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Paper Title Other Keywords Page
MPPE012 MAD-X PTC Integration lattice, optics, synchrotron, synchrotron-radiation 1272
  • F. Schmidt
    CERN, Geneva
  MAD-X is CERN's successor for MAD8, a program for accelerator design with a long history. MAD-X is a modular, better maintainable re-write of MAD8 with data structures written in C. Early on in the design of MAD-X we relied on the fact that older or doubtful modules could be replaced by new modules using the PTC code by E. Forest. Both codes remain independent entities but are linked via a converter to the MAD-X data structures. PTC is used for symplectic tracking of smaller machines and transfer line using better defined physical models of the elements and taking into account of how the elements are placed in the tunnel. The matching of the LHC will profit form the fact that the high order nonlinear parameters are provided by a PTC Normal Form analysis.  
MPPE020 Control of Dynamic Aperture for Synchrotron Light Sources optics, sextupole, emittance, lattice 1670
  • J. Bengtsson
    BNL, Upton, Long Island, New York
  Funding: Under Contract with the U.S. Department of Energy Contract Number DE-AC02-98CH10886.

Given the following frameworks: "A Hamiltonian-Free Description of Single Particle Dynamics for Hopelessly Complex Periodic Systems" (Forest, 1990), "Normal Form Methods for Complicated Periodic Systems" (Forest, Berz, Irwin, 1989), "The Correct Local Description for Tracking in Rings" (Forest, 1994), "The C++ Programming Language" (Stroustrup, 1985), we have designed a compact object oriented beam dynamics class by re-using existing FORTRAN libraries for: Truncated Power Series Algebra (Berz, SSC, 1988), and Map Normal Rorm (Forest, CBP, LBNL, 1990). In other words, implemented a numerical- and analytical model for: 6-dim phase space tracking, with classical radiation, and evaluation of equilibrium emittance, driving terms, amplitude dependent tune shifts, chromaticity, momentum compaction, etc., to arbitrary order, with self-consistent treatment of magnet errors. The tool was developed for the lattice design of NSLS-II.

MPPE073 Effects of the Passive Harmonic Cavity on the Beam Bunch synchrotron, beam-loading, impedance, electron 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.  
MPPT020 Magnetic Field Measurement on a Refined Kicker kicker, injection, storage-ring, synchrotron 1682
  • T.-C. Fan, C.-S. Hwang, F.-Y. Lin
    NSRRC, Hsinchu
  To prepare for the operation of top-up mode and increase the efficiency of injection at storage ring, National Synchrotron Radiation Research Center (NSRRC) has upgraded the kicker magnets and power supply. We have built up a new magnetic field measurement system to test the kicker. This system, including a search coil and a coil loop, can map the field and take the first integral of field automatically. We also simulate the trajectory of electron beam by pulsed wire method of field measurement. We analyze the performance of the kicker system in this paper.  
MPPT031 Radiation Resistant Magnets for the RIA Fragment Separator target, quadrupole, dipole, sextupole 2200
  • A. Zeller, V. Blideanu, R.M. Ronningen, B. Sherrill
    NSCL, East Lansing, Michigan
  • R.C. Gupta
    BNL, Upton, Long Island, New York
  Funding: Supported in part by Michigan State University and the U.S. DOE.

The high radiation fields around the production target and the beam dump in the fragment separator at the Rare Isotope Accelerator requires that radiation resistant magnets be used. Because large apertures and high gradients are required for the quadrupoles and similar demanding requirements for the dipole and sextupoles, resistive coils are difficult to justify. The radiation heating of any materials at liquid helium temperatures also requires that superconducting versions of the magnets have low cold-masses. The final optical design has taken the practical magnets limits into account and sizes and fields adjusted to what is believed to be achievable with technology that is possible with sufficient R&D. Designs with higher obtainable current densities and having good radiation tolerances that use superconducting coils are presented, as well as the radiation transport calculations that drive the material parameters.

MPPT032 Construction and Performance of Superconducting Magnets for Synchrotron Radiation electron, wiggler, 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.  
MPPT048 Test Results of HTS Coil and Magnet R&D for RIA quadrupole, dipole, superconductivity, superconducting-magnet 3016
  • R.C. Gupta, M. Anerella, M. Harrison, W. Sampson, J. Schmalzle
    BNL, Upton, Long Island, New York
  • A. Zeller
    NSCL, East Lansing, Michigan
  Funding: Work supported by the U.S. Department of Energy and by the National Science Foundation.

Brookhaven National Laboratory is developing quadrupole magnets for the proposed Rare Isotope Accelerator (RIA) based on commercially available High Temperature Superconductors (HTS). These quadrupoles will be used in the Fragment Separator region and are one of the more challenging elements in the RIA proposal. They will be subjected to several orders of magnitude more energy and radiation deposition than typical beam line and accelerator magnets receive during their entire lifetime. The proposed quadrupoles will operate in the 20-40 K temperature range for efficient heat removal. HTS coils that have been tested so far indicate that the coils meet the magnetic field requirements of the design. We will report the test results of about 10 HTS coils and of a magnetic mirror configuration that simulates the magnetic field and Lorentz force in the proposed quadrupole. In addition, the preliminary design of an HTS dipole magnet for the Fragment Separator region will also be presented.

MPPT049 Optimization of Open Midplane Dipole Design for LHC IR Upgrade dipole, luminosity, optics, quadrupole 3055
  • R.C. Gupta, M. Anerella, A. Ghosh, M. Harrison, J. Schmalzle, P. Wanderer
    BNL, Upton, Long Island, New York
  • N.V. Mokhov
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886.

The proposed ten-fold increase in Large Hadron Collider (LHC) luminosity requires high field (~15 T) magnets that are subjected to the high radiation power of ~9 kW/per beam directed towards each interaction region. This has a major impact in the design of first dipole in the "Dipole First" optics. The proposed design allows sufficient clear space between coils so that most of the particle showers from the interaction points (concentrated at the midplane due to strong magnetic field) can be transported outside the coil region to a warm absorber thus drastically reducing the peak power density in the coils and removing heat at a higher (nitrogen) temperature. The concept, however, presents several new technical challenges: (a) obtaining good field quality despite a large midplane gap, (b) minimizing peak fields on coil, (c) dealing with large vertical forces with no structure between the coils, (d) minimizing heat deposition in the cold region, (e) designing a support structure. Designs with different horizontal and vertical coil spacing are presented that offer significant savings in the operating and infrastructure cost of the cryo-system, providing reliable quench-stable operation with a lifetime of the critical components of at least ten years.

MPPT075 Analysis and Design of Backing Beam for Multipole Wiggler (MPW14) at PLS multipole, wiggler, synchrotron, synchrotron-radiation 3940
  • H.-G. Lee, C.W. Chung, H.S. Han, Y.G. Jung, D.E. Kim, W.W. Lee, K.-H. Park, H.S. Suh
    PAL, Pohang, Kyungbuk
  Pohang Accelerator Laboratory (PAL) had developed and installed a Multipole Wiggler (MPW14) to utilize high energy synchrotron radiation at Pohang Light Source (PLS). The MPW14 is a hybrid type device with period of 14 cm, minimum gap of 14 mm, maximum flux density of 2.02 Tesla and total magnetic structure length of 2056 mm. The support locations and structure of an insertion device are optimized to achieve a minimum deflection due to the magnetic loads. A Finite Element Analysis (FEA) is performed to find out the amount of maximum deflection and optimal support positions on the backing beam, the support and drive structures of the MPW14 under expected magnetic load of 14 tons. To reduce the deflection effect further, two springs are designed and installed to compensate the gap dependent magnetic loads. The optimized deflection is estimated to be about 20.6 ? while the deflection before optimization is 238 ?.  
MPPT077 Radiation of Electron in the Field of Plane Light Wave electron, 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.  
MPPT083 Radiation Damage to Advanced Photon Source Undulators undulator, electron, 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).

MPPT091 Managing Coil Epoxy Vacuum Impregnation Systems at the Manufacturing Floor Level To Achieve Ultimate Properties in State-of-the-Art Magnet Assemblies vacuum, monitoring, insertion, induction 4260
  • J.G. Hubrig
    Innovation Services, Inc, Knoxville, Tennessee
  • G.H. Biallas
    Jefferson Lab, Newport News, Virginia
  Liquid epoxy resin impregnation systems remain a state-of-the-art polymer material for vacuum and vacuum/pressure impregnation applications in the manufacture of both advanced and conventional coil winding configurations. Epoxy resins inherent latitude in processing parameters accounts for their continued popularity in engineering applications, but also for the tendency to overlook or misinterpret the requisite processing parameters on the manufacturing floor. Resin system impregnation must be managed in detail in order to achieve device life cycle reliability. This closer look reveals how manufacturing floor level management of material acceptance, handling and storage, pre- and post- impregnation processing and cure can be built into a manufacturing plan to increase manufacturing yield, lower unit cost and ensure optimum life cycle performance of the coil.  
MOPB010 Simulations and Experiments of Electron Beams Pre-Modulated at the Photocathode electron, simulation, laser, 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.

TOAC005 Coherent Synchrotron Radiation as a Diagnostic Tool for the LCLS Longitudinal Feedback System feedback, electron, 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, electron 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.  
TPAE010 Resonant Excitation of Selected Modes by a Train of Electron Bunches in a Rectangular Dielectric Wakefield Accelerator electron, single-bunch, 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, acceleration, focusing, electron 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.  
TPAE013 Rectangular Dielectric-Lined Two-Beam Wakefield Accelerator Structure acceleration, vacuum, extraction, coupling 1333
  • C. Wang, V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  • T.C. Marshall
    Columbia University, New York
  Funding: Work supported by U.S. DOE.

A novel dielectric structure is described for a two-beam wake field accelerator (WFA), which consists of three or four rectangular dielectric slabs positioned within a rectangular conducting pipe. This structure can be thought of as equivalent to two symmetric dielectric-lined three-zone rectangular waveguides, joined side-by-side. The design mode in the two-beam structure is the LSM-31 mode, a combination of two symmetric LSM-11 modes of the two three-zone waveguides. This two-channel mode can be employed to decelerate drive particles in one channel and accelerate test particles in the other. It is possible to find structure parameters that give a high ratio of acceleration gradient for the test beam, to deceleration gradient for the drive beam, of the order of 100.

TPAE015 Laser and Particle Guiding Micro-Elements for Particle Accelerators laser, undulator, vacuum, focusing 1434
  • T. Plettner, R.M. Gaume, J. Wisdom
    Stanford University, Stanford, Califormia
  • J.E. Spencer
    SLAC, Menlo Park, California
  Funding: Department of Energy contract DE-AC02-76SF00515, DARPA contract DAAD19-02-1-0184.

Laser driven particle accelerators based on the current generation of lasers will require sub-micron control of the laser field as well as precise beam guiding. Hence the fabrication techniques that allow integrating both elements into an accelerator-on-chip format become critical for the success of such particle accelerators. Micromachining technology for silicon has been shown to be one such feasible technology in PAC2003 but with a variety of complications on the laser side. Fortunately, in recent years the fabrication of transparent ceramics has become an interesting technology that could be applied for laser-particle accelerators in several ways. We discuss this area, its advantages such as the range of materials it provides and various ways to implement it followed by some different test examples that have been considered. One important goal of this approach is an integrated system that could avoid the necessity of having to inject either laser or particle pulses into these structures.

TPAE024 Determination of Longitudinal Phase Space in SLAC Main Accelerator Beams simulation, plasma, electron, acceleration 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, electron, acceleration, diagnostics 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 electron, 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.

TPAE030 Distributed Bragg Coupler for Optical All-Dielectric Electron Accelerator coupling, laser, electron, vacuum 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.

TPAE033 Experimental and Numerical Studies of Particle Acceleration by an Active Microwave Medium laser, acceleration, simulation, resonance 2275
  • P. Schoessow
    Tech-X, Boulder, Colorado
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  There has been considerable theoretical work on the so-called PASER concept, in which a particle beam is accelerated directly by absorbing energy from an active medium, analogous to the amplification of an optical signal in a laser. Use of an active microwave (maser) medium would have the advantage of requiring relaxed beam quality (mm vs. nm characteristic beam dimensions). Recent work using electron paramagnetic resonance (EPR) techniques has demonstrated activity in the microwave regime (i.e. negative imaginary part of the magnetic susceptibility) for a class of organic compounds. A solution of fullerene (C60) in a liquid crystal solvent has been reported in the literature to possess a maser transition in the X-band region. An external DC magnetic field is required to obtain the effect; the frequency of the maser transition is adjustable by varying the magnetic field strength. We will report on the development of numerical and laboratory tools to evaluate the use of this material for accelerator applications, and evaluate the feasibility of an accelerating structure based on an active microwave medium.  
TPAE043 Production of Terahertz Seed Radiation for FEL/IFEL Microbunchers for Second Generation Plasma Beatwave Experiments at Neptune laser, electron, 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 electron, undulator, 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.

