedicated synchrotron radiation operation of the BEPCII. Some key technologies, such as superconducting RF system, low impedance vacuum devices, superconducting micro-beta quadrupoles and etc., has been intensively studied in order to achieve the target of the BEPCII.  
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THOBCH02 DAFNE Operation with the FINUDA Experiment injection, radiation, wakefield, beamloading 233
 
  • C. Milardi, D. Alesini, G. Benedetti, M.E. Biagini, C. Biscari, R. Boni, M. Boscolo, A. Clozza, G.O. Delle Monache, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, G. Mazzitelli, L. Pellegrino, M.A. Preger, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, C. Vaccarezza, M. Vescovi, M. Zobov
    INFN/LNF, Frascati (Roma)
  DAFNE operation restarted in September 2003, after a six months shut-down for the installation of FINUDA, a magnetic detector dedicated to the study of hypernuclear Physics. FINUDA is the third experiment running, in sequence, at DAFNE and operates while keeping on place the other detector KLOE. During the shut-down both the Interaction Regions have been equipped with remotely controlled rotating quadrupoles in order to operate at different solenoid fields. Among many other hardware upgrades one of the most significant is the reshaping of the wiggler pole profile to improve the field quality and the machine dynamic aperture. Commissioning of the collider in the new configuration has been completed in short time. The peak luminosity delivered to FINUDA has reached 6 1031 s-1 cm-2, with a daily integrated value exceeding 3 pb-1.

Work presented by C. Milardi on behalf of the DAFNE Team

 
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THOBCH03 Barrier RF Systems in Synchrotrons injection, radiation, wakefield, beamloading 236
 
  • C.M. Bhat
    Fermilab, Batavia, Illinois
  Recently, the barrier bucket techniques have been used in many interesting applications in proton synchrotrons around the world. Specially designed broad-band rf cavities are used to generate barrier buckets. At Fermilab we have barrier RF systems in four different rings and have used them for various beam gymnastics. Particularly, in the case of Fermilab Recycler Ring, all rf manipulations required during beam cooling, beam stacking and unstacking are carried out using barrier buckets. Also, we have explored new methods for increasing the beam intensities in the Main Injector. Here, I review various uses of barrier rf system in particle accelerators and possible new applications.  
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THZCH01 Status of Tevatron Collider Run II and Novel Technologies for the Tevatron Luminosity Upgrades injection, radiation, wakefield, beamloading 239
 
  • V.D. Shiltsev
    Fermilab, Batavia, Illinois
  In the Tevatron Run-II, 36 antiproton bunches collide with 36 proton bunches at the CDF and D0 interaction regions at 980 GeV per beam. We present current status and performance of the collider complex. The plan for Run-II luminosity upgrades will be presented and novel technologies for the upgrade will be discussed.  
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THZCH02 Electron Cooling: Remembering and Reflecting injection, radiation, electron, wakefield 244
 
  • I.N. Meshkov
    JINR, Dubna, Moscow Region
  The report contains a brief review of developments in electron cooling methods. The influence of electron cooling concepts on progress in particle beam physics is considered, particularly: development of alternative and complementary cooling methods - stochastic, laser, muon cooling; physics of cooled and intense particle beams; ordering effects in cooled ion beams and the idea of crystalline beams; intrabeam scattering in cooled beams, etc. Creation of new accelerator technology, based on electron cooling and its application to different fields of experimental physics, particle, nuclear and atomic physics, is described. Modern trends and new concepts of electron cooling applications are discussed.  
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THZCH03 JACoW, a Collaboration Serving the Accelerator Community injection, radiation, electron, wakefield 249
 
  • J. Poole, C. Petit-Jean-Genaz
    CERN, Geneva
  The Joint Accelerator Conferences Website started from an idea to publish the conference proceedings on the WWW and has grown to an international collaboration which does much more than just publish the proceedings and is currently supported by seven conference series. Through attendance at Steering Committee meetings and Team Meetings and through active participation in the work of the editorial teams of sister conferences, people with the responsibility for the production of the electronic versions of conference proceedings come together to learn from the experience of colleagues, and to develop common approaches to problems. The activities of the collaboration cover all aspects of electronic publication and have recently extended into conference scientific programme management. This paper reviews the history of the collaboration, describes some of the highlights in the activities during the life of the collaboration and presents the current status and future plans.  
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THOALH01 Bunch Length Measurements at the SLS Linac using Electro-optical Techniques laser, injection, wakefield, electron 253
 
