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emittance

                          
Paper Title Other Keywords Page
MO204 Status of REX-ISOLDE ion, linac, injection, target 18
 
  • O.K. Kester, S. Emhofer, D. Habs, K. Rudolph
    LMU, Garching
  • F. Ames, P. Butler, P. Delahaye, M. Lindroos, T. Sieber, F.J.C. Wenander
    CERN, Geneva
  • R. Repnow, H. Scheit, D. Schwalm, R. von Hahn
    MPI-K, Heidelberg
  After commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) first series of physics experiments in 2002 and 2003 have been performed. The REX-ISOLDE charge state breeder adjusts the charge-to-mass ratio of isotopes from all over the nuclear chart to the LINAC requirements. A variety of isotopes from different mass regions of the nuclear chart have been charge bred with REXEBIS to the required A/q < 4.5. A variety of tests with REXTRAP, REXEBIS and the LINAC structures have been done, in order to study the beam parameters, transmission efficiency and upgrade options. The LINAC now consists of six resonators and one re-buncher cavity. The beam energy, which can be delivered towards the target areas, can be varied between 0.8 and 2.2. An additional boost to 3 MeV/u is now possible because of the upgrade with a 202.56 MHz IH-cavity developed for the MAFF project. In addition experiment using beams from the RFQ at 0.3 MeV/u have been performed for solid state physics experiments. The present status of the projects and the commissioning measurements will be presented.  
Transparencies
 
MO301 SPIRAL2 at GANIL ion, rfq, linac, ion-source 23
 
  • M.-H. Moscatello
    GANIL, Caen
  The detailed design study phase of the SPIRAL2 project has been launched since beginning of 2003. The aim of this facility is to produce rare ion beams, using a Uranium carbide target fission process, based on a fission rate of 1013 to 1014 fissions/s. The driver accelerator accelerates a 5 mA deuteron beam up to 20 MeV/u, impinging on a carbon converter to produce the neutrons necessary to the fission process. It has also to accelerate q/A=1/3 heavy ions, to energies between 0.75 and 14.5 MeV/A for different types of nuclear and non-nuclear physics experiments. The accelerator, based on a RFQ followed by an independently phased superconducting cavity linac with warm focusing sections, is under design. This paper presents the reference design chosen for SPIRAL2 driver accelerator and gives the design status of the different components: Sources, RFQ, Superconducting linac, RF Systems, Cryogenics, Mechanical layout.  
Transparencies
 
MOP03 Proposal for Reduction of Transverse Emittance of BNL 200 MeV Linac linac, injection, rfq, proton 36
 
  • J. Alessi, J. Beebe Wang, D. Raparia, W.-T. Weng
    BNL, Upton, Long Island, New York
  BNL plans to upgrade the AGS proton beam from the current 0.14 MW to higher than 1.0 MW and beyond for such a neutrino facility which consists of two major subsystems. First is a 1.2 GeV super-conducting linac (SCL) to replace the booster as injector for the AGS. Second is the performance upgrade for the AGS itself for the higher intensity and repetition rate. For high intensity proton accelerators, such as the upgraded AGS, there are very stringent limitations on uncontrolled beam losses. A direct effect of linac beam emittance is the halo/tail generation in the circulating beam. Studies show the estimated halo/tail generation in the beam for present normalized RMS emittance of linac beam is unacceptable. To reduce the transverse emittance of 200 MeV linac, the existing radio frequency quadrupole linac (RFQ) has to be relocated closer to drift tube linac (DTL) tank 1 to meet emittance requirement for the AGS injection with low loss. This paper will present the various options of matching between RFQ and DTL, and chopping options in the low energy beam transport (LEBT).  
 
MOP05 The HITRAP-Decelerator for Heavy Highly-Charged Ions ion, rfq, extraction, storage-ring 39
 
  • L. Dahl, W. Barth, T. Beier, W. Vinzenz
    GSI, Darmstadt
  • C. A. Kitegi, U. Ratzinger, A. Schempp
    IAP, Frankfurt-am-Main
  The GSI accelerator facility provides highly charged ions up to U92+ by stripping the ions at 400 MeV/u in the transfer line from the SIS18 (Heavy Ion Synchrotron) to the ESR (Experimental Storage Ring). The ESR provides high quality beams by means of stochastic cooling and electron cooling. Deceleration down to 4 MeV/u was already successfully demonstrated. After suitable rebunching, further deceleration down to 6 keV/u, neccessary for the capture of the ions by a penning trap, is done by IH/RFQ-structures. All cavities are operated at 108 MHz. Recently the HITRAP-project (Heavy Ion Trap), described in a Technical Design Report, was approved. The layout of the decelerator and the beam dynamics in different sections are reported.  
 
MOP07 High Current Beam Transport to SIS18 injection, ion, simulation, space-charge 45
 
  • S. Richter, W. Barth, L. Dahl, J. Glatz, L. Groening, S. Yaramishev
    GSI, Darmstadt
  The optimized transversal and longitudinal matching of space charged dominated ion beams to SIS18 is essential for a loss free injection. This paper focuses on the beam dynamics in the transfer line (TK) from the post-stripper accelerator to the SIS18. Transverse beam emittance measurements at different positions along the TK were done. Especially, the different foil stripping modes were investigated. A longitudinal emittance measurement set-up was commissioned at the entry to the TK. It is used extensively to tune all the rebunchers along the UNILAC. An addition, a test bench is in use for measurements of longitudinal bunch profiles, which enables to monitor for the final debunching to SIS18. Multi particle simulations by means of PARMILA allow a detailed analysis of experimental results for different ion currents.  
 
MOP08 Investigation of the Beam Matching to the GSI-Alvarez DTL under Space Charge Conditions ion, quadrupole, space-charge, simulation 48
 
  • S. Yaramishev, W. Barth, L. Dahl, L. Groening, S. Richter
    GSI, Darmstadt
  The UNILAC consists of the 36 MHz high current RFQ/IH-injector, a gas stripper section at an energy of 1.4 MeV/u and a 108 MHz Alvarez poststripper, accelerating all ions up to of 11.4 MeV/u. The design beam current for U28+ is 12.6 emA at full energy. After the stripping process the electrical beam current is increased by a factor of 7 for uranium. This leads to a significant beam emittance growth during the transport through the charge state separator and the matching section to the Alvarez DTL. The paper reports results of beam experiments focused on the matching of the high intensity beams to the Alvarez for different ion species. Measured data are compared with the results of beam dynamics simulations. Possible improvements of the transverse focusing in the Alvarez linac are discussed and the total impact to the beam quality at the synchrotron injection is evaluated.  
Transparencies
 
MOP10 The IH Cavity for HITRAP rfq, ion, bunching, simulation 54
 
  • C. A. Kitegi, U. Ratzinger
    IAP, Frankfurt-am-Main
  • S. Minaev
    ITEP, Moscow
  RFQs are already successfully used to decelerate ions and to match them to ion traps. Within the Heavy Ions TRAP project HITRAP at GSI a combination of an IH drift tube cavity operating at the H11(0) mode and a 4-rod RFQ is proposed to decelerate the 1 ms long heavy ion bunches (up to U92+) from 4 A×MeV to 6 A keV after storage ring extraction. The transition energy from the IH into the RFQ is 0.5AmeV. The operating frequency is 108.408 MHz. The A/q range of the linac is up to 3.A 4-gap quarter wave resonator working at 108.408MHz provides theμbunch structure for the IH. The transmission mainly defined by the buncher is about 30%. An alternative 2nd harmonic bunching section, which allows higher transmission and/or smaller longitudinal emittance, will be discussed.By applying the KONUS dynamics, the 2.7 meter long IH cavity will perform a high efficient deceleration by up 10.5 MV with 200kW rf power. The beam dynamics performed with the LORASR simulation code will be shown. It is aimed to reach an effective shunt impedance around 220MW/m for the IH cavity  
 
MOP11 The Compact 20 MV IH-DTL for the Heidelberg Cancer Therapy Facility simulation, rfq, ion, linac 57
 
  • Y.R. Lu, Y.R. Lu, B. Schlitt
    GSI, Darmstadt
  • S. Minaev
    ITEP, Moscow
  • U. Ratzinger, R. Tiede
    IAP, Frankfurt-am-Main
  A clinical synchrotron facility for cancer therapy using energetic proton and ion beams (C, He and O) is under construction and will be installed at the Radiologische Universitätsklinik in Heidelberg, Germany, starting in 2005. The different rf tuning concepts and tuning results for an 1:2 scaled IH-DTL model cavity are presented. Microwave Studio simulations have been carried out for the model and for the real power cavity. Results from the model measurements and the field simulations agree very well also for the higher order modes. The beam matching from the RFQ to the IH-DTL was optimised. Beam dynamics simulations using the LORASR code and starting with a particle distribution at the RFQ exit as calculated with PARMTEQ are presented. The IH drift tube array was matched with the gap voltage distribution resulting from rf model measurements.  
 