TPAE049 The UCLA/SLAC Ultra-High Gradient Cerenkov Wakefield Accelerator Experiment electron, 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.

TPAE058 Plasma Dark Current in Self-ionized Plasma Wake Field Accelerators (PWFA) plasma, electron, 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.  
TPAP005 Calculation of Residual Dose Rates and Intervention Scenarios for the LHC Beam Cleaning Insertions–Constraints and Optimization insertion, simulation, radioactivity, quadrupole 940
  • M. Brugger, O. Aberle, R.W. Assmann, D. Forkel-Wirth, H.G. Menzel, S. Roesler, H. Vincke
    CERN, Geneva
  Radiation protection of the personnel who will perform interventions in the LHC Beam Cleaning Insertions is mandatory and includes the design of equipment and the establishment of work procedures. Residual dose rates due to activated equipment are expected to reach significant values such that any maintenance has to be planned and optimized in advance. Three-dimensional maps of dose equivalent rates at different cooling times after operation of the LHC have been calculated with FLUKA. The simulations are based on an explicit calculation of induced radioactivity and of the transport of the radiation from the radioactive decay. The paper summarizes the results for the Beam Cleaning Insertions and discusses the estimation of individual and collective doses received by personnel during critical interventions, such as the exchange of a collimator or the installation of Phase 2. The given examples outline the potential and the need to optimize, in an iterative way, the design of components as well as the layout of the beam cleaning insertions. Furthermore, results of measurements and simulations of residual dose rates for a collimator test recently performed at the SPS are presented.  
TPAP006 Detecting Impacts of Proton Beams on the LHC Collimators with Vibration and Sound Measurements proton, collimation, acceleration, beam-losses 1018
  • S. Redaelli, O. Aberle, R.W. Assmann, A.M. Masi, G. Spiezia
    CERN, Geneva
  The 350 MJ stored energy of the 7 TeV LHC beams can seriously damage the beam line elements in case of accidental beam losses. Notably, the LHC collimators, which sit at 6 to 7 σs from the beam centre (1.2-1.4 mm), might be hit and possibly damaged in case of failures, with a consequent degradation of their cleaning performance. The experience from operating machines shows that an a-posteriori identification of the damaged collimators from the observed performance degradation is extremely challenging. Collimator tests with beam at the SPS have proven that the impact of 450 GeV proton beams at intensities from 1010 to 3x1013 can be detected by measuring the collimator vibrations. This was achieved by using high-resolution, radiation hard accelerometers and a microphone to record mechanical and sound vibrations of a LHC-like prototype collimator with impacting beams at different intensities and depth. A similar system could be also used in the LHC to detect collimators damaged by the beam.  
TPAP046 Towards an Optimization of the LHC Intersection Region using New Magnet Technology quadrupole, dipole, insertion, lattice 2920
  • P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, Texas
  • J.-P. Koutchouk
    CERN, Geneva
  An optimized design of the intersection region of LHC is presented. The starting point of the design is to move the quadrupole triplet to a minimum distance from the intersect – 12 m. The innermost quadrupole must accommodate substantial heat load from particles, and is designed using a structured cable that incorporates internal refrigeration with supercritical helium. Using the reduced aperture required by this closer spacing, Nb3Sn quadrupoles have been designed with gradients of 350-400 T/m for the triplet. The separation dipole utilizes a levitated-pole design that mitigates the extreme heat and radiation challenges for that application. The above technical elements have been incorporated into an optimized insertion design that minimizes ?* while significantly reducing sensitivities to errors in multipoles and alignment. The additional space that is opened in the lattice can be used to fully localize the optical design of the insertion so that it does not require corrections through the neighboring arcs.  
TPAT035 Coherent Synchrotron Radiation from an Electron Beam in a Curved Waveguide electron, 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).

TPAT042 Progress on a Vlasov Treatment of Coherent Synchrotron Radiation from Arbitrary Planar Orbits synchrotron, synchrotron-radiation, emittance, lattice 2699
  • G. Bassi, J.A. Ellison
    UNM, Albuquerque, New Mexico
  • R.L. Warnock
    SLAC, Menlo Park, California
  Funding: Support from DOE grants DE-AC02-76SF00515 and DE-FG02-99ER1104 is gratefully acknowledged.

We study the influence of coherent synchrotron radiation (CSR) on particle bunches traveling on arbitrary planar orbits between parallel conducting plates (shielding). The time evolution of the phase space distribution is determined by solving the Vlasov-Maxwell equations in the time domain. This provides lower numerical noise than the macroparticle method, and allows the study of emittance degradation and microbunching in bunch compressors. We calculate the fields excited by the bunch in the lab frame using a formula simpler than that based on retarded potentials.* We have developed an algorithm for solving the Vlasov equation in the beam frame using arc length as the independent variable and our method of local characteristics (discretized Perron-Frobenius operator).We integrate in the interaction picture in the hope that we can adopt a fixed grid. The distribution function will be represented by B-splines, in a scheme preserving positivity and normalization of the distribution. The transformation between lab and beam frame is carefully treated. Here we report on our implementation of the algorithm for a chicane bunch compressor with linear energy chirp and take steps to treat the nonlinear case.

*"Vlasov Treatment of Coherent Synchrotron Radiation from Arbitrary Planar Orbits" to be published in the Proceedings of ICAP04, St. Petersburg, R. Warnock, G. Bassi and J. A. Ellison.

TPAT086 Enhanced Optical Cooling of Particle Beams in Storage Rings undulator, kicker, pick-up, betatron 4179
  • E.G. Bessonov
    LPI, Moscow
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  In this scheme undulators are installed in straight sections of a storage ring at distances determined by a phase advance 2pπ+π between first and second undulators and 2π between next undulators, where p=1,2,3.. . UR emitted in the first undulator pass through an optical system with movable screens 1,2 in the image plane of the particle beam. If screens let pass the UR then the past UR is amplified and pass through the second and next undulators together with the particle. Every particle loses its energy in the overlapped fields of the amplified UR and these undulators. Motion of screens in the optical system leads to particle energy losses in second and following undulators similar to losses in moving targets T1,2 in the schemes of enhanced ion cooling.* Energy losses are accompanied by a decrease of both energy spread and amplitudes of betatron oscillations that is enhanced cooling if, at first, the moving screen 2 will produce conditions of the energy loss for higher energy particles. When the screen 2 will open image of all particles the system must be closed and then the cooling process can be repeated*.


TOAB002 First Results from the VUV FEL at DESY electron, 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.  
TOAB004 An Optimized Low-Charge Configuration of the Linac Coherent Light Source emittance, linac, undulator, gun 344
  • P. Emma, Z. Huang, C. Limborg-Deprey, J. Wu
    SLAC, Menlo Park, California
  • W.M. Fawley, M.S. Zolotorev
    LBNL, Berkeley, California
  • S. Reiche
    UCLA, Los Angeles, California
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

The Linac Coherent Light Source (LCLS) is an x-ray free-electron laser (FEL) project based on the SLAC linac. The nominal parameter set is founded on a 1-nC bunch charge and normalized emittance of about 1 micron. The most challenging issues, such as emittance generation, wakefields, and coherent synchrotron radiation (CSR), are associated with the high bunch charge. In the LCLS in particular, with its strong linac wakefields, the bunch compression process produces sharp temporal horns at the head and tail of the bunch with degraded local emittance, effectively wasting much of the charge. The sharp horns intensify CSR in the bends and further drive a strong resistive-wall wakefield in the long FEL undulator. Although these issues are not insurmountable, they suggest a lower bunch charge may be more suitable. This study uses a 0.2-nC bunch charge and 0.85-micron emittance with only 30 A of peak current in the injector, producing the same FEL saturation length. The resulting performance is more stable, has negligible resistive-wall wakefield, greatly reduced CSR effects, and no transverse wakefield emittance dilution in the linac, with no change to the baseline engineering design.

TOAB007 Femtoslicing in Storage Rings electron, laser, 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.

TOAB009 Generation of Short X-Ray Pulses Using Crab Cavities at the Advanced Photon Source optics, emittance, sextupole, simulation 668
  • K.C. Harkay, M. Borland, Y.-C. Chae, G. Decker, R.J. Dejus, L. Emery, W. Guo, D. Horan, K.-J. Kim, R. Kustom, D.M. Mills, S.V. Milton, G. Pile, V. Sajaev, S.D. Shastri, G.J. Waldschmidt, M. White, B.X. Yang
    ANL, Argonne, Illinois
  • A. Zholents
    LBNL, Berkeley, California
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

There is growing interest within the user community to utilize the pulsed nature of synchrotron radiation from storage ring sources. Conventional third-generation light sources can provide pulses on the order of 100 ps but typically cannot provide pulses of about 1 ps that some users now require to advance their research programs. However, it was recently proposed by A. Zholents et al. to use rf orbit deflection to generate subpicosecond X-ray pulses.* In this scheme, two crab cavities are used to deliver a longitudinally dependent vertical kick to the beam, thus exciting longitudinally correlated vertical motion of the electrons. This makes it possible to spatially separate the radiation coming from different longitudinal parts of the beam. An optical slit can then be used to slice out a short part of the radiation pulse, or an asymetrically cut crystal can be used to compress the radiation in time. In this paper, we present a feasibility study of this method applied to the Advanced Photon Source. We find that the pulse length can be decreased down to a few-picosecond range using superconducting crab cavities.

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

TOAB010 Research and Development of Variable Polarization Superconducting Undulator at the NSLS undulator, polarization, photon, synchrotron 734
  • S. Chouhan, D.A. Harder, G. Rakowsky, J. Skaritka, T. Tanabe
    BNL, Upton, Long Island, New York
  Funding: Office Of Science.

In this work a new concept for the construction of planar variable polarization superconductive insertion device is presented. The construction of the device with 8 mm gap and magnetic period of 26 mm is described compared with permanent magnet insertion device with the same gap & period length, as well as with previously published concepts. Advantage of this design include: (1) electrical tunability for both right and left circular and elliptical, as well as linear vertical or horizontal, (2) it requires no compensation of unwanted vertical field component and (3) used only simple windings of superconductive wire in an interlaced pattern. As a first step towards the construction of full-length device we propose to build & test a short prototype that will serve as a proof of the concept for versatile variable polarization superconductor magnet.

TOAD004 The Possibility of Noninvasive Micron High Energy Electron Beam Size Measurement Using Diffraction Radiation target, electron, 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 electron, 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.

TOPC003 Beam Measurements and Upgrade at BL 7.2, the Second Diagnostics Beamline of the Advanced Light Source synchrotron, synchrotron-radiation, emittance, diagnostics 281
  • T. Scarvie, A. Biocca, N. Kelez, M.C. Martin, T. Nishimura, G.J. Portmann, F. Sannibale, E. Williams
    LBNL, Berkeley, California
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

Beamline BL 7.2 of the Advanced Light Source (ALS) at the Lawrence Berkeley National Laboratory is a beam diagnostics system that uses the synchrotron radiation (SR) emitted by a dipole magnet. It consists of two branches, in the first one the x-ray portion of the SR is used in a pinhole camera system for measuring the transverse profile of the beam. The second branch is equipped with a x-ray BPM system and with a multipurpose port where the visible and the infrared part of the SR can be used for various applications such as bunch length measurements and IR coherent synchrotron radiation experiments. The pinhole system has been commissioned at the end of 2003 and since then is in successful operation. The installation of the second branch has been completed recently and the results of its commissioning are presented in this paper together with examples of beam measurements performed at BL 7.2.

TOPB001 Methods of Attosecond X-Ray Pulse Generation electron, laser, undulator, wiggler 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.

TOPB004 Overview of Energy Recovery Linacs electron, emittance, linac, gun 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.

TPPE017 A New Broadband Microwave Frequency Device for Powering ECR Ion Sources ion, ion-source, injection, electron 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.

TPPE019 Laser Ion Source Development for ISOL Systems at RIA laser, ion, ion-source, target 1640
  • Y. Liu, C. Baktash, J.R. Beene, H. Z. Bilheux, C.C. Havener, H.F. Krause, D.R. Schultz, D.W. Stracener, C.R. Vane
    ORNL, Oak Ridge, Tennessee
  • K. Brueck, Ch. Geppert, T. Kessler, K. Wendt
    Johannes Gutenberg University Mainz, Mainz
  Funding: Managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725.

