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

positron

Paper Title Other Keywords Page
MOPP008 Design of the Photon Collimators for the ILC Positron Helical Undulator photon, undulator, vacuum, electron 565
 
  • A. Bungau
    UMAN, Manchester
  • I. R. Bailey, J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva
    Liverpool University, Science Faculty, Liverpool
  • E. Baynham, T. W. Bradshaw, F. S. Carr, J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A. J. Brummitt, A. J. Lintern
    STFC/RAL, Chilton, Didcot, Oxon
  • J. A. Clarke, O. B. Malyshev, N. C. Ryder, D. J. Scott
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • N. A. Collomb
    STFC/DL, Daresbury, Warrington, Cheshire
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  • S. Hesselbach, G. A. Moortgat-Pick
    Durham University, Durham
  • L. Zang
    Cockcroft Institute, Warrington, Cheshire
  A number of photon collimators are placed inside the helical undulator to protect the cold surfaces of the vacuum vessel from being hit by the photons and thus achieving the baseline pressure requirement. Computer simulations were run in order to determine the energy deposition and instantaneous temperature rise in these collimators and various material candidates were studied. This paper presents the status of the simulation.  
 
MOPP023 Test of Short Period SC Undulator undulator, electron, vacuum, radiation 595
 
  • A. A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  We represent details of design and results of test of 4-m long undulator in cryostat having period 12mm and aperture ~6.35 mm allowing K=1.0. This undulator can be used in ILC positron conversion system as well as insertion device for developing FEL systems.  
 
MOPP024 Depolarization and Beam-beam Effects at the Linear Collider polarization, photon, background, linear-collider 598
 
  • G. A. Moortgat-Pick, S. Hesselbach
    Durham University, Durham
  • I. R. Bailey, G. A. Moortgat-Pick, B. J.A. Shepherd
    Cockcroft Institute, Warrington, Cheshire
  • D. P. Barber
    DESY, Hamburg
  • E. Baynham, T. W. Bradshaw, F. S. Carr, J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A. J. Brummitt, A. J. Lintern
    STFC/RAL, Chilton, Didcot, Oxon
  • A. Bungau
    UMAN, Manchester
  • J. A. Clarke, O. B. Malyshev, N. C. Ryder, D. J. Scott
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva, L. Zang
    Liverpool University, Science Faculty, Liverpool
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  The clean environment at the interaction point of a lepton linear collider allows high-precision measurements for physics analyses. In order to exploit this potential, precise knowledge about the polarization state of the beams is also required. In this paper we concentrate on depolarization effects caused by the intense beam-beam interaction, which is expected to be the dominant source of depolarization. Higher-order effects, as well as critical analyses of the theoretical assumptions used in the past and theoretical improvements in the derivation of suitable equations, are given. Updates on existing simulation programs are reported. Numerical results for the design of the International Linear Collider (ILC) are discussed.  
 
MOPP046 Collimation Optimizations, Capture Efficiency, and Primary-Beam Power Loss in the ILC Positron Source target, collimation, optics, injection 649
 
  • F. Zhou, Y. Nosochkov, J. Sheppard
    SLAC, Menlo Park, California
  • W. Liu
    ANL, Argonne, Illinois
  The ILC positron beam generated from a thin Ti target has a wide energy spread and large transverse divergence. With the collection optics immediately downstream of the target and pre-acceleration to 125 MeV, the collected positron beam still has a long tail of positrons with low energies and large transverse divergence, which will be lost in the rest of the ILC positron source beamline. A collimation system is proposed and optimized for the case of a shielded target with quarter-wave transformation collection optics so that the power loss in the magnets and RF structures is effectively controlled within the acceptable level and in the damping ring (DR) within 640 W, assuming 3× 1010 of the captured positrons per bunch in the DR. In this case, the capture efficiency and DR injection efficiency are 13% and 99.8%, respectively. The lower capture efficiency is expected to result in higher injection efficiency and therefore, a lower power loss in the DR. The capture efficiency for the cases of a shielded target with flux concentrator and 5-T immersed target with flux concentrator is 20% and 30%, respectively, with the collimation system.  
 
