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MOXPA02 SCRF Test Facilities toward the ILC TTF, DESY, XFEL, linac 5
 
  • K. Saito
    KEK, Ibaraki
  After the ICFA selection of the superconducting linear collider technology in August 2004, many intensive R&D programs are in the planning stage or already underway. Work is proceeding in the three major geographical regions involved in the ILC: Europe(TTF), North America (SMTF) and Asia (STF). In this paper, the global activity represented by these superconducting RF test facilities will be reviewed. Their goals, plans, schedules and possible complementarities will be presented. The performance expected from the different R&D efforts by 2008, and the corresponding contribution to the ILC Technical Design Report, will be especially emphasized.  
slides icon Transparencies
 
MOPCH119 Present Status of the Induction Synchrotron Experiment in the KEK PS induction, acceleration, synchrotron, proton 324
 
  • K. Takayama, Y. Arakida, T. Iwashita, T. Kono, E. Nakamura, Y. Shimosaki, M.J. Shirakata, T. Sueno, K. Torikai
    KEK, Ibaraki
  • K. Otsuka
    Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture
  A concept of the induction synchrotron, which was proposed by Takayama and Kishiro in 2000, has been demonstrated by using the KEK PS since 2004. A proton bunch trapped in the RF bucket was accelerated with the induction acceleration devices from 500 MeV to 8 GeV*, which was energized with the newly developed switching power supply. This form of the KEK PS is something like a hybrid synchrotron. In addition, the injected proton bunch was confined by the step barrier-voltages at the injection energy of 500MeV**, which were generated with the same induction acceleration device. Then a concept of the induction synchrotron that a proton bunch was captured by the barrier bucket and accelerated with the induction voltage is to be fully demonstrated.

*K. Takayama et al. "Observation of the Acceleration of a Single Bunch by Using the Induction Device in the KEK Proton Synchrotron", Phys. Rev. Lett., 94, 144801 (2005).**K. Torikai et al. "Acceleration and Confinement of a Proton Bunch with the Induction Acceleration System in the KEK Proton Synchrotron", submitted to Phys. Rev. ST-AB (2005), KEK-Preprint 2005-80 A, December 2005.

 
 
MOPCH120 Ground Motion Study and the Related Effects on the J-PARC ground-motion, site, simulation, beam-losses 327
 
  • S. Takeda, N. Yamamoto, M. Yoshioka
    KEK, Ibaraki
  • Y. Nakayama
    JPOWER, Kanagawa-ken
  The power spectrum density, coherence and cross-spectrum density of the ground motion in the J-PARC site are studied to get the guideline of the beam control systems. J-PARC consists of a 600 MeV linac, a 3 GeV Rapid-cycling synchrotron (RCS) and a 50 GeV synchrotron (MR). MR provides a beam current of 15 micro-A with a period of 3 sec to either the nuclear physics experimental area or the neutrino production target. MR is a very high beam power machine, so its optimum beam loss must be kept fewer than 0.01% of an accelerated beam in order to decrease the radiation damage of accelerator components and to get easy accessibilty to them. From the point of view of beam loss, we give some detailed discussion about the relation between the MR operation and the ground motion using the observed data.  
 
MOPCH121 Ground Motion Measurement at J-PARC ground-motion, site, KEKB, SLAC 330
 
  • Y. Nakayama, K. Tada
    JPOWER, Kanagawa-ken
  • S. Takeda, M. Yoshioka
    KEK, Ibaraki
  In the next generation accelerator, construction of the machine on the stable ground is preferable for accelerator beam operation. We have measured ground motion at the J-PARC site under construction, where the ground is very close to the Pacific Ocean. In this paper, some of the observed results are shown, comparing the results of the previous observation at some accelerator facilities and next generation accelerator candidate sites in Japan.  
 
