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MOBP01 ISIS Upgrades – A Status Report target, proton, linac, rfq 20
 
  • D. J.S. Findlay
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  Since 2002 several accelerator upgrades have been made to the ISIS spallation neutron source at the Rutherford Appleton Laboratory in the UK, and upgrades are currently continuing in the form of the Second Target Station Project. The paper will review the upgrade processes, and will also look forward to possible future schemes at ISIS beyond the Second Target Station.  
 
MOBP02 FAIR at GSI ion, antiproton, storage-ring, heavy-ion 24
 
  • P. J. Spiller
    GSI, Darmstadt
  A new faciliy for antiproton and ion research (FAIR) is being planned and prepared to be built at GSI, Germany. R&D and prototype design is presently conducted at GSI and several other institutes worldwide, representing the future FAIR member states. Furthermore a major upgrade program for the running GSI accelerators, the heavy ion linac UNILAC and the heavy ion synchrotron SIS18 has been started. In parallel, the plannings for buildings and tunnels and the permit procedure for construction were launched. The new facility will consist of a two stage heavy ion synchrotron SIS100/300 for the generation of intense heavy ion and proton beams. These beams can be delivered wether as short compressed bunches for the production of secondary beams with subsequent processing in storage rings or as slow extracted beams with high duty cycle for fixed target experiments. The quality and intensity of the produced secondary beams (rare isotope and antiproton beams) will be significantly improved in a number of storage rings used for stacking, beam cooling and for internal target experiments.  
 
TUAX03 Beam loss, emittance growth and halo formation due to the pinched electron cloud electron, emittance, simulation, resonance 84
 
  • E. Benedetto, F. Zimmermann
    CERN, Geneva
  • G. Franchetti
    GSI, Darmstadt
  • K. Ohmi
    KEK, Ibaraki
  Electron cloud can cause beam losses and emittance growth in proton or positron storage rings. If the electron density exceeds a certain threshold value, a strong head-tail instability manifests itself, characterized by a rapid beam-size blow-up with a rise time comparable to the synchrotron period. However, even for densities below the coherent-instability threshold, the electron-cloud can give rise to a significant emittance growth. We identified the mechanism for this incoherent growth as one caused by the combined effect of the beam particles synchrotron motion and the longitudinal variation of the tune shift, which is proportional to the pinched electron-cloud distribution along the bunch. This can give rise to the periodic crossing of a resonance, in analogy to halo formation in space-charge dominated beams, or eventually, if the tune shift is sufficiently large, to the crossing of bunch regions where the single-particle motion is linearly unstable.  
 
TUAY01 Overview of proton driver studies for neutrino and muon factories proton, linac, factory, target 64
 
  • W. Chou
    Fermilab, Batavia, Illinois
  There are a number of proton driver studies around the world: SPL at CERN, an 8 GeV SCRF linac at Fermilab, AGS upgrade at BNL, Proton Driver for the International Scoping Study on Neutrino Factories and Superbeams, FFAG based proton driver in Japan, etc. This talk will give an overview of them and compare their similarities and differences. Common R&D projects and possible inter-laboratory collaborations will be discussed.  
 
TUAZ01 Overview of recent halo diagnosis and non-destructive beam profile monitoring electron, laser, diagnostics, radiation 54
 
  • K. Wittenburg
    DESY, Hamburg
  Beam profile (emittance) and beam halo are characteristic properties of high-intensity and high energy beams that might limit the performance of the adjacent accelerator. Therefore a reliable measurement and determination of these parameters is most helpful for understanding, tuning and improvement of the whole accelerator chain to achieve the best (at least the design-) performance. This talk will give an overview over recent instruments used for non-destructive beam profile and halo monitoring and will discuss their limits, experiences and latest improvements.  
 
TUBX01 Impedance and radiation generated by a ceramic chamber with RF shields and TiN coating impedance, space-charge, electromagnetic-fields, extraction 125
 
  • Y. H. Chin, S. Lee, K. Takata, T. Toyama
    KEK, Ibaraki
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Tsutsui
    SHI, Tokyo
  In the RCS (Rapid Cycle Synchrotron) ring of J-PARC, we use ceramic chambers with the interior TiN coating and exterior Cu RF shields in the magnet sections. A new theory has been developed for calculation of impedance in this unusual configuration. When it was applied to a prototype RCS ceramic chamber, the calculation results got good agreement with the measurement results. We also considered the dipole radiation from gaps between Cu shields of the ceramic chamber in the bending magnets. The effects turn out to be rather small thanks to the special configuration of the ceramic chambers. We measured the radiation from a ceramic break with and without RF shields and capacitors in the KEK, PS and found that the RF shields with capacitors considerably suppress the radiation from the ceramic break. We summarize all these studies in this paper.  
 
