A   B   C   D   E   F   G   H   I   K   L   M   O   P   Q   R   S   T   U   V   W    

electron

Paper Title Other Keywords Page
MOAA004 RHIC Operational Status luminosity, polarization, proton, ion 358
 
  • T. Roser
    BNL, Upton, Long Island, New York
  Funding: Work was performed under the auspices of the U.S. Department of Energy.

As the first hadron accelerator and collider consisting of two independent superconducting rings RHIC has operated with a wide range of beam energies and particle species. Machine operation and performance will be reviewed that includes high luminosity gold-on-gold and copper-on-copper collisions at design beam energy (100 GeV/u), asymmetric deuteron-on-gold collisions as well as high energy polarized proton-proton collisions (100 GeV on 100 GeV). Plans for future upgrades of RHIC will also be discussed.

 
 
MOAA005 FNAL Tevatron Operational Status antiproton, luminosity, proton, collider 484
 
  • D.P. McGinnis
    Fermilab, Batavia, Illinois
  Funding: Work supported by the Universities Research Assos., Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy.

The Fermilab Tevatron Proton-Antiproton Collider is currently the world’s highest energy hadron collider. The luminosity of the Fermilab collider has been significantly increased with the Main Injector operating at its design goals. Further increases in luminosity have been the result of combining antiprotons from the Recycler and Accumulator storage rings. Recent commissioning of proton slip-stacking in the Main Injector has noticeably increased the antiproton accumulation rate. The increased stacking rate permits the sustained operation of using antiprotons from both the Accumulator and Recycler. Further increases in peak luminosity are expected from electron cooling in the Recycler and increased antiproton flux from the Antiproton Source.

 
 
MOPA002 Performance Limitations in High-Energy Ion Colliders ion, luminosity, heavy-ion, injection 122
 
  • W. Fischer
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886.

High-energy ion colliders (hadron colliders operating with species other than protons) are premier research tools for nuclear physics. The collision energy and high luminosity are important design and operations considerations. However, the experiments also expect flexibility with frequent changes in the collision energy, lattice configuration, and ion species, including asymmetric collisions. For the creation, acceleration, and storage of bright intense ion beams, attention must be paid to space charge, charge exchange, and intra-beam scattering effects. The latter leads to luminosity lifetimes of only a few hours for heavy ions. Ultimately cooling at full energy is needed to overcome this effect. Currently, the Relativistic Heavy Ion Collider at BNL is the only operating high-energy ion collider. The Large Hadron Collider, under construction at CERN, will also run with heavy ions.

 
 
MOPC004 Dynamics of a High Density Ion-Beam with Electron Cooling in HIMAC Synchrotron ion, injection, beam-losses, betatron 416
 
  • T. Uesugi, T. Fujisawa, K. Noda, D. Tann
    NIRS, Chiba-shi
  • Y. Hashimoto
    KEK, Ibaraki
  • I.N. Meshkov, E. Syresin
    JINR, Dubna, Moscow Region
  • S. Ninomiya
    RCNP, Osaka
  • S. Shibuya, H. Uchiyama
    AEC, Chiba
  High density circulating-ion beam was obtained with electron-cooling and cool-stacking injection in HIMAC synchrotron. The ion density was saturated at 1.0e9/cm2. Coherent transverse instability was observed when ion- and electron-beam density was high. The dynamics of the cooled ion-beam are described in this report.  
 
MOPC006 Simulations and Experiments of Beam-Beam Effects in e+e- Storage Rings simulation, luminosity, positron, damping 520
 
  • Y. Cai, J. Seeman
    SLAC, Menlo Park, California
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • K. Ohmi, M. Tawada
    KEK, Ibaraki
  Funding: Work partially supported by the Department of Energy under Contract No. DE-AC02-76SF00515.

Over the past decade, extensive simulations of beam-beam effects in positron-electron collliders, based on the particle-in-cell method, were developed to explain many complex experimental observations. Recently, such simulations were used to predict the future luminosity performance of e+e- colliders. Some predictions have been proven to be correct in the existing accelerators. In this paper, many effects such as dynamic beta, beam-beam limit, crossing angle, parasitic collisions, betatron spectrum, and beam-beam lifetime, will be reviewed from the viewpoints of both simulation and experiment. Whenever possible, direct comparisons between the predictions of the simulation and the corresponding experimental results will be provided.

 
 
MOPC008 Dynamic Beam-Beam Effects Measured at KEKB emittance, beam-beam-effects, positron, luminosity 606
 
  • T. Ieiri, Y. Funakoshi, T. Kawamoto, M. Masuzawa, M. Tobiyama
    KEK, Ibaraki
  Funding: This work is partially supported by Grant-in-Aid Scientific Research (16540271) from Japan Society for the Promotion of Science and Technology.

KEKB is a multi-bunch, high-current, electron/positron collider for B meson physics. The two beams collide at one interaction point (IP) with a finite horizontal crossing angle and with a bunch-space of 6 to 8 ns. The luminosity achieved at KEKB is the best in the world. The betatron tunes are set close to a half integer, to expect the dynamic beam-beam effects that change the beta function around the rings and the emittance as a function of the beam-beam parameter. In order to investigate such attractive beam-beam effects, the beam-beam kick and the beam-beam tune-shift were obtained by comparing the beam parameters between a colliding bunch and a non-colliding one. The horizontal beam size at the IP estimated from a beam-beam kick curve was slightly less than a calculated value without the dynamic effect. The horizontal emittance estimated from the beam-beam tune shift was somewhat larger than a calculated natural emittance. These experimental results reflect the dynamic beam-beam effects.

 
 
MOPC010 Longitudinal Dynamics in the University of Maryland Electron Ring cathode, gun, focusing, longitudinal-dynamics 713
 
  • J.R. Harris, D.W. Feldman, R. Feldman, Y. Huo, J.G. Neumann, P.G. O'Shea, B. Quinn
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: Work supported by the Department of Energy, the Office of Naval Research, the Joint Technology Office, and the Directed Energy Professional Society.

The University of Maryland Electron Ring (UMER) is a low energy electron recirculator for the study of space charge dominated beam transport. The system’s pulse length (100 ns) and large number of diagnostics make it ideal for investigating the longitudinal evolution of intense beams. Pulse shape flexibility is provided by the pulser system and the gridded gun, which has the ability to produce thermionic and photoemission beams simultaneously. In this paper, we report on the generation and evolution of novel line charge distributions in UMER.

 
 
MPPE002 Beam Propagation in Misaligned Magnetic Elements: A MatLab Based Code quadrupole, simulation 826
 
  • T.F. Silva, M.L. Lopes, M.N. Martins, P.B. Rios
    USP/LAL, Bairro Butantan
  Funding: Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESP Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPq.

We present a method to calculate kinematical parameters of a beam subject to a misaligned magnetic element. The procedure consists in transforming the kinematical parameters of the beam to the reference frame in which the magnetic element is aligned, propagating the beam through the element, and transforming back to the original frame. This is done using rotation matrices around the X-, Y-, and Z-axes. These matrices are not Lorentz invariant, so the rotations must be performed in a reference frame where the beam is at rest. We describe the transformation matrices, present a MatLab based code that uses this method to propagate up to 100 particles trough a misaligned quadrupole, and show some graphical outputs of the code.

 
 
MPPE003 Monte Carlo Simulations of Thin Internal Target Scattering In CELSIUS target, simulation, scattering, proton
 
  • Y.-N. Rao
    TRIUMF, Vancouver
  • D. Reistad
    TSL, Uppsala
  In the practical operation of the storage ring CELSIUS with the hydrogen pellet target, we simetimes observe a cooling phenomenon in the longitudinal phase space, that is, the circulating beam's phase space gets shrunk instead of blown up. This phenomenon occurs independently on the electron cooling. In this paper, we aim to investigate and interpret this phenomenon as well as the beam lifetime in the presence of hydrogen pellet target with and without rf and with and without electron cooling in CELSIUS using Monte Carlo simulations.  
 
MPPE031 Simulation of Resonance Streaming at the eRHIC Electron Storage Ring simulation, damping, luminosity, background 2215
 
  • C. Montag
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

To estimate electron beam lifetime and detector background at the future electron-ion collider eRHIC, knowledge of the electron beam halo region is essential. Simulations have been performed to determine the deviation of the transverse beam profile from a Gaussian distribution.

 
 
MPPE066 Streak Camera Studies of Vertical Synchro-Betatron-Coupled Electron Beam Motion in the APS Storage Ring synchrotron, betatron, storage-ring, kicker 3694
 
  • B.X. Yang, M. Borland, W. Guo, K.C. Harkay, V. Sajaev
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38.

We present experimental studies of synchro-betatron-coupled electron beam motion in the Advanced Photon Source storage ring. We used a vertical kicker to start the beam motion. When the vertical chromaticity is nonzero, electrons with different initial synchrotron phases have slightly different betatron frequencies from the synchronous particle, resulting in a dramatic progression of bunch-shape distortion. Depending on the chromaticity and the time following the kick, images ranging from a simple vertical tilt in the bunch to more complicated twists and bends are seen with a visible light streak camera. Turn-by-turn beam position monitor data were taken as well. We found that the experimental observations are well described by the synchro-betatron-coupled equations of motion. We are investigating the potential of using the tilted bunch to generate picosecond x-ray pulses. Also note that the fast increase in vertical beam size after the kick is dominated by the internal synchro-betatron-coupled motion of the electron bunch. Experimentally this increase could be easily confused with decoherence of vertical motion if the bunch is only imaged head-on.

 
 
MPPE067 Refined Calculation of Beam Dynamics During UMER Injection dipole, injection, simulation, quadrupole 3733
 
  • G. Bai, S. Bernal, T.F. Godlove, I. Haber, R.A. Kishek, P.G. O'Shea, B. Quinn, J.C. Tobin Thangaraj, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by U.S. Dept. of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

The University of Maryland Electron Ring (UMER) is built as a low-cost testbed for intense beam physics for benefit of larger ion accelerators. The beam intensity is designed to be variable, spanning the entire range from low current operation to highly space-charge-dominated transport. The ring has recently been closed and multi-turn commissioning has begun. Although we have conducted many experiments at high space charge during UMER construction, lower-current beams have become quite useful in this commissioning stage for assisting us with beam steering, measurement of phase advance, etc. One of the biggest challenges of multi-turn operation of UMER is correctly operating the Y-shaped injection section, hence called the Y-section, which is specially designed for UMER multi-turn operation. It is a challenge because the system requires several quadrupoles and dipoles in a very stringent space, resulting in mechanical, electrical, and beam control complexities. This paper presents a simulation study of the beam centroid motion in the injection region.

 
 
MPPE073 Effects of the Passive Harmonic Cavity on the Beam Bunch radiation, synchrotron, beam-loading, impedance 3904
 
  • L.-H. Chang, M.-C. Lin, C. Wang, M.-S. Yeh
    NSRRC, Hsinchu
  In this paper, we present a computer tracking code, which can investigate the bunch length, energy spread and the critical current of Robinson instability under the influence of the passive harmonic cavity. The effects of the radiation damping, quantum excitation and the beam loading of the harmonic cavity are included in the computation. The calculated result shows that the beam has a constant energy spread and blows up as the beam current increases from below to over the threshold current of the Robinson instability. It also indicates that the shunt impedance of the harmonic cavity is critical for whether the harmonic cavity can reach the designed goal, a stable and lengthening beam at the design beam current.  
 
MPPE076 Design Study on a New Separator for PEEM3 quadrupole, optics, focusing, dipole 3985
 
  • W. Wan, J. Feng, H.A. Padmore
    LBNL, Berkeley, California
  Funding: Work supported by the Director, Office of Energy Research, Office of Basic Energy Science, Material Sciences Division, U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.

A new aberration-corrected Photoemission Electron Microscope, called PEEM3, is under development at the Advanced Light Source. The resolution and transmission improvement is realized by correcting the lowest order spherical and chromatic aberrations using an electron mirror. A separator is required to separate the incoming uncorrected electron beam to the mirror from the corrected outgoing electron beam to the projector column. In this paper, we present a design study of a new separator for PEEM3. The layout, the Gaussian optics, the analysis of aberrations and the tolerance on power supply stability and alignment errors are reported.

 
 
MPPE080 Transversal Deflection of Electrons Moving in Parallel with Linearly Polarized Laser Beam and its Application laser, interaction-region, photon, polarization 4054
 
  • D.A. Zakaryan, D.K. Kalantaryan
    YSU, Yerevan
  • E.D. Gazazyan, K.A. Ispirian, M.K. Ispirian
    YerPhI, Yerevan
  The motion of electrons in linearly polarized laser beams in a finite length interaction region and after in a field free drift length is investigated. It is shown that in the interaction region the trajectory of the electrons is almost straight lines with very small oscillation weakly depending on the laser intensity. In the drift region the electrons acquire significant transversal deflection that allows to carry out the measurement of the length and longitudinal particle distribution of femtosecond bunches. The dependence of this deflection upon the electron energy, interaction region length, etc is studied. The principles of the construction of femtosecond oscilloscopes are discussed.  
 
MPPP008 Equilibrium Beam Invariants of an Electron Storage Ring with Linear x-y Coupling resonance, damping, coupling, betatron 1111
 
  • J. Wu, A. Chao, B. Nash
    SLAC, Menlo Park, California
  Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.

In accelerator systems, it is very common that the motion of the horizontal plane is coupled to that of the vertical plane. Such coupling will induce tune shifts and can cause instabilities. The damping and diffusion rates are also changed, which in turn will lead to a change in the equilibrium invariants. Following the perturbative approach which we developed for synchrobetatron coupling,* we study the x-y coupled case in this paper. Starting from the one turn map, we give explicit formulae for the tune shifts, damping and diffusion rates, and the equilibrium invariants. We focus on the cases where the system is near the integer or half integer, and sum or difference resonances where small coupling can cause a large change in the beam distribution.

*B. Nash, J. Wu, and A. Chao, work in progress.

 
 
MPPP009 Linac Coherent Light Source Longitudinal Feedback Model feedback, linac, simulation, gun 1156
 
  • J. Wu, P. Emma, L. Hendrickson
    SLAC, Menlo Park, California
  Funding: Work is supported by the US Department of Energy under contract DE-AC02-76SF00515.

The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL). To ensure the vitality of FEL lasing, it is critical to preserve the high quality of the electron beam during acceleration and compression. The peak current and final energy are very sensitive to system jitter. To minimize this sensitivity, a longitudinal feedback system on the bunch length and energy is required, together with other diagnostics and feedback systems (e.g., on transverse phase space). In this paper, we describe a simulation framework, which includes a realistic jitter model for the LCLS accelerator system, the RF acceleration, structure wakefield, and second order optics. Simulation results show that to meet the tight requirements set by the FEL, such a longitudinal feedback system is mandatory.

 
 
MPPP019 Beam Orbit Diagnostics and Control in CANDLE Storage Ring photon, diagnostics, closed-orbit, storage-ring 1655
 
  • G.A. Amatuni, Y.L. Martirosyan, R.H. Mikaelyan, V.M. Tsakanov, A. Vardanyan
    CANDLE, Yerevan
  Stability requirements for the CANDLE light source are the consequence of a small electron beam size and a tolerable photon beam parameters. In a real machine, the components of the storage ring have static and dynamic imperfections, which cause disturbance of the electron beam and consequently photon beams parameters. In the present paper the basic approaches to the beam diagnostics, control and correction issues for the CANDLE facility are given. The algorithms, electronics and processing hardware are described.  
 
MPPP024 Recent Observations on a Horizontal Instability in the DAFNE Positron Ring feedback, positron, damping, impedance 1841
 
  • A. Drago, M. Zobov
    INFN/LNF, Frascati (Roma)
  • D. Teytelman
    SLAC, Menlo Park, California
  A strong horizontal instability limits the maximum positron current storable in the DAFNE Phi-Factory. A powerful feedback system makes it possible to store and collide up to 1250 mA of positron current in 105 bunches. Nevertheless, a much higher current (> 2.4A) has been successfully stored in the twin electron ring. Measurements have been carried out to understand the positron current limit and to characterize the behavior of the horizontal instability at high current with different bunch patterns. Grow/damp turn-by-turn data obtained by turning off the horizontal feedback have been acquired and analyzed. Spectral analysis and grow rates of the instability are shown. In particular, the -1 mode has strong evidence and fast grow rate. Its grow rate behavior is analyzed at different beam currents and bunch patterns.  
 
MPPP025 The Impedance of the Ceramic Chamber in J-PARC impedance, space-charge, multipole 1898
 
  • Y. Shobuda
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • Y.H. Chin, K. Ohmi, T. Toyama
    KEK, Ibaraki
  The ceramic chamber is adopted at the RCS (rapid cycling synchrotron) in J-PARC. The copper stripes are on the outer surface of the chamber in order to shield the electro-magnetic field produced by the beam. The inner surface of the chamber is coated by TiN to suppress the secondary electron emission. In this paper, we calculate the strength of electro-magnetic field produced by the beam and evaluate the impedance of this ceramic chamber.  
 
MPPP028 The Code MBIM1 for the Calculation of the Multibunch Beams Coherent Oscillations Stability (in Approach of Short Bunches) synchrotron, multipole, storage-ring, positron 2009
 
  • N. Mityanina
    BINP SB RAS, Novosibirsk
  The code MBIM1 for the calculation of the coherent oscillations stability for multibunch beams in storage rings is presented. The multibunch beams with arbitrary charges of bunches are considered, including counterrotating bunches (in approach of short bunches in comparison with minimal wavelength of considered environment RF spectrum), with the account of beams coupling with the environment (i.e. RF cavities or/and smooth vacuum chamber with walls of finite conductivity). The code uses the approach of small shifts of coherent frequencies, when different multipole types of synchrotron oscillations can be treated as independent from each other.  
 
MPPP031 The CERN-SPS Experiment on Microwave Transmission Through the Beam Pipe cyclotron, resonance, injection, dipole 2212
 
  • T. Kroyer, T. Kroyer
    TU Vienna, Vienna
  • F. Caspers, E. Mahner
    CERN, Geneva
  Funding: Ministry for Education, Science and Culture, Austria.

In the CERN SPS microwave transmission measurements through beampipe sections with a length of 30 m and 7 m meter respectively have been carried out in the frequency range 2-4 GHz since spring 2003. Here we report on new results obtained with improved measurement techniques during the 2004 run. Observation techniques include a fast real time scope, spectrum analyser IF and video output signal registration and baseband signal observation using a PC soundcard. The unexpected beam induced amplitude modulation has been confirmed on all kinds of available beams including single bunches. It was found that there is a correlation between the amount of beam induced signal attenuation and the beam losses registered by external scintillators. Potential theoretical models are discussed.

 
 
MPPP035 Investigation of APS PAR Vertical Beam Instability ion, injection, linac, synchrotron 2393
 
  • C. Yao, Y.-C. Chae, N. Sereno, B.X. Yang
    ANL, Argonne, Illinois
  Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The Advanced Photon Source (APS) particle accumulator ring (PAR) is a 325-MeV storage ring that collects and compresses linac pulse trains into a single bunch for booster injection. A vertical beam instability has been observed when only a single linac bunch is injected and the total beam charge is from 0.15 to 0.7 nC. The instability starts about 80 ms after the injection, lasts about 160 ms, and is highly reproducible. We performed spectral measurement and time-resolved imaging with both a gated-intensified camera and a streak camera in order to characterize this instability. Initial analysis of the data indicates that the instability is due to ion trapping. A stable lattice was established as result of the investigation. This report summarizes the experimental results and gives some preliminary analysis.

 
 
MPPP046 Transient Resistive Wall Wake for Very Short Bunches vacuum, laser 2926
 
  • G.V. Stupakov
    SLAC, Menlo Park, California
  Funding: Work supported by U.S. Department of Energy, contract DE-AC03-76SF00515.

The catch up distance for the resistive wall wake in a round pipe is approximately equal to the square of the pipe radius divided by the bunch length. The standard formulae for this wake are applicable at distances much larger than the catch up distance. For extremely short bunches, considered recently by Zholents and Fawley in application for SASE (PRL, vol. 92, p. 224801), this formation length can be tens of meters. In this paper, we calculate the resistive wall wake for such a beam at distances compared with the catch up distance assuming a constant wall conductivity. We also discuss how the derivation can be modified to include the frequency dependence of the conductivity characteristic for very short wavelength.

 
 
MPPP049 Observations and Measurements of Anomalous Hollow Electron Beams in a Storage Ring lattice, storage-ring, single-bunch, betatron 3082
 
  • Y.K. Wu, J. Li
    DU/FEL, Durham, North Carolina
  • J. Wu
    SLAC, Menlo Park, California
  Funding: This work is supported by the U.S. AFOSR MFEL grant F49620-001-0370 and by U.S. DOE grant DE-FG05-91ER40665 (YW and JL). This work is also supported by U.S. DOE contract DE-AC02-76SF00515 (JW).

This paper reports first observations and measurements of anomalous hollow electron beams in a storage ring. In a lattice with a negative chromaticity, hollow electron beams consisting of a solid core beam inside and a large ring beam outside have been created and studied in the Duke storage ring. We report the detailed measurements of the hollow beam phenomenon, including its distinct image pattern, spectrum signature, and its evolution with time. By capturing the post-instability bursting beam, the hollow beam is a unique model system for studying the transverse instabilities, in particular, the interplay of the wake field and the lattice nonlinearity. In addition, the hollow beam can be used as a powerful tool to study the linear and nonlinear particle dynamics in the storage ring.

 
 
MPPT027 Three-Dimensional Design of a Non-Axisymmetric Periodic Permanent Magnet Focusing System focusing, beam-transport, permanent-magnet, simulation 1964
 
  • C. Chen, R. Bhatt, A. Radovinsky, J.Z. Zhou
    MIT/PSFC, Cambridge, Massachusetts
  Funding: Work supported by the MIT Deshpande Center for Technological Innovation, the U.S. Department of Energy, High-Energy Physics Division, Grant No. DE-FG02-95ER40919, and the Air Force Office of Scientific Research, Grant No. F49620-03-1-0230.

A three-dimensional (3D) design is presented of a non-axisymmetric periodic permanent magnet focusing system which will be used to focus a large-aspect-ratio, ellipse-shaped, space-charge-dominated electron beam. In this design, an analytic theory is used to specify the magnetic profile for beam transport. The OPERA3D code is used to compute and optimize a realizable magnet system. Results of the magnetic design are verified by two-dimensional particle-in-cell and three-dimensional trajectory simulations of beam propagation using PFB2D and OMNITRAK, respectively. Results of fabrication tolerance studies are discussed.

 
 
MPPT032 Construction and Performance of Superconducting Magnets for Synchrotron Radiation wiggler, radiation, multipole, synchrotron 2218
 
  • C.-S. Hwang, C.-H. Chang, C.-K. Chang, H.-P. Chang, C.-T. Chen, H.-H. Chen, J. Chen, J.-R. Chen, Y.-C. Chien, T.-C. Fan, G.-Y. Hsiung, K.-T. Hsu, S-N. Hsu, M.-H. Huang, C.-C. Kuo, F.-Y. Lin
    NSRRC, Hsinchu
  Two superconducting magnets, one wavelength shifter (SWLS) with a field of 5 T and one wiggler (SW6) with a field of 3.2 T, were constructed and routinely operated at NSRRC for generating synchrotron x-rays. In addition, three multipole wigglers (IASW) with fields of 3.1 T will be constructed and installed each in the three achromatic short straight sections. A warm beam duct of 20 mm inner gap and a 1.5 W GM type cryo-cooler were chosen for the SWLS to achieve cryogen-free operation. For the SW6, a cold beam duct of 11 mm inner gap was kept at 100 K temperature and no trim coil compensation is necessary for its operation. Meanwhile, no beam loss was observed when the SW6 was quenched. A cryogenic plant with cooling power of 450 W was constructed to supply the liquid helium for the four superconducting wigglers. The design concept, magnetic field quality, the commissioning results, and the operation performance of these magnets will be presented.  
 
MPPT033 Development of a Superconducting Helical Undulator for a Polarised Positron Source undulator, positron, linear-collider, collider 2295
 
  • Y. Ivanyushenkov, F.S. Carr
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • D.P. Barber
    DESY, Hamburg
  • E. Baynham, T.W. Bradshaw, J. Rochford
    CCLRC/RAL, Chilton, Didcot, Oxon
  • J.A. Clarke, O.B. Malyshev, D.J. Scott, B.J.A. Shepherd
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. Cooke, J.B. Dainton, T. Greenshaw
    Liverpool University, Science Faculty, Liverpool
  • G.A. Moortgat-Pick
    Durham University, Durham
  A method of producing a polarised positron beam from e+e- pair production in a target by circularly polarised ?-radiation is being investigated. Polarised photons are to be generated by the passage of a high energy electron beam (250 GeV as anticipated in the International Linear Collider - ILC) through a helical undulator. For production of 20 MeV photons, an undulator with a period of 14 mm, a bore of approximately 4 mm and magnetic field on axis of 0.75 T is required. First prototypes have been constructed using both superconducting and permanent magnet technologies which are capable of producing the necessary magnetic field configuration in the undulator. This paper details the design, construction techniques and field measurement results of the first superconducting prototype and compares the results with simulation.  
 
MPPT036 R&D of Short-Period NbTi and Nb3Sn Superconducting Undulators for the APS undulator, vacuum, photon, injection 2419
 
  • S.H. Kim, C. Doose, R. Kustom, E.R. Moog, I. Vasserman
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. W-31-109-ENG-38.

A superconducting undulator (SCU) with a period of 14.5 mm is under development at the Advanced Photon Source (APS). The undulator is designed to achieve a peak field on the beam axis of 0.8 T with an 8 mm pole gap and an average current density of 1 kA/mm2 in the NbTi coil. A 22-period half-section of a SCU has been fabricated. The SCU half-section was charged up to near the average critical current density jc of 1.4 kA/mm2, and the stability margin was measured by imposing external heat fluxes on the coil at 4.2 K in pool boiling LHe. The magnetic fields along the midplane of the SCU were measured using a Hall-probe field-mapping unit installed in a vertical dewar. The first test of a Nb3Sn short-section SCU reached an average current density of 1.45 kA/mm2, slightly higher than the jc for the NbTi SCU.

 
 
MPPT063 Optimized Analyzing Magnet for Measurements of Polarization of Gamma-Quants at 10 MeV polarization, target, positron, scattering 3582
 
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  We described here calculations and test of magnet for measurement of polarization of gammas by its helicity-dependent attenuation in magnetized iron. Magnet is a compact device which size is ~ten times smaller, than world wide analogues.  
 
MPPT077 Radiation of Electron in the Field of Plane Light Wave radiation, laser, scattering, photon 3997
 
  • A.Y. Zelinsky, I.V. Drebot, Yu.N. Grigor'ev, O.D. Zvonarjova
    NSC/KIPT, Kharkov
  • R. Tatchyn
    SLAC, Menlo Park, California
  In the work the process of electron interaction with field of oncoming light wave (Compton scattering) has been considered with methods of classical electrodynamics. As results of Lorenz equation integration the trajectories of electron motion in the wave field were derived. On the base of obtained results the expressions for electron radiation spectrum were produced.In the work dependences of spectrum shape on electron and photon beams parameters are analyzed.  
 
MPPT079 Commissioning of an APPLE-II Undulator at Daresbury Laboratory for the SRS undulator, insertion-device, photon, insertion 4051
 
  • J.A. Clarke, F.E. Hannon, D.J. Scott, B.J.A. Shepherd, N.G. Wyles
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  A new variable polarisation undulator of the APPLE-II type has been designed and constructed at Daresbury Laboratory. Initial magnet testing of the 56mm period device was followed by an intensive period of shimming to improve the field quality. After this was successfully completed the undulator was installed into the SRS and tests made of the effect of the device upon the electron beam. This beam commissioning was completed in a very short space of time with the beamline being given full control of the gap and phase of the magnet within a few weeks of installation. This paper summarises the measurement of the magnet and the shimming techniques employed to improve the field quality. It also describes the effect of the device upon the stored 2 GeV electron beam and the measures taken to minimise these effects during user operations.  
 
MPPT082 The 8 cm Period Electromagnetic Wiggler Magnet with Coils Made from Sheet Copper wiggler, power-supply, undulator, klystron 4093
 
  • G.H. Biallas, S.V. Benson, T. Hiatt, G. Neil, M.D. Snyder
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by the US DOE Contract #DE-AC05-84ER40150, the Office of Naval Research, the Air Force Research Laboratory, the U.S. Army Night Vision Laboratory and the Commonwealth of Virginia.

An electromagnetic wiggler, now lasing at the Jefferson Lab FEL, has 29 eight cm periods with K variable from 0.6 to1.1 and gap of 2.6 cm. The wiggler was made inexpensively in 11 weeks by an industrial machine shop. The conduction cooled coil design uses copper sheet material cut to forms using water jet cutting. The conductor is cut to serpentine shapes and the cooling plates are cut to ladder shape. The sheets are assembled in stacks insulated with polymer film, also cut with water jet. The coil design extends the serpentine conductor design of the Duke OK4 to more and smaller conductors. The wiggler features graded fields in the two poles at each end and trim coils on these poles to eliminate field errors caused by saturation. An added critical feature is mirror plates at the ends with integral trim coils to eliminate three dimensional end field effects and align the entrance and exit orbit with the axis of the wiggler. Details of construction, measurement methods and excellent wiggler performance are presented.

 
 
MPPT083 Radiation Damage to Advanced Photon Source Undulators radiation, undulator, vacuum, synchrotron 4126
 
  • S. Sasaki, C. Doose, E.R. Moog, M. Petra, I. Vasserman
    ANL, Argonne, Illinois
  • N.V. Mokhov
    Fermilab, Batavia, Illinois
  Funding: Supported by the U.S. DOE Office of Science under Contract No. W-31-109-ENG-38.

Radiation-induced magnetic field strength losses are seen in undulator permanent magnets in the two sectors with small-aperture (5 mm) vacuum chambers. Initially, simple retuning of the affected undulators could restore them to full operation. As the damage has accumulated, however, it has become necessary to disassemble the magnetic arrays and either replace magnet blocks or remagnetize and reinstall magnet blocks. Some of the damaged magnet blocks have been studied, and the demagnetization was found to be confined to a limited volume at the surface close to the electron beam. Models for the magnetic damage were calculated using RADIA* and were adjusted to reproduce the measurements. Results suggest that a small volume at the surface has acquired a weak magnetization in the opposite direction. Small magnet samples provided by NEOMAX and Shin-Etsu are being placed in the storage ring tunnel for irradiation exposure testing. Simulations of the radiation environment at the undulators have been performed.

*O. Chubar, P. Elleaume, J. Chavanne, J. Synchrotron Radiat. 5, 481 (1998).

 
 
MPPT085 Fast Magnets for the NSLS-II Injection injection, kicker, septum, storage-ring 4165
 
  • I.P. Pinayev, T.V. Shaftan
    BNL, Upton, Long Island, New York
  Funding: Under Contract with the U.S. Department of Energy Contract Number DE-AC02-98CH10886.

Third generation light sources require top-off operation in order to provide proper stability of the photon beam. In this paper we present the conceptual design of the fast pulsed magnets used for injection into the 3 GeV storage ring.

 
 
MOPB002 High Intensity High Charge State ECR Ion Sources ion, ion-source, plasma, emittance 179
 
  • D. Leitner, C.M. Lyneis
    LBNL, Berkeley, California
  Funding: This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Nuclear Physics Division of the U.S. Department of Energy under Contract DE AC03-76SF00098.

The next-generation heavy ion beam accelerators such as the proposed Rare Isotope Accelerator (RIA), the Radioactive Ion Beam Factory at RIKEN, the GSI upgrade project, the LHC-upgrade, and IMP in Lanzhou require a great variety of high charge state ion beams with a magnitude higher beam intensity than currently achievable. High performance Electron Cyclotron Resonance (ECR) ion sources can provide the flexibility since they can routinely produce beams from hydrogen to uranium. Over the last three decades, ECR ion sources have continued improving the available ion beam intensities by increasing the magnetic fields and ECR heating frequencies to enhance the confinement and the plasma density. With advances in superconducting magnet technology, a new generation of high field superconducting sources is now emerging, designed to meet the requirements of these next generation accelerator projects. The talk will briefly review the field of high performance ECR ion sources and the latest developments for high intensity ion beam production. The currently most advanced next-generation superconducting source ECR ion source VENUS will be described in more detail.

 
 
MOPB004 Progress on Test EBIS and the Design of an EBIS-Based RHIC Preinjector ion, cathode, injection, gun 363
 
  • J.G. Alessi, E.N. Beebe, O. Gould, A. Kponou, R. Lockey, A.I. Pikin, K. Prelec, D. Raparia, J. Ritter, L. Snydstrup
    BNL, Upton, Long Island, New York
  Funding: Work supported under the auspices of the U.S. DOE.

Following the successful development of the Test EBIS at BNL,* we now have a design for an EBIS-based heavy ion preinjector which would serve as an alternative to the Tandem Van de Graaffs in providing beams for RHIC and the NASA Space Radiation Laboratory. This baseline design includes an EBIS producing mA-level currents of heavy ions (ex. Au 32+) in ~ 10-20 microsecond pulses, injecting into an RFQ which accelerates the beams to 300 keV/amu, followed by an IH linac accelerating to 2 MeV/amu. Some details of this design will be presented, as well recent experimental results on the Test EBIS.

*E.N. Beebe et al., Proc. Ninth International Symposium on Electron Beam Ion Sources and Traps, Journal of Physics: Conference Series 2 (2004) 164–173.

 
 
MOPB006 Frontiers of RF Photoinjectors emittance, laser, gun, cathode 530
 
  • M. Ferrario
    INFN/LNF, Frascati (Roma)
  New ideas have been recently proposed to achieve ultra-high brightness electron beams, as particularly needed in SASE-FEL experiments, and to produce flat beams, as required in linear colliders. Low emittance schemes already foreseen for split normal conducting photoinjectors have been applied to the superconducting case in order to produce high peak and high average beam brightness. RF compressor techniques have been partially confirmed by experimental results and more compact RF photoinjector designs including compression scheme are under development. Research and experiments in the flat beam production from a photoinjector as a possible alternative to damping rings are in progress. An overview of recent advancements and future perspectives in photoinjector beam physics is reported in this talk.  
 
MOPB007 Future Directions in Electron Sources cathode, focusing, emittance, gun 563
 
  • J.W. Lewellen
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The emittance-compensated rf photoinjector is in the process of evolving from an experiment in and of itself, to a laboratory instrument, to a workhorse component of large user facilities such as next-generation light sources. In recent years the performance achieved by the standard p-mode design has approached the levels predicted by theory and experiment. The basic design has been scaled from X-band down to less than 1 GHz in terms of operating frequency, and superconducting designs are presently undergoing initial testing at various locations. The requirements for linac-based light sources will require at least one order of magnitude improvement in beam quality; other applications, such as electron microscopes or high-energy electron lithography, require still greater improvements. The migration towards fully superconducting accelerators provides some additional design challenges. This paper briefly presents requirements for some future applications, and presents four new approaches to extending injector performance: the diamond-emitter photocathode, the planar focusing cathode, the magnetic-mode emittance compensation technique, and the field-emission-gated cathode.

 
 
MOPB008 Temporal E-Beam Shaping in an S-Band Accelerator laser, emittance, linac, diagnostics 642
 
  • H. Loos, D. Dowell, A. Gilevich, C. Limborg-Deprey
    SLAC, Menlo Park, California
  • M. Boscolo, M. Ferrario, M. Petrarca, C. Vicario
    INFN/LNF, Frascati (Roma)
  • J.B. Murphy, B. Sheehy, Y. Shen, T. Tsang, X.J. Wang, Z. Wu
    BNL, Upton, Long Island, New York
  • L. Serafini
    INFN-Milano, Milano
  Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contracts DE-AC02-98CH10886 and DE-AC03-76SF00515.

New short-wavelength SASE light sources will require very bright electron beams, brighter in some cases than is now possible. One method for improving brightness involves the careful shaping of the electron bunch to control the degrading effects of its space charge forces. We study this experimentally in an S-band system, by using an acousto-optical programmable dispersive filter to shape the photocathode laser pulse that drives the RF photoinjector. We report on the efficacy of shaping from the IR through the UV, and the effects of shaping on the electron beam dynamics.

 
 
MOPB009 Review of the Production Process of TTF and PITZ Photocathodes cathode, gun, monitoring, linac 671
 
  • D. Sertore, P. Michelato, L. Monaco
    INFN/LASA, Segrate (MI)
  • A. Bonucci
    SAES Getters S.p.A., Lainate
  • J.H. Han
    DESY Zeuthen, Zeuthen
  • S. Schreiber
    DESY, Hamburg
  In the present article, the production process of the photocathodes for the TESLA Test Facility (TTF) at DESY Hamburg and the Photo Injector Test Facility at DESY-Zeuthen (PITZ) is reviewed in order to highlight key elements for the final photocathode performances. Since the first photocathode production in 1998, we have continuosly collected relevant paramenters of the cathode plugs and deposition process. These data are now critically analized in view of an optimization of the photocathode performances for the next generation of high brilliance sources.  
 
MOPB010 Simulations and Experiments of Electron Beams Pre-Modulated at the Photocathode simulation, laser, radiation, space-charge 704
 
  • J.G. Neumann, R.B. Fiorito, P.G. O'Shea
    IREAP, College Park, Maryland
  • G.L. Carr, T.V. Shaftan, B. Sheehy, Y. Shen, Z. Wu
    BNL, Upton, Long Island, New York
  • W. Graves
    MIT, Middleton, Massachusetts
  • H. Loos
    SLAC, Menlo Park, California
  Funding: Work is supported by the Office of Naval Research, the Joint Technology Office, and the Department of Energy.

The University of Maryland and the Source Development Laboratory at Brookhaven National Laboratory have been collaborating on a project that explores the use of electron beam pre-modulation at the cathode to control the longitudinal structure of the electron beam. This technique could be applied to creating deliberate modulations which can lead to the generation of terahertz radiation, or creating a smooth profile in order to supress radiation. This paper focuses on simulations that explore some of the pre-modulated cases achieved experimentally.

 
 
MOPB011 Axial RF Power Input in Photocathode Electron Guns cathode, gun, emittance, superconducting-RF 743
 
  • D. Janssen
    FZR, Dresden
  • H. Bluem, A.M.M. Todd
    AES, Princeton, New Jersey
  • V. Volkov
    BINP SB RAS, Novosibirsk
  We discuss the coaxial power input in normal and superconducting RF (SRF)photoinjector cavities. Upstream coaxial power input has been previously used at the PITZ facility where the output beam tube is an intrinsic part of the coaxial transmission line into the gun. In this paper, we describe coaxial coupling from the cathode side of the gun. For normal conducting RF guns, in addition to the advantage from symmetric coupling, an emittance compensation solenoid can now be positioned close to the gun cavity to deliver optimal transverse emittance. Beam dynamics calculations demonstrate 0.8 mm-mrad at 1 nC in X-band. For an SRF gun, we present a design for coaxial input around the cathode using a superconducting coupling cell. This cell matches the external quality factor of the gun for different beam powers and there is no RF loss associated with the axial gap of the cathode. The heat input into the coaxial feed and the surface field of the coupler are discussed. For a 1.3 GHz half-cell gun cavity with stored energy of 6.6 J, a 2.5 MeV electron beam can be delivered with a peak accelerating field of 50 MV/m. At 10 mA,the external Q is 2.1 x 106 and the coaxial line power loss that must be cooled is 28 W.  
 
TOAC005 Coherent Synchrotron Radiation as a Diagnostic Tool for the LCLS Longitudinal Feedback System radiation, feedback, synchrotron, synchrotron-radiation 428
 
  • J. Wu, P. Emma, Z. Huang
    SLAC, Menlo Park, California
  Funding: Work is supported by the US Department of Energy under contract DE-AC02-76SF00515.

The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL). To ensure the vitality of FEL lasing, a longitudinal feedback system is required together with other diagnostics. In this paper, we study the possibility of using Coherent Synchrotron Radiation (CSR) from the chicane as the diagnostic tool for bunch length feedback. Calculations show that CSR is a good candidate, even for the non-Gaussian, double-horn longitudinal charge distribution. We further check the feasibility for low and high charge options, and also the possibility for detecting the microbunching.

 
 
TOAA003 Survey of Superconducting Insertion Devices for Light Sources wiggler, undulator, multipole, radiation 256
 
  • N.A. Mezentsev, E. Perevedentsev
    BINP SB RAS, Novosibirsk
  The first Superconducting Insertion devices were designed, fabricated and installed on electron storage rings more than 25 years ago for generation of synchrotron radiation. For these years wide experience of manufacturing and use of such superconducting insertion devices as superconducting wave length shifters, multipolar wigglers and undulators is accumulated. Review of various types of Superconducting Insertion Devices for Light Sources is given in the report. Their basic characteristics as SR sources are discussed.  
 
TPAE001 Experiments on Wake Field Acceleration in Plasma and the Program of the Further Works in YerPhI plasma, acceleration, laser, vacuum 752
 
  • M.L. Petrosyan, M. Akopov, Y.A. Garibyan, E.M. Laziev, R.A. Melikian, Y. Nazaryan, M.K. Oganesyan, G.M. Petrosyan, L.M. Petrosyan, V.S. Pogosyan, G.K. Tovmasyan
    YerPhI, Yerevan
  Funding: ISTC, Project A-405.

The use of wake field acceleration basically is aimed to obtaining of high acceleration rate in comparison with traditional methods of acceleration. Meantime in the last years in YerPhI it was offered to use wake field acceleration for acceleration of high-current electron bunches on energy about 100 MeV. Experimental installation for research of formation of high-current electron bunches of the given configuration, necessary for wake field acceleration and acceleration of these bunches in plasma is created. The installation is intended for acceleration of electron bunches with a current of few tens amperes and up to energy 1-2 MeV. For excitation of wake waves in plasma the electron accelerator of direct action with use of high-voltage pulse transformer is used. Results of researches have revealed some properties of formation of high-current bunches, especially restrictions of a electron current because of space charge effects at sub-picoseconds duration of bunches. The basic parameters of the wake field acceleration project on energy about 100 MeV are given, taking into account results of researches on experimental installation.

 
 
TPAE002 The Project PLASMONX for Plasma Acceleration Experiments and a Thomson X-Ray Source at SPARC laser, plasma, acceleration, simulation 820
 
  • L. Serafini, F. Alessandria, A. Bacci, I. Boscolo, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, M. Mauri, V. Petrillo, R. Pozzoli, M. Rome
    INFN-Milano, Milano
  • D. Alesini, M. Bellaveglia, S. Bertolucci, M.E. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, M.  Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M.A. Preger, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
    INFN/LNF, Frascati (Roma)
  • W. Baldeschi, A. Barbini, M. Galimberti, A. Giulietti, A. Gizzi, P. Koester, L. Labate, A. Rossi, P. Tommasini
    CNR/IPP, Pisa
  • R. Bonifacio, N. Piovella
    Universita' degli Studi di Milano, MILANO
  • U. Bottigli, B. Golosio, P.N. Oliva, A. Poggiu, S. Stumbo
    INFN-Cagliari, Monserrato (Cagliari)
  • F. Broggi
    INFN/LASA, Segrate (MI)
  • C.A. Cecchetti, D. Giulietti
    UNIPI, Pisa
  We present the status of the activity on the project PLASMONX, which foresees the installation of a multi-TW Ti:Sa laser system at the CNR-ILIL laboratory to conduct plasma acceleration experiments and the construction of an additional beam line at SPARC to develop a Thomson X-ray source at INFN-LNF. After pursuing self-injection experiments at ILIL, when the electron beam at SPARC will be available the SPARC laser system will be upgraded to TW power level in order to conduct either external injection plasma acceleration experiments and ultra-bright X-ray pulse generation with the Thomson source. Results of numerical simulations modeling the interaction of the SPARC electron beam and the counter-propagating laser beam are presented with detailed discussion of the monochromatic X-ray beam spectra generated by Compton backscattering: X-ray energies are tunable in the range 20 to 1000 keV, with pulse duration from 30 fs to 20 ps. Preliminary simulations of plasma acceleration with self-injection are illustrated, as well as external injection of the SPARC electron beam. The proposed time schedule for this initiative is finally shown, which is tightly correlated with the progress of the SPARC project.  
 
TPAE003 Numerical Study of Injection Mechanisms for Generation of Mono-Energetic Femtosecond Electron Bunch from the Plasma Cathode plasma, laser, injection, acceleration 859
 
  • T. Ohkubo, M. Uesaka, G. Zhidkov
    UTNL, Ibaraki
  Acceleration gradients of up to the order of 100GV/m and mono-energetic electron bunch up to 200MeV have recently been observed in several plasma cathode experiments. However, mechanisms of self-injection in plasma are not sufficiently clarified, presently. In this study, we carried out 2D PIC simulation to reveal the mechanisms of mono-energetic femtosecond electron bunch generation. We found two remarkable conditions for the generation: electron density gradient at vacuum-plasma interface and channel formation in plasma. Steep electron density gradient (~ plasma wave length) causes rapid injection and produces an electron bunch with rather high charge and less than 100fs duration. The channel formation guides an injected laser pulse and decreases the threshold of laser self-focusing, which leads to high electric field necessary for wave-breaking injection.  
 
TPAE005 Generation of Small Energy Spread Electron Beam from Self-Modulated Laser Wakefield Accelerator plasma, laser, ion, space-charge 976
 
  • C. Kim, I.S. Ko
    POSTECH, Pohang, Kyungbuk
  • N. Hafz, G.-H. Kim, H. Suk
    KERI, Changwon
  Funding: The authors are grateful for financial support from the Korean Ministry of Science and Technology through the Creative ResearchInitiatives Program.

Laser and plasma based accelerators have been studied for a next generation particle accelerator. Still, there are some problems to solve for real applications. For example, it has been observed that the accelerated electron beam from laser and plasma based accelerators has a 100% energy spread. Thus, the generation of small energy spread beam is an important issue in the laser and plasma based accelerator study. In this work, we introduce a method to control the energy spread. From a basic theory and simulation, it is found that the transverse electron distribution is changed from the Gaussian to a Maxwell-Boltzmann distribution and low energy electrons spread out more rapidly than high energy electrons as they propagate in vacuum. Thus, a small size collimator is installed to remove the small energy electrons and it is conformed that the small energy spread can be obtained from an experiment.

 
 
TPAE010 Resonant Excitation of Selected Modes by a Train of Electron Bunches in a Rectangular Dielectric Wakefield Accelerator single-bunch, radiation, resonance, simulation 1174
 
  • I.N. Onishchenko, N. Onishchenko, G. Sotnikov
    NSC/KIPT, Kharkov
  • T.C. Marshall
    Yale University, Physics Department, New Haven, CT
  Funding: This work was partly supported by CRDF award #UP2-2569-KH-04

The dielectric wake field accelerator is based on particle acceleration by wake fields excited in a dielectric waveguide by a regular sequence of electron bunches. Enhancement of the accelerating field can be achieved using two phenomena: coherent excitation by many bunches (multibunch effect) and constructive interference of many excited eigenmodes (multimode effect). It was believed that the latter is possible only for planar slab geometry in which the excited modes are equally spaced in frequency. By analysis and simulation, in this presentation the effect of wake field superposition to high amplitude is demonstrated for arbitrary rectangular geometry that is more realizable in experiment. We find this result using simultaneous multibunch and multimode operation providing the repetition frequency of the bunch sequence is equal to the frequency difference between selected modes, whereupon resonant oscillation takes place. Moreover, it is shown that for an appropriate choice of selected modes and bunch repetition frequency a "quasimonopolar” peaked wake field can be excited.

 
 
TPAE011 Fast Sweeping Device for Laser Bunch laser, radiation, acceleration, focusing 1219
 
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  Electro-optical laser sweeping device deflects the head and tail of laser bunch into different frontal directions, so at some distance, the laser bunch becomes tilted with respect to forward direction. For sweeping of laser bunch having 300 ps duration up to 10 mrad, the voltage drop along the laser bunch must be ~10kV. Repetition rate desirable for this type of device used in laser acceleration or generation of secondary back-scattered electrons is up to 1 MHz. Details of the scheme described here.  
 
TPAE014 Optical Phase Locking of Modelocked Lasers for Particle Accelerators laser, acceleration, vacuum, controls 1389
 
  • T. Plettner, S. Sinha, J. Wisdom
    Stanford University, Stanford, Califormia
  • E.R. Colby
    SLAC, Menlo Park, California
  Funding: Department of Energy DE-FG03-97ER41043, DARPA DAAD19-02-1-0184.

Particle accelerators require precise phase control of the electric field through the entire accelerator structure. Thus a future laser driven particle accelerator will require optical synchronism between the high-peak power laser sources that power the accelerator. The precise laser architecture for a laser driven particle accelerator is not determined yet, however it is clear that the ability to phase-lock independent modelocked oscillators will be of crucial importance. We report the present status on our work to demonstrate long term phaselocking between two modelocked lasers to within one dregee of optical phase and describe the optical synchronization techniques that we employ.

 
 
TPAE016 The Argonne Wakefield Accelerator Facility: Status and Recent Activities gun, laser, klystron, cathode 1485
 
  • M.E. Conde, S.P. Antipov, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, H. Wang, Z.M. Yusof
    ANL, Argonne, Illinois
  Funding: This work is supported by the U.S. Department of Energy, under contract No. W-31-109-ENG-38.

The Argonne Wakefield Accelerator Facility (AWA) is dedicated to the study of electron beam physics and the development of accelerating structures based on electron beam driven wakefields. In order to carry out these studies, the facility employs a photocathode RF gun capable of generating electron beams with high bunch charges (up to 100 nC) and short bunch lengths. This high intensity beam is used to excite wakefields in the structures under investigation. The wakefield structures presently under development are dielectric loaded cylindrical waveguides with operating frequencies of 7.8 or 15.6 GHz. The facility is also used to investigate the generation and propagation of high brightness electron beams. Presently under investigation, is the use of photons with energies lower than the work function of the cathode surface (Schottky-enabled photoemission), aimed at generating electron beams with low thermal emittance. Novel electron beam diagnostics are also developed and tested at the facility. The AWA electron beam is also used in laboratory-based astrophysics experiments; namely, measurements of microwave Cherenkov radiation and fluorescence of air. We report on the current status of the facility and present recent results.

 
 
TPAE024 Determination of Longitudinal Phase Space in SLAC Main Accelerator Beams simulation, plasma, acceleration, radiation 1856
 
  • C.D. Barnes, F.-J. Decker, P. Emma, M.J. Hogan, R.H. Iverson, P. Krejcik, C.L. O'Connell, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, D.K. Johnson, C. Joshi, W. Lu, K.A. Marsh
    UCLA, Los Angeles, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  In the E164 Experiment at that Stanford Linear Accelerator Center (SLAC), we seek to drive plasma wakes for electron acceleration using 28.5 GeV bunches from the main accelerator. These bunches can now be made with an RMS length of less than 20 microns, and direct measurement is not feasible. Instead, we use an indirect technique, measuring the energy spectrum at the end of the linac and comparing with detailed simulations of the entire machine. We simulate with LiTrack, a 2D code developed at SLAC which includes wakefields, synchrotron radiation and all second order optical aberrations. Understanding the longitudinal profile allows a better understanding of acceleration in the plasma wake, as well as investigation of possible destructive transverse effects. We present results from the July 2004 experimental run and show how this technique aids in data analysis. We also discuss accuracy and validation of phase space determinations.  
 
TPAE025 Field Ionization of Neutral Lithium Vapor using a 28.5 GeV Electron Beam plasma, acceleration, diagnostics, radiation 1904
 
  • C.L. O'Connell, C.D. Barnes, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, D.K. Johnson, C. Joshi, W. Lu, K.A. Marsh, W.B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  The E164/E164X plasma wakefield experiment studies beam-plasma interactions at the Stanford Linear Acceleration Center (SLAC). Due to SLAC recent ability to variably compress bunches longitudinally from 650 microns down to 20 microns, the incoming beam is sufficiently dense to field ionize the neutral Lithium vapor. The field ionization effects are characterized by the beam’s energy loss through the Lithium vapor column. Experimental results are presented.  
 
TPAE027 Calculations for Tera-Hertz (THz) Radiation Sources radiation, simulation, scattering, laser 1994
 
  • J.E. Spencer, Y.A. Hussein
    SLAC, Menlo Park, California
  Funding: This work was supported by the U.S. Department of Energy under contract DE-2-76SF00515.

We explore possibilities for THz sources from 0.3 - 30 THz. While still inaccessible, this broad gap is even wider for advanced acceleration schemes extending from X or, at most, W band RF at the low end up to CO2 lasers. While the physical implementations of these two approaches are quite different, both are proving difficult to develop so that even lower frequency, superconducting RF seems to be the currently preferred means. Similarly, the validity of modelling techniques varies greatly over this range of frequencies but generally mandates coupling Maxwell’s equations to the appropriate device transport physics for which there are many options. Here we calculate radiation from shaped transmission lines using finite-difference, time-domain (FDTD) simulations of Maxwell’s equations coupled to Monte-Carlo techniques for both the production and transport physics of short electron pulses. Examples of THz sources that demonstrate coherent interference effects will be discussed with the goal of optimizing on-chip THz radiators for different applications - ultimately including improved electron sources and accelerators.

 
 
TPAE029 High-Harmonic Inverse Free-Electron-Laser Interaction at 800 nm laser, simulation, undulator, resonance 2113
 
  • C.M.S. Sears, E.R. Colby, B.M. Cowan, R. Siemann, J.E. Spencer
    SLAC, Menlo Park, California
  • R.L. Byer, T. Plettner
    Stanford University, Stanford, Califormia
  Funding: This work supported by Department of Energy contracts DE-AC03-76SF00515 (SLAC) and DE-FG03-97ER41043-II (Stanford).

The inverse Free Electron Laser (IFEL) interaction has recently been proposed and used as a short wavelength modulator forμbunching of beams for laser acceleration experiments*,**. These experiments utilized the fundamental of the interaction between the laser field and electron bunch. In the current experiment, we explore the higher order resonances of the IFEL interaction from a 3 period, 1.8 centimeter wavelength undulator with a picosecond, 0.25 mJ/pulse laser at 800 nm. The resonances are observed by adjusting the gap of the undulator while keeping the beam energy constant. We will also discuss diagnostics for obtaining beam overlap and statistical techniques used to account for machine drifts and analyze the data.

*W. D. Kimura, et. al., Phys. Rev. S.T. Acc. & Beams 4 101301 (2001). ** P. Musumeci, et. al., AAC 2004 Proceedings. Pg 170.

 
 
TPAE030 Distributed Bragg Coupler for Optical All-Dielectric Electron Accelerator coupling, laser, vacuum, radiation 2125
 
  • Z. Zhang, R.D. Ruth, S.G. Tantawi
    SLAC, Menlo Park, California
  Funding: Department of Energy.

A Bragg waveguide consisting of multiple dielectric layers with alternating index of refraction becomes an excellent option to form electron accelerating structure powered by high power laser sources. It provides confinement of a synchronous speed-of-light mode with extremely low loss. However, laser field can not be coupled into the structure collinearly with the electron beam. There are three requirements in designing input coupler for a Bragg electron accelerator: side-coupling, selective mode excitation, and high coupling efficiency. We present a side coupling scheme using a Bragg-grating-assisted input coupler to inject the laser into the waveguide. Side coupling is achieved by a second order Bragg grating with a period on the order of an optical wavelength. The phase matching condition results in resonance coupling thus providing selective mode excitation capability. The coupling efficiency is limited by profile mismatch between the outgoing beam and the incoming beam, which has normally, a Gaussian profile. We demonstrate a non-uniform distributed grating structure generating an outgoing beam with a Gaussian profile, therefore, increasing the coupling efficiency.

 
 
TPAE032 Particle-in-Cell Simulations of Lower-Density CM-Scale Capillary Channels laser, plasma, simulation, vacuum 2248
 
  • P. Messmer, D.L. Bruhwiler, D.A. Dimitrov, P. Stoltz
    Tech-X, Boulder, Colorado
  • E. Esarey, C.G.R. Geddes, W. Leemans
    LBNL, Berkeley, California
  Funding: This work is funded by DOE under contracts DE-FC02-01ER41178, DE-FG02-04ER84097, DE-AC03-76SF00098 and DE-FG03-95ER40926, including the SciDAC Accelerator Project and use of NERSC.

Capillary channels of cm-length and at plasma density low compared to gas jets are promising setups for low noise laser wakefield acceleration. Computationally, however, the large discrepancy of the length scales of the plasma and the laser are a big challenge. Methods are therefore sought that relax the need to concurrently resolve both length scales. Moving windows allow to reduce the size of the computational box to a few plasma wave-lengths, which can already be a big gain compared to the full length of the capillary. On the other hand, average methods allow to relax the constraint to resolve the laser wavelength. These methods split the laser induced current into a fast varying part and a slowly varying envelope. The average over the fast timescales is performed in a semi analytic way, leaving the evolution of the envelope to be modeled. Such an envelope model is currently being incorporated into the VORPAL code.* Preliminary results show considerable time savings compared to fully resolved simulations. The status of this ongoing work will be presented.

*C. Nieter and J. R. Cary, J. Comp. Phys. 196 (2004), p. 448.