MOPCH179 Design of a New Electropolishing System for SRF Cavities DESY, TESLA, controls, LANL 484
 
  • T. Tajima
    LANL, Los Alamos, New Mexico
  • C. Boffo
    Fermilab, Batavia, Illinois
  • M.P. Kelly
    ANL, Argonne, Illinois
  • J. Mammosser
    Jefferson Lab, Newport News, Virginia
  Electropolishing (EP) is considered the baseline surface treatment for Superconducting RF (SRF) cavities to achieve >35 MV/m accelerating gradient for the International Linear Collider (ILC). Based on the lessons learned at the forerunners such as KEK/Nomura, DESY and JLAB and on the recent studies, we have started a new design of the next EP system that will be installed in the US. This paper presents requirements, specifications, and the detail of the system design as well as the path forward towards the future industrialization.  
 
MOPCH190 Cryomodule Development for Superconducting RF Test Facility (STF) at KEK TESLA, vacuum, superconducting-RF, alignment 505
 
  • K. Tsuchiya, H. Hayano, Y. Higashi, H. Hisamatsu, M. Masuzawa, H. Matsumoto, C. Mitsuda, S. Noguchi, N. Ohuchi, T. Okamura, K. Saito, A. Terashima, N. Toge
    KEK, Ibaraki
  Current status of the cryomodule development for superconducting RF test facility, STF, at KEK is presented. The objective of the STF construction is to have an experience of 5-m long cryomodule fabrications and to learn an operational method of superconducting RF cavities. The STF consists of two 5-m long cryomodules, each housing four 9-cell cavities (one for 35 MV/m and the other for 45 MV/m). In addition to the cavity type, each cavity has variations in its appendices. Thus, two cryomodules must have different structures for the cavity support and for the port of the RF input coupler. This paper describes the details of the cryomodule design, the development of the bimetallic joint for connecting the titanium helium vessel to the stainless steel cooling pipe, and the studies of the magnetic shielding for high quality cavities.  
 
MOPLS083 Higher Order Mode Study of Superconducting Cavity for ILC Baseline polarization, pick-up, coupling, dipole 747
 
  • K. Watanabe
    GUAS/AS, Ibaraki
  • H. Hayano, E. Kako, S. Noguchi, T. Shishido
    KEK, Ibaraki
  The superconducting cavity of ILC baseline shape is being developed at KEK-STF (Superconducting RF Test Facility). The Higher Order Mode (HOM) of the cavity is one study item for the development. The purpose of the HOM study is further optimization of TTF HOM coupler and measurement of the HOM field distribution and the polarization of the main dipole modes. The result will be applied to HOM readings of beam induced signal for the purpose of cavity offset position and angle of axis measurement relative to the beam. We tried to improve of TESLA-type HOM coupler for more small size and relaxation of second stop-band. The cold-model coupler was made, and the RF characteristic was measured. After HOM couplers welded to the KEK Baseline nine-cell SC cavity, Qext of fundamental mode and each HOM, field pattern of each HOM and polarization of dipole modes were measured by the network analyzer. The results of the improved HOM coupler are presented.  
 
MOPLS084 Experimental Comparison at KEK of High Gradient Performance of Different Single Cell Superconducting Cavity Designs DESY, TESLA, controls, superconductivity 750
 
  • F. Furuta, Y. Higashi, T. Higo, I.H. Inoue, S. Kazakov, Y. Kobayashi, H. Matsumoto, Y. Morozumi, R.S. Orr, T. Saeki, K. Saito, K. Ueno, H. Yamaoka
    KEK, Ibaraki
  • J.S. Sekutowicz
    DESY, Hamburg
  We have performed a series of vertical tests of three different designs of single cell Niobium superconducting cavities at 2 degrees Kelvin. These tests aimed at establishing that an accelerating gradient of 45 MV/m could be reached in any of the designs, while using the standard KEK surface preparation. The designs tested were the Cornell re-entrant shape (RE), the DESY/KEK low loss shape (LL), and the KEK ICHIRO series. The cavities underwent surface preparation consisting of centrifugal barrel polishing, light chemical polishing, electropolishing, and finally a high pressure water rinse. All three kinds of cavities were used in a series of vertical tests to investigate details of the surface treatment. When using ultra-pure water for the high pressure rinse, the LL cavity reproducibly exceeded a gradient of 45 MV/m, the RE design reproducibly reached a gradient of between 50 MV/m and 52 MV/m, and three of the six ICHIRO cavities reached a gradient of between 45 MV/m and 49 MV/m.  
 
