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Yokoyama, K.

Paper Title Page
WEOAMH02 Recent Progress of KEKB 2372
 
  • Y. Funakoshi, T. Abe, K. Akai, Y. Cai, K. Ebihara, K. Egawa, A. Enomoto, J.W. Flanagan, H. Fukuma, K. Furukawa, T. Furuya, J. Haba, T. Ieiri, N. Iida, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, S. Kamada, T. Kamitani, S. Kato, M. Kikuchi, E. Kikutani, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, A. Morita, T.T. Nakamura, K. Nakanishi, M. Nishiwaki, Y. Ogawa, K. Ohmi, Y. Ohnishi, N. Ohuchi, K. Oide, T. Oki, M. Ono, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, T. Sugimura, Y. Susaki, T. Suwada, M. Tawada, M. Tejima, M. Tobiyama, N. Tokuda, S. Uehara, S. Uno, Y. Yamamoto, Y. Yano, K. Yokoyama, M. Yoshida, S.I. Yoshimoto, D.M. Zhou, Z.G. Zong
    KEK, Ibaraki
 
 

KEKB is an e-/e+ col­lid­er for the study of B physics and is also used for ma­chine stud­ies for fu­ture ma­chines. The peak lu­mi­nos­i­ty of KEKB, which is the world-high­est value, has been still in­creas­ing. This re­port sum­ma­rizes re­cent progress at KEKB.

 

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Slides

 
THPEA012 Various Observables of TW Accelerator Structures Operating 100MV/m or Higher at X-band Facility, Nextef of KEK 3699
 
  • T. Higo, T. Abe, M. Akemoto, S. Fukuda, N. Higashi, Y. Higashi, N.K. Kudo, S. Matsumoto, T. Shidara, T. Takatomi, K. Ueno, Y. Watanabe, K. Yokoyama, M. Yoshida
    KEK, Ibaraki
 
 

Under the CERN-SLAC-KEK col­lab­o­ra­tion, we have been de­vel­op­ing the high gra­di­ent TW ac­cel­er­a­tor struc­tures. One of the main fo­cus­es is the fea­si­bil­i­ty study of CLIC ac­cel­er­a­tor struc­ture at X-band. A high power fa­cil­i­ty, Nex­tef*, was es­tab­lished at KEK in 2007. A few struc­tures have been test­ed, in­clud­ing an un-damped disk-load­ed struc­ture suc­cess­ful­ly test­ed be­yond 100 MV/m, a heav­i­ly damped struc­ture to be test­ed from late 2009 and a struc­ture made in a quad­rant con­fig­u­ra­tion. These struc­tures fol­low the same ac­cel­er­at­ing-mode RF pa­ram­e­ter pro­file, called CLIC-C**, but show dif­fer­ent fea­tures at high gra­di­ent op­er­a­tion. Var­i­ous ob­serv­ables, such as dark cur­rent, vac­u­um ac­tiv­i­ties, light emis­sion, break­down rate, and so on, are mea­sured. We dis­cuss the high gra­di­ent phe­nom­e­na re­lat­ed to these ob­serv­ables and the pos­si­ble im­prove­ment for sta­ble op­er­a­tion at a high­er gra­di­ent.


* T. Higo et al., THP038, LINAC06,2006.
**A. Grudiev, http://indico.cern.ch/conferenceDisplay.py?confId=30911

 
THPEA013 Advances in X-band TW Accelerator Structures Operating in the 100 MV/m Regime 3702
 
  • T. Higo, Y. Higashi, S. Matsumoto, K. Yokoyama
    KEK, Ibaraki
  • C. Adolphsen, V.A. Dolgashev, A. Jensen, L. Laurent, S.G. Tantawi, F. Wang, J.W. Wang
    SLAC, Menlo Park, California
  • S. Döbert, A. Grudiev, G. Riddone, W. Wuensch, R. Zennaro
    CERN, Geneva
 
 