 
 
TPAE037 Simulation of the Laser Acceleration Experiment at the Femilab/NICADD Photoinjector Laboratory laser, acceleration, vacuum, interaction-region 2503
 
  • P. Piot
    Fermilab, Batavia, Illinois
  • A.C. Melissinos, R. Tikhoplav
    Rochester University, Rochester, New York
  The possibility of using a laser to accelerate electrons in a waveguide structure with dimension much larger than the laser wavelength was first proposed by Pantell [NIM A 393 pg 1-5 (1997)] and investigated analytically by M. Xie [reports LBNL-40558 (1997) and LBNL-42055 (1998) available from LBNL Berkeley]. In the present paper we present the status of our experimental plan to demonstrate the laser interaction on an electron beam with initial momentum of 40-50 MeV/c. A laser (λ=1.06 micron) operating on the TM*01 mode has been developed. The large wavenumber (k~6x106 m-1) together with the initial low electron momentum poses a serious problem for efficient acceleration. In the present paper, we present start-to-end simulations of the laser acceleration experiment as foreseen to be installed in the upgraded Femilab/NICADD photoinjector laboratory.  
 
TPAE039 The Effects of Ion Motion in Very Intense Beam-Driven Plasma Wakefield Accelerators ion, plasma, emittance, collider 2562
 
  • J.B. Rosenzweig, A.M. Cook, M.C. Thompson, R.B. Yoder
    UCLA, Los Angeles, California
  Funding: This work is supported by U.S. Dept. of Energy grant DE-FG03-92ER40693.

Recent proposals for using plasma wakefield accelerators in the blowout regime as a component of a linear collider have included very intense driver and accelerating beams, which have densities many times in excess of the ambient plasma density. The electric fields of these beams are widely known to be large enough to completely expel plasma electrons from the beam path; the expelled electrons often attain relativistic velocities in the process. We examine here another aspect of this high-beam density scenario: the motion of ions. In the lowest order analysis, for both cylindrically symmetric and "flat" beams, it is seen that for the recently discussed "after-burner" scenario the ions completely collapse inside of the electron beam. In this case the ion density is significantly increased, with a large increase in the beam emittance expected as a result. Particle-in-cell simulations of ion-collapse in the nonlinear regime are discussed.

 
 
TPAE043 Production of Terahertz Seed Radiation for FEL/IFEL Microbunchers for Second Generation Plasma Beatwave Experiments at Neptune radiation, laser, plasma, beat-wave 2780
 
  • J.E. Ralph, C. Joshi, J.B. Rosenzweig, C. Sung, S. Tochitsky
    UCLA, Los Angeles, California
  Funding: This work was supported by the DOE Contract No. DE-FG03-92ER40727.

To achieve phase locked injection of short electron bunches in a plasma beatwave accelerator, the Neptune Laboratory will utilize microbunching in an FEL or IFEL system. These systems require terahertz (THz) seed radiation on the order of 10 kW for the FEL and 10 MW for the IFEL bunchers. We report results of experiments on THz generation using nonlinear frequency mixing of CO2 laser lines in GaAs. A two-wavelength laser beam was split and sent onto a 2.5 cm long GaAs crystal cut for noncollinear phase matching. Low power measurements achieved ~1 W of 340 ?m radiation using 200 ns CO2 pump pulses with wavelengths 10.3?m and 10.6?m. We also demonstrated tunability of difference frequency radiation, producing 240?m by mixing two different CO2 laser lines. By going to shorter laser pulses and higher intensities, we were able to increase the conversion efficiency while decreasing the surface damage threshold. Using 200ps pulses we produced ~2 MW of 340 ?m radiation. Future studies in this area will focus on developing large diameter Quasi-Phase matched structures for production of high power THz radiation.

 
 
TPAE044 Terahertz IFEL/FEL Microbunching for Plasma Beatwave Accelerators undulator, radiation, plasma, laser 2812
 
  • C. Sung, C.E. Clayton, C. Joshi, P. Musumeci, C. Pellegrini, J.E. Ralph, S. Reiche, J.B. Rosenzweig, S. Tochitsky
    UCLA, Los Angeles, California
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-FG03-92ER40727.

In order to obtain monoenergetic acceleration of electrons, phase-locked injection using electron microbunches shorter than the accelerating structure is necessary. For a laser-driven plasma beatwave accelerator experiment, we propose to microbunch the electrons by interaction with terahertz (THz) radiation in an undulator via two mechanisms– free electron laser (FEL) and inverse free electron laser (IFEL). Since the high power FIR radiation will be generated via difference frequency mixing in GaAs by the same CO2 beatwave used to drive the plasma wave, electrons could be phase-locked and pre-bunched into a series of microbunches separated with the same periodicity. Here we examine the criteria for undulator design and present simulation results for both IFEL and FEL approaches. Using different CO2 laser lines, electrons can be microbunched with different periodicity 300 – 100 mm suitable for injection into plasma densities in the range 1016 – 1017 cm-3, respectively. The requirement on the THz radiation power and the electron beam qualities are also discussed.

 
 
TPAE046 Modeling Self-Ionized Plasma Wakefield Acceleration for Afterburner Parameters Using QuickPIC simulation, plasma, betatron, acceleration 2905
 
  • M. Zhou, C.E. Clayton, V.K. Decyk, C. Huang, D.K. Johnson, C. Joshi, W. Lu, W.B. Mori, F.S. Tsung
    UCLA, Los Angeles, California
  • F.-J. Decker, R.H. Iverson, C.L. O'Connell, D.R. Walz
    SLAC, Menlo Park, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  Funding: DOE

A plasma wakefield accelerator (PWFA) has been proposed as a way to double the energy of a future linear collider. This afterburner concept will require meter long uniform plasmas. For the parameters envisaged in possible afterburner stages, the self-fields of the particle beam are intense enough to tunnel ionize some neutral gases such as lithium. Tunnel ionization has been investigated as a way for the beam itself to create the plasma.* Furthermore, tunnel ionization in a neutral or partially pre-ionized gas may create new plasma electrons and alter the plasma wake.*,** Unfortunately, it is not possible to model a PWFA with afterburner parameters using the models described in Bruhwiler et al. and Deng et al. Here we describe the addition of a tunnel ionization package using the ADK model into QuickPIC, a highly efficient quasi-static particle in cell (PIC) code which can model a PWFA with afterburner parameters. There is excellent agreement between QuickPIC and OSIRIS(a full PIC code) for pre-ionized plasmas. Effects of self-ionization on hosing instability –one of the most critical issues to overcome to make an afterburner a reality – for a bunch propagating in a plasma hundreds of betatron oscillations long will be discussed.

*D. L. Bruhwiler et al., Phys. Plasmas 10 (2003), p. 2022. **S. Deng et al., Phys. Rev. E, 68, 047401 (2003).

 
 
TPAE047 Parameters Optimization for a Novel Vacuum Laser Acceleration Test at BNL-ATF laser, acceleration, vacuum, simulation 2959
 
  • L.H. Shao, D. Cline, F. Zhou
    UCLA, Los Angeles, California
  Funding: U.S. DOE.

This paper presents a new VLA theory model which has revealed that the injection electrons with low energy and small incident angle relative to the laser beam are captured and significantly accelerated in a strong laser field. For the further step for verifying the novel-VLA mechanics, we propose to use the BNL-ATF Terawatt CO2 laser and a high-brightness electron beam to carry out a proof-of-principle beam experiment. Experiment setup including the laser injection optics and electron extraction system and beam diagnostics is presented. Extensive optimized simulation results with ATF practical parameters are also presented, which shows that even when the laser intensity is not very high, the net energy gain still can be seen obviously. This could be prospect for a new revolution of vacuum laser acceleration.

 
 
TPAE048 The UCLA/FNPL Time Resolved Underdense Plasma Lens Experiment plasma, focusing, quadrupole, space-charge 3013
 
  • M.C. Thompson, H. Badakov, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • H. Edwards, R.P. Fliller, G.M. Kazakevich, P. Piot, J.K. Santucci
    Fermilab, Batavia, Illinois
  • J.L. Li, R. Tikhoplav
    Rochester University, Rochester, New York
  Funding: Work Supported by U.S. Dept. of Energy grant DE-FG03-92ER40693.

An underdense plasma lens experiment is planned as a collaboration between UCLA and the Fermilab NICADD Photoinjector Laboratory (FNPL). The experiment will focus on measuring the variation of the plasma focusing along the longitudinal beam axis and comparing these results with theory and simulation. The experiment will utilize a thin gaussian underdense plasma lens with peak density 6 x 1012 cm-3 and a FWHM length of 1.6 cm. This plasma lens will have a focusing strength equivalent to a quadrupole magnet with a 180 T/m field gradient. A 15 MeV, 8nC electron beam with nominal dimensions sr = 400 μm and sz = 2.1 mm will be focused by this plasma lens onto an OTR screen approximately 2 cm downstream of the lens. The light from the OTR screen will be imaged into a streak camera in order to directly measure the correlation between z and sr within the beam. Status and progress on the experiment are reported.

 
 
TPAE049 The UCLA/SLAC Ultra-High Gradient Cerenkov Wakefield Accelerator Experiment radiation, simulation, laser, photon 3067
 
  • M.C. Thompson, H. Badakov, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • M.J. Hogan, R. Ischebeck, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • P. Muggli
    USC, Los Angeles, California
  • A. Scott
    UCSB, Santa Barbara, California
  • R.B. Yoder
    ,
  Funding: Work Supported by U.S. Dept. of Energy grant DE-FG03-92ER40693.

An experiment is planned to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range. This new UCLA/SLAC collaboration will take advantage of the unique SLAC FFTB electron beam and its demonstrated ultra-short pulse lengths and high currents (e.g., sz = 20 μm at Q = 3 nC). The electron beam will be focused down and sent through varying lengths of fused silica capillary tubing with two different sizes: ID = 200 μm / OD = 325 μm and ID = 100 μm / OD = 325 μm. The pulse length of the electron beam will be varied in order to alter the accelerating gradient and probe the breakdown threshold of the dielectric structures. In addition to breakdown studies, we plan to collect and measure coherent Cerenkov radiation emitted from the capillary tube to gain information about the strength of the accelerating fields. Status and progress on the experiment are reported.

 
 
TPAE051 Designing Photonic Crystal Devices for Accelerators lattice, coupling, simulation, photon 3164
 
  • G.R. Werner
    CIPS, Boulder, Colorado
  • J.R. Cary
    Tech-X, Boulder, Colorado
  Funding: This work supported by U.S. Department of Energy grant DE-FG02-04ER41317.

Photonic crystals (periodic dielectric structures with a lattice constant on the order of the wavelength of light) can have a wide range of properties. For instance, photonic crystals can be designed to be completely reflective within a certain bandwidth, thereby becoming a replacement for metal in accelerator structures such as waveguides and cavities. To see whether photonic crystals might find application in accelerators, and to design potential accelerator structures, we will need reliable computer simulations to predict fields and frequencies and other properties of photonic crystal structures. We propose to build photonic crystal structures in the microwave regime and test the validity of computer simulation against experiment. We can then explore more complex issues such as coupling to photonic crystal structures, higher-order mode rejection, and tunable photonic crystals.

 
 
TPAE053 Near-GeV Electron Beams from the Laser Wakefield Accelerator in the “Bubble” Regime laser, plasma, simulation, vacuum
 
  • N. Hafz, H. Suk
    KERI, Changwon
  • D.-K. Ko, J. Lee
    APRI-GIST, Gwangju
  Funding: This research was funded by the Korean Ministry Science and Technology through the Creative Research Initiative (CRI) Program.

This Communication describes a 2D-PIC simulation of a laser wakefield accelerator in which an ultrashort, petawatt-class laser is focused and propagated through an underdense preformed plasma. We are looking at the phase-spaces of a large number of background plasma electrons that are accelerated to very high energies by the laser-induced plasma bubble. The result shows the possibility of generating a GeV-level electron beam in a few millimeters plasma size. As a future work, we will use a 500 TW laser system, that is under construction at APRI-GIST in Korea, for laser-plasma based accelerator researches to which the current simulation is relevant.

 
 
TPAE054 Ultraintense and Ultrashort Laser Pulses from Raman Amplification in Plasma for Laser-Plasma Accelerators simulation, plasma, laser, resonance 3274
 
  • M.S. Hur, G.-H. Kim, H. Suk
    KERI, Changwon
  • A.E. Charman, R.R. Lindberg, J.S. Wurtele
    LBNL, Berkeley, California
  Funding: Korea Electrotechnology Research Institute, Korea; Creative Research Initiatives, Korea.

We present analysis and simulations of kinetic effects in the Raman pulse amplification in plasma. An ultraintense and ultrashort laser pulse is a very essential part in an advanced acceleration scheme using laser and plasma. To make strong pulses, a noble scheme of using Raman backscatter in plasma was proposed and has been studied intensively.* The Raman amplification in plasma does not have a restriction in material damage threshold. However, for the new amplifier to be a promising alternative of the CPA technique, more extensive studies on various issues are required. One of the fundamental issues is the electron kinetic effect such as particle trapping or wavebreaking. We present a theoretical analysis of the kinetic effect; a new kinetic term is derived to be added to the fluid model and the effect of the new term is verified by averaged-PIC (aPIC)** simulations. Various one dimensional and semi-two dimensional aPIC simulations of pulse amplification are presented. We discuss the future application of the Raman scheme to upgrading the laser pulse of the Center of Advanced Accelerator in KERI, which are currently 2 TW and 700 fs, into a few more TW and less than 100 fs.

*V. M. Malkin, G. Shvets, and N. J. Fisch, Phys. Rev. Lett. vol. 82, 4448 (1999).**M. S. Hur, G. Penn, J. S. Wurtele, and R. Lindberg, Phys. Plasmas vol. 11, 5204 (2004).

 
 
TPAE056 Acceleration of Charged Particles by High Intensity Few-Cycle Laser Pulses laser, acceleration, plasma, undulator 3337
 
  • U. Schramm, F. Gruener, D. Habs, J. Schreiber
    LMU, München
  • S. Becker, M. Geissler, S. Karsch, F. Krausz, J. Meyer-ter-Vehn, K. Schmid, G. Tsakiris, L. Veisz, K. Witte
    MPQ, Garching, Munich
  Funding: Funded by the german DFG (TR18) and BMBF (06ML184).

Only recently a breakthrough in laser plasma acceleration has been achieved with the observation of intense (nC) mono-energetic (10% relative width) electron beams in the 100MeV energy range.* Above the wave-breaking threshold the electrons are trapped and accelerated in a single wake of the laser pulse, called bubble, according to PIC simulations.** However, pulse energis varied from shot-to-shot in the experiments. At the MPQ Garching we prepare the stable acceleration of electrons by this bubble regime by the use of 10TW few-cycle laser pulse. As the pulse lenght of 5-10fs remains below the plasma period also at higher plama densities, we expect the scheme to be more stable and efficient. The status of the experiment will be reported. Further, we exploit a colliding beam setup existing at the Jena multi TW laser system for the investigation of the positron generation in the electron-electron collision or in the collision of hard X-rays resulting from Thomson backscattering. The presentation of results on heavy ion acceleration from laser-irradiated thin foils will round up this summary of the Munich activities.

*See ‘dream beams' in Nature 431 (2004).**A. Pukhov, J. Meyer-ter-Vehn, Appl. Phys. B 74, 355 (2002).

 
 
TPAE057 A Multibunch Plasma Wakefield Accelerator plasma, laser, simulation, background 3384
 
  • E.K. Kallos, T.C. Katsouleas, P. Muggli
    USC, Los Angeles, California
  • M. Babzien, I. Ben-Zvi, K. Kusche, P.I. Pavlishin, I. Pogorelsky, V. Yakimenko
    BNL, Upton, Long Island, New York
  • W.D. Kimura
    STI, Washington
  • F. Zhou
    UCLA, Los Angeles, California
  We investigate a plasma wakefield acceleration scheme where a train of electron microbunches feeds into a high density plasma. When the microbunch train enters such a plasma that has a corresponding plasma wavelength equal to the microbunch separation distance, a strong wakefield is expected to be resonantly driven to an amplitude that is at least one order of magnitude higher than that using an unbunched beam. PIC simulations have been performed using the beamline parameters of the Brookhaven National Laboratory Accelerator Test Facility operating in the configuration of the STELLA inverse free electron laser (IFEL) experiment. A 65 MeV electron beam is modulated by a 10.6 um CO2 laser beam via an IFEL interaction. This produces a train of ~90 microbunches separated by the laser wavelength. In this paper, we present both a simple theoretical treatment and simulation results that demonstrate promising results for the multibunch technique as a plasma-based accelerator.  
 
TPAE058 Plasma Dark Current in Self-ionized Plasma Wake Field Accelerators (PWFA) plasma, radiation, diagnostics, space-charge 3444
 
  • E. Oz, S. Deng, T.C. Katsouleas, P. Muggli
    USC, Los Angeles, California
  • C.D. Barnes, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, C.L. O'Connell, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, D.K. Johnson, C. Joshi, W. Lu, K.A. Marsh, W.B. Mori, M. Zhou
    UCLA, Los Angeles, California
  Particle trapping is investigated with experiment, theory and simulations for conditions relevant to beam driven Plasma Wake Field Accelerators. Such trapping produces plasma dark current when the wakefield aplitude is above a threshold values and may place a limit on the maximum acceleration gradient in a PWFA. Trapping and dark current are enhanced when in an ionizing plasma, that is self-ionized by the beam as well as in gradual density gradients. In the E164X conducted at the Stanford Linear Accelerator Center by a collaboration of USC, UCLA and SLAC, evidence of trapping has been observed. Here we present experimental results and a simplified analytical model of the particle trapping threshold which is compared to simulations done with an object oriented fully parallel 3-D PIC code OSIRIS.  
 
TPAE060 Planned Enhanced Wakefield Transformer Ratio Experiment at Argonne Wakefield Accelerator laser, simulation, linac, pick-up 3487
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • P.A. Avrakhov
    LPI, Moscow
  • W. Gai, C.-J. Jing, R. Konecny, J.G. Power
    ANL, Argonne, Illinois
  Funding: U.S. Department of Energy.

In this paper, we present a preliminary experimental study of a wakefield accelerating scheme that uses a carefully spaced and current ramped electron pulse train to produce wakefields that increases the transformer ratio much higher than 2. A dielectric structure was designed and fabricated to operate at 13.625 GHz with dielectric constant of 15.7. The structure will be initially excited by two beams with first and second beam charge ratio of 1:3. The expected transformer ratio is 3 and the setup can be easily extend to 4 pulses which leads to a transformer ratio of more than 6. The dielectric structure cold test results show the tube is within the specification. A set of laser splitters was also tested to produce ramped bunch train of 2 - 4 pulses. Overall design of the experiment and initial results will be presented.

 
 
TPAE061 Experimental Investigation of an X-Band Tunable Dielectric Accelerating Structure resonance, vacuum, acceleration, polarization 3529
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • W. Gai, J.G. Power
    ANL, Argonne, Illinois
  • S.F. Karmanenko, A. Semenov
    Eltech University, St. Petersburg
  • E. Nenasheva
    Ceramics Ltd., St. Petersburg
  • P. Schoessow
    Tech-X, Boulder, Colorado
  Funding: U.S. Department of Energy.

Experimental study of a new scheme to tune the resonant frequency for dielectric based accelerating structure (driven either by the wakefield of a beam or an external rf source) is underway. The structure consists of a single layer of conventional dielectric surrounded by a very thin layer of ferroelectric material situated on the outside. Carefully designed electrodes are attached to a thin layer of ferroelectric material. A DC bias can be applied to the electrodes to change the permittivity of the ferroelectric layer and therefore, the dielectric overall resonant frequency can be tuned. In this paper, we present the test results for an 11.424 GHz rectangular DLA prototype structure that the ferroelectric material's dielectric constant of 500 and show that a frequency tuning range of 2% can be achieved. If successful, this scheme would compensate for structure errors caused by ceramic waveguide machining tolerances and dielectric constant heterogeneity.

 
 
TPAE063 Observation of Superposition of Wake Fields Generated by Electron Bunches in a Dielectric-Lined Waveguide acceleration, gun, vacuum, laser 3609
 
  • S.V. Shchelkunov, T.C. Marshall
    Columbia University, New York
  • M. Babzien
    BNL, Upton, Long Island, New York
  • J.L. Hirshfield, M.A. LaPointe
    Yale University, Physics Department, New Haven, CT
  Funding: Research supported by the Department of Energy, Division of High Energy Physics.

We report results from an experiment, done at the Accelerator Test Facility, Brookhaven National Laboratory, which demonstrates the successful superposition of wake fields excited by 50MeV bunches which travel ~50cm along the axis of a cylindrical waveguide which is lined with alumina. Wake fields from two short (5-6psec) 0.15-0.35nC bunches are superimposed and the energy losses of each bunch are measured as the separation between the bunches is varied so as to encompass approximately one wake field period (~21cm). A spectrum of 40 TM0m eigenmodes is excited by the bunch. A substantial retarding wake field (2.65MV/m×nC for just the first bunch) is developed because of the short bunches and the narrow vacuum channel diameter (3mm) through which they move. The energy loss of the second bunch exhibits a narrow resonance with a 4mm (13.5psec) footprint. This experiment may be compared with a related experiment reported by a group at the Argonne National Laboratory where a much weaker wake field (~0.1MV/m×nC for the first bunch) having ~10 eigenmodes was excited by a train of much longer bunches,* and the bunch spacing was not varied.

*J. G. Power, M. E. Conde, W. Gai, R. Konecny, and P. Schoessow, Phys. Rev. ST Accel. Beams 3, 101302 (2000).

 
 
TPAE064 Externally Controlled Injection of Electrons by a Laser Pulse in a Laser Wakefield Electron Accelerator injection, plasma, laser, scattering 3644
 
  • S.-Y. Chen, C.-L. Chang, W.-T. Chen, T.-Y. Chien, C.-H. Lee, J.-Y. Lin, J. Wang
    IAMS, Taipei
  Funding: National Science Council, Taiwan

Spatially and temporally localized injection of electrons is a key element for development of plasma-wave electron accelerator. Here we report the demonstration of two different schemes for electron injection in a self-modulated laser wakefield accelerator (SM-LWFA) by using a laser pulse. In the first scheme, by implementing a copropagating laser prepulse with proper timing, we are able to control the growth of Raman forward scattering and the production of accelerated electrons. We found that the stimulated Raman backward scattering of the prepulse plays the essential role of injecting hot electrons into the fast plasma wave driven by the pump pulse. In the second scheme, by using a transient density ramp we achieve self-injection of electrons in a SM-LWFA with spatial localization. The transient density ramp is produced by a prepulse propagating transversely to drill a density depression channel via ionization and expansion. The same mechanism of injection with comparable efficiency is also demonstrated with a transverse plasma waveguide driven by Coulomb explosion.

 
 
TPAE065 Development of a 20-MeV Dielectric-Loaded Accelerator Test Facility shielding, injection, acceleration, controls 3673
 
  • S.H. Gold
    NRL, Washington, DC
  • H. Chen, Y. Hu, Y. Lin, C. Tang
    TUB, Beijing
  • W. Gai, C.-J. Jing, R. Konecny, J.G. Power
    ANL, Argonne, Illinois
  • A.K. Kinkead
    ,
  • C.D. Nantista, S.G. Tantawi
    SLAC, Menlo Park, California
  Funding: Work supported by DOE and ONR.

This paper will describe a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded accelerator (DLA) test facility powered by the high-power 11.424-GHz magnicon that was developed by NRL and Omega-P, Inc. The magnicon can presently produce 25 MW of output power in a 250-ns pulse at 10 Hz, and efforts are in progress to increase this to 50 MW.* The facility will include a 5-MeV electron injector being developed by the Accelerator Laboratory of Tsinghua University in Beijing, China. The DLA test structures are being developed by ANL, and some have undergone testing at NRL at gradients up to ~8 MV/m.** SLAC is developing a means to combine the two magnicon output arms, and to drive an injector and accelerator with separate control of the power ratio and relative phase. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA structure, and spectrometer, should take place within the next year. The initial goal is to produce a compact 20-MeV dielectric-loaded test accelerator.

*O. A. Nezhevenko et al., Proc. PAC 2003, p. 1128.**S. H. Gold et al., AIP Conf. Proc. 691, p. 282.

 
 
TPAE066 Robust Autoresonant Excitation in the Plasma Beat-Wave Accelerator: A Theoretical Study plasma, laser, resonance, beat-wave 3688
 
  • A.E. Charman, R.R. Lindberg, J.S. Wurtele
    UCB, Berkeley, California
  • L. Friedland
    The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem
  Funding: Division of High Energy Physics, U.S. Department of Energy, DARPA, U.S. Department of Defense.

A modified version of the Plasma Beat-Wave Accelerator scheme is introduced and analyzed, which is based on autoresonant phase-locking of the nonlinear Langmuir wave to the slowly chirped beat frequency of the driving lasers via adiabatic passage through resonance. This new scheme is designed to overcome some of the limitations of previous approaches, namely relativistic detuning and nonlinear modulations in the driven Langmuir wave amplitude, and sensitivity to frequency mismatch from density fluctuations. As in previous schemes, instabilities of the ionic background ultimately limit the useful interaction time, but nevertheless peak electric fields approaching the wave-breaking limit seem readily attainable. Compared to traditional approaches, the autoresonant scheme achieves larger accelerating electric fields for given laser intensity; the plasma wave excitation is more robust to variations in plasma density; it is largely insensitive to the choice of chirp rate, provided that chirping is sufficiently slow; and the quality and uniformity of the resulting plasma wave and its suitability for accelerator applications may be superior.

 
 
TPAE067 Femtosecond Electron Diffraction and its Application for Beam Characterization at the PAL laser, gun, emittance, space-charge 3721
 
  • D. Xiang
    TUB, Beijing
  • H. Ihee
    KAIST, Daejeon
  • I.S. Ko, S.J. Park
    PAL, Pohang, Kyungbuk
  • X.J. Wang
    BNL, Upton, Long Island, New York
  Electron diffraction is widely used in electron microscopy to obtain ultrahigh magnification factor, or crystallography to determine the internal structure of the molecule. High energy electron (MeV) has been used to probe the solid state thick sample, now being explored for femto-second electron diffraction (FED) to determine the transient structure of the molecule. We are proposing to perform FED using a photocathode RF gun at the Pohang Accelerator Laboratory (PAL), and develop an advanced electron beam diagnostic tool based on the electron diffraction. In this paper we will study how the diffraction pattern can be used to extract the information on the beam’s divergence. With a well-known sample, such as aluminum foil, whose internal structure is predetermined, the diffraction pattern for both single electron and the electron beam with a given divergence distribution can be calculated. Our proposed technique shows great potential of electron diffraction in beam divergence characterization. An experiment to verify the practicality of this method is under preparation and will be carried out at the proposed high brightness R&D facility at the PAL) in the near future.  
 
TPAP002 Summary of Recent Studies of Cryosorbers for LHC Long Straight Sections vacuum, collider, injection, hadron 791
 
  • R.V. Dostovalov, V.V. Anashin, A.A. Krasnov
    BINP SB RAS, Novosibirsk
  Funding: This work was supported by CERN AT Division vacuum group.

The vacuum chamber inside some cryogenic elements in the LHC long straight sections will have cold bore (CB) at 4.5K and a beam screen (BS) at temperature between 5 and 20K. The gas molecules desorbed due to photons and electrons will pass through the slots on the BS to the shadowed part between the CB and BS. All desorbed gases except H2 could be adsorbed on the CB and BS but a cryosorber is required to pump H2. The new types of anodized aluminum, porous copper and charcoal-based materials were developed and studied to cryopump H2 at temperatures between 10 and 20K. The advantages and disadvantages of cryosorbers and technological problems of development of new similar cryosorbers were defined. The vacuum parameters of LHC vacuum chamber prototypes with charcoal and two types of carbon fiber cryosorbers were measured. The dynamic pressure behavior at BS temperature oscillations was studied for BS with woven carbon fiber to predict the dynamic pressure at nonstandard or transient regimes of the LHC operation. A main result is that woven carbon fiber cryosorber meets the LHC requirements and can be proposed as cryosorber for LHC. The summary results of these studies are presented.

 
 
TPAP037 Monte Carlo of Tevatron Operations, Including the Recycler antiproton, luminosity, proton, emittance 2479
 
  • E.S. McCrory
    Fermilab, Batavia, Illinois
  Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

A Monte Carlo model, which was originally developed for "Run I" of the Tevatron Collider, has been enhanced in many ways, most notably, to incorporate the effect of the Recycler Ring. This model takes into account reasonable random fluctuations in the performance of the Collider, and normal interruptions in operation of each accelerator due to downtime. Optimization of the integrated luminosity delivered to the experiments is based on when to end the store and how to deal with the anitprotons. Preliminary results show that a 20% gain in integrated luminosity in the Collider results from using the Recycler for one-third of the anitprotons in each store. As electron cooling becomes operative in the Recycler, Collider performance improves by as much as a factor of two.

 
 
TPAP043 Electron Cooling of RHIC ion, emittance, linac, simulation 2741
 
  • I. Ben-Zvi, D.S. Barton, D.B. Beavis, M. Blaskiewicz, J.M. Brennan, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, R. Connolly, Yu.I. Eidelman, A.V. Fedotov, W. Fischer, D.M. Gassner, H. Hahn, M. Harrison, A. Hershcovitch, H.-C. Hseuh, A.K. Jain, P.D.J. Johnson, D. Kayran, J. Kewisch, R.F. Lambiase, V. Litvinenko, W.W. MacKay, G.J. Mahler, N. Malitsky, G.T. McIntyre, W. Meng, K.A.M. Mirabella, C. Montag, T.C.N. Nehring, T. Nicoletti, B. Oerter, G. Parzen, D. Pate, J. Rank, T. Rao, T. Roser, T. Russo, J. Scaduto, K. Smith, D. Trbojevic, G. Wang, J. Wei, N.W.W. Williams, K.-C. Wu, V. Yakimenko, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • D.T. Abell, D.L. Bruhwiler
    Tech-X, Boulder, Colorado
  • H. Bluem, A. Burger, M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • A.V. Burov, S. Nagaitsev
    Fermilab, Batavia, Illinois
  • J.R. Delayen, Y.S. Derbenev, L. W. Funk, P. Kneisel, L. Merminga, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
  • I. Koop, V.V. Parkhomchuk, Y.M. Shatunov, A.N. Skrinsky
    BINP SB RAS, Novosibirsk
  • I.N. Meshkov, A.O. Sidorin, A.V. Smirnov, G.V. Troubnikov
    JINR, Dubna, Moscow Region
  • J.S. Sekutowicz
    DESY, Hamburg
  We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.

Under contract with the U.S. Department of Energy, Contract Number DE-AC02-98CH10886.

 
 
TPAP047 Killing the Electron Cloud Effect in the LHC Arcs dipole, vacuum, proton, emittance 2971
 
  • P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, Texas
  A getter/electrode assembly has been devised to suppress the regeneration mechanism of the electron cloud effect in the arc dipoles of LHC. The assembly consists of a copper foil electrode, supported through an insulating layer on a stainless steel skid, which would rest upon the flat bottom of the beam screen. The electrode is coated with NEG to provide effective pumping of all non-inert gases from the vacuum. Pumping should be enhanced by electron bombardment. By biasing the electrode ~+100 V secondary electrons produced on the surface would be fully re-absorbed, killing the regeneration mechanism. The NEG surface can be regenerated by passing a current through the electrode to heat it to ~240 C. The heat transfer (radiant + conductive) to the beam screen during regeneration is estimated ~10 W/m, within limits to maintain the beam screen at nominal 20 K temperature during regeneration. The entire assembly has been designed so that installation does not require modification of any hardware currently being built for the LHC arcs. The electrode assembly would occupy 1 mm in the vertical aperture of the beam screen.  
 
TPAP056 Electron Beam Stability Requirements for Linac-Ring Electron-Ion Colliders simulation, ion, emittance, luminosity 3363
 
  • C. Montag
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

In recent years, linac-ring electron-ion colliders have been proposed at a number of laboratories around the world. While the linac-ring approach overcomes the beam-beam tuneshift limitation on the electron beam, it also introduces noise into the ion beam, via the beam-beam interaction with electron bunches of slightly fluctuating intensity and transverse size. The effect of these fluctuations is studied using a linearized model of the beam-beam interaction. Upper limits for the rms jitter amplitudes of electron beam parameters for various linac-ring electron-ion colliders are presented.

 
 
TPAP057 Beam-Beam Simulations for the eRHIC Electron Ring luminosity, simulation, resonance, emittance 3399
 
  • C. Montag
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

To study collisions between polarized electrons and heavy ions or polarized protons at high energy, adding a 10 GeV electron storage ring to the existing RHIC facility is currently under consideration. To achieve high luminosities, vertical beam-beam tuneshift parameters of 0.08 are required for the electron beam. Simulation studies are being performed to study the feasibility of these high tuneshift parameters and to explore the potential for even higher tuneshifts. Recent results of these studies are presented.

 
 
TPAP058 Beam-Beam Simulations for Double-Gaussian Beams emittance, simulation, luminosity, proton 3405
 
  • C. Montag, I. Ben-Zvi, V. Litvinenko, N. Malitsky
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two Gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-Gaussian beams. Here we report the effect of low-frequency random tune modulations on diffusion in double-Gaussian beams and compare the effects to those in beam-beam interactions with regular Gaussian beams and identical tuneshift parameters.

 
 
TPAT001 An Ultra-Bright Pulsed Electron Beam with Low Longitudinal Emittance laser, brightness, emittance, ion 770
 
  • M.S. Zolotorev, E. D. Commins, P. Denes, Z. Hussain, G.V. Lebedev, S.M. Lidia, D. Robin, F. Sannibale, R.W. Schoenlein, R. A. Vogel, W. Wan
    LBNL, Berkeley, California
  • S.A. Heifets
    SLAC, Menlo Park, California
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

We describe a novel scheme for an electron source in the 10 - 100 eV range with the capability of approaching the brightness quantum-limit and of lowering the effective temperature of the electrons orders of magnitude with respect to existing sources. Such a device can open the way for a wide range of novel applications that utilize angstrom-scale spatial resolution and ?eV-scale energy resolution. Possible examples include electron microscopy, electron holography, and investigations of dynamics on a picosecond time scale using pump-probe techniques. In this paper we describe the concepts for such a source including a complete and consistent set of parameters for the construction of a real device based on the presented scheme.

 
 
TPAT004 Strongly Asymmetric Beams at the University of Maryland Electron Ring (UMER) focusing, quadrupole, diagnostics, emittance 892
 
  • S. Bernal, R.A. Kishek, P.G. O'Shea, B. Quinn, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by U.S. Dept. of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

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

 
 
TPAT008 Numerical Dispersion Error Reduction in EM Calculations for Accelerators simulation, electromagnetic-fields, single-bunch, linac 1114
 
  • T. Lau, E. Gjonaj, T. Weiland
    TEMF, Darmstadt
  • I. Zagorodnov
    DESY, Hamburg
  Funding: Deutsches Elektronen-Synchrotron DESY

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

 
 
TPAT010 Practical Definitions of Beam Lifetimes in an Electron Storage Ring polarization, scattering, storage-ring, beam-losses 1216
 
  • T.-Y. Lee
    PAL, Pohang, Kyungbuk
  Derived are simple definitions of beam lifetimes in an electron storage ring. They are defined in terms of measured beam lifetime and its time derivative. They are practical rather than theoretical. The only condition required is suppression or saturation of the radiative polarization.  
 
TPAT023 Tests of a 3D Self Magnetic Field Solver in the Finite Element Gun Code MICHELLE gun, simulation, beam-transport, accumulation 1814
 
  • E.M. Nelson
    LANL, Los Alamos, New Mexico
  • J.J. Petillo
    SAIC, Burlington, Massachusetts
  Funding: Work supported by ONR.

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

 
 
TPAT033 Experimental Characterizations of 4-D Transverse Phase-Space of a Compressed Beam emittance, linac, space-charge, focusing 2263
 
  • F. Zhou, R.B. Agustsson, G. Andonian, D. Cline, A.Y. Murokh, J.B. Rosenzweig
    UCLA, Los Angeles, California
  • I. Ben-Zvi, V. Yakimenko
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. DOE.

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

 
 
TPAT034 Manipulations of Double Electron Beams within One RF Period for Seeded SM-LWFA Experiment laser, emittance, plasma, linac 2312
 
  • F. Zhou, D. Cline
    UCLA, Los Angeles, California
  • M. Babzien, V. Yakimenko
    BNL, Upton, Long Island, New York
  • W.D. Kimura
    STI, Washington
  Funding: Work supported by U.S. DOE.

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

 
 
TPAT035 Coherent Synchrotron Radiation from an Electron Beam in a Curved Waveguide radiation, emittance, simulation, synchrotron 2390
 
  • D.R. Gillingham, T. M. Antonsen, P.G. O'Shea
    IREAP, College Park, Maryland
  Funding: Research supported by the office of Naval Research and the Joint Technology Office.

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

 
 
TPAT036 Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization plasma, ion, heavy-ion, focusing 2452
 
  • P. Efthimion, R.C. Davidson, E.P. Gilson, L. Grisham
    PPPL, Princeton, New Jersey
  • B. G. Logan, W. Waldron, S. Yu
    LBNL, Berkeley, California
  Funding: Research supported by the U.S. Department of Energy.

Plasmas are employed as a medium for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ~ 0.1-1 m would be suitable. To produce 1 meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic. High voltage (~ 1-5 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long produced plasma densities ~ 5x1011 cm-3. The source was integrated into the experiment and successfully charge neutralized the K ion beam. Presently, the 1 meter source is being fabricated. It will be characterized and integrated into NDCX for charge neutralization experiments. Experimental results will be presented.

 
 
TPAT039 Wavelet-Based Poisson Solver for Use in Particle-in-Cell Simulations simulation, diagnostics, vacuum, plasma 2601
 
  • B. Terzic, C.L. Bohn, D. Mihalcea
    Northern Illinois University, DeKalb, Illinois
  • I.V. Pogorelov
    LBNL, Berkeley, California
  Funding: Work of B.T., D.M. and C.L.B. is supported by Air Force contract FA9471-040C-0199. Work of I.V.P. is supported by the U.S. Department of Energy contract DE-AC03-76SF00098.

We report on a successful implementation of a wavelet-based Poisson solver for use in 3D particle-in-cell simulations. One new aspect of our algorithm is its ability to treat the general (inhomogeneous) Dirichlet boundary conditions. The solver harnesses advantages afforded by the wavelet formulation, such as sparsity of operators and data sets, existence of effective preconditioners, and the ability simultaneously to remove numerical noise and further compress relevant data sets. Having tested our method as a stand-alone solver on two model problems, we merged it into IMPACT-T to obtain a fully functional serial PIC code. We present and discuss preliminary results of application of the new code to the modelling of the Fermilab/NICADD and AES/JLab photoinjectors.

Corresponding author: B.T. (bterzic@nicadd.niu.edu)

 
 
TPAT040 Actual Stationary State for Plasma Lens plasma, ion, acceleration, heavy-ion 2619
 
  • V. Zadorozhny
    NASU/IOC, Kiev
  • A. Goncharov
    NSC/KIPT, Kharkov
  • Z.P. Parsa
    BNL, Upton, Long Island, New York
  The electrostatic plasma lens (PL) provides an attractive and unique tool for manipulating high-current heavy ion beams. The fundamental concept of the PL is based on the use of magnetically insulated electrons and equipotentialization of magnetic field lines. Rigorous application of PL is, however, limited. The reason is the estimation behaviour of electrons for complicated magnetic fields runs into severe difficults.We show that there are specific conditions that admit steady-state of a longitudinal motion, and consider a question of it stability. These results are needed to develop an optimized PL with minimal spherical aberation, in party by optimization of the magnetic field conficuration in the low-magnetic-field range.  
 
TPAT047 A Space Charge Compensation Study of Low Energy Hydrogen Ion Beams space-charge, ion, simulation, emittance 2947
 
  • A. BenIsmail, R. Duperrier, D. Uriot
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • N. Pichoff
    CEA/DAM, Bruyères-le-Châtel
  Funding: Work supported by the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395).

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. The complexity of high intensity beam dynamics in the low energy line is essentially due to the non-linear space charge effects. The PIC code CARTAGO* has been developed in order to simulate the beam transport at low energy including the temporal evolution effects of the space charge compensation. This paper relates the structure and the numerical methods of a 2D (r,z) new version of the code. The effects of the longitudinal space charge, the image charge and external 2D (r,z) magnetic field were included. The results of H+ and H- beam transports using solenoid lenses are discussed. Space charge compensation degrees are given for each studied cases.

*A. Ben Ismail et al., in Space Charge Compensation in Low Energy Proton Beams, proceeding of the International Linear Accelerator Conference, Lübeck, 2004.

 
 
TPAT051 Asymmetrical Spectrum Observed at the KEKB High Energy Electron Ring ion, vacuum, luminosity, feedback 3176
 
  • T. Ieiri, Y. Ohnishi, M. Tobiyama
    KEK, Ibaraki
  KEKB is a multi-bunch, high-current, electron/positron collider for B meson physics. The two beams collide at one interaction point (IP) with a finite horizontal crossing angle. The luminosity achieved at KEKB is the best in the world. In order to keep up the performance, the tune of a non-colliding bunch, placed just after a colliding bunch-train, is continuously monitored. It was observed that an electron bunch showed an asymmetrical distribution biased to a higher tune in the vertical tune-spectrum. We found that the asymmetrical spectrum was reinforced by the beam-beam interaction, though the electron bunch did not collide. The asymmetry was reinforced moreover, as the electron bunch approached a bunch-train further. These observations suggest that the asymmetry in the spectrum is not related to trapped-ions or fast-ions observed in an electron single beam, but related to ions produced by the beam-beam interaction, which makes the particles scattered and they might yield new ions due to the collision with residual gas. We can imagine that the ions are accumulated along a bunch-train and some ions survive after colliding bunches passed through in the electron ring. A quantitative analysis remains for future study.  
 
TPAT058 Calculation of Electron Beam Potential Energy from RF Photocathode Gun simulation, gun, space-charge, acceleration 3441
 
  • W. Liu
    Illinois Institute of Technology, Chicago, Illinois
  • W. Gai, J.G. Power, H. Wang
    ANL, Argonne, Illinois
  Funding: U.S. Department of Energy.

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

 
 
TPAT062 Uncorrelated Energy Spread and Longitudinal Emittance for a Photoinjector Beam space-charge, gun, emittance, simulation 3570
 
  • Z. Huang, D. Dowell, P. Emma, C. Limborg-Deprey, G.V. Stupakov, J. Wu
    SLAC, Menlo Park, California
  Longitudinal phase space properties of a photoinjector beam are important in many areas of high-brightness beam applications such as bunch compression, transverse-to-longitudinal emittance exchange, and high-gain free-electron lasers. In this paper, we discuss both the rf and the space charge contributions to the uncorrelated energy spread of the beam generated from a laser-driven rf gun. We compare analytical expressions for the uncorrelated energy spread and the longitudinal emittance with numerical simulations and recent experimental results.  
 
TPAT066 Significance of Space Charge and the Earth Magnetic Field on the Dispersive Characteristics of a Low Energy Electron Beam space-charge, emittance, simulation, lattice 3691
 
  • R.A. Kishek, G. Bai, S. Bernal, T.F. Godlove, I. Haber, P.G. O'Shea, B. Quinn, C. Tobin, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by U.S. Dept. of Energy grant numbers DE-FG02-94ER40855 and DE-FG02-92ER54178.

The combination of energy spread and space charge provides a rich domain for interesting beam dynamics that are currently not well understood. The University of Maryland Electron Ring (UMER) [1] is a small scaled ring designed to probe the little-known regions of higher beam intensities using low-energy electrons. As such, design, commissioning and operation of UMER present many challenges, some quite novel. For example the UMER beam energy of 10 keV makes the beam very sensitive to the Earth magnetic field, which we can fortunately use to assist in bending the beam. This paper presents a systematic simulation study of the interaction of space charge and energy spread, with and without the earth magnetic field.

*"Commissioning of the University of Maryland Electron Ring (UMER)," S. Bernal, et al., this conference.

 
 
TPAT067 Study of Longitudinal Space-Charge Wave Dynamics in Space-Charge Dominated Beams space-charge, simulation, gun, ion 3712
 
  • K. Tian, Y. Cui, I. Haber, Y. Huo, R.A. Kishek, P.G. O'Shea, Y. Zou
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: Work supported by the U.S. Department of Energy, Office of Science.

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

 
 
TPAT068 A Fast Faraday Cup for the Neutralized Drift Compression Experiment ion, plasma, simulation, target 3765
 
  • A.B. Sefkow, R.C. Davidson, P. Efthimion, E.P. Gilson
    PPPL, Princeton, New Jersey
  • F.M. Bieniosek, J.E. Coleman, S. Eylon, W.G. Greenway, E. Henestroza, J.W. Kwan, P.K. Roy, D.L. Vanecek, W. Waldron, S. Yu
    LBNL, Berkeley, California
  • D.R. Welch
    ATK-MR, Albuquerque, New Mexico
  Funding: Research supported by the U.S. Department of Energy.

Heavy ion drivers for high energy density physics applications and inertial fusion energy use space-charge-dominated beams which require longitudinal bunch compression in order to achieve sufficiently high beam intensity at the target. The Neutralized Drift Compression Experiment-1A (NDCX-1A) at Lawrence Berkeley National Laboratory (LBNL) is used to determine the effective limits of neutralized drift compression. NDCX-1A investigates the physics of longitudinal drift compression of an intense ion beam, achieved by imposing an initial velocity tilt on the drifting beam and neutralizing the beam's space-charge with background plasma. Accurately measuring the longitudinal compression of the beam pulse with high resolution is critical for NDCX-1A, and an understanding of the accessible parameter space is modeled using the LSP particle-in-cell (PIC) code. The design and preliminary experimental results for an ion beam probe which measures the total beam current at the focal plane as a function of time are summarized.

 
 
TPAT081 Observation of Electron-Ion Effects at RHIC Transition beam-losses, emittance, vacuum, octupole 4087
 
  • J. Wei, M. Bai, M. Blaskiewicz, P. Cameron, R. Connolly, A. Della Penna, W. Fischer, H. Huang, U. Iriso, R.C. Lee, R.J. Michnoff, V. Ptitsyn, T. Roser, T. Satogata, S. Tepikian, L. Wang, S.Y. Zhang
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

Electron cloud is found to be a serious obstacle on the upgrade path of the Relativistic Heavy Ion Collider (RHIC). At twice the design number of bunches, electron-ion interactions cause significant instability, emittance growth, and beam loss along with vacuum pressure rises when the beam is accelerated across the transition.

 
 
TPAT087 The Effect of Magnetic Field Errors on Dynamical Friction in Electron Coolers simulation, ion, positron, luminosity 4206
 
  • D.L. Bruhwiler, D.T. Abell, R. Busby, S.A. Veitzer
    Tech-X, Boulder, Colorado
  • A.V. Fedotov, V. Litvinenko
    BNL, Upton, Long Island, New York
  Funding: Work supported by US DOE grants DE-FG03-01ER83313 and DE-FG03-95ER40926.

A proposed luminosity upgrade to the Relativistic Heavy Ion Collider (RHIC) includes a novel electron cooling section,* which would use ~55 MeV electrons to cool fully-ionized 100 GeV/nucleon gold ions. A strong (1-5 T) solenoidal field will be used to magnetize the electrons and thus enhance the dynamical friction force on the ions. The physics of magnetized friction is being simulated for RHIC parameters, using the VORPAL code.** Most theoretical treatments for magnetized dynamical friction do not consider the effect of magnetic field errors, except in a parametric fashion.*** However, field errors can in some cases dramatically reduce the velocity drag and corresponding cooling rate. We present a simple analytical model for the magnetic field errors, which must be Lorentz transformed into the beam frame for use in our simulations. The simulated dynamical friction for the case of a perfect solenoidal field will be compared with results from this new model, for parameters relevant to RHIC.

*Fedotov et al., Proc. 33rd ICFA Adv. Beam Dynamics Workshop (2004). **Nieter & Cary, J. Comp. Phys. 196 (2004). ***Parkhomchuk, Nucl. Instr. Meth. Phys. Res. A 441 (2000).

 
 
TPAT089 Cooling Dynamics Studies and Scenarios for the RHIC Cooler ion, luminosity, emittance, simulation 4236
 
  • A.V. Fedotov, I. Ben-Zvi, V. Litvinenko
    BNL, Upton, Long Island, New York
  • A.O. Sidorin, A.V. Smirnov, G.V. Troubnikov
    JINR, Dubna, Moscow Region
  Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-98CH10886

In this paper, we discuss various cooling dynamics studies for RHIC, such as an equilibrium process between intra-beam scattering within ion bunch and electron cooling, critical number of electrons needed, magnetized cooling logarithm and resulting requirements on parameters of electron beam, effects of solenoid errors, etc. We also present simulations of various possibilities of using electron cooling at RHIC, which includes cooling at the top energy, pre-cooling at low energy, aspects of transverse and longitudinal cooling and their impact on the luminosity. Electron cooling at various collision energies both for heavy ions and protons is also discussed.

 
 
TPAT090 Simulations of High-Energy Electron Cooling ion, luminosity, simulation, emittance 4251
 
  • A.V. Fedotov, I. Ben-Zvi, Yu.I. Eidelman, V. Litvinenko, N. Malitsky
    BNL, Upton, Long Island, New York
  • D.L. Bruhwiler
    Tech-X, Boulder, Colorado
  • I.N. Meshkov, A.O. Sidorin, A.V. Smirnov, G.V. Troubnikov
    JINR, Dubna, Moscow Region
  Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-98CH10886.

High-energy electron cooling of RHIC presents many unique features and challenges. An accurate estimate of the cooling times requires a detailed calculation of the cooling process, which takes place simultaneously with various diffusive mechanisms in RHIC. In addition, many unexplored effects of high-energy cooling in a collider complicate the task of getting very accurate estimates of cooling times. To address these high-energy cooling issues, a detailed study of cooling dynamics based on computer codes is underway at Brookhaven National Laboratory. In this paper, we present an update on code development and its application to the high-energy cooling dynamics studies for RHIC.

 
 
TPAT092 Numerical Studies of the Friction Force for the RHIC Electron Cooler ion, simulation, plasma, space-charge 4278
 
  • A.V. Fedotov, I. Ben-Zvi, V. Litvinenko
    BNL, Upton, Long Island, New York
  • D.T. Abell, D.L. Bruhwiler, R. Busby, P. Schoessow
    Tech-X, Boulder, Colorado
  Funding: Work performed under the auspices of the U.S. Department of Energy.

Accurate calculation of electron cooling times requires an accurate description of the dynamical friction force. The proposed RHIC cooler will require ~55 MeV electrons, which must be obtained from an RF linac, leading to very high transverse electron temperatures. A strong solenoid will be used to magnetize the electrons and suppress the transverse temperature, but the achievable magnetized cooling logarithm will not be large. Available formulas for magnetized dynamical friction are derived in the logarithmic approximation, which is questionable in this regime. In this paper, we explore the magnetized friction force for parameters of the RHIC cooler, using the VORPAL code.* VORPAL can simulate dynamical friction and diffusion coefficients directly from first principles.** Various aspects of the friction force, such as dependence on magnetic field, scaling with ion charge number and others, are addressed for the problem of high-energy electron cooling in the RHIC regime.

*C. Nieter & J.R. Cary, J. Comp. Phys. 196 (2004), p. 448. **D.L. Bruhwiler et al., Proc. 33rd ICFA Advanced Beam Dynamics Workshop (2004).

 
 
TPAT095 Beam Induced Pressure Rise at RHIC ion, background, proton, luminosity 4308
 
  • S.Y. Zhang, J.G. Alessi, M. Bai, M. Blaskiewicz, P. Cameron, K.A. Drees, W. Fischer, J. Gullotta, P. He, H.-C. Hseuh, H. Huang, U. Iriso, R.C. Lee, V. Litvinenko, W.W. MacKay, T. Nicoletti, B. Oerter, S. Peggs, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, L. Smart, L. Snydstrup, P. Thieberger, D. Trbojevic, L. Wang, J. Wei, K. Zeno
    BNL, Upton, Long Island, New York
  Beam induced pressure rise in RHIC warm sections is currently one of the machine intensity and luminosity limits. This pressure rise is mainly due to electron cloud effects. The RHIC warm section electron cloud is associated with longer bunch spacings compared with other machines, and is distributed non-uniformly around the ring. In addition to the countermeasures for normal electron cloud, such as the NEG coated pipe, solenoids, beam scrubbing, bunch gaps, and larger bunch spacing, other studies and beam tests toward the understanding and counteracting RHIC warm electron cloud are of interest. These include the ion desorption studies and the test of anti-grazing ridges. For high bunch intensities and the shortest bunch spacings, pressure rises at certain locations in the cryogenic region have been observed during the past two runs. Beam studies are planned for the current 2005 run and the results will be reported.

Work performed under the auspices of the US Department of Energy.

 
 
TPAT097 CLIC Drive Beam and LHC Based FEL-Nucleus Collider collider, photon, linac, ion 4320
 
  • O. Yavas
    Ankara University, Faculty of Engineering, Tandogan, Ankara
  • H.-H. Braun, R. Corsini
    CERN, Geneva
  • S. Sultansoy
    Gazi University, Faculty of Science and Arts, Ankara
  Funding: Ankara University, Ankara, TURKEY.

Main parameters of CLIC-LHC based FEL-Nucleus collider are determined. The matching of beam structures for maximum luminosity is studied. The advantages of the collider with respect to the traditional Nuclear Resonance Fluorescence (NRF) methods are presented considering (/Gamma-/Gamma(prime)) reactions. Determination of unknown decay width, spin and parity of excited levels is discussed for Pb nucleus.

 
 
TPAT099 Main Parameters of ILC-Tevatron Based Lepton-Hadron and Photon-Hadron Colliders collider, luminosity, photon, proton 4335
 
  • S. Sultansoy
    Gazi University, Faculty of Science and Arts, Ankara
  • O. Cakir, A.K. Ciftci
    Ankara University, Faculty of Sciences, Tandogan/Ankara
  • E. Recepoglu
    Turkish Atomic Energy Authority, Ankara
  • O. Yavas
    Ankara University, Faculty of Engineering, Tandogan, Ankara
  Funding: Ankara University.

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

 
 
TOAB002 First Results from the VUV FEL at DESY radiation, photon, emittance, undulator 127
 
  • B. Faatz
    DESY, Hamburg
  The VUV-FEL is an upgrade of the TTF1-FEL, which was taken in operation until end 2002. During this phase of the project it showed lasing in the wavelength range from 80-120 nm and it successfully provided beam for two pilot experiments. For over one year, the machine has been redesigned and upgraded, based on the experience gained during the first phase, to a user facility extending the wavelength range. Commissioning started in february 2004. In this contribution, the characterization of the VUV-FEL will be discussed, its electron beam parameters, photon beam properties and the status of the coming user experiments.  
 
TOAB007 Femtoslicing in Storage Rings laser, radiation, photon, undulator 590
 
  • S. Khan
    BESSY GmbH, Berlin
  Funding: Funded by the Bundesministerium für Bildung und Forschung and by the Land Berlin.

The generation of ultrashort synchrotron radiation pulses by laser-induced energy modulation of electrons and their subsequent transverse displacement, now dubbed "femtoslicing," was demonstrated at the Advanced Light Source in Berkeley. More recently, a femtoslicing user facility was commissioned at the BESSY storage ring in Berlin, and another project is in progress at the Swiss Light Source. The paper reviews the principle of femtoslicing, its merits and shortcomings, as well as the variations of its technical implementation. Various diagnostics techniques to detect successful laser-electron interaction are discussed and experimental results are presented.

 
 
TOAD001 Techniques for Pump-Probe Synchronisation of Fsec Radiation Pulses laser, photon, booster, undulator 59
 
  • H. Schlarb
    DESY, Hamburg
  The increasing interest on the production of ultra-short photon pulses in future generations of Free-Electron Lasers operating in the UV, VUV or X-ray regime demands new techniques to reliably measure and control the arrival time of the FEL-pulses at the experiment. For pump-probe experiments using external optical lasers the desired synchronisation is in the order of tens of femtoseconds, the typical duration of the FEL pulse. Since, the accelerators are large scale facilities of the length of several hundred meters or even kilometers, the problem of synchronisation has to be attacked twofold. First, the RF acceleration sections upstream of the magnetic bunch compressors need to be stabilised in amplitude and phase to high precision. Second, the remain electron beam timing jitter needs to be determined with femtosecond accuracy for off-line analysis. In this talk, several techniques using the electron or the FEL beam to monitor the arrival time are presented, and the proposed layout of the synchronisation system for the European XFEL towards the 10 fsec regime.  
 
TOAD004 The Possibility of Noninvasive Micron High Energy Electron Beam Size Measurement Using Diffraction Radiation target, radiation, background, emittance 404
 
  • G.A. Naumenko, A. Potylitsyn
    Tomsk Polytechnic University, Physical-Technical Department, Tomsk
  • S. Araki, A. Aryshev, H. Hayano, V. Karataev, T. Muto, J.U. Urakawa
    KEK, Ibaraki
  • D. Cline, Y. Fukui
    UCLA, Los Angeles, California
  • R. Hamatsu
    TMU, Hatioji-shi,Tokyo
  • M.C. Ross
    SLAC, Menlo Park, California
  During the last years a noninvasive method for beam size measurement based on the optical diffraction radiation (ODR) has been in progress (P. Karataev, et al., Physical Review Letters 93, 244802 (2004). However this technique encounters with hard sensitivity limitation for electron energies larger than several GeV. For example, for SLAC conditions the sensitivity of this method is 4 orders smaller than an appropriate one. We suggest to use a "dis-phased" slit target, where two semi-planes are turned with respect to each other at a small "dis-phased" angle. In order to ensure the interference between the diverged radiation beams we use a cylindrical lens. This method has much better sensitivity and resolution. A "dis-phased" angle 10 milliradians gives the optimal sensitivity to 5 microns transversal beam size. The theoretical model for calculating the ODR radiation from such targets (including focusing by cylindrical lens) is presented. It is shown that the sensitivity of this method does not depend on the Lorenz-factor directly. The target with the "dis-phased" angle 6.2 milliradians and the slit width 425 microns was manufactured for experimental test. Some preliminary experimental results are presented.  
 
