• F. Furugohri, H. Hioka, S. Someya
  SUT, Noda-shi, Chiba
• M. Yoshida
  KEK, Ibaraki

New ter­a­hertz(THz) gen­er­a­tor using the non-rel­a­tivis­tic elec­tron beam was de­vel­oped based on the beam op­tics and the RF de­flec­tor. The con­ven­tion­al THz gen­er­a­tors using the elec­tron beam are al­most based on the rel­a­tivis­tic beam to uti­lize the lorentz fac­tor as FELs or the strong mag­net to make high elec­tron den­si­ty like gy­rotrons or BWOs. Thus it caus­es that the total equip­ment be­comes large. New THz gen­er­a­tor uses the non-rel­a­tivis­tic elec­tron beam. And it con­sists of the beam op­tics which makes the sliced beam by using a anode slit to focus at sec­ond slit as the THz ra­di­a­tion plane. In this con­fig­u­ra­tion, the RF de­flec­tor works to move for the trans­verse di­rec­tion matched with the phase ve­loc­i­ty of the ra­di­at­ed elec­tro­mag­net­ic field. The mov­ing sliced beam sep­a­rates into a num­ber of bunch­es through the sec­ond slit and the bunch­es makes the THz co­her­ent ra­di­a­tion in zero time in­ter­val. In this new THz gen­er­a­tor, no strong mag­net is re­quired and the large di­am­e­ter beam can be uti­lized to gen­er­ate the high power THz elec­tro­mag­net­ic wave. In this paper,　the de­sign of new THz gen­er­a­tor and its ex­per­i­men­tal re­sults are re­port­ed.

• T. Imai, K. Tsukiyama
  Tokyo University of Science, IR FEL Research Center, Chiba
• K. Hisazumi, T. Morotomi
  MELCO SC, Tsukuba
• T. Shidara, M. Yoshida
  KEK, Ibaraki

IR-FEL re­search cen­ter of Tokyo Uni­ver­si­ty of Sci­ence (FEL-TUS) is a fa­cil­i­ty for aim­ing at the de­vel­op­ment of high per­for­mance FEL de­vice and pro­mo­tion of pho­to-sci­ence using it. The main part of FEL-TUS is a mid-in­frared FEL (MIR FEL) which con­sists of an S-band linac and an un­du­la­tor com­bined with an op­ti­cal res­o­nance cav­i­ty. MIR-FEL pro­vides con­tin­u­ous­ly tun­able ra­di­a­tion in the range of 5-14 mi­cron and a va­ri­ety of ex­per­i­ments are by the use of this pho­ton en­er­gy cor­re­spond­ing to the var­i­ous vi­bra­tional modes of molecules are now un­der­way. We also de­vel­op far-in­frared FEL (FIR FEL) in­stalled an RF-gun with Disk-and-Wash­er ac­cel­er­at­ing cav­i­ty for high qual­i­ty elec­tron beam. The cur­rent sta­tus of FEL-TUS will be pre­sent­ed.

• S. Sakanaka, M. Akemoto, T. Aoto, D.A. Arakawa, S. Asaoka, A. Enomoto, S. Fukuda, K. Furukawa, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, M. Isawa, E. Kako, T. Kasuga, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, T. Matsumoto, H. Matsushita, S. Michizono, T.M. Mitsuhashi, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, E. Nakamura, K. Nakanishi, K. Nakao, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, S. Ohsawa, T. Ozaki, C.O. Pak, H. Sakai, H. Sasaki, Y. Sato, K. Satoh, M. Satoh, T. Shidara, M. Shimada, T. Shioya, T. Shishido, T. Suwada, M. Tadano, T. Takahashi, R. Takai, T. Takenaka, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, S. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
  KEK, Ibaraki
• M. Adachi, M. Katoh, H. Zen
  UVSOR, Okazaki
• R. Hajima, R. Nagai, N. Nishimori, M. Sawamura
  JAEA/ERL, Ibaraki
• H. Hanaki
  JASRI/SPring-8, Hyogo-ken
• H. Iijima, M. Kuriki
  HU/AdSM, Higashi-Hiroshima
• I. Ito, H. Kudoh, N. Nakamura, S. Shibuya, K. Shinoe, H. Takaki
  ISSP/SRL, Chiba
• H. Kurisu
  Yamaguchi University, Ube-Shi
• M. Kuwahara, T. Nakanishi, S. Okumi
  Nagoya University, Nagoya
• S. Matsuba
  Hiroshima University, Graduate School of Science, Higashi-Hiroshima
• T. Muto
  Tohoku University, School of Scinece, Sendai
• K. Torizuka, D. Yoshitomi
  AIST, Tsukuba