MOPLS085 Experience with a Zero Impedance Vacuum Flange at He Super-Leak Temperature for the ILC vacuum, impedance, ion, target 753
 
  • H. Matsumoto, F. Furuta, I.H. Inoue, K. Saito, S.N. Sakamoto, K. Ueno
    KEK, Ibaraki
  Several tens of thousands of vacuum flanges will be used in the construction of the ILC. So the reliability and large scale reproducibility of these elements are important issue. To arrive at a standardized vacuum flange, a new design of a unisex flange has been developed. This important component has to serve in two roles at He-super-leak temperature; both as an rf seal and as a vacuum seal. We chose the unisex type with a 90-degree sharp edge forming the seal. The design is a modification of the DESY S-band rectangular waveguide flange. The variation in flatness between the flange and gasket along the inside wall is within 50 micrometer. This should present zero impedance for a bunched beam and for rf power. The He-super-leak performance was measured using the "build up method", i.e.the test was carried out for three hours at 2 degrees Kelvin. The measured He leak rate was below 1·10-13 Atm*cc/sec for a test flange after three successive tests. We describe the design concept and the operational experience at various rf frequencies. These span the frequency range corresponding to warm and cold accelerators.  
 
MOPLS087 Series Test of High-gradient Single-cell Superconducting Cavity for the Establishment of KEK Recipe vacuum, electron, pick-up, superconductivity 756
 
  • T. Saeki, F. Furuta, Y. Higashi, T. Higo, S. Kazakov, H. Matsumoto, Y. Morozumi, K. Saito, N. Toge, K. Ueno, H. Yamaoka
    KEK, Ibaraki
  • M.Q. Ge
    IHEP Beijing, Beijing
  • K. Kim
    Kyungpook National University, Daegu
  • R.S. Orr
    University of Toronto, Toronto, Ontario
  We have performed a series of vertical tests of single cell Niobium superconducting cavities at 2 degrees Kelvin. These tests aimed at establishing the feasibility of reaching an accelerating gradient of 45 MV/m on a routine basis. The cavity profiles were all of the KEK low loss design and were fabricated from deep drawn Niobium half shells using electron beam welding. The cavity surface preparation followed an established KEK procedure of centrifugal barrel polishing, light chemical polishing, high temperature annealing, electropolishing, and finally a high pressure water rinse. Of the six cavities tested, three exceeded 45 MV/m on the first test. This clearly establishes the feasibility of this gradient. In this paper we describe these tests and our future program for optimising the surface preparation.  
 
MOPLS122 Design of the ILC Prototype FONT4 Digital Intra-train Beam-based Feedback System feedback, kicker, extraction, linear-collider 849
 
  • P. Burrows
    Queen Mary University of London, London
  • G.B. Christian, H. Dabiri Khah, A.F. Hartin, G.R. White
    JAI, Oxford
  • C.C. Clarke, C. Perry
    OXFORDphysics, Oxford, Oxon
  • A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • D.J. McCormick, S. Molloy, M.C. Ross
    SLAC, Menlo Park, California
  We report on the design and initial testing of the 4th generation Feedback on Nanosecond Timescales (FONT) prototype intra-train beam-based feedback system for beam control and luminosity optimisation at the International Linear Collider (ILC). FONT4 comprises a fast-analogue front-end BPM signal processor, with an FPGA-based digital feedback processor and a fast-risetime kicker-driver amplifier. The system is being designed with a total latency budget (including signal propagation delays) of about 140ns. FONT4 will be deployed at the Accelerator Test Facility (ATF) at KEK, where it will be tested with the electron bunchtrain extracted from the ATF damping ring. The bunches will have a spacing of c. 150ns, chosen to match the ILC design. We report the results of initial beam tests of the system components. We aim to demonstrate feedback, with delay-loop operation, on this ILC-like bunchtrain.  
 