TOAD005 Observation of Frequency Locked Coherent Transition Radiation radiation, plasma, vacuum, single-bunch 452
 
  • R.A. Marsh, A.S. Kesar, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts
  Funding: This work was supported by the Department of Energy, High Energy Physics, under contract DE-FG02-91ER40648.

Measurements of frequency locked, coherent transition radiation (CTR) were performed at the 17 GHz high-gradient accelerator facility built by Haimson Research Corporation at MIT PSFC. CTR produced from a metallic foil placed in the beam path was extracted through a window, and measured with a variety of detectors, including: diode, Helium cooled Si Bolometer, and double heterodyne receiver system. The angular energy distribution measured by the diode and bolometer are in agreement and consistent with calculations for a 15 MeV 200 mA 110 ns beam of 1 ps bunches. Heterodyne receiver measurements were able to show frequency locking, namely inter-bunch coherence at integer multiples of the accelerator RF frequency of 17.14 GHz. At the locked frequencies the power levels are enhanced by the number of bunches in a single beam pulse. The CTR was measured as a comb of locked frequencies up to 240 GHz, with a bandwidth of 50 MHz.

 
 
TOPC001 Visualizing Electron Beam Dynamics and Instabilities with Synchrotron Radiation at the APS undulator, storage-ring, photon, diagnostics 74
 
  • B.X. Yang, A.H. Lumpkin
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38.

The Advanced Photon Source (APS) is a third generation hard x-ray source serving a large user community. In order to characterize the high-brilliance beams, the APS diagnostics beamlines have been developed into a full photon diagnostics suite. We will describe the design and capabilities of the APS visible light imaging line, the bend magnet x-ray pinhole camera, and a unique diagnostics undulator beamline. Their primary functions are to support the APS user operations by providing information on beam sizes (20 - 100 micrometers), divergence (3 – 25 microradians), and bunch length (20 – 50 ps). Through the use of examples, we will show how these complementary imaging tools are used to visualize the electron dynamics and investigate beam instabilities. Special emphasis will be put on the use of undulator radiation, which is uniquely suitable for time-resolved imaging of electron beam with high spatial resolution, and for measurements of longitudinal beam properties such as beam energy spread and momentum compaction.

 
 
TOPC002 Residual-Gas-Ionization Beam Profile Monitors in RHIC emittance, coupling, background, heavy-ion 230
 
  • R. Connolly, R.J. Michnoff, S. Tepikian
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract #DE-AC02-98CH10886 under the auspices of the U.S. Department of Energy.

Four ionization profile monitors (IPMs) are in RHIC to measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. During the last two years both the collection accuracy and signal/noise ratio have been improved. An electron source is mounted across the beam pipe from the collector to monitor microchannel plate (MCP) aging and the signal electrons are gated to reduce MCP aging and to allow charge replenishment between single-turn measurements. Software changes permit simultaneous measurements of any number of individual bunches in the ring. This has been used to measure emittance growth rates on six bunches of varying intensities in a single store. Also the software supports FFT analysis of turn-by-turn profiles of a single bunch at injection to detect dipole and quadrupole oscillations.

 
 
TOPB001 Methods of Attosecond X-Ray Pulse Generation laser, undulator, wiggler, radiation 39
 
  • A. Zholents
    LBNL, Berkeley, California
  Funding: This work was supported by the Director, Office of Science of the U. S. Department of Energy under Contract No. DE-AC03-76SF00098.

Our attitude towards attosecond x-ray pulses has changed dramatically over the past several years. Not long ago x-ray pulses with a duration of a few hundred attoseconds were just science fiction for most of us, but they are already a tool for some researchers in present days. Breakthrough progress in the generation of solitary soft x-ray pulses of attosecond duration has been made by the laser community. Following this lead, people in the free electron laser community have begun to develop new ideas on how to generate attosecond x-ray pulses in the hard x-ray energy range. In this report I will review some of these ideas.

 
 
TOPB003 Progress in Large-Scale Femtosecond Timing Distribution and RF-Synchronization laser, polarization, space-charge, feedback 284
 
  • F.X. Kaertner, H. Byun, J. Chen, F J. Grawert, F.O. Ilday, J. Kim, A. Winter
    MIT, Cambridge, Massachusetts
  For future advances in accelerator physics in general and seeding of free electron lasers (FELs) in particular, precise synchronization between low-level RF-system, photo-injector laser, seed radiation as well as potential probe lasers at the FEL output is required. We propose a modular system based on optical pulse trains from mode-locked lasers for timing distribution and timing information transfer in the optical domain to avoid detrimental effects due to amplitude to phase conversion in photo detectors. Synchronization of various RF- and optical sub-systems with femtosecond precision over distances of several hundred meters can be achieved. First experimental results and limitations of the proposed scheme for timing distribution are discussed.  
 
TOPB004 Overview of Energy Recovery Linacs emittance, linac, gun, radiation 382
 
  • I.V. Bazarov
    Cornell University, Department of Physics, Ithaca, New York
  Funding: Supported by the NSF.

Existing Energy Recovery Linacs (ERLs) are successfully operated as kW-class average power infrared Free Electron Lasers (FELs). Various groups worldwide actively pursue ERLs as a technology of choice for a number of new applications. These include high brilliance light sources in a wide range of photon energies utilizing both spontaneous and FEL radiation production techniques, electron cooling of ion beams, and ERL-based electron-ion collider. All of these projects seek in various ways to extend performance parameters possible in ERLs beyond what has been achieved in existing relatively small scale demonstration facilities. The demand is for much higher average currents, significantly larger recirculated beam energies and powers and substantially improved electron sources. An overview of the ongoing ERL projects will be presented along with the summary of the progress that is being made in addressing the outstanding issues in this type of accelerators.

 
 
TPPE001 The HERA Volume H- Source plasma, extraction, emittance, vacuum 788
 
  • J. Peters
    DESY, Hamburg
  Funding: The support of EEC (Contract HPRI-CT-2001-50021) is gratefully acknowledged.

The HERA RF-Volume Source is the only source that delivers routinely a H – current of 40 mA without Cs. It has been running for years without interruption for maintenance. The production mechanism for H – ions in this type of source is still under discussion. Laser photodetachment measurements have been done at DESY in order to measure the H – distribution in the source. The measurements were done also under extraction conditions at high voltage. The dependency of the quality of the Hminus beam on the frequency was investigated. A frequency range of 1.65 – 9 Mhz was scanned and the emittance was measured for several Hminus currents up to 40 mA. The results of our investigations make further source improvements possible. Recently currents of 60 mA were reached.

 
 
TPPE003 Analysis of Multigrid Extraction Plasma Meniscus Formation plasma, ion, extraction, proton 862
 
  • M. Cavenago
    INFN/LNL, Legnaro, Padova
  • V. Antoni, F. Sattin
    CNR/RFX, Padova
  • A. Tanga
    MPI/IPP, Garching
  Funding: INFN-LNL, CNR-RFX.

Effects of plasma meniscus on the emittance in negative ion source proposed for spallation sources or neutral beam injectors (NBI) for tokamaks are particularly interesting to study with fluid models because: 1) at least three different charged fluid can be recognised: the thermalized and fully magnetized electrons; the slightly magnetized and roughly thermalized positive ions; the negative ions, typically formed within few cm from meniscus; 2) different implementation of the magnetic filter system need to be compared; 3) optimization of electron dump and outlet electrode strongly depends on plasma meniscus contact point. With reasonable assumption on system geometry, 2D and 3D charged fluid quation for the selfconsistent electrostatic field can be written and effect of grid aperture is investigated. Moreover, these equations are easily implemented into a multiphysics general purpose program. Preliminary results are described, and compared to existing codes.

 
 
TPPE004 The Production of Negative Lithium Beams by Charge Exchange in Cesium Vapours ion, target, ion-source, vacuum 898
 
  • M. Re, F. Chines, G. Cuttone, M. Menna, E. Messina
    INFN/LNS, Catania
  • J.-C. Bilheux, D.W. Stracener
    ORNL, Oak Ridge, Tennessee
  These measurements were carried out at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory (ORNL-HRIBF) by researchers from the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Catania, Italy and local staff. The Charge Exchange Cell (CEC) consisted of a vacuum chamber containing cesium vapours at a variable temperature, T, in which positive ions accelerated from an ion source were transformed into negative ones by collisions with the Cs atoms. The main goal of this test was to measure the production efficiency for 7Li- ions at different operating conditions, such as 7Li+ beam energy (5 to 55 keV) and Cs temperature (190 to 300 °C). Moreover, the efficiency measurements performed with a 6Li+ projectile beam gave clear indications about the isotopic shift effect. These results are useful to estimate the charge exchange efficiency for 8, 9Li, which will be the first radioactive beams to be produced at the EXCYT facility (EXotics with CYclotron and Tandem). The data showed that the charge exchange efficiency at the minimum energy suitable for beam handling (20-25 keV) is around 1%.  
 
TPPE015 The Effusive-Flow Properties of Target/Vapor-Transport Systems for Radioactive Ion Beam Applications target, ion, ion-source, cathode 1422
 
  • Y. Kawai, G. Alton, Y. Liu
    ORNL, Oak Ridge, Tennessee
  Funding: Research at ORNL is supported by the U.S. DOE under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

Radioactive atoms produced by the ISOL technique must diffuse from a target, effusively flow to an ion source, be ionized, be extracted, and be accelerated to research energies in a time commensurate with the lifetime of the species of interest. We have developed a fast valve system (closing time ~100 us) that can be used to accurately measure the effusion times of chemically active or inactive species through arbitrary geometry and size vapor transport systems with and without target material in the reservoir. The effusive flow times are characteristic of the system and thus serve as figures of merit for assessing the quality of a given vapor transport system as well as for assessing the permeability properties of a given target design. This article presents effusive flow data for noble gases flowing through a target reservoir and ion source system routinely used to generate radioactive species at the HRIBF with and without disks of 6 times and 10 times compressed Reticulated Vitreous Carbon Foam (RVCF) with the objective of determining the added delay time associated with each of these target matrices.

 
 
TPPE016 ISOL Targets Prepared with a New Paint Infiltration Coating Method target, ion, vacuum 1508
 
  • Y. Kawai, G. Alton, J. O. Kiggans, D.W. Stracener
    ORNL, Oak Ridge, Tennessee
  Funding: Research at ORNL is supported by the U.S. DOE under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

A new infiltration paint coating method has been developed for fabricating ISOL targets for radioactive ion beam applications. The technique has been shown to be inexpensive, fast, and almost universal for the uniform deposition of many refractory target materials onto the interior surfaces of complex geometry matrices, such as Reticulated-Vitreous-Carbon-Foam (RVCF). The process yields robust, highly permeable targets with fast diffusion and release properties. We demonstrate the viability of the technique for coating forms of RVCF compressed by factors of 6 and 10 with materials to form targets for use at high energy facilities such as RIA. The use of compressed RVCF, coated with an optimum thickness of target material, reduces target lengths to practical values, while preserving high permeability. We calculate thermal conductivities and diffusion for various targets on 6xRVCF and 10xRVCF.

 
 
TPPE017 A New Broadband Microwave Frequency Device for Powering ECR Ion Sources ion, ion-source, radiation, injection 1529
 
  • Y. Kawai, G. Alton, Y. Liu
    ORNL, Oak Ridge, Tennessee
  Funding: Research at ORNL is supported by the U.S. DOE under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

The multiple discrete frequency technique has been used to improve the performance of conventional B-field configuration ECR ion sources. However, the practical application of this technique is very costly, requiring multiple independent single-frequency rf power supplies and complicated rf injection systems. Broadband sources of rf power offer a low-cost and more effective method for increasing the physical size of the ECR zone within these ion sources. An Additive White Gaussian Noise Generator (AWGNG) system for injecting broadband rf power into these ion sources has been developed in conjunction with a commercial firm. The noise generator, in combination with an external oscillator and a traveling wave tube amplifier, can be used to generate broadband rf power without modifying the injection system. The AWGNG and its use for enhancing the performance of conventional B-field configuration ECR ion sources will be described.

 
 
TPPE022 First Results on the Path Towards a Microwave-Assisted H- Ion Source ion, ion-source, plasma, SNS 1784
 
  • R. Keller, P.A. Luft, M. T. Monroy, A. Ratti, M.J. Regis, D. L. Syversrud, J.G. Wallig
    LBNL, Berkeley, California
  • D.E. Anderson, R.F. Welton
    ORNL, Oak Ridge, Tennessee
  Funding: This work supported by Office of Basic Energy Sciences, U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

A novel concept for creating intense beams of negative hydrogen ion beams is presented. In this approach, an ECR ion source operating at 2.45 GHz frequency is utilized as a primary plasma generator and coupled to an SNS-type multi-cusp H- ion source. The secondary source is driven by chopped dc power avoiding the use of filaments or of an internal rf antenna. The development of the new ion source is aimed at the future beam-power goal of 3 MW for the Spallation Neutron Source (SNS) that will be pursued after the start of SNS operations, but application to other proton driver accelerators that include an accumulator ring is feasible as well. The first two phases of this development effort have been successfully completed: assembly of a test stand and verification of the performance of an rf-driven SNS ion-source prototype; and extraction of electrons with more than 350 mA current from a 2.45-GHz ECR ion source obtained on loan from Argonne National Laboratory. The next goal is the demonstration of actual H- ion production by this novel, hybrid ion source. This paper describes the source principle and design in detail and reports on the current status of the development work.

 
 
TPPE028 In-Situ Electron Cyclotron Resonance (ECR) Plasma Potential Determination Using an Emissive Probe plasma, ion, ion-source, monitoring 2035
 
  • F.W. Meyer, Y. Liu
    ORNL, Oak Ridge, Tennessee
  • H.J. You
    Hanyang University, Seoul
  Funding: This research was sponsored by the U.S. DOE under contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. HJY acknowledges support from the Korean Science Education Foundation (KOSEF).

In this paper, real-time, in-situ, plasma potential measurements are reported for an ECR ion source and correlated with extracted beam characteristics. The local real-time plasma potential of the ORNL CAPRICE ECR ion source was measured using an emissive probe, which was inserted perpendicularly from the plasma chamber wall at the mid-plane of the ECR zone between one of the six radial loss cones of the magnetic field structure, where perturbation of the main ECR plasma is expected to be small. Slots machined through the plasma- and puller-electrodes at the plasma chamber wall radius permitted insertion of the probe from the extraction side of the ECR source without perturbation of the coaxial microwave injection. The emissive probe technique permits plasma potential determination independent of plasma conditions and avoids problems related to probe geometry. The probe loop tip was pointed toward the chamber center in a radial plane and was located about 5 mm outside of the ECR zone. Details of the measurements, and a comparison with an external-beam-deceleration-based plasma potential determination will be presented.

 
 
TPPE029 Measurements of Ion Selective Containment on the RF Charge Breeder Device BRIC ion, extraction, simulation, vacuum 2065
 
  • V. Variale, A. Boggia, T. Clauser, A. Rainò, V. Valentino
    INFN-Bari, Bari
  • P.A. Bak, M. A. Batazova, G.I. Kuznetsov, S. Shiyankov, B.A. Skarbo
    BINP SB RAS, Novosibirsk
  • G. Verrone
    Università e Politecnico di Bari, Bari
  Funding: Istituto Nazionale Fisica Nucleare.

The "charge state breeder" BRIC (BReeding Ion Charge) is based on an EBIS source and it is designed to accept Radioactive Ion Beam (RIB) with charge +1, in a slow injection mode, to increase their charge state up to +n. BRIC has been developed at the INFN section of Bari (Italy) during these last 3 years with very limited funds. Now, it has been assembled at the LNL (Italy) where are in progress the first tests as stand alone source. The new feature of BRIC, with respect to the classical EBIS, is given by the insertion, in the ion drift chamber, of a Radio Frequency (RF) Quadrupole aiming to filtering the unwanted elements and then making a more efficient containment of the wanted ions. In this contribution, the measurements of the selective effect on the ion charge state containement of the RF quadrupole field, applied on the ion chamber, will be reported and discussed. The ion charge state analisys of the ions trapped in BRIC seem confirm, as foreseen by simulation results carried out previously, that the selective containment can be obtained. A modification of the collector part to improve the ion extraction of BRIC will be also presented and shortly discussed.

 
 
TPPE030 A Method to Polarize Stored Antiprotons to a High Degree antiproton, target, polarization, lattice 2158
 
  • A. Lehrach, S. Martin, F. Rathmann
    FZJ, Jülich
  • P. Lenisa
    INFN-Ferrara, Ferrara
  • I.N. Meshkov, A.O. Sidorin, A.V. Smirnov
    JINR, Dubna, Moscow Region
  • C. Montag
    BNL, Upton, Long Island, New York
  • E. Steffens
    University of Erlangen-Nürnberg, Physikalisches Institut II, Erlangen
  • C.-A. Wiedner
    UGS, Langenbernsdorf
  The PAX collaboration proposes a method to produce intense beams of polarized antiprotons. Polarized antiprotons can be produced in a storage ring by spin-dependent interaction in a purely hydrogen gas target. The polarizing process is based on spin transfer from the polarized electrons of the target atoms to the orbiting antiprotons. After spin filtering for about two beam lifetimes at energies of about 50-100 MeV using a dedicated large acceptance ring, the antiproton polarization would reach P=0.2-0.4. In the presentation, beside a description of the polarization technique and its potentiality, a description of the ideal characterstics of the antiproton polarizer will be given.

hep-ph/0411046

 
 
TPPE035 Efficiency of the Fermilab Electron Cooler’s Collector cathode, permanent-magnet, gun, simulation 2387
 
  • L.R. Prost, A.V. Shemyakin
    Fermilab, Batavia, Illinois
  Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

The newly installed high-energy Recycler Electron Cooling system (REC) at Fermilab will work at an electron energy of 4.34 MeV and a DC beam current of 0.5 A in an energy recovery scheme. For reliable operation of the system, the relative beam current loss must be maintained to levels < 3.e-5. Experiments have shown that the loss is determined by the performance of the electron beam collector, which must retain secondary electrons generated by the primary beam hitting its walls. As a part of the Electron cooling project, the efficiency of the collector for the REC was optimized, both with dedicated test bench experiments and on two versions of the cooler prototype. We find that to achieve the required relative current loss, an axially-symmetric collector must be immersed in a transverse magnetic field with certain strength and gradient prescriptions. Collector efficiencies in various magnetic field configurations, including without a transverse field on the collector, are presented and discussed

 
 
TPPE036 Progress of the BEPCII Linac Upgrade positron, linac, gun, target 2416
 
  • G. Pei
    IHEP Beijing, Beijing
  BEPCII-an upgrade project of the BEPC is a factory type of e+e- collider. It requires its injector linac to have a higher beam energy (1.89 GeV) for on-energy injection and a higher beam current (40 mA e+ beam) for a higher injection rate (=50 mA/min.). The low beam emittance (1.6pmm-mrad for e+ beam, and 0.2pmm-mrad for 300 mA e- beam) and low beam energy spread (±0.5%) are also required to meet the storage ring acceptance. Hence we need a new electron gun system, a new positron source, a much higher power and more stable RF system with its phasing loops, and a new beam tuning system with orbit correction. Up to date, all system design and fabrication work have been completed. And in five months from May 1st of 2004, the positron production system–from the electron gun to the positron source, has been installed into the tunnel. In this paper, we will introduce major upgrades of each system, and present the recent beam commissioning.  
 
TPPE037 Relative Contribution of Volume and Surface-Plasma Generation of Negative Ions in Gas Discharges ion, plasma, ion-source, cathode 2482
 
  • V.G. Dudnikov
    BTG, New York
  The relative contribution of volume and surface-plasma generation of extracted ?- ions in gas discharge sources will be analyzed. At the present time, it is well known that surface-plasma generation of extracted ?- ion is dominate above volume processes in discharges with admixture of cesium or other catalysts with low ionization potential. We will attract attention to evidences, that surface-plasma generation can be enhanced in high density discharges without cesium after electrode activation by high temperature conditioning in discharge. A diffusion of impurity with a low ionization potential can be a reason of observed enhancement of H- emission. For the effective generation of ?- ion beams in discharge without cesium, it is necessary to optimize surface-plasma generation of extracted ?- ion. Such optimization allows considerable improvement of ?-/D- sources characteristics.  
 
TPPE038 Thermal Hydraulic Design of PWT Accelerating Structures feedback, linear-collider, simulation, collider 2524
 
  • D. Yu, A. Baxter, P. Chen, M. Lundquist, Y. Luo
    DULY Research Inc., Rancho Palos Verdes, California
  Funding: Work supported by DOE SBIR Grant No. DE-FG02-03ER83846.

Microwave power losses on the surfaces of accelerating structures will transform to heat which will deform the structures if it is not removed in time. Thermal hydraulic design of the disk and cooling rods of a Plane Wave Transformer (PWT) structure is presented. Experiments to measure the hydraulic (pressure vs flow rate) and cooling (heat removed vs flow rate) properties of the PWT disk are performed, and results compared with simulations using Mathcad models and the COSMOSM code. Both experimental and simulation results showed that the heat deposited on the structure could be removed effectively using specially designed water-cooling circuits and the temperature of the structure could be controlled within the range required.

 
 
TPPE039 Development of Advanced Models for 3D Photocathode PIC Simulations simulation, laser, cathode, gun 2583
 
  • D.A. Dimitrov, D.L. Bruhwiler, J.R. Cary, P. Messmer, P. Stoltz
    Tech-X, Boulder, Colorado
  • D.W. Feldman, P.G. O'Shea
    IREAP, College Park, Maryland
  • K. Jensen
    NRL, Washington, DC
  Funding: This work is supported by the U.S. DOE, use of NERSC supercomputer facilities, and the Joint Technology office (JTO).

Codes for simulating photocathode electron guns invariably assume the emission of an idealized electron distribution from the cathode, regardless of the particular particle emission model that is implemented. The output of such simulations, a relatively clean and smooth distribution with very little variation as a function of the azimuthal angle, is inconsistent with the highly irregular and asymmetric electron bunches seen in experimental diagnostics. To address this problem, we have implemented a recently proposed theoretical model* that takes into account detailed solid-state physics of photocathode materials in the VORPAL particle-in-cell code.** Initial results from 3D simulations with this model and future research directions will be presented and discussed.

*K.L. Jensen, D.W. Feldman, M. Virgo, and P.G. O'Shea, Phys. Rev. ST Accel. Beams, 6:083501, 2003. **C. Nieter and J.R. Cary, J. Comp. Phys. 196 (2004), p. 448.

 
 
TPPE041 Multi-Alkali Photocathode Development at Brookhaven National Lab for Application in Superconducting Photoinjectors laser, cathode, vacuum, gun 2672
 
  • A. Burrill, I. Ben-Zvi, D. Pate, T. Rao, Z. Segalov
    BNL, Upton, Long Island, New York
  • D. Dowell
    SLAC, Menlo Park, California
  In this paper we will report our progress on the development of cesium potassium antimonide photocathodes and their application in superconducting photoinjectors. Quantum efficiencies of 2-3 % at 545 nm, and 10% at 365 nm have been routinely obtained in the test stand, and electron emission uniformity, quantum efficiency at a variety of wavelengths, and lifetime under different vacuum conditions has been well characterized. The extraction of high charge per laser pulse will also be addressed in addition to the comparison of results from two different deposition techniques.  
 
TPPE042 Study of Secondary Emission Enhanced Photoinjector cathode, gun, space-charge, scattering 2711
 
  • X.Y. Chang, I. Ben-Zvi, A. Burrill, P.D.J. Johnson, J. Kewisch, T. Rao, Z. Segalov, Y. Zhao
    BNL, Upton, Long Island, New York
  The secondary emission enhanced photoinjector (SEEP) is a very promising new approach to the generation of high-current, high-brightness electron beams. Primary electrons with a few thousand electron-volts of energy strike a specially prepared diamond window. The large Secondary Electron Yield (SEY) provides a multiplication of the number of electrons by about two orders of magnitude. The secondary electrons drift through the diamond under an electric field and emerge into the accelerating proper of the “gun” through a Negative Electron Affinity (NEA) surface of the diamond (Hydrogen terminated). We present the calculation of heating power sources and the temperature distribution in details. Some properties of the secondary electron beam related to beam dynamics are also reported. The results show feasibility of this kind of cathode.  
 
TPPE043 Electron Beam Generation and Transport for the RHIC Electron Cooler emittance, space-charge, linac, cathode 2774
 
  • J. Kewisch, I. Ben-Zvi, X.Y. Chang
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy.

An electron cooler, based on an Energy Recovery Linac (ERL) is under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. This will be the first electron cooler operating at high energy with bunched beams. A better understanding of the cooling process and more accurate measurements of Intra Beam Scattering in RHIC have imposed increased requirements on the electron accelerator: Besides a doubling of the bunch charge to 20 nC, the strength of the cooling solenoid was increased five-fold to 5 Tesla. The magnetic field on the cathode should be increased to 500 Gauss to match the magnetization required in the cooling solenoid. This paper reports the measures taken to minimize the electron beam emittance in the cooling section. The front-to-end simulation using different tracking codes is presented.

 
 
TPPE044 Upgrade of the Fermilab/NICADD Photoinjector Laboratory laser, emittance, quadrupole, linac 2848
 
  • P. Piot, H. Edwards
    Fermilab, Batavia, Illinois
  • M. Huening
    DESY, Hamburg
  • T. W. Koeth
    Rutgers University, The State University of New Jersey, Piscataway, New Jersey
  • J.L. Li, R. Tikhoplav
    Rochester University, Rochester, New York
  Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE, and by NICADD.

The Femilab/NICADD photoinjector laboratory (FNPL) is a 16 MeV electron accelerator dedicated to beam dynamics and advanced accelerator studies. FNPL will soon be capable of operating at 50 MeV, after the installation of a high gradient TESLA cavity. In this paper we present the foreseen design for the upgraded facility along with its performance. We discuss the possible application of 50 MeV beam including the possible use of FNPL as an injector for the superconducting module and test facility (SM&TF).

 
 
TPPE046 Computer Simulation of the UMER Gridded Gun cathode, simulation, gun, space-charge 2908
 
  • I. Haber, S. Bernal, R.A. Kishek, P.G. O'Shea, Y. Zou
    IREAP, College Park, Maryland
  • A. Friedman, D.P. Grote
    LLNL, Livermore, California
  • M. Reiser
    University Maryland, College Park, Maryland
  • J.-L. Vay
    LBNL, Berkeley, California
  Funding: This work is supported by the U.S. DOE under contract Nos. DE-FG02-02ER54672 and DE-FG02-94ER40855 at the UMD, and DE-AC03-76SF00098 at LBNL and W-7405-ENG-48 at LLNL.

The electron source in the University of Maryland Electron Ring (UMER) injector employs a grid 0.15 mm from the cathode to control the current waveform. Under nominal operating conditions, the grid voltage during the current pulse is sufficiently positive relative to the cathode potential to form a virtual cathode downstream of the grid. Three-dimensional computer simulations have been performed that use the mesh refinement capability of the WARP particle-in-cell code to examine a small region near the beam center in order to illustrate some of the complexity that can result from such a gridded structure. These simulations have been found to reproduce the hollowed velocity space that is observed experimentally. The simulations also predict a complicated time-dependent response to the waveform applied to the grid during the current turn-on. This complex temporal behavior appears to result directly from the dynamics of the virtual cathode formation and may therefore be representative of the expected behavior in other sources, such as some photoinjectors, that are characterized by a rapid turn-on of the beam current.

 
 
TPPE047 Fabrication and Measurement of Low Work Function Cesiated Dispenser Photocathodes cathode, laser, dipole, photon 2953
 
  • N.A. Moody, D.W. Feldman, P.G. O'Shea
    IREAP, College Park, Maryland
  • K. Jensen
    NRL, Washington, DC
  Funding: We gratefully acknowledge our funding agencies, the Joint Technology Office and the Office of Naval Research for their support.

Photoinjector performance is a limiting factor in the continued development of high powered FELs and electron beam-based accelerators. Presently available photocathodes are plagued with limited efficiency and short lifetime in an RF-gun environment, due to contamination or evaporation of a photosensitive surface layer. An ideal photocathode should have high efficiency at long wavelengths, long lifetime in practical vacuum environments, and prompt emission. Cathodes with high efficiency typically have limited lifetime, and vice versa, and the needs of the photocathode are generally at odds with those of the drive laser. A potential solution is the low work function dispenser cathode, where lifetime issues are overcome by periodic in situ regeneration that restores the photosensitive surface layer, analogous to those used in the microwave power tube industry. This work reports on the fabrication techniques and performance of cesiated metal photocathodes and cesiated dispenser cathodes, with a focus on understanding and improving quantum efficiency and lifetime, and analyzing issues of emission uniformity. The efficiency versus coverage behavior of cesiated metals is discussed and closely matches that predicted by recent theory.*

*K. L. Jensen, et al., "Photoemission from Low Work Function Coated Metal Surfaces: A Comparison of Theory to Experiment" (this conference).

 
 
TPPE049 Synchronizaiton Between Laser and Electron Beam at Photocathode RF Gun laser, gun, cathode, linac 3079
 
  • A. Sakumi, A. Fukasawa, Y. Muroya, T. Ueda, M. Uesaka, K. Yoshii
    UTNL, Ibaraki
  • K. Dobashi
    NIRS, Chiba-shi
  • N. Kumagai, H. Tomizawa
    JASRI/SPring-8, Hyogo
  • J.U. Urakawa
    KEK, Ibaraki
  The chemical reactions of hot, room temperature and critical water in a time-range of picosecond and sub-picosecond have been carried out by the 18 MeV S-band linac and a Mg photocathode RF gun with the irradiation of third harmonic Ti: Sapphire laser, at Nuclear Engineering Research Laboratory (NERL), the University of Tokyo. Although this short bunch and 100 fs laser light are enough to perform the experiment of radiation chemistry in the time-range of sub-picosecond, the total time-resolution become worse by the instability of synchronization between laser and radio frequency of linac. We found that the fluctuation of room temperature causes the instability, particularly the cycle of turning on/off of the air-conditioner. It is shown that 0.3 °C (peak-to-peak) fluctuation of the laser-room temperature have approximately corresponded to the instability of 6 ps. We are trying to decrease the fluctuation of the room temperature, together with the local temperature stability of the Ti: Sapphire crystal, the pumping laser. Furthermore, we will develop the feed back system for reducing the instability of the synchronization.  
 
TPPE050 Beam Injection in Recirculator SALO injection, quadrupole, gun, focusing 3109
 
  • I.S. Guk, A. Dovbnya, S.G. Kononenko, F.A. Peev, A.S. Tarasenko
    NSC/KIPT, Kharkov
  • J.I.M. Botman, M.J. Van der Wiel
    TUE, Eindhoven
  Possible antetypes of injectors for electron recirculator SALO,* intended for nuclear-physical research, are analyzed. The plan injection of beams in recirculator is offered. Expected parameters of beams are designed.

*I.S. Guk, A.N. Dovbnya, S.G. Kononenko, A.S. Tarasenko, M. van der Wiel, J.I.M. Botman, NSC KIPT accelerator on nuclear and high energy physics, Proceedings of EPAC 2004, Lucerne, Switzerland, p. 761-764.

 
 
TPPE051 The Optimization of the Electron Injector Resonance System Based on the Evanescent Oscillations bunching, simulation, emittance, space-charge 3170
 
  • S.A. Perezhogin, M.I. Ayzatskiy, K. Kramarenko, V.A. Kushnir, V.V. Mytrochenko, Z.V. Zhiglo
    NSC/KIPT, Kharkov
  The report presents the results of the bunching system optimization and electrons motion simulation in the compact S – band injector. The injector consists of the low-voltage diode electron gun and optimized bunching system based on the resonant system with the evanescent oscillations. The amplitude of RF electrical field is increased along the axis of the bunching system. The resonance system optimization allows to obtain electron bunches with the phase length less than 10° (for 70 % particles) at the injector exit.  
 
TPPE052 Characteristics of Electron Beam Produced by Magnetron Diode with a Secondary-Emission Cathode cathode, gun, target, vacuum 3197
 
  • N.G. Reshetnyak, N. Aizatsky, A. Dovbnya, N.A. Dovbnya, V.V. Mytrochenko, V. Zakutin
    NSC/KIPT, Kharkov
  The beam parameters were investigated using an azimuth-sectionalized 8-channel Faraday cup and a 12-channel computer-aided measuring system. The magnetron diode had a cathode (40 mm in diameter) and a 15 mm anode-cathode gap. At a cathode voltage amplitude of 50 kV and a cathode magnetic field of ~1200 Oe, the diode generates a tubular electron beam with an outer diameter of 50 mm, an inner diameter of 44 mm, a beam current of ~50 A. The short time instability of the total beam current, and of the current from each of eight segments of the Faraday cup was estimated to be ~2 … 3%, and long time instability (3 hours) was 57 %. Azimuthal distribution of beam current was investigated versus the amplitude, distribution and direction of the magnetic field. At a cathode magnetic field of 1200 Oe, that falls off inhomogeneity in the vicinity of the Faraday cup down to ~800 Oe, the azimuthal beam current distribution has a ± (3 … 5)%. As the magnetic field strength increases up to ~1700 Oe in the region of beam emergence from the gun and the Faraday cup, the azimuthal inhomogeneity of the beam current increases up to ± (100 … 150)%.  
 
TPPE053 Design Issues for the ILC Positron Source target, positron, photon, undulator 3230
 
  • V. Bharadwaj, Y.K. Batygin, R. Pitthan, D.C. Schultz, J. Sheppard, H. Vincke, J.W. Wang
    SLAC, Menlo Park, California
  • J.G. Gronberg, W. Stein
    LLNL, Livermore, California
  Funding: Work supported by Department of Energy contract DE-AC02-76SF00515.

A positron source for the ILC can be designed using either a multi-GeV electron beam or a multi-MeV photon beam impinging on a metal target. The major issues are: the drive beam, choice of target material, the design of the target station, the capture section, the target vault, and beam transport to the damping ring. In this paper, positron source parameters for the various schemes are outlined and the advantages and disadvantages of each scheme are discussed.

 
 
TPPE055 DC-SC Photoinjector with Low Emittance at Peking University emittance, gun, cathode, laser 3325
 
  • R. Xiang, Y.T. Ding, J. Hao, S.L. Huang, X.Y. Lu, S.W. Quan, B.C. Zhang, K. Zhao
    PKU/IHIP, Beijing
  High average power Free Electron Lasers require the high quality electron beams with the low emittance and the sub-picosecond bunches. The design of DC-SC photoinjector, directly combining a DC photoinjector with an SRF cavity, can produce high average current beam with moderate bunch charge and high duty factor. Because of the DC gun, the emittance increases quickly at the beginning, so a carefully design is needed to control that. In this paper, the simulation of an upgraded design has been done to lower the normalized emittance below 1.5mm·mrad. The photoinjector consists of a DC gap and a 2+1/2-cell SRF cavity, and it is designed to produce 4.2 MeV electron beams at 100pC bunch charge and 81.25MHz repetition rate (8 mA average current).  
 
TPPE059 New Electron Gun System for BEPCII gun, emittance, simulation, linac
 
  • B. Liu, Y.L. Chi, M. Gu, C. Zhang
    IHEP Beijing, Beijing
  The new electron gun system for BEPCII has been put into operation since Nov. 2004. The article describes the design, experiment and operation of this new system. The design current of the gun is 10 A for the pulse lengths of 1 ns, 2.5 ns and 1 μs with repetition rate of 50 Hz. The gun is operated with a pulsed high voltage power supply which can provide up to 200 kV high voltage. Computer simulations have been carried out in the design stage, including simulation of the gun geometry and beam transportation. Some important relation curves are obtained during the experiment. Two-bunch operation is available and some elementary tests have been performed. New scheme of the gun control system based on EPICS is also presented. The real operation shows that the design and manufacturing is basically successful.  
 
TPPE060 Simulation Study of a Thermionic RF Gun for High Brightness and Short Pulse Beam gun, simulation, cathode, extraction 3499
 
  • T. Tanaka, H. Hama, F. Hinode, M. Kawai
    LNS, Sendai
  • A. Miyamoto
    HSRC, Higashi-Hiroshima
  • K. Shinto
    Tohoku University, Sendai
  Characteristics of thermionic RF guns are not understood completely. In particular, measured intense beam emittances extracted from thermionic RF guns do not agree well with simulated values so far. Most of simulation codes solve the equation of electron motion in an intrinsic mode of the RF field calculated by a separated code. The way of such simulation codes is not self-consistent completely. That is probably a major reason for the discrepancy between the experiments and the simulations. One of the other way for a self-consistent simulation codes is to use an FDTD (Finite Difference Time Domain) method. Since the FDTD method can take into account the microwave propagation including the space charge effect and the beam loading self-consistently, we have developed an FDTD code as 3-D Maxwell's equation solver and applied for a study of beam dynamics in a thermionic RF gun. The main purpose of simulaiton study is to obtain overall properties of the beam dynamics at the time. The goal of this simulation study of the thermionic RF gun is to understand correct characteristics of the thermionic RF gun for producing high brightness and short pulse beam.  
 
TPPE061 RF Design and Operating Performance of the BNL/AES 1.3 GHz Single Cell Superconducting RF Photocathode Electron Gun gun, coupling, cathode, superconducting-RF 3514
 
  • M.D. Cole
    AES, Medford, NY
  • I. Ben-Zvi, A. Burrill, H. Hahn, T. Rao, Y. Zhao
    BNL, Upton, Long Island, New York
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  Over the past several years Advanced Energy Systems and BNL have been collaborating on the development and testing of a fully superconducting photocathode electron gun. Over the past year we have begun to realize significant results which have been published elsewhere.* This paper will review the RF design of the gun under test and present results of its performance under various operating conditions. Results for cavity quality factor will be presented for various operating temperatures and cavity field gradients. We will discuss various methods of determining the cavity fields and the extent of agreement between them. We will also discuss future plans for testing using this gun.

*Photoemission studies on BNL/AES all niobium, Superconducting RF injector, T. Rao, these proceedings.

 
 
TPPE063 Improved Electron Yield and Spin-Polarization from III-V Photocathodes Via Bias Enhanced Carrier Drift cathode, polarization, vacuum, laser 3603
 
  • G.A. Mulhollan, J.C.B. Bierman
    Saxet, Austin, Texas
  • A. Brachmann, J.E. Clendenin, E.G. Garwin, R.E. Kirby, D.-A.L. Luh, T.V.M. Maruyama
    SLAC, Menlo Park, California
  • R.X.P. Prepost
    UW-Madison/PD, Madison, Wisconsin
  Funding: Work at Saxet Surface Science, SLAC and the University of Wisconson is supported by the following U.S. DOE grants respectively: DE-FG02-04ER86231, DE-AC02-76SF00515 and DE-AC02-76ER00881.

Spin-polarized electrons are commonly used in high energy physics. Future work will benefit from greater polarization. Polarizations approaching 90% have been achieved at the expense of yield. The primary paths to higher polarization are material design and electron transport. Our work addresses the latter. Photoexcited electrons may be preferentially emitted or suppressed by an electric field applied across the active region. We are tuning this forward bias for maximum polarization and yield, together with other parameters, e.g., doping profile Preliminary measurements have been carried out on bulk GaAs. As expected, the yield change far from the bandgap is quite large. The bias is applied to the bottom (non-activated) side of the cathode so that the accelerating potential as measured with respect to the ground potential chamber walls is unchanged for different front-to-back cathode bias values. For a bias which enhances emission, the yield nearly doubles. For a bias which diminishes emission, the yield is approximately one half of the zero bias case. The size of the bias to cause an appreciable effect is rather small reflecting the low drift kinetic energy in the zero bias case.

 
 
TPPE064 Space-Charge Effects Near a Cathode cathode, simulation, space-charge, laser 3629
 
  • V. Gorgadze
    UCB, Berkeley, California
  • J.S. Wurtele
    LBNL, Berkeley, California
  Funding: This work was supported by the Director, Office of Science of the U.S. DOE under Contract No. DE-AC03-76SF00098.

RF photocathode guns are excellent sources of high brightness electron bunches. In the limit of high-current short bunches the electron are complicated space-charge fields. To mitigate space charge effect downstream of the gun it is often desirable to produce electorn bunches with uniform distribution. Our goal is to understand to what extent the non-uniformity of the laser pulse intensity is responsible for a non-uniform electron distribution and to what extent this is due to the electron beam dynamics near to the cathode. We investigate these effects with particle-in-cell simulations and simple theory. These studies are focused on the regime where the peak current as well as the temporal current profile are influenced by the self-fields of the bunch. The simulation code XOOPIC has been employed. The critical current limitation for virtual cathode formation and current density profile at the exit of the injector have been found.

 
 
TPPE065 Calculating of Coupling Factor of Microwave Electron Gun coupling, simulation, gun, cathode 3656
 
  • X. Bian, H. Chen, S. Zheng
    TUB, Beijing
  • D. Li
    LBNL, Berkeley, California
  To design the coupler of a designing microwave electron gun, we use the "energy method" proposed by Derun Li, et al. The intrinsic Q of the electron gun cavity is very high: about 20000. The method calculates the intrinsic and external Q values of a cavity coupled to a waveguide using MAFIA code in time domain. The comparisons between simulation and experimental results are given for a set of different coupling iris apertures and height. The result shows that "energy method" works efficiently for high Q cavities.  
 
TPPE066 Geometry Optimization of DC/RF Photoelectron Gun gun, cathode, simulation, emittance 3679
 
  • P. Chen, R. Yi, D. Yu
    DULY Research Inc., Rancho Palos Verdes, California
  Funding: *Work supported by DOE SBIR Grant No. DE-FG02-03ER83878.

Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.

 
 
TPPP009 Precise Energy Measurements in Experiments on VEPP-4M Collider polarization, photon, energy-calibration, resonance 1138
 
  • A. Bogomyagkov, V.E. Blinov, V.P. Cherepanov, V. Kiselev, E. Levichev, S.I. Mishnev, N.Yu. Muchnoi, S.A. Nikitin, I.B. Nikolaev, D.M. Nikolenko, A.G. Shamov, E. Shubin, A.N. Skrinsky, Yu.A. Tikhonov, D.K. Toporkov, G.M. Tumaikin
    BINP SB RAS, Novosibirsk
  The series of experiments on mass measurements of J/Psi, Psi', X and D mesons have been done on VEPP4-M collider. The accuracy of obtained masses values for psi mesons exceeded world value more than 3 times. Experiment on mass measuremnt of tau lepton is in progress. All these experiments require absolute energy calibration of the beams. Resonant depolarization technique has been used for most accurate energy measurement with relative accuracy of 1 ppm (10-6). Compton backscattering effect is used in developing facility for fast energy measurements. Moller scattering of the beam on polarized gas jet target has been used for beam polarization measurements.  
 
TPPP010 Photon-Nucleon Collider Based on LHC and CLIC luminosity, proton, collider, photon 1207
 
  • H. Aksakal, A.K. Ciftci
    Ankara University, Faculty of Sciences, Tandogan/Ankara
  • D. Schulte, F. Zimmermann
    CERN, Geneva
  We describe the scheme of a photon-nucleon collider where high-energy photons generated by Compton back-scattering off a CLIC electron beam, at either 75 GeV or 1.5 TeV, are collided with protons or ions stored in the LHC. Different design constraints for such a collider are discussed and the achievable luminosity performance is estimated.  
 
TPPP011 Investigations of Injection Orbits at CESR Based on Turn-By-Turn BPM Measurements injection, positron, betatron, optics 1228
 
  • M.G. Billing, J.A. Crittenden, M.A. Palmer
    Cornell University, Department of Physics, Ithaca, New York
  Funding: National Science Foundation.

Development of a data acquisition permitting turn-by-turn orbit measurements has been employed at CESR to study the optics of the injected electron beam. An optimization algorithm uses these measurements to determine the effective lattice functions describing the behavior of the injected electrons. We present comparisons of these measurements to tracking calculations of injection acceptance envelopes which account for the parasitic beam-beam interactions with the stored positron beam.

 
 
TPPP012 A Study of the Effect of Beam-Beam Interactions on CESR Optics positron, quadrupole, lattice, betatron 1275
 
  • J.A. Crittenden, M.G. Billing
    Cornell University, Department of Physics, Ithaca, New York
  • D. L. Rubin
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  Funding: National Science Foundation.

The CESR storage ring facility has begun operation in an energy region which allows high-statistics investigation of charm-quark bound states. Experience during the first year has shown that the effects of parasitic crossings in the pretzel orbits present an important factor in injection efficiency, in the beam lifetime and stored current limits. We compare the results of beam dynamics and tracking calculations which quantify the effects of these parasitic crossings on optics and dynamic aperture for the injected and stored trajectories to observations of beam behavior.

 
 
TPPP015 ELIC at CEBAF ion, collider, luminosity, emittance 1437
 
  • Y.S. Derbenev, S.A. Bogacz, J.R. Delayen, J.M. Grames, A. Hutton, G.A. Krafft, R. Li, L. Merminga, M. Poelker, B.C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
  • C. Montag
    BNL, Upton, Long Island, New York
  Funding: Work supported by DOE Contract DE-AC05-84ER40150.

We report on the progress of the conceptual development of the energy recovering linac (ERL)-based Electron-Light Ion Collider (ELIC) at CEBAF that is envisioned to reach luminosity level of 1033-1035 /cm2s with both beams polarized to perform a new class of experiments in fundamental nuclear physics. Four interaction points with all light ion species longitudinally or transversally polarized and fast flipping of the spin for all beams are planned. The unusually high luminosity concept is based on the use of the ERL and circulator ring-based electron cooling and crab crossing colliding beams. Our recent studies concentrate on the design of low beta interaction points with crab-crossing colliding beams, the exploration on raising the polarized electron injector current to the level of 3-30 mA with the use of electron circulator-collider ring, forming a concept of stacking and cooling of the ion beams, specifications of the electron cooling facility, and studies of beam-beam interaction and intra-beam scattering.

 
 
TPPP019 Collective Effects in Lepton Ring of eRHIC lepton, impedance, ion, positron 1628
 
  • D. Wang, M. Farkhondeh, C. Tschalaer, F. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • M. Blaskiewicz, Y. Luo, L. Wang
    BNL, Upton, Long Island, New York
  Funding: Department of Energy.

The eRHIC is a new generation lepton-hadron collider undergoing design studies by a collaboration of BNL, MIT, DESY and BINP. The collider complex will consist of a hadron machine that is mainly the existing RHIC with necessary upgrades, and a new lepton machine that can provide intense, highly polarized electron and positron beams at energy of 5-10 GeV. The ring-ring option of eRHIC is to build a 5-10 GeV electron ring with a injector chain. In this paper the beam lifetime of lepton beams is calculated.

 
 
TPPP022 The eRHIC Ring-Ring Collider Design ion, polarization, proton, luminosity 1766
 
  • F. Wang, M. Farkhondeh, W.A. Franklin, W. Graves, R. Milner, C. Tschalaer, D. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • D.P. Barber
    DESY, Hamburg
  • J. Beebe-Wang, A. Deshpande, V. Litvinenko, W.W. MacKay, C. Montag, S. Ozaki, B. Parker, S. Peggs, V. Ptitsyn, T. Roser, S. Tepikian, D. Trbojevic
    BNL, Upton, Long Island, New York
  The eRHIC ring-ring collider is the main design option of the future lepton-ion collider at Brookhaven National Laboratory. We report the revisions of the ring-ring collider design features to the baseline design presented in the eRHIC Zeroth Design Report (ZDR). These revisions have been made during the past year. They include changes of the interaction region which are required from the modifications in the design of the main detector. They also include changes in the lepton storage ring for high current operations as a result of better understandings of beam-beam interaction effects. The updated collider luminosity and beam parameters also take into account a more accurate picture of current and future operational aspects of RHIC.  
 
TPPP023 Simulation of PEP-II Accelerator Backgrounds Using TURTLE scattering, background, collimation, betatron 1835
 
  • R.J. Barlow, H. Fieguth
    SLAC, Menlo Park, California
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • S.A. Majewski
    Stanford University, Stanford, Califormia
  • P. Roudeau, A. Stocchi
    LAL, Orsay
  We present studies of accelerator-induced backgrounds in the BaBar detector at the SLAC B-Factory, carried out using a modified version ofthe DECAY TURTLE simulation package. Lost-particle backgrounds in PEP-II are dominated by a combination of beam-gas bremstrahlung, beam-gas Coulomb scattering, radiative-Bhabha events and beam-beam blow-up. The radiation damage and detector occupancy caused by the associated electromagnetic shower debris can limit the usable luminosity. In order to understand and mitigate such backgrounds, we have performed a full programme of beam-gas and luminosity-background simulations, that include the effects of the detector solenoidal field, detailed modelling of limiting apertures in both collider rings, and optimization of the betatron collimation scheme in the presence of large transverse tails.  
 
TPPP024 Experimental Study of Crossing-Angle and Parasitic-Crossing Effects at the PEP-II e+e- Collider luminosity, simulation, optics, quadrupole 1874
 
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • Y. Cai, J. Seeman, M.K. Sullivan
    SLAC, Menlo Park, California
  • I.V. Narsky
    CALTECH, Pasadena, California
  In a series of dedicated accelerator experiments, we have measured the dependence of the PEP-II luminosity performance on small horizontal crossing angles and on the horizontal separation at the first parasitic crossing. The experiment was carried out by varying the IP angle of one of the beams in two different bunch patterns, one with and one without parasitic crossings. The experimental measurements show satisfactory agreement with three-dimensional beam-beam simulations.  
 
TPPP025 Modeling Lost-Particle Accelerator Backgrounds in PEP-II Using LPTURTLE scattering, background, vacuum, optics 1889
 
  • H. Fieguth, R.J. Barlow
    SLAC, Menlo Park, California
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  Funding: Department of Energy Contract DE-AC02-76SF00515.

Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE a modified version of Decay TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar.

 
 
TPPP026 Bunch-Length Measurements in PEP-II single-bunch, synchrotron, positron, luminosity 1934
 
  • A.S. Fisher, A. Novokhatski, J.L. Turner, U. Wienands, G. Yocky
    SLAC, Menlo Park, California
  • R. Holtzapple
    Alfred University, Alfred, New York
  Funding: Supported by U.S. Department of Energy contract DE-AC03-76SF00515.

We measured the lengths of colliding e+e- bunches in the PEP-II B Factory at SLAC using various techniques. First, at several RF voltages and with both single-bunch and multibunch beams, a synchroscan streak camera measured synchrotron emission through a narrow blue filter. With 3.8 MV of RF, the length of a single positron bunch was 12 mm at low current, rising to 13 mm at 1.5 mA and 14.8 mm at 3 mA. The electrons measured 12.2 mm with little current dependence. Both are longer than the expected low-current value of 10 mm (e+) and 11 mm (e-), derived from the energy spread and the measured synchrotron tune. We also determined the length from measurements between 2 and 13 GHz of the bunch spectrum on a BPM button. After correcting for the frequency dependence of cable attenuation, we then fit the measured spectrum to that of a Gaussian bunch. With 3.8 MV, the positrons measurement gave 13.2 mm at 1.5 mA/bunch in a full ring, in agreement with the streak camera, but we found 11.4 mm for the electrons at 16.7 MV and 1 mA/bunch, lower than the streak measurement.

 
 
TPPP027 Single-Bunch Tune and Beam Size Measurements Along Bunch Trains in PEP-II luminosity, single-bunch, positron, feedback 2006
 
  • R. Holtzapple
    Alfred University, Alfred, New York
  • D.D. Dujmic, A.S. Fisher
    SLAC, Menlo Park, California
  By scanning a gated camera and a gated tune monitor across the bunch pattern during normal colliding-bunch operation of PEP-II, the single-bunch tunes and beam sizes were measured simultaneously in the high and low energy storage rings of PEP-II. The measurements were made with 1561 colliding bunches in PEP-II, arranged in trains of 66 bunches, with each bunch in the train separated by 4.2 ns. The tune and beam size measurements were correlated with the current, luminosity, and specific luminosity of the bunch. The results show a vertical tune shift at the start and end of the mini-trains, a luminosity droop along the mini-train, and specific luminosity drop in the first and last bunches of the train, since they experience a different parasitic crossing on either side of the IP.  
 
TPPP035 Performance of the PEP-II B-Factory Collider at SLAC luminosity, injection, beam-beam-effects, positron 2369
 
  • J. Seeman, J. Browne, Y. Cai, S. Colocho, F.-J. Decker, M.H. Donald, S. Ecklund, R.A. Erickson, A.S. Fisher, J.D. Fox, S.A. Heifets, R.H. Iverson, A. Kulikov, N. Li, A. Novokhatski, M.C. Ross, P. Schuh, T.J. Smith, K.G. Sonnad, M. Stanek, M.K. Sullivan, P. Tenenbaum, D. Teytelman, J.L. Turner, D. Van Winkle, M. Weaver, U. Wienands, M. Woodley, Y.T. Yan, G. Yocky
    SLAC, Menlo Park, California
  • M.E. Biagini
    INFN/LNF, Frascati (Roma)
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • C. Steier, A. Wolski
    LBNL, Berkeley, California
  • G. Wormser
    IPN, Orsay
  Funding: Work supported by DOE contract DE-AC02-76SF00515.

For the PEP-II Operation Staff: PEP-II is an asymmetric e+e- collider operating at the Upsilon 4S and has recently set several performance records. The luminosity has reached 9.2 x 1033/cm2/s. PEP-II has delivered an integrated luminosity of 710/pb in one day. It operates in continuous injection mode for both beams boosting the integrated luminosity. The peak positron current has reached 2.55 A in 1588 bunches. The total integrated luminosity since turn on in 1999 has reached 256/fb. This paper reviews the present performance issues of PEP-II and also the planned increase of luminosity in the near future to over 2 x 1034/cm2/s. Upgrade details and plans are discussed.

 
 
TPPP043 ERL Based Electron-Ion Collider eRHIC proton, luminosity, ion, collider 2768
 
  • V. Litvinenko, L. Ahrens, M. Bai, J. Beebe-Wang, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, R. Calaga, X.Y. Chang, A.V. Fedotov, W. Fischer, D. Kayran, J. Kewisch, W.W. MacKay, C. Montag, B. Parker, S. Peggs, V. Ptitsyn, T. Roser, A. Ruggiero, T. Satogata, B. Surrow, S. Tepikian, D. Trbojevic, V. Yakimenko, S.Y. Zhang
    BNL, Upton, Long Island, New York
  • A. Deshpande
    Stony Brook University, Stony Brook
  • M. Farkhondeh
    MIT, Middleton, Massachusetts
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy.

We present the designs of a future polarized electron-hadron collider, eRHIC* based on a high current super-conducting energy-recovery linac (ERL) with energy of electrons up to 20 GeV. We plan to operate eRHIC in both dedicated (electron-hadrons only) and parallel(with the main hadron-hadron collisions) modes. The eRHIC has very large tunability range of c.m. energies while maintaining very high luminosity up to 1034 cm-2 s-1 per nucleon. Two of the most attractive features of this scheme are full spin transparency of the ERL at all operational energies and the capability to support up to four interaction points. We present two main layouts of the eRHIC, the expected beam and luminosity parameter, and discuss the potential limitation of its performance.

*http://www.agsrhichome.bnl.gov/eRHIC/, Appendix A: Linac-Ring Option.

 
 
TPPP044 Interaction Region Design for the Electron-Light Ion Collider ELIC synchrotron, synchrotron-radiation, quadrupole, radiation 2824
 
  • C. Montag
    BNL, Upton, Long Island, New York
  • S.A. Bogacz, Y.S. Derbenev, L. Merminga
    Jefferson Lab, Newport News, Virginia
  Funding: Work performed under the auspices of the US Department of Energy.

The Electron-Light Ion Collider ELIC proposed by Jefferson Lab aims at very high luminosities for collisions of 150 GeV protons on 7 GeV electrons. To achieve these high luminosities, very strong low-beta focusing of low-emittance beams is required. Taking advantage of the unequal design proton beam emittances in the two transverse planes, an interaction region design based on superconducting quadrupole doublets has been deveoped. Compared with the original design, this scheme provides larger beam apertures at lower magnetic fields, while potentially doubling the luminosity.

 
 
TPPP045 Interaction Region Design for the Electron-Ion Collider eRHIC radiation, interaction-region, synchrotron, synchrotron-radiation 2893
 
  • C. Montag, B. Parker, S. Tepikian
    BNL, Upton, Long Island, New York
  • D. Wang
    MIT, Middleton, Massachusetts
  Funding: Work performed under the auspices of the U.S. Department of Energy.

To facilitate the study of collisions between 10 GeV polarized electrons and 100 GeV/u heavy ions or 250 GeV polarized protons at high luminosities, adding a 10 GeV electron storage ring to the existing RHIC complex has been proposed. The interaction region of this electron-ion collider eRHIC has to provide the required low-beta focusing, while simultaneously accomodating the synchrotron radiation fan generated by beam separation close to the interaction point, which is particularly challenging. The latest design status of the eRHIC interaction region is presented.