MOP26 ERLP Gun Commissioning Beamline Design electron, diagnostics, gun, laser 93
 
  • D.J. Holder, C.K.M. Gerth, F.E. Hannon
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R.J. Smith
    CLRC, Daresbury, Warrington, Cheshire
  The 4GLS project is a novel next-generation solution for a UK national light source. It is based on an energy recovery linac (ERL) operating at high average beam currents up to 100 mA and with compression schemes producing pulses in the 10 - 100 fs range. This challenging accelerator technology, new to Europe, necessitates a significant R&D programme and a major part of this is a low-energy prototype, the ERLP, which is currently under construction at Daresbury Laboratory, in the north-west of England. The first components of ERLP to be built will be the DC photocathode gun and low-energy beam transport and diagnostics. The gun will initially be operated with a diagnostic beamline in order to measure the properties of the high-brightness beams generated as fully as possible. This will allow comparison of its performance with the results of multi-particle tracking codes, prior to its integration into the ERLP machine. The diagnostic beamline will include diagnostics for measuring the transverse and longitudinal properties of the electron beam. This paper will describe the design of this diagnostic beamline and demonstrate through simulation, the expected characteristics and performance achievable from this system.  
 
MOP28 A Study of Higher-Band Dipole Wakefields in X-Band Accelerating Structures for the G/NLC dipole, linac, simulation, impedance 99
 
  • R.M. Jones
    SLAC/ARDA, Menlo Park, California
  The X-band linacs for the GLC/NLC (Global Linear Collider/Next Linear Collider) have evolved from the DDS (Damped Detuned Structure) series [1,2]. The present series of accelerating structures are each 60 cm in length and incorporate both damping and detuning of the dipole modes which comprise the wakefield. In order to adequately damp the wakefield the dipole frequencies of adjacent structures are interleaved. The properties of the first dipole band have been extensively studied. However, limited analysis has been done on the higher order dipole bands. Here, we calculate the contribution of the higher order bands of the interleaved structures to the wakefield using a mode matching computer code [3]. Beam dynamics issues are also studied by tracking the beam through the complete linac using the particle beam tracking code LIAR [4].

[1] R.M Jones et al,1996,Proc. EPAC96 (also SLAC-PUB-7187) [2] J.W. Wang et al, 2000, Proc. LINAC2000 (also SLAC-PUB-8583) [3] V.A. Dolgashev, Ph.D. thesis, Budker INP, Novosibirsk, 2002.[4] R. Assman et al, LIAR, SLAC-PUB AP-103

 
 
MOP29 RHIC Electron Cooler electron, cathode, gun, linac 102
 
  • J. Kewisch, I. Ben-Zvi, R. Calaga, X.Y. Chang, A. Jain, V. Litvinenko, C. Montag, V. Yakimenko
    BNL, Upton, Long Island, New York
  Electron cooling has been applied in many accelerators with low energies where cooling times are short. Electron cooling is now considered for RHIC, where gold ions are stored at 100 GeV/u. For a cooling time of one hour an electron beam with 55 MeV and 10 nC/bunch is necessary. The transverse normalized emittance must be 50 mm·mrad, the energy spread 10-4. Only a Photo-cathode Energy Recovery LINAC (PERL) promises such quality. For a minimum electron temperature inside the 1 Tesla cooling solenoid it is necessary to have a "magnetized beam", i.e. a beam from a cathode immersed in a longitudinal magnetic field. The emittance compensation scheme used in RF guns was adapted so that the magnetization does not lead to strong emittance growth. A super-conducting cavity was developed for the RHIC electron cooler, optimized for high current operation. Simulations with the TBBU computer code show a multi-bunch beam breakup threshold of 3 Amperes. After acceleration the bunches are lengthened and the energy spread is reduced by rotation in the longitudinal phase space. The original bunch length must be restored by a second rotation before deceleration and energy recovery.  
 
MOP37 Optimization of Positron Capture in NLC positron, target, electron, injection 120
 
  • Y.K. Batygin
    SLAC, Stanford
  In the Next Linear Collider design, the positron capture system includes a positron production target, a flux concentrator, and a linac to accelerate positrons up to 1.9 GeV, the injection energy of the positron pre-damping ring. Two schemes for positron production have been studied:
  1. a conventional approach with a 6.2 GeV electron beam interacting with a high-Z target and
  2. polarized positron production using polarized photons generated in a helical undulator by a 150 GeV electron beam which then interact with a positron production target.
The capture system has been optimized to insure high positron yield into the 6-dimensional acceptance of the pre-damping ring. Various parameters affecting the positron capture have been analyzed, including: positron deceleration after the flux concentrator, transverse and longitudinal electron beam sizes for positron generation, energy compression after acceleration, etc. As a result of these optimization studies, the positron yield in the conventional scheme has been increased from 1.0 to at least 1.5 and for the polarized positron scheme from 0.25 to 0.30 while maintaining 60% positron polarization. 		 
Transparencies
 
MOP40 A Study Of Coupler-Trapped Modes In X-Band Linacs for the GLC/NLC simulation, linear-collider, collider, linac 129
 
  • R.M. Jones, V.A. Dolgashev
    SLAC/ARDA, Menlo Park, California
  • Z. Li
    SLAC, Menlo Park, California
  • J. Wang
    SLAC/ARDB, Menlo Park, California
  Each of the X-band accelerating structures for the GLC/NLC consist of 55 cells which accelerate a train of charged particles. The cells are carefully designed to ensure that the transverse wakefield left behind each bunch does not disrupt the trailing bunches. However, unless attention is paid to the design of the fundamental mode coupler, then a dipole mode is trapped in the region of the coupler and cells. This mode can give rise to severe emittance dilution if care is not taken to avoid a region of resonant growth in the emittance. Here, we present results on HFSS simulations, cold test experimental measurements and beam dynamics simulations arising as a consequence of the mode trapped in the coupler. The region in which the trapped mode has little influence on the beam is delineated.  
 
MOP41 Emittance-Imposed Alignment and Frequency Tolerances for the TESLA Linear Collider linac, collider, dipole, luminosity 132
 
  • N. Baboi
    DESY, Hamburg
  • R.M. Jones
    SLAC/ARDA, Menlo Park, California
  One option in building a future 500 GeV c.m. collider is to use superconducting 1.3 GHz 9-cell cavities. Wakefields excited by the bunch train in the TESLA linac can resonantly drive the beam into unstable operation such that a BBU (Beam Break Up) mode results or at the very least significant emittance dilution occurs. The largest kick factors (proportional to the transverse fields which transversely kick the beam off axis) are found in the first three dipole bands and hence multi-bunch emittance growth is mainly determined from these bands. These higher order dipole modes are damped by carefully orientating higher order mode couplers at the downstream end of the cavities. We investigate the dilution in the emittance of a beam injected with an initial offset from the axis of the cavities. The dependence of beam emittance on systematic errors in the cell frequencies is investigated. We also vary the bunch spacing in order to simulate a systematic frequency error. While scanning the bunch spacing over a wide range, the emittance presents sharp peaks since only few modes contribute effectively to emittance growth. The locations of these peaks sets the frequency tolerances on the structures.  
 