  • A. Winter, M. Tonutti
    RWTH, Aachen
  • S. Casalbuoni, P. Schmüser, S. Simrock, B. Steffen
    DESY, Hamburg
  • T. Korhonen, T. Schilcher, V. Schlott, H. Sigg, D. Suetterlin
    PSI, Villigen
  The temporal profile of the electron bunches in the SLS Linac will be determined by means of electro-optical techniques. A mode locked Ti:Sa Laser with 15 fs pulse width is used for coincidence measurements between the laser pulse and the coherent transition radiation (CTR) generated by short electron bunches. Synchronization accuracy of 100 fs rms between the 3 GHz Linac RF and the 81 MHz repetition rate of the laser was achieved, which is important for the optimum time resolution of the applied electro-optical sampling technique. Likewise, a mode locked Nd:YAG laser with 400 ps long pulses will be used for electro-optical autocorrelation measurements between the CTR and the laser pulses. This alternative technique promises single shot capability and requires much relaxed synchronization stability between laser and electron beam.  
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THPKF018 Study for a Frequent Injection Mode at Delta with Beam Shutters Open injection, wakefield, beamloading, lattice 2296
 
  • G. Schmidt, M. Benna, U. Berges, J. Friedl, A. Gasper, M. Grewe, P. Hartmann, R.G. Heine, H. Huck, D. Schirmer, S. Strecker, T. Weis, K. Wille, N. Zebralla
    DELTA, Dortmund
  The Dortmunder Electron Accelerator (DELTA) is a 1.5 GeV synchrotron light source. DELTA is now operated for 3000 h per year including 2000 h beam time for synchrotron radiation use. The maximum beam current is limited by rf power. To increase the average beam current a frequent injection scheme with beam shutters open is discussed for Delta. The peak current is not enlarged but the number of injections is increased to establish a quasi constant beam current. The quasi constant beam current has in addition the advantage of a constant synchrotron radiation heat-load on vacuum chambers and experiments. First tests at Delta have shown the gain in stability of the closed orbit during frequent injection. This article shows the possibility to install a frequent injection mode with beam shutters open during injection at DELTA. The results of measurements and simulations are presented.  
 
THPKF019 PETRA III: A New High Brilliance Synchrotron Radiation Source at DESY injection, wakefield, emittance, beamloading 2299
 
  • K. Balewski, W. Brefeld, W. Decking, Y.L. Li, G.K. Sahoo, R. Wanzenberg
    DESY, Hamburg
  DESY has decided to rebuild its 2304 m long accelerator PETRA II into a dedicated light source called PETRA III. The reconstruction is planned to start mid of 2007.The new light source will operate at an energy of 6 GeV, a current of 100 mA, a horizontal emittance of 1 nmrad and an emittance coupling of 1%. In the first phase thirteen insertion devices are foreseen. In this paper the principle layout of the machine will be presented. The structure of the new machine combines properties of conventional storage rings and light sources and is therefore quite unconventional. One of the major challenges of the project is to achieve the small emittances. The basic idea is to use so called damping wigglers with a total length of 80 m to reduce the horizontal emittance to the desired level. To obtain and maintain the small emittances imposes tight tolerances on spurious dispersion and orbit quality and stability. These limits will be given and discussed.  
 