 
 
TPPP049 eRHIC Detector Design Studies - Implications and Constraints on the ep(A) Interaction-Region Design interaction-region, proton, scattering, luminosity 3043
 
  • B. Surrow
    BNL, Upton, Long Island, New York
  • A. Deshpande
    Stony Brook University, Stony Brook
  • J. Pasukonis
    MIT, Cambridge, Massachusetts
  An electron-proton/ion collider facility (eRHIC) is under consideration at Brookhaven National Laboratory. This high energy, high intensity polarized electron/positron beam facility to collide with the existing RHIC heavy ion and polarized proton beam would significantly enhance the exploration of fundamental aspects of Quantum Chromodynamics (QCD), the underlying quantum field theory of strong interactions. The design of a new optimized detector is closely coupled to the design of the interaction region and thus to the machine development work in general. A GEANT-based detector simulation framework has been developed to study various processes at eRHIC taking into consideration the impact of machine elements inside the detector volume and the synchrotron radiation fan generated by the electron/positron beam. The GEANT-based detector simulation framework called ELECTRA will be presented followed by a discussion of constraints and implications on the interaction region design.  
 
TPPT006 Development of RF Input Coupler with a Coaxial Line TiN-Coated Against Multipactoring vacuum, simulation, coupling, linac 1006
 
  • T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi
    KEK, Ibaraki
  In one of the normal-conducting RF cavities used in the KEKB operation, we observed an unexpected rise of the vacuum pressure at certain input-power levels with and without a beam current. From the simulation study, we identify the pressure rises as an effect of the multipactoring discharge in the coaxial line of the input coupler. According to the simulation results, we have decided to make TiN coating on the inner surface of the outer conductor to suppress the multipactoring. In this paper, the status of the development of the TiN-coated input coupler is reported including the recent results of the high-power tests.  
 
TPPT012 High Power Testing of Input Couplers for SuperKEKB vacuum, coupling, monitoring, positron 1294
 
  • H. Sakai, T. Abe, T. Kageyama, Y. Takeuchi
    KEK, Ibaraki
  In KEKB, 32 ARES cavities have been successfully operated to stably accelerate high-current electron and positron beams. Currently, each ARES cavity is fed with RF power (frequency = 509 MHz) of about 300 kW through an input coupler, which has a ceramic disk window at the coaxial line section following the doorknob transformer section with a capacitive iris at the rectangular waveguide entrance. For SuperKEKB, which is a challenging project to boost the luminosity frontier beyond 1035 cm-2 s-1, the power capability of the input coupler needs to be upgraded to more than 900 kW, while the design power capability for KEKB is 400 kW. Recently, we have constructed a new test stand in order to simulate the actual operating condition for the input coupler to drive the ARES cavity with the maximum beam loading of 9.4 A expected for the SuperKEKB LER. In this article, the key features of the new test stand are described together with the recent results of high-power tests.  
 
TPPT017 Fabrication and Test of the Drift Tubes for PEFP 20 MeV DTL vacuum, alignment, proton, site 1552
 
  • Y.-H. Kim, Y.-S. Cho, H.-J. Kwon, M.-Y. Park
    KAERI, Daejon
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

Drift tubes of PEFP (Proton Engineering Frontier Project) 20MeV DTL contain electro-quadrupole magnet composed of commercial enamel wire cooled with water coolant. Those were fabricated through the process of brazing, assembling, electron-beam welding, and post-machining. During the e-beam welding, temperature increase was kept under 50 degree to protect the EQM wire from thermal damage. We performed several tests such as vacuum leak test, hydraulic test, and electrical test. EQM properties such as effective length, magnetic saturation, and offset between magnetic center and geometric center of DT were measured and recorded also.

 
 
TPPT019 Numerical Study of Coupling Slot Effects on Beam Dynamics in Industrial Accelerator Prototype coupling, quadrupole, simulation, injection 1622
 
  • V.V. Tarnetsky, V. Auslender, I. Makarov, M.A. Tiunov
    BINP SB RAS, Novosibirsk
  Funding: The work is supported by ISTC grant #2550.

At Budker INP, the work is in progress on development of high-efficiency, high-power electron accelerator named ILU-12. The accelerator has a modular structure and consists of a chain of accelerating cavities connected by on-axis coupling cavities with coupling slots in the common walls (the coupling constant is about 0.08). Main parameters of the accelerator are: operating frequency of 176 MHz, electron energy of up to 5 MeV, average beam power of 300 kW. The paper presents results of 3D electromagnetic field numerical simulations for ILU-12 accelerating structure with recovery of quadrupole filed disturbance because of large coupling holes. The results show that accelerating cell geometry chosen eliminates coupling slot influence on the beam dynamics.

 
 
TPPT021 Characterization and Tuning of a Microwave Gun Cavity gun, coupling, cathode, linac 1748
 
  • W.K. Lau, J. Chan, L.-H. Chang, C.W. Chen, H.Y. Chen, K.-T. Hsu, S.Y. Hsu, J.-Y. Hwang, Y.C. Wang, T.-T. Yang
    NSRRC, Hsinchu
  The SSRL rf gun cavity is electromagnetic structure with a half-cell at the cathode end and a full cell at the other end. Instead of coupling through beam pipe to produce the desired pi-mode for beam acceleration, these two cells are coupled through a frequency tunable side-coupled cell. Therefore, the strucuture is actually 3-cell cavity and the pi/2-mode will be used. This paper reports the characterization of these resonant modes at various side-coupled cell tuning conditions. And the behavior of this cavity will also be analytically examined.  
 
TPPT029 Fabrication of the Prototype 201.25 MHz Cavity for a Muon Ionization Cooling Experiment factory, collider, vacuum, instrumentation 2080
 
  • R.A. Rimmer, S. Manning, R. Manus, H.L. Phillips, M. Stirbet, K. Worland, G. Wu
    Jefferson Lab, Newport News, Virginia
  • R.A. Hafley, R.E. Martin, K.M. Taminger
    NASA Langley, Hampton, Virginia
  • D. Li, R.A. MacGill, J.W.  Staples, S.P. Virostek, M.S. Zisman
    LBNL, Berkeley, California
  • M. Reep, D.J. Summers
    UMiss, University, Mississippi
  Funding: This manuscript has been authored by SURA, Inc. under DoE Contract No. DE-AC05-84ER-40150, LBNL contract No. DE-AC03-76SF00098 and NASA contract IA1-533 subagreement #2

We describe the fabrication and assembly of the first prototype 201.25 MHz copper cavity for the muon ionization cooling experiment (MICE). This cavity was developed by the US MUCOOL collaboration and will be tested in the new Muon Test Area at Fermilab. We outline the component and subassembly fabrication steps and the various metal forming and joining methods used to produce the final cavity shape. These include spinning, brazing, TIG welding, electron beam welding, electron beam annealing and deep drawing. Assembly of the loop power coupler will also be described. Final acceptance test results are included. Some of the methods developed for this cavity are novel and offer significant cost savings compared to conventional construction methods.

 
 
TPPT033 Simulations Using the VORPAL Code of Electron Impact Ionization Effects in Waveguide Breakdown Processes simulation, ion, plasma, space-charge 2298
 
  • P. Stoltz, J.R. Cary, P. Messmer, C. Nieter
    Tech-X, Boulder, Colorado
  Funding: Supported by Department of Energy SBIR Grant No. DE-FG03-02ER83554.

We present results of three-dimensional simulations using the VORPAL code of power absorbtion by stray electrons in X-band waveguides. These simulations include field emission from the waveguide surfaces, impact ionization of background gas, and secondary emission from the walls. We discuss the algorithms used for each of these electron effects. We show the power abosrbed as a function of background gas density. Finally, we present scaling results for running these simulations on Linux Clusters.

 
 
TPPT037 A Coaxial Subharmonic Cavity Design for Direct Injection at the Advanced Photon Source booster, linac, injection, higher-order-mode 2497
 
  • G.J. Waldschmidt, A. Nassiri
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

Coaxial subharmonic cavity designs are being investigated at the Advanced Photon Source to improve injector reliability by injecting beam directly from the linac to the booster in storage ring top-up mode. The subharmonic system must operate jointly with the present 352-MHz booster to accelerate the beam to 7 GeV with minimal beam degradation. Design considerations must be made to ensure that bunch purity is maintained and that a large percentage of the linac macropulse is captured. An analysis of rf cavity designs using electromagnetic simulation software has been conducted at 58 MHz and 117 MHz. The final design evaluates the total power loss, field uniformity, and peak surface fields to achieve the required gap voltage.

 
 
TPPT051 High Power Coupler for the TESLA Superstructure Cavities vacuum, insertion, coupling, SNS 3141
 
  • Q.S. Shu, G. Cheng, J. T. Susta
    AMAC, Newport News, Virginia
  • S.J. Einarson
    CPI/BMD, Beverley, Massachusetts
  • T. Garvey
    LAL, Orsay
  • W.-D. Müller, D. Proch
    DESY, Hamburg
  • T.A. Treado
    CPI, Beverley, Massachusetts
  Funding: U.S. Department of Energy Grant No. DE-FG02-00ER86102.

More and more accelerators are built with superconducting cavities operating at cryogenic temperatures, and the probability of a ceramic window failure presents increasing problems because of the resulting contamination of the cavities surfaces and the resulting accelerating electric field degradation. A cost effective design and fabrication method for the TESLA cavities has been developed in the framework of a DOE STTR grant. This new design replaces the present TESLA cylindrical ceramic windows with two planar disc windows separated by a vacuum space and is optimized for RF input power, vacuum characteristics, and thermal properties. This novel coupler will reduce the costs of fabrication and improve the RF performance of the coupler, the vacuum between the two windows, and the cleaning procedure. Two couplers with this design have been fabricated and are presently being conditioned for testing at DESY, Germany, and LAL, France, on the RF high power testing stand and on a test cryomodule.

 
 
TPPT066 Successful Operation of the 500 MHz SRF Module at TLS synchrotron, photon, klystron, injection 3706
 
  • C. Wang, L.-H. Chang, S.-S. Chang, C.-T. Chen, F.-T. Chung, F.-Z. Hsiao, G.-Y. Hsiung, K.-T. Hsu, C.-C. Kuo, H.C. Li, M.-C. Lin, R.J. Lin, Y.K. Lin, G.-H. Luo, M.H. Tsai, J.Y. Yang, T.-T. Yang, M.-S. Yeh
    NSRRC, Hsinchu
  A superconducting radio frequency (SRF) cavity of CESR-III design was installed sucessfully in the electron storage ring at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. The project goals are to double the photon flux by raising the electron beam current and to increase the beam stability by taking advantage of the well-damped high-order modes of SRF cavity. Nowadays, SRF cavity has become the key technology for new synchrotron light sources under construction or planning worldwide. The first operational experience of the SRF cavity at the NSRRC will be presented.  
 
TPPT072 Effects of Electric and Magnetic Fields on the Performance of a Superconducting Cavity feedback, vacuum, superconductivity, coupling 3874
 
  • G. Ciovati, P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • J.S. Sekutowicz, W. Singer
    DESY, Hamburg
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

A special two-cell cavity was designed to obtain surface field distributions suitable for investigation of electric and magnetic field effects on cavity performance. The cavity design and preliminary results were presented in a previous contribution. The bulk niobium cavity was heat-treated in a vacuum furnace at 1250C to improve the thermal conductivity. Three seamless hydroformed NbCu cavities of the same design were fabricated to investigate the role of the electron beam welds located in high field areas.

 
 
TPPT075 Influence of Ta Content in High Purity Niobium on Cavity Performance vacuum, coupling, linac, SNS 3955
 
  • P. Kneisel, G. Ciovati, G. Myneni
    Jefferson Lab, Newport News, Virginia
  • T. Carneiro
    Reference Metals, Bridgeville, Pennsylvania
  • D. Proch, W. Singer, X. Singer
    DESY, Hamburg
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

In a previous paper* we have reported about initial tests of single cell 1500 MHz cavities made from high purity niobium with three different Ta contents of 160 ppm, ~600 ppm and ~1400 ppm. These cavities had been treated by buffered chemical polishing several times and 100 mm, 200 mm and 300 mm of material had been removed from the surfaces. This contribution reports about subsequent tests following post purification heat treatments with Ti and “in situ” baking. As a result, all cavities exhibited increased quench fields due to the improved thermal conductivity after the heat treatment. After the "in situ" baking at 120C for ~40 hrs the always present Q-drop at high fields disappeared and further improvements in accelerating gradient could be realized. Gradients as high as Eacc = 35 MV/m were achieved and there were no clear indications that the cavity performance was influenced by the Ta content in the material. A multi-cell cavity from the high Ta content material is being fabricated and results will be presented at this conference.

*P. Kneisel et al., Linac 2004.

 
 
TPPT076 Preliminary Results from Single Crystal and Very Large Crystal Niobium Cavities superconductivity, vacuum, coupling, SNS 3991
 
  • P. Kneisel, G. Ciovati, G. Myneni
    Jefferson Lab, Newport News, Virginia
  • T. Carneiro
    Reference Metals, Bridgeville, Pennsylvania
  • J.S. Sekutowicz
    DESY, Hamburg
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

We have fabricated and tested several single cell cavities using material from very large grain niobium ingots. In one case the central grain exceeded 7" in diameter and this was used for a 2 GHz cavity. This activity had a dual purpose: to investigate the influence of grain boundaries on the often observed Q-drop at gradients Eacc > 20 MV/m in the absence of field emission, and to study the possibility of using ingot material for cavity fabrication without going through the expensive process of sheet fabrication. The sheets for these cavities were cut from the ingot by wire electro-discharge machining (EDM) and subsequently formed into half–cells by deep drawing. The following fabrication steps were standard: machining of weld recesses, electron beam welding of beam pipes onto the half cells and final equator weld to join both half cell/beam pipe subunits.The cavities showed heavy Q–disease caused by the EDM; after hydrogen degassing at 800C for 3 hrs in UHV the cavities showed promising results, however, a Q-drop above Eacc ~ 20 MV/m was still present. Testing of the cavities is still ongoing – so far accelerating gradients of 30 MV/m have been achieved.

 
 
TPPT084 Surface Study of Nb/Cu Films for Cavity Deposition by ECR Plasma ion, vacuum, superconductivity, plasma 4153
 
  • A.T. Wu, R.C. Ike, H.L. Phillips, A-M. Valente, H. Wang, G. Wu
    Jefferson Lab, Newport News, Virginia
  Funding: This manuscript has been authorized by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy.

Deposition of thin niobium (Nb) films on copper (Cu) cavities, using an electron cyclotron resonance (ECR) plasma appears to be an attractive alternative technique for fabricating superconducting radio frequency cavities to be used in particle accelerators. The performance of these Nb/Cu cavities is expected to depend on the surface characteristics of the Nb films. In this paper, we report on an investigation of the influence of deposition energy on surface morphology, microstructure, and chemical composition of Nb films deposited on small Cu disks employing a metallographic optical microscope, a 3-D profilometer, a scanning electron microscope, and a dynamic secondary ion mass spectrometer. The results will be compared with those obtained on Nb surfaces treated by buffered chemical polishing, electropolishing, and buffered electropolishing. Possible implications from this study for Nb deposition on real Cu cavities will be discussed.

 
 
TPPT098 VORPAL as a Tool for Three-Dimensional Simulations of Multipacting in Superconducting RF Cavities simulation, plasma, radio-frequency, resonance 4332
 
  • C. Nieter, J.R. Cary, P. Stoltz
    Tech-X, Boulder, Colorado
  • G.R. Werner
    CIPS, Boulder, Colorado
  Considerable resources are required to run three dimensional simulations of multipacting in superconducting rf cavities. Three dimensional simulations are needed to understand the possible roles of non-axisymmetric features such as the power couplers. Such simulations require the ability to run in parallel. We consider the versatile plasma simulation code VORPAL* as a possible platform to study such effects. VORPAL has a general 3D domain decomposition and can run in any physical dimension. VORPAL uses the CMEE library** to model the secondary emission of electrons from metal surfaces. We will present a three dimensional simulation of a simple pillbox rf cavity to demonstrate the potential of VORPAL to be a major simulation tool for superconducting rf cavities.

*C. Nieter and J.R. Cary, J. Comp. Phys. 196 (2004), p. 448. **P.H. Stoltz, ICFA electron cloud work shop, Napa, CA (2004).

 
 
TPPT099 Prototype Superconducting Triple-Spoke Cavity for Beta = 0.63 linac, vacuum, superconductivity, coupling 4338
 
  • K.W. Shepard, Z.A. Conway, J.D. Fuerst, M. Kedzie, M.P. Kelly
    ANL, Argonne, Illinois
  Funding: This work was supported by the U.S. Department of Energy under contract no. W-31109ENG_38.

This paper reports the development status of a 345 MHz, three-spoke-loaded, TEM-class superconducting cavity with a transit-time factor peaked at beta = v/c = 0.62. The cavity has a 4 cm diameter beam aperture, a transverse diameter of 45.8 cm, and an effective (interior) length of 85 cm. The cavity is the second of two three-spoke loaded cavities being developed for the RIA driver linac and other high-intensity ion linac applications. Construction of a prototype niobium cavity has been completed and the cavity has been chemically processed. Results of initial cold tests will be discussed

 
 
TOPA001 Mono Energetic Beams from Laser Plasma Interactions laser, plasma, injection, simulation 69
 
  • C.G.R. Geddes, E. Esarey, W. Leemans, C.B. Schroeder, C. Toth
    LBNL, Berkeley, California
  • J.R. Cary, C. Nieter
    Tech-X, Boulder, Colorado
  • J. Van Tilborg
    TUE, Eindhoven
  Funding: Supported by U.S. Dept. of Energy contracts DE-AC03-76SF00098, DE-FG03-95ER40926, DE-FG02-01ER41178, DE-FG02-03ER83857, SciDAC, and NSF 0113907. C. Geddes is also supported by the Hertz foundation.

A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100% electron energy spread. In the present experiments on the L’OASIS laser,* the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing >200pC charge above 80 MeV and with normalized emittance estimated at < 2 pi -mm-mrad were produced.** Data and simulations (VORPAL***) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4TW was guided without trapping, potentially providing a platform for controlled injection. The plasma channel technique forms the basis of a new class of accelerators, with high gradients and high beam quality.

*W.P. Leemans et al., Phys. Plasmas 5, 1615-23 (1998). **C.G.R. Geddes et al., Nature 431, 538-41 (2004). ***C. Nieter et al., J. Comp. Phys. 196, 448-73 (2004).

 
 
TOPA005 Left-Handed Metamaterials Studies and their Application to Accelerator Physics radiation, dipole, plasma, diagnostics 458
 
  • S.P. Antipov, W. Liu, J.G. Power
    ANL, Argonne, Illinois
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois
  Funding: DOE grant NSF grant

Recently, there has been a growing interest in applying artificial materials, known as Left-Handed Metamaterials (LHM), to accelerator physics. These materials have both negative permittivity and permeability and therefore possess several unusual properties: the index of refraction is negative and the direction of the group velocity is antiparallel to the direction of the phase velocity (along k). These properties lead to a reverse Cherenkov effect, which has potential beam diagnostic applications, in addition to accelerator applications. Several LHM devices with different configurations are being experimentally and theoretically studied at Argonne. In this paper, we describe permittivity and permeability retrieval techniques that we have developed and applied to these devices. We have also investigated the possibility of building a Cherenkov detector based on LHM and propose an experiment to observe the reverse radiation generated by an electron beam passing through a LHM. The potential advantage of a LHM detector is that the radiation in this case is emitted in the direction reversed to the direction of the beam, so it could be easier to get a clean measurement.

 
 
TOPA006 High Energy Gain IFEL at UCLA Neptune Laboratory laser, undulator, acceleration, simulation 500
 
  • P. Musumeci, S. Boucher, C.E. Clayton, A. Doyuran, R.J. England, C. Joshi, C. Pellegrini, J.E. Ralph, J.B. Rosenzweig, C. Sung, S. Tochitsky, G. Travish, R.B. Yoder
    UCLA, Los Angeles, California
  • S.V. Tolmachev, A. Varfolomeev, A. Varfolomeev, T.V. Yarovoi
    RRC Kurchatov Institute, Moscow
  We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 mkm laser with power larger than 400 GW. The Rayleigh range of the laser, ~ 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the first half of the undulator at a gradient of 70 MeV/m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator.  
 
TOPA007 Proton Acceleration and High-Energy Density Physics from Laser Foil Interactions proton, target, acceleration, ion 573
 
  • P.A. Norreys
    CCLRC/RAL, Chilton, Didcot, Oxon
  • F.N. Beg
    UCSD, La Jolla, California
  • A.E. Dangor, K.M. Krushelnick, M. Wei
    Imperial College of Science and Technology, Department of Physics, London
  • M. Tatarakis
    ,
  • M. Zepf
    Queen's University of Belfast, Belfast, Northern Ireland
  Intense laser plasma interactions have long been shown to be a source of very energetic ions - from the first experiments in the 1970's. However, there has been a recent revival of interest in the production of protons and ions from the such plasmas - primarily from the observation of collimated beams of protons and heavier ions which were observed at the rear thin foil targets irradiated by ultra-high intensity laser pulses (such that I > 1018 W/cm2). These ion beams have unique properties which may make them suitable for a variety of applications such as for probing high density plasmas, for fast ignition in inertial confinement fusion, as an ion source for subsequent acceleration stages in a particle accelerator or potentially for medical applications. Recent experimental results will be reviewed and the potential for such future applications will be highlighted.  
 
TOPA008 First Observation of Laser-Driven Acceleration of Relativistic Electrons in a Semi-Infinite Vacuum Space laser, acceleration, polarization, vacuum 650
 
  • T. Plettner, R.L. Byer, T.I. Smith
    Stanford University, Stanford, Califormia
  • E.R. Colby, B.M. Cowan, C.M.S. Sears, R. Siemann, J.E. Spencer
    SLAC, Menlo Park, California
  Funding: Department of Energy DE-FG03-97ER41043.

We have observed acceleration of relativistic electrons in vacuum driven by a linearly polarized laser beam incident on a thin gold-coated reflective boundary. The observed energy modulation effect follows all the characteristics expected for linear acceleration caused by a longitudinal electric field. As predicted by the Lawson-Woodward theorem the laser driven modulation only appears in the presence of the boundary. It shows a linear dependence with the strength of the electric field of the laser beam and also it is critically dependent on the laser polarization. Finally, it appears to follow the expected angular dependence of the inverse transition radiation process.

 
 
TOPA009 Photonic Band Gap Accelerator Demonstration at Ku-Band. linac, klystron, lattice, acceleration 656
 
  • E.I. Smirnova, L.M. Earley, R.L. Edwards
    LANL, Los Alamos, New Mexico
  • A.S. Kesar, I. Mastovsky, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts
  Funding: The research is supported by DOE High Energy Physics, Contract No. DE-FG02-91ER40648.

We report progress on the design and cold test of a metal Ku-band PBG accelerator structure. The 17.140 GHz 6-cell PBG accelerator structure with reduced long-range wakefields was designed for the experiment. The copper structure was electroformed and cold-tested. Tuning was performed through chemical etching of the rods. Final cold test measurements were found to be in very good agreement with the design. The structure will be installed on the beam line at the accelerator laboratory at Massachusetts Institute of Technology and will be powered with 3 MW of peak power from the Haimson 17.14 GHz klystron. Results of the design, fabrication, cold test and hot test on the Haimson accelerator will be presented.

 
 
TOPE001 Experience with the TTF-2 linac, beam-transport, quadrupole, undulator 1
 
  • L. Lilje
    DESY, Hamburg
  The TESLA Test Facility in its second phase (TTF-2) serves two main purposes: It is a testbed for the superconducting RF technology for the International Linear Collider as well as a user facility providing a VUV-FEL beam for experiments using synchrotron light. The presentation will review the progress on the superconducting RF technology. This includes tests on individual cavities as well as full accelerating modules. First experiences with the setup of TTF-2 will be presented. Among others, the measurements of higher order modes in the superconducting cavities are presented. Measurements of the beam properties will be shown.  
 
TOPD002 BEPCII -The Second Phase Construction of the Beijing Electron-Positron Collider luminosity, positron, vacuum, linac 131
 
  • C. Zhang, G. Pei
    IHEP Beijing, Beijing
  The Beijing Electron-Positron Collider (BEPC) was constructed for both high energy physics and synchrotron radiation researches. 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. As the second phase construction of the BEPC, the BEPCII has been approved with total budget of 640 million RMB. The construction was started in the beginning of 2004 and is scheduled to be completed 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 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., are being developed in order to achieve the target of the BEPCII.*

*Submitted on behalf of the BEPCII Team.

 
 
WOAA003 Progress and Plans for R&D and the Conceptual Design of the ILC Injector Systems positron, emittance, damping, undulator 315
 
  • S. Guiducci
    INFN/LNF, Frascati (Roma)
  The International Linear Collider Injector is a complex of different subsystems that are strictly correlated: positron source, polarized electron source, damping rings, bunch compressor and spin rotator. The choice of parameters of each subsystem has a strong influence on the others. A description of the critical items requiring further R&D in order to finalize the choice of the parameters needed for the Conceptual Design is given. The status and plans of the R&D in progress on these items at a global level are reported.  
 
WOAA005 Progress and Plans for R&D and the Conceptual Design of the ILC High Gradient Structures micro-particles, superconductivity, linear-collider, collider 461
 
  • H. Padamsee
    Cornell University, Ithaca, New York
  Gradients and Q’s in the dominant ILC candidate structure have shown steady improvement, reaching 35–40 MV/m in the last year by using the best techniques of electropolishing, high pressure rinsing and 120 C baking for 48 hours. Progress and plans for t his structure will be reviewed. Above 40 MV/m, the surface magnetic field encroaches the rf critical magnetic field, believed to fall between 1750 and 2000 Oe, depending on the theory. One way to circumvent the limit is to modify the cavity shape to reduc e the ratio of peak magnetic to accelerating field. Two candidate shapes are evolving, the Re-entrant shape and the Low-Loss shape. Although field emission is aggravated by higher electric fields, it does not present a brick wall limit because high pressu re rinsing at 100 bar eliminates microparticles which cause field emission. Fundamental and higher mode properties of these new shapes will be compared with the dominant ILC candidate. Results of single and multicell cavities will be presented. The record field in a single cell re-entrant cavity is now 46 MV/m corresponding to a surface magnetic field of 1750 Oe and a surface electric field of 101 MV/m.N  
 
WPAE013 Development of the Collimator System for the 3GEV Rapid Cycling Synchrotron radiation, shielding, vacuum, beam-losses 1365
 
  • K. Yamamoto
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • M. Kinsho
    Japan Atomic Energy Institute, Linac Laboratory, Tokai-Mura
  In order to localize the beam loss in the restricted area, the beam collimation system is prepared in the 3GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Complex (J-PARC) Project. The amount of the localized beam loss on the one collimator is estimated about 1.2kW, and that loss generates a large quantity of the secondary radiations. So the beam collimator must be designed that it is covered with enough shielding. We calculated the radiation level of the collimator and decided necessary shielding thickness. This result indicated that the residual dose rate at the outside surface of the shielding is mostly under 1mSv/h. We developed the remote cramp system and rad-hard components in order to reduce the radiation exposure during maintenance of the collimator. And also we coated Titanium Nitride (TiN) film on the inside surface of the vacuum chamber in order to reduce the secondary electron emission from the collimator and chamber surface. Now we investigate the possibility of another coating.  
 
WPAE025 Design for a 1.3 MW, 13 MeV Beam Dump for an Energy Recovery Linac vacuum, injection, linac, synchrotron 1877
 
  • C.K. Sinclair
    Cornell University, Department of Physics, Ithaca, New York
  • Y. He, C.H. Smith
    Cornell University, Ithaca, New York
  Funding: Work supported by Cornell University.

The electron beam exiting an Energy Recovery Linac (ERL) is dumped close to the injection energy. This energy is chosen as low as possible while allowing the beam quality specifications to be met. As ERLs are designed for high average beam current, beam dumps are required to handle high beam power at low energy. Low energy electrons have a short range in practical dump materials, requiring the beam size at the dump face be enlarged to give acceptable power densities and heat fluxes. Cornell University is developing a 100 mA average current ERL as a synchrotron radiation source. The 13 MeV optimum injection energy requires a 1.3 MW beam dump. We present a mature design for this dump, using an array of water-cooled extruded copper tubes. This array is mounted in the accelerator vacuum normal to the beam. Fatigue failure resulting from abrupt thermal cycles associated with beam trips is a potential failure mechanism. We report on designs for a 75 kW, 750 keV tube-cooled beryllium plate dump for electron gun testing, and a 500 kW, 5 to 15 MeV copper tube dump for use with the prototype injector under development. We expect to test the beryllium dump within a year, and the higher power copper dump within 2-1/2 years.

 
 
WPAE027 Magnetic Shielding of an Electron Beamline in a Hadron Accelerator Enclosure shielding, dipole, antiproton, quadrupole 1997
 
  • T.K. Kroc, C.W. Schmidt, A.V. Shemyakin
    Fermilab, Batavia, Illinois
  Funding: *Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

The Fermilab Electron Cooling Project requires the operation of a 4.35 MeV electron beam in the same enclosure that houses the 120 – 150 GeV Main Injector. Effective shielding of the magnetic fields from the ramped electrical buses and local static fields is necessary to maintain the high beam quality and recirculation efficiency required by the electron cooling system. This paper discusses the operational tolerances and the design of the beamline shielding, bus design, and bus shielding as well as experimental results from the prototype and final installation.

 
 
WPAE029 Tevatron Beam-beam Compensation Project Progress proton, antiproton, gun, emittance 2083
 
  • V.D. Shiltsev, R.J. Hively, V. Kamerdzhiev, A. Klebaner, G.F. Kuznetsov, A. Martinez, H. Pfeffer, G.W. Saewert, A. Semenov, D. Wolff, X. Zhang
    Fermilab, Batavia, Illinois
  • K. Bishofberger
    UCLA, Los Angeles, California
  • I. Bogdanov, E. Kashtanov, S. Kozub, V. Sytnik, L. Tkachenko
    IHEP Protvino, Protvino, Moscow Region
  • A.V. Kuzmin, M.A. Tiunov
    BINP SB RAS, Novosibirsk
  • F. Zimmermann
    CERN, Geneva
  Funding: Work supported by the Universities Research Assos., Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy.

The 2nd Tevatron electron lens (TEL2) is under the final phase of development and prepare for the installation in the Tevatron. In this report, we will describe the system and the main upgrades from the TEL1. We will also show the magnetic field measurement results, beam testing and plan for installation. The special operation consideration of the TEL2 under high radiation dose will also be discussed.

 
 
WPAE035 SNS Ring Injection Stripped Electron Collection: Design Analysis and Technical Issues SNS, dipole, injection, beam-losses 2384
 
  • Y.Y. Lee, G.J. Mahler, W. Meng, D. Raparia, L. Wang, J. Wei
    BNL, Upton, Long Island, New York
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

This paper describes the simulation studies on the motions of stripped electrons generated in the injection section of the Spallation Neutron Source (SNS) accumulator ring and the effective collection mechanism. Such studies are important for high intensity machines, in order to reduce beam loss and protect other components in the vicinity. The magnetic field is applied to guide electrons to a collector, which is located at the bottom of the beam chamber. Part of the study results with and without considering the interactions between electrons and materials are presented and discussed. The final engineering design of the electron collector (catcher) is also presented and described.

 
 
WPAP001 HELIOS, the Linac Injector of SOLEIL: Installation and First Results linac, gun, emittance, klystron 755
 
  • B. Pottin, R. Chaput, J.-P. Pollina, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  • D. Jousse, J.-L. Pastre, A.S. Setty
    THALES, Colombes
  Funding: SOLEIL

HELIOS is the Hundred MeV Electron Linac Injector Of SOLEIL the new French SR facility. The Linac is constructed by THALES as a “turn key” equipment on the basis of SOLEIL’s APD design. The Linac injector is composed of a triode gun (90 kV, 500 mA), a prebuncher (10 kV, 200 W), a buncher (SW, 15 MeV, 5 MW) focalised by a solenoid and two accelerating sections (TW, 2pi/3, 45 MeV, 12 MW) feeded by 2 klystrons (35 MW). The major Linac components have been previously tested at THALES factory and the installation on the site has begun from October 2004. After a brief description of the building construction, the tests of the Linac components and operating modes will be detailed. The commissioning with beam is planned on March; the results on beam qualities will be presented: energy spread, emittance, and beam dynamics along the Linac.

 
 
WPAP003 Emission Mechanisms in a Photocathode RF Gun emittance, cathode, laser, gun 856
 
  • J.H. Han, J.W. Baehr, H.-J. Grabosch, M. Krasilnikov, V. Miltchev, A. Oppelt, B. Petrosyan, S. Riemann, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • K. Floettmann, S. Schreiber
    DESY, Hamburg
  • M.V. Hartrott
    BESSY GmbH, Berlin
  • P. Michelato, L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI)
  • J.R. Roensch
    Uni HH, Hamburg
  In photocathode rf guns, emission mechanisms at the photocathode play a crucial role in the overall beam dynamics. A low bunch charge as well as a short Gaussian bunch profile allow us to study the beam dynamics depending on emission phase without space charge force. This paper presents experimental and simulation studies toward detailed understanding of the photo emission and secondary emission processes at the cathode.  
 
WPAP004 Dark Current and Multipacting in the Photocathode RF Guns at PITZ cathode, gun, laser, simulation 895
 
  • J.H. Han, J.W. Baehr, H.-J. Grabosch, M. Krasilnikov, V. Miltchev, A. Oppelt, B. Petrosyan, S. Riemann, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • K. Floettmann, S. Schreiber
    DESY, Hamburg
  • M.V. Hartrott
    BESSY GmbH, Berlin
  • P. Michelato, L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI)
  • J.R. Roensch
    Uni HH, Hamburg
  For photocathode rf guns, the amount of dark current depends on the cavity surface and the photocathodes. Smooth conditioning reduces the amount of dark current. Mechanical damages of the cathodes induce high dark current and chemical pollution changes emission properties of the cathode. Multipacting in the gun cavity changes the surface status of the cathodes and sometimes makes the gun operation impossible due to vacuum interlocks. In this paper, dark current and multipacting features of the rf gun are presented including experimental and simulation studies.  
 
WPAP005 Beam-Based Procedures for RF Guns laser, gun, cathode, alignment 967
 
  • M. Krasilnikov, J.W. Baehr, H.-J. Grabosch, J.H. Han, V. Miltchev, A. Oppelt, B. Petrosyan, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • M.V. Hartrott
    BESSY GmbH, Berlin
  A wide range of rf photo injector parameters has to be optimized in order to achieve an electron source performance as required for linac based high gain FELs. Some of the machine parameters can not be precisely controlled by direct measurements, whereas the tolerance on them is extremely tight. Therefore, this should be met with beam-based techniques. Procedures for beam-based alignment (BBA) of the laser on the photo cathode as well as solenoid alignment have been developed. They were applied at the Photo Injector Test facility at DESY Zeuthen (PITZ) and at the photo injector of the VUV-FEL at DESY Hamburg. A field balance of the accelerating mode in the 1 cell gun cavity is one of the key beam dynamics issues of the rf gun. Since no direct field measurement in the half and full cell of the cavity is available for the PITZ gun, a beam-based technique to determine the field balance has been proposed. A beam-based rf phase monitoring procedure has been developed as well.  
 
WPAP006 Recent Developments at PITZ laser, emittance, booster, gun 1012
 
  • M. Krasilnikov, K. Abrahamyan, G. Asova, J.W. Baehr, G. Dimitrov, U. Gensch, H.-J. Grabosch, J.H. Han, S. Khodyachykh, S. Liu, V. Miltchev, A. Oppelt, B. Petrosyan, S. Riemann, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • W. Ackermann, W.F.O. Müller, S. Schnepp, T. Weiland
    TEMF, Darmstadt
  • J.-P. Carneiro, K. Floettmann, S. Schreiber
    DESY, Hamburg
  • M.V. Hartrott, E. Jaeschke, D. Kraemer, D. Lipka, R. Richter
    BESSY GmbH, Berlin
  • P. Michelato, L. Monaco, C. Pagani, D. Sertore
    INFN/LASA, Segrate (MI)
  • J.R. Roensch, J. Rossbach
    Uni HH, Hamburg
  • W. Sandner, I. Will
    MBI, Berlin
  • I. Tsakov
    INRNE, Sofia
  The ability to produce high brightness electron beams as required for modern Free Electron Lasers (FELs) has been demonstrated during the first stage of the Photo Injector Test Facility at DESY Zeuthen (PITZ1). The electron source optimization at PITZ1 was successfully completed, resulting in the installation of the PITZ rf gun at the VUV-FEL (DESY, Hamburg). One of the main goals of the second stage of PITZ (PITZ2) is to apply higher gradients in the rf gun cavity in order to obtain smaller beam emittance by faster acceleration of the space charge dominated beams. In order to reach the required gradients a 10 MW klystron has to be installed and the gun cavity has to be conditioned for higher peak power. Another important goal of PITZ2 is a detailed study of the emittance conservation principle by using proper electron beam acceleration with a booster. Further photo injector optimization, including update of the photocathode laser and diagnostic tools, is foreseen as well. Recent progress on the PITZ developments will be reported.  
 
WPAP007 Status of the 3 Cell Superconducting RF Gun Project in Rossendorf gun, cathode, laser, pick-up 1081
 
  • R. Xiang, H. Buettig, P. Evtushenko, D. Janssen, U. Lehnert, P. Michel, K. Moeller, Ch. Schneider, R. Schurig, F. Staufenbiel, J. Teichert
    FZR, Dresden
  • T.  Kamps, D. Lipka
    BESSY GmbH, Berlin
  • W.-D. Lehmann
    IfE, Dresden
  • J. Stephan
    IKST, Drsden
  • V. Volkov
    BINP SB RAS, Novosibirsk
  • I. Will
    MBI, Berlin
  In the paper, we report on the status and progress of the superconducting rf gun project in Rossendorf. The gun is designed for cw operation mode with 1mA current and 10 MeV electron energy. The gun will be installed at the ELBE superconducting electron linear accelerator. It will have a 3 cell niobium cavity operating at 1.3 GHz. The cavity consists of three cells with TESLA geometry and a specially designed half-cell in which the photocathode will be placed. Two Nb cavities, with RRR 300 and 40 respectively, will be finished at the beginning of 2005. After delivery, the rf tests will be performed and the treatment of the cavities will be started. At the same time, the design of the cryostat is finished and the fabrication of its components is under way. Further activities are the design of the diagnostic beam line, the assembling of the new photocathode preparation system, and the upgrade of the 262 nm driver laser system.  
 
WPAP008 Simulation for a New Polarized Electron Injector (SPIN) for the S-DALINAC gun, simulation, cathode, vacuum 1117
 
  • B. Steiner, W.F.O. Müller, T. Weiland
    TEMF, Darmstadt
  • J. Enders, H.-D. Gräf, A. Richter, M. Roth
    TU Darmstadt, Darmstadt
  Funding: Work supported in part by DFG under contract SFB 634 and DESY, Hamburg.

The Superconducting DArmstädter LINear ACcelerator (S-DALINAC) is a 130 MeV recirculating electron accelerator serving several nuclear and radiation physics experiments. For future tasks, the 250 keV thermal electron source should be completed by a 100 keV polarized electron source. Therefore a new low energy injection concept for the S-DALINAC has to be designed. The main components of the injector are a polarized electron source, an alpha magnet, a Wien filter spin-rotator and a Mott polarimeter. In this paper we report over the first simulation and design results. For our simulations we used the TS2 and TS3 modules of the CST MAFIA (TM) programme which are PIC codes for two and three dimensions and the CST PARTICLE STUDIO (TM).

 
 
WPAP011 SPARC Working Point Optimization for a Bunch with Gaussian Temporal Profile emittance, radiation, simulation, undulator 1248
 
  • M. Boscolo, M. Ferrario, V. Fusco, M.  Migliorati
    INFN/LNF, Frascati (Roma)
  • S. Reiche
    UCLA, Los Angeles, California
  • C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma)
  We present the optimization of the working point for the SPARC photoinjector with a Gaussian temporal profile. The implications of a Gaussian temporal profile are discussed here for the standard working conditions and for the RF compressor case in comparison with the nominal working point performances of a 10ps flat top pulse with rise time of 1ps. Comparisons with the upgraded version of the HOMDYN code including arbitrary bunch temporal profiles are also reported. Advantages and drawbacks of the Gaussian and flat top pulse shapes are discussed. For the standard working point, it is shown that the two cases provide the same saturation length and average power, but the higher current in the beam core of the Gaussian pulse gives a higher peak radiation power. As the laser pulse shape could be Gaussian at the first stage of the SPARC operation, it is clear the importance of these simulation results.  
 
WPAP012 Preliminary Results on Beam Dynamics of Laser Pulse Shaping Effects in SPARC emittance, laser, simulation, target 1315
 
  • M. Boscolo, M. Ferrario, M.  Migliorati
    INFN/LNF, Frascati (Roma)
  • F. Castelli, S. Cialdi, A.F. Flacco
    INFN-Milano, Milano
  In a photoinjector system the role played by the laser pulse shaping in achieving high quality electron beam is crucial, as it determines the distribution dependent space charge effects in the early stages of the acceleration. A dedicated code to simulate pulse shaping in a laser system and able to generate the corresponding initial electron beam distribution has been developed. Realistic deviations from the ideal flat top pulse give for example a ramp or multi-peaks shape with a raletive rise time, plateau deformation and ripples. The beam dynamics of electron beams with different initial temporal pulse characteristics along the SPARC photoinjector has also been studied with the code PARMELA. More exotic pulse shaping are also discussed. The study presented here gives some indications on the tolerances of the laser beam characteristics for the electron beam quality preservation.  
 
WPAP013 Magnesium Film Photocathodes for High Brilliance Electron Injectors laser, cathode, target, gun 1350
 
  • F. Tazzioli, G. Gatti, C. Vicario
    INFN/LNF, Frascati (Roma)
  • I. Boscolo, S. Cialdi
    INFN-Milano, Milano
  • L. Cultrera, A. Perrone
    Lecce University, Lecce
  • S. Orlanducci, M.L. Terranova
    Università di Roma II Tor Vergata, Roma
  • M. Rossi
    Rome University La Sapienza, Roma
  Advanced high brilliance electron injectors require photocathodes having low thermal emittance, high quantum efficiency (QE) and prompt response. They should be easy to handle and capable of working in the very high electric fileds of a RF gun. Magnesium films deposited by laser ablation and sputtering techniques are discussed and QE measurements are presented.  
 
WPAP014 Development of Electron Gun of Carbon Nanotube Cathode cathode, gun, vacuum, acceleration 1392
 
  • Y. Hozumi
    GUAS/AS, Ibaraki
  • M. Ikeda, S. Ohsawa, T. Sugimura
    KEK, Ibaraki
  We are developing high brightness electron guns utilizing carbon nanotube (CNT) cathodes. Recently, we succeeded to achieved field emission currents to 0.2 A (3 A/cm2) from a triode type CNT cathode of 3 mm diameter. The emission tests were performed at DC100kV acceleration voltage in pulse operations of 50 Hz using 6 nsec pulses. The emission currents were very stable for long term periods of 3 weeks. Photo emission tests from CNT cathode by 266nm laser pulses is also due to be reported simultaneously.  
 
WPAP016 High Brightness Electron Gun for X-Ray Source target, focusing, injection, brightness 1488
 
  • S. Ohsawa, M. Ikeda, T. Sugimura, M. Tawada
    KEK, Ibaraki
  • Y. Hozumi
    GUAS/AS, Ibaraki
  • K. Kanno
    AET Japan, Inc., Kawasaki-City
  A new electron-gun system is under development in order to increase X-ray from a rotating target. In commercial X-ray sources electron beams usually hit targets at the outer part. Owing to deformation by centrifugal force, there has been a limit on electron beam intensities. In order to overcome this difficulty, we adopted a new injection system which strikes inside of a ring-shape projection on a rotating target. It has an advantage in that heated-up points have supports back side against centrifugal force. This merit allows us to raise electron beam to give stronger X-rays.  
 
WPAP017 Experimental Observation of a 100-Femtosecond Single Electron Bunch in Photocathode Linac with Longitudinal Emittance Compensation Technique linac, gun, emittance, cathode 1546
 
  • J. Yang
    RCNP, Osaka
  • K. Kan, T. Kondoh, T. Kozawa, S. Tagawa, Y. Yoshida
    ISIR, Osaka
  The realization of a 100fs electron pulse is important for the studies of ultrafast physical/chemical phenoena with a pump-probe method. We have developed a photocathode linear accelerator (linac) to generate such electron pulse with a magnetic pulse compressor. The nonlinear effect of the magnetic fields in the pulse compression was compensated carefully by optimizing the magnetic fields and the booster linac RF phase. A 105fs(rms) electron bunch with electron charge of 0.1nC was observed experimentally by using a femtosecond streak camera. The beam energy was 35MeV, and the normalized teraservers emittance was lower than 3mm-mrad. The dependences of the pulse length and the emittance on the electron charge were also measured and compared with the theoretical calculations.  
 
WPAP018 Generation of Double-Decker Femtosecond Electron Beams in a Photoinjector linac, gun, laser, emittance 1604
 
  • J. Yang, K. Kan, T. Kondoh, T. Kozawa, Y. Kuroda, S. Tagawa, Y. Yoshida
    ISIR, Osaka
  The femtosecond electron beam is a practical source in the pump-probe experiment for studies of ultrafast physical/chemical reactions in materials, in which a mode-locked ultrashort laser light is used as a probe source. The synchronized time jitter between the electron beam and the laser light limits the time resolution in the experiment. In order to reduce the time jitter, a new concept of synchronized double-decker electron beam generation in a photoinjector was proposed. The double electron beams were observed in an S-band photocathode RF gun by injecting two laser beams which produced with a picosecond laser. The double electron beams were compressed into 400fs(rms) with a phase-space rotation technique in magnetic fields. The beams, which one is used as a pump source and another is used as a probe source, are expected for ultrafast reaction studies in femtosecond resolution.  
 
WPAP021 Status of PPI (Pohang Photo-Injector) for PAL XFEL emittance, gun, cathode, laser 1733
 
  • S.J. Park, C. Kim, I.S. Ko, J.-S. Oh, Y.W. Parc, P.C.D. Park, J.H. Park
    PAL, Pohang, Kyungbuk
  • X.J. Wang
    BNL, Upton, Long Island, New York
  Funding: Supported by the POSCO and the MOST, Korea.

A X-Ray Free Electron Laser (XFEL) project based on the Self-Amplified Spontaneous Emission (SASE) is under progress at the Pohang Accelerator Laboratory (PAL). One of the critical R&D for the PAL XFEL* is to develop the Pohang Photo-Injector (PPI) which is required to deliver electron beams with normalized emittance < 1.5 mm-mrad. In order to achieve the required beam quality with high stability and reliability, we will use photocathode with quantum efficiency > 0.1 % and long lifetime. This will greatly lessen the laser energy requirement for producing flat-top UV pulses, and open the possibility of using only regenerative amplifiers (RGAs) to drive the photocathode RF gun. The RGAs can produce mJs output with much better stability than multi-pass amplifiers. Both the Cs2Te and Mg are under consideration for the possible photo-cathode. To demonstrate the suitability of the Mg and Cs2Te for the future 4th generation light source application, an improved BNL-type S-band RF gun with a high-performance load-lock system will be developed for the PPI. In this article, we present the design concept of the PPI, the expected performance, and report on its development status.

*J.S. Oh, S.J. Park et al., "0.3-nm SASE-FEL at PAL," NIM A528, 582 (2004); S.J. Park, J.S. Oh et al., "Design Study of Low-Emittance Injector for SASE XFEL at Pohang Accelerator Laboratory," FEL2004, Italy, 2004.

 
 
WPAP023 Compact Source of Electron Beam with Energy of 200 kEv and Average Power of 2 kW ion, focusing, power-supply, radiation 1832
 
  • I.V. Kazarezov, V. Auslender, V.E. Balakin, A.A. Bryazgin, A.V. Bulatov, I.I. Glazkov, I.V. Kazarezov, E.N. Kokin, G.S. Krainov, G.I. Kuznetsov, A.M. Molokoedov, A.F.A. Tuvik
    BINP SB RAS, Novosibirsk
  The paper describes a compact electron beam source with average electron energy of 200 keV. The source operates with pulse power up to 2 MW under average power not higher than 2 kW, pulsed beam current up to 10 A, pulse duration up to 2 mks, and repetition rate up to 5 kHz. The electron beam is extracted through aluminium-beryllium alloy foil. The pulse duration and repetition rate can be changed from control desk. High-voltage generator for the source with output voltage up to 220 kV is realized using the voltage-doubling circuit which consists of 30 sections. The insulation type - gas, SF6 under pressure of 8 atm. The cooling of the foil supporting tubes is provided by a water–alcohol mixture from an independent source. The beam output window dimensions are 180?75 mm, the energy spread in the beam +10/-30%, the source weight is 80 kg.  
 
WPAP027 RF Electron Gun with Driven Plasma Cathode cathode, gun, plasma, extraction 1991
 
  • I.V. Khodak, V.A. Kushnir
    NSC/KIPT, Kharkov
  It’s known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.  
 
WPAP028 Modes of Electron Beam Generation in a Magnetron Diode with a Secondary-Emission Cathode cathode, gun, vacuum, target 2027
 
  • V. Zakutin, A. Dovbnya, N.G. Reshetnyak
    NSC/KIPT, Kharkov
  Experiments have shown that the electron current direction can be varied along the diode axis or perpendicular to the axis, depending on the longitudinal magnetic field amplitude and distribution. The diode had a copper cathode diameter 40 mm and 15 mm anode-cathode gap. Several modes of electron beam generation are realized, namely, open, closed, and intermediate. In the first case, at a cathode magnetic field of ~ 1200 Oe, that falls off approaching the diode output down, and at a cathode voltage of 50 kV, the diode generates a tubular electron beam of a current 50 A and the anode current was about 1 % of the beam current. In the second case, the electron current was going to the anode, the secondary-emission multiplication of electrons being retained. At a cathode voltage of ~ 45 kV, the anode current was ~ 5 A, and the beam current was practically absent. This was attained by decreasing the magnetic field to ~ 1.11.2 of the Hell field value and by increasing the magnetic field towards the diode output. In the intermediate mode with a cathode voltage of ~ 45 kV the direct beam current measured was ~ 5 A, and the anode current was ~ 7 A.  
 
WPAP031 Use of Multiobjective Evolutionary Algorithms in High Brightness Electron Source Design gun, emittance, laser, cathode 2188
 
  • I.V. Bazarov, C.K. Sinclair
    Cornell University, Department of Physics, Ithaca, New York
  • I. Senderovich
    Cornell University, Ithaca, New York
  Funding: Supported by Cornell University.

We describe the use of multiobjective evolutionary algorithms (MOEAs) for the design and optimization of a high average current, high brightness electron injector for an Energy Recovery Linac (ERL). By combining MOEAs with particle tracking, including space charge effects, and by employing parallel computing resources, we explored a multidimensional parameter space with 22 independent variables for a DC gun based injector which is being constructed at Cornell University. The simulated performance of the optimized injector is found to be excellent, with normalized rms emittances as low as 0.1 mm-mrad for a 77 pC bunch, and 0.7 mm-mrad for a 1 nC bunch. We detail the advantages and flexibility of MOEAs as a powerful tool well suited for wide application in solving various problems in the accelerator field.

 
 
WPAP033 State-of-the-Art Electron Guns and Injector Designs for Energy Recovery Linacs (ERL) gun, emittance, booster, cathode 2292
 
  • A.M.M. Todd, A. Ambrosio, H. Bluem, V. Christina, M.D. Cole, M. Falletta, D. Holmes, E. Peterson, J. Rathke, T. Schultheiss, R. Wong
    AES, Princeton, New Jersey
  • I. Ben-Zvi, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, H. Hahn, D. Kayran, J. Kewisch, V. Litvinenko, G.T. McIntyre, T. Nicoletti, J. Rank, T. Rao, J. Scaduto, K.-C. Wu, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • S.V. Benson, E. Daly, D. Douglas, H.F.D. Dylla, L. W. Funk, C. Hernandez-Garcia, J. Hogan, P. Kneisel, J. Mammosser, G. Neil, H.L. Phillips, J.P. Preble, R.A. Rimmer, C.H. Rode, T. Siggins, T. Whitlach, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  • I.E. Campisi
    ORNL, Oak Ridge, Tennessee
  • P. Colestock, J.P. Kelley, S.S. Kurennoy, D.C. Nguyen, W. Reass, D. Rees, S.J. Russell, D.L. Schrage, R.L. Wood
    LANL, Los Alamos, New Mexico
  • D. Janssen
    FZR, Dresden
  • J.W. Lewellen
    ANL, Argonne, Illinois
  • J.S. Sekutowicz
    DESY, Hamburg
  • L.M. Young
    TechSource, Santa Fe, New Mexico
  Funding: This work is supported by NAVSEA, NSWC Crane, the Office of Naval Research, the DOD Joint Technology Office and by the U.S. DOE.

A key technology issue of ERL devices for high-power free-electron laser (FEL) and 4th generation light sources is the demonstration of reliable, high-brightness, high-power injector operation. Ongoing programs that target up to 1 Ampere injector performance at emittance values consistent with the requirements of these applications are described. We consider that there are three possible approaches that could deliver the required performance. The first is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. Such a 750 MHz device is being integrated and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility beginning in 2007. The second approach is a high-current normal-conducting RF photoinjector. A 700 MHz gun will undergo thermal test in 2006 at the Los Alamos National Laboratory, which, if successful, when equipped with a suitable cathode, would be capable of 1 Ampere operation. The last option is an SRF gun. A half-cell 703 MHz SRF gun capable of delivering 1.0 Ampere will be tested to 0.5 Ampere at the Brookhaven National Laboratory in 2006. The fabrication status, schedule and projected performance for each of these state-of-the-art injector programs will be presented.

 
 
WPAP034 Positron Emulator for Commissioning ILC Positron Source positron, target, damping, linac 2321
 
  • H. Wang, W. Gai, K.-J. Kim, W. Liu
    ANL, Argonne, Illinois
  Funding: U.S. DOE.

It is apparent that the gamma-ray based positron source components including positron linac and damping rings for ILC can not be easily commissioned until the electron beam is fully conditioned at high energies (> 150 GeV). In this paper, we discuss a scheme that could use a short and energetic electron beam scattered through a set of carefully selected targets to simulate certain behaviors of the positron beam, such as beam emittance and energy spread. The basic idea is to make the phase space distribution of the scattered electron beam to reflect certain aspects of the positron beam distributions. Subsequently, the positron source elements such as capture optics, linacs and even damping ring could be effectively commissioned before ILC colliding electron beam is ready. The simulation results using EGS4 for beam scattering and PARMELA for beam dynamics are presented.

 
 
WPAP035 Emittance Compensation in Flat Beam Production in an RF Gun Linac emittance, space-charge, simulation, gun 2399
 
  • S. Wang
    ANL, Argonne, Illinois
  Funding: This research is supported by the U.S. Department of Energy under contract DE-FG02-92ER40747 and the National Science Foundation under contract NSF PHY-0244793.

Ya. Derbenev Proposed a flat beam production method in RF gun Linac, which passes the electron beam through a matched skew quadrupole channel and transform the initially transversely round beam into a flat beam. Fermilab/NICADD Photoinjector Laboratory has performed a lot of experiments, a ratio of 50 of the transverse emittances in x and y plane has been achieved and the ratio of 100 and higher is underway of research. In this paper, the S-shaped flat beam, found both in experiments and simulations, is investigated. The nonlinear transverse force from the RF field when the beam passes the superconducting cavity is found to be one of the sources which produce the transverse S-shape distribution and increase the emittance. An extra solenoid located before the superconducting cavity is proposed to be added to adjust the beam transverse size when the beam passes through the cavity. The resulted transverse nonlinear space-charge force is used to counter-act against the nonlinear transverse force from the RF field. PARMELA simulations have shown that, with proper setup of the extra solenoid, the emittance ratio can be enhanced by a factor of 2 and the S-shaped transverse distribution can also be eliminated.

 
 
WPAP036 Determination of the Field Enhancement Factor on Photocathode Surface Via the Schottky Effect laser, cathode, photon, emittance 2425
 
  • Z.M. Yusof, M.E. Conde, W. Gai
    ANL, Argonne, Illinois
  Funding: U.S. Department of Energy.

Using photons with energy that is less than the work function, we employ the Schottky effect to determine the field enhancement factor on the surface of a Mg photocathode. The Schottky effect is manifested via a shift in the threshold for photoemission as the amplitude of the RF in the photoinjector gun is varied. From the threshold condition, we can directly determine the field enhancement factor on the cathode surface. This is a viable technique to obtain the field enhancement factor of surfaces of other materials such as Nb and Cu.

 
 
WPAP037 Novel Method of Emittance Preservation in ERL Merging System in Presence of Strong Space Charge Forces emittance, space-charge, gun, linac 2512
 
  • D. Kayran, V. Litvinenko
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy and partially funded by the US Department of Defence

Energy recovery linacs (ERLs) are potential candidates for the high power and high brightness electron beams sources. The main advantages of ERL are that electron beam is generated at relatively low energy, injected and accelerated to the operational energy in a ERL loop with a common linac, then is decelerated in the same loop down to injection energy and dumped. The intrinsic part of any ERL is a merging system for the low-energy beam with a high-energy beam passing around the ERL loop. One of the challenges for generating high charge high brightness e-beam in ERL is development of merging system, which provides achromatic condition for space charge dominated beam and which is compatible with the emittance compensation scheme. In this paper we present principles of operation of such merging system. We also describe an example of such system, which we call Zigzag or Z-system. We use a specific implementation for R&D ERL at Brookhaven for illustration.