MOPP050 Electron Cloud Build Up and Instability in the CLIC Damping Rings electron, wiggler, simulation, damping 661
 
  • G. Rumolo, Y. Papaphilippou
    CERN, Geneva
  • W. Bruns
    WBFB, Berlin
  Electron cloud can be formed in the CLIC positron damping ring and cause intolerable tune shift and beam instability. 2D and 3D build up simulations with the Faktor2 code, developed at CERN, have been done to predict the cloud formation in the arcs and wigglers of the damping rings. HEADTAIL simulations have been used to study the effect of this electron cloud on the beam and assess the thresholds above which the electron cloud instability would set in.  
 
MOPP057 ILC DR Vacuum Design and E-cloud electron, vacuum, photon, dipole 673
 
  • O. B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • W. Bruns
    WBFB, Berlin
  An electron cloud parameters and vacuum design are tightly bounded to each other. Input parameters for the e-cloud depend on shape of vacuum chamber and surface property (material, roughthness, coatings, etc.), electron multipacting in the vacuum chamber causes the electron stimulated gas desorption and may require modification of vacuum system to deal with it. This paper describes the e-cloud modelling performed in a way to optimise ILC DR vacuum design in positron ring and to have clear understanding what modification in vacuum chamber are required. Three parameters of e-cloud were varied in turn: photo-electron emission, secondary electron yield and gas pressure. It was found all three parameter should not exceed certain value to keep the e-cloud density to an acceptable level. The energy and intensity of electron bombardment of the vacuum chamber walls and electron stimulated gas desorption were also calculated. It was found that electron stimulated gas desorption is comparable or larger than the photon stimulated desorption and should be considered in vacuum design.  
 
MOPP064 Secondary Electron Yield Measurements and Groove Chambers Update Tests in the PEP-II Beam Line electron, vacuum, simulation, storage-ring 691
 
  • M. T.F. Pivi, F. King, R. E. Kirby, T. W. Markiewicz, T. O. Raubenheimer, J. Seeman, L. Wang
    SLAC, Menlo Park, California
  In the Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in straight sections to test this possible mitigation technique for the electron cloud effect in the positron damping ring (DR) of the future Linear Colliders such as ILC and CLIC. We have also installed chambers to monitor the secondary electron yield (SEY) of TiN, TiZrV (NEG) and technical accelerator materials under the effect of electron and photon conditioning in situ. Furthermore, we have also installed test chambers in a new 4-magnet chicane. We describe the ongoing R&D effort to mitigate the electron cloud effect in the ILC damping ring, the chambers installation in the PEP-II and latest results.  
 
MOPP069 A Prototype Target Wheel for the ILC Positron Source target, photon, undulator, simulation 706
 
  • I. R. Bailey, L. J. Jenner, C. J. Nelson
    Liverpool University, Science Faculty, Liverpool
  • I. R. Bailey
    Cockcroft Institute, Warrington, Cheshire
  • D. G. Clarke, K. P. Davies, A. Gallagher
    STFC/DL, Daresbury, Warrington, Cheshire
  • J. A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. Gronberg, L. B. Hagler, W. T. Piggott
    LLNL, Livermore, California
  In this paper we describe the design, construction and commissioning of a prototype based on the positron production target wheel planned for the ILC positron source. The efficiency of the current baseline positron source design for the ILC can be improved if the conversion target is partially immersed in the magnetic field of the capture optics, thereby increasing the overall capture efficiency for positrons by a factor of two or more. However, immersion of the rotating target wheel generates strong eddy currents leading to additional heating and stresses on the wheel. The primary purpose of our prototype, which had been assembled at Daresbury Laboratory, is to investigate the effects of eddy currents induced in a titanium alloy wheel moving with rim speeds up to 100 metres per second in magnetic fields of the order of 1 Tesla.  
 
