• S. Matsuba
  Hiroshima University, Graduate School of Science, Higashi-Hiroshima
• Y. Honda, T. Miyajima
  KEK, Ibaraki

En­er­gy Re­cov­ery Linac (ERL) as syn­chrotron light source is planned to con­struct in KEK. Be­fore the con­struc­tion of full-set of ERL, com­pact ERL to study the ac­cel­er­a­tor tech­nolo­gies will be con­struct­ed. For the in­jec­tor, a high volt­age pho­toe­mis­sion gun with DC op­er­a­tion and mea­sure­ment sys­tems for the low emit­tance beam will be de­vel­oped. In order to ob­serve bunch length and lon­gi­tu­di­nal beam pro­file, we have de­signed a sin­gle-cell de­flect­ing cav­i­ty with 2.6 GHz dipole mode. We de­scribe the op­ti­miza­tion of the cav­i­ty, me­chan­i­cal de­sign and the mea­sure­ments re­sults with sim­u­la­tion.

• Y.I. Kim, A. Heo, E.-S. Kim
  Kyungpook National University, Daegu
• S.T. Boogert
  Royal Holloway, University of London, Surrey
• Y. Honda, T. Tauchi, N. Terunuma
  KEK, Ibaraki
• J. May, D.J. McCormick, T.J. Smith
  SLAC, Menlo Park, California

Nanome­ter res­o­lu­tion Beam Po­si­tion Mon­i­tors have been de­vel­oped to mea­sure and con­trol beam po­si­tion sta­bil­i­ty at the in­ter­ac­tion point re­gion of ATF2. The po­si­tion of the beam fo­cused has to be mea­sured with­in a few nanome­ter res­o­lu­tion at the in­ter­ac­tion point. In order to achieve this per­for­mance, elec­tron­ics for this BPM was de­vel­oped. Every com­po­nent of the elec­tron­ics have been sim­u­lat­ed and checked by local test and using beam sig­nal. We will ex­plain each com­po­nent and de­fine their work­ing range. Then, we will show the per­for­mance of the elec­tron­ics mea­sured with beam sig­nal.

• S.T. Boogert, G.E. Boorman, C. Swinson
  JAI, Oxford
• R. Ainsworth, S. Molloy
  Royal Holloway, University of London, Surrey
• A.S. Aryshev, Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• J.C. Frisch, J. May, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White, M. Woodley
  SLAC, Menlo Park, California
• A. Heo, E.-S. Kim, H.-S. Kim, Y.I. Kim
  Kyungpook National University, Daegu
• A. Lyapin
  UCL, London
• H.K. Park
  KNU, Deagu
• M.C. Ross
  Fermilab, Batavia
• S. Shin
  PLS, Pohang

The Ac­cel­er­a­tor Test Fa­cil­i­ty 2 (ATF2) in KEK, Japan, is a pro­to­type scaled demon­stra­tor sys­tem for the final focus re­quired for a lep­ton lin­ear col­lid­er. The ATF2 beam-line is in­stru­ment­ed with a total of 38 C and S band res­o­nant cav­i­ty beam po­si­tion mon­i­tors (BPM) with as­so­ci­at­ed mixer elec­tron­ics and dig­i­tiz­ers. The cur­rent sta­tus of the BPM sys­tem is de­scribed, with a focus on op­er­a­tional tech­niques and per­for­mance.

• M.D. Hildreth
  University of Notre Dame, Notre Dame
• A.S. Aryshev
  Royal Holloway, University of London, Surrey
• S.T. Boogert
  JAI, Egham, Surrey
• Y. Honda, T. Tauchi, N. Terunuma
  KEK, Ibaraki
• G.R. White
  SLAC, Menlo Park, California

The demon­stra­tion of the sta­bil­i­ty of the po­si­tion of the fo­cused beam is a pri­ma­ry goal of the ATF2 pro­ject. We have in­stalled a laser in­ter­fer­om­e­ter sys­tem that will even­tu­al­ly cor­rect the mea­sure­ment of high-pre­ci­sion Beam Po­si­tion Mon­i­tors used in the ATF2 Final Focus Steer­ing Feed­back for me­chan­i­cal mo­tion or vi­bra­tions. Here, we de­scribe the in­stalled sys­tem and pre­sent pre­lim­i­nary data on the short- and long-term me­chan­i­cal sta­bil­i­ty of the BPM sys­tem.