TUYPA03 Developments in Beam Instrumentation and New Feedback Systems for the ILC feedback, laser, damping, controls 925
 
  • H. Hayano
    KEK, Ibaraki
  This presentation will review the challenging beam properties that need to be measured and controlled and new diagnostic developments that address these challenges for ILC beam instrumentation.  
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TUPCH057 A Diagnostic System for Beam Abort at KEKB beam-losses, KEKB, vacuum, controls 1139
 
  • H. Ikeda, K. Akai, J.W. Flanagan, T. Furuya, S. Hiramatsu, M. Suetake, Y. Suetsugu, M. Tobiyama, T. Tsuboyama
    KEK, Ibaraki
  • S. Stanic
    Tsukuba University, Ibaraki
  A controlled beam abort system has been installed at KEKB for the protection of the hardware components of the accelerator and detector from damage by ampere-class beam currents. In order to identify the reason for each abort and optimize the abort system to handle each type of problem as well as improve machine operation, a diagnostic system has been developed. Fast signals, such as beam currents, accelerating voltages of the RF cavities and beam loss monitor signals from PIN photo-diodes are recorded and analyzed by a data logger system with a high sampling rate at the moment of each abort. Beam oscillations, radiation dose at the detector and vacuum pressure are also examined to classify the reasons for beam loss and aborts. Statistics and typical examples of these aborts will be discussed.  
 
TUPCH058 Very Small Beam Size Measurement by Reflective SR Interferometer at KEK-ATF emittance, optics, coupling, damping 1142
 
  • T. Naito, T. Mitsuhashi
    KEK, Ibaraki
  An SR interferometer with the Herschelian reflective optics has been developed for the measurement of several um beam size. The chromatic aberration of the optical system applied in the SR interferometer limits the resolution of SR interferometer. We used objective lens of the SR interferometer by a focusing mirror. For the convenience of observation of the interferogram, we applied Herschelian arrangement of the optics. The measured vertical beam size was less than 5um and the estimated vertical emittance was 1x10-11m at the KEK-ATF damping ring.  
 
TUPCH061 Installation of Beam Monitor Sensors in the LINAC Section of J-PARC linac, quadrupole, vacuum, pick-up 1151
 
  • S. Sato, H. Ao, T. Tomisawa, A. Ueno
    JAEA/LINAC, Ibaraki-ken
  • H. Akikawa
    JAEA, Ibaraki-ken
  • Z. Igarashi, S. Lee
    KEK, Ibaraki
  In the LINAC section of J-PARC, we have several type of sensors of monitor, i.e, Beam Position Monitor, Beam Profile Monitor, Beam Size Monitor, Current Monitor, Beam Phase Monitor, Beam Loss Monitor. Those sensors are being installed currently. The procedures, remarks during the installation, status are described in this paper. As an examle, the beam postion monitors are one of sensors which are taken cared intensively for their positioning on their housing quadrupole magnet, then our cares during their installation are described .  
 
TUPCH126 Outgassing Rate of Highly Pure Copper Electroplating Applied to RF Cavities vacuum, linac, LEFT, simulation 1307
 
  • T. Abe, T. Kageyama, Y. Saito, H. Sakai, Y. Sato, Y. Takeuchi
    KEK, Ibaraki
  • Z. Kabeya, T. Kawasumi
    MHI, Nagoya
  • T. Nakamura, S. Nishihashi, K. Tsujimoto
    Asahi Kinzoku Co., Ltd., Gifu
  • K. Tajiri
    Churyo Engineering Co., Ltd., Nagoya
  We plan to apply a new copper electroplating with a high purity and a high electric conductivity to normal-conducting RF cavities for electron or positron storage rings with a high current beam. As reported in 2005 Particle Accelerator Conference, our first test cavity, made of iron, with the electroplated copper surface finished up by electropolishing showed an excellent electric performance compared with the case of cavities made of oxygen free copper. Our next step is to examine the vacuum performance. This paper reports results of the outgassing-rate measurements on our second test cavity together with its fabrication process.  
 