MOPP070 Construction of a Full Scale Superconducting Undulator Module for the International Linear Collider Positron Source undulator, vacuum, photon, electron 709
 
  • J. A. Clarke, O. B. Malyshev, D. J. Scott, B. J.A. Shepherd
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • I. R. Bailey, J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva, L. Zang
    Liverpool University, Science Faculty, Liverpool
  • E. Baynham, T. W. Bradshaw, A. J. Brummitt, F. S. Carr, A. J. Lintern, J. Rochford
    STFC/RAL, Chilton, Didcot, Oxon
  • A. Bungau
    UMAN, Manchester
  • N. A. Collomb
    STFC/DL, Daresbury, Warrington, Cheshire
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  • S. Hesselbach, G. A. Moortgat-Pick
    Durham University, Durham
  • Y. Ivanyushenkov
    ANL, Argonne, Illinois
  • N. C. Ryder
    University of Bristol, Bristol
  The positron source for the ILC is dependent upon a >200m long undulator to generate a high flux of multi-MeV photons. The undulator system is broken down into a series of 4m cryomodules, which each contain two superconducting helical undulators. Following a dedicated R&D phase and the construction and measurement of a number of short prototypes a full scale cryomodule has now been completed for the first time. This paper reports on the design, manufacture, and test results of this cryomodule.  
 
MOPP072 A Study of Mechanical and Magnetic Issues for a Prototype Positron Source Target target, simulation, photon, undulator 715
 
  • L. J. Jenner, I. R. Bailey
    Cockcroft Institute, Warrington, Cheshire
  • D. G. Clarke, K. P. Davies, A. Gallagher
    STFC/DL, Daresbury, Warrington, Cheshire
  • J. A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. Gronberg, L. B. Hagler, W. T. Piggott
    LLNL, Livermore, California
  • S. Hesselbach
    Durham University, Durham
  • C. J. Nelson
    STFC/RAL, Chilton, Didcot, Oxon
  • J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  In order to construct a high yield, positron source that can meet the intensity requirements of future facilities, a robust conversion target is needed. One solution is to use a rotating titanium alloy wheel upon which a beam of photons is incident. The efficiency of capturing the resulting positrons can be optimised by immersing this system in a magnetic field. As described elsewhere*, a prototype of such a target has been built at Daresbury Laboratory, to investigate the mechanical challenges associated with its construction and to study the magnetic effects that the wheel will experience. In this paper, calibration of the instrumentation, the data acquisition system and the initial results from operating the wheel in a strong magnetic field are described. Such phenomena as the eddy current heating experienced by the wheel are measured and compared to results from modelling codes. Vibrational issues surrounding the wheel and supporting structure at various speeds are studied.

*ID: 3894 A Prototype Target Wheel for the ILC Positron Source

 
 
MOPP079 Studies on the Role of a Photon Collimator for the ILC Positron Source photon, undulator, radiation, simulation 733
 
  • L. Zang
    Cockcroft Institute, Warrington, Cheshire
  • I. R. Bailey, A. Wolski, L. Zang
    Liverpool University, Science Faculty, Liverpool
  Use of a helical undulator in the ILC positron source provides the possibility of producing a polarised positron beam. The degree of polarisation of the positrons depends upon the polarisation of the photons produced from the undulator, where the polarisation depends on the photon energy and production angle. We calculate these quantities for one design of the helical undulator for the ILC, investigate approximations commonly made in calculating the undulator photon spectrum and explore the role of of a photon collimator in determining the positron polarisation.  
 
TUOBG01 Observations of Beam-beam Tune Spectrum and Measurement of Coherent Tune Shift at KEKB luminosity, electron, emittance, betatron 962
 
  • T. Ieiri, Y. Ohnishi, M. Tobiyama, S. Uehara
    KEK, Ibaraki
  KEKB is a double-ring electron/positron collider with a horizontal crossing angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. Under the new crabbing collision as well as the horizontal crossing collision, tune spectra of a colliding bunch were observed on a spectrum analyzer to study beam-beam effects. The beam-beam spectrum showed strong nonlinear resonant phenomena. Considering the nonlinearity, the coherent beam-beam tune shift was measured as a function of the bunch current. It was confirmed that the vertical beam-beam parameter estimated from the coherent beam-beam tune shift agreed with a value obtained from a bunch-by-bunch luminosity monitor. The estimated vertical beam-beam parameter was saturated on a level of about 0.04, which is called a beam-beam limit. We found that the bunch current corresponding to the beam-beam limit was far below the bunch current used in the usual operation.  
slides icon Slides  
 