The isobaric purity of radioactive ion beams (RIBs) is of crucial importance to many experiments. Laser ion sources based on resonant photoionization have already proved to be of great value at existing ISOL RIB facilities. In these ion sources, ions of a selected isotope are produced by laser radiation via stepwise atomic resonant excitations followed by ionization in the last transition. Because each element has its own unique atomic energy levels, the resonant photoionization process can provide elemental selectivity of nearly 100%. We have initiated a research effort to develop a prototype laser ion source with the potential to achieve the high selectivity and high efficiency required for research with ISOL-generated RIBs at the Rare Isotope Accelerator (RIA). A pilot experiment has been conducted to demonstrate resonant photoionization of three atomic species using all-solid-state tunable Ti:Sapphire lasers. Three Ti:Sapphire lasers were provided by the University of Mainz and used in the experiment for three-photon resonant ionization of the elements. Laser generated Sn, Ni, and Ge ions have been successfully obtained in a hot-cavity laser ion source with overall efficiencies of 22%, 2.7%, and 3.3%, respectively.

TPPP004 Study of the Beam-Beam Effect for Crab Crossing in KEKB and Super KEKB luminosity, coupling, damping, simulation 925
  • K. Ohmi, Y. Funakoshi, M. Tawada
    KEK, Ibaraki
  Luminosity upgrade using crab cavities is planned at KEK-B factory (KEKB)in 2006. The crab crossing is expected to increase the beam-beam parameter >0.1, which is twice of present value, for KEKB. We discuss torelances of crab cavities and lattice to get the high beam-beam parameter.  
TPPP029 A Preliminary Interaction Region Design for a Super B-Factory background, luminosity, interaction-region, synchrotron 2077
  • M.K. Sullivan, M.H. Donald, S. Ecklund, A. Novokhatski, J. Seeman, U. Wienands
    SLAC, Menlo Park, California
  • M.E. Biagini
    INFN/LNF, Frascati (Roma)
  Funding: work supportted by the Department of Energy under contract number DE-AC03-76SF00515.

The success of the two B-Factories (PEP-II and KEKB) has encouraged us to look at design parameters for a B-Factory with a 30-50 times increase in the luminosity of the present machines (L~1e36). In order to achieve this high luminosity, the beta y* values are reduced to 3-2 mm, the bunch spacing is minimized (0.6-0.3 m) and the bunch currents are increased. Total beam currents range from 5-25 A. The interaction region (IR) of these "SuperB" designs presents special challenges. Synchrotron radiation fans from local bending in shared magnets and from upstream sources pose difficulties due to the high power levels in these fans. High-order-mode(HOM)heating, effects that have been seen in the present B-factories, will become much more pronounced with the very short bunches and high beam currents. Masking the detector beam pipe from synchrotron radiation must take into account effects of HOM power generation. Backgrounds that are a function of the luminosity will become very important. We present an initial design of an IR with a crossing angle of ± 14 mrad and include a discussion of the constraints, requirements and concerns that go into designing an IR for these very high luminosity e+e- machines.

TPPP042 Synchrotron Radiation in eRHIC Interaction Region photon, synchrotron, synchrotron-radiation, interaction-region 2729
  • J. Beebe-Wang, C. Montag
    BNL, Upton, Long Island, New York
  • A. Deshpande
    Stony Brook University, Stony Brook
  • D.J. Rondeau
    Binghamton University, State University of New York, Binghamton, New York
  • B. Surrow
    MIT, Cambridge, Massachusetts
  Funding: Work performed under the auspices of the US DOE.

The eRHIC currently under study at BNL consists of an electron storage ring added to the existing RHIC complex. The interaction region of this facility has to provide the required low-beta focusing while accommodating the synchrotron radiation generated by beam separation close to the interaction point. In the current design, the synchrotron radiation caused by 10GeV electrons bent by low-beta triplet magnets will be guided through the interaction region and dumped 5m downstream. However, it is unavoidable to stop a fraction of the photons at the septum where the electron and ion vacuum system are separated. In order to protect the septum and minimize the backward scattering of the synchrotron radiation, an absorber and collimation system will be employed. In this paper, we first present the overview of the current design of the eRHIC interaction region with special emphasis on the synchrotron radiation. Then the initial design of the absorber and collimation system, including their geometrical and physical properties, will be described. Finally, our initial investigation of synchrotron radiation in the eRHIC interaction region, especially a simulation of the backward scattering from the absorber, will be presented.

TPPP044 Interaction Region Design for the Electron-Light Ion Collider ELIC electron, synchrotron, synchrotron-radiation, quadrupole 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 electron, 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.

TPPT016 Development of Co-Based Amorphous Core for Untuned Broadband RF Cavity impedance, acceleration, medical-accelerators 1511
  • T. Misu, M. Kanazawa, A. Sugiura, S. Yamada
    NIRS, Chiba-shi
  • K. Katsuki, K. S. Sato
    Toshiba, Yokohama
  We have developed a co-based amorphous core as a new magnetic-alloy (MA) core for the loaded RF cavity. Because of its permeability found to be approximately twice as high as that of FINEMET, this MA core is an excellent candidate for constructing a compact broadband RF cavity with less power consumption. In this report, we present our recent studies of the co-based amorphous core’s physical properties, performance, and development.  
TPPT062 High Power Test of the Prototype Cryomodule for ADS Superconducting Linac linac, target, klystron, feedback 3579
  • E. Kako, S. Noguchi, N. Ohuchi, T. Shishido, K. Tsuchiya
    KEK, Ibaraki
  • N. Akaoka, H. Kobayashi, N. Ouchi
    JAERI/LINAC, Ibaraki-ken
  • E. Chishiro, T. Hori, M. Nakata, M. Yamazaki
    JAERI, Ibaraki-ken
  A prototype cryomodule containing two 9-cell superconducting cavities of beta=0.725 and fo=972MHz had been constructed under the collaboration of Japan Atomic Energy Research Institute (JAERI) and High Energy Accelerator Research Organization (KEK) on the development of superconducting LINAC for Accelerator Driven System (ADS). Cool-down tests to 2.0K of the cryomodule and high power tests with a 972MHz pulsed klystron have been successfully carried out. Rf power of 350kW in a pulsed operation of 3msec and 25Hz was transferred to the nine-cell cavity through an input coupler. Accelerating gradients of about 14MV/m higher than the specification (10MV/m) were achieved in both cavities. Design and performance of the prototype cryomodule and the test results with high rf power will be reported.  
TPPT073 Testing of the New Tuner Design for the CEBAF 12 GeV Upgrade SRF Cavities vacuum, SNS, coupling, higher-order-mode 3910
  • E. Daly, G.K. Davis, W.R. Hicks
    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.

The new tuner design for the 12 GeV Upgrade SRF cavities consists of a coarse mechanical tuner and a fine piezoelectric tuner. The mechanism provides a 30:1 mechanical advantage, is pre-loaded at room temperature and tunes the cavities in tension only. All of the components are located in the insulating vacuum space and attached to the helium vessel, including the motor, harmonic drive and piezoelectric actuators. The requirements and detailed design are presented. Measurements of range and resolution of the coarse tuner are presented and discussed.

TOPA005 Left-Handed Metamaterials Studies and their Application to Accelerator Physics electron, 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.

TOPA011 Self Consistent Scheme for Obtaining Electron-Positron Collisions with Multi-TeV Energy laser, acceleration, photon, damping 740
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  We describe here a self-consistent scheme for arrangement of multi-TeV collisions of electrons and positrons by using laser burst swept along microstructures with stable rate of acceleration ~10GeV/m. Shown that all component of the scheme are within present day technology. For energy ~1TeV luminosity could reach 1035 /cm2/s with wall-plug power of few tens of kW only.  
WPAE003 The Cryogenic Supervision System in NSRRC synchrotron, synchrotron-radiation 844
  • H.C. Li, S. H. Chang, W. S. Chiou, F.-Z. Hsiao, Z.-D. Tsai
    NSRRC, Hsinchu
  The helium cryogenic system in NSRRC is a fully automatic PLC system using the Siemens SIMATIC 300 controller. Modularization in both hardware and software makes it easy in the program reading, the system modification and the problem debug. Based on the Laview program we had developed a supervision system taking advantage of the Internet technology to get system’s real-time information in any place. The functions of this supervision system include the real-time data accessing with more than 300 digital/analog signals, the data restore, the history trend display, and the human machine interface. The data is accessed via a Profibus line connecting the PLC system and the supervision system with a maximum baud rate 1.5 Mbit/s. Due to this supervision system, it is easy to master the status of the cryogenic system within a short time and diagnose the problem.  
WPAE012 Gamma-Ray Irradiation Experiments of Collimator Key Components for the 3GeV-RCS of J-PARC beam-losses, vacuum, proton, synchrotron 1309
  • M. Kinsho, F. Masukawa, N. Ogiwara, O. Takeda, K. Yamamoto
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • J. Kusano
    Japan Atomic Energy Institute, Linac Laboratory, Tokai-Mura
  The turbo molecular pump and the stepping motor which can be operated exposed to high radiation has been under development at JAERI for use in the 3GeV-RCS of the J-PARC. In order to determine the extent of radiation damage to those instruments, gamma-ray irradiation testing was performed at JAERI. It was succeed that the turbo molecular pump and stepping motor could operate properly when given an absorption dose more than 15 MGy in a gamma-ray irradiation environment.  
WPAE013 Development of the Collimator System for the 3GEV Rapid Cycling Synchrotron shielding, electron, 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.  
WPAE016 Development of a Precision Amplifier for the Detector synchrotron, synchrotron-radiation, feedback, ion 1514
  • K.-H. Park, C.W. Chung, S.-M. Hong, S.-H. Jeong, Y.G. Jung, D.E. Kim, H.-S. Lee, W.W. Lee
    PAL, Pohang, Kyungbuk
  • B.-K. Kang
    POSTECH, Pohang, Kyungbuk
  A high gain trans-resistance amplfier has been developed for measuring the intensity of synchrotron radiation at Pohang Light Source(PLS). This amplifier built with discrete elements and operational amplifiers.It had the capability of measuring range from 1pA to 1 uA with good linearity. A microprocessor was also installed to interface the amplifier with the computer, and controlled the other sub-circuits. The various characteristics of amplifier such as linearity, sensitivity,stability, etc. have been investigated, and its experimental results carried out at the beam line are presented in this paper.  
WPAE018 Performance Tests of Survey Instruments Used in Radiation Fields Around High-Energy Accelerators simulation, shielding, photon, target 1595
  • S. Mayer, D. Forkel-Wirth, M. Fuerstner, H.G. Menzel, S. Roesler, C. Theis, H. Vincke
    CERN, Geneva
  Measurements of ambient dose equivalent in stray radiation fields behind the shielding of high-energy accelerators are a challenging task. Several radiation components (photons, neutrons, charged particles), spanning a wide range of energies, contribute to the total dose equivalent. In routine-measurements, the total dose equivalent is obtained by the combination of several radiation detectors. Ionisation chambers, which are sensitive to all radiation components, are employed together with so-called REM counters, which are responding mainly to neutrons. The total dose equivalent is correctly assessed provided that the response is interpreted carefully by using appropriate corrections and calibration factors. For this reason measurements were carried out in a high-energy reference field at CERN, which allows one to study the response of the different detectors in a mixed radiation field under controlled conditions. In addition, the field was simulated by Monte Carlo simulations. The outcome of these studies serves on one hand as a basis for quality assurance and improves on the other hand the knowledge of the instrument’s response for future applications at the LHC.  
WPAE028 Radiation Issues in the Fermilab Booster Magnets booster, proton, beam-losses, vacuum 2041
  • E. Prebys
    Fermilab, Batavia, Illinois
  Funding: Department of Energy.

The demands of the Fermilab neutrino program will require the 30 year old Fermilab 8 GeV Booster to deliver higher intensities than it ever has. Total proton throughput is limited by radiation damage and activation due to beam loss in the Booster tunnel. Of particular concern is the insulation in the 96 combined function lattice magnets. This poster describes a study of the potential radiation damage to these magnets from extended running at the planned intensities.