TUPCH127 Fine Grooving of Conductor Surfaces of RF Input Coupler to Suppress Multipactoring electromagnetic-fields, simulation, KEKB, coupling 1310
 
  • T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi
    KEK, Ibaraki
  An RF input coupler to feed high power into an accelerating cavity with heavy beam loading undergoes many multipactoring zones due to the wide range of the input RF power. Furthermore, a regular coaxial line is more subject to multipactoring than a rectangular waveguide because of the uniformity of the electromagnetic field. Grooving the conductor surfaces of the coaxial line is a promising method to suppress multipactoring under any conditions expected in the above cases. This paper reports results of our multipactoring simulation study and the high power test of the input coupler with a grooved coaxial line.  
 
TUPCH128 New Cutting Scheme of Magnetic Alloy Cores for J-PARC Synchrotrons DIAMOND, synchrotron, acceleration, beam-loading 1313
 
  • C. Ohmori, S. Anami, E. Ezura, Y. Funahashi, K. Hara, K. Hasegawa, A. Takagi, M. Toda, K. Ueno, M. Yoshii
    KEK, Ibaraki
  • Y. Morita, T. Yoshioka
    ICEPP, Tokyo
  • M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  A new cutting method using a grindstone was developed to manufacture the magnetic alloy cores. The problem of local temperature rise around the cut surfaces was solved. Long-term high-power tests have been performed for both J-PARC RCS and MR RF systems. Mechanism of local heating, new cutting scheme, and manufacturing method are presented.  
 
TUPLS004 How Einsteinian Tide Force Affects Beam in a Storage Ring storage-ring 1492
 
  • D. Dong
    IHEP Beijing, Beijing
  In this paper, we will introduce Einsteinian tide force into a storage ring, and discuss the beam characteristic in a storage ring, we can see that it is quite different from Newtonian tide force act on beam in a storage ring which we know very well. We also discuss the method to measure the beam instability in storage ring caused by these two different tide forces.  
 
TUPLS028 An Irradiation System for Carbon Stripper Foils with 750 keV H- Beams target, ion, ion-source, linac 1550
 
  • A. Takagi, Y. Arakida, Z. Igarashi, K.I. Ikegami, C. Kubota, I. Sugai, Y. Takeda
    KEK, Ibaraki
  • S. Dairaku, N. Saito, A. Sato, K. Senzaki
    Kyoto University, Kyoto
  • Y. Irie
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  Carbon stripper foils of around 300 ug/cm2 will be used as a stripping of H-ion beam of the 3 GeV Rapid Cycling Synchrotron in the J-PARC. The foil should have a long lifetime with mechanically strong against high temperature of 1800K due to high-energy deposition by high intensity H-ion and circulating bunched proton beam irradiations. For this purpose, we have installed a new irradiation system using high intensity pulsed and dc H-beams of the KEK 750keV Cocksfoot-Walton accelerator. By adjusting the peak intensity and the pulse length of the hydrogen beams appropriately, the energy deposition becomes equivalent to that exerted by the incoming H- and the circulating beams at the injection process of the RCS. The new irradiation system and some preliminary results of the carbon stripper foil will be reported.  
 
TUPLS066 Peculiarities of Electron Cooler Operation and Construction at Ultra Low Energy in an Electrostatic Ring electron, cathode, target, ion 1645
 
  • E. Syresin
    JINR, Dubna, Moscow Region
  Few projects of electrostatic rings with electron cooler are discussed now. Electron cooling at low electron energy of 10 eV was realized at the KEK electrostatic ring. The electron cooling permits to suppress the ion multi scattering on residual gas atoms and allows increasing the ion lifetime. Peculiarities of an electron cooler operation and construction at ultra low energy in an electrostatic ring are considered. The cooler gun operation regime is cardinally changed at a reduction of the electron energy to a value comparable with a cathode work function. A virtual cathode and ohmic resistance of cathode emitter give an input in beam formation at ultra low energy. Effective electron cooling of heavy atomic and bimolecular ions at mass of 100-1000 is reached at a small photocathode diameter of 1 mm and a high magnetic expansion factor of 10-1000. The electron cooler construction has traditional design in KEK electrostatic ring. The cooler construction can be simplified at a small circumference of electrostatic ring. Straight cooler schemes without toroidal magnets permit to reduce ring space required for electron cooler.  
 