TUPC008 Beam Diagnostics with IR Light Emitted by Positron at DAΦNE diagnostics, radiation, synchrotron, synchrotron-radiation 1056
 
  • A. Bocci, A. Clozza, A. Drago, A. G. Grilli, A. Marcelli, A. R. Raco, R. S. Sorchetti
    INFN/LNF, Frascati (Roma)
  • A. De Sio, L. Gambicorti, E. Pace
    Università degli Studi di Firenze, Firenze
  • E. P. Emanuele
    Università degli Studi di Firenze, Firenze
  • M. P. Piccinini
    Università Roma Tre, Roma
  • J. P. Piotrowski
    Vigo System Sa, Warsaw
  Real-time beam diagnostics is mandatory in accelerators and represents one of the most challenging issues of modern storage rings and future FEL's. Recently, compact mid-IR fast uncooled photo-detectors have been used at DAΦNE to monitor single e- bunches using the SINBAD IR beamline installed on the e- ring*. Electron bunches have a FWHM of 150-300 ps and are separated by 2.7 ns**. Detectors performances are then suitable for a compact and low cost bunch-by-bunch longitudinal diagnostic device. To improve the DAΦNE diagnostic a bending magnet SR port on the e+ ring has been set-up with a HV chamber, a gold-coated plane mirror and a ZnSe window. To collect the SR light and focus radiation on IR detectors allowing the diagnostic of e+ a compact optical system has been installed in air after the window. Here we will present the status of the apparatus, the source characteristics, the optical setup and the complete acquisition system. This IR port will allow comparison in the ns time domain between data collected on both rings, and could be also used to improve DAΦNE diagnostics, i.e., identify and characterize bunch instabilities and/or increase the current in the e+ ring.

*M. Cestelli Guidi et al. J. Opt. Soc. Amer. A 22, 2810 (2005).
**A. Bocci et al. NIM-A, 580, 190 (2007).

 
 
TUPC040 Measurements of Beam-beam Kick using a Gated Beam-position Monitor under Crabbing Collision at KEKB electron, betatron, beam-beam-effects, luminosity 1143
 
  • T. Ieiri, H. Fukuma, Y. Funakoshi, M. Masuzawa, K. Ohmi, M. Tobiyama
    KEK, Ibaraki
  KEKB is a double-ring electron/positron collider with a horizontal crossing-angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. A gated beam-position monitor is a tool to measure the beam-beam effects. A beam-beam kick curve was measured by comparing the beam position between colliding and non-colliding bunches, while shifting the beam orbit at the interaction point (IP). An effective horizontal beam size at the IP was obtained from a linear part of the beam-beam kick around the central orbit. The estimated beam size agreed with a calculated value including the dynamic effects. It was confirmed that the effective horizontal beam size was reduced by the crabbing collision, as expected from a calculation with a rigid Gaussian model. When a horizontal orbit offset was larger than a beam size, however, we found that the measured beam-beam kick curve deviated from calculated values using the Gaussian model. The result suggests that the beam profile might enlarge horizontally in the peripheral part.  
 
TUPD010 High-power Switch with SI-thyristor for the Power Supply of Very High Repletion Rate Pulsed Quadrupole Magnet quadrupole, power-supply, induction, kicker 1452
 
  • T. Mimashi, M. Kikuchi
    KEK, Ibaraki
  • A. Tokuchi, K. Tsuchida
    Nichicon (Kusatsu) Corporation, Shiga
  A solid-state switch with SI-thyristors is implemented as the high power switch for the pulsed quadrupole magnet power supply. Its repletion rate is 100 kHz with the half sign 1 microsecond pulse. The switch has been successfully operated.  
 