 
 
WPAP038 Photoemission Studies on BNL/AES/JLab all Niobium, Superconducting RF Injector laser, cathode, space-charge, gun 2556
 
  • T. Rao, I. Ben-Zvi, A. Burrill, H. Hahn, D. Kayran, Y. Zhao
    BNL, Upton, Long Island, New York
  • M.D. Cole
    AES, Medford, NY
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  Funding: Under contract with the U.S. DOE, Contract No. DE-AC02-98CH10886.

Photoemission from all niobium superconducting injector is of considerable interest for the development of higher average current electron sources. In the past year, we have generated photocurrent from such an injector by irradiating the back wall of the 1/2 cell cavity with 248 nm and 266 nm laser beams. In this paper, we present the results of these measurements including the quantum efficiency, and its dependence on the field and wavelength. Issues related to the quenching of the cavity by the laser radiation will also be addressed.

 
 
WPAP041 Time Dependent Quantum Efficiency and Dark Current Measurements in an RF Photocathode Injector with a High Quantum Efficiency Cathode gun, cathode, linac, laser 2681
 
  • R.P. Fliller, H. Edwards
    Fermilab, Batavia, Illinois
  • W. Hartung
    NSCL, East Lansing, Michigan
  Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE and by NICADD.

A system was developed at INFN Milano for preparing cesium telluride photo-cathodes and transferring them into an RF gun under ultra-high vacuum. This system has been in use at the Fermilab NICADD Photo-Injector Laboratory (FNPL) since 1997. A similar load-lock system is used at the TeSLA Test Facility at DESY-Hamburg. Two 1.625-cell high duty cycle RF guns have been fabricated for the project. Studies of the photo-emission and field emission ("dark current") behavior of both RF guns have been carried out. Unexpected phenomena were observed in one of the RF guns. In situ changes in the cathode's quantum efficiency and dark current with time were seen during operation of the photo-injector. These changes were correlated with the magnetostatic field at the cathode.* In addition, multipacting is observed in the RF guns under certain conditions. Recent measurements indicate a correlation between multipacting, anomalous photo-emission behavior, and anomalous field emission behavior. Results will be presented.

*W. Hartung, J.-P. Carneiro, H. Edwards, M. Fitch, M. Kuchnir, P. Michelato, D. Sertore, in Proceedings of the 2001 Particle Accelerator Conference, p. 2239-2241.

 
 
WPAP042 Progress on Using NEA Cathodes in an RF Gun gun, ion, cathode, simulation 2708
 
  • R.P. Fliller, T. G. Anderson, H. Edwards
    Fermilab, Batavia, Illinois
  • H. Bluem, T. Schultheiss
    AES, Princeton, New Jersey
  • M. Huening
    DESY, Hamburg
  • C.K. Sinclair
    Cornell University, Department of Physics, Ithaca, New York
  Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE and by NICADD. AES personnel were supported under DOE SBIR contract #DE-FG02-04ER838.

RF guns have proven useful in multiple accelerator applications, and are an attractive electron source for the ILC. Using a NEA GaAs photocathode in such a gun allows for the production of polarized electron beams. However the lifetime of a NEA cathode in this environment is reduced by ion and electron bombardment and residual gas oxidation. We report progress made with studies to produce a RF gun using a NEA GaAs photocathode to produce polarized electron beams. Attempts to reduce the residual gas pressure in the gun are discussed. Initial measurements of ion flux through the cathode port are compared with simulations of ion bombardment. Future directions are also discussed.

 
 
WPAP043 Production of Transverse Controllable Laser Density Distribution in Fermilab/NICADD Photoinjector laser, simulation, emittance, space-charge 2783
 
  • J.L. Li, J.L. Li
    Rochester University, Rochester, New York
  • P. Piot, R. Tikhoplav
    Fermilab, Batavia, Illinois
  The Fermilab/NICADD photoinjector laboratory consist of a photoemission electron source based on an L band rf-gun. The CsTe photocathode is illuminated by an ultrashort UV laser. The transport line from the laser to the photocathode was recently upgraded to allow imaging of an object plane located ~20 m from the photocathode. This upgrade allows the generation of transverse laser distributions with controlled nonuniformity, yielding the production of an electron beam with various transverse densities patterns. Measuring the evolution of the artificial pattern on the electron bunch provides information that can be used to benchmark numerical simulations and investigate the impact of space charge. Preliminary data on these investigations are presented in the present paper.  
 
WPAP044 Advanced Electromagnetic Analysis for Electron Source Geometries cathode, gun, space-charge, acceleration 2815
 
  • M. Hess, C.S. Park
    IUCF, Bloomington, Indiana
  One of the challenging issues for analytically modeling electron sources, such as rf photoinjectors, is how to incorporate fully electromagnetic effects which are generated by the electron beam. The main difficulties that arise in finding an analytical solution of the electromagnetic fields are due to the complex shape of the conductor boundary, as well as the complicated structure of the beam density and current. Both of these problems can be handled self-consistently by using an electromagnetic Green’s function method. In this paper, we present a solution to the exact electromagnetic fields, which were derived from the Green’s function, for a simplified electron source conductor geometry, namely a semi-infinite circular pipe with an endcap. We assume that the beam currents are in the axial direction and satisfy the continuity equation in conjunction with the beam charge density, but may have arbitrary spatial and time dependency. We discuss how these analytical methods may be extended to include in the effect of one or multiple irises, which are found in rf photoinjector systems.  
 
WPAP045 Ion Back-Bombardment of GaAs Photocathodes Inside DC High Voltage Electron Guns laser, vacuum, gun, ion 2875
 
  • J.M. Grames, P. Adderley, J. Brittian, D. Charles, J. Clark, J. Hansknecht, M. Poelker, M.L. Stutzman, K.E.L. Surles-Law
    Jefferson Lab, Newport News, Virginia
  Funding: This work was supported by U.S. DOE Contract No. DE-ACO5-84-ER40150.

The primary limitation for sustained high quantum efficiency operation of GaAs photocathodes inside DC high voltage electron guns is ion back-bombardment of the photocathode. This process results from ionization of residual gas within the cathode/anode gap by the extracted electron beam, which is subsequently accelerated backwards to the photocathode. The damage mechanism is believed to be either destruction of the negative electron affinity condition at the surface of the photocathode or damage to the crystal structure by implantation of the bombarding ions. This work characterizes ion formation within the anode/cathode gap for gas species typical of UHV vacuum chambers (i.e., hydrogen, carbon monoxide and methane). Calculations and simulations are performed to determine the ion trajectories and stopping distance within the photocathode material. The results of the simulations are compared with test results obtained using a 100 keV DC high voltage GaAs photoemission gun and beamline at currents up to 10 mA DC.

 
 
WPAP046 Injection Options for 12 GeV CEBAF Upgrade gun, simulation, recirculation, injection 2911
 
  • R. Kazimi, J. F. Benesch, Y.-C. Chao, J.M. Grames, G.A. Krafft, M. Tiefenback, B.C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by DOE Contract DE-AC05-84ER40150.

Jefferson Lab is planning to upgrade the CEBAF accelerator from 6 to 12 GeV. In order to achieve this, the beam energy at injection into the main accelerator needs to increase from 67 MeV to either 123 or 134 MeV depending on the location of the new experimental hall relative to the accelerator. The present 100 keV electron source and beam formation to 5 MeV will remain unchanged; however, the present accelerating cryomodules in the injector cannot reach the higher injection energies. Consequently, two options for attaining these energies are considered: (1) replacing the present injector cryomodules with new, higher gradient cryomodules, or (2) re-circulating the beam through the existing cryomodules to achieve the necessary energy gain in two passes. In this paper we present simulation results and list the advantages and disadvantages of these two options.

 
 
WPAP050 A High Average Current DC GaAs Photocathode Gun for ERLs and FELs gun, vacuum, cathode, laser 3117
 
  • C. Hernandez-Garcia, S.V. Benson, D.B. Bullard, H.F.D. Dylla, K. Jordan, C. M. Murray, G. Neil, M.D. Shinn, T. Siggins, R.L. Walker
    Jefferson Lab, Newport News, Virginia
  Funding: This work supported by The Office of Naval Research under contract to the Dept. of Energy, the Air Force Research Lab, and the Commonwealth of Virginia.

The Jefferson Lab (JLab) 10 kW IR Upgrade FEL DC GaAs photocathode gun is presently the highest average current electron source operational in the U.S., delivering a record 9.1 mA CW, 350 kV electron beam with 122 pC/bunch at 75 MHz rep rate. Pulsed operation has also been demonstrated with 8 mA per pulse (110 pC/bunch) in 16 ms-long pulses at 2 Hz rep rate. Routinely the gun delivers 5 mA CW and pulse current at 135 pC/bunch for FEL operations. The Upgrade DC photocathode gun is a direct evolution of the DC photocathode gun used in the previous JLab 1 kW IR Demo FEL. Improvements in the vacuum conditions, incorporation of two UHV motion mechanisms (a retractable cathode and a photocathode shield door) and a new way to add cesium to the GaAs photocathode surface have extended its lifetime to over 500 Coulombs delivered between re-cesiations (quantum efficiency replenishment). With each photocathode activation quantum efficiencies above 6% are routinely achieved. The photocathode activation and performance will be described in detail.

 
 
WPAP057 Three-Dimensional Theory and Simulation of an Ellipse-Shaped Charged-Particle Beam Gun simulation, emittance, vacuum, focusing 3372
 
  • R. Bhatt, T. Bemis, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
  Funding: U.S. DOE: Grant No. DE-FG02-95ER40919, Grant No. DE-FG02-01ER54662, Air Force Office of Scientific Research: Grant No. F49620-03-1-0230, and the MIT Deshpande Center for Technological Innovation.

A three-dimensional (3D) theory of non-relativistic, laminar, space-charge-limited, ellipse-shaped, charged-particle beam formation has been developed recently (Bhatt and Chen, PR:ST-AB, submitted Dec. 2004), whereby charged particles (electrons or ions) are accelerated across a diode by a static voltage differential and focused transversely by Pierce-type external electrodes placed along analytically specified surfaces. The treatment is extended to consider the perturbative effects of anode hole lensing, thermal isolation of the emitter, finiteness and nonuniformities of beam-forming electrodes, and an initial thermal spread. Analytic and semi-analytic results are presented along with 3D simulations utilizing the 3D trajectory code, OMNITRAK. Considerations with regard to beam matching into a periodic magnetic focusing lattice are discussed.

 
 
WPAP058 The ILC Polarized Electron Source laser, cathode, gun, polarization 3420
 
  • A. Brachmann, J.E. Clendenin, E.G. Garwin, R.E. Kirby, D.-A.L. Luh, T.V.M. Maruyama, D.C. Schultz, J. Sheppard
    SLAC, Menlo Park, California
  • R.X.P. Prepost
    UW-Madison/PD, Madison, Wisconsin
  Funding: This work is supported by U.S. DOE contracts DE-AC02-76SF00515 (SLAC) and DE-AC02-76ER00881 (UW).

The SLC polarized electron source (PES) can meet the expected requirements of the International Linear Collider (ILC) for polarization, charge and lifetime. However, experience with newer and successful PES designs at JLAB, Mainz and elsewhere can be incorporated into a first-generation ILC source that will emphasize reliability and stability without compromising the photocathode performance. The long pulse train for the ILC may introduce new challenges for the PES, and in addition more reliable and stable operation of the PES may be achievable if appropriate R&D is carried out for higher voltage operation and for a simpler load-lock system. The outline of the R&D program currently taking shape at SLAC and elsewhere is discussed. The principal components of the proposed ILC PES, including the laser system necessary for operational tests, are described.

 
 
WPAT016 Stable Low Noise RF Source for Main Ring storage-ring, feedback, synchrotron, scattering 1494
 
  • G.Y. Kurkin
    BINP SB RAS, Novosibirsk
  • P. Wang
    DU/FEL, Durham, North Carolina
  The Duke Storage ring is a 1 Gev electron ring, which is designed for driving UV-VUV FEL. It also provides variable energy high intensive gamma rays by Compton back scattering. It requires an RF master oscillator with very low phase noise. We built a Surface Acoustic Wave (SAW) Oscillator. However, the long-term stability does not meet requirements for FEL ring. Previously we used a commercial signal generator HP 4400B as the master oscillator. It has excellent long-term stability, but the phase noise is not acceptable. A phase feedback loop has been added between the SAW oscillator and the HP source, which provides us an excellent RF source. The design details and the test results are presented in this paper.  
 
WPAT026 Status of 34 GHZ, 45 MW Pulsed Magnicon gun, cathode, linear-collider, collider 1922
 
  • O.A. Nezhevenko, V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield, M.A. LaPointe
    Yale University, Physics Department, New Haven, CT
  • E.V. Kozyrev
    BINP SB RAS, Novosibirsk
  • S.V. Shchelkunov
    Columbia University, New York
  Funding: Research supported by the Department of Energy, Division of High Energy Physics.

A high efficiency, high power magnicon at 34.272 GHz has been designed and built as a microwave source to develop RF technology for a future multi-TeV electron-positron linear collider. To develop this technology, this new RF source is being perfected for necessary tests of accelerating structures, RF pulse compressors, RF components, and to determine limits of breakdown and metal fatigue. After preliminary RF conditioning the magnicon produced an output power of 10.5 MW in 0.25 microsecond pulses, with a gain of 54 dB. The new results of the experimental tests after the tube conditioning was resumed are presented in the paper.

 
 
WPAT027 Recent Results from the X-Band Pulsed Magnicon Amplifier target, plasma, gun, vacuum 1979
 
  • O.A. Nezhevenko, V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • A.W. Fliflet, S.H. Gold
    NRL, Washington, DC
  • J.L. Hirshfield, M.A. LaPointe
    Yale University, Physics Department, New Haven, CT
  • A.K. Kinkead
    ,
  Funding: Research supported by the Department of Energy, Office of High Energy Physics, and the Office of Naval Research.

A frequency-doubling magnicon amplifier at 11.4 GHz has been designed and built as the prototype of an alternative microwave source for the Next Linear Collider project, and to test high power RF components and accelerating structures. The tube is designed to produce ~60 MW, ~1.2 microsecond pulses at 58% efficiency and 59 dB gain, using a 470 kV, 220 A, 2 mm-diameter beam. In the first tests the output power was limited to a level of 26 MW in a 200 nsec pulse. This limitation was caused by the oscillations in the tube collector. Experimental results of the magnicon tests with the new collector are presented in this paper

 
 
WPAT029 The RF Experimental Program in the Fermilab MUCOOL Test Area linac, background, target, site 2104
 
  • J. Norem
    ANL, Argonne, Illinois
  • A. Bross, A. Moretti, Z. Qian
    Fermilab, Batavia, Illinois
  • R.P. Johnson
    Muons, Inc, Batavia
  • D. Li, M.S. Zisman
    LBNL, Berkeley, California
  • R.A. Rimmer
    Jefferson Lab, Newport News, Virginia
  • R. Sandstrom
    CUI, Geneva
  • Y. Torun
    IIT, Chicago, Illinois
  Funding: DOE

The rf R&D program for high gradient, low frequency cavities to be used in muon cooling systems is underway in the Fermilab Muon Test Area. Cavities at 805 and 201 MHz are used for tests of conditioning techniques, surface modification and breakdown studies. This work has the Muon Ionization Cooling Experiment (MICE) as its immediate goal and efficient muon cooling systems for neutrino sources and muon colliders as the long term goal. We study breakdown, and dark current productions under a variety of conditions.

 
 
WPAT031 Design and Operation of a High Power L-Band Multiple Beam Klystron klystron, cathode, focusing, higher-order-mode 2170
 
  • A. Balkcum, H.P. Bohlen, M. Cattelino, L. Cox, M. Cusick, S. Forrest, F. Friedlander, A. Staprans, E.L. Wright, L. Zitelli
    CPI, Palo Alto, California
  • K. Eppley
    SAIC, Burlington, Massachusetts
  A 1.3 GHz, 10 MW, higher-order-mode multiple beam klystron (MBK) has been developed for the TESLA program. The relative advantages of such a device are many-fold. Multiple beams generate higher beam currents and thereby require much lower operating voltages which allows for the use of smaller, less expensive modulators. A lower perveance per cathode can also be used which leads to higher operating efficiencies. Higher-order-mode cavities allow for the use of much larger cathodes which leads to lower cathode current density loadings and subsequently longer cathode lifetimes. This requires that the cathodes be located far off the geometric axis of the device. The compromise is an increase in the complexity of the magnetic focusing circuit required to transport the off-axis electron beams. Such a device has been successfully built and tested. Excellent beam transmission has been achieved (99.5% DC and 98% at RF saturation). A peak power of 10 MW with 150 kW of average power and 60% efficiency, 49 dB gain have also been measured. The achieved low cathode loading of 2.1 A/cm2 corresponds to an expected cathode life of over 140,000 operational hours.  
 
WPAT034 The CEBAF Separator Cavity Resonance Control System resonance, controls, monitoring, linac 2339
 
  • M.J. Wissmann, AA. Guerra, C. Hovater, T. Plawski
    Jefferson Lab, Newport News, Virginia
  Funding: This work supported by the U.S. Department of Energy under contract DE-AC05-84ER40150.

The CEBAF energy upgrade from 6 GeV to 12GeV will increase the range of beam energies available to the experimental halls. RF deflection cavities (separators) are used to direct the electron beam to the three experimental halls. Consequently with the increase in RF separator cavity gradient needed for the higher energies, RF power will also increase requiring the cavities to have active resonance control. At the 6 GeV energy, the cavities are tuned mechanically and then stabilized with Low Conductivity Water (LCW), which is maintained at constant temperature of 95o Fahrenheit. This is no longer feasible and an active resonance control system, that controls both water temperature and flow has been built. The system uses a commercial PLC with embedded PID controls to control water temperature and flow to the cavities. The system allows the operator to remotely adjust temperature/flow and consequently cavity resonance for the full range of beam energies. Ultimately closed loop control will be maintained by monitoring the cavities reflected power. This paper describes this system.

 
 
WPAT049 The Penetrability of a Thin Metallic Film Inside the RF Field cathode, pick-up, impedance, laser 3073
 
  • Y. Zhao, I. Ben-Zvi, R.H. Beuttenmuller, X.Y. Chang, C. Chen, R. Di Nardo, T. Rao
    BNL, Upton, Long Island, New York
  Funding: Under contract with the U.S. Department of Energy, Contract Number DE-AC02-98CH10886.

Thin metallic film was widely applied in varies area. Especially, recently we are planning to apply it in a "Secondary emission enhanced photo-injector," of which a diamond cathode is coated with a golden film or so on its back to serve as a current path. The thickness of the film is originally considered to be in the order of 10 nm, which is much less than the skin depth, say 1/200. Since it is so thin, that intuitively the RF filed is penetrable. However, we found it is not true. The film will block most of the field. This paper addresses theoretic analysis as well as the experimental results. All demonstrated that the penetrability of a thin film is very poor. Consequently, most of the RF current will flow on the thin film causing a serous heating problem.

 
 
WPAT051 Development of Toshiba L-Band Multi-Beam Klystron for European XFEL Project cathode, klystron, gun, simulation 3153
 
  • Y.H. Chin
    KEK, Ibaraki
  • S. Choroba
    DESY, Hamburg
  • M. Y. Miyake, Y. Yano
    Toshiba, Yokohama
  A 10MW L-band multi-beam klystron (MBK)is under develpment at Toshiba, Japan for DESY X-FEL and a future linear collider projects. The design goals are to have 10MW peak power with 65% efficiency at 1.5 ms pulse length at 10Hz repetition rates. The Toshiba MBK has six low-perveance beams operated at low voltage of 115kV (for 10MW) to enable a higher efficiency than a single-beam klystron for a similar power. The prototyp·10-0 has been built and is now under testing. At the first step, it was tested without RF and operates stably at the cathode voltage of 115KV at 1.7ms pulse length at 10Hz repetition rate with beam transmission of better than 99%. No spurious oscillation was observed. The testing is now progressed with RF on. Up to date of November 10, 2004, The output power of 10.3MW has been demonstrated at the beam voltage of 115kV with efficinecy of 68.4% at the RF pulse length of 1ms at 10Hz. The testing is under way to increase the RF pulse length to the goal value of 1.5ms. This paper summarizes the design and the testing results.  
 
WPAT065 HLS RF System Improvement in NSRL Phase II Project vacuum, storage-ring, controls, coupling 3653
 
  • K. Jin, Y. An, L. Feng, G. Huang, G. Liu, G. Wang, X. Zeng
    USTC/NSRL, Hefei, Anhui
  Hefei Light Source (HLS) is mainly composed of an 800 MeV electron storage ring and a 200 MeV Linac functioning as its injector. The RF system has been improved successfully for HLS storage-ring in NSRL Phase II Project. In this paper, the improvement of generator and power transmission system, the development of a new RF cavity and the perfection of RF controls are described in detail. The results and some analyses are presented.  
 
WPAT068 Development of Low Level RF Control Systems for Superconducting Heavy Ion Linear Accelerators, Electron Synchrotrons and Storage Rings rfq, synchrotron, booster, storage-ring
 
  • B. A. Aminov, A. Borisov, S. K. Kolesov, H. Piel
    CRE, Wuppertal
  • M. Pekeler, C. Piel
    ACCEL, Bergisch Gladbach
  Since 2001 ACCEL Instruments is supplying low level RF control systems together with turn key cavity systems. The early LLRF systems used the well established technology based on discrete analogue amplitude and phase detectors and modulators. Today analogue LLRF systems can make use of advanced vector demodulators and modulators combined with a fast computer controlled analogue feed back loop. Feed forward control is implemented to operate the RF cavity in an open loop mode or to compensate for predictable perturbations. The paper will introduce the general design philosophy and show how it can be adapted to different tasks as controlling a synchrotron booster nc RF system at 500 MHz, or superconducting storage ring RF cavities, as well as a linear accelerator at 176 MHz formed by a chain of individually driven and controlled superconducting λ/2 cavities.  
 
WPAT072 A 1.3GHz Inductive Output Tube for Particle Accelerators gun, cathode, target, synchrotron 3883
 
  • E. Sobieradzki, A.E. Wheelhouse
    e2v technologies, Chelmsford, Essex
  There is an increasing requirement for RF power sources in the L-band frequency range for operation in particle accelerators. The paper describes the development and presents test results of a new inductive output tube (IOT) for use at 1.3GHz. A target specificationof 16kW cw output power at an efficiency of 60% was set. The paper discusses progress to date having used an electron gun geometry that minimizes transit time effects in the cathode to grid gap.  
 
WPAT084 A NEW DESIGN FOR A SUPER-CONDUCTING CAVITY INPUT COUPLER coupling, vacuum, resonance, linac 4141
 
  • H. Matsumoto, S. Kazakov, K. Saito
    KEK, Ibaraki
  Funding: Toshiba Electron Tube & Devices Co. Ltd., Tochigi, Otawa, Japan.

An attractive structure using capacitive coupling has been found for the input coupler for the 45 MV/m versions of the International Linear Collider (ILC) project. The coupler supports an electrical field gradient of ~1 kV/m around the rf window ceramic with 500 kW through power, a VSWR of 1.1 and a frequency bandwidth of 460 MHz. No unwanted resonances were found in the rf window near the first and second harmonics of the operation frequency.

 
 
WPAT088 Performance of TESLA Cavities After Fabrication and Preparation in Industry vacuum, pick-up 4221
 
  • M. Pekeler, S. Bauer, P. vom Stein
    ACCEL, Bergisch Gladbach
  • W. Anders, J. Knobloch
    BESSY GmbH, Berlin
  • W.-D. Müller
    DESY, Hamburg
  In order to demonstrate cw operation of TESLA cavities in linear accelerators driving FEL applications, two TESLA cavities were manufactured and prepared by ACCEL for BESSY. After production, both cavities were prepared for vertical test at ACCEL's premises using state of the art chemical polishing and high pressure water rinsing techniques. The cavities were tested in DESY's vertical RF test installation. Accelerating gradients close to 25 MV/m were reached. One cavity was completed with a helium vessel modified for cw operation and prepared with chemical polishing, high pressure water rinsing, and assembled with the required High Power Coupler at ACCEL. The fully dressed cavity was then shipped under vacuum to BESSY and tested in the horizontal cryostat HoBiCaT. Horizontal RF test results will be presented and compared with the vertical test results.  
 
WOAB005 The Status of Turkic Accelerator Complex Proposal factory, linac, luminosity, proton 449
 
  • S. Sultansoy, M. Yilmaz
    Gazi University, Faculty of Science and Arts, Ankara
  • O. Cakir, A.K. Ciftci, E. Recepoglu, O. Yavas
    Ankara University, Faculty of Sciences, Tandogan/Ankara
  Recently, the Turkic Accelerator Complex (TAC) is proposed as a regional facility for accelerator based fundamental and applied research. The complex will include linac on ring type electron-positron collider as a phi, charm and tau factory, linac based free electron laser (FEL), ring based third generation syncrothron radiation (SR) source and a few GeV proton accelerator. Preliminary estimations show that hundred inverse femto barn integral luminosity per year can be achieved for factory options. The FEL facility is planned to obtain laser beam between IR and soft X-ray region. In addition, SR facility will produce photon beams in UV and X-ray region. The proton accelerator will give opportunity to produce muon and neutron beams for applied research. The current status of the conceptual study of the complex is presented.  
 
WOAC001 Aberration Correction in Electron Microscopy quadrupole, sextupole, multipole, acceleration 44
 
  • H.H. Rose, W. Wan
    LBNL, Berkeley, California
  The resolution of conventional electron microscopes is limited by spherical and chromatic aberrations. Both defects are unavoidable in the case of static rotationally symmetric electromagnetic fields (Scherzer theorem). Multipole correctors and electron mirrros have been designed and built, which compensate for these aberrations. The principles of correction will be demonstrated for the tetrode mirror, the quadrupole-octopole corrector and the hexapole corrector. Electron mirrors require a magnetic beam separator free of second-order aberrations. The multipole correctors are highly symmetric telescopic systems compensating for the defects of the objective lens. The hexapole corrector has the most simple structure yet eliminates only the spherical aberration, whereas the mirror and the quadrupole-octopole corrector are able to correct for both aberrations. Chromatic correction is achieved in the latter corrector by cossed electric and magnetic quadrupoles acting as first-order Wien filters. Micrographs obtained with aberration-corrected electron microscopes will be shown demonstrating the improvement in resolution to better than 1 Angstroem.  
 
WOPA002 Experimental Results from the Small Isochronous Ring space-charge, cyclotron, simulation, focusing 159
 
  • E.P. Pozdeyev
    Jefferson Lab, Newport News, Virginia
  • F. Marti, R.C. York
    NSCL, East Lansing, Michigan
  • J.A. Rodriguez
    CERN, Geneva
  Funding: Work supported by NSF Grant # PHY-0110253 and DOE Contract DE-AC05-84ER40150.

The Small Isochronous Ring (SIR) is a compact, low-energy storage ring designed to investigate the beam dynamics of high-intensity isochronous cyclotrons and synchrotrons at the transition energy. The ring was developed at Michigan State University and has been operational since December 2003. It stores 20 keV hydrogen beams with a peak current of 10-20 microamps for up to 200 turns. The transverse and longitudinal profiles of extracted bunches are measured with an accuracy of approximately 1 mm. The high accuracy of the measurements makes the experimental data attractive for validation of multi-particle space charge codes. The results obtained in the ring show a fast growth of the energy spread induced by the space charge forces. The energy spread growth is accompanied by a breakup of the beam bunches into separated clusters that are involved in the vortex motion specific to the isochronous regime. The experimental results presented in the paper show a remarkable agreement with simulations performed with the code CYCO. In this paper, we discuss specifics of space charge effects in the isochronous regime, present results of experiments in SIR, and conduct a detailed comparison of the experimental data with results of simulations.

 
 
ROAC007 RF Breakdown in Normal Conducting Single-cell Structures vacuum, simulation, ion, linear-collider 595
 
  • V.A. Dolgashev, C.D. Nantista, S.G. Tantawi
    SLAC, Menlo Park, California
  • Y. Higashi, T. Higo
    KEK, Ibaraki
  Funding: Work supported by the U.S. Department of Energy contract DE-AC02-76SF00515.

Operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdown. The limit depends on multiple parameters, including input rf power, rf circuit, cavity shape and material. Experimental and theoretical study of the effects of these parameters on the breakdown limit in full scale structures is difficult and costly. We use 11.4 GHz single-cell traveling wave and standing wave accelerating structures for experiments and modeling of rf breakdown behavior. These test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype multicell structures for the X-band linear collider. Fields elsewhere in the test structures are significantly lower than that of the single cell. The setup uses matched mode converters that launch the circular TM01 mode into short test structures. The test structures are connected to the mode launchers with vacuum rf flanges. This setup allows economic testing of different cell geometries, cell materials and preparation techniques with short turn-around time. Simple 2D geometry of the test structures simplifies modeling of the breakdown currents and their thermal effects.

 
 
ROAC009 World Record Accelerating Gradient Achieved in a Superconducting Niobium RF Cavity superconductivity, vacuum, coupling 653
 
  • R.L. Geng, A.K. Seaman, V.D. Shemelin
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • H. Padamsee
    Cornell University, Ithaca, New York
  Funding: Work supported by NSF.

On November 16, 2004, an accelerating gradient of 46 MV/m was achieved (CW) in a superconducting niobium cavity with an unloaded quality factor (Q0) over 1·1010 at a temperature of 1.9 K. This represents a world record gradient in a niobium RF resonator. At a reduced temperature of 1.5-1.6 K, an enhanced Q0 was measured, ranging from 7·1010 at 5 MV/m to 2·1010 at 45 MV/m. The 1.3 GHz single-cell cavity has a reduced ratio of Hpk/Eacc, ensured by a reentrant geometry. The maximum peak surface electric and magnetic field exceeded 100 MV/m and 1750 Oe respectively. A soft multipacting barrier (predicted by calculations) was observed near 25 MV/m gradient and was easily processed through. Field emission in the cavity was negligibly small, and the highest field was limited by thermal breakdown. The cavity was built, processed, and tested with LEPP facilities at Cornell University. New techniques included half-cell heat treatment with yttrium for post-purification to RRR = 500, and vertical electropolishing the finished cavity.

 
 
RPAE001 On the Issue of Phasing of Undulators at the Advanced Photon Source undulator, brilliance, radiation, emittance 764
 
  • R.J. Dejus
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

Placing two collinear undulators in the 5.6-m-long straight sections at the Advanced Photon Source (APS) can answer the demand for increased brilliance. Whether longitudinal phasing needs to be taken into account for optimum spectral performance has been investigated. A comprehensive computer simulation study was completed to study the effect of the electron beam emittance, the magnetic field quality of the undulators, and the magnetic field strength (K value) on the spectral performance. For a zero-emittance beam, the radiation spectra exhibit strong interference that depends sensitively on the phase between the undulators. For a realistic APS-emittance beam and beam energy spread, the strong and phase-sensitive interference is substantially smoothed. A summary of the key findings including intensity losses due to unphased undulators is reported in this paper.

 
 
RPAE013 Laser System for Photoelectron and X-Ray Production in the PLEIADES Compton Light Source laser, scattering, photon, linac 1347
 
  • D.J. Gibson, C.P.J. Barty, S.M. Betts, K. Crane, I. Jovanovic
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

The PLEIADES (Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures) facility provides tunable short x-ray pulses with energies of 30-140 keV and pulse durations of 0.3 – 5 ps by scattering an intense, ultrashort laser pulse off a 35-75 MeV electron beam. Synchronization of the laser and electron beam is obtained by using a photoinjector gun, and using the same laser system to generate the electrons and the scattering laser. The Ti:Sapphire, chirped pulse amplification based 500 mJ, 50 fs, 810 nm scattering laser and the similar 300 μJ, 5 ps, 266 nm photoinjector laser systems are detailed. Additionally, an optical parametric chirped pulse amplification (OPCPA) system is studied as a replacement for part of the scattering laser front end. Such a change would significantly simplify the set-up the laser system by removing the need for active switching optics, as well as increase the pre-pulse contrast ratio which will be important when part of the scattering laser is used as a pump beam in pump-probe diffraction experiments using the ultrashort tunable x-rays generated as the probe.

 
 
RPAE015 High Energy, High Brightness X-Rays Produced by Compton Back Scattering at the Livermore PLEIADES facility laser, brightness, lattice, linac 1464
 
  • A.M. Tremaine, S.G. Anderson, S.M. Betts, K. Crane, D.J. Gibson, F.V. Hartemann, J.S. Jacob
    LLNL, Livermore, California
  • P. Frigola, J. Lim, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract no. W-7405-Eng-48.

PLEIADES (Picosecond Laser Electron Interaction for the Dynamic Evaluation of Structures) produces tunable 30-140 keV x-rays with 0.3-5 ps pulse lengths and 107 photons/pulse by colliding a high brightness electron beam with a high power laser. The electron beam is created by an rf photo-injector system, accelerated by a 120 MeV linac, and focused to 20 mm with novel permanent magnet quadrupoles. To produce Compton back scattered x-rays, the electron bunch is overlapped with a Ti:Sapphire laser that delivers 500 mJ, 80 fs, pulses to the interaction point. K-edge radiography at 115 keV on Uranium has verified the angle correlated energy spectrum inherent in Compton scattering and high-energy tunability of the Livermore source. Current upgrades to the facility will allow laser pumping of targets synchronized to the x-ray source enabling dynamic diffraction and time-resolved studies of high Z materials. Near future plans include extending the radiation energies to >400 keV, allowing for nuclear fluorescence studies of materials.

 
 
RPAE016 Smith-Purcell Radiation from a Charge Moving Above a Finite-Length Grating radiation, resonance, coupling, diagnostics 1496
 
  • A.S. Kesar, S.E. Korbly, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts
  • M. Hess
    IUCF, Bloomington, Indiana
  Funding: This work was supported by the Department of Energy, High Energy Physics, under contract DE-FG02-91ER40648.

Smith-Purcell radiation (SPR), emitted when a bunch is passing above a periodic structure, is characterized by a broadband radiation spectrum in which the wavelength depends on the observation angle. While various theoretical models agree on this dependence, a significant difference is introduced for the calculated radiated energy by the different approaches. We present two theoretical calculations of the SPR from a 2D bunch of relativistic electrons passing above a finite length grating. The first one uses the finite-difference time-domain approach and the second one uses an electric-field integral equation (EFIE) method. Good agreement is obtained between these two calculations. The results of these calculations are then compared with a formalism based on an infinite length grating in which a periodic boundary condition is rigorously applied. For gratings with less than approximately 50 periods, a significant error in the strength of the radiated field is introduced by the infinite grating approximation. This error disappears asymptotically as the number of periods increases. We are currently working on extending the EFIE model to the case of a three dimensional bunch moving above a finite-length grating.

 
 
RPAE017 Radially Polarized Ion Channel Laser ion, bunching, radiation, betatron 1526
 
  • R.A. Bosch
    UW-Madison/SRC, Madison, Wisconsin
  Radially polarized radiation is amplified by a free electron laser (FEL) in which the undulator is an ion channel with uniform density. For long betatron wavelengths and low gain per pass, the gain at a given distance from the axis is three-eighths the gain of a periodic ion channel laser with the same wiggler parameter. For amplification of short wavelengths by an ultrarelativistic electron beam, a uniform-density ion channel requires a much higher ion density than a periodic ion channel laser.  
 
RPAE018 Calculation of Reflection Matrix Elements of a Grating for Growing Evanescent Waves scattering, radiation, electromagnetic-fields 1616
 
  • V. Kumar, K.-J. Kim
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

Reflection matrix elements of a grating play an important role in the study of Smith-Purcell (SP) free-electron lasers (FELs). Especially, the matrix element e00, which couples the incident co-propagating evanescent wave to the outgoing co-propagating evanescent wave, is important for the evaluation of the gain of an SP FEL system.* We use the modal expansion method as well as the integral method and extend them to the case of growing evanescent waves. We present the results of numerical calculations for rectangular and sinusoidal gratings. We study the singularity of e00 and find that it is possible to get a simple formula for the location of singularity for the case of rectangular grating if we chose the eigenmodes of the groove as the basis set as done by Andrews et. al.**

*K.-J. Kim and S. B. Song, Nucl. Instrum. Methods Phys. Res. A 475, 158 (2001). **H. L. Andrews and C. A. Brau, Phys. Rev. ST Accel. Beams 7, 07070 (2004).

 
 
RPAE019 Positron Source from Betatron X-Rays Emitted in a Plasma Wiggler positron, plasma, radiation, wiggler 1625
 
  • D.K. Johnson, C.E. Clayton, C. Huang, C. Joshi, W. Lu, K.A. Marsh, W.B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • C.D. Barnes, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, C.L. O'Connell, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  In the E-167 plasma wakefield accelerator (PWFA) experiments in the Final Focus Test Beam (FFTB) at the Stanford Linear Accelerator Center (SLAC), an ultra-short, 28.5 GeV electron beam field ionizes a neutral column of Lithium vapor. In the underdense regime, all plasma electrons are expelled creating an ion column. The beam electrons undergo multiple betatron oscillations leading to a large flux of broadband synchrotron radiation. With a plasma density of 3x1017 cm-3, the effective focusing gradient is near 9 MT/m with critical photon energies exceeding 50 MeV for on-axis radiation. A positron source is the initial application being explored for these X-rays, as photo-production of positrons eliminates many of the thermal stress and shock wave issues associated with traditional Bremsstrahlung sources. Photo-production of positrons has been well-studied; however, the brightness of plasma X-ray sources provides certain advantages. In this paper, we present results of the simulated radiation spectra for the E-167 experiments, and compute the expected positron yield.  
 
RPAE020 Production of High Harmonic X-Ray Radiation from Non-linear Thomson at LLNL PLEIADES laser, scattering, radiation, focusing 1673
 
  • J. Lim, A. Doyuran, P. Frigola, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • S.G. Anderson, M. Betts, K. Crane, D.J. Gibson, F.V. Hartemann, A.M. Tremaine
    LLNL, Livermore, California
  Funding: US-DOE under contract no. DE-FG-98ER45693 and DE-FG03-92ER40693, and by LLNL under contract no. W-7405-Eng-48 and the LLNL ILSA program under contract LS04-001-B.

We describe an experiment for production of high harmonic x-ray radiation from Thomson backscattering of an ultra-short high power density laser by a relativistic electron beam at the PLEIADES facility at LLNL. In this scenario, electrons execute a “figure-8” motion under the influence of the high-intensity laser field, where the constant characterizing the field strength is expected to exceed unity: $aL=e*EL/m*c*ωL ≥ 1$. With large $aL$ this motion produces high harmonic x-ray radiation and significant broadening of the spectral peaks. This paper is intended to give a layout of the PLEIADES experiment, along with progress towards experimental goals.

 
 
RPAE021 Feasibility Study of a Laser Beat-Wave Seeded THz FEL at the Neptune Laboratory undulator, radiation, laser, beat-wave 1721
 
  • S. Reiche, C. Joshi, C. Pellegrini, J.B. Rosenzweig, S. Tochitsky
    UCLA, Los Angeles, California
  • G. Shvets
    The University of Texas at Austin, Austin, Texas
  Funding: The work was supported by the DOE Contract No. DE-FG03-92ER40727.

Free-Electron Laser in the THz range can be used to generate high output power radiation or to modulate the electron beam longitudinally on the radiation wavelength scale. Microbunching on the scale of 1-5 THz is of particular importance for potential phase-locking of a modulated electron beam to a laser-driven plasma accelerating structure. However the lack of a seeding source for the FEL at this spectral range limits operation to a SASE FEL only, which denies a subpicosecond synchronization of the current modulation or radiation with an external laser source. One possibility to overcome this problem is to seed the FEL with two external laser beams, which difference (beat-wave) frequency is matched to the resonant FEL frequency in the THz range. In this presentation we study feasibility of an experiment on laser beat-wave injection in the THz FEL considered at the UCLA Neptune Laboratory, where both a high brightness photoinjector and a two-wavelength, TW-class CO2 laser system exist. By incorporating the energy modulation of the electron beam by the ponderomotive force of the beat-wave in a modified version of the time-dependent FEL code Genesis 1.3, the performance of a FEL at Neptune is simulated and analyzed.

 
 
RPAE022 Improved Long Radius of Curvature Measurement System for FEL Mirrors laser, wiggler, optics, radiation 1787
 
  • J. Li, C. Sun, Y.K. Wu
    DU/FEL, Durham, North Carolina
  Funding: This work is supported by the U.S. AFOSR MFEL grant F49620-001-0370.

The 53.73 meter long Duke free electron laser (FEL) cavity consists of two concave mirrors with radius of curvature longer than 27 meters. A proper radius of curvature is designed to achieve an optimal and stable operation of the FEL. This requires accurate measurements of the cavity mirror's radius of curvature before its initial installation. Subsequent radius of curvature measurements are performed to ensure no significant deformation of the mirror occurs after a period of extensive use. A direct measurement based upon the geometric optics principles has been used at DFELL for years. Recently, we have significantly upgraded this measurement apparatus by utilizing a HeNe laser as the light source and a straight wire with a proper size as the object. In this paper we describe the details of the measurement setup and report the benefits of the recent upgrades. In addition, we report the improved data analysis technique and results of recent long radius of curvature measurements.

 
 
RPAE032 Femtosecond Laser-Electron Interaction in a Storage Ring Studied by Terahertz Radiation laser, radiation, dipole, storage-ring 2239
 
  • K. Holldack, S. Khan, T. Quast
    BESSY GmbH, Berlin
  • R. Mitzner
    Universität Muenster, Physikalisches Institut, Muenster
  Funding: This work was supported by the german Bundesministerium für Bildung und Forschung (BMBF).

The laser-induced energy modulation of relativistic electrons in the BESSY II storage ring was studied by temporal and spectral characterization of femtosecond far infrared (THz) pulses being emitted due to the fact that dispersive elements convert the energy modulation into a longitudinal density modulation. Bunch shapes down to 3 ps and phase noise effects as well as the length of the femtosecond density modulation and its temporal decay were measured. The THz diagnostics is crucial for the operation of the recently commissioned undulator based "femtosecond slicing" source at BESSY.

 
 
RPAE033 Commissioning Results from the BESSY II Femtoslicing Source laser, polarization, radiation, background 2309
 
  • S. Khan, K. Holldack, T. Kachel, T. Quast
    BESSY GmbH, Berlin
  • R. Mitzner
    Universität Muenster, Physikalisches Institut, Muenster
  Funding: Funded by the Bundesministerium für Bildung und Forschung and by the Land Berlin.

At the BESSY II storage ring, a source of sub-100 fs x-ray pulses with tunable polarization and excellent signal-to-background ratio has been constructed in 2004. This source is based on laser-induced energy modulation ("femtoslicing") and subsequent angular separation of the short-pulse x-rays emitted by an elliptical undulator. The paper reviews the layout of the source and reports on new insights and experimental results obtained while commissioning the source for user operation.

 
 
RPAE034 Storage Ring Fill Patterns for Femtoslicing Applications laser, radiation, injection, single-bunch 2327
 
  • S. Khan
    BESSY GmbH, Berlin
  Funding: Funded by the Bundesministerium für Bildung und Forschung and by the Land Berlin.

The generation of laser-induced ultrashort synchrotron radiation pulses ("femtoslicing") during user operation at the BESSY II storage ring requires to add several bunches with enhanced charge to the routinely used multibunch fill. The paper addresses these specialized fill patterns in view of beam stability against multibunch oscillations and ion effects, beam lifetime, and the effect of beam loading on the synchronous phase angles.

 
 
RPAE035 Orbit Stability at BESSY feedback, diagnostics, dipole, insertion 2366
 
  • R. Müller, J. Feikes, K. Holldack, P. Kuske
    BESSY GmbH, Berlin
  Funding: Funded by the Bundesministerium für Bildung und Forschung and by the Land Berlin.

Traditionally intrinsic component stability as well as perturbation source identification and suppression (like set-up modifications or feed-forward compensations) have been the preferred methods used to guarantee beam orbit stability for user operation at BESSY. Second focus of activity is the reliability of slow drift control and the high degree of beam position reproducibility maintained under frequently changed operation conditions. Along these lines an overview of the measures taken, the available diagnostic means as well as the achievements and shortcomings of the existing slow orbit feedback is given. Diagnostic capabilities of a fast BPM read-out and data distribution system give insight into the demands on a fast orbit feedback that could provide better operation flexibility and improved performance.

 
 
RPAE040 COD Correction at the PF and PF-AR by New Orbit Feedback Scheme feedback, insertion, insertion-device, dipole 2613
 
  • K. Harada, T. Obina
    KEK, Ibaraki
  • N. Nakamura, H. Sakai, H. Takaki
    ISSP/SRL, Chiba
  The eigen-vector method with a constraint condition is a new COD correction method that enables us to combine the local orbit correction at the insertion devices with the global COD correction by integrating the local one into the global one as the constraint condition using the Lagrange’s undetermined multiplier method. In order to achieve this method, we only use the new contrived response matrix for the global COD correction where the local correction is involved and done simultaneously. We have tested this correction scheme at the PF ring and the PF-AR. In the machine studies, the new orbit correction method is successfully demonstrated. The RMS COD of the constraint BPMs are sufficiently suppressed and, on the other hand, there is almost no large difference in the RMS COD of all the other BPMs between the new and ordinary methods.  
 
RPAE046 Operational Status at the PLS: Recent Improvements and Changes storage-ring, closed-orbit, injection, feedback 2923
 
  • E.S. Park, J. Choi, H.-S. Kang, M. Kim, E.-H. Lee, T.-Y. Lee
    PAL, Pohang, Kyungbuk
  PLS has been operated 10 years since 1994. A few improvements has been made to stabilize the reference orbit drifts caused by insertion devices and other sources: The control system has been upgraded to 20 bit capability from 12 bit. The slow global orbit feedback is employed routinely in the user run times. These improvements and the operational status changes will be presented in this report.  
 
RPAE061 Beam Loss Simulation Studies for ALS Top-Off Operation injection, simulation, radiation, storage-ring 3532
 
  • H. Nishimura, R.J. Donahue, D. Robin, C. Steier
    LBNL, Berkeley, California
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

The ALS is planning to operate with top-off injection at higher beam currents and smaller vertical beam size. As part of a radiation safety study for top-off, we carried out two kinds of tracking studies: (1) to confirm that the injected beam cannot go into users’ photon beam lines, and (2) to control the location of beam dump when the storage ring RF is tripped. (1) is done by tracking electrons from a photon beam line to the injection sector inversely by including the magnetic field profiles, varying the field strength with geometric aperture limits to conclude that it is impossible. (2) is done by tracking an electron with radiation in the 6-dim space for different combinations of vertical scrapers for the realistic lattice with errors.

 
 
RPAE065 Generation of Picosecond X-Ray Pulses in the ALS Using RF Orbit Deflection radiation, photon, storage-ring, synchrotron 3659
 
  • D. Robin, J.M. Byrd, P. Fischer, P.A. Heimann, D.H. Kim, S. Kwiatkowski, D. Li, F. Sannibale, C. Steier, W. Wan, W. Wittmer, A. Zholents
    LBNL, Berkeley, California
  Funding: This work was supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Materials Sciences Division of the U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.

A scheme is studied for producing ps length pulses of x-ray radiation from the Advanced Light Source (ALS) using two RF deflecting cavities. The cavities create vertical displacements of electrons correlated with their longitudinal position in the bunch. The two cavities separated by 180 degrees of vertical phase advance. This allows the vertical kick from one cavity to be compensated by the vertical kick of the other. The location of the cavities corresponds to the end of one straight section and the beginning of the following straight section. Halfway between the cavities a bending magnet source is located. The radiation from the bend can be compressed to ~1 ps in duration.

 
 
RPAE066 Terahertz Coherent Synchrotron Radiation from Femtosecond Laser Modulation of the Electron Beam at the Advanced Light Source laser, radiation, lattice, synchrotron 3682
 
  • J.M. Byrd, Z. Hao, M.C. Martin, D. Robin, F. Sannibale, R.W. Schoenlein, A. Zholents, M.S. Zolotorev
    LBNL, Berkeley, California
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

At the Advanced Light Source (ALS), the "femtoslicing" beamline is in operation since 1999 for the production of x-ray synchrotron radiation pulses with femtosecond duration. The mechanism used for generating the short x-ray pulses induces at the same time temporary structures in the electron bunch longitudinal distribution with very short characteristic length. Such structures emit intense coherent synchrotron radiation (CSR) in the terahertz frequency range. This CSR, whose measured intensity is routinely used as a diagnostics for the tune-up of the femtoslicing experiments, represents a potential source of terahertz radiation with very interesting features. Several measurements have been performed for its characterization and in this paper an updated description of the experimental results and of their interpretation is presented.

 
 
RPAE068 Very Short Bunches in MIT-Bates South Hall Ring optics, lattice, synchrotron, radiation 3768
 
  • D. Wang, dc. Cheever, M. Farkhondeh, W.A. Franklin, W. Graves, E. Ihloff, C. Tschalaer, D. Wang, D. Wang, F. Wang, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • B. Podobedov
    BNL, Upton, Long Island, New York
  Funding: Department of Energy

The study of ultra-short bunches in MIT SHR storage ring with very small momentum compactions is carried out. The ultra-short bunches are to greatly enhence the coherent radiation by many orders of magnitude. The ring lattice is resigned to reach very small momentum compaction factor down to 1·10-5 levels. The measurement is performed with the streak camera. The various associated issues are discussed.

 
 
RPAE069 Terahertz Coherent Synchrotron Radiation in the MIT-Bates South Hall Ring lattice, synchrotron, storage-ring, laser 3783
 
  • F. Wang, dc. Cheever, M. Farkhondeh, W.A. Franklin, W. Graves, E. Ihloff, C. Tschalaer, D. Wang, D. Wang, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • G.L. Carr, B. Podobedov
    BNL, Upton, Long Island, New York
  • F. Sannibale
    LBNL, Berkeley, California
  We investigate the terahertz coherent synchrotron radiation (CSR) potential of the South Hall Ring (SHR) at MIT-Bates Linear Accelerator Center. The SHR is equipped with a unique single cavity, 2.856 GHz RF system. The high RF frequency is advantageous for producing short bunch length and for having higher bunch current threshold to generate stable CSR. Combining with other techniques such as external pulse stacking cavity, femtosecond laser slicing, the potential for generating ultra-stable, high power, broadband terahertz CSR is very attractive. Beam dynamics issues related to short bunch length operation, and may associated with the high frequency RF system, such as multi-bunch instability are concerned. They could affect bunch length, bunch intensity and beam stability. The SHR is ideal for experimental exploration of these problems. Results of initial test of low momentum compaction lattice and bunch length measurements are presented and compared to expectations.  
 
RPAE073 Generating Picosecond X-Ray Pulses with Beam Manipulation in Synchrotron Light Sources synchrotron, photon, coupling, simulation 3898
 
  • W. Guo, M. Borland, K.C. Harkay, V. Sajaev, B.X. Yang
    ANL, Argonne, Illinois
  Funding: Work supported by U. S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38.

The length of x-ray pulses generated by storage ring light sources is usually tens of picoseconds. For example, the value is 40 ps rms at the Advanced Photon Source (APS). Methods of x-ray pulse compression are of great interest at the APS. One possible method, per Zholents et al., is to tilt the electron bunch with deflecting rf cavities.* Alternately, we found that the electron bunch can develop a tilt after application of a vertical kick in the presence of nonzero chromaticity. After slicing, the x-ray pulse length is determined by the tilt angle and the vertical beam size. In principal, sub-picosecond pulses can be obtained at APS. To date we have observed 6 ps rms visible light pulses with a streak camera. Efforts are underway to attempt further compression of the x-ray pulse and to increase the brilliance. This method can be easily applied to any storage ring light sources to generate x-ray pulses up to two orders of magnitude shorter than the electron bunch length. In this paper, we will present the theory of bunch tilt, particularly the synchrobetatron coupling and decoherence beam dynamics, and the simulation and the experimental results will also be shown as verification.

*A. Zholents et al., NIM A 425, 385(1999).

 
 
RPAE076 The Commission of Hefei Light Source After Reconstruction injection, closed-orbit, octupole, radiation 3967
 
  • H. Xu, H. He, W. Li, G. Liu, L. Liu, S. Shang, B. Sun, L. Wang
    USTC/NSRL, Hefei, Anhui
  After the new four-kicker injection bump system was mounted, it was found that the magnetic field of four–kicker magnet through the same pulse current is different each other, the reason is which the width of pulse magnet fields is not same, so the four-kickers can not form completely local bump, and produce large global orbit distortion,and lead to beam loss. At last we found that the films of ceramic chambers were not plated evenly. The new rf system have two low level control circle circuits, which are the frequency and amplitude automatic adjustment systems. Because the energy of injection electron beam is 200MeV, and radiation damping is weak, so the gain of amplitude circuit was adjusted to the small value not to disturb beam.The beam load is large,and Robinson instability happen easily, so the small detune angle is preset. The Octupoles were inserted in ring for damping instability, and over compensated chromaticity was adjusted.Superconductor wiggler bring the variation of beta function, and the beam life time decreased from 8 hours to about 3 hours. By adjusting the beta functions close to situation ago, the beam lifetime was improved.  
 
RPAE078 Commissioning of SAGA Light Source linac, vacuum, injection, septum 4021
 
  • T. Tomimasu, Y. Iwasaki, S. Koda, Y. Takabayashi, K. Yoshida
    Saga Synchrotron Light Source, Industry Promotion Division, Saga City
  • H. Ohgaki
    Kyoto IAE, Kyoto
  • H. Toyokawa, M.Y. Yasumoto
    AIST, Ibaraki
  The SAGA Light Source (SAGA-LS) consists of a 250-MeV electron linac injector and an eight-hold symmetry 1.4-GeV storage ring with eight double-bend (DB) cell and eight 2.93-m long straight sections. The DB cell structure with a distributed dispersion system was chosen to produce a compact ring of 75.6-m long circumference. The machine construction begun September 29, 2003. The ring magnets of steel laminated structure, vacuum chambers made of aluminum alloy, pumping systems and four temperature controlled cooling water systems for the linac accelerating wave guides etc. were installed in March, 2004. The injector, a 500-MHz ring rf damped cavity, rf klystrons, beam transport systems for injection and their controlled systems were installed in July, 2004. The commissioning begun August 25, 2004. A 250-MeV beam was accelerated on September 29. The beam size is 1-mm in diameter and the energy spread is 0.8 % (FWHM). The first revolution of 250-MeV beam around the ring took place October 22. Beam was stored on November 12. The commissioning continues for beam storage and ramping to 1.4-GeV. We report a brief description of SAGA light source and early commissioning activities.  
 
RPAE085 ELETTRA Present and Future Upgrades booster, storage-ring, feedback, undulator 4170
 
  • C.J. Bocchetta, D. Bulfone, G. D'Auria, G. De Ninno, B. Diviacco, A. Fabris, R. Fabris, M. Ferianis, A. Gambitta, F. Iazzourene, E. Karantzoulis, M. Lonza, F.M. Mazzolini, M. Svandrlik, L. Tosi, R. Visintini, D.Z. Zangrando
    ELETTRA, Basovizza, Trieste
  During the last year, the 3rd generation synchrotron light source ELETTRA has benefitted from several upgrades which have been implemented in the frame of a project to enhance the quality of the light source. The superconducting 3rd harmonic cavity, the feedbacks, the realignment of the whole ring and other improved devices have allowed to further, significantly optimize the beam stability and lifetime, as well as the operability and uptime of the facility. At the same time two large scale projects are underway that will change the perspectives of the whole laboratory, namely the full energy booster injector and the single pass X-ray FEL FERMI@Elettra, based on the existing linac. Their status will be presented here together with the overview of the existing light source.  
 
RPAE086 Observation of Coherent Synchrotron Radiation at NewSUBARU radiation, synchrotron, synchrotron-radiation, storage-ring 4188
 
  • S. Hashimoto, A. Ando
    University of Hyogo, Laboratory of Advanced Science and Technology for Industry (LASTI), Kamigori-cho, Ako-gun, Hyogo
  • Y. Shoji
    LASTI, Ako-gun, Hyogo
  • T. Takahashi
    KURRI, Osaka
  Coherent Synchrotron Radiation from a short electron bunch in a storage ring was observed at NewSUBARU. The energy of electron was 1GeV. The ring was operated with quasi-isochronous mode. The linear momentum compaction factor was smaller than 2 X 10-5 and the bunch length was shorter than 5ps (FWHM). We observed an extremely strong radiation from the weak electron beam, 1μA per bunch.  
 
RPAP006 X-Band Linac Beam-Line for Medical Compton Scattering X-Ray Source laser, photon, linac, scattering 994
 
  • K. Dobashi
    NIRS, Chiba-shi
  • M. Akemoto, H. Hayano, T. Higo, J.U. Urakawa
    KEK, Ibaraki
  • F. Ebina, A. Fukasawa, T. Kaneyasu, H. Ogino, F. Sakamoto, M. Uesaka, Y. Yamamoto
    UTNL, Ibaraki
  Compton scattering hard X-ray source for 10~80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U. Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard ( 10-80 keV) X-rays with the intensities of 108-10 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at the beam dump by adopting the deceleration of electrons after the Compton scattering. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2.5 J/10 ns is 107 photons/RF-pulse (108 photons/sec in 10 pps). X-band beam line for the demonstration is under commissioning. We also design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). The construction of the whole system starts. X-ray generation and medical application will be performed in this year.  
 