• M.K. Fukuda, S. Araki, A.S. Aryshev, Y. Honda, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• A. Deshpande
  Sokendai, Ibaraki
• K. Sakaue, M. Washio
  RISE, Tokyo
• N. Sasao
  Okayama University, Okayama

We have de­vel­oped a com­pact X-ray source based on in­verse Comp­ton scat­ter­ing of an elec­tron beam and a laser pulse, which is stacked in an op­ti­cal su­per-cav­i­ty, at LUCX ac­cel­er­a­tor in KEK. The ac­cel­er­a­tor con­sists of a pho­to-cath­ode rf-gun and an S-band ac­cel­er­at­ing tube and pro­duces the mul­ti-bunch elec­tron beam with 100 bunch­es, 0.5nC bunch charge and 40MeV beam en­er­gy. It is planned to up­grade the ac­cel­er­a­tor and the su­per-cav­i­ty in order to in­crease the num­ber of X-rays. A new RF gun with high mode sep­a­ra­tion and high Q value and a new klystron for the gun will be in­stalled to pro­vide good com­pen­sa­tion with a high-in­ten­si­ty mul­ti-bunch elec­tron beam. A new op­ti­cal su­per-cav­i­ty con­sist­ing of 4 mir­rors is also being de­vel­oped to in­crease the stack­ing power in the cav­i­ty and to re­duce the laser size at the focal point. The first tar­gets are to pro­duce a mul­ti-bunch elec­tron beam with 1000 bunch­es, 0.5 nC bunch charge and 5 MeV beam en­er­gy in low en­er­gy mode and 100bunch­es, 2 nC and 40 MeV in high en­er­gy mode to gen­er­ate X-rays by in­verse Comp­ton scat­ter­ing. In this paper, the sta­tus and fu­ture plan of the ac­cel­er­a­tor will be re­port­ed.

• I. Ito, N. Nakamura
  ISSP/SRL, Chiba
• Y. Honda
  KEK, Ibaraki
• Y. Kobayashi, K. Torizuka, D. Yoshitomi
  AIST, Tsukuba

We are de­vel­op­ing an Yb fiber laser sys­tem that drives an ERL pho­to­cath­ode gun. An Yb fiber laser is ex­pect­ed to have both high sta­bil­i­ty and high out­put power re­quired for the drive laser of an ERL pho­to­cath­ode gun. First we start­ed to de­vel­op an Yb fiber laser os­cil­la­tor with a high rep­e­ti­tion rate up to 1.3 GHz that is the RF fre­quen­cy of a su­per­con­duct­ing ac­cel­er­at­ing cav­i­ty and then a 30W pream­pli­fi­er using an Yb doped pho­ton­ic crys­tal fiber. We re­port our re­cent progress in this de­vel­op­ment.

• T. Miyajima, K. Haga, K. Harada, T. Honda, Y. Honda, Y. Kobayashi, T.M. Mitsuhashi, S. Nagahashi, E. Nakamura, S. Nozawa, T. Ozaki, S. Sakanaka, K. Satoh, M. Shimada, T. Takahashi, R. Takai, M. Tobiyama, T. Uchiyama, A. Ueda, M. Yamamoto
  KEK, Ibaraki
• S. Matsuba
  Hiroshima University, Graduate School of Science, Higashi-Hiroshima
• T. Muto
  Tohoku University, School of Scinece, Sendai

Com­pact ERL (cERL) is a test ac­cel­er­a­tor to es­tab­lish ac­cel­er­a­tor tech­nolo­gies for GeV-class syn­chrotron light source based on ERL (En­er­gy Re­cov­ery Linac), and will be con­struct­ed in KEK. It con­sists of an in­jec­tor with photo cath­ode 500 kV DC gun, a merg­er sec­tion, super con­duct­ing RF cav­i­ties for ac­cel­er­a­tion and en­er­gy re­cov­ery, re­turn loops, and a beam dump. To op­er­ate and test the photo cath­ode gun be­fore in­stalling it in the cERL in­jec­tor, Gun Test Fa­cil­i­ty is con­struct­ing in KEK, AR south ex­per­i­men­tal hall. The Gun Test Fa­cil­i­ty has two photo cath­ode guns, 200 kV gun de­vel­oped by Nagoya Uni­ver­si­ty and new 500 kV gun which is being de­vel­oped, laser sys­tem to be emit­ted elec­trons from photo cath­ode sur­face, beam trans­port lines, and a beam di­ag­nos­tics sys­tem. The di­ag­nos­tics sys­tem con­sists of a dou­ble slit emit­tance mea­sure­ment sys­tem, beam po­si­tion mon­i­tors, trans­verse pro­file mon­i­tors, and a de­flect­ing cav­i­ty to mea­sure the bunch length and the lon­gi­tu­di­nal pro­file. In this pre­sen­ta­tion, the progress in the con­struc­tion of the Gun Test Fa­cil­i­ty and the beam dy­nam­ics sim­u­la­tion will be pre­sent­ed.