TUPD011 The Pulsed Quadrupole Magnet for KEKB Low Energy Ring quadrupole, focusing, luminosity, electron 1455
 
  • T. Mimashi, T. Ieiri, M. Kikuchi
    KEK, Ibaraki
  • A. Tokuchi, K. Tsuchida
    Nichicon (Kusatsu) Corporation, Shiga
  In the KEKB low energy ring, because of photoelectron clouds, the betatron tune changes along the position in the train. The produced photoelectron gives focusing force to the beam. It is remarkable especially in the vertical tune. Since we have a 500 nanoseconds beam abort gap, the photoelectron focusing force is weaker at the head of train. It means the vertical tune is lower at the head of the train. In order to cancel this tune shift, the pulsed quadrupole magnet was installed. The pulsed quadrupole magnet system and its performance are described.  
 
TUPD038 Beam Test of a Movable Collimator (Mask) with Low Beam Impedance impedance, vacuum, simulation, collider 1511
 
  • Y. Suetsugu, K. Shibata
    KEK, Ibaraki
  • A. Morishige, Y. Suzuki, M. Tsuchiya
    Kinzoku Giken Co. Ltd., Ebina
  A movable collimator with low beam impedance for future high-intensity machines has been investigated in KEK*. The metal head of the collimator is supported by a dielectric material in order to reduce the interference with beams. The first test model was installed into the KEK B-factory (KEKB) positron ring last year. The head and the support was alumina ceramic, but only the head was coated by copper to realize a conductive layer. The support, however, was finally melted during the beam operation due to the overheating by intense electromagnetic fields induced by bunches. Based on the experience, the design was revised and the second test model was manufactured, where the head and the support were made of graphite and artificial diamond, respectively. Graphite is a conductive material with high thermal strength, and diamond, on the other hand, is a dielectric material with high thermal conductivity as well as the strength. The second test model is installed in the spring of this year, and tested again with beams during the beam operation to prove the principle. The results of the beam tests will be presented here.

* Y. Suetsugu, K. Shibata, A. Morishige, Y. Suzuki, M. Tsuchiya, “Design Study of a Movable Mask with Low Bema Impedance”, PRST-AB, 9, 2006, 103501.

 
 
TUPP031 Electron Cloud Simulations for DAΦNE electron, wiggler, simulation, vacuum 1604
 
  • T. Demma, R. Cimino, S. Guiducci, C. Vaccarezza, M. Zobov
    INFN/LNF, Frascati (Roma)
  After the first experimental observations compatible with the presence of the electron cloud effect in the DAΦNE positron ring, a systematic study has been performed regarding the electron cloud build-up. To assess the effects of the electron cloud, simulations of the cloud build up were carried out using ECLOUD. In particular, we discuss modifications to the secondary emission model, build up for various filling patterns and different wiggler magnetic field models. The obtained numerical results are compared with experimental observations.  
 
TUPP071 Development of TiN Coating System for Beam Ducts of KEK B-factory electron, cathode, controls, luminosity 1700
 
  • K. Shibata, H. Hisamatsu, K.-I. Kanazawa, M. Shirai, Y. Suetsugu
    KEK, Ibaraki
  A titanium nitride (TiN) coating system for the copper beam ducts of KEK B-factory (KEKB) was developed to reduce the secondary electron yield (SEY) from the inner surface, which would mitigate the electron cloud instability. The coating was done by DC magnetron sputtering of titanium in argon and nitrogen atmospheres. The duct was set vertically, and a titanium cathode rod was hung from the top on the center axis of the duct. A magnetic field was supplied by a movable solenoid coil placed outside of the duct. Preliminary experiments using small copper samples showed that a 200-nanometer-thick TiN film coated at 150 degree is the best from the viewpoints of SEY and adhesion strength. The SEY of the coated sample decreased to 60% of that of non-coated copper after an electron dose of 0.01 C/mm2, and the maximum SEY was 0.84. Using this system, five ducts with a length of up to 3.6 m were successfully coated. Some of them were installed into the KEKB positron ring last summer, and no problem was found in the following beam operation with a beam current of up to 1.6 A. One coated duct with an electron monitor was installed this winter, and the effect of the coating will be checked.  
 