RPAP008 The CBS–The Most Cost Effective and High Performance Carbon Beam Source Dedicated for a New Generation Cancer Therapy ion, extraction, synchrotron, injection 1108
 
  • M. Kumada
    NIRS, Chiba-shi
  • B.I. Grishanov, E.B. Leivichev, V.V. Parkhomchuk, F.V. Podgorny, S. Rastigeev, V.B. Reva, A.N. Skrinsky, V.A. Vostrikov
    BINP SB RAS, Novosibirsk
  A Carbon ion beam is a superior tool to x-rays or a proton beam in both physical and biological doses in treating a cancer. A Carbon beam has an advantage in treating radiation resistant and deep-seated tumors. Its radiological effect is of a mitotic independent nature. These features improve hypofractionation, typically reducing the number of irradiations per patient from 35 to a few. It has been shown that a superior QOL(Quality Of Life) therapy is possible by a carbon beam.The only drawback is its high cost. Nevertheless, tens of Prefectures and organizations are eagerly considering the possibility of having a carbon ion therapy facility in Japan. Germany, Austria, Italy, China, Taiwan and Korea also desire to have one.A carbon beam accelerator of moderate cost is about 100 Million USD. With the "CBS" design philosophy, which will be described in this paper, the cost could be factor of 2 or 3 less, while improving its performance more than standard designs. Novel extraction techniques, a new approach to a high intensity beam, a new scanning method of a superμbeam and an extremely light weight carbon rotating gantry will be presented.This new CBS will have an impact on the medical accelerator community.  
 
RPAP010 Development of Femtosecond and Attosecond Pulse Radiolysis by Using Laser Photocathode RF Gun S-Band Electron Linac laser, linac, gun, cathode 1198
 
  • Y. Yoshida, T. Kondo, J. Yang
    ISIR, Osaka
  Funding: Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science.

Femtosecond pulse radiolysis system based on linear accelerator was developed in Osaka University for study of radiation-induced ultra fast physical and chemical reactions. 35 MeV single electron pulse with pulse width of 100 fs was generated by using a laser photocathode rf gun s-band linac with a magnet pulse compression system. Femtosecond laser synchronized with the linac was used as analyzing light. Transient absorption was measured by the equivalent velocity spectroscopy which was a new method to get high time-resolution. Also, we have started the preliminary experiment on atosecond pulse radiolysis The double decker beam which is a new concept to realize the twin linac by using one linac will be used.

 
 
RPAP011 Technical Development of Profile Measurement for the Soft X-Ray Via Compton Backward Scattering laser, scattering, background, quadrupole 1260
 
  • T. Saito, Y. Hama, K. Hidume, S. Minamiguchi, A. Oshima, D. Ueyama, M. Washio
    RISE, Tokyo
  • H. Hayano, J.U. Urakawa
    KEK, Ibaraki
  • S. Kashiwagi
    ISIR, Osaka
  • R. Kuroda
    AIST, Tsukuba, Ibaraki
  A compact X-ray source is called for such various fields as material development, biological science, and medical treatment. At Waseda University, we have already succeeded to generate the soft X-ray of the wavelength within so-called water window region (250-500eV) via Compton backward scattering between 1047nm Nd:YLF laser and 4.2MeV high quality electron beam. Although this method equips some useful characters, e.g. high intensity, short pulse, energy variableness, etc, the X-ray generating system is compact enough to fit in tabletop size. In the next step, there rises two principal tasks, that is, to make the soft X-ray intensity higher, and to progress X-ray profile measurement techniques as preliminary experiments for biomicroscopy. Specifically, we utilize two-pass amp for the former, and irradiate X-ray to a resist film which is previously exposed by UV lamp or get images with X-ray CCD for the latter. In this conference, we will show the experimental results and some future plans.  
 
RPAP012 Dual Energy X-Ray CT by Compton Scattering Hard X-Ray Source scattering, simulation, linac, photon 1291
 
  • M. Uesaka, T. Kaneyasu
    UTNL, Ibaraki
  • K. Dobashi, M. Torikoshi
    NIRS, Chiba-shi
  We have developed a compact Compton scattering hard X-ray source at Nuclear Engineering Research Laboratory, University of Tokyo. The compact hard X-ray source can produce tunable monochromatic hard X-rays. The monochromatic hard X-rays are required in large field of medical and biological applications. We are planning to perform dual-energy X-ray CT, which enables us to measure atomic number Z distribution and electron density re distribution in a material. The hard X-ray source has an advantage to perform dual-energy X-ray CT. The X-ray energy can be changed quickly by introducing a fundamental frequency and a second harmonic frequency lasers. This quick energy change is indispensable to medical imaging and very difficult in a large SR light source and others. The information on the atomic number and electron density will be used for treatment plan in radiotherapy as well as for identification of materials in a nondestructive test. We examined applicability of the dual-energy X-ray CT for atomic number measurement for low to medium Z elements (Z=30) by considering the X-ray profile generated by Compton scattering. Details of the numerical simulations and plans of the dual-energy X-ray CT will be reported in the conference.  
 
RPAP015 Modeling of Internal Injection and Beam Dynamics for High Power RF Accelerator simulation, cathode, injection, focusing 1419
 
  • M.A. Tiunov, V. Auslender, M.M. Karliner, G.I. Kuznetsov, I. Makarov, A.D. Panfilov, V.V. Tarnetsky
    BINP SB RAS, Novosibirsk
  Funding: The work is supported by ISTC grant #2550.

A new high power electron accelerator for industrial applications is developed in Novosibirsk. Main parameters of the accelerator are: operating frequency of 176 MHz, energy of electrons of 5 MeV, average beam power up to 300 kW. The accelerator consists of a chain of accelerating cavities, connected by the on-axis coupling cavities with coupling slots in the walls. A triode RF gun on the base of grid-cathode unit placed on the wall of the first accelerating cavity is used for internal injection of electrons. The paper presents the results of modeling and optimization of the accelerating structure, internal injection, and beam dynamics.

 
 
RPAP016 High Power Electron Accelerator Prototype injection, cathode, gun, feedback 1502
 
  • V.O. Tkachenko, V. Auslender, V.G. Cheskidov, G.I. Korobeynikov, G.I. Kuznetsov, A.N. Lukin, I. Makarov, G. Ostreiko, A.D. Panfilov, A. Sidorov, V.V. Tarnetsky, M.A. Tiunov
    BINP SB RAS, Novosibirsk
  Funding: The work is supported by ISTC grant #2550.

In recent time the new powerful industrial electron accelerators appear on market. It caused the increased interest to radiation technologies using high energy X-rays due to their high penetration ability. However, because of low efficiency of X-ray conversion for electrons with energy below 5 MeV, the intensity of X-rays required for some industrial applications can be achieved only when the beam power exceeds 300 kW. The report describes a project of industrial electron accelerator ILU-12 for electron energy up to 5 MeV and beam power up to 300 kW specially designed for use in industrial applications. On the first stage of work we plan to use the existing generator designed for ILU-8 accelerator. It is realized on the GI-50A triode and provides the pulse power up to 1.5-2 MW and up to 20-30 kW of average power. In the report the basic concepts and a condition of the project for today are reflected.

 
 
RPAP017 Industrial Electron Accelerators Type ILU extraction, vacuum, cathode, shielding 1572
 
  • V. Auslender, A.A. Bryazgin, V.G. Cheskidov, B.L. Faktorovich, V. Gorbunov, I.V. Gornakov, V.E. Nekhaev, A.D. Panfilov, A.V. Sidorov, V.O. Tkachenko, A.F.A. Tuvik, L.A. Voronin
    BINP SB RAS, Novosibirsk
  The report describes the electron accelerators of ILU series covering the energy range from 0.5 to 5 MeV with beam power up to 50 kW. The pulse linear accelerators type ILU are developed since 1970 in Budker institute of Nuclear Physics and are supplied to the industry. The ILU machines are purposed for wide application in various technological processes and designed for long continuous and round-the-clock work in industrial conditions. A principle of acceleration of electrons in the gap of HF resonator is used in the ILU machines. The HF resonator has toroidal form. The electron gun is placed in one of the protruding electrodes forming the accelerating gap of the resonator. The resonator is fed from HF autogenerator realized on the industrial triode, the feedback signal is given from the resonator. The absence of outer beam injection and usage of self-excited HF generator simplify the design of accelerator and ensure its reliable operation.  
 
RPAP018 Identification of Nano-Objects in Substances by Using of X-Ray Electron Radiation radiation, photon, diagnostics, polarization 1610
 
  • V.K. Grishin
    MSU, Moscow
  Funding: Russian Foundation for Basic Researches, grant 03-02-16587.

Using opportunity of X-ray emission, arising at process of fast charge interaction with media atomic electrons, for nano-object discovery and diagnostics in substances is discussed. This kind of of X-ray emission termed as polarization bremsstrahlung radiation (PB) depends very strongly on media structure. As result spectra of PB in a media containing nano-inhomogeneities (as fullerenes, nanotubes, composite structures as fullerites) reflex structural characteristics of last ones. Fullerenes in carbon soot as example of an amorphous substance with mentioned structure inhomogeneities are considered. It is shown that spectra of PB on fullerenes contain a series of oscillations which give the valuable information about single- ore multilayers fullerene structures. The main peak of emission is placed in energy area of PB photons less than 1-1.5 keV. Here PB obtains a coherent character due to which one PB intensity is very high because it becomes to proportional square of all fullerene electrons number. Due to PB intensity depends weakly enough on observation angle, that permits to pick up PB signal from traditional bremsstrahlung radiation, and to facilitate measurement conditions.

 
 
RPAP021 A Portable Electron Radiography System quadrupole, proton, collimation, permanent-magnet 1715
 
  • F.E. Merrill, C.L. Morris
    LANL, Los Alamos, New Mexico
  • K. Folkman, F. Harmon, A.W. Hunt, B. King
    ISU, Pocatello, Idaho
  The technique of charged particle radiography has been developed and proven with 800 MeV protons at LANSCE and 24 GeV protons at the AGS. Recent work at Los Alamos National Laboratory in collaboration with the Idaho Accelerator Center has extended this diagnostic technique to electron radiography through the development of an inexpensive and portable electron radiography system. This system has been designed to use 30 MeV electrons to radiograph thin static and dynamic systems. The system consists of a compact 30 MeV pulsed electron linear accelerator coupled to a quadrupole lens magnifier constructed from permanent magnet quadrupoles. The design features and operational characteristics of this radiography system are presented as well as the radiographic performance parameters.  
 
RPAP024 The ORNL Multicharged Ion Research Facility (MIRF) High Voltage Platform Project ion, ion-source, permanent-magnet, beam-transport 1853
 
  • F.W. Meyer, M.E. Bannister, J.W. Hale, J.W. Johnson
    ORNL, Oak Ridge, Tennessee
  • D. Hitz
    CEA Grenoble, Grenoble
  Funding: This research was sponsored by the Office of Basic Energy Sciences, and the Office of Fusion Energy Sciences of the U.S. DOE under contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.

We report on initial testing and implementation of a new high voltage platform recently installed at the ORNL MIRF. The platform is powered by a 250 kV, 30 kVA isolation transformer and features an all permanent magnet Electron Cyclotron Resonance (ECR) ion source, designed and fabricated at CEA/Grenoble, that utilizes microwave power levels of up to 750W in the frequency range 12.75 – 14.5 GHz to provide intense dc beams of singly and multiply charged ions for acceleration to energies up to 270 x q keV. The primary application of these ion beams is to study fundamental collisional interactions* of multicharged ions with electrons, atoms, and surfaces. More applied investigations in the area of ion implantation,** and ion beam development for use in semiconductor doping operations are carried out as well. Design details of the HV platform and the associated beamline-switchyard will be presented at the conference, together with performance characteristics of the all permanent magnet ECR source, of the beam transport from ion source to end-station, and of a novel electrostatic spherical sector beam switcher for directing beam to the various on-line experiments.

*F.W . Meyer, Trapping Highly Charged Ions: Fundamentals and Applications, J. Gillaspy, ed., Nova Science Pub., New York, 2000, pp. 117-164. **F. W. Meyer et al., AIP Conf. Proc. 635, p. 125 (2002).

 
 
RPAP025 A 7MeV S-Band 2998MHz Variable Pulse Length Linear Accelerator System gun, linac, vacuum, power-supply 1895
 
  • M. Hernandez, H. Deruyter, D. Skowbo, R.R. Smith
    Accuray, Inc, Mountain View, California
  • A.V. Mishin, A.J. Saverskiy
    AS&E, Billerica, Massachusetts
  American Science and Engineering High Energy Systems Division (AS&E HESD) has designed and commissioned a variable pulse length 7 MeV electron accelerator system. The system is capable of delivering a 7 MeV electron beam with a pulse length of 10 nS FWHM and a peak current of 1 ampere. The system can also produce electron pulses with lengths of 20, 50, 100, 200, 400 nS and 3 uS FWHM with corresponding lower peak currents. The accelerator system consists of a gridded electron gun, focusing coil, an electrostatic deflector system, Helmholtz coils, a standing wave side coupled S-band linac, a 2.6 MW peak power magnetron, an RF circulator, a fast toroid, vacuum system and a PLC/PC control system. The system has been operated at repetition rates up to 250pps. The design, simulations and experimental results from the accelerator system are presented in this paper.  
 
RPAP027 Portable X-Band Linear Electron Accelerators for Radiographic Applications radiation, linac, coupling, injection 1985
 
  • A.J. Saverskiy, H. Deruyter, M. Hernandez, A.V. Mishin, D. Skowbo
    AS&E, Billerica, Massachusetts
  The MINAC series portable linear electron accelerator systems designed and manufactured at American Science and Engineering, Inc. High Energy Systems Division (AS&E HESD) are discussed in this paper. Each system can be configured as either an X-ray or electron beam source. The powerful 4 MeV and 6 MeV linacs powered by a 1,5 MW magnetron permit operation in a dose rate range from 100 R/min at 80 cm to 600 R/min at 80 cm. Each MINAC is a self-contained source with radiation leakage outside of the X-ray head less than 0,1% of the maximum dose. Along with these systems a 1 MeV ultra compact MINAC has been successfully tested. The unit is available with radiation leakage less then 0.01% and permits producing X-ray beam in an energy range (12) MeV at a high output dose rate. Design and experimental parameters are presented. The common and system specific features are also discussed.  
 
RPAP033 Investigation of X-Ray Harmonics of the Polarized Inverse Compton Scattering Experiment at UCLA laser, photon, scattering, permanent-magnet 2303
 
  • A. Doyuran, R.J. England, C. Joshi, J. Lim, J.B. Rosenzweig, S. Tochitsky, G. Travish, O. Williams
    UCLA, Los Angeles, California
  Funding: U.S. Dept. of Energy grant DE-FG03-92ER40693.

An Inverse Compton Scattering (ICS) experiment, which will investigate nonlinear properties of scattering utilizing a terawatt CO2 laser system with various polarizations, is ongoing at the UCLA Neptune Laboratory. When the normalized amplitude of the incident laser’s vector potential a0 is larger than unity the scattering occurs in the nonlinear region; therefore, higher harmonics are also produced. ICS can be used, e.g., for a polarized positron source by striking a thin target (such as tungsten) with the polarized X-rays. As such, it is critical to demonstrate the production of polarized scattered photons and to investigate the ICS process as it enters the nonlinear regime. We present the description of the experimental set up and equipment utilized, including diagnostics for electron and photon beam detection. We present the current status of the experiment.

 
 
RPAP034 Use Recirculator "SALO" in the Mode of the Neutron Source target, alignment, injection, emittance 2354
 
  • I.S. Guk, A. Dovbnya, S.G. Kononenko, F.A. Peev, A.S. Tarasenko
    NSC/KIPT, Kharkov
  • J.I.M. Botman, M.J. Van der Wiel
    TUE, Eindhoven
  The opportunity of use developed in NSC KIPT recirculator SALO* with superconducting accelerating structure TESLA for reception of intensive neutron streams surveyed. As an injector it is supposed to use RF-gun with superconducting accelerating structure. An electron beam with the peak energy 130 ??? is transported on a target located apart of 100 m from recirculator. System of the focusing are designed allowing to gain on a target the required density of a beam. Tolerances on precision of an alignment of magnetooptical devices are calculated.

*I. S. Guk, A. N. Dovbnya, S. G. Kononenko, A. S. Tarasenko, M. van der Wiel, J. I. M. Botman, NSC KIPT Accelerator on Nuclear and High Energy Physics, Proceedings of EPAC 2004, Lucerne, Switzerland, p.761-764.

 
 
RPAP035 Photonuclear and Radiation Effects Testing with a Refurbished 20 MeV Medical Electron Linac linac, radiation, photon, target 2363
 
  • T. Webb, L.C. DeVeaux, F. Harmon, J.E. Petrisko, R.J. Spaulding
    IAC, Pocatello
  • R. Assink
    Sandia National Laboratories, Albuquerque, New Mexico
  • W. Beezhold
    ISU, Pocatello, Idaho
  An S-band 20 MeV electron linear accelerator formerly used for medical applications has been recommissioned to provide a wide range of photonuclear activation studies as well as various radiation effects on biological and microelectronic systems. Four radiation effect applications involving the electron/photon beams are described. Photonuclear activation of a stable isotope of oxygen provides an active means of characterizing polymer degradation. Biological irradiations of microorganisms including bacteria were used to study total dose and dose rate effects on survivability and the adaptation of these organisms to repeated exposures. Microelectronic devices including bipolar junction transistors (BJTs) and diodes were irradiated to study photocurrent from these devices as a function of peak dose rate with comparisons to computer modeling results. In addition, the 20 MeV linac may easily be converted to a medium energy neutron source which has been used to study neutron damage effects on transistors.  
 
RPAP036 A Compact 5 MeV S-Band Electron Linac Based X-Ray Source for Industrial Radiography linac, target, collimation, insertion 2428
 
  • L. Auditore, R.C. Barnà, D. De Pasquale, U. Emanuele, A. Trifirò, M. Trimarchi
    INFN & Messina University, S. Agata, Messina
  • A. Italiano
    INFN - Gruppo Messina, S. Agata, Messina
  A compact and reliable X-ray source, based on a 5 MeV, 1 kW, S-band electron linac, has been set up at the Dipartimento di Fisica, Universit\‘a di Messina. This source, coupled with a GOS scintillator screen and a CCD camera, represents an innovative transportable system for industrial radiography and X-ray tomography. Optimization of the parameters influencing the e-gamma conversion and the X-ray beam characteristics have been studied by means of the MCNP-4C2 code. The converter choice is the result of the study of the e-gamma conversion performances for different materials and materials thicknesses. Also the converter position with respect to the linac exit window was studied. The chosen converter consists in a Ta-Cu target inserted close to the linac window. The Cu layer acts as a filter both on the electrons from the source and on the low energy X-rays. The X-ray beam angular profile was studied by means of GafChromic films with and without collimation. In the final source project, a collimation system provides a 14 cm diameter X-ray spot at the sample position and first radiographyc results were obtained by inspecting different density materials and thicknesses.  
 
RPAP038 An Advantage of the Equivalent Velocity Spectroscopy for Femtsecond Pulse Radiolysis laser, gun, linac, emittance 2533
 
  • T. Kondoh, T. Kozawa, S. Tagawa, T. Tomosada, J. Yang, Y. Yoshida
    ISIR, Osaka
  Funding: Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science.

For studies of electron beam induced ultra-fast reaction process, femtosecond(fs) pulse radiolysis is under construction. To realize fs time resolution, fs electron and analyzing light pulses and their jitter compensation system are needed. About a 100fs electron pulse was generated by a photocathode RF gun linac and a magnetic pulse compressor. Synchronized Ti: Sapphire laser have a puleswidth about 160fs. And, it is significant to avoid degradation of time resolution caused by velocity difference between electron and analyzing light in a sample. In the ‘Equivalent velocity spectroscopy’ method, incident analyzing light is slant toward electron beam with an angle associated with refractive index of sample. Then, to overlap light wave front and electron pulse shape, electron pulse shape is slanted toward the direction of travel. As a result of the equivalent velocity spectroscopy for hydrated electrons, using slanted electron pulse shape, optical absorption rise time was about 1.4ps faster than normal electron pulse shape. Thus, the 'Equivalent velocity spectroscopy’ is effective for femtosecond pulse radiolysis.

 
 
RPAP043 Beam-Based Alignment in the RHIC eCooling Solenoids ion, alignment, quadrupole, proton 2771
 
  • P. Cameron, I. Ben-Zvi, W.C. Dawson, J. Kewisch, V. Litvinenko, Y. Luo, W.W. MacKay, C. Montag, J. Niedziela, V. Ptitsyn, T. Satogata, C. Schultheiss, V. Yakimenko
    BNL, Upton, Long Island, New York
  Funding: U.S. DOE.

Accurate alignment of the electron and ion beams in the RHIC electron cooling solenoids is crucial for well-optimized cooling. Because of the greatly differing rigidities of the electron and ion beams, to achieve the specified alignment accuracy it is required that transverse magnetic fields resulting from imperfections in solenoid fabrication be down by five orders of magnitude relative to the pure solenoid fields. Shimming the solenoid field to this accuracy might be accomplished by survey techniques prior to operation with beam, or by methods of beam-based alignment. We report on the details of a method of beam-based alignment, as well as the results of preliminary measurements with the ion beam at RHIC

 
 
RPAP047 DAQ System of BPM and BCT for the BEPCII Linac linac, positron, pick-up, monitoring 2980
 
  • J. Cao, Q. Ye
    IHEP Beijing, Beijing
  Following the BEPCII upgrade, total about 19 BPM and 12 BCT have been newly installed in the BEPCII Linac. Also, a set of distributed control system based on EPICS architecture has been built, and the BPM and BCT system are merged into the new control system for the data acquisition. In order to reduce the effects of RF noise, a special gated integrator was used to measure the beam current. In this paper we will describe the DAQ system of BPM and BCT including calibrations in detail.  
 
RPAT005 Beam Diagnostics for the J-PARC Main Ring Synchrotron beam-losses, proton, pick-up, target 958
 
  • T. Toyama, D.A. Arakawa, Y. Hashimoto, S. Lee, T. Miura, S. Muto
    KEK, Ibaraki
  • N. Hayashi, J. Kishiro, R. Toyokawa
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  Beam diagnostics: beam intensity monitors (DCCT, SCT, FCT, WCM), beam position monitors (ESM), beam loss monitors (proportional chamber, air ion chamber), beam profile monitors (secondary electron emission, gas-sheet) have been designed, tested, and will be installed for the Main Ring synchrotron of J-PARC (Japan Proton Accelerator Research Complex). This paper describes the basic design principle and specification of each monitor, with a stress on how to cope with high power beam (average circulation current of ~12 A) and low beam loss operation (less than 1 W/m except a collimator region). Some results of preliminary performance test using present beams and a radiation source will be reported.  
 
RPAT027 Tomographic Measurement of Longitudinal Emittance Growth Due to Stripping Foils emittance, ion, booster, heavy-ion 2000
 
  • C. Montag, L. Ahrens, P. Thieberger
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the US Department of Energy.

During beam acceleration at the Brookhaven accelerator complex, heavy ions are stripped off their electrons in several steps. Depending on the properties of the stripping foils, this process results in an increased energy spread and therefore longitudinal emittance growth. A tomographic phase space reconstruction technique has been applied to quantify the associated emittance growth for different stripping foil materials.

 
 
RPAT032 An Ionization Profile Monitor for the Tevatron vacuum, ion, injection, collider 2227
 
  • A. Jansson, M. Bowden, K. Bowie, A. Bross, R. Dysert, T. Fitzpatrick, R. Kwarciany, C. Lundberg, H. Nguyen, C.H. Rivetta, D. Slimmer, L. Valerio, J.R. Zagel
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. Department of Energy.

Primarily to study emittance blowup during injection and ramping, an ionization profile monitor has been developed for the Tevatron. It is based on a prototype installed in the Main Injector, although with extensive modifications. In particular, the electromagnetic shielding has been improved, the signal path has been cleaned up, and provisions have been made for an internal electron source. Due to the good Tevatron vacuum, a local pressure bump is introduced to increase the primary signal, which is then amplified by a microchannel plate and detected on anode strips. For the DAQ, a custom ASIC developed for the CMS experiment is used. It is a combined charge integrator and digitizer, with a sensitivity of a few fC, and a time-resolution that allows single bunch measurement. Digitization is done in the tunnel to reduce noise. Preparations for detector installation were made during the long 2004 shutdown, with the installation of magnets, vacuum chambers, vacuum pumps and cabling. The actual detector will be installed sometime during the spring fo 2005. This paper describes the design of the detector and associated electronics and presents various bench test results.

 
 
RPAT038 Diagnostic for Electron Clouds Trapped in Quadrupoles quadrupole, simulation, diagnostics, proton 2547
 
  • R.J. Macek, A. A. Browman
    TechSource, Santa Fe, New Mexico
  Funding: Work supported by a DOE SBIR Phase I grant DE-FG02-04ER84105.

Simulations have indicated that electron clouds generated by beam-induced multipactor can be trapped in the mirror-like fields of magnetic quadrupoles and thereby contribute significantly to the electron cloud buildup in high intensity accelerators and storage rings. This could be the most important source of electrons driving the two-stream (e-p) instability at the Los Alamos PSR and may also play a significant role in electron cloud effects at some of the new high intensity accelerator projects. We will describe the physics design and optimization of an electron-sweeping detector designed to measure the trapped electrons at various times after the beam pulse has passed. The instrument can also serve as an electro-magnetically shielded detector providing a signal obtained from electrons striking the wall during the passage of beam bunches.

 
 
RPAT039 Feasibility Study of Using an Electron Beam for Profile Measurements in the SNS Accumulator Ring proton, SNS, simulation, vacuum 2586
 
  • A.V. Aleksandrov, S. Assadi, S.M. Cousineau, V.V. Danilov, S. Henderson, M.A. Plum
    ORNL, Oak Ridge, Tennessee
  • P.V. Logatchev, A.A. Starostenko
    BINP SB RAS, Novosibirsk
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

The design goal for the SNS ring is to accumulate 2·1014 protons per 1ms pulse at a 60Hz repetition rate. Achieving the design beam intensity with acceptable losses is a challenging task, which could be tackled more easily if reliable measurements of the beam profile in the ring are available. The high power density of the beam precludes the use of conventional wire scanners or harps and therefore non-interceptive types of profiles measurements are required. The electron beam probe method was suggested for measuring profiles in high power beams. In this method, deflection of a low energy electron beam by the collective field of the high intensity beam is measured. The charge density in the high intensity beam can be restored under certain conditions or estimated by various mathematical techniques. We studied the feasibility of using the electron beam probe for the SNS accumulator ring using computer simulations of the diagnostic setup. A realistic electron gun model and realistic proton beam distributions were used in the simulations. Several profile calculation techniques were explored and the results are reported in this paper.

 
 
RPAT047 Preliminary Design of a Femtosecond Oscilloscope laser, photon, interaction-region, electromagnetic-fields 2944
 
  • E.D. Gazazyan, K.A. Ispirian, A.T. Margaryan
    YerPhI, Yerevan
  • D.K. Kalantaryan
    YSU, Yerevan
  • E.M. Laziev
    CANDLE, Yerevan
  The calculations on motion of electrons in a finite length electromagnetic field of linearly and circularly polarized laser beams have shown that one can use the transversal deflection of electrons on a screen at a certain distance after the interaction region for the measurement of the length and longitudinal particle distribution of femtosecond bunches. In this work the construction and preliminary parameters of various parts of a device that may be called femtosecond oscilloscope are considered. The influence of various factors, such as the energy spread and size of the electron bunches, are taken into account. For CO2 laser intensity 1016 W/cm2 and field free drift length 1m the deflection is 5.3 and 0.06 cm, while the few centimeters long interaction length between 2 mirrors requires assembling accuracy 6 mm and 1.3 micron for 20 MeV to 50 keV, respectively.  
 
RPAT049 Numerical Studies on the Electro-Optic Sampling of Relativistic Electron Bunches laser, resonance, lattice, simulation 3070
 
  • S. Casalbuoni, H. Schlarb, B. Schmidt, B. Steffen
    DESY, Hamburg
  • P. Schmüser, A. Winter
    Uni HH, Hamburg
  Ultraviolet and X ray free electron lasers require sub-picosecond electron bunches of high charge density. Electro-optic sampling (EOS) is a suitable diagnostic tool for resolving the time structure of these ultrashort bunches. The transient electric field of the relativistic bunch induces a polarization anisotropy in a nonlinear crystal which is sampled by femtosecond laser pulses. In this paper, the EOS process is studied in detailed numerical calculations. The THz and the laser pulses are treated as wave packets which are propagated through the zinc telluride resp. gallium phosphide crystals. The effects of signal broadening and distortion are taken into account. The time resolution is limited by the lowest lattice oscillation frequency which amounts to 5.3 THz in ZnTe and 11 THz in GaP. The shortest bunch length which can be resolved with moderate distortion is about 200 fs (FWHM) in ZnTe and 100 fs in GaP.  
 
RPAT050 Electro Optic Bunch Length Measurements at the VUV-FEL at DESY laser, linac, polarization, free-electron-laser 3111
 
  • B. Steffen, S. Casalbuoni, E.-A. Knabbe, H. Schlarb, B. Schmidt
    DESY, Hamburg
  • P. Schmüser, A. Winter
    Uni HH, Hamburg
  For the operation of a SASE FEL, the longitudinal bunch length is one of the most critical parameters. At the superconducting linac of the VUV-FEL at DESY, we have installed an electro optic sampling (EOS) experiment to probe the time structure of the electric field of the bunches to better than 100 fs rms. The field-induced birefringence of a ZnTe crystal is detected by a femtosecond laser pulse (TiSa) and the time structure is measured by scanning the relative timing of the electron bunch and the TiSa pulse. A synchronization stability of better than 50 fs between laser and accelerator RF has been achieved. First results on the synchronization measurements and for the bunch length as function of the linac parameters are presented.  
 
RPAT052 Vertical Beam Size Measurement by Streak Camera under Colliding and Single Beam Conditions in KEKB luminosity, beam-beam-effects, positron, feedback 3194
 
  • H. Ikeda, J.W. Flanagan, H. Fukuma, Y. Funakoshi, S. Hiramatsu, T. Mitsuhashi, K. Ohmi, S. Uehara
    KEK, Ibaraki
  Beam behavior of KEKB was studied by measurement of the beam size using a streak camera. Effect of the electron-cloud and the parasitic collision on the vertical beam size was examined in beam collision. We intentionally injected a test bunch of positrons after 2 rf buckets of a bunch to enhance the electron cloud effect and changed electron beam conditions to see the beam-beam effect. The beam size was also measured with a single positron beam and compared with that during collision. The result of the measurement is reported in this paper.  
 
RPAT054 Beam Position Monitor at the PLS BTL linac, monitoring, pick-up, injection 3289
 
  • S.-C. Kim, M.-H. Chun, Y.J. Han, J.Y. Huang, D.T. Kim, W.W. Lee
    PAL, Pohang, Kyungbuk
  Funding: Work supported by the Ministry of Science and Technology, Korea.

Electron Linac at the Pohnag Accelerator Laboratory (PAL) has been operated continuously as the full energy injector for storage ring. Linac and storage ring energy has been 2.0 GeV since Dec. 1994, and 2.5 GeV since Oct. 2002. In Aug. 2004, thirteen BPMs are newly installed at BTL(Beam Transport Line) for beam trajectory measurement and feedback. These BPMs consist of 100mm strip-line electrodes in 150mm long chamber, and 500MHz log-ratio signal processing circuits. BPM data acquisition system is developed as EPICS IOC using NI S-series data acquisition board and NI LabView 7.1. BTL BPMs will be used for optic correction and beam energy feedback for PLS beam injection. This paper describes on design, test results, installation and data acquisition system of the PLS BTL BPM.

 
 
RPAT061 New Electron Beam Position Monitoring and Feedback System Upgrades for the Synchrotron Radiation Source at Daresbury Laboratory monitoring, feedback, storage-ring, pick-up 3538
 
  • R.J. Smith, M. Dufau, B.G. Martlew
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • G. Cox
    CCLRC/DL, Daresbury, Warrington, Cheshire
  Funding: ASTeC Department, CCLRC Daresbury Laboratory.

The installation of a new APPLE/II undulator with user controlled polarisation has necessitated the upgrade of the Electron Beam Position Monitoring (EBPM) detector electronics and position feedback systems. The upgraded installation will utilise commercially available multiplexed detection electronics, coupled with a two phase control system interface replacement. Phase one involves the replacement of the existing G-64 based read-back system with direct analogue connections to the VME beam steering and Feedback system. This allows existing monitoring and feedback software to work with improved update rates (~ 1Hz -> ~ 8Hz). Phase two will see the installation of new high-performance control system front ends and will allow real-time monitoring at up to 100Hz and provide snapshots with resolution of 1-10 KHz.

 
 
RPAT063 A Bunch-By-Bunch and Turn-By-Turn Instrumentation Hardware Upgrade for CESR-c luminosity, positron, synchrotron, instrumentation 3597
 
  • M.A. Palmer, J. Dobbins, C.R. Strohman, E. Tanke
    CESR-LEPP, Ithaca, New York
  Funding: Work supported by the National Science Foundation.

A key factor in the colliding beam performance of the Cornell Electron Storage Ring (CESR) is the impact of parasitic beam-beam interactions between bunches in the two beams as they follow their electrostatically separated orbits in a single vacuum chamber. In order to better investigate the differential performance of bunches in CESR, instrumentation electronics has been developed to allow acquisition of turn-by-turn data from multiple bunches simultaneously. The electronics consists of a standardized digital board centered around an Analog Devices TigerSHARC family digital signal processor, a communications interface, and an interface to the CESR Precision Timing System. Mated to these components is an analog front end and digitizer board which is customized for the particular diagnostic device of interest. Front ends have been developed for beam position monitor, luminosity monitor, and beam profile monitor applications. We describe the design and characterization of this new hardware.

 
 
RPAT064 Beam-Based Calibration of the Electron Energy in the Fermilab Electron Cooler antiproton, dipole, vacuum, kicker 3638
 
  • S. Seletsky
    Rochester University, Rochester, New York
  • A.V. Shemyakin
    Fermilab, Batavia, Illinois
  Electron cooling of 8.9 GeV antiprotons in the Fermilab’s Recycler ring requires precise matching of electron and antiproton velocities. While the final match can be done by optimization of the cooling process, for the very first cooling one should rely on the knowledge of absolute values of electron and antiproton energies. The upper limit for the energy uncertainty of both beams is determined by the Recycler’s momentum aperture and is equal to 0.3%. The paper discusses a method of the electron energy calibration that is based on the measurement of the electron’s Larmor wavelength in the field of the cooling section solenoid. The method was tested in an 18 m long cooling section prototype with 3.5 MeV electrons. An accuracy of 0.3% was demonstrated.  
 
RPAT065 A Wire Scanner Design for Electron Beam Profile Measurement in the Linac Coherent Light Source Undulator undulator, vacuum, linac, impedance 3667
 
  • J.L. Bailey, T.W. Buffington, B.X. Yang
    ANL, Argonne, Illinois
  Funding: Work supported by U. S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38.

The Linac Coherent Light Source (LCLS), currently under design, requires beam diagnostic instruments between the magnets in the beam undulator section. Ten wire scanners are planned as one of the primary instruments to characterize electron beam properties. The development of these wire scanners presents several design challenges due to the need for high accuracy and resolution of the wire motion (3 microns tolerance, typical) and the high intensity of the beam (3400 A over an area of 30 micron rms radius). In this paper, we present the technical specification and design criteria for the scanners. We will also present the mechanical design of the UHV-compatible drive and its engineering analysis. Lastly, we present the wire card design and discuss associated thermal and mechanical issues originating from the highly intense x-ray and electron beams.

 
 
RPAT067 Beam Angle Measurement Using Cherenkov Radiation radiation, optics, scattering, photon 3742
 
  • T. Watanabe, M. Babzien, K. Kusche, V. Yakimenko
    BNL, Upton, Long Island, New York
  A simple beam angle monitor utilizing observation of far-field Cherenkov radiation is being developed. The monitor is independent of beam energy as well as position and requires only modest camera sensitivity. Since the wavefront of Cherenkov radiation is not spherical but planar, the far-field image is supposed to be infinetesimally small in one-dimensional geometrical optics, which may result in high angular resolution. In a practical experiment, however, beam scattering in a radiator and diffraction from a finite size radiation source determine the resolution. Numerical analysis shows that the angular resolution with a 100-um thickness fused silica radiator is 0.8 mrad. The experimental results with 2-mm and 100-um thickness fused silica are shown. The possibility of non-destructive measurement is also discussed.  
 
RPAT068 Proposed Diagnostics for the NSLS-II injection, radiation, synchrotron, diagnostics 3760
 
  • I.P. Pinayev, S.L. Kramer, J. Rose, T.V. Shaftan
    BNL, Upton, Long Island, New York
  Funding: The U.S. Department of Energy under contract No. DE-AC02-98CH10886.

The National Synchrotron Light Source is performing R&D of a new 3 GeV electron storage ring to be used for the facility upgrade. To satisfy the demands for the brightness and stability of the future light source a state-of-the-art diagnostics system is a necessity. We present our preliminary design with focus on the requirements for instrumentation and technical solutions to achieve them.

 
 
RPAT069 Electron Beam Size Measurements in a Cooling Solenoid antiproton, optics, radiation, focusing 3801
 
  • T.K. Kroc, T.B. Bolshakov, A.V. Burov, A.V. Shemyakin
    Fermilab, Batavia, Illinois
  • S. Seletsky
    Rochester University, Rochester, New York
  Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide effective cooling of the antiprotons in the Recycler. A measurement system was developed using movable appertures and steering bumps to measure the beam size in a 20 m long, nearly continuous, solenoid. This paper discusses the required beam parameters, the implimentation of the measurement system and results for our application.

 
 
RPAT070 Mechanical and Thermal Design of the CEBAF Hall A Beam Calorimeter radiation, vacuum, simulation, target 3819
 
  • M.E. Bevins, A.R. Day, P. Degtiarenko, L.A. Dillon-Townes, A. Freyberger, R. Gilman, A. Saha, S. Slachtouski
    Jefferson Lab, Newport News, Virginia
  Funding: DOE.

A calorimeter has been proposed to provide 0.5% - 1.0% absolute measurements of beam current in the Hall A end station of the Thomas Jefferson National Accelerator Facility (JLab) CEBAF machine. Silver and copper calorimeters built in the 1960’s achieved precisions of about 1%. Modern powder metallurgy processes have produced high density, high thermal conductivity tungsten-copper composite materials that will minimize beam loss while maintaining a rapid thermal response time. Heat leaks will be minimized by mounting the mass in vacuum on glass ceramic mounts. A conduction cooling scheme utilizes an advanced carbon fiber compliant thermal interface material. Transient finite difference and finite element models were developed to estimate heat leaks and thermal response times.

 
 
RPAT072 The General ElectroN Induced Emission (GENIE) System dipole, simulation, beam-transport, emittance 3877
 
  • M.A. Epps, R. Kazimi
    Jefferson Lab, Newport News, Virginia
  • P.L. Gueye
    Hampton University, Hampton, Virginia
  A real time beam diagnostic system is proposed for the Jefferson Lab injector region. The General ElectroN Induced Emission System (GENIE) is a package that includes both hardware (beam monitoring devices) and software (for 3D or 4D visualization of the beam transport). This beam diagnostic tool relies primarily on the use of (very small) scintillating fibers placed in different planes to extract the beam profile, beam position, beam current and beam emittance in real time. Accuracies in position and angle could be at the sub- μm and μrad levels, respectively. The beam current could be reconstructed within a few percent. A combined Geant4/Parmela simulation will be developed for beam optic studies. While Parmela offers the power of beam transport with phase matching capabilities (among others), Geant4 provides the power for tracking secondary particles, as well as 3D & 4D visualization. A phase I investigation of GENIE using a 100 keV beam line is discussed in this document.  
 
RPAT078 Bunch Length Measurements Using Coherent Radiation radiation, plasma, vacuum, acceleration 4027
 
  • R. Ischebeck, C.D. Barnes, I. Blumenfeld, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, D.K. Johnson, W. Lu, K.A. Marsh
    UCLA, Los Angeles, California
  • S. Deng, E. Oz
    USC, Los Angeles, California
  • N.A. Kirby
    Stanford University, Stanford, Califormia
  Funding: Work supported by Department of Energy contracts DE-AC02-76SF00515 (SLAC), DE-FG03-92ER40745, DE-FG03-98DP00211, DE-FG03-92ER40727, DE-AC-0376SF0098, and National Science Foundation grants No. ECS-9632735, DMS-9722121 and PHY-0078715.

The accelerating field that can be obtained in a beam-driven plasma wakefield accelerator depends on the current of the electron beam that excites the wake. In the E-167 experiment, a peak current above 10kA will be delivered at a particle energy of 28GeV. The bunch has a length of a few ten micrometers and several methods are used to measure its longitudinal profile. Among these, autocorrelation of coherent transition radiation (CTR) is employed. The beam passes a thin metallic foil, where it emits transition radiation. For wavelengths greater than the bunch length, this transition radiation is emitted coherently. This amplifies the long-wavelength part of the spectrum. A scanning Michelson interferometer is used to autocorrelate the CTR. However, this method requires the contribution of many bunches to build an autocorrelation trace. The measurement is influenced by the transmission characteristics of the vacuum window and beam splitter. We present here an analysis of materials, as well as possible layouts for a single shot CTR autocorrelator.

 
 
RPAT079 Resolution of Transverse Electron Beam Measurements Using Optical Transition Radiation radiation, plasma, acceleration, target 4042
 
  • R. Ischebeck, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, W. Lu
    UCLA, Los Angeles, California
  • S. Deng, E. Oz
    USC, Los Angeles, California
  • M. Lincoln
    Stanford University, Stanford, Califormia
  Funding: Work supported by Department of Energy contracts DE-AC02-76SF00515 (SLAC), DE-FG03-92ER40745, DE-FG03-98DP00211, DE-FG03-92ER40727, DE-AC-0376SF0098, and National Science Foundation grants No. ECS-9632735, DMS-9722121 and PHY-0078715.

In the plasma wakefield acceleration experiment E-167, optical transition radiation is used to measure the transverse profile of the electron bunches before and after the plasma acceleration. The distribution of the electric field from a single electron does not give a point-like distribution on the detector, but has a certain extension. Additionally, the resolution of the imaging system is affected by aberrations. The transverse profile of the bunch is thus convolved with a point spread function (PSF). Algorithms that deconvolve the image can help to improve the resolution. Imaged test patterns are used to determine the modulation transfer function of the lens. From this, the PSF can be reconstructed. The Lucy-Richardson algorithm is used to deconvolute this PSF from test images.

 
 
RPAT082 Coherent Transition Radiation To Measure the SLAC Electron Bunch Length radiation, background, alignment, laser 4102
 
  • P. Muggli
    USC, Los Angeles, California
  • C.D. Barnes, M.J. Hogan, P. Krejcik, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • R. Ischebeck, H. Schlarb
    DESY, Hamburg
  Funding: Work supported by U.S. DOE.

Ultrashort electron bunches are now available at Stanford Linear Accelerator Center and are use mainly to produce short bursts of x-rays in a magnetic undulator and for plasma wakefield acceleration experiments. The shortest bunches have an rms longitudinal width of 10 microns, and a peak current of about 30 kA. Methods to measure such short bunch lengths include electro-optic modulation of a short laser pulse in a nonlinear crystal and coherent transition (CTR) autocorrelation. The transition radiation spectrum emitted by the bunches when traversing a 1 micron thin titanium foil is coherent for wavelengths longer that the bunch length and extends into the millimeter wavelength range. A CTR far-infrared autocorrelator was used to measure the bunch length as a function of the accelerator. The results obtained with this autocorrelator are the only measurements of the SLAC ultra-short bunches to date. Experimental results, as well as the limitations of the measurements and the future improvements to the autocorrelator will be presented.

 
 
RPAT083 Beam Profile Measurements and Simulations of the PETRA Laser-Wire laser, photon, simulation, collider 4123
 
  • J. Carter, I.V. Agapov, G.A. Blair, G.E. Boorman, C.D. Driouichi, F. Poirier, M.T. Price
    Royal Holloway, University of London, Surrey
  • K. Balewski, H.-C. Lewin, S. Schreiber, K. Wittenburg
    DESY, Hamburg
  • S.T. Boogert, S. Malton
    UCL, London
  • N. Delerue, D.F. Howell
    OXFORDphysics, Oxford, Oxon
  • T.  Kamps
    BESSY GmbH, Berlin
  The laser-wire will be an essential diagnostic tool at the International Linear Collider and advanced light sources. It uses a finely focussed laser beam to measure the transverse profile of electron bunches by detecting the Compton-scattered photons (or electrons) downstream of where the laser beam intersects the electron beam. Such a system has been installed at the PETRA storage ring at DESY, which uses a piezo-driven mirror to scan the laser light across the electron beam. Latest experimental results are presented and compared to detailed simulations using Geant4.  
 
RPAT085 Initial Imaging of 7-GeV Electron Beams with OTR/ODR Techniques at APS radiation, dipole, booster, beam-losses 4162
 
  • A.H. Lumpkin, W. Berg, N. Sereno, C. Yao
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The development of nonintercepting (NI) diagnostics continues to be of interest at the Advanced Photon Source (APS) as well as elsewhere. In the three rings of the APS facility we use optical synchrotron radiation generated as the electron beam transits the dipole magnetic fields as an NI mechanism to image the beam during top-up operations. However, in the straight transport lines an alternative method is needed. Optical diffraction radiation (ODR) is under investigation to monitor 7-GeV beam trajectory and potentially transverse shape in the booster-to-storage ring (BTS) beamline during top-up operations. We have performed our initial measurements with an Al blade/mirror that served as an optical transition radiation (OTR) monitor when fully inserted into the beam and as an ODR monitor when the beam passed near the edge. In the case of ODR, appreciable signal is emitted by the metal when gamma times the reduced ODR wavelength is comparable to the impact parameter, where gamma is the Lorentz factor. Visible light optics and a standard CCD camera could thus be used for a few-mm impact parameter. We attribute the near-field signal for 1.5- to 3.0-mm impact parameters predominately to the ODR mechanism.

 
 
RPAT086 Dual-Sweep Streak Camera Measurements of the APS User Beams storage-ring, emittance, single-bunch, diagnostics 4185
 
  • A.H. Lumpkin, B.X. Yang
    ANL, Argonne, Illinois
  • F. Sakamoto
    UTNL, Ibaraki
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract Number W-31-109-ENG-38.

The Advanced Photon Source (APS) is a hard x-ray user facility based on a 7-GeV storage ring (SR). To accommodate the requests of the diverse user community, the APS normally runs with a 24-singlets fill pattern, a hybrid fill with a singlet and eight septuplets, or a 324-singlet fill pattern. In all cases the total stored beam current is 100 mA, with the lattice providing a natural emittance of about 2.5 nm rad. The first two patterns are used with a top-up mode that involves injection of one pulse of ~2.5 nC every two minutes into the designated SR bucket. Since the partition of bunch current varies for the different fills as well as the loading of the rf cavities, dual-sweep streak camera measurements (Hamamatsu model C5680) have been performed to characterize the average and individual bunch lengths in the fill patterns and the phase slew that occurs within the patterns. The bunch lengths vary from 32 ps (σ) within the septuplet to 50 ps (σ) for the singlet in the hybrid fill. The phase slew is significant in the hybrid fill across the eight septuplets. Example streak images of each pattern will be presented and discussed.

 
 
RPAT087 Design of a High-Resolution Optical Transition Radiation Imager System for the Linac Coherent Light Source Undulator undulator, optics, radiation, linac 4209
 
  • B.X. Yang, J.L. Bailey, S.J. Stein, D.R. Walters
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38.

The Linac Coherent Light Source (LCLS), a free-electron x-ray laser, is under design and construction. Its high intensity electron beam, 3400 A in peak current and 46 TW in peak power, is concentrated in a small area (30 micrometer rms in both horizontal and vertical directions) inside its undulator. Ten optical transition radiation (OTR) imagers are planned between the undulator segments for the characterization of the transverse profiles of the electron beam. In this paper, we present the performance requirements and technical requirements of the OTR imagers. We will discuss in detail the design of the OTR screen, the arrangement and modeling of the imaging optics, and the mechanical design and analysis of the compact camera module. Through a unique optical arrangement, this imager will achieve a fine resolution (12 micrometer rms or better) over the entire field of view (5 mm × 5 mm). The compact camera module will fit in the limited space available with remote focus adjustment. A digital camera will be used to read out the beam images in a programmable region (5 mm × 0.5 mm) at the full beam repetition rate (120 Hz), or over the entire field at a lower rate (15 Hz).

 
 
RPAT088 Energy-Spread-Feedback System for the KEKB Injector Linac feedback, linac, target, positron 4212
 
  • M. Satoh, K.  Furukawa, T. Suwada
    KEK, Ibaraki
  New energy-spread feedback system using nondestructive energy-spread monitors have been developed in order to control and stabilize the energy spreads of single-bunch electron and positron beams in the KEKB injector linac. The well-controlled feedback systems of the injector linac are successfully working in dairy operation not only for keeping the injection rate higher along with the beam-orbit and energy feedback systems but also for reducing a background level to the high-energy B-factory experiment. The energy spreads of the injection beams are well stabilized within 0.2%, 0.5% and 0.3% for the electron beam, the positron beam, and the high-current primary electron beam for positron production, respectively, through the energy-spread feedback system under the nominal operation condition. In this paper, we will report in detail the energy-spread feedback system using the nondestructive energy-spread monitors with multi-strip-line electrodes and their performance in the KEKB operation.  
 
RPAT089 Advances in Optical Transition and Diffraction Radiation Emittance Diagnostics emittance, simulation, optics, diagnostics 4224
 
  • R.B. Fiorito, A.G. Shkvarunets
    IREAP, College Park, Maryland
  • T. Watanabe, V. Yakimenko
    BNL, Upton, Long Island, New York
  Funding: Office of Naval Research and the DOD Joint Technology Office.

We have performed a series of experiments using Optical Transition Radiation and Optical Diffraction Radiation Interferometry to measure the two orthogonal (x,y) rms divergences of the Brookhaven National Laboratory’s Advanced Test Facility electron beam operating at an energy of 50 MeV. Measurement of the rms divergences at the (x,y) beam waist conditions, together with corresponding measurements of the rms beam sizes allows a determination of the rms x and y emittances. A comparison of the results using OTRI and ODTRI are presented.

 
 
RPAT091 Longitudinal Electron Bunch Diagnostics Using Coherent Transition Radiation radiation, simulation, laser, linac 4254
 
  • D. Mihalcea, C.L. Bohn
    Northern Illinois University, DeKalb, Illinois
  • U. Happek
    UGA, Athens, Georgia
  • P. Piot
    Fermilab, Batavia, Illinois
  The longitudinal charge distribution of electron bunches in the Fermilab A0 photo-injector was determined by using the coherent transition radiation produced by electrons passing through a thin metallic foil. The auto-correlation of the transition radiation signal was measured with a Michelson type interferometer. The response function of the interferometer was determined from measured and simulated power spectra for low electron bunch charge and maximum longitudinal compression. Kramers-Kroning technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms).  
 
RPAT092 Conceptual Design of an Insertion Device for Non-Destructive Beam Diagnostics of a Low-Emittance Synchrotron Light Source undulator, photon, radiation, diagnostics 4275
 
  • M. Masaki
    JASRI/SPring-8, Hyogo
  An insertion device is proposed to measure small vertical angular divergence and energy spread (dE/E) of electron beam in a low-emittance synchrotron light source. In accelerators such as the SPring-8 storage ring operated on the small emittance-coupling ratio, vertical divergence of spectral photon flux produced by electron beam in a conventional undulator of several meters long will be dominated by natural divergence of the undulator radiation. Therefore, the divergence of spectral flux is not useful for vertical emittance diagnostics. The proposed insertion device consists of N short undulator sections as x-ray radiators cascaded through vertical deflective sections to make a half-period cosine-like electron trajectory. Two radiation parts of the upper and lower sides are formed due to up-and-down electron orbit by the deflective sections. X-rays emitted from the two radiation parts interfere at observation point far from the insertion device. It was numerically studied that the vertical angular divergence in the sub-micro radian range and the energy spread of the 1·10-3 order could be measured by visibility and envelope width of an observed interference pattern, respectively.  
 
RPAT093 Libera Electron Beam Position Processor feedback, instrumentation, booster, injection 4284
 
  • R. Ursic, A. Kosicek
    Instrumentation Technologies, Solkan
  Libera is a product family delivering unprecedented possibilities for either building powerful single station solutions or architecting complex feedback systems in the field of accelerator instrumentation and controls. This paper presents functionality and field performance of its first member, the electron beam position processor. It offers superior performance with multiple measurement channels delivering simultaneously position measurements in digital format with MHz kHz and Hz bandwidths. This all-in-one product, facilitating pulsed and CW measurements, is much more than simply a high performance beam position measuring device delivering micrometer level reproducibility with sub-micrometer resolution. Rich connectivity options and innate processing power make it a powerful feedback building block. By interconnecting multiple Libera electron beam position processors one can build a low-latency high throughput orbit feedback system without adding additional hardware. Libera electron beam position processor is ideally suited for the Third and the Fourth generation light sources.  
 
RPAT095 Time Resolved X-Ray Spot Size Diagnostic diagnostics, target, alignment, shielding 4302
 
  • R.A. Richardson, F.W. Chambers, S. Falabella, G. Guethlein, B.A. Raymond, J.T. Weir
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

A diagnostic was developed for the determination of temporal history of an X-ray spot. A pair of thin (0.5 mm) slits image the x-ray spot to a fast scintillator which is coupled to a fast detector, thus sampling a slice of the X-Ray spot. Two other scintillator/detectors are used to determine the position of the spot and total forward dose. The slit signal is normalized to the dose and the resulting signal is analyzed to get the spot size. The position information is used to compensate for small changes due to spot motion and misalignment. The time resolution of the diagnostic is about 1 ns and measures spots from 0.5 mm to over 3 mm. The theory and equations used to calculate spot size and position are presented, as well as data. The calculations assume a symmetric, Gaussian spot. The spot data is generated by the ETA II accelerator, a 2kA, 5.5 MeV, 60ns electron beam focused on a Tantalum target. The spot generated is typically about 1 mm FWHM. Comparisons are made to an X-ray pinhole camera which images the XRay spot (in 2D) at four time slices.

 
 
RPAT097 2-D Low Energy Electron Beam Profile Measurement Based on Computer Tomography Algorithm with Multi-Wire Scanner emittance, gun 4323
 
  • N.J. Yu, K.Y. Gong, Q. F. Li, C.-X. Tang, S. Zheng
    TUB, Beijing
  A new method for low energy electron beam profile measurement is advanced, which presents a full 2-D beam profile distribution other than the traditional 2-D beam profile distribution given by 1-D vertical and horizontal beam profiles. The method is based on the CT (Computer Tomography) algorithm. Multi-sets of data about the 1-D beam profile projections are attained by rotating the multi-wire scanner. Then a 2-D beam profile is reconstructed from these projections with CT algorithm. The principle of this method is presented. The simulation and the experiment results are compared and analyzed in detail.  
 
RPAT100 Radiation-Hard Beam Position Detector for Use in the Accelerator Dump Lines target, radiation, monitoring, radio-frequency 4341
 
  • P. Degtiarenko, D.W. Dotson, V.P. Popov
    Jefferson Lab, Newport News, Virginia
  Funding: This work supported by the U.S. Department of Energy under contract DE-AC05-84ER40150

The new proposed method of beam position measurement is particularly suitable for monitoring high energy, and high power accelerated beams of charged particles in the vicinity of power beam dumps. Generally, the beam quality in those areas is very poor, and any equipment positioned there must be extremely resistant to radiation damage. We have found that a plate made of Chemical Vapor Deposition (CVD) Silicon Carbide (SiC) has a set of physical properties that make it suitable for such an application. CVD SiC material is a chemically inert, extremely radiation-hard, thermo-resistive semiconductor capable of withstanding working temperatures up to 2000 degrees Kelvin. It has good thermal conductivity comparable to that of Aluminum, which makes it possible to use it in high-current particle beams. High electrical resistivity of the material, and its semiconductor properties allow characterization of the position of a particle beam crossing such a plate by measuring balance of electrical currents at the plate ends. The design of a test device, and first results are presented in the report.

 
 
ROAB001 DARHT-II Long-Pulse Beam-Dynamics Experiments induction, vacuum, ion, background 19
 
  • C. Ekdahl, E.O. Abeyta, R. Bartsch, L. Caudill, K.-C.D. Chan, D. Dalmas, S. Eversole, R.J. Gallegos, J. Harrison, M. Holzscheiter, E. Jacquez, J. Johnson, B.T. McCuistian, N. Montoya, S. Nath, K. Nielsen, D. Oro, L. Rodriguez, P. Rodriguez, L.J. Rowton, M. Sanchez, R. Scarpetti, M. Schauer, D. Simmons, H.V. Smith, J. Studebaker, G. Sullivan, C. Swinney, R. Temple
    LANL, Los Alamos, New Mexico
  • H. Bender, W. Broste, C. Carlson, G. Durtschi, D. Frayer, D. Johnson, K. Jones, A. Meidinger, K.J. Moy, R. Sturgess, A. Tipton, C.-Y. Tom
    Bechtel Nevada, Los Alamos, New Mexico
  • R.J. Briggs
    SAIC, Alamo, California
  • Y.-J. Chen, T.L. Houck
    LLNL, Livermore, California
  • S. Eylon, W.M. Fawley, E. Henestroza, S. Yu
    LBNL, Berkeley, California
  • T.P. Hughes, C. Mostrom, Y. Tang
    ATK-MR, Albuquerque, New Mexico
  • M.E. Schulze
    GA, San Diego, California
  Funding: This work was supported by the U.S. National Nuclear Security Agency and the U.S. Department of Energy under contract W-7405-ENG-36.