WPAE031 Mechanical Design of a Heavy Ion Beam Dump for the RIA Fragmentation Line ion, dipole, heavy-ion, vacuum 2185
  • W. Stein, L. Ahle
    LLNL, Livermore, California
  • D.L. Conner
    ORNL, Oak Ridge, Tennessee
  The RIA fragmentation line requires a beam stop for the primary beam downstream of the first dipole magnet. The beam may consist of U, Ca, Sn, Kr, or O ions. with a variety of power densities. The configuration with highest power density is for the U beam, with a spot size of 3 cm x 3 cm and a total power of up to 300 kW. The mechanical design of the dump that meets these criteria consists of a 50 cm diameter aluminum wheel with water coolant channels. A hollow drive shaft supplies the coolant water and connects the wheel to an electrical motor located in an air space in the floor above the dump. The beam strikes the wheel along the outer perimeter and passes through a thin window of aluminum where 10% of its power is absorbed and the remainder of the beam is absorbed in flowing water behind the window. Rotation of the wheel at 400 RPM results in maximum aluminum temperatures below 100 C and acceptably low thermal stresses of 5 ksi. Rotating the wheel also results in low radiation damage levels by spreading the damage out over the whole perimeter of the wheel. For some of the other beams, a stationary dump consisting of a thin aluminum window with water acting as a coolant and absorber appears to be feasible.  
WPAE034 Fast Neutron Damage Studies on NdFeB Materials radioactivity, permanent-magnet, multipole, hadron 2351
  • J.E. Spencer, S.D. Anderson, R. Wolf
    SLAC, Menlo Park, California
  • A. Baldwin, D.E. Pellet
    UCD, Davis, California
  • M. Boussoufi
    UCD/MNRC, McClellan, California
  • J.T. Volk
    Fermilab, Batavia, Illinois
  Funding: Support of this work was under U.S. Dept. of Energy contracts DE-AC02-76SF00515, DE-AC02-76CH03000 and LCRD contract DE-FG02-03ER41280.

Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large fluences of hadrons, leptons and gammas over the life of the facility. Although the linacs will be superconducting, there are still many potential uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the radiation damage situation for rare earth permanent magnet materials was presented at PAC2003 and our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC2004 where the damage appeared proportional to the distances between the effective operating points and Hc. Here we have extended those doses and included more commercial samples together with the induced radioactivities associated with their respective dopants. Hall probe data for the external induction distributions are compared with vector magnetization measurements for the different materials.

WPAE050 First Calibrations of Alanine and Radio-Photo-Luminescence Dosemeters to a Hadronic Radiation Environment proton, simulation, photon, hadron 3097
  • M. Fuerstner, I. Brunner, D. Forkel-Wirth, S. Mayer, H.G. Menzel, H. Vincke
    CERN, Geneva
  • I. Floret
    Ecole d'ingénieurs de Genève, Genève
  Alanine and Radio-Photo-Luminescence (RPL) dosimeters are used to monitor radiation doses occurring inside the tunnels of all CERN accelerators including the Large Hadron Collider (LHC). They are placed close to radiation sensitive machine components like cables or insulation of magnet coils to predict their remaining lifetime. The dosimeters are exposed to mixed high-energy radiation fields. However, up to now both dosimeter types are calibrated to 60Co-photons only. In order to study the response of RPL and alanine dosimeters to mixed particle fields like those occurring at CERN’s accelerators, an irradiation campaign at the CERN-EC High-Energy Reference field Facility (CERF-field) was performed. Moreover, the dosimeters were first time calibrated to a proton radiation field of a constant momentum of 24 GeV/c. In addition to the experiment FLUKA Monte Carlo simulations were carried out, which provide information concerning the energy deposition and the radiation field at the dosimeter locations.  
WPAE053 Neutronics Assessments for a RIA Fragmentation Line Beam Dump Concept multipole, heavy-ion, proton, ion 3227
  • J.L. Boles, L. Ahle, S. Reyes, W. Stein
    LLNL, Livermore, California
  Funding: Work 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.

Heavy ion and radiation transport calculations are in progress for conceptual beam dump designs for the fragmentation line of the proposed Rare Isotope Accelerator (RIA). Using the computer code PHITS, a preliminary design of a motor-driven rotating wheel beam dump and adjacent downstream multipole has been modeled. Selected results of these calculations are given, including neutron and proton flux in the wheel, absorbed dose and displacements per atom in the hub materials, and heating from prompt radiation and from decay heat in the multipole.

WPAE054 Irradiation Effects on RIA Fragmentation Cu Beam Dump ion, heavy-ion, target, simulation 3265
  • S. Reyes, L. Ahle, J.L. Boles, W. Stein
    LLNL, Livermore, California
  • B.D. Wirth
    UCB, Berkeley, California
  Funding: U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

Within the scope of conceptual R&D activities in support of the Rare-Isotope Accelerator (RIA) facility, high priority is given to the development of high-power fragmentation beam dumps. A pre-study was made of a static water-cooled Cu beam dump that can meet requirements for a 400 MeV/u uranium beam. The issue of beam sputtering was addressed and found to be not a significant issue. Preliminary radiation transport simulations show significant damage (dpa) in the vicinity of the Bragg peak of uranium ions. Experimental data show that defects in Cu following neutron or high-energy particle irradiation tend to saturate at doses between 1 and 5 dpa, and this saturation in defect density also results in saturation of mechanical property degradation. However, effects of swift heavy ion irradiation and the production of gaseous and solid transmutant elements still need to be addressed. Initial calculations indicate that He concentrations on the order of 100 appm are produced in the beam dump after several weeks of continuous operation and He embrittlement should be a concern. Recommendations are made for further investigation of Cu irradiation effects RIA-relevant conditions.

WPAE062 AC Power Supply for Wobbler Magnet of the MC-50 Cyclotron power-supply, cyclotron, ion, target 3576
  • Y.-S. Kim, J.-S. Chai
    KIRAMS, Seoul
  • C.W. Chung, H.-G. Lee, W.W. Lee, K.-H. Park
    PAL, Pohang, Kyungbuk
  • B.-K. Kang
    POSTECH, Pohang, Kyungbuk
  The MC-50 cyclotron (k=50) produces the ion beam for nuclear physics, chemistry, and applied researches in Korea. It has a small beam diameter with Gaussian beam shape, whereas many users want a beam irradiation on a large target. A wobbler magnet and an AC power supply were designed and constructed to meet the users’ requirement. The power supply has two independently operating channels for the vertical and horizontal coils of the wobbler magnet. The frequency of the AC power supply for both coils is programmable from 1 to 20 Hz in a step of 1 Hz, and the maximum rms output current is 12 A. Various properties of the power supply and experimental results are given in the paper.  
WPAP011 SPARC Working Point Optimization for a Bunch with Gaussian Temporal Profile emittance, simulation, electron, 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.  
WPAP023 Compact Source of Electron Beam with Energy of 200 kEv and Average Power of 2 kW electron, ion, focusing, power-supply 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.  
WPAT009 Status of the RF System for the 6.5 GeV Synchrotron Light Source PF-AR synchrotron, vacuum, coupling, synchrotron-radiation 1168
  • S. Sakanaka, K. Ebihara, S. Isagawa, M. Izawa, T. Kageyama, T. Kasuga, H. Nakanishi, M. Ono, H. Sakai, T. Takahashi, K. Umemori, S.I. Yoshimoto
    KEK, Ibaraki
  The Photon Factory Advanced Ring (PF-AR) is a 6.5-GeV synchrotron light source at KEK. An rf system comprises two 1.2-MW klystrons, six alternating-periodic-structure (APS) cavities, and other components. It supplies an rf voltage of about 15 MV with a beam current of 60 mA. The system has been working well, except for a trouble (frequent trips with beams) in one of the cavities. We found that the trips were triggered by an irradiation of synchrotron radiation to the cavity wall. In the summer of 2004, we reorganized the rf system, which allows us to install two insertion devices in a part of the rf sections. We replaced the troubled cavity at a time. We report both the operation status and the modification of the rf system.  
WPAT075 Design and Calibration of a Phase and Amplitude Detector linac, klystron, shielding
  • Z. Geng, P. Gu, H.Mi. Hou, G. Pei
    IHEP Beijing, Beijing
  The phase and amplitude detector (PAD) is a key unit of the phasing system for BEPCII linac. One of the main functions of the PAD is to measure the phase of each klystron accurately from such large noises. To meet the need of the phasing system, a new PAD is constructed based on I/Q demodulator and industrial computer. But the I/Q demodulator suffers form phase and amplitude mismatch, which can draw big error on phase measurement. In order to compensate the mismatch of the I/Q demodulator, we develop a calibration program using an adaptive method, LMS method. Almost all the mismatches of the I/Q demodulator are compensated after calibration.  
WPAT085 4.2 K Operation of the SNS Cryomodules SNS, linac, controls, Spallation-Neutron-Source 4173
  • I.E. Campisi, S. Assadi, F. Casagrande, M. Champion, C. Chu, S.M. Cousineau, M.T. Crofford, C. Deibele, J. Galambos, P.A. Gurd, D.R. Hatfield, M.P. Howell, D.-O. Jeon, Y.W. Kang, K.-U. Kasemir, Z. Kursun, H. Ma, M.F. Piller, D. Stout, W.H. Strong, A.V. Vassioutchenko, Y. Zhang
    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 Spallation Neutron Source being built at the Oak Ridge National Laboratory employs eighty one 805 MHz superconducting cavities operated at 2.1 K for the H- beam to gain energy in the main linac from 187 MeV to about 1 GeV. The superconducting cavities and cryomodules with two different values of beta .61 and .81 have been designed and constructed at Jefferson Lab for operation at 2.1 K with unloaded Q’s in excess of 5x109. To gain experience in testing cryomodules in the SNS tunnel before the final commissioning of the 2.1 K Central Helium Liquefier, integration tests were conducted on a medium beta (.61) cryomodule at 4.2 K. This is the first time that a superconducting cavity system specifically designed for 2.1 K operation has been extensively tested at 4.2 K without superfluid helium. Even at 4.2 K it was possible to test all of the functional properties of the cryomodule and of the cavities. In particular, at a nominal BCS Qo˜7x108, simultaneous pulse operation of all three cavities in the cryomodule was achieved at accelerating gradients in excess of 12 MV/m. These conditions were maintained for several hours at a repetition rate of 30 pps. Details of the tests will be presented and discussed.

WPAT086 Superconducting RF Cavity Frequency and Field Distribution Sensitivity Simulation simulation, SNS, superconducting-RF, resonance 4194
  • S. An
    ORNL, Oak Ridge, Tennessee
  Funding: Under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

Frequency and electromagnetic field distribution sensitivity of a superconducting RF (SRF) cavity due to cavity’s small deformation are the fundamental phyical paramethers in cavity and tuner design. At low temperature, the frequency sensitivity can be obtained by measuring prototype cavity, but it is not easy to test the filed distribution sensitivity. This paper presents and describes a simulation method combining ANSYS and SUPERFISH to calculate the cavity frequency and field distribution variation due to cavity’s small deformation caused by mechanical force, radiation force, thermal expansion etc.. As an example, the simulation results of the frequency and field flatness sensitivity on the SNS cavities were confirmed by their test results.


ROAC001 Testing of the SNS Superconducting Cavities and Cryomodules SNS, linac, Spallation-Neutron-Source, vacuum 34
  • I.E. Campisi
    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 superconducting linac for the Spallation Neutron Source is in the process of being commissioned. Eighty-one cavities resonating at 805 MHz are installed in the SNS tunnel in 11 medium beta (.61) cryomodules each containing 3 cavities and 12 high beta (.81) cryomodules each with 4 cavities. The niobium cavities and cryomodules were designed and assembled at Jefferson Lab and installed in the SNS tunnel at Oak Ridge and are operating at 2.1 K. A preliminary test of one medium beta cryomodule was performed at 4.2 K in September 2004. All functional parameters of the cryomodule were proven to meet specifications at that temperature. The Central Helium Liquefier is being commissioned for 2.1 K operation and all cavities will be tested by late Spring 2005. The testing will include all of the functional parameters necessary for beam operation, to be carried out in summer 2005. The focus of the testing is to characterize the cavities’ maximum gradients and that sustained simultaneous operation can be achieved for all the cavities in preparation of beam commissioning. The results of cryomodule and cavity testing in the superconducting linac will be presented.

RPAE001 On the Issue of Phasing of Undulators at the Advanced Photon Source undulator, brilliance, electron, 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.

RPAE004 Parametric Mechanical Design of New Insertion Devices at the APS undulator, insertion, insertion-device, brilliance 889
  • J.H. Grimmer, R.T. Kmak
    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.