TUPP079 Distortion of Crabbed Bunch due to Electron Cloud with Global Crab electron, betatron, luminosity, optics 1715
 
  • L. Wang, Y. Cai, T. O. Raubenheimer
    SLAC, Menlo Park, California
  In order to improve the luminosity, crab cavities have been installed in the KEKB HER and LER. Since there is only one crab cavity in each ring, the crab cavity generates a horizontally titled bunch oscillating around the whole ring. The electron cloud in LER (positron beam) may distort the crabbed bunch and cause the luminosity drop. This paper briefly estimates the distortion of positron bunch due to the electron cloud with global crab.  
 
TUPP098 The 3D Space Charge Field Solver MOEVE and the 2D Bassetti-Erskine Formula in the Context of Beam - E-cloud Interaction Simulations simulation, space-charge, damping, electron 1759
 
  • A. Markovik, G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock
  In this paper the fields computed with our 3D space charge field solver MOEVE are compared to those obtained by means of the Bassetti-Erskine formula, which is a widely used 2D approximation of the electric field of a Gaussian bunch. In particular we are interested in the transversal fields of very flat bunches as the ILC or the KEKB positron bunch. Supposing a longitudinal Gaussian distribution of the bunches, we compare the computed transversal fields for a certain line density of the positron bunch. It turns out that the fields from the 2D and the 3D computation coincide very good.  
 
TUPP151 A High Intensity Positron Source at Saclay: The SOPHI Project target, linac, electron, ion 1863
 
  • O. Delferriere, V. Blideanu, M. Carty, A. Curtoni, L. Liszkay, P. Perez, J. M. Rey, N. Ruiz, Y. Sauce
    CEA, Gif-sur-Yvette
  • F. Forest, J. L. Lancelot, D. Neuveglise
    Sigmaphi, Vannes
  One of the fundamental questions of todays physics concerns the action of gravity upon antimatter. No experimental direct measurement has ever been successfully performed with antimatter particles. An R&D program has been launched at IRFU (CEA/Saclay) to demonstrate the feasibility of the production of antihydrogen (H) with the use of a target of positronium (Ps) atoms. This target, when bombarded with antiprotons, should allow combining its positrons with the incoming antiprotons and create H atoms and H+ ions. This experiment needs a large amount of Ps atoms, thus an intense source of positrons is necessary. We are building the SOPHI experiment in Saclay, based on a small 5 MeV electron linac to produce positrons via pair production on a tungsten target. This device should provide 108 slow e+/s, i.e. a factor 300 greater than the strongest activity Na22 based setups. The SOPHI system has been finalized in 2006 and the main components have been studied and built during 2007. The experiment is currently assembled and first results are expected in June 2008. The Linac, beam production and transport system will be presented, and first positron production rate measurements reported.  
 
WEOBG03 The Design of the Positron Source for the International Linear Collider target, undulator, photon, electron 1915
 
  • J. A. Clarke, O. B. Malyshev, D. J. Scott
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • I. R. Bailey, J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva, L. Zang
    Liverpool University, Science Faculty, Liverpool
  • E. Baynham, T. W. Bradshaw, A. J. Brummitt, F. S. Carr, A. J. Lintern, J. Rochford
    STFC/RAL, Chilton, Didcot, Oxon
  • V. Bharadwaj, J. Sheppard
    SLAC, Menlo Park, California
  • A. Bungau
    UMAN, Manchester
  • N. A. Collomb
    STFC/DL, Daresbury, Warrington, Cheshire
  • R. Dollan
    Humboldt Universität zu Berlin, Berlin
  • W. Gai, Y. Ivanyushenkov, W. Liu
    ANL, Argonne, Illinois
  • J. Gronberg, W. T. Piggott
    LLNL, Livermore, California
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  • S. Hesselbach, G. A. Moortgat-Pick
    Durham University, Durham
  • K. Laihem, S. Riemann, A. Schaelicke, A. Ushakov
    DESY Zeuthen, Zeuthen
  • T. Lohse
    Humboldt University Berlin, Institut für Physik, Berlin
  • A. A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  • N. C. Ryder
    University of Bristol, Bristol
  The high luminosity requirements and the option of a polarized positron beam present a great challenge for the positron source of a future linear collider. This paper provides a comprehensive overview of the latest proposed design for the baseline positron source of the International Linear Collider. We report on recent progress and results concerning the main components of the source: including the undulator, collimators, capture optics, and target.  
slides icon Slides  
 
