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Saito, K.

Paper Title Page
MOZAKI01 Compensation of the Crossing Angle with Crab Cavities at KEKB 27
 
  • K. Oide
  • T. Abe, K. Akai, M. Akemoto, A. Akiyama, A. Arinaga, K. Ebihara, K. Egawa, A. Enomoto, J. W. Flanagan, S. Fukuda, H. Fukuma, Y. Funakoshi, K. Furukawa, T. Furuya, K. Hara, T. Higo, S. Hiramatsu, H. Hisamatsu, H. Honma, K. Hosoyama, T. Ieiri, N. Iida, H. Ikeda, M. Ikeda, S. Isagawa, H. Ishii, A. Kabe, E. Kadokura, T. Kageyama, K. Kakihara, E. Kako, S. Kamada, T. Kamitani, K.-I. Kanazawa, H. Katagiri, S. Kato, T. Kawamoto, S. Kazakov, M. Kikuchi, E. Kikutani, K. Kitagawa, H. Koiso, Y. Kojima, K. Komada, T. Kubo, K. Kudo, N. K. Kudo, K. Marutsuka, M. Masuzawa, S. Matsumoto, T. Matsumoto, S. Michizono, K. Mikawa, T. Mimashi, S. Mitsunobu, K. Mori, A. Morita, Y. Morita, H. Nakai, H. Nakajima, T. T. Nakamura, H. Nakanishi, K. Nakao, S. Ninomiya, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, Y. Ohsawa, N. Ohuchi, M. Ono, T. Ozaki, K. Saito, H. Sakai, Y. Sakamoto, M. Sato, M. Satoh, K. Shibata, T. Shidara, M. Shirai, A. Shirakawa, T. Sueno, M. Suetake, Y. Suetsugu, R. Sugahara, T. Sugimura, T. Suwada, O. Tajima, S. Takano, S. Takasaki, T. Takenaka, Y. Takeuchi, M. Tawada, M. Tejima, M. Tobiyama, N. Tokuda, S. Uehara, S. Uno, Y. Yamamoto, Y. Yano, K. Yokoyama, Ma. Yoshida, M. Yoshida, S. I. Yoshimoto, K. Yoshino
    KEK, Ibaraki
  • E. Perevedentsev, D. N. Shatilov
    BINP SB RAS, Novosibirsk
  
  The crab cavities are presently being installed in the KEKB rings to compensate the crossing angle at collision and thus increase luminosity. This will be the first experience with such cavities in colliders. Results on the beam operation of the new cavities, both for single and colliding beams, will be presented including the luminosity performance and limitations.

Work presented on behalf of the KEKB Accelerator Group.

 
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WEPMN021 High Pressure Rinsing System Comparison 2092
 
  • D. Sertore
  • G. Ciovati, T. M. Rothgeb
    Jefferson Lab, Newport News, Virginia
  • M. Fusetti, P. Michelato, C. Pagani
    INFN/LASA, Segrate (MI)
  • T. Higo, J. H. Hong, K. Saito
    KEK, Ibaraki
  
  High pressure rinsing (HPR) is a key process for the surface preparation of high field superconducting cavities. A portable apparatus for the water jet characterization, based on the transferred momentum between the water jet and a load cell, has been used in different laboratories. This apparatus allows to collected quantitative parameters that characterize the HPR water jet. In this paper, we present a quantitative comparison of the different water jet produced by various nozzles routinely used in different laboratories for the HPR process  
WEPMN026 Test Operation of Ball-Screw-Type Tuner for Low-Loss High-Gradient Superconducting Cavity in a Cryomodule 2104
 
  • T. Higo
  • F. Furuta, Y. Higashi, T. Saeki, K. Saito, M. Satoh, H. Yamaoka
    KEK, Ibaraki
  
  We are constructing a Superconducting RF Test Facility (STF) at KEK as an R&D for ILC accelerator. In STF, four Low-Loss (LL) type 9-cell cavities will be installed into a cryomodule. We are developing ball-screw-type tuner for these cavities aiming at the accelerating gradient of 45 MV/m. At the end of 2006, we installed one LL 9-cell cavity dressed with the ball-screw tuner into the cryomodule. It will be operated without beam in 2007. This paper describes the results of the first operation of the ball-screw tuner for LL 9-cell cavity in the cryomodule of STF.  
WEPMN037 Manufacture and Assembly of the 6 Meter-Long Cryomodules for Superconducting RF Test Facility (STF) at KEK 2122
 
  • T. Semba
  • Y. Itou, S. Kajiura, T. Masumoto, T. Tagawa
    Hitachi Ltd., Ibaraki-ken
  • S. Noguchi, N. Ohuchi, K. Saito, A. Terashima, K. Tsuchiya
    KEK, Ibaraki
  
  The Superconducting RF Test Facility (STF) has been developed at KEK as an R&D toward ILC (International Linear Collider). Hitachi carried out the fabrication of STF cryostat components and in si-tu assembly of cryomodules cooperated with KEK. Our objective is obtaining the manufacturing experience of long cryostats for superconducting cavities. STF cryomodules are designed on the basis of TESLA design. Those major components are : vacuum vessels, support posts, 80K radiation shields, 5K radiation shields, helium gas return pipe, cryogenic piping, cavity helium vessels, RF input couplers, various measurement equipments and sensors. Two units of 6-meter long cryostat are designed to contain maximum eight 9-cell cavities in total. At the first step of the cryomodules, two different types of cavities and some equipments have been carefully prepared and installed by KEK. This paper briefly presents the structural design of STF cryostat components, cryomodule assembly procedures with specially designed tooling, and a summary for the next step.  
WEPMN047 Electro-polished Cavities Using China Ningxia Large Grain Niobium Material 2143
 