• R. Nagai, R. Hajima, N. Nishimori
  JAEA/ERL, Ibaraki
• Y. Honda, T. Miyajima, T. Muto, M. Yamamoto
  KEK, Ibaraki
• H. Iijima, M. Kuriki
  HU/AdSM, Higashi-Hiroshima
• M. Kuwahara, T. Nakanishi, S. Okumi
  Nagoya University, Nagoya

A 500-kV, 10-mA pho­to­cath­ode DC gun has been de­signed and is now under fab­ri­ca­tion by the col­lab­o­ra­tion ef­forts of JAEA, KEK, Hi­roshi­ma Univ. and Nagoya Univ. The Cock­croft-Wal­ton gen­er­a­tor and the ce­ram­ic in­su­la­tor are in­stalled up­right in the SF6 tank. We have adopt­ed a mul­ti­ple-stacked cylin­dri­cal ce­ram­ic in­su­la­tor, be­cause this type of ce­ram­ic in­su­la­tor has shown good sta­bil­i­ty and ro­bust­ness at the 200-kV Nagoya po­lar­ized gun and the 250-kV JAEA FEL gun. The vac­u­um cham­ber, the guard-rings and the sup­port-rod elec­trode are made of ti­ta­ni­um alloy with very low out-gassing and ro­bust­ness to high volt­age per­for­mances. The Cock­croft-Wal­ton gen­er­a­tor, the ce­ram­ic in­su­la­tor, the vac­u­um cham­ber and the guard-rings have been as­sem­bled and a high-volt­age test has been suc­cess­ful­ly done with up to 550kV. The high-volt­age test and up-to-date sta­tus of the gun de­vel­op­ment will be pre­sent­ed in de­tail.

• D. Okamoto
  Tohoku University, Graduate School of Science, Sendai
• Y. Honda, T. Tauchi
  KEK, Ibaraki
• T. Sanuki
  Tohoku University, School of Scinece, Sendai

We have stud­ied a beam orbit tilt mon­i­tor for sta­bi­liz­ing the beam orbit in ATF2. Once we can mea­sure a beam orbit tilt with high pre­ci­sion at one point, we can re­late this data with the beam po­si­tion pro­file at the focal point. A tilt mon­i­tor is com­posed of a sin­gle rect­an­gu­lar sen­sor cav­i­ty and a waveg­uide to ex­tract the sig­nal. In the sen­sor cav­i­ty, there is the most basic res­o­nant mode called monopole mode. This monopole mode is per­pen­dic­u­lar to the nom­i­nal beam axis, and ex­cit­ed by the beam tilt. We ex­tract this monopole mode. As the re­sult, the am­pli­tude of the ex­tract­ed sig­nal is pro­por­tion­al to the tilt angle. The tilt mon­i­tor is al­most in­dep­ne­dent with beam pos­tion, so we can get the tilt date in­de­pen­dent­ly. Ac­cord­ing to our sim­u­la­tion, the sen­si­tiv­i­ty is es­ti­mat­ed about 35n­rad in the ver­ti­cal di­rec­tion. The pro­to­type was com­plet­ed and in­stalled in the test area on the ATF2 beam­line. The first beam test will be per­formed in De­cem­ber 2009. We will re­port this re­sult and fu­ture up­date plan.