MOP42 Linac Alignment and Frequency Tolerances from the Perspective of Contained Emittances for the G/NLC alignment, simulation, linac, dipole 135
 
  • R.M. Jones
    SLAC/ARDA, Menlo Park, California
  We maintain the stable progress of a beam consisting of a train of bunched charges, by a careful design of the geometry of the structures [1]. In practice, the next generation of linear colliders will consist of several tens of thousands of X-band accelerating structures and this will entail inevitable errors in the dimensions and alignments of cells -and groups thereof. These errors result in a dilution of the beam emittance and consequently a loss in overall luminosity of the collider. For this reason it is important to understand the alignment tolerances and frequency tolerances that are imposed for a specified emittance budget. Here we specify an emittance dilution of no more than 10% of the initial value and we track the progress of the beam down the linac whilst accelerating structures (and sub-groups thereof) are misaligned in a random manner and at the same time random frequency are incorporated with structures. This results in tolerances in both frequency errors and sets of alignment errors to be imposed on the structures for a specified emittance dilution.

[1] R.M. Jones, 1997, SLAC NLC-Note 24.

 
 
MOP45 A Potential Signal for Luminosity Optimisation in CLIC luminosity, linac, photon, simulation 144
 
  • D. Schulte
    CERN, Geneva
  Luminosity optimisation will be challenging in the compact linear collider (CLIC) studied at CERN. In particular, the signals which can be used for luminosity optimisation need to be identified. The strong beam-beam interaction in CLIC will give rise to the emission of a few megawatts of beamstrahlung; this is a potential candidate for such a signal. In this paper luminosity optimisation using the beamstrahlung is attempted for realistically shaped bunches.  
 
MOP47 Limiting Effects in the Round-To-Flat Beam Transformation simulation, quadrupole, chromatic-effects, gun 150
 
  • Y.-E. Sun, K.-J. Kim
    Chicago University, Chicago, Illinois
  • P. Piot
    FNAL, Batavia, Illinois
  The transformation of an angular-momentum-dominated beam into a flat beam was analyzed in Ref. [K.-J. Kim, Phys. rev. ST A&B, vol 6, 104002 (2003)]. The analysis was performed assuming that the beam and the transport channel upstream of the flat beam transformer are cylindrically symmetric and that the particle dynamics is symplectic. We extend the analysis to include chromatic and space-charge effects as well as asymmetries in the four dimensional transverse phase space distribution.  
 
MOP48 Gamma and X-rays Production for Experiments at ELSA Facility electron, laser, target, linac 153
 
  • J. Lemaire
    CEA/DAM, Bruyères-le-Châtel
  The ELSA facility is a high brightness 18 MeV electron source dedicated to electron radiation, gamma-rays and picosecond hard and soft X-rays. It consists of a 144 MHz RF photoinjector producing short bunches which are further accelerated to a final energy varying from 2 to 18 MeV thanks to three 433 MHz RF cavities. Former beam compression design used a half turn magnet compressor system. It has been recently replaced by a double alpha magnet compressor. Electron beams are now delivered to a new experimental room. We present the new panel of interests offered by this facility in term of gamma-ray and X-ray production.  
 
MOP73 Development of a Permanent Magnet ECR Source to Produce a 5 mA Deuteron Beam at CEA/Saclay extraction, plasma, simulation, permanent-magnet 192
 
  • R. Gobin, D.D. De Menezes, O. Delferriere, R. Ferdinand, F. Harrault
    CEA/DAPNIA-SACM, Gif-sur-Yvette Cedex
  • P.-Y. Beauvais, G. Charruau, Y. Gauthier
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • N. Comte
    CEA/Saclay, Gif-sur-Yvette
  • P. Lehérissier, J.Y. Pacquet
    GANIL, Caen
  The high intensity light ion source, SILHI, is an ECR ion source operating at 2.45 GHz which produces high intensity (over 100 mA) proton or deuteron beams at 95 keV. It has been moved in the IPHI building after a complete dismantling. At the beginning of 2003, after tuning the source parameters at standard values, the first extracted beam reached more than 70 mA within a few minutes. This encouraged us to propose a permanent magnet source based on the SILHI design to fit in with the injector of the Spiral2 project, requesting 5 mA of D+ beam with an energy of 40 keV and a normalized rms emittance lower than 0.2 π·mm·mrad. The new source has been recently assembled and the first beam (proton) extracted. After a brief source description, the preliminary results will be reported and discussed.  
 
MOP76 Ultra-High-Vacuum Problem for 200 keV Polarized Electron Gun with NEA-GaAs Photocathode gun, electron, ion, cathode 201
 
  • T. Nakanishi, F. Furuta, M. Kuwahara, K. Naniwa, S. Okumi, M. Yamamoto, N. Yamamoto, K. Yasui
    DOP Nagoya, Nagoya
  • H. Kobayakawa, Y. Takashima
    DOE Nagoya, Nagoya-City
  • M. Kuriki, H. Matsumoto, M. Yoshioka
    KEK, Ibaraki
  For a polarized electron source based on photoemission from GaAs, a NEA (Negative Electron Affinity) surface makes an indispensable role to extract polarized electrons in conduction band into vacuum. The NEA surface is also considered as a best surface to provide a beam with a minimum initial beam-emittance. However, the NEA surface state is realized by a mono-layer of electric dipole moment (that is Ga(-)-Cs(+)) formed at the surface and thus it is easily degraded by
  1. desorption of harmful residual gas,
  2. desorption of harmful gas created by field emission from HV-cathodes and
  3. ion back-bombardment.
In order to reduce the effects of (a) and (c), extremely good UHV is required. Presently total pressure of 4·10-12 torr and respective partial pressures of 3·10-13 torr and 4·10-13 torr for H2O and CO2 were achieved at our gun chamber. Field emission dark current must be extremely suppressed to reduce the effect of (c). The maximum field gradient of 7.8 MV/m is applied for electrode envelope (3.0 MV/m for cathode surface) at 200 kV DC bias-voltage, but total dark current was suppressed below 1 nA for our electrodes. The NEA lifetime under these conditions will be reported at the conference. 		 
 
MOP77 Design Parameters of the Normal Conducting Booster Cavity for the PITZ-2 Test Stand vacuum, coupling, booster, gun 204
 
  • V.V. Paramonov, N.I. Brusova, A.I. Kvasha, A. Menshov, O.D. Pronin, A.K. Skasyrskaya, A.A. Stepanov
    RAS/INR, Moscow
  • A. Donat, M. Krasilnikov, A. Oppelt, F. Stephan
    DESY Zeuthen, Zeuthen
  • K. Flöttmann
    DESY, Hamburg
  The normal conducting booster cavity is intended to increase the electron bunch energy in the Photo Injector Test (DESY, Zeuthen) stage 2 experiments. The normal conducting cavity is selected due to infrastructure particularities. The L-band cavity is designed to provide the accelerating gradient up to 14 MV/m with the total input RF power 8.6 MW, RF pulse length up to 900 mks and repetition rate 5 Hz. The multi-cell cavity is based on the CDS compensated accelerating structure with the improved coupling coefficient value. The main design ideas and decisions are described briefly together with cavity parameters - RF properties, cooling and pumping circuits.  
 
MOP80 Development of Adaptive Feedback Control System of Both Spatial and Temporal Beam Shaping for UV-Laser Light Source for RF Gun laser, electron, gun, cathode 207
 
  • H. Tomizawa, T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, A. Mizuno, S. Suzuki, T.  Taniuchi, K. Yanagida
    JASRI-SPring-8, Hyogo
  • F. Matsui
    FKLAB, Fukui City
  The ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. We have been developing highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. The gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. The electron beam was accelerated up to 4.1 MeV at the maximum electric field on the cathode surface of 175 MV/m. For emittance compensation, two solenoid coils were used. As the first test run, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2 π·mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We applied the both adaptive optics to automatically shape the both spatial and temporal UV-laser profiles with a feedback routine at the same time. We report herein the principle and developing process of our laser beam quality control system.  
 
MOP82 SRF Cavity and Materials R&D at Fermilab superconductivity, superconducting-RF, vacuum, electron 213
 
  • N. Khabiboulline, P. Bauer, L. Bellantoni, T. Berenc, C. Boffo, R. Carcagno, C. Chapman, H. Edwards, L. Elementi, M. Foley, E. Hahn, D. Hicks, D. Mitchell, A. Rowe, N. Solyak, I. Terechkine
    FNAL, Batavia, Illinois
  • A. Gurevich, M. Jewell, D. C. Larbalestier, P. Lee, A. Polyanskii, A. Squitieri
    UW-Madison/ASC, Madison, Wisconsin
  Two 3.9 GHz superconducting RF cavities are under development at FNAL for use in the upgraded Photoinjector Facility. A TM110 mode cavity will provide streak capability for bunch slice diagnostics, and a TM010 mode cavity will provide linearization of the accelerating gradient before compression for better emittance. The status of these two efforts and a review of the FNAL infrastructure development will be given.  
 