TUPLS076 Beam Extraction of 150 MeV FFAG extraction, septum, kicker, power-supply 1672
 
  • M. Aiba, Y. Mori, H. Nakayama, K. Okabe, Y. Sakamoto, A. Takagi
    KEK, Ibaraki
  • R. Taki
    GUAS/AS, Ibaraki
  • Y. Yonemura
    Kyushu University, Fukuoka
  A beam extraction from FFAG accelerator was performed for the first time at KEK 150MeV proton FFAG synchrotron. The purpose of 150MeV FFAG project is to establish a working prototype for various applications. The beam extraction is thus one of important goals. The extraction is based on fast extraction methode using kicker and pulse septum working at 100Hz. A rapid cycling is also our focus to take advantages of FFAG accelerator. Beam extraction experiment was successful under 100Hz operating. The details of experiment will be presented in this paper.  
 
TUPLS106 Pulsed Bending Magnet of the J-PARC MR power-supply, TESLA, synchrotron, simulation 1747
 
  • K. Koseki, H. Kobayashi, H. Nakayama, K.O. Okamura, M.J. Shirakata, M. Tawada
    KEK, Ibaraki
  Japan Proton Accelerator Research Complex (J-PARC) is under construction with a collaboration between Japan Atomic Energy Agency (JAEA) and High Energy Accelerator Research Organization (KEK). The J-PARC consists of a 180 MeV linac, a 3 GeV rapid-cycle synchrotron (RCS) and a 50 GeV synchrotron (MR). The bunch trains, which extracted from the RCS, is delivered both to the “Materials and Life Science Facility” and to the MR, two beam transport lines, 3-NBT and 3-50BT, are constructed. The switching of bunch trains is performed by a pulsed bending magnet. The field strength of 1.21 Tesla with rise and fall time of less than 40 msec is required. It was found that an effect induced by eddy current, which flows at thick end-plates, disturbs the flatness of the magnetic field. A simple compensation circuit has been adopted for a cure. A result from a field measurement, which shows a sufficient flatness, is presented.  
 
WEXPA01 Latest Developments in Superconducting RF Structures for Beta=1 Particle Acceleration TESLA, XFEL, damping, higher-order-mode 1837
 
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  Superconducting RF technology is since nearly a decade routinely applied to different kinds of accelerating devices: linear accelerators, storage rings, synchrotron light sources and FEL's. With the technology recommendation for the International Linear Collider (ILC) a year ago, new emphasis has been placed on improving the performance of accelerating cavities both in Q-value and in accelerating gradients with the goal to achieve performance levels close to the fundamental limits given by the material parameters of the choice material, niobium. This paper will summarize the challenges to SRF technology and will review the latest developments in superconducting structure design. Additionally, it will give an overview of the newest results and will report on the developments in alternative materials and technologies.  
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WEXFI02 Observation and Modeling of Electron Cloud Instability electron, RHIC, LHC, proton 1887
 
  • K.C. Harkay
    ANL, Argonne, Illinois
  This presentation will review experimental results and the state of the art in the analysis and simulation of the electron cloud instability in hadron and positron storage rings.  
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WEPCH130 Analysis of Symmetry in Accelerating Structures with Group Theory RF-structure, polarization, lattice 2227
 
  • S. Sakanaka
    KEK, Ibaraki
  Many rf cavities for modern accelerators have a variety of symmetry. There is a question as to what is the connection between the symmetry of a cavity and of its eigenmodes. This can be clarified* using the representation theory of groups. The geometric symmetry of a cavity can be expressed by a group of symmetry operations. The structure of this group can be represented by a set of matrices called representation. The group is associated with several irreducible representations which can express possible patterns of transformations under the symmetry operations. The irreducible representations are very suitable to express the symmetry of each eigenmode. This method can be used to improve the understanding of non-axially symmetric structures. In this paper, this method is first explained, and then, it is extended to the application of symmetric periodic structures.

*S. Sakanaka, Phys. Rev. ST Accel. Beams 8, 072002 (2005).