Slides

• T. Honda, T. Aoto, S. Asaoka, K. Ebihara, K. Furukawa, K. Haga, K. Harada, Y. Honda, T. Ieiri, N. Iida, M. Izawa, T. Kageyama, M. Kikuchi, Y. Kobayashi, K. Marutsuka, A. Mishina, T. Miyajima, H. Miyauchi, S. Nagahashi, T.T. Nakamura, T. Nogami, T. Obina, K. Oide, M. Ono, T. Ozaki, C.O. Pak, H. Sakai, H. Sakai, Y. Sakamoto, S. Sakanaka, H. Sasaki, Y. Sato, K. Satoh, M. Shimada, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, S. Takasaki, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto, Ma. Yoshida, S.I. Yoshimoto
  KEK, Ibaraki

KEK man­ages two syn­chrotron ra­di­a­tion sources, Pho­ton Fac­to­ry stor­age ring (PF-ring) of 2.5 GeV and Pho­ton Fac­to­ry ad­vanced ring (PF-AR) of 6.5 GeV. These rings share an in­jec­tor linac with the two main rings of KEK B-fac­to­ry, 8-GeV HER and 3.5-GeV LER. Re­cent­ly, the linac has suc­ceed­ed in a pulse by pulse mul­ti-en­er­gy ac­cel­er­a­tion. A top-up op­er­a­tion of PF-ring has been re­al­ized as the si­mul­ta­ne­ous con­tin­u­ous in­jec­tion to the 3 rings, PF-ring, HER and LER. De­vel­op­ment of new in­jec­tion scheme using a pulsed sex­tupole mag­net con­tin­ues aim­ing at prac­ti­cal use in the top-up op­er­a­tion. A rapid-po­lar­iza­tion-switch­ing de­vice con­sist­ing of tan­dem two AP­PLE-II type un­du­la­tors has been de­vel­oped at PF-ring. The first un­du­la­tor was in­stalled in 2008, and the sec­ond one will be in­stalled in 2010 sum­mer. PF-AR, op­er­at­ed in a sin­gle-bunch mode at all times, has been suf­fered from sud­den life­time drop phe­nom­e­na at­tribut­ed to dust trap­ping for many years. Using the mov­able elec­trodes in­stalled for ex­per­i­ment, we con­firmed that the dis­charge cre­at­ed by the elec­trode was fol­lowed by the dust trap­ping, and suc­ceed­ed in a vi­su­al ob­ser­va­tion of lu­mi­nous dust streak­ing in front of CCD cam­eras.

• 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.

• M. Kuriki, H. Iijima
  HU/AdSM, Higashi-Hiroshima
• H. Hayano, Y. Honda, H. Sugiyama, J. Urakawa
  KEK, Ibaraki
• G. Isoyama, S. Kashiwagi, R. Kato
  ISIR, Osaka
• E. Katin, E. Khazanov, V. Lozhkarev, G. Luchinin, A. Poteomkin
  IAP/RAS, Nizhny Novgorod
• G. Shirkov, G.V. Trubnikov
  JINR, Dubna, Moscow Region

Aim of Su­per-con­duct­ing Test Fa­cil­i­ty (STF) at KEK is demon­strat­ing tech­nolo­gies for In­ter­na­tion­al Lin­ear Col­lid­er. In STF, one full RF unit will be de­vel­oped and beam ac­cel­er­a­tion test will be made. In su­per-con­duct­ing ac­cel­er­a­tor, pre­cise RF con­trol in phase and power is es­sen­tial be­cause the input RF power should be bal­anced to beam ac­cel­er­at­ing power. To demon­strate the sys­tem fea­si­bil­i­ty, the beam ac­cel­er­at­ing test is an im­por­tant step in R&D phase of STF and ILC. To pro­vide ILC for­mat beam for STF, we de­vel­op an elec­tron source based on pho­to-cath­ode L-band RF gun. To gen­er­ate ILC for­mat beam, we de­vel­oped a laser sys­tem based on Yb fiber os­cil­la­tor in 40.6 MHz. The pulse rep­e­ti­tion is de­creased by pick­ing puls­es in 2.7 MHz, which meets ILC bunch spac­ing, 364 ns. The pulse is then am­pli­fied by YLF laser up to 8 uJ per pulse in 1 mm. The light is con­vert­ed to 266 nm by SHG and FHG. Fi­nal­ly, 1.5 uJ per pulse is ob­tained and 3.2 nC bunch charge will be made. We re­port the basic per­for­mance of the laser sys­tem from the ac­cel­er­a­tor tech­nol­o­gy point of a view.