When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2-kA, 18-MeV electron beam with more than 1500-ns current/energy "flat-top." In initial tests DARHT-II has already accelerated beams with current pulse lengths from 500-ns to 1200-ns full-width at half maximum (FWHM) with more than1.2-kA, 12.5-MeV peak current and energy. Experiments are now underway with a ~2000-ns pulse length, but reduced current and energy. These pulse lengths are all significantly longer than any other multi-MeV LIA, and they define a novel regime for high-current beam dynamics, especially with regard to beam stability. Although the initial tests demonstrated absence of BBU, the pulse lengths were too short to test the predicted protection against ion-hose instability. The present experiments are designed to resolve these and other beam-dynamics issues with a ~2000-ns pulse length beam.

 
 
ROAB006 Pulsed Power Drivers and Diodes for X-Ray Radiography pulsed-power, impedance, vacuum, plasma 510
 
  • K.J. Thomas
    AWE, Reading
  Flash radiography has been used as a diagnostic for explosively driven hydrodynamics experiments for several decades following the pioneering work of J C Martin and his group at AWE. Relatively simple pulsed power drivers operating between 1 and 10 MV coupled to experimentally optimised electron beam diodes have achieved great success in a number of different classes of these experiments. The next generation of radiographic facilities will aim to improve even further the radiographic performance achievable by developing both the electron beam diodes used and the accelerators that drive them. The application of the rod-pinch diode to an Inductive Voltage Adder at 2 MV in the US has already advanced the quality of radiography available for relatively thin objects. For the thickest objects accelerators operating at up to 15 MV and diodes capable of focusing electron beams to intensities of ~ 1 MA/cm2 for tens of nanoseconds will be required in the future. Since the various candidate diode configurations operate in both high and low impedance regimes there is a further challenge to design and engineer an accelerator capable of driving whichever one, or more, are eventually used.  
 
ROPB001 Suppressing Electron Cloud in Future Linear Colliders simulation, damping, vacuum, collider 24
 
  • M.T.F. Pivi, R.E. Kirby, T.O. Raubenheimer
    SLAC, Menlo Park, California
  • F. Le Pimpec
    PSI, Villigen
  Funding: Work supported by the U.S. DOE under contract DE-AC02- 76SF00515.

Any accelerator circulating positively charged beams can suffer from a build-up of an electron cloud in the beam pipe. The cloud develops through ionization of residual gases, synchrotron radiation and secondary electron emission and, when severe, can cause instability, emittance blow-up or loss of the circulating beam. The electron cloud is potentially a limiting effect for both the Large Hadron Collider (LHC) and the International Linear Collider (ILC). For the ILC positron damping ring, the development of the electron cloud must be suppressed. This paper presents the various effects of the electron cloud and evaluates their significance. It also discusses the state-of-the-art of the ongoing international R&D program to study potential remedies to reduce the secondary electron yield to acceptably low levels.

 
 
ROPB002 Experiments Studying Desorbed Gas and Electron Clouds in Ion Accelerators ion, quadrupole, diagnostics, simulation 194
 
  • A.W. Molvik, J.J. Barnard, R.H. Cohen, A. Friedman, M. Kireeff Covo, S.M. Lund
    LLNL, Livermore, California
  • D. Baca, F.M. Bieniosek, C.M. Celata, P.A. Seidl, J.-L. Vay, W. Waldron
    LBNL, Berkeley, California
  • J.L. Vujic
    UCB, Berkeley, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL under contract No. W-7405-Eng-48, and by LBNL under Contract DE-AC03-76F00098.

Electron clouds and gas pressure rise limit the performance of many major accelerator rings. We are studying these issues experimentally with ~1 MeV heavy-ion beams, coordinated with significant efforts in self-consistent simulation and theory.* The experiments use multiple diagnostics, within and between quadrupole magnets, to measure the sources and accumulation of electrons and gas. In support of these studies, we have measured gas desorption and electron emission coefficients for potassium ions impinging on stainless steel targets at angles near grazing incidence.** Our goal is to measure the electron particle balance for each source – ionization of gas, emission from beam tubes, and emission from an end wall – determine the electron effects on the ion beam and apply the increased understanding to mitigation.

*J-L. Vay, Invited paper, session TICP; R. H. Cohen et al., PRST-AB 7, 124201 (2004). **M. Kireeff Covo, this conference; A. W. Molvik et al., PRST-AB 7, 093202 (2004).

 
 
ROPB003 Electron Cloud Dynamics in High-Intensity Rings SNS, dipole, quadrupole, space-charge 245
 
  • L. Wang, J. Wei
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy. SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

Electron cloud due to beam induced multipacting is one of the main concerns for the high intensity rings because the electron multipacting becomes stronger with the increment of beam intensity. Electrons generated and accumulated inside the beam pipe form an "electron cloud" that interacts with the circulating charged particle beam. With sizeable amount of electrons, this interaction can cause beam instability, beam loss and emittance growth. At the same time, the vacuum pressure will rise due to electron desorption. This talk intends to provide an overview of the dynamics of the typical electron multipacting in various magnetic fields and mitigation measures in both long bunch and short bunch rings.

 
 
ROPB004 Effect of Lattice and Electron Distribution in Electron-Cloud Instability Simulations for the CERN SPS and LHC emittance, lattice, dipole, simulation 387
 
  • E. Benedetto, E. Benedetto
    Politecnico di Torino, Torino
  • G. Arduini, F. Roncarolo, F. Zimmermann
    CERN, Geneva
  • B. Feng, A.F. Ghalam, T.C. Katsouleas
    USC, Los Angeles, California
  • G. Franchetti
    GSI, Darmstadt
  • K. Ohmi
    KEK, Ibaraki
  • G. Rumolo
    CELLS, Bellaterra (Cerdanyola del Vallès)
  Several simulation codes have been adapted so as to model the single-bunch electron-cloud instability including a realistic variation of the optical functions with longitudinal position. In addition, the electron cloud is typically not uniformly distributed around the ring, as frequently assumed, but it is mainly concentrated in certain regions with specific features, e.g., regions which give rise to strong multipacting or suffer from large synchrotron radiation flux. Particularly, electrons in a dipole magnet are forced to follow the vertical field lines and, depending on the bunch intensity, they may populate two vertical stripes, symmetrically located on either side of the beam. In this paper, we present simulation results for the CERN SPS and LHC, which can be compared with measurements or analytical predictions.  
 
ROPB006 Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling ion, simulation, quadrupole, heavy-ion 525
 
  • J.-L. Vay, M.A. Furman, P.A. Seidl
    LBNL, Berkeley, California
  • R.H. Cohen, K. Covo, A. Friedman, D.P. Grote, A.W. Molvik
    LLNL, Livermore, California
  • P. Stoltz, S.A. Veitzer
    Tech-X, Boulder, Colorado
  • J. Verboncoeur
    UCB, Berkeley, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL and LBNL under contracts W-7405-Eng-48, and DE-AC03-76F00098.

Electron clouds and gas pressure rise limit the performance of many major accelerators. A multi-laboratory effort to understand the underlying physics via the combined application of experiment,* theory, and simulation is underway. We present here the status of the simulation capability development, based on a merge of the three-dimensional parallel Particle-In-Cell accelerator code WARP and the electron cloud code POSINST, with additional functionalities.** The development of the new capability follows a "roadmap" describing the different functional modules, and their inter-relationships, that are ultimately needed to reach self-consistency. Newly developed functionalities include a novel particle mover bridging the time scales between electrons and ions motion.*** Samples of applications of the new capability to the modeling of intense charge dominated beams**** and LHC beams***** will be shown as available.

*A.W. Molvik, these proceedings. **J.-L. Vay, Proc. "ECLOUD04," Napa (California), 2004. ***R.H. Cohen, these proceedings. ****P.A. Seidl, these proceedings. *****M.A. Furman, these proceedings.

 
 
ROPB007 3-D Parallel Simulation Model of Continuous Beam-Electron Cloud Interactions simulation, betatron, emittance, synchrotron 549
 
  • A.F. Ghalam, T.C. Katsouleas
    USC, Los Angeles, California
  • E. Benedetto, F. Zimmermann
    CERN, Geneva
  • V.K. Decyk, C. Huang, W.B. Mori
    UCLA, Los Angeles, California
  • G. Rumolo
    GSI, Darmstadt
  A 3D Particle-In-Cell model for continuous modeling of beam and electron cloud interaction in a circular accelerator is presented. A simple model for lattice structure, mainly the Quadruple and dipole magnets and chromaticity have been added to a plasma PIC code, QuickPIC, used extensively to model plasma wakefield acceleration concept. The code utilizes parallel processing techniques with domain decomposition in both longitudinal and transverse domains to overcome the massive computational costs of continuously modeling the beam-cloud interaction. Through parallel modeling, we have been able to simulate long-term beam propagation in the presence of electron cloud in many existing and future circular machines around the world. The exact dipole lattice structure has been added to the code and the simulation results for CERN-SPS and LHC with the new lattice structure have been studied. Also the simulation results are compared to the results from the two macro-particle modeling for strong head-tail instability. It is shown that the simple two macro-particle model can capture some of the physics involved in the beam- electron cloud interaction qualitatively.  
 
ROPB009 Betatron Sidebands Due to Electron Clouds Under Colliding Beam Conditions luminosity, betatron, positron, feedback 680
 
  • J.W. Flanagan, H. Fukuma, Y. Funakoshi, S. Hiramatsu, H. Ikeda, K. Ohmi, M. Tobiyama, S. Uehara, S. Uno
    KEK, Ibaraki
  • E. Perevedentsev
    BINP SB RAS, Novosibirsk
  Recently, we have observed vertical betatron sidebands in the transverse beam spectra of positron bunches at the KEKB LER which are associated with the presence of electron clouds. When the LER is operating in single-beam mode (no colliding bunches in the HER), these sidebands are sharply peaked. When the bunches are in collision for physics running, the sidebands are still present but are found to be smeared out. The bunch-by-bunch specific luminosity is lower for bunches with sidebands than for those without sidebands. In this paper, the behavior of the sidebands in collision and the effects on luminosity are discussed.  
 
ROPB010 Self-Consistent Electron-Cloud Simulation for Long Proton Bunches proton, simulation, lattice, dipole 722
 
  • A.P. Shishlo, S.M. Cousineau, V.V. Danilov, S. Henderson, J.A. Holmes, Y. Sato
    ORNL, Oak Ridge, Tennessee
  • S.-Y. Lee
    IUCF, Bloomington, Indiana
  • R.J. Macek
    LANL, Los Alamos, New Mexico
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The results of numerical electron-cloud simulations for long-bunch proton beams in accumulator rings are presented and compared with data from the Proton Storage Ring at LANL. The frequency spectra and growth rate of proton-bunch transverse instabilities are studied as functions of the RF cavity voltage, external magnetic fields, beam pipe surface properties, and other factors. We used the recently developed electron-cloud module in the ORBIT code. The model includes a fully self-consistent coupled treatment of the "proton bunch – electron-cloud" dynamics and the multipacting process with a realistic secondary emission surface model. Realistic lattices and proton bunch distributions are used. The efficiency of electron-cloud instability suppression has also been studied using a new ORBIT model.

 
 
RPPE001 The CARE Accelerator R&D Programme in Europe proton, acceleration, linac, hadron 749
 
  • O. Napoly, R. Aleksan, A. Devred
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • A. Den Ouden
    Twente University, Laser Physics and Non-Linear Optics Group, Enschede
  • R. Garoby, R. Losito, L. Rinolfi, F. Ruggiero, W. Scandale, D. Schulte, M. Vretenar
    CERN, Geneva
  • T. Garvey, F. Richard
    LAL, Orsay
  • A. Ghigo
    INFN/LNF, Frascati (Roma)
  • E. Gschwendtner
    CUI, Geneva
  • H. Mais, D. Proch
    DESY, Hamburg
  • V. Palladino
    INFN-Napoli, Napoli
  Funding: This work is supported by the European Community-Research Infrastructure Activity under the FP6 “Structuring the European Research Area” programme (CARE, contract number RII3-CT-2003-506395).

CARE, an ambitious and coordinated programme of accelerator research and developments oriented towards HEP projects, has been launched in January 2004 by the main European laboratories and the European Commission within the 6th Framework Programme. This programme aims at improving existing infrastructures dedicated to future projects such as linear colliders, upgrades of hadron colliders and high intensity proton drivers. An important part of this programme is devoted to advancing the performance of the superconducting technology, both in the fields of RF cavities for electron and proton acceleration and of high field magnets, as well as to developing high intensity electron and proton injectors. We describe the R&D plans of the four main R&D activities and report on the results and progress obtained so far.

 
 
RPPE005 Ions for LHC: Beam Physics and Engineering Challenges ion, injection, luminosity, linac 946
 
  • S. Maury, M.-E. Angoletta, V. Baggiolini, A. Beuret, A. Blas, J. Borburgh, H.-H. Braun, C. Carli, M. Chanel, T. Fowler, S.S. Gilardoni, M. Gourber-Pace, S. Hancock, C.E. Hill, M. Hourican, J.M. Jowett, K. Kahle, D. Kuchler, E. Mahner, D. Manglunki, M. Martini, M.M. Paoluzzi, J. Pasternak, F. Pedersen, U. Raich, C. Rossi, J.-P. Royer, K. Schindl, R. Scrivens, L. Sermeus, E.N. Shaposhnikova, G. Tranquille, M. Vretenar, Th. Zickler
    CERN, Geneva
  The first phase of the heavy ion physics program at the LHC aims to provide lead-lead collisions at energies of 5.5 TeV per colliding nucleon pair and ion-ion luminosity of 1027 cm-2s-1. The transformation of CERN’s ion injector complex (Linac3-LEIR-PS-SPS) presents a number of beam physics and engineering challenges. Conversion of the Low Energy Antiproton Ring (LEAR) to a Low Energy Ion Ring (LEIR) is under way: the high-current electron cooling system, novel broad-band RF cavities and vacuum equipment to achieve 10-12 mbar are the major challenges. Commissioning of LEIR with beam will start in the middle of 2005. Major hardware changes in Linac3 include the installation of the new ECR ion source and of the energy ramping cavity. The PS will have a new injection system and RF gymnastics. A stripping insertion between PS and SPS must not disturb the proton operation. In the LHC itself, there are fundamental performance limitations due to various beam loss mechanisms. To study these without risk of damage there will be an initial period of operation with a reduced number of nominal intensity bunches. While reducing the work required to commission the LHC with ions in 2008, this will still enable early physics discoveries.  
 
RPPE009 Extremely High Current, High-Brightness Energy Recovery Linac gun, linac, emittance, simulation 1150
 
  • I. Ben-Zvi, D.S. Barton, D.B. Beavis, M. Blaskiewicz, J.M. Brennan, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, R. Connolly, D.M. Gassner, J.G. Grimes, H. Hahn, A. Hershcovitch, H.-C. Hseuh, P.D.J. Johnson, D. Kayran, J. Kewisch, R.F. Lambiase, V. Litvinenko, G.T. McIntyre, W. Meng, T.C.N. Nehring, T. Nicoletti, B. Oerter, D. Pate, J. Rank, T. Rao, T. Roser, T. Russo, J. Scaduto, Z. Segalov, K. Smith, N.W.W. Williams, K.-C. Wu, V. Yakimenko, K. Yip, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • H. Bluem, A. Burger, M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • J.R. Delayen, L. W. Funk, P. Kneisel, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
  Funding: Under contract with the U.S. Department of Energy, U.S. DOD Office of Naval Research and Joint Technology Office.

Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL’s Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

 
 
RPPE010 Beam Transport Devices for the 10kW Free Electron Laser at Thomas Jefferson National Accelerator Facility laser, vacuum, beam-transport, photon 1210
 
  • L.A. Dillon-Townes, C.P. Behre, M.E. Bevins, G.H. Biallas, D. Douglas, C.W. Gould, J.G. Gubeli, D.H. Kashy, R. Lassiter, L. Munk, G. Neil, M.D. Shinn, S. Slachtouski, D. Waldman
    Jefferson Lab, Newport News, Virginia
  Funding: Department of Energy

The beam transport vacuum components for the 10 kW Free Electron Laser (FEL) at Thomas Jefferson National Accelerator Facility (TJNAF) were designed to address 10 MeV electron beam characteristics and maintain an accelerator transport vacuum of 10-9 torr. The components discussed include a novel zero length beam clipper, novel shielded bellows, one decade differential pumping stations with a 7.62 cm (3.0”) aperture, and a 50 kW beam dump. Incorporation of these accelerator transport components assist in establishing the environment needed for the electron beam to produce the optical light required to lase at 10 kW.

 
 
RPPE015 Diagnostics and Protection Control for IREN Linac Test Facility diagnostics, linac, monitoring, instrumentation
 
  • V.N. Zamriy
    JINR, Dubna, Moscow Region
  The diagnostic and protection control systems for the full-scale test facility of the linear electron accelerator are constructed according to the project on pulsed neutron source IREN. Combined control schemes of timed diagnostics of a duty cycle and real-time protection control are created for the linac test facility. Applicability of the diagnostics systems of cycle parameters and deviations of a status for control of the mode of protection is shown. Multichannel control modules of the protection system have been developed for logging and diagnostics of a status change, the alarms and control of a mode of operation. The applied multiway controllers for duty protection with fast locking of cycles of the IREN linac are presented.  
 
RPPE027 High Intensity High Energy E-Beam Interacting with a Thin Solid State Target: First Results at AIRIX focusing, target, scattering, emittance 1982
 
  • M. Caron, F. Cartier, D.C. Collignon, L.H. Hourdin, E. Merle, M. Mouillet, C. Noel, D.P. Paradis, O.P. Pierret
    CEA, Pontfaverger-Moronvilliers
  • O. Mouton, N. Pichoff
    CEA/DAM, Bruyères-le-Châtel
  Funding: CEA, Polygone d’Expérimentation de Morronvilliers, LEXA F-51 475 Pontfaverger (France).

AIRIX is a 2 kA, 20 MeV, 60 ns linear accelerator dedicated to X-ray flash radiography. During a regular running phase, the primary electron beam is accelerated to and focused on a high atomic number target in order to generate X-rays by brembtrahlung mainly. The huge energy density deposited into the material is such that temperature rises up to 15000°K and that clusters and particles are violently ejected from the surface. In that mechanism, the backward emission speed can reach 5 km.s-1 and the debris can gradually accumulate and subsequently contaminate some sensitive parts of the machine. In order to protect the whole accelerating line from the detrimental effect of back-ejected particles, we have investigated the technical feasibility of a thin foil implementation upstream the X-ray converter.

 
 
RPPE032 Measurement of the Secondary Emission Yield of a Thin Diamond Window in Transmission Mode vacuum, gun, cathode, linac 2251
 
  • X.Y. Chang, I. Ben-Zvi, A. Burrill, S. Hulbert, P.D.J. Johnson, J. Kewisch, T. Rao, Z. Segalov, J. Smedley, Y. Zhao
    BNL, Upton, Long Island, New York
  The secondary emission enhanced photoinjector (SEEP) is a promising new approach to the generation of high-current, high-brightness electron beams. A low current primary electron beam with energy of a few thousand electron-volts strikes a specially prepared diamond window which emits secondary electrons with a current two orders of magnitude higher. The secondary electrons are created at the back side of the diamond and drift through the window under the influence of a strong electrical field. A hydrogen termination at the exit surface of the window creates a negative electron affinity (NEA) which allows the electrons to leave the diamond. An experiment was performed to measure the secondary electron yield and other properties. The results are discussed in this paper.  
 
RPPE036 Pressure Field Distribution in a Conical Tube with Transient and Outgassing Gas Sources vacuum, radiation, storage-ring 2422
 
  • F.T. Degasperi
    FATEC-SP, Sao Paulo, SP
  • M.N. Martins, J. Takahashi
    USP/LAL, Bairro Butantan
  • L.L. Verardi
    IBILCE - UNESP, Sao Jose do Rio Preto, SP
  Funding: Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESP Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPq

This work presents numerical results for the pressure field distribution along the axis of conical tube with outgassing plus a transient degassing. Several areas of applied physics deal with problems in high-vacuum and ultra high-vacuum technology that present tubular form. In many cases one finds conical tubes, which are frequently present in particle accelerators, colliders, storage rings and several electron devices. This work presents and describes in detail the pressure field in a conical tube with a transient gas source, for instance, when particles from the beam hit the walls, plus the steady state outgassing. Mathematical and physical formulations are detailed, and the boundary conditions are discussed. These concepts and approach are applied to usual realistic cases, with typical laboratory dimensions.

 
 
RPPE039 Alumina Ceramics Vacuum Duct for the 3GeV-RCS of the J-PARC impedance, vacuum, dipole, quadrupole 2604
 
  • M. Kinsho
    Japan Atomic Energy Institute, Linac Laboratory, Tokai-Mura
  • Z. Kabeya
    MHI, Nagoya
  • N. Ogiwara
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • Y. Saito
    KEK, Ibaraki
  It was success to develop alumina ceramics vacuum ducts for the 3GeV-RCS of J-PARC at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5m-long duct with a circular cross section for use in the quadrupole magnet, the other being 3.5m-long and bending 15 degrees, with a race-track cross section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.5-0.8 m in length by brazing. The alumina ceramics ducts have copper stripes on the outside surface of the ducts to reduce the duct impedance. One of the ends of each stripe is connected to a titanium flange by way of a capacitor so to interrupt an eddy current circuit. The copper stripes are produced by an electroforming method in which a stripe pattern formed by Mo-Mn metallization is first sintered on the exterior surface and then overlaid by PR-electroformed copper (Periodic current Reversal electroforming method). In order to reduce emission of secondary electrons when protons or electrons strike the surface, TiN film is coated on the inside surface of the ducts.  
 
RPPE047 Upgrade of RHIC Vacuum Systems for High Luminosity Operation vacuum, ion, injection, luminosity 2977
 
  • H.-C. Hseuh, M. Mapes, L. Smart, R.J. Todd, D. Weiss
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy.

With increasing ion beam intensity during recent RHIC operations, pressure rises of several decades were observed at most room temperature sections and at a few cold sections. The pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam ion induced desorption and have been one of the major intensity and luminosity limiting factors for RHIC. Improvement of the warm sections has been carried out in the last few years. Extensive in-situ bakes, additional UHV pumping, anti-grazing ridges and beam tube solenoids have been implemented. Several hundred meters of NEG coated beam pipes have been installed and activated. Vacuum monitoring and interlock were enhanced to reduce premature beam aborts. Preliminary measures, such as pumping before cool down to reduce monolayer condensates, were also taken to suppress the pressure rises in the cold sections. The effectiveness of these measures in reducing the pressure rises during machine studies and during physics runs are discussed and summarized.

 
 
RPPE050 Development of NEG Coating for RHIC Experimental Beamtubes cathode, vacuum, ion, luminosity 3120
 
  • D. Weiss, P. He, H.-C. Hseuh, R.J. Todd
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract No. DE-AC02-98CH10886 under the auspices of the U.S. Department of Energy.

As RHIC beam intensity increases beyond original scope, pressure rises in some regions have been observed. The luminosity limiting pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam induced desorption. Non-Evaporable Getter (NEG) coated beampipes have been proven effective to suppress pressure rise in synchrotron radiation facilities. Standard beampipes have been NEG coated by a vendor and added to many RHIC UHV regions. BNL is developing a cylindrical magnetron sputtering system to NEG coat special beryllium beampipes installed in RHIC experimental regions. It features a hollow, liquid cooled cathode producing power density of 500W/m and deposition rate of 5000 Angstrom/hr on 7.5cm OD beampipe. The cathode, a titanium tube partially covered with zirconium and vanadium ribbons, is oriented for horizontal coating of 4m long chambers. Ribbons and magnets are arranged to provide uniform sputtering distribution and deposited NEG composition. Vacuum performance of NEG coated pipes was measured. Coating analysis includes energy dispersive spectroscopy, auger electron spectroscopy and scanning electron microscopy. System design, development, and analysis results are presented.

 
 
RPPE052 Application of Comb-Type RF-Shield to Bellows Chambers and Gate Valves vacuum, positron, impedance, injection 3203
 
  • Y. Suetsugu, K.-I. Kanazawa, N. Ohuchi, K. Shibata, M. Shirai
    KEK, Ibaraki
  A comb-type RF-shield, which was recently proposed for high current accelerators, was experimentally applied to bellows chambers and gate valves. The comb-type RF-shield has a structure of nested comb teeth, and has higher thermal strength and lower impedance than usual finger-type RF shields. The shield is suitable for future high intensity accelerators, such as particle factories aiming a luminosity of 1·1035 - 36 /cm2 /s. Seven bellows chambers with a circular or a racetrack cross section had been installed in the KEKB (KEK B-factory) positron ring since 2003 in series. Some bellows chambers are forced to bend up to 20 mrad during the beam operation. No significant problem had been found with a stored beam current up to 1.6 A (1.25 mA/bunch). On the other hand, a circular-type gate valve with the comb-type RF shield will be installed in the ring in January, 2005. Structures, properties and results of the beam test of the bellows chamber and the gate valve are discussed.  
 
RPPE053 R&D Status of Vacuum Components for the Upgrade of KEKB vacuum, positron, impedance, photon 3256
 
  • Y. Suetsugu, H. Hisamatsu, K.-I. Kanazawa, N. Ohuchi, K. Shibata, M. Shirai
    KEK, Ibaraki
  An upgrade plan of the KEK B-factory (KEKB), Super KEKB, aiming a luminosity over 1·1035 /cm2 /s has been discussed in KEK. To achieve the high luminosity, the stored beam currents are 4.2 - 9.4 A and the bunch length is 3 mm. In designing the vacuum system of the Super KEKB, therefore, the main issues are how to manage the resultant highly intense synchrotron radiation (SR) power, and how to reduce the beam impedance. The R&Ds for basic vacuum components, such as a beam duct, a bellows chamber, a connection flange, a collimator, a high-capacity pump and so on, are now undergoing to deal with the problems. For examples, a copper beam duct with an antechamber was manufactured to reduce the power density of SR, and to suppress the electrons around the beam for the positron ring. The test chamber was installed in the positron ring of KEKB and tested with a beam. Bellows chambers with a newly developed RF-shield were also installed in the ring and the property was investigated. A special connection flange with little step or gap inside was developed and examined in a test bench. The designs of these components and the results of tests are presented and discussed.  
 
RPPE057 Resistive Wall Wakefield in the LCLS Undulator undulator, impedance, resonance, simulation 3390
 
  • K.L.F. Bane, G.V. Stupakov
    SLAC, Menlo Park, California
  Funding: Work supported by the U.S. Department of Energy, contract DE-AC03-76SF00515.

In the Linac Coherent Light Source (LCLS), a short, intense bunch (rms length 20 microns, bunch charge 1 nC) will pass through a small, long undulator beam pipe (radius 2.5 mm, length 130 m). The wakefields in the undulator, particularly the resistive wall wake of the beam pipe, will induce an energy variation along the bunch, a variation that needs to be kept to within a few times the Pierce parameter for all beam particles to continue to lase. Earlier calculations included the short-range resistive wall wake, but did not include the frequency dependence of conductivity (ac conductivity) of the beam pipe walls. We show that for copper and for the LCLS bunch structure, including the ac conductivity results in a very large effect. We show that the effect can be ameliorated by choosing aluminum and also by taking a flat, rather than round, beam pipe chamber (if the vertical aperture is fixed). The effect of the (high frequency) anomalous skin effect is also considered.

 
 
RPPE058 Successful RF and Cryogenic Tests of the SOLEIL Cryomodule insertion, coupling, insertion-device, synchrotron 3438
 
  • P. Marchand, M. Louvet, M. Louvet-Monsanglant, K. Tavakoli, C. Thomas-Madec
    SOLEIL, Gif-sur-Yvette
  • L. Arnaudon, O. Brunner, R. Losito, P. Maesen, E. Montesinos, G. Pechaud, M.P. Prax
    CERN, Geneva
  • P. Bosland, P. Bredy, S. Chel, G. Devanz
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  In the Storage Ring (SR) of the Synchrotron SOLEIL light source, two cryomodules will provide the maximum power of 600 kW required at the nominal energy of 2.75 GeV with the full beam current of 500 mA and all the insertion devices. A cryomodule prototype, housing two 352 MHz superconducting single-cell cavities with strong damping of the Higher Order Modes has been built and successfully tested in the ESRF. Even though the achieved performance (3 MV and 380 kW) does meet the SOLEIL requirement for the first year of operation, it was decided to upgrade the cryomodule prototype before its implementation in the SR. Modifications of the internal cryogenic system as well as the input power and dipolar HOM couplers required complete disassembling, reassembling and testing of the cryomodule, which were carried out at CERN. This refurbishment program, which was achieved in the framework of a collaboration between SOLEIL, CEA and CERN, is reported in this paper. A second cryomodule, similar to the modified prototype, is under manufacturing and will be implemented in the SR by the end of 2006.  
 
RPPE067 Design and Fabrication of an FEL Injector Cryomodule SNS, gun, booster, vacuum 3724
 
  • J. Rathke, A. Ambrosio, H. Bluem, M.D. Cole, E. Peterson, T. Schultheiss, A.M.M. Todd
    AES, Medford, NY
  • I.E. Campisi, E. Daly, J. Hogan, J. Mammosser, G. Neil, J.P. Preble, R.A. Rimmer, C.H. Rode, T.E. Whitlatch, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  • J.S. Sekutowicz
    DESY, Hamburg
  Funding: This work is supported by NAVSEA, MDA, and SMDC.

Advanced Energy Systems has recently completed the design of a four cavity cryomodule for use as an FEL injector accelerator on the JLAB Injector Test Stand. Fabrication is nearing completion. Four 748.5 MHz single cell superconducting cavities have been completed and are currently at Jefferson Lab for final processing and test prior to integration in the module. This paper will review the design and fabrication of the cavities and cryomodule.

 
 
RPPE075 Injector Electronics for Multi-Turn Operation of the University of Maryland Electron Ring (UMER) dipole, injection, beam-losses, cathode 3952
 
  • M. Holloway, T.F. Godlove, P.G. O'Shea, B. Quinn, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by U.S. Department of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

Progress is described toward the development of pulse generators required for injection and extraction of the University of Maryland Electron Ring (UMER). The geometry, described elsewhere, employs a fast ironless dipole at the junction of a Y-shaped section of the ring. The dipole as developed has an inductance of 600 nH. The required +21 A, long pulse generator for multi-turn operation is installed. A pulser providing -42 A for deflection in the opposite sense during injection is under development. It must have a fall time of ~100 ns in view of the 200 ns circulation time for the beam. A similar pulser, having a 100 ns risetime is required for beam extraction. The fast pulsers employ MOSFET switches.

 
 
RPPE076 Overview of Electrical Systems for the University of Maryland Electron Ring (UMER) dipole, quadrupole, injection, cathode 3988
 
  • B. Quinn, G. Bai, S. Bernal, T.F. Godlove, I. Haber, J.R. Harris, M. Holloway, H. Li, J.G. Neumann, P.G. O'Shea, K. Tian, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by the United States Department of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

Commissioning of the University of Maryland Electron Ring (UMER) is underway (see general abstract on UMER). We discuss the various electrical systems of UMER. The power system includes 114 supplies for 70 air-core magnetic quadrupoles, 36 bending dipoles and 30+ steering dipoles as well as earth's field compensating coils. Systems for data collection comprise multiplexers and fast digitizers for diagnostics including 15 fast beam position monitors (BPMs)and video capture from fluorescent screen monitors. Several pulsers have been built in-house for injection and extraction magnets. The stringent timing schemes are also presented.

 
 
RPPP011 Different Options for Dispersion Free Steering in the CLIC Main Linac linac, emittance, positron, quadrupole 1251
 
  • D. Schulte
    CERN, Geneva
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395).

Sophisticated beam-based alignment is essential in future linear colliders to preserve the beam emittance during the transport through the main linac. One such method is dispersion free steering. In this paper different options to implement this method are discussed, based on the use of different accelerating gradients, RF phases and bunch particle types during a beam pulse.

 
 
RPPP013 Tests of the FONT3 Linear Collider Intra-Train Beam Feedback System at the ATF feedback, kicker, linear-collider, collider 1359
 
  • P. Burrows, G.B. Christian, C.C. Clarke, A.F. Hartin, H.D. Khah, S. Molloy, G.R. White
    Queen Mary University of London, London
  • J.C. Frisch, T.W. Markiewicz, D.J. McCormick, M.C. Ross, S. Smith, T.J. Smith
    SLAC, Menlo Park, California
  • A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • C. Perry
    OXFORDphysics, Oxford, Oxon
  We report preliminary results of beam tests of the FONT3 Linear Collider intra-train position feedback system prototype at the Accelerator Test Facility at KEK. The feedback system incorporates a novel beam position monitor (BPM) processor with a latency below 5 nanoseconds, and a kicker driver amplifier with similar low latency. The 56 nanosecond-long bunchtrain in the ATF extraction line was used to test the prototype with delay-loop feedback operation. The achieved latency represents a demonstration of intra-train feedback on timescales relevant even for the CLIC Linear Collider design.  
 
RPPP015 Reconstruction of IP Beam Parameters at the ILC from Beamstraahlung photon, simulation, radiation, luminosity 1446
 
  • G.R. White, G.R. White
    SLAC, Menlo Park, California
  Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899.

The luminosity performance of the ILC will be very sensitive to the parameters of the colliding bunches. Only some of these parameters can be measured using planned instrumentation. This analysis aims to access some of the colliding beam parameters not available by other means and to improve on the resolution of those that are. GUINEA-PIG is used to simulate the beam-beam interactions and produce beamstrahlung radiation (e+/e- pairs and photons). These are tracked to a simulation of the low-angle Beam Calorimeter and a photon detector and event shapes are produced. A Taylor map is produced to transform from the event shapes to the simulated beam parameters. This paper reports on the progress of this analysis, examining the usefulness of the proposed fitting technique.

 
 
RPPP029 Analysis of Positron Collection in Linear Collider positron, target, damping, emittance 2101
 
  • Y.K. Batygin
    SLAC, Menlo Park, California
  Funding: Work is supported by Department of Energy Contract No. DE-AC02-76SF00515

In the Linear Collider, the positron capture system includes a positron production target, a flux concentrator, and a linac to accelerate positrons up to the injection energy of the positron damping ring. Two schemes for positron production have been studied: (i) a conventional approach with an electron beam interacting with a high-Z target and (ii) polarized positron production using polarized photons generated in a helical undulator by electron beam which then interact with a positron production target. Efficiency of positron collector is defined by positron yield which is a ratio of positrons accepted into damping ring to the number of incident electrons or photons. The capture system has been optimized to insure high positron yield into the 6-dimensional acceptance of the damping ring keeping the high value of positron polarization. Various parameters affecting the positron capture are analyzed.

 
 
RPPP038 Electron-Cloud Effects in Transport Lines of a Normal Conducting Linear Collider positron, focusing, vacuum, resonance 2527
 
  • J. Wu, M.T.F. Pivi, T.O. Raubenheimer, A. Seryi
    SLAC, Menlo Park, California
  Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.

In the transport lines of a normal conducting linear collider, the long positron bunch train can generate an electron cloud which can then amplify intra-train offsets. This is a transient effect which is similar to but different from the electron-cloud driven coupled bunch instabilities in a positron storage ring. In this paper, we study this phenomenon both analytically and via numerical simulation. Some criterion on the critical cloud density with respect to given collider parameters is discussed.

 
 
RPPP039 Heat Deposition in Positron Sources for ILC target, positron, photon, shielding 2574
 
  • V. Bharadwaj, R. Pitthan, J. Sheppard, H. Vincke, J.W. Wang
    SLAC, Menlo Park, California
  Funding: Work supported by Department of Energy contract DE-AC02-76SF00515.

In an ILC positron source, multi-GeV electrons or multi-MeV photons impinge on a metal target. In either case, the incoming beam power is hundreds of kilowatts. Various computer programs - such as FLUKA or MARS – can calculate how the incoming beam showers in the target and can track the particle showers through the positron source system. The incoming energy ends up as heat in the various positron source elements. This paper presents results from such calculations and their impact on the design of a positron source for the ILC.

 
 
RPPP045 Single-Bunch Instability Driven by the Electron Cloud Effect in the Positron Damping Ring of the International Linear Collider dipole, single-bunch, simulation, damping 2884
 
  • M.T.F. Pivi, T.O. Raubenheimer
    SLAC, Menlo Park, California
  • A.F. Ghalam
    USC, Los Angeles, California
  • K.C. Harkay
    ANL, Argonne, Illinois
  • K. Ohmi
    KEK, Ibaraki
  • R. Wanzenberg
    DESY, Hamburg
  • A. Wolski
    LBNL, Berkeley, California
  • F. Zimmermann
    CERN, Geneva
  Funding: Work supported by the U.S. DOE under contracts DE-AC02-76SF00515.

With the recommendation that the future International Linear Collider (ILC) should be based on superconducting technology, there is considerable interest in exploring alternate designs for the damping rings (DR). The TESLA design was 17 km in circumference with a "dog-bone" configuration. Two other smaller designs have been proposed that are 6 km and 3 km in length. In the smaller rings, collective effects may impose the main limitations. In particular for the positron damping ring, an electron cloud may be produced by ionization of residual gas or photoelectrons and increase through the secondary emission process. The build-up and development of an electron cloud is more severe with the higher average beam current in the shorter designs. In this paper, we present recent computer simulation results for the electron cloud build-up and instability thresholds for the various DR configurations.

 
 
RPPP046 An L-Band Polarized Electron PWT Photoinjector for the International Linear Collider (ILC) cathode, vacuum, emittance, simulation 2902
 
  • D. Yu, A. Baxter, P. Chen, M. Lundquist, Y. Luo, A. S. Smirnov
    DULY Research Inc., Rancho Palos Verdes, California
  Funding: Work supported by DOE SBIR Grant No. DE-FG02-03ER83846.

A multi-cell, standing-wave, L-band, p-mode, plane-wave-transformer (PWT) photoinjector with an integrated photocathode in a novel linac structure is proposed by DULY Research Inc. as a polarized electron source. The PWT photoinjector is capable of operation in ultra high vacuum and moderate field gradient. Expected performance of an L-band polarized electron PWT injector operating under the parameters for the International Linear Collider is presented. The projected normalized transverse rms emittance is an order of magnitude lower than that produced with a polarized electron dc gun followed by subharmonic bunchers.

 
 
RPPT001 The BESSY Soft X-Ray FEL User Facility photon, undulator, linac, simulation 746
 
  • D. Kraemer
    BESSY GmbH, Berlin
  Funding: Funded by Zukunftsfonds Berlin.

The user requests for an optimized 2nd generation FEL facility in the VUV to soft X-ray range demand for ultra short photon pulses (t = 20 fs) at a peak power of several GW. A high shot to shot reproducibility of the pulse shape and pulse power allowing for fs-synchronization for pump-probe experiments is feasible in a seeded FEL approach. Free selectable photon polarization and wavelength tuning is essential for any 2nd generation FEL source like the proposed BESSY-Soft X-ray FEL user facility. Freely selectable pulse repetition rates and freely selectable pulse patterns, including fast switching to different parallel operating FEL-Lines are necessary ingredients, feasible with a suitable injector in combination with a CW-superconducting linac. The status of the BESSY HGHG-FEL project will be reviewed.

 
 
RPPT002 Harmonic Content of the BESSY FEL Radiation radiation, undulator, bunching, simulation 829
 
  • A. Meseck, K. Goldammer
    BESSY GmbH, Berlin
  Funding: Funded by Zukunftsfonds Berlin.

BESSY proposes a linac-based cascaded High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) multi-user facility. The BESSY soft X-ray FEL will consist of three undulator lines. The associated tunable lasers will cover the spectral range of 230nm to 460nm. Two to four HGHG stages reduce the seed wavelength to the desired radiation range of 1.24nm < λ < 51nm. The harmonic content of the high-intensity radiator output can be used to reduce the number of necessary HGHG stages. Moreover the higher harmonic content of the final output extends the offered spectral range and thus is of high interest for the user community. In this paper, the higher harmonic content of the final output as well as of the output of several radiators are investigated. The main parameters such as output power, pulse duration and bandwidth as well as their suitability for seeding are discussed.

 
 
RPPT012 Layout of the Diagnostic Section for the European XFEL emittance, lattice, diagnostics, radiation 1285
 
  • C. Gerth, Mr. Roehrs, H. Schlarb
    DESY, Hamburg
  Fourth generation synchrotron light sources, such as the European Free Electron Laser (XFEL) project, are based on an exponential gain of the radiation amplification in a single pass through a long undulator magnet. To initiate the FEL process and to reach staturation, precise monitoring and control of the electron beam parameters is mandatory. Most challenging are the longitudinal compression processes in magnetic chicanes of the high brightness electron bunch emitted from an RF photo-injector. To measure and control the beam properties after compression, careful consideration must be given to the design of a diagnostic section and the choice of beam monitors. In this paper, the proposed layout of the XFEL diagnostics beamline is discussed and emphasis is put on the possibility of monitoring on-line the slice energy spread, slice emittance and longitudinal bunch profile with high accuracy.  
 
RPPT017 Wake Field Effect on the SASE Performance of PAL XFEL undulator, radiation, linac, emittance 1549
 
  • J.-S. Oh, I.S. Ko, T.-Y. Lee, W. Namkung
    PAL, Pohang, Kyungbuk
  Funding: Supported by the POSCO and the MOST, Korea.

The PAL XFEL will supply coherent radiations from VUV to X-rays. X-ray FEL for 0.3 nm lasing requires a 3-GeV driver linac and a 60-m long in-vacuum undulator with a narrow variable gap. The linac should supply highly bright beams with emittance of 1.2 mm-mrad, a peak current of 3.5 kA, and a low energy spread of 0.03%. The beam quality is degraded along the undulator trajectory due to the energy loss, the wake field, and the magnetic field errors, etc. Especially the wake field effect is most sensitive parameter due to the narrow gap of the undulator. The preliminary design details of undulators for PAL-XFEL are presented with parametric analysis. The temporal SASE performance is analyzed using simulation tools such as GENESIS and SIMPLEX.

 
 
RPPT019 Start to End Simulations of the ERL Prototype at Daresbury Laboratory simulation, linac, wiggler, booster 1643
 
  • C. Gerth, M.A. Bowler, B.D. Muratori, H.L. Owen, N. Thompson
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • B. Faatz
    DESY, Hamburg
  • B.W.J. McNeil
    Strathclyde University, Glasgow
  Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will serve as a research and development facility for the study of beam dynamics and accelerator technology important to the design and construction of the proposed 4th Generation Light Source (4GLS) project. Two major objectives of the ERLP are the demonstration of energy recovery and of energy recovery from a beam disrupted by an FEL interaction as supplied by an infrared oscillator system. In this paper we present start-to-end simulations of the ERLP including such an FEL interaction. The beam dynamics in the high-brightness injector, which consists of a DC photocathode gun and a superconducting booster, have been modelled using the particle tracking code ASTRA. After the booster the particles have been tracked with the code GPT which includes space charge in the injector line at 8.3 MeV. The 3D code GENESIS 1.3 was used to model the FEL interaction with the electron beam at 35 MeV.  
 
RPPT021 Inducing Strong Density Modulation with Small Energy Dispersion in Particle Beams and the Harmonic Amplifier Free Electron Laser radiation, bunching, undulator, emittance 1718
 
  • B.W.J. McNeil, G.R.M. Robb
    Strathclyde University, Glasgow
  • M.W. Poole
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Funding: We acknowledge the support of the European Union's EUROFEL Design Study, CCLRC, and the Scottish Universities Physics Alliance.

We present a possible method of inducing a periodic density modulation in a particle beam with little increase in the energy dispersion of the particles. The flow of particles in phase space does not obey Liouville's Theorem. The method relies upon the Kuramoto-like model of collective synchronism found in free electron generators of radiation, such as Cyclotron Resonance Masers and the Free Electron Laser. For the case of an FEL interaction, electrons initially begin to bunch and emit radiation energy with a correlated energy dispersion which is periodic with the FEL ponderomotive potential. The relative phase between potential and particles is then changed by approximately 180 degrees. The particles continue to bunch, however, there is now a correlated re-absorption of energy from the field. We show that, by repeating this relative phase change many times, a significant density modulation of the particles may be achieved with only relatively small energy dispersion. A similar method of repeated relative electron/radiation phase changes is used to demonstrate supression of the fundamental growth in a high gain FEL so that the FEL lases at the harmonic only.

 
 
RPPT022 Optics for High Brightness and High Current ERL Project at BNL gun, dipole, emittance, linac 1775
 
  • D. Kayran, I. Ben-Zvi, R. Calaga, X.Y. Chang, J. Kewisch, V. Litvinenko
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy and partially funded by the US Department of Defence

An energy recovery linac (ERL), under development at Brookhaven National Laboratory [1,2], will push ERLs further towards high current and high brightness beams. This R&D ERL will operate in two modes: a high current mode and a high charge mode. In this paper we present a lattice of the machine and PARMELA simulations from the cathode to the beam dump. We discuss the design considerations and present main parameters for various modes of operation.

 
 
RPPT024 Doubling the Intensity of an ERL Based Light Source linac, undulator, wiggler, synchrotron 1862
 
  • A. Hutton
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by the U.S. DOE under Contract No. DE-AC05-84ER40150.

A light source based on an Energy Recovered Linac (ERL)* consists of a superconducting linac and a transfer line that includes wigglers and undulators to produce the synchrotron light. The transfer line brings the electrons bunches back to the beginning of the linac so that their energy can be recovered when they traverse the linac a second time, ????out of phase. There is another interesting condition when the length of the transfer line is (n±1/4) ?. In this case, the electrons drift through on the zero RF crossing, and make a further pass around the transfer line, effectively doubling the circulating current in the wigglers and undulators. On the third pass through the linac, they will be decelerated and their energy recovered. The longitudinal focusing at the zero crossing is a problem, but it can be canceled if the drifting beam sees a positive energy gradient for the first half of the linac and a negative gradient for the second half (or vice versa). This paper presents a proposal to use a double chicane at the center of the linac to provide this focusing inversion for the drifting beam while leaving the accelerating and decelerating beams on crest.

*G. R. Neil et al., Phys. Rev. Let. 84, 662 2000.

 
 
RPPT026 Status of a Plan for an ERL Extension to CESR linac, emittance, undulator, optics 1928
 
  • G. Hoffstaetter, S.A. Belomestnykh, J.S.-H. Choi, Z. Greenwald, M. Liepe, H. Padamsee, D. Sagan, C. Song, R.M. Talman, M. Tigner
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • I.V. Bazarov, K.W. Smolenski
    Cornell University, Ithaca, New York
  • D.H. Bilderback, M.G. Billing, S.M. Gruner, Y. Li, C.K. Sinclair
    Cornell University, Department of Physics, Ithaca, New York
  Funding: Cornell University.

We describe the status of plans to build an Energy-Recovery Linac (ERL) X-ray facility at Cornell University. This 5 GeV ERL is an upgrade of the CESR ring that currently powers the Cornell High Energy Synchrotron Source (CHESS). Due to its very small electron-beam emittances, it would dramatically improve the capabilities of the light source and result in X-ray beams orders of magnitude better than any existing storage ring light source. The emittances are based upon simulations for currents that are competitive with ring-based sources. The ERL design that is presented has to allow for non-destructive transport of these small emittances. The design includes a series of X-ray beamlines for specific areas of research. As an upgrade of the existing storage ring, special attention is given to reuse of many of the existing ring components. Options of bunch compression are discussed, tolerances for emittance growth are specified, and simulations of the beam-breakup instability and methods of increasing its threshold current are shown. This planned upgrade illustrates how other existing storage rings could be upgraded as ERL light sources with vastly improved beam qualities.

 
 
RPPT027 Considerations on Beam Quality Control in MIT X-Ray FEL linac, laser, feedback, emittance 1961
 
  • D. Wang, W. Graves, D. Wang, T. Zwart
    MIT, Middleton, Massachusetts
  • P. Emma, J. Wu
    SLAC, Menlo Park, California
  • G. Huang
    LBNL, Berkeley, California
  Funding: U.S. Department of Energy.

The next generation of x-ray FEL requires very high quality electron beams for producing unprecedented x-ray radiations. In proposed x-ray FEL facilities, especially those that use multi-stage high gain high harmonic (HGHG) principle to obtain coherence in both transverse and longitudinal dimensions, the arrival timing of electron bunches must be very precise to ensure the seed laser overlap the desired sections of the electron bunch. A scheme is proposed to achieve 10s fs level of arrival timing control level.

 
 
RPPT028 Free Electron Lasers with Slowly Varying Beam and Undulator Parameters undulator, vacuum, radiation, simulation 2059
 
  • Z. Huang, G.V. Stupakov
    SLAC, Menlo Park, California
  The performance of a free electron lasers (FEL) is affected when the electron beam energy varies alone the undulator as would be caused by vacuum pipe wakefields and/or when the undulator strength parameter is tapered in the small signal regime until FEL saturation. In this paper, we present a self-consistent theory of FELs with slowly-varying beam and undulator parameters. A general method is developed to apply the WKB approximation to the beam-radiation system by employing the adjoint eigenvector that is orthogonal to the eigenfunctions of the coupled Maxwell-Vlasov equations. This method may be useful for other slowly varying processes in beam dynamics.  
 
RPPT031 Recent Results from and Future Plans for the VISA II SASE FEL radiation, simulation, diagnostics, undulator 2167
 
  • G. Andonian, R.B. Agustsson, P. Frigola, A.Y. Murokh, C. Pellegrini, S. Reiche, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • M. Babzien, I. Ben-Zvi, V. Litvinenko, V. Yakimenko
    BNL, Upton, Long Island, New York
  • I. Boscolo, S. Cialdi, A.F. Flacco
    INFN-Milano, Milano
  • M. Ferrario, L. Palumbo, C. Vicario
    INFN/LNF, Frascati (Roma)
  • J.Y. Huang
    PAL, Pohang, Kyungbuk
  As the promise of X-ray Free Electron Lasers (FEL) comes close to realization, the creation and diagnosis of ultra-short pulses is of great relevance in the SASE FEL (Self-Amplified Spontaneous Emission) community. The VISA II (Visible to Infrared SASE Amplifier) experiment entails the use of a chirped electron beam to drive a high gain SASE FEL at the Accelerator Test Facility (ATF) in Brookhaven National Labs (BNL). The resulting ultra-short pulses will be diagnosed using an advanced FROG (Frequency Resolved Optical Gating) technique, as well as a double differential spectrum (angle/wavelength) diagnostic. Implementation of sextupole corrections to the longitudinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-to-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole correction, the resulting high gain lasing, and computational analysis are briefly reported.  
 
RPPT032 High Current Energy Recovery Linac at BNL linac, emittance, lattice, gun 2242
 
  • V. Litvinenko, D.B. Beavis, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, R. Connolly, D.M. Gassner, H. Hahn, A. Hershcovitch, H.-C. Hseuh, P.D.J. Johnson, D. Kayran, J. Kewisch, R.F. Lambiase, G.J. Mahler, G.T. McIntyre, W. Meng, T.C.N. Nehring, T. Nicoletti, B. Oerter, D. Pate, J. Rank, T. Rao, T. Roser, T. Russo, J. Scaduto, K. Smith, N.W.W. Williams, K.-C. Wu, V. Yakimenko, K. Yip, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • H. Bluem, A. Burger, M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • J.R. Delayen, L. W. Funk, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy.

We present the design and the parameters of a small Energy Recovery Linac (ERL) facility, which is under construction at BNL. This R&D facility has goals to demonstrate CW operation of ERL with average beam current in the range of 0.1 - 1 ampere, combined with very high efficiency of energy recovery. The possibility for future up-grade to a two-pass ERL is being considered. The heart of the facility is a 5-cell 703.75 MHz super-conducting RF linac with HOM damping. Flexible lattice of ERL provides a test-bed for testing issues of transverse and longitudinal instabilities and diagnostics of intense CW e-beam. We present the status and plans for this facility.

 
 
RPPT033 Potential Use of eRHIC’s 10-to-20 GeV ERL for FELs and Light Sources radiation, linac, synchrotron, synchrotron-radiation 2266
 
  • V. Litvinenko, I. Ben-Zvi
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy.

One of the designs of a future electron-hadron collider, eRHIC, is based on a 5-10 GeV high current energy-recovery linac (ERL) with possible extension of its energy to 20 GeV. This ERL will operate with high brightness electron beams, which naturally match requirements for X-ray FELs and other next generation light sources. In this paper we discuss possible scenarios of using the eRHIC ERL in parasitic and dedicated mode for SASE, HGHG and oscillator X-ray FELs.

*http://www.agsrhichome.bnl.gov/eRHIC/, Appendix A: Linac-Ring Option

 
 
RPPT034 High-Resolution Undulator Measurements using Angle-Integrated Sponteneous Radiation undulator, photon, radiation, simulation 2342
 
  • B.X. Yang
    ANL, Argonne, Illinois
  Funding: Work supported by U. S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38.

The Linac Coherent Light Source (LCLS) is a fourth-generation light. Its proper operation requires a stringently controlled undulator field. The tolerance for the field parameter K is less than 1.5 × 10-4 for all thirty-three undulator segments totaling 112 meters. Even with the high quality of the LCLS electron beam (x- and y-emittance ~ 44 pm, energy spread ~0.03%), the fluctuation of the electron energy (~0.05%) presents a serious challenge to measurement techniques based on electron or x-ray beams. We propose a differential measurement technique that makes use of the angle-integrated spontaneous radiation intensities from two undulator segments. When the x-ray beams emitted from the two undulator segments are separated but allowed to pass through the same monochromator, the two beam intensities will change almost identically with the change of electron beam energy. As a result, the intensity difference becomes a very sensitive and reliable measure of the difference of the two undulators’ K-parameters. Results of comprehensive numerical simulations show that differences in the range of delta-K/K ~ 10-5 can be resolved, well within the tolerance for the LCLS operation.

 
 
RPPT035 Optimization of the LCLS X-Rray FEL Output Performance in the Presence of Strong Undulator Wakefields undulator, vacuum, simulation, radiation 2396
 
  • S. Reiche
    UCLA, Los Angeles, California
  • K.L.F. Bane, P. Emma, Z. Huang, H.-D. Nuhn, G.V. Stupakov
    SLAC, Menlo Park, California
  • W.M. Fawley
    LBNL, Berkeley, California
  Funding: The work was supported by the DOE Contract No. DE-AC02-76SF00515.

The Linac Coherent Light Source (LCLS) Free-Electron Laser will operate in the wavelength range of 1.5 to 15 Angstroms. Energy loss due to wakefields within the long undulator can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive component is the most critical and depends upon the chamber material (e.g. Cu) and its radius. To study the expected performance in the presence of these wakefields, we make a series of "start-to-end" simulations with tracking codes PARMELA and ELEGANT and time-dependent FEL simulation codes Genesis 1.3 and Ginger. We discuss the impact of the wakefield on output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation obtained with a slight z dependent taper in the undulator field. We compare these results to those obtained by decreasing the bunch charge or increasing the vacuum chamber radius. We also compare our results to those predicted in concurrent analytical work.

 
 
RPPT036 200 MeV Linac Upgrade for FEL linac, gun, cathode, klystron 2464
 
  • Y.G. Zhou, S. Dong, H. He, L.G. Li
    USTC/NSRL, Hefei, Anhui
  The present status of Hefei 200 MeV RF linac are given. By upgrading its present thermal cathode system into the photo cathode system and implement RF phase locked system, using Hefei 200 MeV RF linac as FEL driver is investigated.  
 
RPPT037 Technique for the Generation of Attosecond X-Ray Pulses Using an FEL laser, undulator, radiation, background 2506
 
  • G. Penn, A. Zholents
    LBNL, Berkeley, California
  Funding: This work was supported by the Office of Science, High Energy Physics, U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

We describe a technique for the generation of an isolated burst of X-ray radiation with a duration of ~100 attoseconds in a free electron laser (FEL) employing self-amplified spontaneous emission. Our scheme relies on an initial interaction of the electron beam with an ultra-short laser pulse in a one-period wiggler followed by compression in a dispersive section. The result of this interaction is to create a sub-femtosecond slice of the electron beam with enhanced growth rates for FEL amplification. After many gain lengths through the FEL undulator, the X-ray output from this slice dominates the radiation of the entire bunch. We consider the impact of various effects on the efficiency of this technique. Different configurations are considered in order to realize various timing structures for the resulting radiation.

 
 
RPPT038 Phase Noise Characteristics of Fiber Lasers as Potential Ultra-Stable Master Oscillators laser, booster, radio-frequency, feedback 2521
 
  • A. Winter, P. Schmüser
    Uni HH, Hamburg
  • J. Chen, F.O. Ilday, F.X. Kaertner, J. Kim
    MIT, Cambridge, Massachusetts
  • H. Schlarb
    DESY, Hamburg
  Fourth-generation light sources, such as the European X-Ray free electron laser facility (XFEL) require timing signals distributed over distances of the order of kilometers with a timing jitter in the order of femtoseconds. The master clock for the proposed optical distribution system must operate with exceptionally low timing jitter. A promising approach is the use of a mode-locked laser that generates ultrastable pulses which are distributed via timing stabilized fiber links. Candidates for the pulse source are mode-locked Erbium doped fiber lasers, featuring very low high frequency noise. In this paper, we present a study of the phase noise of various fiber lasers in view of their applicability as laser-based master oscillators for femtosecond timing distributions.  
 