 
 
WEPCH145 Particle Tracking and Simulation on the .NET Framework simulation, lattice, controls, closed-orbit 2263
 
  • H. Nishimura, T. Scarvie
    LBNL, Berkeley, California
  Particle tracking and simulation studies are becoming complex. In addition to the sophisticated graphics, interactive scripting is becoming popular. A compatibility with the control system requires network and database capabilities. It is not a trivial task to fulfill various requirements without sacrificing the runtime performance. We evaluate the use of .NET to solve this issue by converting a C++ code Goemon* that is an object-oriented version of Tracy developed at ALS. The portability to other platforms will be mentioned in terms of Mono.

*H. Nishimura, PAC'01, Chicago, July 2001, p.3066.

 
 
WEPCH182 Design of 9.4 GHz 950 keV X-band Linac for Nondestructive Testing electron, linac, gun, target 2358
 
  • T. Yamamoto, T. Natsui, M. Uesaka
    UTNL, Ibaraki
  • M. Akemoto, S. Fukuda, T. Higo, M. Yoshida
    KEK, Ibaraki
  • K. Dobashi
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken
  • E. Tanabe
    AET Japan, Inc., Kawasaki-City
  Mobile "suit-case-sized" x-band (9.4GHz) 950 keV linac is designed for applications of nondestructive testing (NDT). Conventional device for the purpose is the S-band linac, but its drawback is a rather large device-size, large electron beam spot size of about 3 mm and lack of spatial resolution. We aim to realize the smaller spot size about 500 micro-m by a low emittance beam. The proposed system consists of the 9.4 GHz magnetron, modulator, thermionic RF electron gun and 9.4 GHz x-band linac and metal target for x-ray generation. The energy at the gun is 20 keV, and the final energy becomes 950 keV. Now, we are designing the linac structure of the pai/2 mode and analyzing the electromagnetic field (EMF) by SUPERFISH. At this time, we finish analyzing EMF of regular cavity cells and we are analyzing EMF of total accelerating tube. We have finished the detailed RF design. Further, we are also performing the design of the pai mode and going to discuss the advantages and drawbacks between them. Construction of the RF supplying system is underway. The detailed design parameters and updated status of the construction are presented at the spot.  
 
WEPLS129 Upgrade Scheme for the J-PARC Main Ring Magnet Power Supply power-supply, linac, synchrotron, extraction 2679
 
  • H. Sato, K. Koseki, K.O. Okamura, t.s. Shintomi
    KEK, Ibaraki
  Japan Proton Accelerator Research Complex (J-PARC) is under construction at the Tokai campus of Japan Atomic Energy Agency (JAEA) as a joint project between KEK and JAEA. The accelerator complex, which is constructed as a 200 MeV linac, a 3 GeV RCS synchrotron, and a main ring in phase I. The main ring magnet power supply is constructing as the energy of 40 GeV in phase I and will upgrade up to 50 GeV in phase II. A large amount of pulse electric power, which is + 115 MW and -55 MW peak-to-peak, is required for 50 GeV operation and this large pulse power will give unallowable disturbances to a power network. In order to compensate the disturbances to allowable level, we need some energy storage system. A SMES system will be one of the promising means for the purposes as well as the fly-wheel system. We will describe some energy storage system and also the increasing of repetition rate without energy storage system.  
 
THPCH088 A Possibility of Constant Energy Extraction at the KEK ATF2 extraction, synchrotron, feedback, kicker 2994
 
  • A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Beam energy oscillations of the order of 0.02% take place at the KEK ATF. With extractions, the synchrotron oscillation amplitude and phase at the extraction turn randomly fluctuates. The energy jitter causes a position/angle jitter in the Diagnostic section of the Extraction Line. To reduce it, a feed forward energy stabilisation can be used done by extraction of the beam at the turn next to that turn at which the energy passes the equilibrium value. For this, the synchrotron oscillation is measured by a turn-by-turn BPM as a horizontal position oscillation. A fast turn-by-turn processor detects the turn where the oscillation passes zero, and generates an extraction permission signal that triggers the existing ATF Extraction system. Stability improvement by factor of 10 can be obtained even when the extraction is done with uncertainty up to three turns after the trigger.  
 