TU202 Low Emittance 500 kV Thermionic Electron Gun cathode, gun, electron, space-charge 261
 
  • K. Togawa, H. Baba, T. Inagaki, K. Onoe, T. Shintake, T. Tanaka
    RIKEN Spring-8 Harima, Hyogo
  • H. Matsumoto
    KEK, Ibaraki
  A 500 kV pulsed electron gun has been constructed for the injector system of the SASE-FEL project at SPring-8 (SCSS project). A CeB6 single crystal was chosen as a thermionic cathode, because of its excellent emission properties. We have succeeded in generating a 500 keV beam with 1 A peak current and 3 μs FWHM. The beam was very stable with low jitter. The beam emittance has been measured by means of double-slits method, and the normalized rms emittance of 1.1 π·mm·mrad has been obtained. We report on the experimental result on the emittance measurement of the CeB6 electron gun.  
Transparencies
 
TU203 High Pressure, High Gradient RF Cavities for Muon Beam Cooling radiation, simulation, collider, vacuum 266
 
  • R. P. Johnson, M. Popovic
    FNAL, Batavia, Illinois
  • M.M. Alsharo'a, R.E. Hartline, M. Kuchnir, T.J. Roberts
    Muons, Inc., Batavia
  • C. M. Ankenbrandt, A. Moretti
    Fermilab, Batavia, Illinois
  • K. Beard, A. Bogacz, Y.S. Derbenev
    Jefferson Lab, Newport News, Virginia
  • D. M. Kaplan, K. Yonehara
    IIT, Chicago, Illinois
  High intensity, low emittance muon beams are needed for new applications such as muon colliders and neutrino factories based on muon storage rings. Ionization cooling, where muon energy is lost in a low-Z absorber and only the longitudinal component is regenerated using RF cavities, is presently the only known cooling technique that is fast enough to be effective in the short muon lifetime. RF cavities filled with high-pressure hydrogen gas bring two advantages to the ionization technique:
  1. the energy absorption and energy regeneration happen simultaneously rather than sequentially, and
  2. higher RF gradients and better cavity breakdown behavior are possible than in vacuum due to the Paschen effect.
These advantages and some disadvantages and risks will be discussed along with a description of the present and desired RF R&D efforts needed to make accelerators and colliders based on muon beams less futuristic. 		 
Transparencies
 
TU302 Future Developments in Electron Linac Diagnostics linac, instrumentation, laser, electron 280
 
  • M.C. Ross
    SLAC/NLC, Menlo Park, California
  The next generation of electron linacs will fill two different roles:
  1. ultra-low emittance, very high power accelerators for linear colliders and
  2. ultra-short bunch, high stability accelerators for SASE X-ray production.
In either case, precision control based on non-invasive, reliable, beam instrumentation will be required. For the linear collider, low emittance transport is an important concern for both warm and superconducting linacs. Instrumentation will be used to control and diagnostics will be used to validate emittance preserving strategies, such as beam based alignment and dispersion - free steering. Tests at the KEK ATF and the SLAC FFTB have demonstrated the required performance for beam position and beam size monitors. Linacs intended for FEL's will require precision bunch length diagnostics because of expected non-linear micro-bunching processes. A wide variety of devices are now in development at FEL prototypes, including TTF2 at DESY and SPPS at SLAC. We present a review of the new diagnostic systems. 		 
Transparencies
 
TUP01 RFQ Drift-Tube Proton Linacs in IHEP focusing, rfq, linac, quadrupole 285
 
  • Yu. Budanov, O.K. Belyaev, S.V. Ivanov, A.P. Maltsev, I.G. Maltsev, V.B. Stepanov, S.A. Strekalovskyh, V.A. Teplyakov, V. Zenin
    IHEP Protvino, Protvino, Moscow Region
  A linac with drift tubes and RF quadrupoles (alias, an RFQ DTL) constitutes a natural extension of the RFQ concept towards higher beam energies. Complementing an RFQ with drift tubes intermitted by spacer electrodes separates functions of focusing and acceleration. Such a structure allows for an increased accelerating rate and upgrades shunt impedance to values competitive against those inherent in the other common accelerator types. Various accelerating/focusing structures for the RFQ DTLs were implemented in IHEP. Their succession is marked by a progress in performance, which is due to efforts in design, manufacturing technology and calculation technique advances that facilitated R&D of such the structures. A sound practical expertise in the field is accumulated. The 30 MeV RFQ DTL is in service as an injector for a 1.5 GeV PS of IHEP since 1985. An upgraded successor – the RFQ DTL, employing a cavity loaded by a novel accelerating/focusing structure with an increased accelerating rate, is now being assembled and tested. Its pre-commissioning results will be outlined. Prospects in R&D of a structure suitable for a front-end part of the CERN SPL will be evaluated.  
Transparencies
 
TUP05 Beam Dynamics for a new 160 MeV H- Linac at CERN (LINAC4) linac, rfq, quadrupole, simulation 297
 
  • F. Gerigk
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • E. Benedico Mora, A.M. Lombardi, E.Zh. Sargsyan, M. Vretenar
    CERN, Geneva
  LINAC4 is a normal conducting H- linac proposed at CERN to provide a higher proton flux to the CERN accelerator chain. It should replace the existing LINAC2 as injector for the PS booster. The same machine can also operate in the future as the front end of the SPL, a 2.2 GeV superconducting linac with 1.8 mA average current. At present the test set-up for LINAC4 consists of a Radio Frequency Quadrupole (RFQ), a chopper line, a Drift Tube Linac (DTL), and Cell Coupled DTL (CCDTL) operating at 352.2 MHz and finally a Side Coupled Linac (SCL) at 702.2 MHz. This paper discusses the overall beam dynamics concept, presents the optics for the different sections of the machine and compares end-to-end simulations realised with two tracking codes (PATH and IMPACT). Estimates of beam loss due to various error sources are presented and the challenging features in the current design are highlighted.  
Transparencies
 
TUP15 Space Charge Compensation in Low Energy Proton Beams electron, space-charge, proton, ion 324
 
  • A.B. Ismail, U.D. Uriot
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • R. Duperrier
    CEA/DAPNIA-SACM, Gif-sur-Yvette Cedex
  • N. Pichoff
    CEA/DAM, Bruyères-le-Châtel
  High power 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. In this low energy part, the space charge self force, induced by a high intensity beam, has to be carefully managed. This nonlinear force can generate a high irreversible emittance growth of the beam. To reduce space charge effects, neutralization of the beam charge can be done by capturing some particles of the ionised residual gas in the vacuum chamber. This space charge compensation (SCC) regime complicates the dynamic study. Modelling the beam behaviour in such regime would be a significant contribution to the development of high intensity accelerators. Numerical and experimental study of SCC is in progress on the Saclay High Intensity Proton Injector. Experimental measurements and 2D/3D simulations of proton beam SCC will be presented.  
 
TUP16 Investigation on Beam Dynamics Design of High-Intensity RFQs rfq, focusing, space-charge, acceleration 327
 
  • C. Zhang, A. Schempp
    IAP, Frankfurt-am-Main
  • J. Chen, J. Fang, Z.Y. Guo
    PKU/IHIP, Beijing
  Recently various potential uses of high-intensity beams bring new opportunities as well as challenges to RFQ accelerator research because of the new problems arising from the strong space-charge effects. Unconventional concepts of beam dynamics design, which surround the choice of basic parameters and the optimization of main dynamics parameters’ variation along the machine, are illustrated by the designing Peking University (PKU) Deuteron RFQ. An efficient tool of LANL RFQ Design Codes for beam dynamics simulation and analysis, RFQBAT, is introduced. Some quality criterions are also presented for evaluating design results.  
 
TUP18 Beam Dynamics Issues of SPES-1 Linac linac, quadrupole, simulation, rfq 330
 
  • E. Fagotti
    INFN Milano, Milano
  • M. Comunian, A. Palmieri, A. Pisent
    INFN/LNL, Legnaro, Padova
  An Independent Superconducting Cavity Linac able to accelerate 10 mA CW proton beam up to 20 MeV has been studied for the SPES-1 project. This paper presents the results of beam dynamics studies through SPES linac including mapped fields effects on cavities and magnets.  
 
