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Masuzawa, M.

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.  
MOPLS031 Beam Orbit Control System for the KEKB Crab Cavities 613
 
  • M. Masuzawa, Y. Funakoshi, T.T. Nakamura, J.-I. Odagiri
    KEK, Ibaraki
 
  KEKB is an electron-positron collider with an 8 GeV electron ring (HER) and a 3.5 GeV positron ring (LER). The two beams currently collide at one interaction point with a finite horizontal crossing angle of 11 mrad. The design luminosity of 10 /nb/sec was first reached in May 2003 and the peak luminosity exceeded 16 /nb/sec in December 2005. Simulations predict a luminosity boost if a crab crossing scheme is introduced. The installation of two superconducting crab cavities, one in each ring, is scheduled in March 2006 in order to implement the crab crossing scheme. For stable operation, the horizontal beam position in the crab cavity must be carefully controlled. This is needed to avoid loss of control of the crabbing mode field due to beam loading. A beam position feedback system at the crab cavity has been prepared and tested. Its performance will be discussed in this report.  
WEPLS089 Feasibility Study of a Permanent Magnet Made from High-Tc Bulk Superconductor 2580
 
  • M. Masuzawa, K. Egawa, K. Tsuchiya
    KEK, Ibaraki
 
  A field trapping experiment using a magnetic field up to ~1.5 T was performed using high-Tc bulk superconductors. Applications of bulk high-Tc superconductors have been investigated in various fields. High-Tc superconductors are attractive since they can trap higher magnetic fields than conventional permanent magnets. The trapping experiment was done with a field of above 1 T, which can be easily produced by conventional magnets. However, achieving the desired field distribution and understanding the characteristics of the trapped field and its decay process would open up the possibility of high-Tc bulk superconductor applications in the design of magnets for particle accelerators The distribution of the trapped field and its decay process was monitored by an array of Hall sensors for different shapes of the bulk superconductors. The observations are reported on in this paper.