  • Z. G. Zong
  • F. Furuta, H. Inoue, T. Saeki, K. Saito
    KEK, Ibaraki
  • J. Gao, M. Q. Ge, Q. J. Xu, J. Y. Zhai
    IHEP Beijing, Beijing
  
  For the International Linear Collider (ILC), superconducting RF cavity technology was chosen. The superconducting cavity is made of polycrystalline niobium material so far. However, the material cost is high and the cavity performance has a rather scatter now. Large grain niobium (LG) cavity is an excellent idea because it simplifies the production process and results in less expensive. JLAB and DESY are pushing the R&D in last two years. KEK also has started to investigate LG. Three cavities with Ichiro shape were made of Chinese large grain niobium (Ningxia). A series of vertical tests has been carried out on several different surfaces treatment procedures by electropolishing. One cavity has reached the high gradient of more than 43 MV/m repeatedly. Other two cavities are still under testing. In this paper, the features of LG on electropolishing will be described with Ningxia large grain niobium material.  
WEPMS042 Optimization of the Low-Loss SRF Cavity for the ILC 2439
 
  • Z. Li
  • L. Ge, K. Ko, L. Lee, C.-K. Ng, G. L. Schussman, L. Xiao
    SLAC, Menlo Park, California
  • T. Higo, Y. Morozumi, K. Saito
    KEK, Ibaraki
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • J. S. Sekutowicz
    DESY, Hamburg
  
  Funding: Work supported by DOE contract DE-AC02-76SF00515.

The Low-Loss shape cavity design has been proposed as a possible alternative to the baseline TESLA cavity design for the ILC. The advantages of this design over the TESLA cavity are its lower cryogenic loss, and higher achievable gradient due to lower surface fields. High gradient prototypes for such designs have been tested at KEK (ICHIRO) and JLab (LL). However, issues related to HOM damping and multipacting (MP) still need to be addressed. Preliminary numerical studies of the prototype cavities have shown unacceptable damping for some higher-order dipole modes if the typical TESLA HOM couplers are directly adapted to the design. The resulting wakefield will dilute the beam emittance thus reduces the machine luminosity. Furthermore, high gradient tests on a 9-cell prototype at KEK have experienced MP barriers although a single LL cell had achieved a high gradient. From simulations, MP activities are found to occur in the end-groups of the cavity. In this paper, we will present the optimization results of the end-groups for the Low-Loss shape for effective HOM damping and alleviation of multipacting. Comparisons of simulation results with measurements will also be presented.

 
THOAKI03 Revision of Accelerating and Damping Structures for KEK STF 45 MV/m Accelerator Modules 2575
 
  • Y. Morozumi
  • F. Furuta, T. Higo, T. Saeki, K. Saito
    KEK, Ibaraki
  
  KEK is constructing its superconducting RF test facility and installing 1.3 GHz superconducting accelerator structures. Learning from experience with our first 45MV/m 9-cell structures, we have revised accelerating structures as well as higher order mode dampers for improved performance. Problems found in the earlier structures are discussed and solutions are presented. New experimental results will be also reported.  
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TUPAN045 Beam Operation with Crab Cavities at KEKB 1487
 
  • H. Koiso
  • T. Abe, T. A. Agoh, K. Akai, M. Akemoto, A. Akiyama, A. Arinaga, K. Ebihara, K. Egawa, A. Enomoto, J. W. Flanagan, S. Fukuda, H. Fukuma, Y. Funakoshi, K. Furukawa, T. Furuya, K. Hara, T. Higo, S. Hiramatsu, H. Hisamatsu, H. Honma, T. Honma, K. Hosoyama, T. Ieiri, N. Iida, H. Ikeda, M. Ikeda, S. Inagaki, S. Isagawa, H. Ishii, A. Kabe, E. Kadokura, T. Kageyama, K. Kakihara, E. Kako, S. Kamada, T. Kamitani, K.-I. Kanazawa, H. Katagiri, S. Kato, T. Kawamoto, S. Kazakov, M. Kikuchi, E. Kikutani, K. Kitagawa, Y. Kojima, I. Komada, T. Kubo, K. Kudo, N. K. Kudo, K. Marutsuka, M. Masuzawa, S. Matsumoto, T. Matsumoto, S. Michizono, K. Mikawa, T. Mimashi, S. Mitsunobu, K. Mori, A. Morita, Y. Morita, H. Nakai, H. Nakajima, T. T. Nakamura, H. Nakanishi, K. Nakao, S. Ninomiya, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, Y. Ohsawa, N. Ohuchi, K. Oide, M. Ono, T. Ozaki, K. Saito, H. Sakai, Y. Sakamoto, M. Sato, M. Satoh, K. Shibata, T. Shidara, M. Shirai, A. Shirakawa, T. Sueno, M. Suetake, Y. Suetsugu, R. Sugahara, T. Sugimura, T. Suwada, O. Tajima, S. Takano, S. Takasaki, T. Takenaka, Y. Takeuchi, M. Tawada, M. Tejima, M. Tobiyama, N. Tokuda, S. Uehara, S. Uno, Y. Yamamoto, Y. Yano, K. Yokoyama, Ma. Yoshida, M. Yoshida, S. I. Yoshimoto, K. Yoshino
    KEK, Ibaraki
  • E. Perevedentsev
    BINP SB RAS, Novosibirsk
  
  Beam operation with crab cavities is planned in early 2007 at KEKB. The crab crossing scheme is expected to increase the vertical beam-beam tune-shift parameter significantly. One crab cavity will be installed in each ring where conditions for beam optics are matched to compensate the beam crossing angle of 22 mrad. Operation results on collision tuning with the crab cavities will be presented.

For the KEKB Accelerator Group.