Three permanent-magnet, planar, hybrid ID designs have recently been completed at the APS. The periods of the devices are 2.7 cm, 3.0 cm and 3.5 cm with nominal lengths of 2.4 m. Several design studies were performed for the initial 2.7 cm period device to investigate the utility of various design features. Then a parametric solid model for the initial device was developed and value engineered to minimize manufacturing, assembly and tuning costs. The model allowed the very rapid design of subsequent devices of similar periods and allowed commonality of several components of the IDs. This design family incorporates a low-cost method of pole retention and registration. Poles are secured by screws in two holes tapped into each pole. Pole location is registered by means of two small dowel pins for each pole in mating holes reamed into each pole and a base plate common to the poles and magnets. This base plate is flexible in bending along its length so shimming behind it can be used to accurately change the height of a pair of poles for tuning. Another feature of the design is modular construction to allow each device to be used full-length or shortened to a nominal 2.1 m length for use in APS "canted undulator" sectors.

RPAE005 The possibility for a Short-Period Hybrid Staggered Undulator undulator, brilliance, permanent-magnet, photon 982
  • S. Sasaki
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Dept. of Energy under Contract No. W-31-109-ENG-38.

Much work is underway to develop superconducting undulators in order to generate brilliant hard x-ray radiation at many synchrotron radiation facilities. However, in spite of many R&D efforts, it might take several years to reach this goal. On the other hand, the possibilities of cryogenic permanent magnet undulators are being investigated in order to provide an interim solution for hard x-ray users’ needs at Spring-8 and other facilities. However, although the in-vacuum undulator technology is well established, the in-vacuum gap-motion mechanism at a low temperature might cause major concerns regarding reliability and cost effectiveness. In this paper, the possibility for a cryogenic short-period staggered undulator was investigated. A simple model calculation by RADIA* shows that the effective undulator field is 0.825 T for a 15-mm-period staggered undulator at 6 mm gap with 1.36 T solenoid field. The pole material was assumed to be dysprosium, which has a saturation magnetization of 3.3 T at 77 K. The achievable maximum field of this simply structured device is close to that of a cryogenic permanent magnet undulator. We present calculated performances of cryogenic staggered undulators at various periods and gaps.

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

RPAE016 Smith-Purcell Radiation from a Charge Moving Above a Finite-Length Grating resonance, electron, 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, betatron, electron 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 electron, scattering, 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 electron, positron, plasma, 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, electron, scattering, 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 electron, undulator, 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, electron, optics 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 electron, laser, 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, electron, polarization, 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, electron, 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.

RPAE036 Damping Wigglers for the PETRA III Light Source wiggler, damping, emittance, synchrotron 2446
  • M. Tischer, K. Balewski, W. Decking, M. Seidel, L. Yongjun
    DESY, Hamburg
  • V. Kuzminykh, E. Levichev, P. Vobly, K. Zolotariov
    BINP SB RAS, Novosibirsk
  Within the reconstruction of the PETRA booster ring at DESY towards a third generation light source after 2007, damping wigglers will be installed to reduce the emittance to a value of 1 nmrad. Two damping sections in the long straights of PETRA have been assigned to accommodate 20 wigglers in total. The wigglers will be permanent magnet devices with a fixed gap which are surrounded by an iron enclosure to reduce the leakage flux. Each wiggler will provide a damping integral of 4 T2m per segment and generate a synchrotron radiation power of 42 kW. A short one period long prototype has recently been built to prove the magnetic design and study the correction scheme for tuning the pole strength. The wiggler segments will be followed by an SR absorber shading the downstream quadrupole and successive wiggler segment, the accumulated on-axis power of about 200 kW will be taken up by the final absorber at the damping section end.  
RPAE038 Far Infrared Coherent Synchrotron Edge Radiation at ANKA synchrotron, storage-ring, synchrotron-radiation, optics 2518
  • A.-S. Müller, I. Birkel, B. Gasharova, E. Huttel, R. Kubat, Y.-L. Mathis, W. Mexner, D.A. Moss, F. Pérez, R. Rossmanith, P. Wesolowski, M. Wuensch
    FZK, Karlsruhe
  • C. J. Hirschmugl
    UWM, Milwaukee, Wisconsin
  • M. Pont
    CELLS, Bellaterra (Cerdanyola del Vallès)
  A synchrotron radiation source emits coherent infrared (IR) radiation when the electron bunch length is comparable to the wavelength of the emitted radiation. To generate coherent radiation in the far IR (THz) region, a "low alpha mode" has been devised at the ANKA storage ring operating at 1.3 GeV. The corresponding lattice has a significantly reduced momentum compaction factor. The spectral dependence of the emitted radiation is recorded at the ANKA-IR beamline, where the synchrotron light is produced in the fringe field of a bending magnet. This edge radiation has the advantage of being more collimated than constant field radiation. This allows the observation of frequencies down to 1 cm-1 through a modest vertical aperture, which would not be possible with classical constant field emission due to the increasing beam divergence with decreasing frequency. The onset of coherent emission is found at a synchrotron frequency of about 10 kHz. At 5 kHz, an intensity enhancement of up to 5 orders of magnitude, with respect to the incoherent emission, is observed in the spectral range between 1 and 65 cm-1.  
RPAE039 Operation of the ANKA Synchrotron Light Source with Superconductive Undulators undulator, synchrotron, synchrotron-radiation, vacuum 2559
  • R. Rossmanith, MH. Hagelstein, B.K. Kostka, A.-S. Müller, D. Wollmann
    FZK, Karlsruhe
  • T. Baumbach, A. Bernhard
    FZ Karlsruhe, Karlsruhe
  • E. Steffens
    Erlangen University, Erlangen
  • M. Weisser
    University of Erlangen-Nürnberg, Physikalisches Institut II, Erlangen
  The synchrotron light source ANKA (2.5 GeV, 200 mA) is a versatile multi-purpose storage ring with beam lines for coherent IR and THz radiation (IR-laser), LIGA applications and high brilliance X-rays. It is now plannned to install in addition several superconductive undulators for a wide range of applications: fast tunable X-rays for material research, imaging applications and an undulator with variable polarization direction for a dichroism beamline. This development of ANKA is the result of successful research on superconductive undulators which surpass the performance of permanent undulators by far (collaboration between ANKA, the University of Karlsruhe and the University of Erlangen-Nürnberg). The basic layout of the undulators and the required changes to a storage ring to accommodate the superconductive undulators is described in this paper.  
RPAE043 Beam Position Monitor for Undulator by Using SR Monitor Technique undulator, focusing, monitoring, photon 2789
  • T. Mitsuhashi, M.T. Tadano
    KEK, Ibaraki
  A beam position monitor for the undulator by using the optical SR monitor technique has been tested in the Photon Factory. A visible SR in far tail of the undurater spectrum is extracted by a water-cooled beryllium mirror. The extraction mirror has a hole in the center for passing through the central peak of the undulator radiation which has an opening angle of 1/gamma. Extracted visible light in large opening angle has exactly same optical axis of the undulator radiation, because of it’s a far tail of the spectrum of same radiation. We applied focusing system to observe the beam position in the undulator through the optical image of beam. The results show us this method is applicable to monitor a position of beam in the undulator, and gap change of undulator has no effect of beam position monitoring. We can easily measure the angle of visible ray, this method is applicable not only beam position monitor but also monitoring the angular deviation of undulator radiation.  
RPAE045 Production of Short Electron Bunches by Slow and Fast Excitations of Longitudinal Bunch-Shape Oscillations synchrotron, simulation, storage-ring, damping 2887
  • S. Sakanaka, T. Mitsuhashi, T. Obina, K. Umemori
    KEK, Ibaraki
  In the Brookhaven Alternating Gradient Synchrotron (AGS), adiabatic excitation of longitudinal bunch-shape oscillations has been successfully used for extracting shortened proton bunches.* We applied this technique to the electron storage ring. In case of electron machines, growth time of bunch-shape oscillations should be shorter than the radiation damping time for preventing radiation excitation. We demonstrated in the 2.5-GeV Photon Factory storage ring that electron bunches could be shortened by a factor of about two from its natural length using this technique. We show that non-adiabatic excitation of oscillations is also very useful for obtaining shorter bunches.

*M. Bai et al., Phys. Rev. ST Accel. Beams 3, 064001 (2000).

RPAE061 Beam Loss Simulation Studies for ALS Top-Off Operation injection, simulation, electron, 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 electron, 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, lattice, synchrotron, electron 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, electron, synchrotron 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.

RPAE071 Touschek Lifetime and Undulator Damage in the Advanced Photon Source scattering, injection, simulation, lattice 3835
  • M. Borland, L. Emery
    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 Advanced Photon Source (APS) has two insertion devices (IDs) with small-aperture vacuum chambers. The full vertical aperture in these chambers is 5 mm, while the inboard horizontal aperture is 15 mm. These devices suffer significant radiation damage, requiring frequent retuning. We recently hypothesized that the damage resulted from loss of Touschek-scattered particles on the horizontal aperture of the chambers. This results partly from the smallness of the aperture and partly from the pattern of the dispersion and beta functions in the low-emittance APS lattice. The horizontal scrapers were originally at a high-dispersion location, but, in the low-emittance lattice, they are at a fairly low-dispersion location. Similarly, the dispersion at the IDs was originally zero but is now close to the maximum for the lattice. In this paper, we summarize simulations and experiments that support our hypothesis and discuss plans to remedy the problem.

RPAE072 Simulations of X-Ray Slicing and Compression Using Crab Cavities in the Advanced Photon Source sextupole, emittance, photon, synchrotron 3886
  • M. Borland, V. Sajaev
    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.

Recently, Zholents et al. proposed applying to the Advanced Photon Source an x-ray compression scheme based on a pair of crab cavities and asymmetric cut crystals. We have explored the feasibility and potential performance of this scheme through simulation. We used the code elegant to perform 6-D tracking, allowing us to characterize the emittance growth, which is mostly a result of sextupoles between the cavities. We also explored tolerances on alignment, phase, and voltage of the cavities; lifetime effects; tradeoffs between cavity frequency and voltage; and performance with slicing alone instead of compression. Our conclusion is that sub-picosecond rms x-ray pulse lengths should be feasible.

RPAE076 The Commission of Hefei Light Source After Reconstruction injection, closed-orbit, octupole, electron 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.  
RPAE086 Observation of Coherent Synchrotron Radiation at NewSUBARU synchrotron, synchrotron-radiation, electron, 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.  
RPAP018 Identification of Nano-Objects in Substances by Using of X-Ray Electron Radiation electron, 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.

RPAP027 Portable X-Band Linear Electron Accelerators for Radiographic Applications linac, coupling, electron, 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 (1…2) MeV at a high output dose rate. Design and experimental parameters are presented. The common and system specific features are also discussed.  
RPAP035 Photonuclear and Radiation Effects Testing with a Refurbished 20 MeV Medical Electron Linac linac, electron, 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.  
RPAP044 Linearizing the Response of the NSRL Synchronous Recycling-Integrators 2830
  • P. Oddo, A. Rusek, T. Russo
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

The LBNL designed recycling-integrators used for the NSRL dosimetry feature excellent linearity. However, switching transients in the balancing source add a duty-cycle dependence to the response that manifests as a non-linearity near mid-scale and a slope-change above mid-scale. The onset of this non-linearity limits the typical usable dynamic range. Measurements during a recent run showed that at higher intensities the recycling-integrators would operate in the non-linear region enough to exceed the desired tolerance and over count the dose. This report will show how a FPGA, which implements the scalars, was used to compensate the non-linearity allowing higher dose-rates by effectively doubling the dynamic range of the dosimetry system.

RPAP049 Beam Diagnostics with Optical Fiber Optics optics, feedback, synchrotron, synchrotron-radiation 3040
  • Y. Yin
    Y.Y. Labs, Inc., Fremont, California
  Optical fiber has been widely used for communications. It is a waveguide with very high-frequency bandwidth. Therefore, it has broad applications for high-frequency related signals such as high-energy Accelerator beam signls. Research and developments has been done to measure charged particle beam and synchrotron radiation with optical fiber based instruments developed by the author. The paper will describe and discuss the experiments and testing of charged particle beams and synchrotron radiation that haverecently been performed.  
RPAT022 Optical Faraday Cup for Heavy Ion Beams ion, heavy-ion, diagnostics, target 1805
  • F.M. Bieniosek, S. Eylon, P.K. Roy, S. Yu
    LBNL, Berkeley, California
  Funding: Work performed under the auspices of the U.S. Department of Energy by the university of California, Lawrence Berkeley National Laboratory under Contract No. DE-AC03-76F00098.