RPPT039 Stabilized Optical Fiber Links for the XFEL laser, feedback, resonance, polarization 2589
 
  • A. Winter
    Uni HH, Hamburg
  • J. Chen, F J. Grawert, F.O. Ilday, F.X. Kaertner, J. Kim
    MIT, Cambridge, Massachusetts
  • H. Schlarb, B. Schmidt
    DESY, Hamburg
  The timing synchronization scheme for the European X-Ray free electron laser facility (XFEL) is based on the generation and distribution of sub-picosecond laser pulses with actively stabilized repetition rate which are used to synchronize local RF oscillators. An integral part of the scheme is the distribution of the optical pulse stream to parts of the facility via optical fiber links. The optical path length of the fiber has to be stabilized against short-term and long-term timing jitter due to environmental effects, such as temperature drifts and acoustic vibrations, to better than 10 fs for distances ranging from tens of meters to several kilometers. In this paper, we present first experimental results for signal transmission through a km-long fiber link with femtosecond stability.  
 
RPPT040 Weak FEL Gain Detection with a Modulated Laser-Based Beam Heater undulator, laser, radiation, emittance 2636
 
  • P. Emma, Z. Huang, J. Wu
    SLAC, Menlo Park, California
  For an x-ray free-electron laser (FEL) such as the LCLS, the FEL gain signal is accompanied by spontaneous radiation with a significant power level. Detecting the weak FEL gain among the large spontaneous background in the early stage of the exponential growth or for a low quality electron beam is important in commissioning the FEL. In this paper, we describe a simple "lock-in" method of weak FEL gain detection by slowly modulating the laser power of a designated beam heater that controls the local energy spread of the electron beam. We present numerical modeling that shows the effectiveness of this method and discuss its implementation in the LCLS.  
 
RPPT051 Electron Model of Linear-Field FFAG acceleration, resonance, quadrupole, extraction 3173
 
  • S.R. Koscielniak
    TRIUMF, Vancouver
  • C. Johnstone
    Fermilab, Batavia, Illinois
  Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada.

A fixed-field alternating-gradient accelerator (FFAG) that employs only linear-field elements ushers in a new regime in accelerator design and dynamics. The linear-field machine has the ability to compact an unprecedented range in momenta within a small component aperture. With a tune variation which results from the natural chromaticity, the beam crosses many strong, uncorrec-table, betatron resonances during acceleration. Further, relativistic particles in this machine exhibit a quasi-parabolic time-of-flight that cannot be addressed with a fixed-frequency rf system. This leads to a new concept of bucketless acceleration within a rotation manifold. With a large energy jump per cell, there is possibly strong synchro-betatron coupling. A few-MeV electron model has been proposed to demonstrate the feasibility of these untested acceleration features and to investigate them at length under a wide range of operating conditions. This paper presents a lattice optimized for a 1.3 GHz rf, initial technology choices for the machine, and describes the range of experiments needed to characterize beam dynamics along with proposed instrumentation.

 
 
RPPT058 Kaon Monitoring Using the MiniBooNE Little Muon Counter kaon, secondary-beams, background, permanent-magnet 3435
 
  • T.L. Hart
    Colorado University at Boulder, Boulder, Colorado
  The Little Muon Counter (LMC) is a permanent magnet spectrometer designed to constrain electron neutrino backgrounds to the MiniBooNE experiment's neutrino oscillation signal. Electron neutrinos from kaon decay are a background to the MiniBooNE signal mode of the oscillation of muon neutrinos to electron neutrinos. MiniBooNE uses collisions of 8 GeV protons from the Fermilab Booster accelerator on a beryllium target to generate a secondary beam of pions and kaons that decay to produce a neutrino beam. The LMC constrains the kaon content of the meson beam, and thus the electron neutrinos from kaon decays, through momenta measurements of muons originating from decays of secondary beam kaons and pions. The LMC, located 7 degrees off-axis from the secondary beam, can distinguish pionic muons from kaonic muons kinematically. A description of the LMC components; analysis milestones including track momenta, muon identification penetration depth, track projection plots, and event displays; and the status of the LMC are presented.  
 
RPPT066 Electromigration Issues in High Current Horn target, secondary-beams, radiation, pulsed-power 3700
 
  • W. Zhang, S. Bellavia, J. Sandberg, N. Simos, J.E. Tuozzolo, W.-T. Weng
    BNL, Upton, Long Island, New York
  • B. Hseuh
    JHU, Baltimore, Maryland
  Funding: Work performed under the auspices of the U.S. Department of Energy.

The secondary particle focusing horn for the AGS neutrino experiment proposal is a high current and high current density device. The peak current of horn is 300 kA. At the smallest area of horn, the current density is near 8 kA/mm2. At very high current density, a few kA/mm2, the electromigration phenomena will occur. Momentum transfer between electrons and metal atoms at high current density causes electromigration. The reliability and lifetime of focusing horn can be severely reduced by electromigration. In this paper, we discuss issues such as device reliability model, incubation time of electromigration, and lifetime of horn.

 
 
RPPT074 Beam Characterizations at Femtosecond Electron Beam Facility cathode, linac, acceleration, radiation 3925
 
  • S. Rimjaem, V. Jinamoon, Mr. Kangrang, K. Kusoljariyakul, J. Saisut, C. Thongbai, T. Vilaithong
    FNRF, Chiang Mai
  • M.W. Rhodes, P. Wichaisirimongkol
    IST, Chiang Mai
  • H. Wiedemann
    SLAC, Menlo Park, California
  Funding: We are grateful to the Thailand Research Fund, the National Research Council of Thailand, the Thai Royal Golden Jubilee Scholarship, the U.S. Department of Energy, and the Hansen Experimental Physics laboratory of Stanford University.

The SURIYA project at the Fast Neutron Research Facility (FNRF) has been established and is being commissioning to generate femtosecond electron pulses. Theses short pulses are produced by a system consisting of an S-band thermionic cathode RF-gun, an alpha magnet as a magnetic bunch compressor, and a linear accelerator. The characteristics of its major components and the beam characterizations as well as the preliminary experimental results will be presented and discussed.

 
 
RPPT075 Generation of Femtosecond Electron and Photon Pulses radiation, photon, synchrotron, lattice 3946
 
  • C. Thongbai, V. Jinamoon, Mr. Kangrang, K. Kusoljariyakul, S. Rimjaem, J. Saisut, T. Vilaithong
    FNRF, Chiang Mai
  • M.W. Rhodes, P. Wichaisirimongkol
    IST, Chiang Mai
  • H. Wiedemann
    SLAC, Menlo Park, California
  Funding: We are grateful to the Thailand Research Fund, the National Research Council of Thailand, the Thai Royal Golden Jubilee Scholarship, the U.S. Department of Energy, and the Hansen Experimental Physics laboratory of Stanford University.

Femtosecond electron and photon pulses become a tool of interesting important to study dynamics at molecular or atomic levels. Such short pulses can be generated from a system consisting of an RF-gun with a thermionic cathode, an alpha magnet as a magnetic bunch compressor, and a linear accelerator. The femtosecond electron pulses can be used directly or used as sources to produce electromagnetic radiation of equally short pulses by choosing certain kind of radiation pruduction processes. At the Fast Neutron Research Facility (Thailand), we are especially interested in production of radiation in Far-infrared and X-ray regime. In the far-infrared wavelengths which are longer than the femtosecond pulse length, the radiation is emitted coherently producing intense radiation. In the X-ray regime, development of femtosecond X-ray source is crucial for application in ultrafast science.

 
 
ROPC006 Commissioning of Fermilab's Electron Cooling System for 8-GeV Antiprotons antiproton, vacuum, beam-losses, simulation 540
 
  • S. Nagaitsev, D.R. Broemmelsiek, A.V. Burov, K. Carlson, C. Gattuso, M. Hu, B.J. Kramper, T.K. Kroc, J.R. Leibfritz, L.R. Prost, S.M. Pruss, G.W. Saewert, C.W. Schmidt, A.V. Shemyakin, M. Sutherland, V. Tupikov, A. Warner
    Fermilab, Batavia, Illinois
  • W. Gai
    ANL, Argonne, Illinois
  • G.M. Kazakevich
    BINP SB RAS, Novosibirsk
  • S. Seletsky
    Rochester University, Rochester, New York
  A 4.3-MeV electron cooling system has been installed at Fermilab in the Recycler antiproton storage ring and is being currently commissioned. The cooling system is designed to assist accumulation of 8.9-GeV/c antiprotons for the Tevatron collider operations. This paper will report on the progress of the electron beam commissioning effort as well as on detailed plans of demonstrating the cooling of antiprotons.  
 
ROPC008 Experimental Progress in Fast Cooling in the ESR ion, emittance, injection, scattering 615
 
  • M. Steck, K. Beckert, P. Beller, B.  Franzke, F. Nolden
    GSI, Darmstadt
  The ESR storage ring at GSI is operated with highly charged heavy ions. Due to the high electric charge the ions interact much stronger with electromagnetic fields. Therefore both cooling methods which are applied to stored ions in the ESR, stochastic cooling and electron cooling, are more powerful than for singly charged particles. The experimental results exhibit cooling times for stochastic cooling of a few seconds. For cold ion beams, electron cooling provides cooling times which are one to two orders of magnitude smaller. The beams are cooled to beam parameters which are limited by intrabeam scattering. At small ion numbers, however, intrabeam scattering is suppressed by electron cooling, clear evidence was found that the ion beam forms a one-dimensional ordered structure, a linear chain of ions. The strengths of stochastic cooling and electron cooling are complementary and can be combined favorably. Stochastic cooling is employed for pre-cooling of hot secondary beams followed by electron cooling to provide ultimate beam quality. In a similar manner, first experiments with carbon ions have been performed to use electron cooling as a pre-cooling method in combination with laser cooling.  
 
FPAE001 Design Work for the High-Energy Storage Ring for Antiprotons of the Future GSI Project antiproton, storage-ring, target, injection 776
 
  • A. Lehrach, S. An, K. Bongardt, J. Dietrich, R. Eichhorn, B. Lorentz, R. Maier, S. Martin, D. Prasuhn, Y. Senichev, E.A. Senicheva, H. Stockhorst, R. Tölle, E. Zaplatin
    FZJ, Jülich
  • O. Boine-Frankenheim, A. Dolinskii, M. Steck
    GSI, Darmstadt
  • B. Gålnander, D. Reistad
    TSL, Uppsala
  • F.H. Hinterberger
    Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik,, Bonn
  The High-Energy Storage Ring (HESR) of the future international Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton cooler and storage ring in the momentum range from 1.5 to 15 GeV/c. The design work for the HESR is organized by a consortium with scientists from FZ Jülich, GSI Darmstadt and TSL Uppsala. An important feature of the new facility is the combination of phase space cooled beams with internal targets, resulting in demanding beam parameter in two operation modes: high luminosity mode with beam intensities up to few times 1011, and high resolution mode with a momentum spread down to 10-5, respectively. To reach these beam parameters very powerful phase space cooling is needed, utilizing high-energy electron cooling and high-bandwidth stochastic cooling. In this paper an overview of the design work is given, focusing on recent developments and planned R&D work.  
 
FPAE011 8 GeV H- Ions: Transport and Injection radiation, injection, proton, SNS 1222
 
  • W. Chou, A.I. Drozhdin, C. Hill, M.A. Kostin, J.-F. Ostiguy, Z. Tang
    Fermilab, Batavia, Illinois
  • H.C. Bryant
    UNM, Albuquerque, New Mexico
  • R.J. Macek
    LANL, Los Alamos, New Mexico
  • G. Rees
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • P.S. Yoon
    Rochester University, Rochester, New York
  Funding: Work supported by the Universities Research Association, INC. under contract with the U.S. Department of Energy NO. DE-AC02-76CH03000.

Fermilab is working on the design of an 8 GeV superconducting RF H- linac called the Proton Driver. The energy of the H- beam is an order of magnitude higher than any existing H- beams. This brings up a number of new challenges to the transport, stripping and injection into the next machine (the Main Injector), such as blackbody radiation stripping, magnetic field and residual gas stripping, Stark states of hydrogen atoms, foil stripping efficiency, single and multiple Coulomb scattering, energy deposition, foil heating and stress, radiation activation, collimation, jitter correction, etc. This paper will give a summary of these studies.*

*For details the reader is referred to FERMILAB-TM-2285-AD-T.

 
 
FPAE021 Alignment and Steering for Injection and Multi-Turn Operation of the University of Maryland Electron Ring (UMER) injection, quadrupole, dipole, alignment 1709
 
  • M. Walter, G. Bai, S. Bernal, I. Haber, M. Holloway, R.A. Kishek, P.G. O'Shea, B. Quinn
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by US Dept. of Energy grant numbers DE-FG02-94ER40855 and DE-FG02-92ER54178.

The injection line and main lattice for the University of Maryland Electron Ring (UMER) has been completed. The electron beam has been guided around the full 360 degrees of the ring. Beam steering and matching in the injection line is achieved with six quadrupole magnets and several small steering dipole magnets. The dipole component of an offset quadrupole and a pulsed dipole are used to achieve the 10 degree bend required from the injection line into the ring. The pulsed dipole is designed to operate with a short pulse (2 kV, -30 A, 100 ns flat top duration) for injection superimposed on a long pulse (300 V, 15 A, 20·10-6 s duration) for multiple beam passes. The beam is controlled in the recirculating ring with a regular lattice of 36 dipole and 72 quadrupole magnets. Initial experimental results of the beam transport and control will be presented.

 
 
FPAE025 Study of Slow Beam Extraction Through the Third Order Resonance with Transverse Phase Space Manipulation by a Mono-Frequency RFKO betatron, emittance, sextupole, extraction 1892
 
  • A. Miyamoto, H. Hama, F. Hinode, M. Kawai, K. Shinto, T. Tanaka
    LNS, Sendai
  An electron pulse-stretcher ring (STB ring) has a function which converts a pulse beam generated by RF linac into a quasi-continuous beam. Circulating beam in the ring is extracted by the third order resonance. Since there is no accelerating field in the ring, the beam approaches a transverse resonance condition due to synchrotron radiation loss with finite chromaticity. The extracted beam from the ring has some spread in time and space corresponding to injected beam from linac even if the injected beam is perfectly matched to the ring optics. However, the extracted beam emittance can be reduced by applying a phase space manipulation using an RF shaker. Under the influence of perturbation using an RF shaker driven by a mono-frequency, the betatron amplitude of circulating beam can be controlled in order to reduce the extracted beam emittance. The experimental results will be reported in this conference.  
 
FPAE036 Lattice Modification of a 1.2 GeV STB Ring for Generation of High Energy Gamma-Rays Using Internal Target Wire target, lattice, scattering, simulation 2458
 
  • F. Hinode, H. Hama, M. Kawai, A. Kurihara, A. Miyamoto, M. Mutoh, M. Nanao, Y. Shibasaki, K. Shinto, S. Takahashi, T. Tanaka
    LNS, Sendai
  A 1.2 GeV Stretcher-Booster Ring (STB ring) has been routinely operated at Laboratory of Nuclear Science (LNS), Tohoku University. The STB ring has functions of a pulse-beam stretcher and a booster-storage ring. In the booster-storage operation, high energy gamma-ray beam generated via bremsstrahlung from internal target wire is utilized for experiments of nuclear physics. Some fractions of circulating electrons are also deflected in the target wire due to Coulomb scattering without significant loss of the energy. The scattered electrons that are not getting out of the dynamic aperture once can circulate in the ring. Such electrons, however, would hit the chamber walls and supports of the target wire during further turns, because they have very large betatron amplitude. Consequently the Coulomb scattered electrons must be a source of significant background and may cause a degradation of gamma-ray beam quality. The quality of the gamma-ray beam has been improved by modifying the lattice functions of the ring, and we report the improvement in this conference.  
 
FPAE062 Beam Parameters of a Two-Sectional Electron Linac with the Injector Based on a Resonance System with Evanescent Oscillations linac, simulation, emittance, resonance 3567
 
  • V.V. Mytrochenko, M.I. Ayzatskiy, V.N. Boriskin, A. Dovbnya, I.V. Khodak, V.A. Kushnir, A. Opanasenko, S.A. Perezhogin, A.N. Savchenko, D.L. Stepin, V.I. Tatanov, Z.V. Zhiglo
    NSC/KIPT, Kharkov
  The S-band electron linac has been designed at NSC KIPT to cover an energy range from 30 to about of 100 MeV. The linac consists of a couple of the four-meter long piecewise homogeneous accelerating sections. Each section is supplied with RF power from a separate klystron. The peculiarity of the linac is using of the injector based on evanescent oscillations. The report presents both simulation results of self-consistent particle dynamics in the linac and results of measurement of beam parameters.  
 
FPAE070 A Collimation Scheme for Ions Changing Charge State in the LEIR Ring ion, vacuum, lattice, accumulation 3816
 
  • J. Pasternak, C.B. Bal, C. Carli, M. Chanel, E. Mahner
    CERN, Geneva
  Avalanche-like pressure rise and an associated decrease of the beam lifetime, caused by (i) beam loss due to charge exchange interactions with rest gas molecules and (ii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators operating at low energy. Capture of electrons from the electron cooler is another source of ion losses and thus, of pressure rise. The vacuum system of the LEIR ring has to be upgraded to reach the dynamical vacuum pressure in the low 10-12 Torr range necessary to reach design performance. A collimation system to intercept lost ions by absorber blocksmade of low beam induced outgassing material will be installed. This paper reviews the collimation scheme and simulations of beam loss patterns around the ring.  
 
FPAP001 Electron Cloud Build-Up Study for DAFNE positron, vacuum, simulation, wiggler 779
 
  • C. Vaccarezza, R. Cimino, A. Drago, M. Zobov
    INFN/LNF, Frascati (Roma)
  • G. Bellodi
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • K. Ohmi
    KEK, Ibaraki
  • M.T.F. Pivi
    SLAC, Menlo Park, California
  • G. Rumolo
    GSI, Darmstadt
  • D. Schulte, F. Zimmermann
    CERN, Geneva
  After the first experimental observations compatible with the presence of the electron cloud effect in the DAFNE positron ring, a more systematic study has been performed regarding the e-cloud build-up and related instability. The measured field map of the magnetic field has been taken into account in the simulation for elements present in the four 10 m long bending sections, representing 40% of the whole positron ring. The simulation results obtained with different codes are presented and compared with the recent experimental observations performed on the beam instabilities and the vacuum behavior of the positron ring.  
 
FPAP002 Experimental Determination of E-Cloud Simulation Input Parameters for DAFNE photon, simulation, vacuum, radiation 817
 
  • C. Vaccarezza, R. Cimino
    INFN/LNF, Frascati (Roma)
  • A. Giglia, N. Mahne
    ELETTRA, Basovizza, Trieste
  • S. Nannarone
    UNIMORE, Modena
  After the first experimental observations compatible with the presence of the electron-cloud effect in the DAFNE positron ring, an experimental campaign has been started to measure realistic parameters to be used in the simulation codes. Here we present a synchrotron radiation experiment on the photon reflectivity from the actual Al vacuum chamber of DAFNE (same material, roughness and surface cleaning as the one used to manufacture the ring) in the same energy range of photons produced by the accelerator itself. The derived experimental parameter has than been included in the e-cloud simulation codes and the obtained results confirm the relevance of the detailed knowledge of the input parameter to obtain reliable e-cloud simulations.  
 
FPAP003 Simulation Study of the Electron Cloud Instability in SuperKEKB simulation, positron, vacuum, synchrotron 868
 
  • H. Fukuma
    KEK, Ibaraki
  • L. Wang
    BNL, Upton, Long Island, New York
  The electron-cloud instability (ECI), especially a beam blowup caused by the single-bunch instability, is one of the most important issues faced at existing B factories. In SuperKEKB which is an upgrade plan of the KEK B factory, a positron beam will be stored in the high energy ring after LINAC upgrade to mitigate the ECI and ante-chambers will be effective to reduce the number of electrons. Nevertheless the ECI might be an issue of SuperKEKB because a large beam current of 4.1A will be stored with a short bunch spacing of 2ns. We performed a simulation of the cloud buildup by a program CLOUDLAND. The average electron density and the electron density at the center of a chamber were calculated both in drift space and in various magnetic fields. The result shows that a solenoid field is very effective for reducing the electron density. The simulated electron density will be compared with a threshold electron density of the strong head-tail instability.  
 
FPAP004 Simulation Analysis of Head-Tail Motion Caused by Electron Cloud simulation, feedback, dipole, betatron 907
 
  • K. Ohmi, J.W. Flanagan, H. Fukuma, S. Hiramatsu, H. Ikeda, M. Tobiyama
    KEK, Ibaraki
  • E. Perevedentsev
    BINP SB RAS, Novosibirsk
  Synchro-beta side band caused by electron cloud instability has been observed at KEK-B factory. The side-band appears between $νβ+νs$ and $νβ+2νs$ above the threshold of beam size blow up and disappear by applying solenoid field. The side-band is an evidence of strong head-tail instability caused by electron cloud. The side-band is characterized by positive shift, $+1-2νs$, while general strong head-tail instabilities give frequency with negative shift $νbeta-ν_s$. We study the synchro-beta spectrum using a code, PEHTS, which simulates single bunch electron cloud instability.  
 
FPAP005 Coupled Bunch Instability Caused by Electron Cloud simulation, feedback, betatron, positron 943
 
  • M. Tobiyama, J.W. Flanagan, H. Fukuma, S.-I. Kurokawa, K. Ohmi, S.S. Win
    KEK, Ibaraki
  Coupled bunch instability caused by electron cloud has been observed in some positron storage ring. We discuss the mode spectrum of the coupled bunch instability due to electrons moving in drift space, weak solenoid field and strong bending field. The mode spectrum of the instability is reflected by the electron motion: that is, we understand global characteristics of elecron motion from the mode spectrum.  
 
FPAP007 Measurement of the Electron Cloud Density Around the Beam simulation, positron, storage-ring, vacuum 1054
 
  • K.-I. Kanazawa, H. Fukuma, H. Hisamatsu, Y. Suetsugu
    KEK, Ibaraki
  Under the present operating condition of KEKB LER, most high energy electrons in the electron cloud that hit the chamber wall are produced near the circulating bunch by the single kick. By separating the high energy component of the electron current monitored at a pump port of a vacuum chamber, the density of the electron cloud near the beam is estimated. The estimated density is close to the order of magnitude expected from simulation. At present there still remains an ambiguity that comes from the detector efficiency in the measurement and the assumed secondary electron yield in the simulation.  
 
FPAP011 New Vortices in Axisymmetric Beams in Inhomogeneous Magnetic Field vacuum, plasma, cyclotron
 
  • Y. Golub
    MRTI RAS, Moscow
  We analyzed localized vortices in non-neutral inhomogeneous by density and velocity electron beams propagating in vacuum along the inhomogeneous external magnetic field. These vortices distinguish from vortices, which used in Golub Yu.Ya. et al. and Golub Yu.Ya. because of inhomogeneous external magnetic field. Also new types of vortex are obtained by new solution method of nonlinear equations.** The new method is development of a method described in Golub Yu.Ya. That method distinguish from standard Larichev-Reznik or Reznik method, which used in Golub Yu.Ya. et al. It has been found new expression for electric field potential of vortex in a wave frame. The expression is axisymmetric in a wave frame. New vortices are new solitons in the inhomogeneous external magnetic field.

*Golub Yu.Ya. et al., in Nonlinear world: IV Intern. Workshop on Nonlin. and Turbul. Proc. in Phys., (ed. by V.G. Bar'yakhtar et al.) World Scientific Publishing Co. Pte. Ltd., Singapore, 1990, vol. 2, p. 857. **Golub Yu.Ya., Proceedings of EPAC 2002, Paris, France, p. 1253.

 
 
FPAP012 The Effect of Inhomogeneous Magnetic Field on Budker-Chirikov Instability ion, resonance, simulation, betatron
 
  • Y. Golub
    MRTI RAS, Moscow
  The two-beams electron - ion system consists of a nonrelativistic ion beam propagating co-axially with a high-current relativistic electron beam in a longitudinal inhomogeneous magnetic field. The effect of the longitudinal inhomogeneous magnetic field on instability Budker-Chirikov (BCI) in the system is investigated by the method of a numerical simulation in terms of the kinetic description of both beams. The investigations are development of investigations in*,**. Is shown, when the inhomogeneity magnetic field results in the decreasing of an increment of instability Budker-Chirikov and the increasing of length of propagation of a electron beam. Also is shown, when take place the opposite result.

*Yu.Ya. Golub, N.E.Rozanov, Nuclear Instruments and Methods in Physics Research, A358 (1995) 479. **Yu.Ya. Golub, Proceedings of EPAC 2002, Paris, France, p. 1497.

 
 
FPAP013 Emittance Growth Caused by Electron Cloud Below the “Fast TMCI” Threshold: Numerical Noise or True Physics? emittance, simulation, proton, synchrotron 1344
 
  • E. Benedetto, E. Benedetto
    Politecnico di Torino, Torino
  • G. Franchetti
    GSI, Darmstadt
  • K. Ohmi
    KEK, Ibaraki
  • D. Schulte, F. Zimmermann
    CERN, Geneva
  Simulations show a persisting slow emittance growth for electron cloud densities below the threshold of the fast Transverse Mode Coupling type instability, which could prove important for proton beams with negligible radiation damping, such as in the LHC. We report on a variety of studies performed to quantify the contributions to the simulated emittance growth from numerical noise in the PIC module and from an artificial resonance excitation due to the finite number of kicks per turn applied for modeling the cloud-bunch interaction.  
 
FPAP014 Electron Cloud Measurements in the SPS in 2004 simulation, vacuum, proton, space-charge 1371
 
  • D. Schulte, G. Arduini, V. Baglin, J.M. Jimenez, F. Zimmermann
    CERN, Geneva
  Novel measurements of the electron cloud have been performed in the SPS in 2004. In this machine the beam consists of a number of short bunch trains. By varying the distance between these trains it is possible to witness the survival of the electrons after the bunch passage. In this paper, results from simulations and experiments are compared.  
 
FPAP016 Initial Self-Consistent 3-D Electron-Cloud Simulations of LHC Beam with the Code WARP+POSINST simulation, ion, proton, heavy-ion 1479
 
  • J.-L. Vay, M.A. Furman
    LBNL, Berkeley, California
  • R.H. Cohen, A. Friedman, D.P. Grote
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL and LBNL under contracts W-7405-Eng-48, and DE-AC03-76F00098.

We present initial results from the self-consistent beam-cloud dynamics simulations of a sample LHC beam, using a newly developed set of modeling capability based on a merger of the three-dimensional parallel Particle-In-Cell accelerator code WARP and the electron cloud code POSINST.*,** Although the storage ring model we use as a test bed to contain the beam is much simpler and shorter than the LHC, its lattice elements are realistically modeled, as is the beam and the electron cloud dynamics. The simulated mechanisms for generation and absorption of the electrons at the walls are based on previously validated models available in POSINST.***

*J.-L. Vay, these proceedings. **J.-L. Vay, Proc. "ECLOUD04," Napa (California), 2004. ***M.T.F. Pivi and M.A. Furman, Phys. Rev. STAB, PRSTAB/v6/i3/e034201.

 
 
FPAP017 Luminosity Optimization With Offset, Crossing Angle, and Distortion luminosity, positron, linear-collider, simulation 1541
 
  • J. Wu, T.O. Raubenheimer
    SLAC, Menlo Park, California
  Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.

In a linear collider, sources of beam jitter due to kicker noise, quadrupole vibration and long-range transverse wakefields will lead to beam offsets and tilts at the Intersection Point (IP). In addition, sources of emittance dilution such as short-range transverse wakefields or dispersive errors will lead to internal beam distortions. When the IP disruption parameter is large, these beam imperfections will be amplified by a single bunch kink instability which will lead to luminosity loss. In this paper, we study the luminosity loss and then the optimization required to cancel the luminosity loss first analytically and then with simulation.

 
 
FPAP018 Luminosity Loss Due to Beam Distortion and the Beam-Beam Instability luminosity, resonance, simulation, emittance 1586
 
  • J. Wu, A. Chao, T.O. Raubenheimer, A. Seryi
    SLAC, Menlo Park, California
  • C.K. Sramek
    Rice University, Houston, Texas
  Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.

In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ‘banana effect'). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particular, we examine the dependence of the luminosity loss on the wavelength of the beam distortions and the disruption parameter. This analysis may prove useful when optimizing the vertical disruption parameter for luminosity operation with given beam distortions.

 
 
FPAP020 Close-Coupling R-Matrix Approach to Simulating Ion-Atom Collisions for Accelerator Applications target, coupling, background, simulation 1685
 
  • P. Stoltz, A. Prideaux
    Tech-X, Boulder, Colorado
  Funding: Funded by DOE under grant # DE-FG02-02ER83553.

We have implemented an R-matrix close coupling approach to calculate capture, ionization, stripping and excitation cross-sections for 0.5 to 8.0 MeV K+ incident on Ar. This is relevant to the High Current Experiment at Lawrence Berkley National Laboratory. These cross sections are used to model accelerator particle dynamics where background gasses can interfere with beam quality. This code is a semi-classical approach that uses quantum mechanics to describe the particle interactions and uses classical mechanics to describe the nuclei trajectories. We compare a hydrogenic approximation for K+ with a pseudo-potential approach. Further we are developing a variational approach to quickly determine the best pseudo-potential parameters. Since many R-Matrix computationalists use this pseudo-potential approach, this approach will be useful for helping generate cross sections for any collision system.

 
 
FPAP021 A Cross-Platform Numerical Model of Ion-Wall Collisions ion, simulation, heavy-ion, vacuum 1707
 
  • S.A. Veitzer, P. Stoltz
    Tech-X, Boulder, Colorado
  • R.H. Cohen, A.W. Molvik
    LLNL, Livermore, California
  • J.-L. Vay
    LBNL, Berkeley, California
  Ion collisions with beam-pipe walls is a significant source of secondary electron clouds and desorbed neutral gasses in particle accelerators. Ions may reflect from beam-pipe walls and undergo further collisions downstream. These effects can cause beam degradation and are expected to be problematic in the design of heavy ion accelerators. The well-known SRIM code provides physically-based monte carlo simulations of ion-wall collisions. However, it is difficult to interface SRIM with high-performance simulation codes. We present details on the development of a package of Python modules which integrate the simulation of ion-wall interactions at grazing incidences with the high-performance particle-in-cell and electron cloud codes WARP and POSINST. This software package, called GriPY, calculates reflected angles and energies of ions which strike beam-pipe walls at grazing incidences, based upon interpolation of monte carlo statistics generated by benchmark simulations run in SRIM for a variety of relevant incident angles and energies. We present here solutions for 1.8 MeV K+ ions and 1 Gev protons incident on stainless steel.  
 
FPAP022 Long Time Simulation of LHC Beam Propagation in Electron Clouds space-charge, simulation, emittance, injection 1769
 
  • B. Feng, A.F. Ghalam, T.C. Katsouleas
    USC, Los Angeles, California
  • E. Benedetto, F. Zimmermann
    CERN, Geneva
  • V.K. Decyk, W.B. Mori
    UCLA, Los Angeles, California
  In this report we show the simulation results of single-bunch instabilities caused by interaction of a proton beam with an electron cloud for the Large Hadron Collider (LHC) using the code QuickPIC [1]. We describe three new results: 1) We test the effect of the space charge of the beam on itself; 2) we add the effect of dispersion in the equation of motion in the x direction, and 3) we extend previous modeling by an order of magnitude (from 50ms to 500ms) of beam circulation time. The effect of including space charge is to change the emittance growth by less than a few percent. Including dispersion changes the plane of instability but keeps the total emittance approximately the same. The longer runs indicate that the long term growth of electron cloud instability of the LHC beam cannot be obtained by extrapolating the results of short runs.  
 
FPAP024 Electron Cloud in the Collimator- and Injection- Region of the Spallation Neutron Source's Accumulator Ring beam-losses, injection, SNS, simulation 1865
 
  • L. Wang, H.-C. Hseuh, Y.Y. Lee, D. Raparia, J. Wei
    BNL, Upton, Long Island, New York
  • S.M. Cousineau, S. Henderson
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The beam loss along the Spallation Neutron Source’s (SNS’s) accumulator ring is mainly located at the collimator region. From the ORBIT simulation, the peak power deposition at the three collimators is about 500, 350 and 240 W/m, respectively. Therefore, a sizeable number of electrons may be accumulated at this region due to the great beam loss. This paper simulated the electron cloud at the collimator region and the possible remedy.

 
 
FPAP026 Multispecies Weibel Instability for Intense Ion Beam Propagation Through Background Plasma plasma, ion, background, heavy-ion 1952
 
  • R.C. Davidson, S.R. Hudson, I. Kaganovich, H. Qin, E. Startsev
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

In application of heavy ion beams to high energy density physics and fusion, background plasma is utilized to neutralize the beam space charge during drift compression and/or final focus of the ion beam. It is important to minimize the deleterious effects of collective instabilities on beam quality associated with beam-plasma interactions. Plasma electrons tend to neutralize both the space charge and current of the beam ions. It is shown that the presence of the return current greatly modifies the electromagnetic Weibel instability (also called the filamentation instability), i.e., the growth rate of the filamentation instability greatly increases if the background ions are much lighter than the beam ions and the plasma density is comparable to the ion beam density. This may preclude using underdense plasma of light gases in heavy ion beam applications. It is also shown that the return current may be subject to the fast electrostatic two-stream instability.

 
 
FPAP027 Hybrid Quantum Mechanical–Quasi-Classical Model for Evaluating Ionization and Stripping Cross Sections in Atom-Ion Collisions ion, target, heavy-ion, plasma 1988
 
  • I. Kaganovich, R.C. Davidson, E. Startsev
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

Ion-atom ionization cross sections are needed in many applications employing the propagation of fast ions through matter. When experimental data or full-scale theoretical calculations are non-existent, approximate methods must be used. The most robust and easy-to-use approximations include the Born approximation of quantum mechanics and the quasi-classical approach utilizing classical mechanics together with the Bohr-Sommerfeld quantization rule.* The simplest method to extend the validity of both approaches is to combine them, i.e., use the two different approaches but only for the regions of impact parameters in which they are valid, and sum the results to obtain the total cross section. We have recently investigated theoretically and experimentally the stripping of more than 18 different pairs of projectile and target atoms in the range of 3-38 MeV/amu to study the range of validity of various approximations. The results of the modified approach agree better with the experimental data than either the Born approximation or the quasi-classical approach, applied separately.

*I. D. Kaganovich et al., "Formulary and scaling cross sections for ion-atom impact ionization," http://arxiv.org/abs/physics/0407140.

 
 
FPAP028 Ion Beam Pulse Interaction with Background Plasma in a Solenoidal Magnetic Field ion, plasma, background, target 2062
 
  • I. Kaganovich, R.C. Davidson, E. Startsev
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

Background plasma can be used as an effective neutralization scheme to transport and compress intense ion beam pulses, and the application of a solenoidal magnetic field allows additional control and focusing of the beam pulse. Ion beam pulse propagation in a background plasma immersed in an applied solenoidal magnetic field has been studied both analytically and numerically with three different particle-in-cell codes (LSP, OOPIC-Pro and EDPIC) to cross-check the validity of the results. Very good charge and current neutralization is observed for high values of the solenoidal magnetic field.* However, for intermediate values of the solenoidal magnetic field, current neutralization is a complex process, and a sizable self-magnetic field is generated at the head of the beam. Collective wave excitations are also generated ahead of the beam pulse.

*I. D. Kaganovich, E. A. Startsev and R. C. Davidson, Nuclear Instruments and Methods in Physics Research A, in press (2004).

 
 
FPAP031 Model of Electron Cloud Build Up with Secondary Ion-Electron Emission as a Source of Delayed Electrons ion, vacuum, proton, space-charge 2197
 
  • V.G. Dudnikov, G. Dudnikova
    BTG, New York
  For explanation of anomaly long electron cloud surviving after the gap between bunches it was proposed beam particle leaking to the gap and anomaly high reflectivity of low energy electrons in collision with pipe wall. We will attract an attention to some other possibilities of efficient electron generation in the high vacuum environment and delay electron generation after gap between bunches. Model of electron cloud build up with secondary ion-electron emission as a source of delay electrons is presented and discussed. This model is used for explanation of bunched beam instability in Los Alamos PSR, prediction of e-cloud generation in SNS, and can be important for pressure rise in cold sections of RHIC. A fast desorbtion by ion of physically adsorbed molecules can explain a "first pulse Instability" observed in LA PSR  
 
FPAP033 Beam Energy Scaling of Ion-Induced Electron Yield from K+ Ions Impact on Stainless Steel Surfaces ion, target, heavy-ion, diagnostics 2287
 
  • M. Kireeff Covo, J.J. Barnard, R.H. Cohen, A. Friedman, D.P. Grote, S.M. Lund, A.W. Molvik, G.A. Westenskow
    LLNL, Livermore, California
  • D. Baca, F.M. Bieniosek, C.M. Celata, J.W. Kwan, P.A. Seidl, J.-L. Vay
    LBNL, Berkeley, California
  • J.L. Vujic
    UCB, Berkeley, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL under contract No. W-7405-Eng-48, and by LBNL under Contract DE-AC03-76F00098.

The cost of accelerators for heavy-ion inertial fusion energy (HIF) can be reduced by using the smallest possible clearance between the beam and the wall from the beamline. This increases beam loss to the walls, generating ion-induced electrons that could be trapped by beam space charge potential into an "electron cloud," which can cause degradation or loss of the ion beam. In order to understand the physical mechanism of production of ion-induced electrons we have measured impact of K+ ions with energies up to 400 KeV on stainless steel surfaces near grazing incidence, using the ion source test stand (STS-500) at LLNL. The electron yield will be discussed and compared with experimental measurements from 1 MeV K+ ions in the High-Current Experiment at LBNL.*

*A.W. Molvik et al., PRST-AB 7, 093202 (2004).

 
 
FPAT025 Electron Dynamics of the Rod-Pinch Diode in the Cygnus Experiment at Los Alamos cathode, simulation, ion, plasma 1901
 
  • L. Yin, K. J. Bowers, R.C. Carlson, BG.D. DeVolder, J. T. Kwan, JR.S. Smith, CM.S. Snell
    LANL, Los Alamos, New Mexico
  • MJ.B. Berninger
    Bechtel Nevada, Los Alamos, New Mexico
  In this work, two-dimensional particle-in-cell simulations are used to examine the electron physics in the rod-pinch diode, a device that can be used to produce a relatively low-energy (a few MeV) radiographic electron source. It is found that with diode parameters for which the electrons' dominant dynamics are approximated well as a magnetized fluid, the diode produces an electron source with a desired small spot size as the electrons drift to and impinge on the anode tip. However, for a large cathode-to-anode radius ratio, a population of electrons that consists predominantly of electrons emitted from the downstream surface of the cathode is found to propagate in the upstream direction and the diode may perform anomalously as a consequence. A method is proposed for improving the quality of the electron source by suppressing electron emission from the downstream cathode surface to reduce the presence of unmagnetized electrons.  
 
FPAT033 Numerical Model of the DARHT Accelerating Cell simulation, pulsed-power 2269
 
  • T.P. Hughes, T.C. Genoni
    ATK-MR, Albuquerque, New Mexico
  • H. Davis, M. Kang, B.A. Prichard
    LANL, Los Alamos, New Mexico
  Funding: NNSA/DOE

The DARHT-2 facility at Los Alamos National Laboratory accelerates a 2 microsecond electron beam using a series of inductive accelerating cells. The cell inductance is provided by large Metglas cores, which are driven by a pulse-forming network. The original cell design was susceptible to electrical breakdown near the outer radius of the cores. We developed a numerical model for the magnetic properties of Metglas over the range of dB/dt (magnetization rate) relevant to DARHT. The model was implemented in a radially-resolved circuit code, and in the LSP* electromagnetic code. LSP simulations showed that the field stress distribution across the outer radius of the cores was highly nonuniform. This was subsequently confirmed in experiments at LBNL. The calculated temporal evolution of the electric field stress inside the cores approximately matches experimental measurements. The cells have been redesigned to greatly reduce the field stresses along the outer radius.

*LSP is a software product of ATK Mission Research (www.lspsuite.net).

 
 
FPAT036 An Induction Linac Test Stand induction, pulsed-power, linac, diagnostics 2455
 
  • W. J. DeHope, D.A. Goerz, R. Kihara, M.M. Ong, G.E. Vogtlin, J.M. Zentler
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. 7405-Eng-48.

A single-cell test stand has been constructed to facilitate study and guide improvements of the induction electron linac at the FXR radiographic facility at LLNL.* This paper will discuss how modifications in pulse compression and shaping, pulse power transmission, initial ferrite state, and accelerator cell loading have been performed on the test stand and can be applied to the entire accelerator. Some of the specialized diagnostics being used will be described. Finally, the paper will discuss how computer modeling and judicious timing control can be used to optimize accelerator performance by making only selective changes that can be accomplished at minimal cost.

*"Test Stand for Linear Induction Accelerator Optimization," Ong et al., Pulsed Power Conference, June 16, 2003, Dallas TX.

 
 
FPAT046 RF Control System for the DESY VUV-FEL Linac feedback, diagnostics, linac, klystron 2899
 
  • V. Ayvazyan, G.M. Petrosyan, K. Rehlich, S. Simrock, P. Vetrov
    DESY, Hamburg
  In the RF system for the Vacuum Ultraviolet Free Electron Laser (VUV-FEL) Linac each klystron supplies RF power to up to 32 cavities. The superconducting cavities are operated in pulsed mode and high accelerating gradients close to the performance limit. The RF control of the cavity fields to the level of 1·10-4 for amplitude and 0.1 degree for phase however presents a significant technical challenge due to the narrow bandwidth of the cavities which results in high sensitivity to perturbations of the resonance frequency by mechanical vibrations (microphonics) and Lorentz force detuning. A digital RF control system has been developed for the VUV-FEL which will demonstrate the required control performance. Presently the Linac is being commissioned, and this effort provides the first full integrated test in the accelerator, including cryogenics, RF, beam transport, and beam diagnostics. The RF control system design and objectives are discussed and compared to the measured performance during the first stage of the VUV-FEL Linac - TESLA Test Facility. Hardware/software design and operational challenges experienced for RF control are presented.  
 
FPAT051 A New Timing System for the Duke Booster and Storage Ring booster, injection, linac, storage-ring 3159
 
  • G.Y. Kurkin
    BINP SB RAS, Novosibirsk
  • S.M. Hartman, S. Mikhailov, Y.K. Wu
    DU/FEL, Durham, North Carolina
  • I.P. Pinayev
    BNL, Upton, Long Island, New York
  Funding: AFOSR MFEL grant number is F49620-001-0370, HIGS Upgrade DOE grant number is DE-FG02-01ER41175.

A dedicated booster synchrotron is being constructed at the Duke FEL Laboratory to provide full energy injection into the main electron storage ring. A new timing system has been developed to coordinate the injection of electron bunches from the linac to the booster, the ramping of energy in the booster, and extraction of bunches into the main ring. The timing system will allow the extraction of any bunch in the booster into any selected bucket in the main ring to provide top-off injection for any of the various operational bunch patterns of the main ring. A new master oscillator has also been developed for the RF system of the booster. The oscillator may be tuned independently or phase-locked to the master oscillator of the main ring. The issues of the soft phase locking process of the new master oscillator are discussed. The timing system and new oscillator have been fabricated and tested and are ready for operation.

 
 
FPAT061 CEBAF Distributed Data Acquisition System linac, beam-losses, klystron, controls 3541
 
  • T.L. Allison, T. Powers
    Jefferson Lab, Newport News, Virginia
  Funding: This work was supported by DOE contract DE-AC05-84ER40150 Modification No. M175, under which the Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility.

There are thousands of signals distributed throughout Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) that are useful for troubleshooting and identifying instabilities. Many of these signals are only available locally or monitored by systems with small bandwidths that cannot identify fast transients. The Distributed Data Acquisition (Dist DAQ) system will sample and record these signals simultaneously at rates up to 40 Msps. Its primary function will be to provide waveform records from signals throughout CEBAF to the Experimental Physics and Industrial Control System (EPICS). The waveforms will be collected after the occurrence of an event trigger. These triggers will be derived from signals such as periodic timers or accelerator faults. The waveform data can then be processed to quickly identify beam transport issues, thus reducing down time and increasing CEBAF performance. The Dist DAQ system will be comprised of multiple standalone chassis distributed throughout CEBAF. They will be interconnected via a fiber optic network to facilitate the global triggering of events. All of the chassis will also be connected directly to the CEBAF Ethernet and run EPICS locally. This allows for more flexibility than the typical configuration of a single board computer and other custom printed circuit boards (PCB) installed in a card cage.

allison@jlab.org

 
 
FPAT082 From Visualisation to Data Mining with Large Data Sets simulation, proton, synchrotron, synchrotron-radiation 4114
 
  • A. Adelmann
    PSI, Villigen
  • R.D. Ryne, J.M. Shalf, C. Siegerist
    LBNL, Berkeley, California
  In 3D particle simulations, the generated 6D phase space data are can be very large due to the need for accurate statistics, sufficient noise attenuation in the field solver and tracking of many turns in ring machines or accelerators. There is a need for distributed applications that allow users to peruse these extremely large remotely located datasets with the same ease as locally downloaded data. This paper will show concepts and a prototype tool to extract useful physical information out of 6D raw phase space data. ParViT allows the user to project 6D data into 3D space by selecting which dimensions will be represented spatially and which dimensions are represented as particle attributes, and the construction of complex transfer functions for representing the particle attributes. It also allows management of time-series data. An HDF5-based parallel-I/O library, with C++, C and Fortran bindings simplifies the interface with a variety of codes. A number of hooks in ParVit will allow it to connect with a parallel back-end that is able to provide remote file access, progressive streaming, and even parallel rendering of particle sets in excess of 1Billion particles.  
 
FPAT086 Lucretia: A Matlab-Based Toolbox for the Modeling and Simulation of Single-Pass Electron Beam Transport Systems simulation, lattice, linac, klystron 4197
 
  • P. Tenenbaum
    SLAC, Menlo Park, California
  We report on Lucretia, a new simulation tool for the study of single-pass electron beam transport systems. Lucretia supports a combination of analytic and tracking techniques to model the tuning and operation of bunch compressors, linear accelerators, and beam delivery systems of linear colliders and linac-driven Free Electron Laser (FEL) facilities. Extensive use of Matlab scripting, graphics, and numerical capabilities maximize the flexibility of the system, and emphasis has been placed on representing and preserving the fixed relationships between elements (common girders, power supplies, etc.) which must be respected in the design of tuning algorithms. An overview of the code organization, some simple examples, and plans for future development are discussed.  
 
FPAT091 LiTrack: A Fast Longitudinal Phase Space Tracking Code with Graphical User Interface linac, focusing, acceleration, RF-structure 4266
 
  • P. Emma, K.L.F. Bane
    SLAC, Menlo Park, California
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

Many linear accelerators, such as linac-based light sources and linear colliders, apply longitudinal phase space manipulations in their design, including electron bunch compression and wakefield-induced energy spread control. Several computer codes handle such issues, but most require detailed information on the transverse focusing lattice. In fact, in most linear accelerators, the transverse distributions do not significantly affect the longitudinal, and can be ignored initially. This allows the use of a fast 2D code to study longitudinal aspects without time-consuming considerations of the transverse focusing. LiTrack is based on a 15-year old code (same name) originally written by one of us (KB), which is now a MATLAB-based code with additional features, such as a graphical user interface and output plotting. The single-bunch tracking includes RF acceleration, bunch compression to 3rd order, geometric and resistive wakefields, aperture limits, synchrotron radiation, and flexible output plotting. The code was used to design both the LCLS and the SPPS projects at SLAC and typically runs in <1 minute. We describe the features, show some examples, and provide access to the code.

 
 
FOAA002 Technological Improvements in the DARHT II Accelerator Cells vacuum, cathode, induction, linac 169
 
  • B.A. Prichard, R.J. Briggs
    SAIC, Los Alamos, New Mexico
  • J. Barraza, M. Kang, K. Nielsen
    LANL, Los Alamos, New Mexico
  • F.M. Bieniosek, K. Chow, W.M. Fawley, E. Henestroza, L. R. Reginato, W. Waldron
    LBNL, Berkeley, California
  • T.E. Genoni, T.P. Hughes
    ATK-MR, Albuquerque, New Mexico
  Funding: This work was supported by the U.S. National Nuclear Security Agency and the U.S. Department of Energy under contract W-7405-ENG-36.

DARHT employs two perpendicular electron Linear Induction Accelerators to produce intense, bremsstrahlung x-ray pulses for flash radiography. The second axis, DARHT II, features an 18 MeV, 2-kA, 2-microsecond accelerator. DARHT II accelerator cells have undergone a series of test and modeling efforts to fully understand their sub par performance. These R&D efforts have led to a better understanding of Linear Induction Accelerator physics for the unique DARHT II design. Specific improvements have been identified and tested. Improvements in the cell oil region, the cell vacuum region, and the PFNs have been implemented in the prototype units that have doubled the cell’s performance. A series of prototype acceptance test are underway on a number of prototype units to demonstrate that the required cell lifetime is met at the improved performance levels. Early acceptance tests indicate that the lifetime requirements are being exceeded. The shortcomings of the previous design are summarized. The improvements to the original design, their resultant improvement in performance, and various test results are included. The final acceptance test results will also be included.

 
 
FOAA008 Superconducting RF Development at Nuclear Science Centre linac, vacuum, ion, coupling 625
 
  • A. Roy
    NSC, New Delhi
  Funding: Nuclear Science Centre, New Delhi, India.

A Superconducting Linac is being installed as a booster for the 15 UD Pelletron accelerator at Nuclear Science Centre (NSC). The accelerating structure for this linac is a Nb QWR cavity, designed and fabricated as a joint collaboration between NSC and ANL, USA. Initial cavities required for the first linac module were fabricated at ANL. For fabrication of cavities required for future modules a Superconducting Resonator Fabrication Facility has been set up at NSC. Three quarter wave resonator (QWR) cavities have been fabricated using the in-house facility. This facility has been used for repairs on the resonators which sprung leaks. Fabrication of fifteen resonators for the second and third linac modules is under progress. Eight resonators along with a superconducting solenoid has been installed in the first linac cryostat and tested for energy gain with a pulsed beam of 90 MeV Si from the Pelletron. Acceleration of the ions to 96 MeV was measured downstream and beam transmission through the linac was measured to be ~ 100%.

 
 
FOAB001 Compact Neutron Generators for Medical, Home Land Security, and Planetary Exploration ion, ion-source, plasma, target 49
 
  • J.P. Reijonen
    LBNL, Berkeley, California
  Funding: This work is being support by U.S. Department of Energy under contract No. DE-AC03-76SF00098.

The Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory has developed various types of advanced D-D (neutron energy 2.5 MeV), D-T (14 MeV) and T-T (0 – 9 MeV) neutron generators for wide range of applications. These applications include medical (Boron Neutron Capture Therapy), homeland security (Prompt Gamma Activation Analysis, Fast Neutron Activation Analysis and Pulsed Fast Neutron Transmission Spectroscopy) and planetary exploration in form of neutron based, sub-surface hydrogen detection systems. These neutron generators utilize RF induction discharge to ionize the deuterium/tritium gas. This discharge method provides high plasma density for high output current, high atomic species from molecular gases, long life operation and versatility for various discharge chamber geometries. Three main neutron generator developments are discussed here: high neutron output co-axial neutron generator for BNCT applications, point neutron generator for security applications, compact and sub-compact axial neutron generator for elemental analysis applications. Current status of the neutron generator development with experimental data will be presented.

 
 
FOAB002 Advances in X-Band and S-Band Linear Accelerators for Security, NDT, and Other Applications linac, radiation, gun, vacuum 240
 
  • A.V. Mishin
    AS&E, Billerica, Massachusetts
  At AS&E High Energy Systems Division, we designed several new advanced high energy electron beam and X-ray sources. Our primary focus has always been in building the world’s most portable commercial X-band accelerators. Today, our X-band systems frequently exceed performance of the similar S-band machines, while they are more portable compared to the latter. The new designs of the X-band accelerators in the most practical energy range from 1 MeV to 6 MeV have been tested delivering outstanding results. Seventy 6 MeV X-band linacs systems have been produced. The most compact linac for security is used by AS&E in a self-shielded, Shaped Energy™ cargo screening system. We pioneered using the X-band linear accelerators for CT, producing high quality images of oil pipes and wood logs. An X-band linear accelerator head on a robotic arm has been used for electron beam radiation curing of an odd-shaped graphite composite part. We developed the broad-range 4 MeV to over 10 MeV energy-regulated X-band and S-band systems for medical and NDT applications. The regulated pulse length systems operating in a range from nanoseconds to microseconds have been built both in X-band and in S-band frequency range.  
 
FOAB005 Technology for Fissionable Materials Detection by Use of 100 MeV Variable Linac photon, linac, background, simulation 446
 
  • S.P. Karasyov, A.N. Dovbnja, L. Eran, Y.P. Melnik, Y. Ran'iuk, I.N. Shlyakhov
    NSC/KIPT, Kharkov
  • A.J. Baratta
    Penn State University, University Park, Pennsylvania
  • N.M. Kiryukhin
    ATSU, Kiev
  • S.V. Trubnikov
    KhNU, Kharkov
  Funding: This project is funded by CRDF FSTM UKE2-5023-KH-04.

A new concept for a two-step facility to increase the accuracy/reliability of detecting heavily shielded fissionable materials (FM) in marine containers is presented. The facility will detect FM in two steps. An existing dual-view; dual-energy X-ray scanner, which is based on 7 MeV electron accelerator, will select the suspicious places inside container. The linac with variable energy (up to 100 MeV) will be used for the second step. The technology will detect fissionable nuclei by gamma induced fission reactions and delayed neutron registration. A little-known Ukrainian experimental data obtained in Chernobil’ clean-up program will be presented to ground proposed concept. The theoretical calculations of neutron fluxes scale these results to marine container size. Modified GEANT code for electron/gamma penetration and authors’ own software for neutron yield/penetration are used for these calculations. Available facilities (X-ray scanners; linac; detectors), which will be used for concept proof, are described. The results of the first experiments by use variable energy linac are cited.

 
 
FOAB010 Present Status of Photo-Cathode RF Gun System and Its Applications laser, injection, gun, emittance 710
 
  • R. Kuroda, Y. Hama, K. Hidume, M. Kawaguchi, R. Moriyama, T. Saito, K. Sakaue, M. Washio
    RISE, Tokyo
  • H. Hayano, J.U. Urakawa
    KEK, Ibaraki
  • S. Kashiwagi
    ISIR, Osaka
  High quality electron beam generation using photo-cathode rf gun system and its applications have been developed at Waseda University. This system can generate up to 4.6 MeV low emittance electron beam. It is applied for soft X-ray generation using laser Compton scattering and pulse radiolysis experiments based on the pump-probe technique. In the former, Compton scattering experiments between about 4.6 MeV electron beam and 1047 nm laser beam is performed at 20 degrees interaction angle, so that about 370 eV soft X-ray is generated. In the latter, the electron beam is used for the pump beam and the probe beam is generated as white light by concentrating laser beam on the water cell, so that the measurement with about 30 ps (FWHM) time resolution of the pulse radiolysis system is demonstrated for the absorption of hydrated electrons. In this conference, we will present the experimental results, status of this system and future applications.  
 
FOAD002 Ultra-High Density Electron Beams for Beam Radiation and Beam Plasma Interaction emittance, focusing, simulation, plasma 145
 
  • S.G. Anderson, J. Brown, D.J. Gibson, F.V. Hartemann, J.S. Jacob, A.M. Tremaine
    LLNL, Livermore, California
  • P. Frigola, J. Lim, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • P. Musumeci
    INFN-Roma, Roma
  Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.

Current and future applications of high brightness electron beams, which include advanced accelerators such as the plasma wake-field accelerator (PWFA) and beam-radiation interactions such as inverse-Compton scattering (ICS), require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at LLNL’s PLEIADES ICS x-ray source in which the photoinjector-generated beam has been compressed to 300 fsec duration using the velocity bunching technique and focused to 20 μm rms size using an extremely high gradient, permanent magnet quadrupole (PMQ) focusing system.

 
 
FOAD004 Laser Cooling of Relativistic Heavy Ion Beams ion, laser, synchrotron, heavy-ion 401
 
  • U. Schramm, M.H. Bussmann, D. Habs
    LMU, München
  • K. Beckert, P. Beller, B.  Franzke, T. Kuehl, F. Nolden, M. Steck
    GSI, Darmstadt
  • S. Karpuk
    Johannes Gutenberg University Mainz, Mainz
  • S. Reinhardt, G. Saathoff
    MPI-K, Heidelberg
  Funding: Partially funded by the german BMBF (06ML183).

We report on the first laser cooling of a bunched beam of multiply charged C3+ ions performed at the ESR (GSI) at a beam energy of E=1.47GeV. Moderate bunching provided a force counteracting the decelerating laser force of one counterpropagating UV laser beam. This versatile type of laser cooling lead to longitudinally space-charge dominated beams with an unprecedented relative momentum spread of 10-7. Concerning the beam energy and charge state of the ion, the experiment depicts an important intermediate step from the established field of laser cooling of ion beams at low energies toward the laser cooling scheme proposed for relativistic beams of highly charged heavy ions at the future GSI facility FAIR.