A CERN-SLAC-KEK col­lab­o­ra­tion on high gra­di­ent X-band ac­cel­er­a­tor struc­ture de­vel­op­ment for CLIC has been on­go­ing for three years. The major out­come has been the demon­stra­tion of sta­ble 100 MV/m gra­di­ent op­er­a­tion of a num­ber of CLIC pro­to­type struc­tures. These struc­tures were fab­ri­cat­ed ba­si­cal­ly using the tech­nol­o­gy de­vel­oped from 1994 to 2004 for the GLC/NLC lin­ear col­lid­er ini­tia­tive. One goal has been to re­fine the es­sen­tial pa­ram­e­ters and fab­ri­ca­tion pro­ce­dures need­ed to re­al­ize such high gra­di­ent rou­tine­ly. An­oth­er goal has been to de­vel­op struc­tures with stronger dipole mode damp­ing than those for GLC/NLC. The lat­ter re­quires that sur­face tem­per­a­ture rise dur­ing the puls­es be high­er, which may in­crease the break­down rate. Struc­tures with heavy damp­ing will be test­ed in late 2009/early 2010, and this paper will pre­sent these re­sults to­geth­er with some of the ear­li­er re­sults from non-damped struc­tures and struc­tures built with a quad­rant ge­om­e­try.

 
THPEA015 L-band Accelerator System in Injector Linac for SuperKEKB 3708
 
  • S. Matsumoto, M. Akemoto, T. Higo, H. Honma, K. Kakihara, T. Kamitani, H. Nakajima, K. Nakao, Y. Ogawa, Y. Yano, K. Yokoyama, M. Yoshida
    KEK, Ibaraki
 
 

In order to im­prove the cap­ture ef­fi­cien­cy of the positron pro­duced at the tar­get in pre­sent KEKB In­jec­tor linac, a new pro­ject has just start­ed to uti­lize L-band (1298MHz) RF. The pre­sent S-band (2856MHz) cap­ture cav­i­ties and suc­ces­sive three RF units are to be re­placed by those of L-band. The spec­i­fi­ca­tions of the L-Band sys­tem should ful­fill the de­mands of a positron damp­ing ring down­stream which is also to be under study for super KEKB pro­ject. Be­sides the whole de­sign work of the sys­tem, our pre­sent on­go­ing work is rather con­cen­trat­ed on es­tab­lish­ing L-Band RF source and ac­cel­er­at­ing struc­tures.

 
THPD007 The Linac Upgrade Plan for SuperKEKB 4290
 
  • T. Sugimura, M. Akemoto, D.A. Arakawa, A. Enomoto, S. Fukuda, K. Furukawa, T. Higo, H. Honma, M. Ikeda, E. Kadokura, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, H. Nakajima, K. Nakao, Y. Ogawa, S. Ohsawa, M. Satoh, T. Shidara, A. Shirakawa, T. Suwada, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida
    KEK, Ibaraki
 
 

The next gen­er­a­tion B-fac­to­ry 'Su­perKEKB' pro­ject whose tar­get lu­mi­nos­i­ty is 8 ×1035 cm-2s-1 is under con­sid­er­a­tion. A 'nano-beam scheme' is in­tro­duced to the Su­perKEKB. In the scheme, an elec­tron beam (En­er­gy = 7 GeV, Charge = 3-4 nC/bunch, Ver­ti­cal emit­tance =2.8 x 10-5 m) and a positron beam (En­er­gy = 4 GeV, Charge = 4 nC/bunch, Ver­ti­cal emit­tance = 1.6 x 10-5 m), are re­quired at the end of in­jec­tor linac. They are quite chal­leng­ing tar­gets for the pre­sent linac. In order to meet the re­quire­ments, we will in­tro­duce some new com­po­nents to the linac. They are a pho­to-cath­ode RF gun for an elec­tron beam, a positron cap­ture sec­tion using new L-band cav­i­ties, a newly de­signed positron-gen­er­a­tion tar­get sys­tem and a damp­ing ring for a positron beam. This pre­sen­ta­tion shows a strat­e­gy of our in­jec­tor up­grade.