TUBX03 Coupling impedance of the J-PARC kicker magnets kicker, impedance, extraction, coupling 140
 
  • T. Toyama, Y. Hashimoto, E. Nakamura, Y. Shirakabe
    KEK, Ibaraki
  • J. Kamiya, Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  The single- and twin-wire measurements both for the longitudinal ( ZL ) and transverse impedances ( ZT ) will be discussed for the J-PARC kicker magnets: a lumped circuit kicker and several types of traveling wave kickers. The question if a position shifted single-wire can measure ZT is discussed. The measurement results are compared with the equivalent circuit analysis. The relation between the imaginary part of the impedance and causality will also be discussed.  
 
TUBX05 Cures for beam instabilities in the CERN SPS and their limitations emittance, beam-loading, feedback, injection 153
 
  • E. N. Shaposhnikova
    CERN, Geneva
  The LHC beam in the SPS is unstable with a threshold almost an order of magnitude below the nominal intensity. The cures used to stabilise this beam against coupled bunch instabilities apart from beam feedback, feed-forward and longitudinal damping, include a fourth harmonic RF system and controlled emittance blow-up. The limitations of the two last methods were studied experimentally and are analysed here from the point of view of beam quality requirements at extraction and future intensity increases up to ultimate value.  
 
WEAX01 Resonance trapping due to space charge and synchrotron motion, in theory, simulations, and experiments beam-losses, resonance, emittance, space-charge 167
 
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt
  With the development of high intensity accelerator, the role of space charge effect in a nonlinear lattice gained special attention, as in the FAIR project at GSI, where long term storage of high intensity beams is required. The simultaneous presence of space charge and a nonlinear lattice creates an unprecedented challenge for ring designers as well as a new area of studies in beam physics. We present our understanding of the effect of space charge and chromaticity on the nonlinear beam dynamics of a bunched beam.  
 
WEBZ01 Correction of unevenness in Recycler beam profile feedback, beam-loading, impedance, proton 244
 
  • K. Y. Ng, J. L. Crisp, M. Hu
    Fermilab, Batavia, Illinois
  When a beam is confined between two rf barriers in the Fermilab Recycler Ring, it is observed that the longitudinal beam profile between the barriers is in general very uneven (typically about 20% for a beam of intensity 5E11). This leads to the consequence that the momentum-mined antiproton bunches may have an intolerable variation in bunch intensity. It is shown that the observed unevenness in beam profile is the result of a tiny amount (around 2%) of rf potential imperfection and a tiny amount (around 0.5%) of rf beam loading. The beam profile can be made even by feeding back the unevenness of the effective rf potential to the low-level rf.  
 
THAY06 Fast-Pulsed Superconducting Magnets dipole, ion, antiproton, quadrupole 324
 
  • C. Muehle
    GSI, Darmstadt
  Up to now only one synchrotron (Nuclotron at JINR, Dubna) has been equipped with fast-pulsed superconducting magnets. The demand for high beam intensities leads to the requirement of fast-pulsed, periodically cycling magnets for synchrotrons and fast-pulsed magnets for storage rings. An example is FAIR (Facility for Antiproton and Ion Research) at GSI, which will consist of two synchrotrons in one tunnel and several storage rings. The fast field ramp rate and repetition frequency introduce many magnet design problems and constraints in the operation of the accelerator. Persistent currents in the superconductor and eddy currents in wire, cable, iron and vacuum chamber reduce the field quality and generate cryogenic losses. A magnet lifetime of 20 years is anticipated, resulting in up to 108 magnet cycles. Therefore special attention has to be paid to magnet material fatigue problems. R&D work is being done in collaboration with many institutions, to reach the requirements mentioned above. Model dipoles were built and tested. The results of the R&D are reported. The advantages of the use of low field, fast pulsed superconducting, compared to resistive, magnets will be discussed.  
 
THBW01 Code benchmarking on induce space charge particle trapping space-charge, emittance, resonance, sextupole 344
 
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt
  • S. Machida
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  Trapping of particles in a high intensity bunch has been studied by using the MICROMAP. The numerical studies were used to interpret the CERN-PS experiments and explore the underlying beam loss/emittance growth mechanisms. We present in this contributed talk the first attempt of code benchmarking in modeling the long term storage of a high intensity bunch. The code benchmarking is initiated between MICROMAP and SIMPSONS.  
 
THCX02 Cost Comparison of Linear and Circular Accelerators acceleration, linac, RF-structure, factory 356
 
  • A. G. Ruggiero
    BNL, Upton, Long Island, New York
  A simple comparison of construction cost between a Linear and a Circular Accelerator is made. Two simplified models are proposed and studied. The comparison is made with the two major magnet and RF cavity components. An approximated criterion is found according to which the Circular Accelerator is indeed the more economical of the two provided that the beam circulates a minimum number of turns.  
 
FRAP07 Summary of Working Group F ion, laser, acceleration, proton 375
 
  • S. R. Koscielniak
    TRIUMF, Vancouver