WEPC026 Laser – Beam Interaction and Calculation of the Sliced Bunch Radiation Spectra for the SLS FEMTO Beam Line electron, laser, wiggler, radiation 2040
 
  • D. K. Kalantaryan, G. A. Amatuni, V. M. Tsakanov
    CANDLE, Yerevan
  • P. Beaud, G. Ingold, A. Streun
    PSI, Villigen
  The FEMTO insertion at the Swiss Light Source (SLS) produces sub-ps X-ray pulses by modulating the electron energy in a slice of the bunch through interaction with a fs-laser. The electron energy modulation by the laser field in the wiggler magnet is studied analytically to calculate the radiation spectra from a sliced bunch. The analytical expressions for energy modulation and its envelope have been derived. The radiation spectra in the first magnet after the FEMTO insertion have been studied. The spectra of the coherent part of the radiation are determined using a Fourier transformation technique. For a Gaussian bunch the obtained results are compared with the tracking simulation study.  
 
WEPD005 Scaling Laws for Magnetic Energy in Superconducting Quadrupoles quadrupole, collider, superconducting-magnet, luminosity 2407
 
  • F. Borgnolutti, E. Todesco
    CERN, Geneva
  • A. Mailfert
    ENSEM, Vandoeuvre lès Nancy
  The stored energy in superconducting magnets is one of the main ingredients needed for the quench calculation and for desingin quench protections. Here we proposed an analytical formula based on the Fourier transformation of the current density flowing within the winding to determine the magnetic energy stored in superconducting quadrupoles made of sector coils. Two corrective coefficients allowing to estimate the energy enhancement produced either by current grading or by the presence of an unsaturated iron yoke are respectively derived from a numerical and an analytical study. This approach is applied to a set of real quadrupoles to test the validity limits of the scaling law, which are shown to be of 5-10%.  
 
WEPP089 Wake-field Suppression in the CLIC Main Linac damping, dipole, coupling, emittance 2725
 
  • V. F. Khan, R. M. Jones
    UMAN, Manchester
  The CLIC linear collider aims at accelerating multiple bunches of electrons and positrons and colliding at a centre of mass energy of 3 TeV. These bunches are accelerated through X-band linacs operating at an accelerating frequency of 12 GHz. Each beam readily excites wake-fields in the accelerating cavities of each linac. The transverse components of the wake-fields, if left unchecked, can dilute the beam emittance. The present CLIC design relies on heavy damping of these wake-fields in order to ameliorate the effects of the wake-field on the beam emittance. Here we present initial results on a modified design which combines both damping and detuning of the cell frequencies of each cavity structure in order to enhance the overall decay of the wake-field. Interleaving of cell frequencies is explored as a means to improve the damping.  
 
WEPP124 The Status of Turkish Accelerator Complex Project factory, linac, electron, synchrotron 2788
 
  • A. Aksoy, Ö. Karsli, B. Ketenoglu, O. Yavas
    Ankara University, Faculty of Engineering, Tandogan, Ankara
  • A. K. Ciftci
    Ankara University, Faculty of Sciences, Tandogan/Ankara
  • S. Sultansoy
    TOBB ETU, Ankara
  The Turkish Accelerator Complex (TAC) is proposed as a regional facility for accelerator based fundamental and applied research in 1997 with support of Turkish State Planning Organization (DPT). The feasibility and conceptual design phases of TAC proposal were completed in 2001 and 2005, respectively. Again with support of DPT, the technical design phase of TAC was started at the beginning of 2006. The complex will include 1 GeV electron linac and 3.56 GeV positron ring for linac on ring type electron-positron collider as a charm factory and a few GeV proton linac. Besides the particle factory, it is also planned to produce SASE FEL from electron linac and synchrotron radiation from positron ring. It is planed that the TDR of TAC Project will be completed in 2011 and the construction will be performed during following ten years .  
 
WEPP157 Lithium Lens for Positron Production System target, optics, focusing, undulator 2856
 
  • A. A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  We represent optimized parameters for undulator-based positron production scheme for ILC-type machine. In particular we describe details of Lithium lens design suggested for usage in collection optics.  
 
