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Müller, W.F.O.

Paper Title Page
WEPCH112 Database Extension for the Beam Dynamics Simulation Tool V-code 2176
 
  • W. Ackermann, W.F.O. Müller, B. Steiner, T. Weiland
    TEMF, Darmstadt
  • J. Enders, H.-D. Gräf, A. Richter
    TU Darmstadt, Darmstadt
 
  The beam dynamics simulation tool V-Code has been proved to be very useful in redesigning the injector layout at the superconducting linear accelerator in Darmstadt (S-DALINAC). Modifications in the beam optics are necessary because a new source of polarized electrons should be installed in addition to the existing thermionic gun. The calculations are performed with V-Code which is designed to handle a large amount of individual beam line elements and can therefore be used for extensive accelerator studies. The available database includes all the necessary components like solenoids, quadrupoles and rf cavities, but as a result of their consecutive treatment overlapping external fields are not allowed. Due to geometrical restrictions in the assembly of the new source a space-saving candidate of a quadrupole triplet violates this software-related condition if it is regarded as three distinct quadrupoles. Consequently, a more general beam line element has to be created which treats the lenses as a single unit without interference of their fields to attached cells. The indispensable data base extension together with simulation results and implementation verifications will be presented.  
WEPCH115 Numerical Simulation and Optimization of a 3-GHz Chopper/Prebuncher System for the S-DALINAC 2185
 
  • N. Somjit, W.F.O. Müller, T. Weiland
    TEMF, Darmstadt
  • R. Eichhorn, J. Enders, H.-D. Gräf, C. Heßler, Y. Poltoratska, A. Richter
    TU Darmstadt, Darmstadt
 
  A new source of polarized electrons with an energy of 100 keV is presently being developed at the superconducting Darmstadt electron linear accelerator S-DALINAC for future nuclear- and radiation-physics experiments. The pulsed electron beam emitted by the photocathode will be cut to 50 ps by a chopper operated at 3 GHz, and further bunch compression down to 5 ps will be achieved by a two-stage prebuncher section. The chopper-prebuncher system is based on similar devices used at the Mainz Mikrotron (MAMI) where the accelerator frequency is slightly smaller (2.4 GHz). For the chopper, a cylindrical resonator operating at TM110 mode is selected to deflect the electron beam onto an ellipse, i.e., both horizontally and vertically. This is simply achieved by particular slits on both ends of the resonator. The prebunching system consists of two cavities. For increasing the longitudinal capture efficiency, the first cavity will be operated at the fundamental accelerator frequency of the S-DALINAC of 3 GHz, and the second cavity at 6 GHz. The cavities are designed to work at the TM010 mode and TM020 mode for the fundamental and first harmonic, respectively.  
WEPCH116 Recent Simulation Results of the Polarized Electron Injector (SPIN) of the S-DALINAC 2188
 
  • B. Steiner, W.F.O. Müller, T. Weiland
    TEMF, Darmstadt
  • J. Enders, H.-D. Gräf, C. Heßler, G. Iancu, A. Richter, M. Roth
    TU Darmstadt, Darmstadt
 
  Recent design and development for a polarized electron source (SPIN) for the recirculating superconducting electron linear accelerator S-DALINAC will be presented. The polarized electron beam will be produced by photoemission from an InAlGaAs/GaAs superlattice cathode and will be accelerated to 100 kV electrostatically. The results of the beam dynamics simulation will be shown in detail. The start phase space of the electron bunch behind the gun has been approximated. The transverse focusing system consists of very short quadrupoles. Further main components of the new injector are a Wien filter, a Mott polarimeter, a chopper-prebuncher system (based on devices used at the Mainz Mikrotron MAMI), and diverse beam diagnostic tools. For the approximation of the start phase space CST MAFIA is used, and for the beam dynamic simulation VCode is used.  
MOPLS066 Direct Measurement of Geometric and Resistive Wakefields in Tapered Collimators for the International Linear Collider 697
 
  • N.K. Watson, D. Adey, M.C. Stockton
    Birmingham University, Birmingham
  • D.A.-K. Angal-Kalinin, C.D. Beard, J.L. Fernandez-Hernando, F. Jackson
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R. Arnold, R.A. Erickson, C. Hast, T.W. Markiewicz, S. Molloy, M.C. Ross, S. Seletskiy, A. Seryi, Z. Szalata, P. Tenenbaum, M. Woodley, M. Woods
    SLAC, Menlo Park, California
  • R.J. Barlow, A. Bungau, R.M. Jones, G.Yu. Kourevlev, A. Mercer
    UMAN, Manchester
  • D.A. Burton, J.D.A. Smith, A. Sopczak, R. Tucker
    Lancaster University, Lancaster
  • C. Densham, G. Ellwood, R.J.S. Greenhalgh, J. O'Dell
    CCLRC/RAL, Chilton, Didcot, Oxon
  • Y.K. Kolomensky
    UCB, Berkeley, California
  • M. Kärkkäinen, W.F.O. Müller, T. Weiland
    TEMF, Darmstadt
  • N. Shales
    Microwave Research Group, Lancaster University, Lancaster
  • M. Slater
    University of Cambridge, Cambridge
  • I. Zagorodnov
    DESY, Hamburg
  • F. Zimmermann
    CERN, Geneva
 
  Precise collimation of the beam halo is required in the ILC to prevent beam losses near the interaction region that could cause unacceptable backgrounds for the physics detector. The necessarily small apertures of the collimators lead to transverse wakefields that may result in beam deflections and increased emittance. A set of collimator wakefield measurements has previously been performed in the ASSET region of the SLAC LINAC. We report on the next phase of this programme, which is carried out at the recently commissioned End Station A test facility at SLAC. Measurements of resistive and geometric wakefields using tapered collimators are compared with model predictions from MAFIA and GdfidL and with analytic calculations.  
THPCH161 Status of the Polarized Electron Gun at the S-DALINAC 3173
 
  • C. Heßler, M. Brunken, J. Enders, H.-D. Gräf, G. Iancu, Y. Poltoratska, M. Roth
    TU Darmstadt, Darmstadt
  • W. Ackermann, W.F.O. Müller, N. Somjit, B. Steiner, T. Weiland
    TEMF, Darmstadt
  • K. Aulenbacher
    IKP, Mainz
 
  Aiming at an extension of the experimenting capabilities for nuclear structure physics at low momentum transfer at the superconducting Darmstadt electron linear accelerator S-DALINAC, a polarized electron gun is being constructed. The new injector will be able to supply the S-DALINAC with 100 keV polarized electrons and should complement the present, unpolarized thermionic source. The design requirements are a degree of polarization of at least 80%, a mean current intensity of 0.06 mA and a 3 GHz cw structure. The basic design of the gun was adapted from the source of polarized electrons at MAMI, Mainz*, and optimized in various simulations. The active material is a strained layer GaAs crystal which is exposed to an 830 nm pulsed laser beam. We report on the status of the polarized source, the preparation setup and a test beam line.

*K. Aulenbacher et al., Nucl. Instrum. Meth. A 391, 498 (1997).