TUP19 Characterization of Beam Parameter and Halo for a High Intensity RFQ Output under Different Current Regimes rfq, simulation, space-charge, proton 333
 
  • E. Fagotti
    INFN Milano, Milano
  • M. Comunian, A. Palmieri, A. Pisent
    INFN/LNL, Legnaro, Padova
  The characterization of the beam distribution at the exit of a high intensity RFQ is a crucial point in view of a correct simulation of beam behavior in the following linac structure. At this scope we need to know the beam halo quantification as a function of the input beam and RFQ parameters. In this paper, the description of Beam halo based upon moments of the particle distribution at the exit of the TRASCO-RFQ is given.  
 
TUP22 A Simulation Study on Chopper Transient Effects in J-PARC Linac beam-losses, linac, simulation, injection 342
 
  • M. Ikegami
    KEK, Ibaraki
  • Y. Kondo, T. Ohkawa, A. Ueno
    JAERI, Ibaraki-ken
  J-PARC linac has an RF chopper system to reduce uncontrolled beam loss in the succeeding ring injection. The chopper system is located in MEBT (Medium Energy Beam Transport line) between a 3 MeV RFQ and a 50 MeV DTL, and consists of two RFD (Radio-Frequency Deflection) cavities and a beam collector. During the rising- and falling-times of the RFD cavities, the beams are half-kicked and cause excess beam loss downstream. In this paper, the behavior of these half-kicked beams is examined with 3D PARMILA simulations, and resulting beam loss is estimated.  
Transparencies
 
TUP23 A Simulation Study on Error Effects in J-PARC Linac linac, injection, simulation, beam-losses 345
 
  • M. Ikegami
    KEK, Ibaraki
  • Y. Kondo, T. Ohkawa, A. Ueno
    JAERI, Ibaraki-ken
  In high-current proton linacs, prevention of excess beam loss is essentially important to enable hands-on maintenance. In addition, requirements on the momentum spread and transverse emittance are quite severe for J-PARC linac to realize effective injection to the succeeding RCS (Rapid Cycling Synchrotron). As losses and beam-quality deterioration are believed to be mainly caused by various errors, such as misalignment, RF mistuning, etc, it is essentially important to perform particle simulations for J-PARC linac with as realistic errors as possible to estimate their effects. In this paper, effects of realistic errors on beam loss and beam-quality deterioration in J-PARC linac are examined with a systematic 3D simulations with PARMILA. Necessity of transverse collimation is also discussed.  
 
TUP26 Alternating Phase Focusing in Low-Velocity Heavy-Ion Superconducting Linac focusing, linac, ion, heavy-ion 348
 
  • P.N. Ostroumov, K.W. Shepard
    ANL/Phys, Argonne, Illinois
  • A. Kolomiets
    ITEP, Moscow
  • E.S. Masunov
    MEPhI, Moscow
  The low-charge-state injector linac of the RIA post-accelerator is based on ~60 independently phased SC resonators providing total ~70 MV accelerating potential. The low charge-state beams, however, require stronger transverse focusing, particularly at low velocities, than is used in existing SC ion linacs. For the charge-to-mass ratios considered here (q/A = 1/66) the proper focusing can be reached by the help of strong SC solenoid lenses with the field up to 15 T. Magnetic field of the solenoids can be reduced to 9 T applying an Alternating Phase Focusing (APF). A method to set the rf field phases has been developed and studied both analytically and by the help of the three-dimensional ray tracing code. The paper discusses the results of these studies.  
 
TUP29 Proton Beam Dynamics of the SARAF Linac simulation, linac, proton, beam-losses 354
 
  • A. Shor, D. Berkovits, G. Feinberg, S. Halfon
    SOREQ, Yavne
  • K. Dunkel
    ACCEL, Bergisch Gladbach
  We have performed proton beam dynamics simulation for the SARAF, 40 MeV and 4 mA, linac. The calculation is using the GPT code and includes effects of space charge. It demonstrates that for an initial 6D Waterbag distribution beam, a tune can be obtained with longitudinal rms emittance growth of about 10 % and transverse normalized rms emittance growth of 20%, and a transverse beam envelope of 5000 macro-particle well within the linac beam pipe. Beam loss is estimated by fitting a radial Gaussian to the particle distribution along the linac. A 1 nA beam envelope is obtained by extrapolating the tail of the radial-Gaussian function. The 1nA beam envelope is still well within the beam bore radius. Benchmark simulation with a 6D Gaussian initial distribution, with the same rms quantities, exhibits a more extended tail that may result in a higher beam loss. This point will receive a further study.  
Transparencies
 
TUP41 Multi-Bunch Beam Dynamics Studies for the European XFEL linac, simulation, electron, collider 357
 
  • N. Baboi
    DESY, Hamburg
  In the X-ray free electron laser planned to be built at DESY (TESLA XFEL) the acceleration of the electron bunches will be made with 9-cell superconducting cavities. These cavities have been initially developed within the TESLA linear collider study. The impact of the higher order modes (HOM) has been shown to be within the acceptable beam dynamics limits for the collider. For the XFEL the dynamics is relaxed from point of view of multi-bunch effects (e.g. shorter length, higher emittance). However the lower energy and different time structure of the beam make the study of the HOM effects in the XFEL linac necessary. Multi-bunch beam dynamics studies are ongoing. The results of the HOM measurements at the TESLA Test Facility are used. Several options for the beam structure, as necessary for various applications, are studied. The results will be discussed.  
Transparencies
 
TUP43 The Superconducting CW Driver Linac for the BESSY-FEL User Facility linac, simulation, gun, beam-loading 363
 
  • J. Knobloch
    BESSY GmbH, Berlin
  A CW FEL User Facility for the VUV to soft X-ray spectral range based on a cascaded HGHG-FEL scheme is planned at the BESSY site. The Technical Design Report has recently been submitted to the German Wissenschaftsrat. Beam acceleration to 2.3 GeV is provided by a 144-cavity superconducting driver linac based on TESLA technology modified for CW operation. Initially, a high-rep-rate normal-conducting photoinjector will be used but a fully CW superconducting version is being investigated for a future upgrade. Bunch compression to 2 kA peak current is achieved in a three-stage scheme involving two bunch compressors and an arc. An overview of the linac layout, including the rf and cryogenic distribution, is provided here. We also discuss the impact of CW operation and the modifications to the TESLA technology that are necessary. Predictions of the linac performance are also given.  
Transparencies
 
TUP45 Extended Parametric Evaluation for 1 Å FEL - Emittance and Current Requirements undulator, electron, radiation, gun 369
 
  • M. Pedrozzi, G. Ingold
    PSI, Villigen
  In the synchrotron radiation community there is a strong request for high brightness, coherent X-ray light pulses, especially in the 1 to 0.1 nm wave length range. A Free Electron Laser (FEL), driven by a linear single pass accelerator, is today the most promising mechanism able to produce such radiation. Since the electron beam brightness plays a major role in the laser saturation process and in the final energy of the driving linac, many laboratories are presently working on a new generation of low emittances sources. The present analysis will give an indication about the FEL behaviour and the undulator parameters versus the slice beam quality (emittance, current, energy spread).  
 