WEPP164 Beam Collimation Studies for the ILC Positron Source collimation, emittance, damping, target 2871
 
  • A. I. Drozhdin
    Fermilab, Batavia, Illinois
  • Y. Nosochkov, F. Zhou
    SLAC, Menlo Park, California
  The results of collimation studies for the ILC positron source beam line are presented. The calculations of primary positron beam loss are done using the ELEGANT code. The secondary positron and electron beam loss, synchrotron radiation along the beam line and bremsstrahlung radiation in the collimators are simulated using the STRUCT code. The first part of the system, located right after the positron source target at 0.125 GeV, is used for protection of super-conducting RF Linac from heating and radiation. The second part of the system is used for final collimation of the beam before injection to the Damping Ring at 5 GeV. The calculated power loss in the collimation region is about 100 W/m, with loss in the collimators of 0.2-5 kW. The beam transfer efficiency from target to the Damping Ring is 13.5%.  
 
THXM02 Development of the KEK-B Superconducting Crab Cavity electron, superconductivity, cryogenics, acceleration 2927
 
  • K. Hosoyama, K. Akai, K. Ebihara, T. Furuya, K. Hara, T. Honma, A. Kabe, Y. Kojima, S. Mitsunobu, Y. Morita, H. Nakai, K. Nakanishi, M. Ono, Y. Yamamoto
    KEK, Ibaraki
  • H. Hara, K. Okubo, K. Sennyu, T. Yanagisawa
    MHI, Kobe
  The development of the KEK-B superconducting crab cavity, including the design, production, tests and latest parameter performances should be described in this talk.  
slides icon Slides  
 
THPC018 Beam Dynamics Issues in the CLIC Long Transfer Line ion, electron, injection, emittance 3017
 
  • J. B. Jeanneret, E. Adli, A. Latina, G. Rumolo, D. Schulte, R. Tomas
    CERN, Geneva
  Both the main beam and the drive beam of the CLIC project must be transported from the central production site to the head of the main linacs over more than twenty kilometres. Over such distances chromatic aberrations are substantial. With long distances and large beam currents, detuning and instabilities associated to ion production and multi-bunch resistive wall effects must also be considered. These effects are quantified and simulated. Based on these results, we propose a baseline design for these two lines.  
 
THPC143 A Wide Range Electrons, Photons, Neutrons Beam Facility electron, linac, photon, diagnostics 3321
 
  • B. Buonomo, G. Mazzitelli, F. Murtas, L. Quintieri
    INFN/LNF, Frascati (Roma)
  • P. Valente
    INFN-Roma, Roma
  The DAΦNE Beam Test Facility is in operation since the 2003 and has been continuously improved and upgraded in order to take into account the many different requests coming from the high energy and accelerator community. The facility was initially optimized to produce single electron and positron in the 25-750 MeV energy rage, manly for high energy detector calibration and testing; it can now provide beam in a wider range of intensity, up to 1010 electrons/pulse, typically needed for accelerator diagnostic tests. In the last two years the facility has also been modified in order to produce tagged photons, and the possibility to deliver tagged neutrons in the MeV energy range is under study. The main results obtained, the performance and the most significant characteristics of the facility diagnostics and operation are presented, as well as the users experience collected during these years of operation.  
 
THPP151 Feasibility Study for High Performance Vacuum Chamber photon, vacuum, electron, storage-ring 3720
 
  • Y. Tanimoto
    KEK, Ibaraki
  For longer beam lifetime, many synchrotron light sources employ ante-chamber type of beam ducts to reduce photon- and electron-stimulated desorption gases around stored beams. Still more reduction, however, can be expected if an X-ray transparent membrane, such as Beryllium thin film, is installed between the beam chamber and the ante-chamber because X-rays from stored beams pass through the membrane while gas molecules desorbed in the ante-chamber are shut out by the membrane. Similarly, photoelectrons and secondary electrons traveling from the ante-chamber to the beam chamber are also shut out by the membrane; this function is expected to mitigate beam-photoelectron instability in positron storage rings. Feasibility study for this type of vacuum chamber has been started at PF, and the result of the first-stage experiment will be presented.