THPKF027 A Concept for the Spanish Light Source CELLS beamloading, lattice, beamlosses, impedance 2323
 
  • D. Einfeld, J. Bordas, J. Campmany, S. Ferrer, M. Muñoz, M. Pont, F. Pérez
    CELLS, Bellaterra (Cerdanyola del Vallès)
  In May of 2003 the Spanish and Catalan Governments established a public Consortium for the construction, equipment and exploitation of a third generation Synchrotron Light Source. The foundation was based upon a proposal from 1997 to build a 2.5 GeV, 12-fold symmetry machine with a circumference of around 260 m. At present a re-design is being considered, based upon the following decisions: 1.) Electron energy of 3 GeV, 2.) Circumference around 280 m, 3.) Emittance smaller than 5 nm.rad, 4.) 16-fold symmetry lattice 5.) Full energy injector, 6.) Topping-up injection mode foreseen and 7.) Booster synchrotron and Storage ring housed in the same tunnel. Lattice considerations are given in an accompanying paper. In the present one we will give a project overview and explain key design decisions and overall schedule. Five beamlines will be design and construct in a first phase to cover the needs of the Spanish community. The definition of these beamlines will take place during 2004 involving the users community. Planned beam commissioning will be in 2009.  
 
THPKF035 Design of the Super-SOR Light Source target, booster, beamloading, damping 2347
 
  • N. Nakamura
    ISSP/SRL, Chiba
  The Super-SOR light source is a Japanese VUV and soft X-ray third-generation synchrotron radiation source, which is to be operated for nation-wide and world-wide users. The University of Tokyo has proposed to construct the facility in Kashiwa new campus and we have designed the light source intensively for more than two years. The light source consists of an electron storage ring, booster synchrotron and pre-injector linac. The 1.8-GeV storage ring has a circumference of about 280 m and 14 DBA cells with two 17-m and twelve 6.2-m long straight sections, which are used for twelve insertion devices and RF and injection systems. The booster synchrotron is compact, one third of the ring in circumference, and can achieve a low emittance of about 50 nmrad at 1.8 GeV. The 200-MeV linac is made up of S-band accelerating structures powered by two 50-MW klystrons and a SLED cavity and capable of changing the beam current widely in both single- and multi-bunch operation modes. These accelerators are designed so as to fully meet requirements for top-up injection. We describe the design of the Super-SOR accelerators here.

on behalf of the Super-SOR accelerator design group

 
 
THPLT038 The Synchrotron Radiation Interferometer using Visble Light at DELTA antiproton, ion, positron, simulation 2562
 
  • U. Berges, K. Wille
    DELTA, Dortmund
  Synchrotron radiation sources such as DELTA, the Dortmund electron accelerator, rely on a monitoring system to measure the beam size and emittance with sufficient resolution. The resolution limits of the different types of optical synchrotron light monitors at DELTA have been investigated. The minimum measurable beam size with the standard synchrotron light monitor using visible light at DELTA is appr. 80 μm. Due to this limitation an interferometer was built up and tested using the same beamline in the visible range. A minimum measurable beam size of appr. 8 μm could be obtained, which gives an increased resolution of one order of magnitude with the new system.  
 
THPLT039 SVD Based Orbit Correction Incorporating Corrector Limitations at DELTA antiproton, ion, positron, simulation 2565
 
  • M. Grewe, P. Hartmann, G. Schmidt, K. Wille
    DELTA, Dortmund
  Singular Value Decompostion (SVD) of the orbit response matrix has become an invaluable tool for orbit correction at storage rings worldwide. SVD based orbit correction has now been realised at DELTA, a 1.5 GeV electron storage ring. However, due to special orbit demands at DELTA and possibly by magnetic imperfections within the storage ring, we frequently have to face corrector limitations during the process of orbit correction. This work focuses on presenting an analytic algorithm on how to treat these limitations when seeking for an optimal SVD based orbit correction. In contrast to previously published methods, this approach is fairly easy to implement and does not afford an numerical solver. Concepts and results will be presented.  
 
THPLT041 Beam Test Stand of the RFQ-drifttube-combination for the Therapy Center in Heidelberg antiproton, positron, simulation, lattice 2568
 
  • A. Bechtold, M. Otto, U. Ratzinger, A. Schempp, E. Vassilakis
    IAP, Frankfurt-am-Main
  • B. Schlitt
    GSI, Darmstadt
  A beam test stand for the Heidelberg medicine RFQ has been installed at the IAP in Frankfurt. The installation consists of a 8 keV/u H+ duoplasmatron ion source, the 400 keV/u RFQ itself and several diagnostic elements comprising a slit-grid emittance measurement system for scanning the transverse beam profile and a bending magnet for measuring the longitudinal beam properties. The test installation will be described in detail, first measurements will be presented and compared to corresponding beam dynamic simulations.  
 
