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Higashi, Y.

Paper Title Page
MOPCH190 Cryomodule Development for Superconducting RF Test Facility (STF) at KEK 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.  
MOPLS084 Experimental Comparison at KEK of High Gradient Performance of Different Single Cell Superconducting Cavity Designs 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.  
MOPLS087 Series Test of High-gradient Single-cell Superconducting Cavity for the Establishment of KEK Recipe 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.  
WEPLS060 CLIC Polarized Positron Source Based on Laser Compton Scattering 2520
 
  • F. Zimmermann, H.-H. Braun, M. Korostelev, L. Rinolfi, D. Schulte
    CERN, Geneva
  • S. Araki, Y. Higashi, Y. Honda, Y. Kurihara, M. Kuriki, T. Okugi, T. Omori, T. Taniguchi, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • X. Artru, R. Chehab, M. Chevallier
    IN2P3 IPNL, Villeurbanne
  • E.V. Bulyak, P. Gladkikh
    NSC/KIPT, Kharkov
  • M.K. Fukuda, K. Hirano, M. Takano
    NIRS, Chiba-shi
  • J. Gao
    IHEP Beijing, Beijing
  • S. Guiducci, P. Raimondi
    INFN/LNF, Frascati (Roma)
  • T. Hirose, K. Sakaue, M. Washio
    RISE, Tokyo
  • K. Moenig
    DESY Zeuthen, Zeuthen
  • H.D. Sato
    HU/AdSM, Higashi-Hiroshima
  • V. Soskov
    LPI, Moscow
  • V.M. Strakhovenko
    BINP SB RAS, Novosibirsk
  • T. Takahashi
    Hiroshima University, Higashi-Hiroshima
  • A. Tsunemi
    SHI, Tokyo
  • V. Variola, Z.F. Zomer
    LAL, Orsay
 
  We describe the possible layout and parameters of a polarized positron source for CLIC, where the positrons are produced from polarized gamma rays created by Compton scattering of a 1.3-GeV electron beam off a YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring. We point out the differences with respect to a similar system proposed for the ILC.  
THPCH154 Development of Pulsed Laser Super-cavity for Compact High Flux X-ray Sources 3155
 
  • K. Sakaue, M. Washio
    RISE, Tokyo
  • S. Araki, Y. Higashi, Y. Honda, T. Taniguchi, J. Urakawa
    KEK, Ibaraki
  • M.K. Fukuda, M. Takano
    NIRS, Chiba-shi
  • H. Sakai
    ISSP/SRL, Chiba
  • N. Sasao
    Kyoto University, Kyoto
 
  Pulsed-laser super-cavity is being developed at KEK-ATF for the application of a compact high brightness x-ray source based on Laser Compton Scattering. We use a Fabry-Perot optical cavity with a pulsed laser. The cavity increases a laser effective power, and at the same time, stably makes a small laser spot in side the cavity. In addition, the pulsed-laser gives much higher peak power. Thus, this scheme will open up a new possibility for building a compact high-brightness x-ray source, when collided with an intense bunched electron beam. We are now planning to build such an x-ray source with a 50MeV multi-bunch linac and a 42cm Fabry-Perot cavity using pulse stacking technology. We actually finished construction of the 50MeV linac and will start its operation in the spring, 2006. Development of the pulsed-laser super-cavity and future plan of our compact x-ray source will be presented at the conference.