We have been using alumina scintillators for imaging beams in heavy-ion beam fusion experiments in 2 to 4 transverse dimensions.* The scintillator has limitations on lifetime, linearity, and time response. As a possible replacement for the scintillator, we are studying the technique of imaging the beam on a gas cloud. A gas cloud for imaging the beam may be created on a solid hole plate placed in the path of the beam, or by a localized gas puff. It is possible to image the beam using certain fast-quenching optical spectral lines that closely follow beam current density and are independent of gas density. We describe this technique and show experimental data using a nitrogen line at 394.1 nm. This approach has promise to be a new fast beam current diagnostic on a nanosecond time scale.

*FM Bieniosek, L Prost, W Ghiorso, Beam imaging diagnostics for heavy ion beam fusion experiments, Paper WPPB050, PAC 2003.

RPAT028 RHIC BPM System Modifications and Performance injection, alignment, quadrupole, instrumentation 2021
  • T. Satogata, R. Calaga, P. Cameron, P. Cerniglia, J. Cupolo, A.J. Curcio, W.C. Dawson, C. Degen, J. Gullotta, J. Mead, R.J. Michnoff, T. Russo, R. Sikora
    BNL, Upton, Long Island, New York
  Funding: Work performed under the auspices of the U.S. Department of Energy.

The RHIC beam position monitor (BPM) system provides independent average orbit and turn-by-turn (TBT) position measurements. In each ring, there are 162 measurement locations per plane (horizontal and vertical) for a total of 648 BPM planes in the RHIC machine. During 2003 and 2004 shutdowns, BPM processing electronics were moved from the RHIC tunnel to controls alcoves to reduce radiation impact, and the analog signal paths of several dozen modules were modified to eliminate gain-switching relays and improve signal stability. This paper presents results of improved system performance, including stability for interaction region and sextupole beam-based alignment efforts. We also summarize performance of improved million-turn TBT acquisition channels for nonlinear dynamics and echo studies.

RPAT035 Development of an Optical Transition Radiation Detector for Profile Monitoring of Antiproton and Proton Beams at FNAL proton, target, antiproton, injection 2381
  • V.E. Scarpine, C.W. Lindenmeyer, G. R. Tassotto
    Fermilab, Batavia, Illinois
  • A.H. Lumpkin
    ANL, Argonne, Illinois
  Funding: Work Supported by the U.S. Department of Energy under Contract No. DE-AC02-CH03000 and by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

Optical transition radiation (OTR) detectors are being developed at Fermi National Acceleratory Laboratory (FNAL) as part of the collider Run II upgrade program and as part of the NuMI primary beamline. These detectors are designed to measure 150 GeV antiprotons as well as 120 GeV proton beams over a large range of intensities. Design and development of an OTR detector capable of measuring beam in both directions down to beam intensities of ~5·109 particles for nominal beam sizes is presented. Applications of these OTR detectors as an on-line emittance monitor for both antiproton transfers and reverse-injected protons, as a Tevatron injection profile monitor, and as a high-intensity beam profile monitor for NuMI are discussed. In addition, different types of OTR foils are being evaluated for operation over the intensity range of ~5·109 to over 1·1013 particles per pulse and these are described.

RPAT036 Measurement of the Intensity of the Beam in the Abort Gap at the Tevatron Utilizing Synchrotron Light synchrotron, collider, proton, synchrotron-radiation 2440
  • R. Thurman-Keup, E. Lorman, T. Meyer, S. Pordes
    Fermilab, Batavia, Illinois
  • S. De Santis
    LBNL, Berkeley, California
  Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the U.S. Department of Energy.

The beam bunches in the Tevatron are arranged to provide gaps in time for the abort kickers to ramp to full field. The presence of even a small fraction (few 10-4)of the beam in the abort gaps can induce quenches of the superconducting magnets and inflict severe radiation damage on the silicon detectors of the experiments. Techniques for calibrating and measuring the intensity of the beam in the abort gap using synchrotron light and a gated photomultiplier tube are described. Measurements of the evolution and longitudinal profile of the beam in the abort gap are presented.

RPAT053 Movement of BPMs Due to Thermal Stress in KEKB pick-up, sextupole, luminosity, synchrotron 3253
  • M. Tejima, A. Arinaga, H. Fukuma, S. Hiramatsu, T. Ieiri, I. Ishii, M. Tobiyama
    KEK, Ibaraki
  Movement of Beam Position Monitors (BPM) due to thermal stress in high beam current operation is observed in KEKB. For high luminosity operation of KEKB, the beam current as high as 1.6A is accumulated in the positron ring and a precise control of the beam orbit based on the BPM system is required. Though the every BPM chamber is fixed firmly on a support of each quadrupole magnet, the BPM chamber moves several hundred microns from the setting position depending on the beam current due to beam pipe heating by strong synchrotron light irradiation. Such movement introduces an unavoidable offset error in the BPM measurement, and is a serious problem not only for KEKB but also for the next generation of B-factory operated with extremely high beam current. We report the measurement of the movement by distance sensors and an attempt to correct the BPM offset error in real-time operation.  
RPAT059 The SRI Beam Size Monitor Developed at NSRRC photon, synchrotron, diagnostics, synchrotron-radiation 3465
  • T.C. Tseng, J.-R. Chen, H.C. Ho, C.-K. Kuan, C.J. Lin, S.Y. Perng, D.-J. Wang, J. Wang
    NSRRC, Hsinchu
  A beam size monitor based on the synchrotron radiation interferometer (SRI) was installed in the NSRRC TLS. This monitor consists of a simple diagnostic beamline with a water-cooled beryllium mirror inside and a detecting optical system for both vertical and horizontal beam size measurement. The beam sizes measured are 48 micron and 160 micron respectively and are more close to the theoretical values than the synchrotron image monitor. Comparing with other monitors, at least 1 micron beam size variation is detectable. To minimize the thermal effect, the mirror is located far away from the source point and closed to the detecting optical system. The thermal distortion of the mirror is quite small measured by a portable long trace profiler (LTP) and agrees with the simulating analysis. The detailed monitor system design and testing results are presented in this paper.  
RPAT067 Beam Angle Measurement Using Cherenkov Radiation electron, 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 electron, injection, 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 electron, antiproton, optics, 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 vacuum, electron, 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.

RPAT077 Beam Test Proposal of an ODR Beam Size Monitor at the SLAC FFTB target, photon, optics, monitoring 4015
  • Y. Fukui, D. Cline, F. Zhou
    UCLA, Los Angeles, California
  • A. Aryshev, V. Karataev, T. Muto, M. Tobiyama, J.U. Urakawa
    KEK, Ibaraki
  • P.R. Bolton, M.C. Ross
    SLAC, Menlo Park, California
  • R. Hamatsu
    TMU, Hatioji-shi,Tokyo
  • G.A. Naumenko, A. Potylitsyn, A. Sharafutdinov
    Tomsk Polytechnic University, Physical-Technical Department, Tomsk
  We design a single bunch transverse beam size monitor which will be tested to measure the 29 GeV electron/positron beam at the SLAC FFTB beam line.The beam size monitor uses a CCD camera to make images of the interference pattern of the optical diffraction radiation from conductive slit target which are placed close to the beam path. In this method, destruction of the accelerated electron/positron beam bunches due to the beam size monitoring is negligible, which is vital to the operation of the Linear Collider project. A dis-phased conductive slit target and a lens system allow us to recover the sensitivity of the transverse beam size with a small photon yield ratio at the valley to that at the peak due to the large gamma*λ, and with the near field effect due to the large λ*gamma**2. A solution for non-negligible divergence at the SLAC FFTB is also discussed.  
RPAT078 Bunch Length Measurements Using Coherent Radiation electron, 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 electron, 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.

RPAT080 The SPEAR 3 Diagnostic Beamlines coupling, synchrotron, emittance, optics 4057
  • W.J. Corbett, C. Limborg-Deprey, W.Y. Mok, A. Ringwall
    SLAC, Menlo Park, California
  Funding: Work supported in part by DOE contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.

SPEAR 3 is equipped with an x-ray pinhole camera and a visible/UV beam line to evaluate electron beam properties. The pinhole camera has a 30 x 25 micron Ta aperture and 60% image demagnification on a phosphor screen. The image is captured by a National Instruments frame-grabber on a remote computer with a parallel video signal for control room monitoring. The visible/UV beam line features a horizontal ± 0.3 mrad ‘cold finger’ to remove the x-ray core of the beam. The remaining visible/UV light is deflected 18 degrees onto an optical bench where it is focused via refractive Cassegrain optics. The beam is then split into parallel optics for gated- and streak camera measurements. This paper describes the experimental set up and preliminary measurements obtained with both systems.

RPAT082 Coherent Transition Radiation To Measure the SLAC Electron Bunch Length electron, 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.

RPAT085 Initial Imaging of 7-GeV Electron Beams with OTR/ODR Techniques at APS dipole, booster, electron, 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.

RPAT087 Design of a High-Resolution Optical Transition Radiation Imager System for the Linac Coherent Light Source Undulator electron, undulator, optics, 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).

RPAT090 The Study of New Signal Processing Technique in Photon Beam Position Monitors photon, synchrotron, synchrotron-radiation, monitoring 4239
  • S.F. Lin, H. Gao, P. Lu, B. Sun, J. Wang
    USTC/NSRL, Hefei, Anhui
  A log-ratio signal processing technique in photon beam position monitors (PBPM) was presented in this paper. The main performances (e.g. sensitivity, position offset and linearity range) of split PBPM and a pair of wires PBPM were analyzed , and the result of the measurement fit well with the theory. An inexpensive logarithmic amplifier chip which can measure photon currents from 0.1nA to 3.5mA was used in electronic circuits. The logarithmic ratio of the signal amplitudes from the PBPM provides a real-time analog signal that has wider linearity range and higher bandwidth than signal processing technique.

Supported by Natural Science Foundation of China (10275062) and CAS Knowledge Innovation Project (KY4206).

RPAT091 Longitudinal Electron Bunch Diagnostics Using Coherent Transition Radiation electron, 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 electron, undulator, photon, 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.  
RPAT100 Radiation-Hard Beam Position Detector for Use in the Accelerator Dump Lines target, electron, 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.

ROAD003 Post-Irradiation Properties of Candidate Materials for High-Power Targets proton, target, linac, booster 333
  • H.G. Kirk, H. Ludewig, L.F. Mausner, N. Simos, P. Thieberger
    BNL, Upton, Long Island, New York
  • Y. Hayato, K. Yoshimura
    KEK, Ibaraki
  • K.T. McDonald
    PU, Princeton, New Jersey
  • J. Sheppard
    SLAC, Menlo Park, California
  • L.P. Trung
    Stony Brook University, Stony Brook
  Funding: U.S. DOE.

The long term survivability of materials which can be used either for high-intensity targets or for the environment surrounding the target can be greatly influenced by how the physical properties of the material are altered by radiation damage. We have irradiated several candidate materials and report here on physical properties before and after irradiation.

RPPE002 Installation and Radiation Maintenance Scenario for J-PARC 50 GeV Synchrotron beam-losses, vacuum, shielding, extraction 835
  • M. Yoshioka, H. Kobayashi, T. Oogoe, Y. Takeuchi, Y. Watanabe
    KEK, Ibaraki
  • Y. Kuniyasu
    MELCO SC, Tsukuba
  • H. Oki, Y. Takiyama
  Funding: Ministry of Education, Culture, Science and Technology, Japan

J-PARC comprises a 400 MeV linac (181 MeV at the first stage), a 3 GeV rapid-cycling synchrotron and a 50 GeV synchrotron (Main Ring), which will provide high power proton beam to the material and life science facility, the neutrino facility and the nuclear and particle physics experimental hall. The installation of the accelerator components for the Main Ring will be started on mid. 2005 and the beam commissioning is scheduled in end of 2007. This paper describes the installation scenario of the accelerator components into the main ring tunnel and the development of radiation maintenance scenario for the beam injection and ejection systems.