Fu­ture syn­chrotron light source using a 5-GeV-class en­er­gy re­cov­ery linac (ERL) is under pro­pos­al by our Japanese col­lab­o­ra­tion team, and we are con­duct­ing ac­tive R&D ef­forts for that. We are de­vel­op­ing su­per-bril­liant DC pho­to­cath­ode guns, two types of cry­omod­ules for both in­jec­tor and main su­per­con­duct­ing linacs, 1.3 GHz high CW-pow­er rf sources, and other im­por­tant com­po­nents. We are also con­struct­ing a com­pact ERL for demon­strat­ing the re­cir­cu­la­tion of low-emit­tance, high-cur­rent beams using those key com­po­nents. We pre­sent our re­cent progress in this pro­ject.

• 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.

Slides

• M. Yoshida, S. Fukuda
  KEK, Ibaraki
• H. Asano, M. Kubosaki, Y. Moriguchi
  Mitsubishi Electric Corp., Communication Systems Center, Amagasaki City, Hyogo

The L-band in­duc­tive out­put tube (IOT) with­out trol­ly was de­vel­oped to op­er­ate under high­er ap­plied volt­age. The op­er­a­tion fre­quen­cy of con­ven­tion­al IOTs is tuned using its trol­ly. This mech­a­nism is based on the lower fre­quen­cy IOT. How­ev­er it caus­es less in­su­la­tion volt­age of the ce­ram­ics since the elec­tric in­su­la­tion oil is not avail­able for its trol­ly and the length of the in­su­la­tion ce­ram­ics is lim­it­ed be­cause it is a part of the res­o­nant cav­i­ty. In case of IOTs, it is im­por­tant to in­crease the ap­plied volt­age for high­er out­put power since the grid gap is very nar­row and its area can­not be in­creased to keep the gain. Thus we de­vel­oped an IOT which has a longer in­su­lat­ing ce­ram­ic and the input cav­i­ty is filled with vac­u­um to use the elec­tric in­su­la­tion oil. Fur­ther the di­elec­tric waveg­uide can solve to feed the input mi­crowave to the cath­ode grid with­out trol­ly. These new fea­tures of the IOT is very ef­fec­tive for the fixed fre­quen­cy ap­pli­ca­tion such as the ac­cel­er­a­tor, for ex­am­ple the en­er­gy re­cov­ery linac. The de­sign and the ex­per­i­men­tal re­sults will be pre­sent­ed in this re­port.

• 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

• 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.

• S. Fukuda, M. Akemoto, D.A. Arakawa, H. Honma, H. Katagiri, S. Matsumoto, T. Matsumoto, S. Michizono, T. Miura, H. Nakajima, K. Nakao, S. Sakanaka, T. Shidara, T. Takahashi, Y. Yano, M. Yoshida
  KEK, Ibaraki

ERL (En­er­gy Re­cov­ery Linac) of 5GeV en­er­gy is a fu­ture plan in KEK and in order to study the tech­ni­cal fea­si­bil­i­ty, con­struc­tion of a com­pact ERL ma­chine (cERL) is con­sid­ered. Beam en­er­gy and cur­rent of cERL are 245MeV and 100mA, re­spec­tive­ly. As 1.3 GHz fre­quen­cy and super con­duct­ing cav­i­ty are cho­sen for the RF sys­tem, sim­i­lar tech­nol­o­gy with KEK STF is em­ployed. From 2008, KEK start­ed the prepa­ra­tion of cERL and one RF unit of in­jec­tor linac is in­tro­duced in this fis­cal 2009. A new cw klystron of 300kW out put power, 150kW Y-type cir­cu­la­tor and high power water load were de­vel­oped in FY2009. DC power sup­ply was under man­u­fac­tur­ing. Pre­lim­i­nary test of HLRF and the high power cou­plers are sched­uled in the Pho­ton Fac­to­ry site by mak­ing use of the old DC power sup­ply. For main ac­cel­er­a­tor, we also in­tro­duced a 30kW IOT and a 35kW klystron and a DC power sup­ply. At the same time, cERL is de­ter­mined to be con­struct­ed in the East Counter Hall in KEK and the de­sign lay­out is pre­ced­ed. In this paper, the re­cent RF source de­vel­op­ment of cERL is de­scribed. Lay­out of the east counter hall, where cERL is con­struct­ed, is pro­gressed and shown in this re­port.

• 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.