THPLT042 Automated Orbit Control for the HERA ep Collider antiproton, positron, simulation, lattice 2571
 
  • S.W. Herb, P.K. Bartkiewicz, F. Brinker, J.M. Maass
    DESY, Hamburg
  Successful operation of the HERA electron-proton collider requires maintaining stable orbits during the typically 12 hour luminosity runs, as well as during the fill and acceleration procedures. The primary sources of orbit errors for the electron ring are the interaction region magnets, whose support structures are integrated with the experimental detectors and susceptible to thermal and magnetic effects. The orbit correction algorithms are designed to correct these effects locally, while operating with somewhat reduced sensitivity on error sources in the rest of the ring. We describe the correction system and our operating experience.  
 
THPLT043 Development of a New Orbit Measurement System antiproton, positron, simulation, lattice 2574
 
  • O. Kaul, F. Brinker, R. Neumann, R. Stadtmüller
    DESY, Hamburg
  Since DORIS III became a dedicated source for synchrotron radiation in 1993, the demands of the synchrotron-light-users concerning the beam position stability have permanently increased.In order to improve this stability, different measures have been adopted, all with success. The vacuum chambers have been renewed, since they were the source of quadrupole movement, which caused strong horizontal orbit distortion. In 2003 a new orbit position control was implemented, based on the ?Singular Value Decomposition? method. The position information comes from synchrotron light monitors, installed in the beam-lines, and from the orbit measurement system, which operates with a maximal measurement rate of 5Hz and a spatial resolution not less than 20μm. To satisfy the requirements for beam-position stability, the orbit measurement system has been further developed. The test stage is nearly finished and the new system will be installed soon. The orbit measurement rate will exceed 250Hz und the spatial resolution will be less than 2μm. In addition beam oscillations of up to 20Hz can be damped.  
 
THPLT044 Measurement of the Transverse Coherence of the TTF Free Electron Laser antiproton, undulator, positron, radiation 2577
 
  • R. Ischebeck, M. Tonutti
    RWTH, Aachen
  • J. Feldhaus, E. Saldin, E. Schneidmiller, K. Tiedtke, R. Treusch
    DESY, Hamburg
  • C. Gerth
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. Schmüser
    Uni HH, Hamburg
  • M.V. Yurkov
    JINR, Dubna, Moscow Region
  The transverse coherence is important for many applications of a free electron laser (FEL). It depends on the inner structure of the electron bunch in the undulator, which is difficult to measure. It is therefore essential to determine the coherence properties of the FEL radiation directly. The coherence of the vacuum ultraviolet FEL at the TESLA Test Facility has been measured by recording the diffraction pattern of a double slit and measuring the visibility of the interference fringes. The experimental near field diffraction pattern is compared with a numerical model, taking into account the formation of the FEL radiation, the Fresnel diffraction in the near field zone and effects of the experimental set-up. Diffraction patterns have been recorded at various undulator lengths to measure the evolution of the transverse coherence along the undulator. This is compared to the expected evolution of the transverse radiation modes.  
 
THPLT045 A more Accurate Approach to Calculating Proton Bunch Evolution under Influence of Intra-beam Scattering in a Storage Ring. antiproton, undulator, positron, radiation 2580
 
  • I.V. Agapov, F.J. Willeke
    DESY, Hamburg
  Some perturbations of discrete nature are known to influence the performance of a proton storage ring, contributing to parasitic background, decay of beam currents and bunch tail buildup. Such are, for example, intra-beam scattering and residual gas scattering .These processes are to a big extent described by existing analytical theory. The latter, employing a large amount of averaging, usually neglects effects arising from system nonlinearity. So, the motion of tail particles in the presence of a sufficiently nonlinear RF voltage under influence of intra-beam scattering strongly deviates from the average across the bunch and the analytical approach seems inadequate for it. To overcome this situation we have developed more accurate numerical methods for calculations of bunch evolution under influence of a rather broad class of jump-like perturbations. Here we present the computational algorithms and their application to assessment of coasting beam and proton background in HERA-p.