RPPE007 High Precision Temperature Control and Analysis of RF Deionized Cooling Water System synchrotron, synchrotron-radiation, coupling, instrumentation 1057
  • Z.-D. Tsai, J.-C. Chang, C.-Y. Liu
    NSRRC, Hsinchu
  • J.-R. Chen
    NTHU, Hsinchu
  Previously, the Taiwan Light Source (TLS) has proven the good beam quality mainly depends on the utility system stability. A serial of efforts were devoted to these studies. Further, a high precision temperature control of the RF deionized cooling water system will be achieved to meet the more critical stability requirement. The paper investigates the mixing mechanism through thermal and flow analysis and verifies the practical influences. A flow mixing mechanism and control philosophy is studied and processed to optimize temperature variation which has been reduced from ±0.1? to ±0.01?. Also, the improvement of correlation between RF performance and water cooling stability will be presented.  
RPPE022 Machine Protection System for Concurrent Operation of RHIC and BLIP proton, controls, linac, monitoring 1754
  • M. Wilinski, S. Bellavia, J. Glenn, L.F. Mausner, K.L. Unger
    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.

The Brookhaven 200 MeV linac is a multipurpose machine used to inject low intensity polarized protons ultimately ending up in RHIC as well as to inject high intensity protons to BLIP, a medical isotope production facility. If high intensity protons were injected to RHIC by mistake, administrative radiation limits could be exceeded or sensitive electronics could be damaged. In the past, the changeover from polarized proton to high intensity proton operation has been a lengthy process, thereby never allowing the two programs to run simultaneously. To remedy this situation and allow for concurrent operation of RHIC and BLIP, an active interlock system has been designed to monitor current levels in the AGS using two current transformers with fail safe circuitry and associated electronics to inhibit beam to RHIC if high intensity is detected.

RPPE026 Operating Experience with Meson Production Targets at TRIUMF target, proton, alignment, beam-losses 1919
  • E.W. Blackmore, A.S. Dowling, R. Ruegg, M.C. Stenning
    TRIUMF, Vancouver
  High power targets are now required for operation at beam powers in excess of 1 MW for spallation neutron sources and neutrino factories. TRIUMF has been operating beryllium and graphite meson production targets for many years. Although the proton beam power of 100 kW at 500 MeV is lower, the beam densities and fluences are higher than most operating solid targets as other accelerators use rotating targets or larger beam spots. The beam size on the TRIUMF targets is maintained at 0.15 cm2 and this beam density leads to proton fluences of 1·1023 protons/cm2 per year. The beryllium targets are rectangular rods immersed in a water-cooled stainless steel jacket. The pyrolytic graphite targets consist of pie-shaped segments bonded to a water-cooled copper saddle. Operating experience shows that the graphite targets suffer thermal damage above beam currents of 120 uA but will operate for long periods at 100 uA. The beryllium targets can operate to 200 uA and appear to survive radiation damage beyond 10 dpa although some targets have failed due to structural damage. This paper will describe the operating experience with these targets and present some thermal and radiation calculations.  
RPPE031 Target and Horn Cooling for the Very Long Baseline Neutrino Experiment target, proton, focusing, simulation 2209
  • S. Bellavia, S.A. Kahn, H.G. Kirk, H. Ludewig, D. Raparia, N. Simos
    BNL, Upton, Long Island, New York
  Funding: This work is performed under the auspices of the US DOE.

Thermodynamic studies have been performed for the beam target and focusing horn system to be used in a very long baseline neutrino oscillation experiment. A 2mm rms beam spot with power deposition of over 18 KW presents challenging material and engineering solutions to this project. Given that the amount of heat transferred by radiation alone from the target to the horn is quite small, the primary mechanism is heat removal by forced convection in the annular space between the target and the horn. The key elements are the operating temperature of the target, the temperature of the cooling fluid and the heat generation rate in the volume of the target that needs to be removed. These working parameters establish the mass flow rate and velocity of the coolant necessary to remove the generated heat. Several cooling options were explored using a carbon-carbon target and aluminum horn. Detailed analysis, trade studies and simulations were performed for cooling the horn and target with gaseous helium as well as water.

RPPE036 Pressure Field Distribution in a Conical Tube with Transient and Outgassing Gas Sources vacuum, electron, 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.

RPPE037 The Vacuum System for PETRA III vacuum, dipole, synchrotron, undulator 2473
  • M. Seidel, R. Bospflug, J. Boster, W. Giesske, U. Naujoks, M. Schwartz
    DESY, Hamburg
  It is planned to rebuild the storage ringe PETRA II, presently used as pre-accelerator of HERA, into a high performance synchrotron light source. By making use of the large circumference and the installation of damping wigglers it will be possible to achieve exceptionally small emittances in the new storage ring. The requirements for the vacuum system are more advanced in the new storage ring as well. Besides the goal to achieve low pressures and fast conditioning times a major key for the new ring is a very high orbit stability which implies high thermal stability of BPM's and other vacuum components. We describe the basic concepts for chamber layout, pumping schemes, synchrotron radiation absorption and mechanical stability for the standard arcs and the experimental octant. Furthermore the expected performance will be discussed.  
RPPE043 Ultrathin Polyimide-Stainless Steel Heater for Vacuum System Bake-Out vacuum, insertion, synchrotron, simulation 2744
  • C. Rathjen, S. Blanchard, B. Henrist, K. Koelemeijer, B. Libera, P. Lutkiewicz
    CERN, Geneva
  Space constraints in several normal conducting magnets of the LHC required the development of a dedicated permanent heater for vacuum chamber bake-out. The new heater consists of stainless steel bands inside layers of polyimide. The overall heater thickness is about 0.3 mm. The low magnetic permeability is suitable for applications in magnetic fields. The material combination allows for temperatures high enough to activate a NEG coating. Fabrication is performed in consecutive steps of tape wrapping. Automation makes high volume production at low costs possible. About 800 m of warm vacuum system of the long straight sections of the LHC will be equipped with the new heater. This paper covers experience gained at CERN from studies up to industrialization.  
RPPE056 Status of the NSRL Storage Ring UHV System After Project-II vacuum, storage-ring, synchrotron, synchrotron-radiation 3334
  • Y. Wang, L. Fan, C. Y. Guan, D. M. Jiang, J. P. Wang, W. Wei, F. Y. Zhao
    USTC/NSRL, Hefei, Anhui
  The NSRL project-II has been finished in December 2004. The UHV system of storage ring has undergone improvement and now provide long beam lifetime and stable operations, the average pressure of ring is better than 2 × 10-8 Pascal without beam and 1 × 10-7 Pascal with beam, The typical beam lifetime is 12 hours at 300 mA and 800 MeV without wiggler and 8 hours at 300 mA and 800 MeV with wiggler on. The improvements and status of NSRL storage ring are described in this paper.  
RPPE064 Development of a Cryogenic Radiation Detector for Mapping Radio Frequency Superconducting Cavity Field Emissions shielding, radio-frequency, diagnostics 3627
  • D.W. Dotson, J. Mammosser
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by: U.S. DOE Contract No. DE-AC05-84er4015.

There is a relationship between field emissions in a Super Conducting RF cavity and the production of radiation (mostly X-rays). External (room temperature) detectors are shielded from the onset of low energy X-rays by the vacuum and cryogenic stainless steel module walls. An internal measuring system for mapping field emissions would assist scientists and engineers in perfecting surface deposition and acid washing module surfaces. Two measurement systems are undergoing cryogenic testing at JLab. One is an active CsI photodiode array and the second is an X-ray film camera. The CsI array has operated sucessfully in a cavity in liquid Helium but saturated at higher power due to scattering in the cavity. A shield with an aperature similar to the X-ray film detector is being designed for the next series of tests which will be completed before PAC-05.

RPPE065 Beam Loss Ion Chamber System Upgrade for Experimental Halls ion, target, beam-losses, monitoring 3650
  • D.W. Dotson, D.J. Seidman
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by: U.S. DOE Contract No DE-AC05-84ER4015.

The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic "burn through." Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an "off the shelf" Programmable Logic Controller located in a single controll box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage "Brick" at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time.

RPPP012 Collective Effects in the CLIC Damping Rings wiggler, damping, ion, emittance 1312
  • F. Zimmermann, M. Korostelev, D. Schulte
    CERN, Geneva
  • T.A. Agoh, K. Yokoya
    KEK, Ibaraki
  The small emittance, short bunch length, and high current in the CLIC damping ring could give rise to collective effects which degrade the quality of the extracted beam. In this paper, we survey a number of possible instabilities and estimate their impact on the ring performance. The effects considered include fast beam-ion instability, coherent synchrotron radiation, and electron cloud, in addition to conventional single and multi-bunch instabilities.  
RPPP015 Reconstruction of IP Beam Parameters at the ILC from Beamstraahlung photon, simulation, luminosity, electron 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.

RPPP020 Linear Damping Systems for the International Linear Collider damping, wiggler, emittance, positron 1689
  • G. Dugan
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  Funding: Supported by the National Science Foundation

The International Linear Collider requires very low transverse emittance beams in order to realize the specified high luminosity. These beams are conventionally produced using radiation damping in specially designed damping rings. A linear damping system, consisting of alternating wigglers and accelerating structures arranged in a straight line, can be considered to replace, or to augment, conventional damping rings. In this paper, the basic features, feasibility, advantages, and disadvantages, of such systems, as applied to the International Linear Collider, will be discussed.

RPPP048 Beam Collimation and Machine-Detector Interface at the International Linear Collider photon, collimation, synchrotron, synchrotron-radiation 2995
  • N.V. Mokhov, A.I. Drozhdin, M.A. Kostin
    Fermilab, Batavia, Illinois
  Funding: Work supported by the Universities Research Association, Inc., under contract DE-AC02-76CH03000 with the U.S. Department of Energy.

Synchrotron radiation, spray from the dumps and extraction lines, beam-gas and beam halo interactions with collimators and other components in the ILC beam delivery system create fluxes of muons and other secondaries which can exceed the tolerable levels at a detector by a few orders of magnitude. It is shown that with a multi-stage collimation system, magnetized iron spoilers which fill the tunnel and a set of masks in the detector, one can hopefully meet the design goals. Results of modeling with the STRUCT and MARS15 codes of beam loss and energy deposition effects are presented in this paper. We concentrate on collimation system and mask design and optimization, short- and long-term survivability of the critical components (spoilers, absorbers, magnets, separators, dumps), dynamic heat loads and radiation levels in magnets and other components, machine-related backgrounds and damage in collider detectors, and environmental aspects (prompt dose, ground-water and air activation).

RPPP053 Simulations of Resistive-Wall Instability in the ILC Damping Rings damping, feedback, simulation, pick-up 3241
  • A. Wolski, D.A. Bates, J.M. Byrd
    LBNL, Berkeley, California
  Funding: Work supported by U.S. Department of Energy, Director, Office of Science, Contract No. DE-AC03-76SF00098.

Options being considered for the ILC Damping Rings include lattices with circumferences up to 17 km. The circumference, beam current and beam energy place the damping rings in a regime where resistive-wall instability is a concern, particularly as there are very demanding tolerances on the bunch-to-bunch jitter. Generally, it is possible to make good analytical estimates of the coupled-bunch growth rates in a storage ring, but particular features of the damping rings (including the fill pattern, large variations of the lattice functions and beam-pipe cross-section in different parts of the ring, and transverse beam coupling in the long straight sections) make it desirable to study the coupled-bunch instabilities using simulations. Here, we present the results of simulations of the transverse instabilities using a detailed lattice model. A bunch-by-bunch feedback system will be needed to suppress the instabilities, and a model for an appropriate feedback system is included in the simulations.

RPPT002 Harmonic Content of the BESSY FEL Radiation undulator, bunching, electron, 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, electron 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, linac, emittance, electron 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.

RPPT021 Inducing Strong Density Modulation with Small Energy Dispersion in Particle Beams and the Harmonic Amplifier Free Electron Laser electron, 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.

RPPT028 Free Electron Lasers with Slowly Varying Beam and Undulator Parameters undulator, electron, vacuum, 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 electron, 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.  
RPPT033 Potential Use of eRHIC’s 10-to-20 GeV ERL for FELs and Light Sources electron, 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, electron, photon, 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, electron, vacuum, simulation 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.

RPPT037 Technique for the Generation of Attosecond X-Ray Pulses Using an FEL laser, electron, undulator, 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.