THPCH094 Fully Digitized Synchronizing and Orbit Feed-back Control System in the KEK Induction Synchrotron induction, controls, synchrotron, acceleration 3012
 
  • K. Torikai, Y. Arakida, Y. Shimosaki, K. Takayama
    KEK, Ibaraki
  A concept of "Induction Synchrotron", where an extremely long bunch captured by the step barrier-voltages is accelerated with the induction accelerating voltage, is being to be fully demonstrated in the KEK 12GeV-PS for the first time*. Attractive applications of the induction synchrotron are such as higher intensity proton drivers, future high luminosity hadron colliders with superbunch, and arbitral-ion accelerators. Synchronization between the voltage-pulse generation and the beam circulation, accelerating voltage control, and beam-orbit control without beam-rf phase, which is analogous to Delta-R feedback in an RF synchrotron, are indispensable in the induction synchrotron. A fully digitized real-time pulse density and discrete timing control system with 1GHz DSPs has been newly developed. Notable characteristics of the control system, some of which are synchronization at 1MHz revolution frequency with 8ns timing accuracy, are explained in detail. Experimental results of the induction acceleration with the digital orbit controller are also presented in this paper.

*K. Torikai et al. "Acceleration and Confinement of a Proton Bunch with the Induction Acceleration System in the KEK Proton Synchrotron", submitted to Phys.Rev.ST-AB(2005), KEK-Preprint 2005-80.

 
 
THPCH115 Timing System Upgrade for Top-up Injection at KEK Linac injection, linac, KEKB, controls 3071
 
  • K. Furukawa, E. Kadokura, A. Kazakov, M. Satoh, T. Suwada
    KEK, Ibaraki
  KEK Linac provides electrons and positrons to Photon Factory (PF) and B-Factory (KEKB). Because of the nature of those factory machines both quantity and quality of the beams are required. In order to improve the injections, quasi top-up injections of electrons to PF and KEKB rings have been planned and a new beam transport line was built. Fast beam switching mechanisms are being developed and installed. The timing and control system is also reinforced to realize fast (50Hz) switching of rf timing pulses, low-level rf, beam instrumentation parameters, and beam feedback parameters. The present timing system provides precise (jitters down to 5ps) timing pulses to 150 devices. Many of the signals will be upgraded to enable the fast switching scheme with an event system. At the same time a double-fold synchronization between asynchronous Linac and PF rf signals was developed to achieve precise injection timing mainly because both rings have independent circumference correction systems.  
 
THPLS076 Status of RF Deflecting Cavity Design for the Generation of Short X-Ray Pulses in the Advanced Photon Source Storage Ring damping, radiation, storage-ring, impedance 3460
 
  • G.J. Waldschmidt, M. Borland, Y.-C. Chae, K.C. Harkay, D. Horan, A. Nassiri
    ANL, Argonne, Illinois
  The Advanced Photon Source (APS) at Argonne National Laboratory is exploring the possibility of using radio frequency deflection to generate x-ray radiation pulses on the order of 1 pico-second (Delta t - 70%) or less*. This scheme is based on a proposal by A. Zholents et al.** that relies on manipulating the transverse momenta of the electrons in a bunch by using an rf deflecting cavity to induce a longitudinally dependent vertical deflection of the beam. The beam will then travel through a number of undulators before arriving at a second set of deflecting cavities where the deflection is reversed such that the remainder of the storage ring is largely unperturbed***. Considerable effort has been expended on the design of a superconducting rf deflecting cavity operating in the S-Band at 2.8 GHz to address fundamental design issues including cavity geometry, deflecting voltage, rf power coupling, tuning, and damping of higher-order and lower-order modes. In this paper we present simulation results and analysis of an optimized superconducting rf deflecting cavity design for the APS storage ring.

*K. Harkay et al. Proceedings of 2005 PAC, Knoxville, TN, May 2005, p. 668. **A. Zholents et al. Nucl. Instrum. Methods, A425, 385 (1999). ***M. Borland and V. Sajaev. Proceedings of 2005 PAC, Knoxville, TN, May 2005, p. 3886.