TUP47 The Photo Injector Test Facility at DESY Zeuthen: Results of the First Phase laser, gun, cathode, electron 375
 
  • A. Oppelt, K. Abrahamyan, I. Bohnet, J. Bähr, U. Gensch, H.-J. Grabosch, J.H. Han, M. Krasilnikov, D. Lipka, V. Miltchev, B. Petrosyan, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • W. Ackermann, W.F.O. Müller, S. Setzer, T. Weiland
    TU Darmstadt, Darmstadt
  • J.-P. Carneiro, K. Flöttmann, S. Schreiber
    DESY, Hamburg
  • E. Jaeschke, D. Krämer, D. Richter, M. von Hartrott
    BESSY GmbH, Berlin
  • P. Michelato, C. Pagani, D. Sertore
    INFN/LASA, Segrate (MI)
  • J. Rossbach
    Uni HH, Hamburg
  • W. Sandner, I. Will
    MBI, Berlin
  • I. Tsakov
    INRNE, Sofia
  The photo injector test facility at DESY Zeuthen successfully concluded it's first phase of operation in November 2003 (PITZ1). After a complete characterization of the injector, the gun has been delivered to Hamburg and has already been taken into operation on the VUV-FEL. The measurement program for the year 2003 included RF commissioning, emittance studies, momentum and bunch length measurements, and studies of the influence of the drive laser parameters. We provide an overview on the latest achievements in all of these topics.  
Transparencies
 
TUP48 Progress Report on the Flat Beam Experiment at the Fermilab/Nicadd Photoinjector Laboratory laser, simulation, cathode, quadrupole 378
 
  • Y.-E. Sun, K.-J. Kim
    Chicago University, Chicago, Illinois
  • N. Barov
    Northern Illinois University, DeKalb, Illinois
  • K. Desler
    DESY, Hamburg
  • H. Edwards, P. Piot, J. Santucci, J. Wennerberg
    FNAL, Batavia, Illinois
  • M. Huening
    Fermilab, Batavia, Illinois
  • S. Lidia
    LBNL/AFR, Berkeley, California
  • R. Tikhoplav
    Rochester University, Rochester, New York
  We report on our present progress toward the investigation on the generation of flat beam from an incoming angular-momentum-dominated beam, along with the associated diagnostics development. We focus on the evolution of the four-dimensional beam matrix upstream and downstream of the round-to-flat beam transformer. Finally we compare our latest experimental results with numerical and analytical models.  
 
TUP53 Temporal Profile of the LCLS Photocathode Ultraviolet Drive Laser Tolerated by the Microbunching Instability undulator, simulation, laser, damping 390
 
  • J. Wu, Z. Huang
    SLAC, Menlo Park, California
  • M. Borland
    ANL, Argonne, Illinois
  • P. Emma
    SLAC/ARDA, Menlo Park, California
  • C. Limborg
    SLAC/SSRL, Menlo Park, California
  The high quality LCLS electron beam generated in the photoinjector is subject to all possible instabilities in the downstream acceleration and compression. The instability can be initiated by any possible density modulation of the electron beam when it is generated at the photocathode. In this note, we prescribe the tolerance on the initial electron beam density modulation possibly introduced by the ultraviolet (uv) laser at the cathode. Our study shows that the initial rms density modulation of the electron beam at the photocathode shall be less than 5 % to ensure the FEL lasing and saturation.  
 
TUP58 Alternative Linac Layout for European XFEL Project linac, space-charge, gun, simulation 399
 
  • Y. Kim, K. Flöttmann, T. Limberg
    DESY, Hamburg
  • Y. Kim, D. Son
    CHEP Korea, Daegu
  To satisfy required beam parameters and to increase the jitter tolerance, we have designed an alternative linac layout with two bunch compressor stages for the European XFEL project. In this paper, we describe start-to-end (S2E) simulation of the alternative linac layout for the European XFEL project, and compare its results with our current linac layout with one bunch compressor stage.  
 
TUP63 The First Results of Bunch Shape Measurements in SNS Linac electron, target, linac, background 408
 
  • A. Feschenko, A. Gaidash, Yu. Kisselev, L.V. Kravchuk, A. Liyu, A. Menshov, A.N. Mirzojan
    RAS/INR, Moscow
  • S. Assadi, W. Blokland, S. Henderson, E.P. Tanke
    ORNL/SNS, Oak Ridge, Tennessee
  • D.-O. Jeon
    ORNL, Oak Ridge
  Three Bunch Shape Monitors with transverse scanning of low energy secondary electrons for the SNS Linac have been developed and fabricated. The peculiarity of the detectors is using of energy separation of the electrons. The separation enables to minimize influence of detached electrons originated from dissociation of H-minus ions in the detector wire target. The first detector was used at the exit of the first DTL tank during its commissioning. The results of Bunch Shape measurements are presented and discussed. These results were used to verify beam quality, to set parameters of the accelerating field, to estimate a longitudinal beam halo and to restore a longitudinal beam emittance.  
Transparencies
 
TUP66 An Alternate Scheme for J-PARC SDTL Tuning simulation, injection, linac, rfq 417
 
  • M. Ikegami
    KEK, Ibaraki
  • Y. Kondo, A. Ueno
    JAERI, Ibaraki-ken
  J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac. As presented in a separate paper, we plan to perform phase-scan with precise TOF (Time Of Flight) beam-energy measurement in RF tuning of SDTL tanks. As a back-up method, we are considering to prepare an RF tuning scheme with rough TOF measurement for SDTL. In this paper, the principle of this scheme is presented, and its advantages and disadvantages are discussed based on a systematic particle simulation.  
 
TUP82 Low Energy Beam Transport using Space Charge Lenses space-charge, rfq, ion, focusing 465
 
  • O. Meusel, A. Bechtold, H. Klein, J. Pozimski, U. Ratzinger, A. Schempp
    IAP, Frankfurt-am-Main
  Gabor lenses provide strong cylinder symmetric electric focusing using a confined nonneutral plasma. The density distribution of the enclosed space charge is defined by the enclosure conditions in transverse and longitudinal direction. For a homogeneous charge density distribution the resulting electrostatic field and therefrom the focusing forces inside the space charge cloud are linear. Additionally in case of a positive ion beam the space charge of the confined electrons causes compensation of the ion beam space charge forces. To study the capabilities of a Gabor double lens system to match an ion beam into a RFQ a testinjector was installed at the IAP and put into operation successfully. First beam profiles and emittance measurements as well as measurements of the beam energy and energy spread have already been performed and show satisfactory results and no significant deviation from the theoretical predictions. To verify the beam focusing of bunched beams using this lens type at beam energies up to 500 keV a new high field Gabor lens was build and will be installed behind of the RFQ.  
 
WE104 State of the Art Electron Bunch Compression electron, radiation, synchrotron, bunching 528
 
  • P. Piot
    FNAL, Batavia, Illinois
  Many accelerator applications such as advanced accelerator R&D, free-electron laser drivers and linear colliders, require high peak current electron bunches. The bunch is generally shortened via magnetic compression. In the present paper we review various bunch compression schemes and discuss their limitations. We present experimental results, achieved at various facilities, along with on-going theoretical work on promising novel compression techniques.  
Transparencies
 
WE201 Results from the Initial Operations of the SNS Front End and Drift Tube Linac linac, rfq, ion-source, ion 533
 
  • V. Aleksandrov
    ORNL/SNS, Oak Ridge, Tennessee
  The Spallation Neutron Source accelerator systems will deliver a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector (the Front-End), capable of producing one millisecond long pulses with 38 mA of peak current at a repetition rate of 60 Hz, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. A 2.5 MeV beam from the injector is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in a Superconducting Linac. The staged beam commissioning of the accelerator is proceeding in parallel with component installation. The Front End and Drift Tube Linac tanks 1-3 have been commissioned at ORNL. The primary design goals of peak current, transverse emittance and beam energy have been achieved. Beam with 38 mA peak current, 1 msec beam pulse length, and 1 mA average beam current has been accelerated through the DTL tank 1. Results and status of the beam commissioning program will be presented.