RPPT040 Weak FEL Gain Detection with a Modulated Laser-Based Beam Heater undulator, laser, electron, 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.  
RPPT060 The MuCool Test Area at Fermilab linac, proton, shielding, target 3482
  • C. Johnstone, A. Bross, I. Rakhno
    Fermilab, Batavia, Illinois
  Funding: Work supported by the US Dept. of Energy under contract No. DE-AC02-76CH03000

A new experimental area designed to develop, test and verify muon ionization cooling using the 400- MeV Fermilab Linac proton beam began construction in spring, 2002. This area will be used initially for cryogenic tests of liquid-hydrogen absorbers for the MUCOOL R&D program and, later, for high-power beam tests of these absorbers and other prototype muon-cooling apparatus. The experimental scenarios being developed for muon facilities involve collection, capture, and cooling of large-emittance, high-intensity muon beams–~1013 muons at a repetition rate of 15Hz, so that conclusive tests of the apparatus require full Linac beam, or 1.6 x 1013 p at 15 Hz. To support the muon cooling facility, a new primary beamline will divert beam from the Linac to the test facility. Located southwest of Wilson Hall between the Linac berm and parking lot, implementation of the facility and associated beamline takes advantage of civil construction and resources that remain from the 400-MeV Linac Upgrade Project. The design concept for the MuCool facility is taken from an earlier proposal, but modifications to the existing proposal were necessary to accommodate high-intensity beam, cryogenics, and the increased scale of the cooling experiments.

RPPT062 Radiation Simulations for the Proposed ISOL Stations for RIA target, shielding, simulation, ion 3561
  • R.M. Ronningen, V. Blideanu, G. Bollen, D. Lawton, P.F. Mantica, D.J. Morrissey, B. Sherrill, A. Zeller
    NSCL, East Lansing, Michigan
  • L. Ahle, J.L. Boles, S. Reyes, W. Stein
    LLNL, Livermore, California
  • J.R. Beene, W. Burgess, H.K. Carter, D.L. Conner, T.A. Gabriel, L.K. Mansur, R. Remec, M.J. Rennich, D.W. Stracener, M. Wendel
    ORNL, Oak Ridge, Tennessee
  • T.A. Bredeweg, F.M. Nortier, D.J. Vieira
    LANL, Los Alamos, New Mexico
  • P. Bricault
    TRIUMF, Vancouver
  • L.H. Heilbronn
    LBNL, Berkeley, California
  Funding: This work is supported in part by Michigan State University, the U.S. Department of Energy, and the National Research Council of Canada.

The Department of Energy's Office of Nuclear Physics, within the Office of Science (SC), has given high priority to consider and analyze design concepts for the target areas for the production of rare isotopes via the ISOL technique at the Rare-Isotope Accelerator (RIA) Facility. Key criteria are the maximum primary beam power of 400 kW, minimizing target change-out time, good radiological protection, flexibility with respect to implementing new target concepts, and the analysis and minimization of hazards associated with the operation of the facility. We will present examples of on-going work on simulations of radiation heating of targets, surrounding components and shielding, component activation, and levels of radiation dose, using the simulation codes MARS, MCNPX, and PHITS. These results are important to make decisions that may have a major impact on the layout, operational efficiency and cost of the facility, hazard analysis, shielding design, civil construction, component design, and material selection, overall layout, and remote handling concepts.

RPPT063 Radiation Simulations and Development of Concepts for High Power Beam Dumps, Catchers and Pre-separator Area Layouts for the Fragment Separators for RIA simulation, target, quadrupole, ion 3594
  • R.M. Ronningen, V. Blideanu, G. Bollen, D. Lawton, D.J. Morrissey, B. Sherrill, A. Zeller
    NSCL, East Lansing, Michigan
  • L. Ahle, J.L. Boles, S. Reyes, W. Stein, A. Stoyer
    LLNL, Livermore, California
  • J.R. Beene, W. Burgess, H.K. Carter, D.L. Conner, T.A. Gabriel, L.K. Mansur, R. Remec, M.J. Rennich, D.W. Stracener, M. Wendel
    ORNL, Oak Ridge, Tennessee
  • H. Geissel, H. Iwase
    GSI, Darmstadt
  • I.C. Gomes, F. Levand, Y. Momozaki, J.A. Nolen, B. Reed
    ANL, Argonne, Illinois
  • L.H. Heilbronn
    LBNL, Berkeley, California
  Funding: This work is supported in part by Michigan State University, the US DOE, and the Gesellschaft für Schwerionenforschung, Germany.

The development of high-power beam dumps and catchers, and pre-separator layouts for proposed fragment separators of the Rare-Isotope Accelerator (RIA) facility are important in realizing how to handle the 400 kW in the primary beam. We will present examples of pre-conceptual designs of beam dumps, fragment catchers, and the pre-separator layout. We will also present examples of ongoing work on radiation simulations using the heavy-ion-transport code PHITS, characterizing the secondary radiation produced by the high-power ion beams interacting with these devices. Results on radiation heating of targets, magnet coils, associated hardware and shielding, component activation, and levels of radiation dose will be presented. These initial studies will yield insight into the impact of the high-power dissipation on fragment separator design, remote handling concepts, nuclear safety and potential facility hazard classification, shielding design, civil construction design, component design, and material choices. Furthermore, they will provide guidance on detailed radiation analyses as designs mature.

RPPT066 Electromigration Issues in High Current Horn target, electron, secondary-beams, 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 electron, cathode, linac, acceleration 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 electron, 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.

FPAE010 Barrier RF System and Applications in Main Injector booster, proton, injection, emittance 1189
  • W. Chou, D. Wildman
    Fermilab, Batavia, Illinois
  • A. Takagi
    KEK, Ibaraki
  • H. Zheng
    CALTECH, Pasadena, California
  Funding: Work supported by the Universities Research Association, INC. under contract with the U.S. Department of Energy NO. DE-AC02-76CH03000 and by the US-Japan Collaboration in High Energy Physics.

A wideband RF system (the barrier RF) has been built and installed in the Fermilab Main Injector. The cavities are made of low Q Finemet cores. The modulators use high voltage fast solid-state switches. It can generate ±7 kV single square voltage pulses. It is used to stack two proton batches to double the bunch intensity for pbar production. The stacked high intensity beams have been successfully accelerated to 120 GeV with small losses. A new test to continuously stack 12 batches for the NuMI experiment is under way.

FPAE011 8 GeV H- Ions: Transport and Injection electron, 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.

FPAE075 Radiation Damage to the Elements of the SIS300 Dipoles ion, dipole, extraction, simulation 3943
  • E. Mustafin, J. Kaugerts, G. Moritz, G. Walter
    GSI, Darmstadt
  • L.N. Latysheva, N. Sobolevskiy
    RAS/INR, Moscow
  Funding: Supported by the grant of the GSI-INTAS Project #03-54-3588.

Radiation damage to various elements of the cosine-theta type dipoles of the SIS300 synchrotron of the FAIR Project was calculated. Among the elements under consideration were the superconducting cable, insulating materials, and high-current by-pass protection diodes. The Monte-Carlo particle transport codes MARS and SHIELD were used to simulate propagation of the lost ions and protons, together with the products of nuclear interactions in the material of the elements. It was found that the lifetime of the protection diodes under irradiation is a more restrictive limit for the tolerable level of beam losses than the occurrence of magnet quenches.

FPAP002 Experimental Determination of E-Cloud Simulation Input Parameters for DAFNE electron, photon, simulation, vacuum 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.  
FPAT032 NuMI Proton Kicker Extraction Magnet Termination Resistor System kicker, impedance, extraction, proton 2224
  • S.R. Reeves, C.C. Jensen
    Fermilab, Batavia, Illinois
  Funding: Fermilab is operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the U.S. Department of Energy.

The temperature stability of the kicker magnet termination resistor assembly directly affects the field flatness and amplitude stability of the kick. Comprehensive thermal enhancements were made to the existing Main Injector resistor assembly design to satisfy NuMI performance specifications. Additionally, a fluid-processing system utilizing Fluorinert® FC-77 high-voltage dielectric was built to precisely control the setpoint temperature of the resistor assembly from 70 to 120F, required to maintain constant resistance during changing operational modes. The Fluorinert® must be continually processed to remove hazardous breakdown products caused by radiation exposure to prevent chemical attack of system components. Design details of the termination resistor assembly and Fluorinert® processing system are described. Early performance results will be presented.

FPAT041 Design and Simulation of an Anode Stalk Support Insulator simulation, vacuum, alignment, power-supply 2663
  • L. Wang, T.L. Houck, G.A. Westenskow
    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 No. W-7405-Eng-48.

An anode stalk support insulator in a magnetically insulated transmission line was designed and modeled. One of the important design criteria is that within space constraints, the electric field along the insulator surface has to be minimized in order to prevent a surface flashover. In order to further reduce the field on the insulator surface, metal rings between insulator layers were also specially shaped. To facilitate the design process, electric field simulations were performed to determine the maximum field stress on the insulator surfaces and the transmission line chamber.

FPAT045 Upgrade of the ESRF Vacuum Control System vacuum, monitoring, storage-ring, diagnostics 2857
  • D. Schmied, E. Burtin, P. Guerin, M. Hahn, R. Kersevan
    ESRF, Grenoble
  The temperature acquisition as well as the whole vacuum control system of the electron storage ring of the ESRF is in operation since more than ten years now. Apart from difficulties to have appropriate support for the old systems we start facing problems of aging and obsolescence. We have been reviewing our philosophy of data acquisition and remote control in order to update our systems with state of the art technology, taking into account our operational experience. We have started installing shielded “intelligent” devices inside the storage ring tunnel taking benefit from the availability of ethernet connections. Like this we can take advantage of the latest developments linked to these technologies, such as OPC Server, Webpage instrument control, and more.  
FPAT055 The Radiation Safety Interlock System for Top-Up Mode Operation at NSRRC injection, synchrotron, booster, storage-ring 3328
  • C.R. Chen, F.D. Chang, S.-P. Kao, Joseph. Liu, R.J. Sheu, J.P. Wang
    NSRRC, Hsinchu
  The radiation safety interlock systems of NSRRC have been operated for more than a decade. Some modification actions have been implemented in the past to perfect the safe operation. The machine and its interlock system were originally designed to operate at the decay mode. Recently some improvement programs to make the machine injection from original decay mode to top-up mode at NSRRC has initiated. For users at experimental area the radiation dose resulted from top-up re-fill injections where safety shutters of beam-lines are opened will dominate. In addition to radiation safety action plans such as upgrading the shielding, enlarging the exclusion zones and improving the injection efficiency, the interlock system for top-up operation is the most important to make sure that injection efficiency is acceptable. To ensure the personnel radiation safety during the top-up mode, the safety interlock upgrade and action plans will be implemented. This paper will summarize the original design logic of the safety interlock system. Historical modification actions for this system will be mentioned. New design logic to ensure radiation safety for top-up mode operation will be discussed.  
FPAT059 Event Driven Automatic State Modification of BNL's Booster for NASA Space Radiation Laboratory Solor Particle Simulator booster, optics, ion, extraction 3447
  • K.A. Brown, S. Binello, M. Harvey, J. Morris, A. Rusek, N. Tsoupas
    BNL, Upton, Long Island, New York
  Funding: Work performed under Contract #DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy.

The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. NASA is interested in reproducing the energy spectrum from a solar flare in the space environment for a single ion species. To do this we have built and tested a set of software tools which allow the state of the Booster and the NSRL beam line to be changed automatically. In this report we will desribe the system and present results of beam tests.

FOAA010 Full Characterization at Low Temperature of Piezoelectric Actuators Used for SRF Cavities Active Tuning vacuum, linac, proton, electromagnetic-fields 728
  • M. Fouaidy, S. Blivet, F. Chatelet, N. Hammoudi, G.M. Martinet, A. Olivier, H. Saugnac
    IPN, Orsay
  Funding: EU, CNRS-IN2P3.

In the frame of the CARE project activities, supported by EU, IPN Orsay participate to the development of a fast cold tuning system for SRF cavities operating at a temperature T=2 K. The study is aimed at full characterization of piezoelectric actuators at low temperature. A new experimental facility was developed for testing various prototypes piezoelectric actuators and successfully operated for T in the range 1.8 K-300 K. Different parameters were investigated as function of T: piezoelectric actuator displacement vs. applied voltage V, capacitance vs. T, dielectric and thermal properties vs. T and finally heating DT due to dielectric losses vs. modulating voltage Vmod and frequency. We observed a decrease of the Full Range Displacement (FRD or DX) of the actuator from ~40μm @ 300K down to 1.8μm-3μm @ 1.8K, depending on both material and fabrication process of the piezostacks. Besides, both material and fabrication process have a strong influence on the shape of the characteristics DX vs. T dependence. Moreover, the variations of losses tangent with T show a maximum at T in the range 30 K-120 K. Finally a dedicated facility located at CERI (Orléans, France) for radiation hardness tests of actuators with fast neutrons at T=4.2 K was developed and the first beam tests results are summarized.

FOAB002 Advances in X-Band and S-Band Linear Accelerators for Security, NDT, and Other Applications linac, electron, 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.