* on behalf of the SNS Project

 
Transparencies
 
WE204 PAL Linac Upgrade for a 1-3 Å XFEL linac, undulator, radiation, electron 544
 
  • J-O. Oh, W. Namkung
    POSTECH, Pohang
  • Y. Kim
    DESY, Hamburg
  With the successful SASE FEL saturation at 80 nm wavelength at TTF1, TTF2 will begin re-commissioning in the fall of 2004 as an FEL user facility to 6 nm with 1 GeV beams. The high gain harmonic generation is also confirmed by the DUV-FEL experiments at 266 nm with seeding wavelength at 800 nm. In order to realize a hard X-ray SASE FEL (SASE XFEL) with a lower energy beams, we need a long in-vacuum mini-gap undulator and a GeV-scale FEL driving linac that can supply an extremely low slice emittance, a high peak current, and an extremely low slice energy spread. PAL is operating a 2.5 GeV electron linac as a full-energy injector to the PLS storage ring. By adding an RF photo-cathode gun, two bunch compressors, and a 0.5 GeV S-band injector linac to the existing PLS linac, and by installing a 60 m long in-vacuum undulator, the PLS linac can be converted to a SASE XFEL facility (PAL XFEL) which supplies coherent X-ray down to 0.3 nm wavelength. The third harmonic enhancement technique can supply coherent hard X-ray beams to 0.1 nm. The technical parameters related to these goals are examined, and preliminary design details are reviewed for the PAL linac upgrade idea for a 1-3 Å PAL XFEL.  
Transparencies
 
TH101 Status of the J-PARC Linac, Initial Results and Upgrade Plan linac, rfq, ion, proton 554
 
  • Y. Yamazaki
    JAERI/LINAC, Ibaraki-ken
  The J-PARC linac building will be completed by March, 2005, when the installation of the linac components will start. On the other hand, the front end linac, comprising the 3 MeV RFQ linac, the MEBT with the beam chopper, and the 20 MeV DTL first tank, is under beam commissioning in the KEK site. A peak current of 30 mA, which is enough for the 0.6 MW operation of Rapid-Cycling Synchrotron (RCS), was accelerated up to 20 MeV on the second day of the beam commissioning, last November. The detailed study of the system is under way, including the stability test of many components. The front end linac will be shipped to the JAERI Tokai site after the building completion there. The beam commissioning of the 181 MeV linac will start in September 2006, that of the 3 GeV RCS in May, 2007, and that of the 50 GeV Main Synchrotron (MR) in November 2007. The beam acceleration in the MR will be done by March, 2008. It is strongly recommended by the government committee that the upgrade to the 400 MeV linac should start immediately after the completion of the above accelerator system, that is, in April 2008, with the period of three years, aiming the 1 MeV RCS beam power.  
Transparencies
 
TH204 End-to-End Beam Dynamics Simulations for the ANL-RIA Driver Linac linac, simulation, ion, beam-losses 584
 
  • P.N. Ostroumov
    ANL/Phys, Argonne, Illinois
  The proposed Rare Isotope Accelerator (RIA) Facility consists of a superconducting (SC) 1.4 GV driver linac capable of producing 400 kW beams of any ion from hydrogen to uranium. The driver is configured as an array of ~350 SC cavities, each with independently controllable rf phase. For the end-to-end beam dynamics design and simulation we use a dedicated code, TRACK. The code integrates ion motion through the three-dimensional fields of all elements of the driver linac beginning from the exit of the electron cyclotron resonance (ECR) ion source to the production targets. TRACK has been parallelized and is able to track large number of particles in randomly seeded accelerators with misalignments and a comprehensive set of errors. The simulation starts with multi-component dc ion beams extracted from the ECR. Beam losses are obtained by tracking up to million particles in hundreds of randomly seeded accelerators. To control beam losses a set of collimators is applied in designated areas. The end-to-end simulations with the TRACK code have been extremely useful for studies of different options of the driver linac design with respect to beam quality, beam losses and sensitivity of beam parameters to various types of errors.  
Transparencies
 
TH302 End-to-End Beam Simulations for the MSU RIA Driver Linac linac, simulation, ion, alignment 594
 
  • X. Wu, M. Doleans, D. Gorelov, T.L. Grimm, F. Marti, R.C. York, Q. Zhao
    NSCL, East Lansing, Michigan
  The Rare Isotope Accelerator (RIA) driver linac proposed by Michigan State University (MSU) will use a 10th sub-harmonic based, superconducting, cw linac to accelerate light and heavy ions to final energies of ≤400 MeV/u with beam powers of 100 to 400 kW. The driver linac uses superconducting quarter-wave, half-wave, and six-cell elliptical cavities with frequencies ranging from 80.5 MHz to 805 MHz for acceleration, and superconducting solenoids and room temperature quadrupoles for transverse focusing. For the heavier ions, two stages of charge-stripping and multiple-charge-state acceleration will be used to meet the beam power requirements and to minimize the requisite accelerating voltage. End-to-end, three-dimensional (3D), beam dynamics simulations from the ECR to the radioactive beam production targets have been performed. These studies include a 3D analysis of multi-charge-state beam acceleration, evaluation of transverse misalignment and rf errors on the machine performance, modeling of the charge-stripping and stripping-chicane performance, and beam switchyard design. The results of these beam dynamics studies will be presented, and further planned beam dynamics studies will be discussed.  
Transparencies
 
THP03 DESIGN IMPROVEMENT OF THE RIA 80.5 MHZ RFQ rfq, ion, linac, simulation 599
 
  • Q. Zhao, V. Andreev, M. Doleans, D. Gorelov, T.L. Grimm, W. Hartung, F. Marti, S.O. Schriber, X. Wu, R.C. York
    NSCL, East Lansing, Michigan
  An 80.5 MHz, continuous-wave, normal-conducting, radio-frequency quadrupole (RFQ) was designed for the front end of the Rare Isotope Accelerator (RIA) driver linac. It will accelerate various ion beams (hydrogen up to uranium) from 12 keV/u to about 300 keV/u. The 4-meter-long RFQ accepts the pre-bunched beam from the low energy beam transport (LEBT) and captures more than 80% with a current of ~0.3 mA. Beam dynamics simulations show that the longitudinal output emittance is small for both single- and two-charge-state ion beams with an external multi-harmonic buncher. A 4-vane resonator with magnetic coupling windows was employed in the cavity design to provide large mode separation, high shunt impedance, and a small transverse dimension. The results of beam dynamics as well as the electromagnetic simulations are presented.  
 
THP08 The Frankfurt Funneling Experiment rfq, ion, linac, simulation 614
 
  • A. Schempp, U. Bartz, N. Müller, J. Thibus, H. Zimmermann
    IAP, Frankfurt-am-Main
  Funneling is a procedure to multiply beam currents of rf-accelerators at low energies. In the ideal case the beam current can be multiplied in several stages without emittance growth. The Frankfurt Funneling Experiment consists of two ion sources, a Two-Beam RFQ accelerator, two different funneling deflectors and a beam diagnostic equipment system. The whole set-up is scaled for He+ instead of Bi+ for the first funneling stage of a HIIF driver. The progress of our experiment and the results of the simulations will be presented.  
 
THP11 Design of A 352 MHz-Proton-RFQ for GSI rfq, proton, antiproton, linac 620
 
  • A. Schempp, L. Brendel, B. Hofmann
    IAP, Frankfurt-am-Main
  Part of the future project of GSI is a new p-linac for the production of Antiprotons. The 4- Rod-RFQ operating at 350 MHz has to accelerate up to 100 mA protons from an ECR source. Design studies have been made using the Parmteq- and Microwave Studio codes to optimize beam dynamics properties and the field distribution of the RFQ. Results of the design studies will be presented.  
 
THP13 Construction of a 161 MHz, β=0.16 Superconducting Quarter Wave Resonator with Steering Correction for RIA light-ion, linac, vacuum, ion 626
 
  • A. Facco
    INFN/LNL, Legnaro, Padova
  • C. Compton, T.L. Grimm, W. Hartung, F. Marti, R.C. York
    NSCL, East Lansing, Michigan
  • V. Zvyagintsev
    TRIUMF, Vancouver
  We have built a 161 MHz, β=0.16 superconducting Quarter Wave Resonator with steering correction for the low beta section of RIA. This bulk niobium, double wall cavity, compatible with both separate vacuum between beam line and cryostats or unified one, was designed in collaboration between MSU-NSCL and LNL. The design is suitable for extension to other frequencies, e.g. to obtain the 80 MHz, β=0.085 cavity required in RIA. The shaped drift tube allows correction of the residual QWR steering that can cause emittance growth especially in light ions; this could make this resonator a good alternative to Half-Wave resonators in high intensity proton-deuteron linacs, like the SPES injector project at LNL. First test results will be presented.  
 
THP14 High Beta Cavity Optimization for ISAC-II linac, ion, quadrupole, acceleration 627
 
  • R.E. Laxdal, V. Zvyagintsev
    TRIUMF, Vancouver
  • Z.H. Peng
    CIAE, Beijing
  The linac for ISAC-II comprises twenty cavities of medium beta (β=5.8 and 7.1%) quarter wave cavities now in the installation phase. A second stage will see the installation of ~20 MV of high beta quarter wave cavities (~10.4%). The cavity structure choice depends on the efficiency of operation, cost, stability, beam dynamics and schedule. Two main cavity types are considered; a low frequency 106 MHz option and a high frequency 141 MHz cavity. We compare and contrast the cavity choices.  
 
THP26 Comparison of 2 Cathode Geometries for High Current (2 kA) Diodes cathode, simulation, electron, focusing 654
 
  • N. Pichoff
    CEA/DAM, Bruyères-le-Châtel
  • F. Bombardier, M. Caron, E. Merle, C. Noël, O. Pierret, R. Rosol, C. Vermare
    CEA, Pontfaverger-Moronvilliers
  • D.C. Moir
    LANL, Los Alamos, New Mexico
  • A. Piquemal
    CEA/PTN, Bruyères-le-Châtel
  AIRIX (FRANCE) and DARHT axis-1 (USA) are two high current accelerators designed for flash X-ray radiography. The electron beam produced (2 kA, 3.5 to 3.8 MV, 60 ns) is extracted from a velvet cold cathode. Specific calculations have demonstrated the influence of the cathode geometry on the emitted beam profile [1]. To check this assumption we have made two different experiments (DARHT March 2003 – AIRIX March 2004). We have compared the beam characteristics with two different geometries both theoretically and experimentally. The beam simulations have been done with 3 codes: a home-made code (M2V) and 2 commercial codes (PBGUNS and MAGIC). The extracted beam current and transverse profiles, for the first experiment, have been measured and compared to simulations results. In the second one, we have compared the beam’s extracted current and the energy spread.

[1] E. Merle et al., "Efforts to Improve Intense Linear Induction Accelerator (LIA) Sources for Flash Radiography",Proceedings of the LINAC2002 conference. August 19-23, 2002 Gyeongju, Korea.

 
 
THP27 Ultra Low Emittance Electron Gun Project for FEL Application gun, cathode, electron, simulation 657
 
  • R. Ganter, M. Dehler, J. Gobrecht, C. Gough, G. Ingold, S. Leemann, M. Paraliev, M. Pedrozzi, J.-Y. Raguin, L. Rivkin, V. Schlott, A. Streun, A. Wrulich
    PSI, Villigen
  • A. Candel, K. Li
    ETH, Zürich
  Most of the current 1Å Free-Electron Laser (FEL) projects are based on thermionic or photocathode guns aiming at an electron beam emittance of 0.5 to 1 mm·mrad. The design of a gun capable of producing a beam with an emittance one or two order of magnitude lower than the state of the art would reduce considerably the cost and size of such a FEL. Due to the recent advances in nanotechnologies and vacuum microelectronics, a field-emitter based gun is a promising alternative scheme. We present first measurements on commercial field emitter arrays as well as 3-D numerical simulations of the electron beam dynamics for typical bunch distributions generated from field emitters in realistic gun geometries. The design and some experimental results on a 500kV pulser is also presented.  
Transparencies
 
THP55 Electromagnetic Design of New RF Power Couplers for the S-DALINAC electron, simulation, electromagnetic-fields, linac 736
 
  • M. Kunze, M. Brunken, H.-D. Gräf, W.F.O. Müller, A. Richter, T. Weiland
    TU Darmstadt, Darmstadt
  New rf power couplers for the Superconducting Darmstadt Linear Accelerator (S-DALINAC) injector have to be designed to transfer rf power of up to 2 kW to the electron beam. This allows injector operation at beam currents from 0.15 mA to 0.2 mA and electron energies up to 14 MeV. The new couplers should possibly provide a external Q of 5·106. The transverse kick should be as small as possible. The asymmetric field distribution of the couplers causes emittance growth of the electron beam and therefore the transverse kick has to be minimized. Electromagnetic simulations are applied to investigate different coupler designs and to localize possible problems at an early stage. Cavity external Q and transverse kick can be calculated from 3D electromagnetic eigenmode solutions. The present coaxial-coaxial input couplers at the S-DALINAC are limited to power operation below 500 W under full reflection. In order to reach power operation up to 2 kW a realizations of a low-kick waveguide coupler for the S-DALINAC injector is presented, namely a twin-waveguide coupler.  
Transparencies
 
THP85 Test Results of the 3.9 GHz Cavity at Fermilab damping, coupling, linear-collider, collider 797
 
  • N. Solyak, I. Gonin
    Fermilab, Batavia, Illinois
  • L. Bellantoni, T. Berenc, H. Edwards, M. Foley, N. Khabiboulline, D. Mitchell, A. Rowe
    FNAL, Batavia, Illinois
  Fermilab is developing two types of 3.9 GHz superconducting cavities to improve performances of A0 and TTF photoinjectors. In frame of this project we have built and tested two nine-cell copper models and one 3-cell niobium accelertating cavity and series of deflecting cavities. Properties of the high order modes were carefully studied in a chain of two copper cavities at room temperature. High gradient performance were tested at helium temperature. Achieved gradients and surface resistances are exceed goal parameters. In paper we discuss results of cold tests of the 3-cell accelerating and deflecting cavities.  
 
THP88 Longitudinal Bunch Shape Monitor Using the Beam Chopper of the J-PARC linac, rfq, proton, beam-transport 806
 
  • F. Naito
    KEK, Ibaraki
  We propose the longitudinal bunch shape monitor for the low energy part of the linac of the J-PARC. The monitor uses the beam chopper cavity installled in the MEBT line between thr RFQ and the DTL of the J-PARC as a kind of the bunch rotator. Consequentry the longitudinal bunch shape is measured along the horizontal direction. If we can measure the energy distribution of the bunch also, the longitudinal emittance of the beam is derived. In the paper, the basic idea of the monitor is discussed in detail.  
 
FR101 Overview of Linear Collider Test Facilities and Results linac, collider, linear-collider, damping 827
 
  • H. Hayano
    KEK, Ibaraki
  Linear Collider technology will be recommended by the International Technology Recommendation Panel (ITRP) to the International Linear Collider Steering Committee (ILCSC), soon. Towards this recommendation, many efforts of the developments and the output results of each technology have been made to satisfy the requirements of the technical review committee report (TRC). The test facilities of each linear collider design are the place of the key technology demonstration and realization. The overview of the LC test facilities activities and outputs of TTF, NLCTA, ATF/GLCTA and CTF are summarized and reviewed.  
Transparencies
 
FR102 Muon Ionization Cooling Experiment (MICE) factory, simulation, collider, focusing 832
 
  • M.S. Zisman
    LBNL, Berkeley, California
  There is presently considerable activity worldwide on developing the technical capability for a “neutrino factory” based on a muon storage ring and, a muon collider. Muons are obtained from the decay of pions produced when an intense proton beam hits a high-Z target, so the initial muon beam has a large 6-dimensional phase space. To increase the muons’ phase-space density, we use ionization cooling, which is based on energy loss in an absorber, followed by re-acceleration with high-gradient, normal-conducting RF cavities. The absorber of choice is liquid hydrogen to minimize multiple scattering. A superimposed solenoidal focusing channel contains the muons. Although the physics is straightforward, the technology and its implementation are not. The international MICE collaboration will demonstrate ionization cooling of a muon beam in a short section of a typical cooling channel. The experiment is approved for operation at Rutherford Appleton Lab. We will measure the cooling effects of various absorber materials at various initial emittance values using single-particle counting techniques. The experiment layout and goals will be discussed, along with the status of component R&D.  
Transparencies
 
FR104 Overview on High-Brightness Electron Guns electron, brightness, gun, cathode 842
 
  • J.W. Lewellen
    ANL, Argonne, Illinois
  In an electron storage ring, the quality of the electron beam is generally a function of the ring lattice parameters and has little to do with the source of the electrons. In most electron linear accelerators, the beam brightness is set by the beam source. It is very difficult to improve the overall beam brightness after it has been produced; on the other hand, providing a brighter beam source can provide an “instant upgrade” to the performance of a brightness-limited electron linac-based facility. The development and routine operation of high-brightness guns, therefore, is critical to the success of next-generation linac-based light sources. This includes sources already under construction, such as LCLS, as well as proposed and as-yet completely theoretical machines. In this talk I present a general overview of the state-of-the-art in high-brightness electron beam source development, discuss the concept of “situational brightness”, and highlight some interesting paths towards future devices. I conclude with thoughts on some possible alternate applications for high-brightness beams.  
Transparencies