• J. Alabau-Gonzalvo, C. Blanch Gutierrez, J.V. Civera, A. Faus-Golfe, J.J. García-Garrigós
  IFIC, Valencia
• J. Cruz, D.J. McCormick, G.R. White
  SLAC, Menlo Park, California

In this paper we de­scribe the de­sign, in­stal­la­tion and first cal­i­bra­tion tests of a Multi Op­ti­cal Tran­si­tion Ra­di­a­tion (OTR) mon­i­tor sys­tem in the beam di­ag­nos­tic sec­tion of the Ex­trac­tion (EXT) line of ATF2, close to the multi wire scan­ner sys­tem. This sys­tem will be a valu­able tool for mea­sur­ing beam sizes and emit­tances from the ATF Damp­ing Ring (DR). With an op­ti­cal res­o­lu­tion of about 2 um an orig­i­nal OTR de­sign demon­strat­ed the abil­i­ty to mea­sure a 5.5um beam size in one beam pulse and to take many fast mea­sure­ments. This gives the OTR the abil­i­ty to mea­sure the beam emit­tance with high statis­tics, giv­ing a low error and a good un­der­stand­ing of emit­tance jit­ter. Fur­ther­more the near by wire scan­ners will be a defini­tive test of the OTR as a beam emit­tance di­ag­nos­tic de­vice. The mu­ti-OTR sys­tem de­sign pro­posed here is based on the ex­ist­ing OTR1X, lo­cat­ed after the sep­tums at the en­trance of the EXT line.

• 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.

• G.R. White, A. Seryi, M. Woodley
  SLAC, Menlo Park, California
• S. Bai
  IHEP Beijing, Beijing
• P. Bambade, Y. Renier
  LAL, Orsay
• B. Bolzon
  IN2P3-LAPP, Annecy-le-Vieux
• Y. Kamiya
  ICEPP, Tokyo
• S. Komamiya, M. Oroku, Y. Yamaguchi, T. Yamanaka
  University of Tokyo, Tokyo
• K. Kubo, S. Kuroda, T. Okugi, T. Tauchi
  KEK, Ibaraki
• E. Marin
  CERN, Geneva

The pri­ma­ry aim of the ATF2 re­search ac­cel­er­a­tor is to test a scaled ver­sion of the final focus op­tics planned for use in next-gen­er­a­tion lin­ear lep­ton col­lid­ers. ATF2 con­sists of a 1.3 GeV linac, damp­ing ring pro­vid­ing low-emit­tance elec­tron beams (<12pm in the ver­ti­cal plane), ex­trac­tion line and final focus op­tics. The de­sign de­tails of the final focus op­tics and im­ple­men­ta­tion at ATF2 are pre­sent­ed else­where* . The ATF2 ac­cel­er­a­tor is cur­rent­ly being com­mis­sioned, with a staged ap­proach to achiev­ing the de­sign IP spot size. It is ex­pect­ed that as we im­ple­ment more de­mand­ing op­tics and re­duce the ver­ti­cal beta func­tion at the IP, the tun­ing be­comes more dif­fi­cult and takes longer. We pre­sent here a de­scrip­tion of the im­ple­men­ta­tion of the over­all tun­ing al­go­rithm and de­scribe op­er­a­tional ex­pe­ri­ences and per­for­mances

* Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System. Glen R. White , S. Molloy, M. Woodley, (SLAC). EPAC08-MOPP039, SLAC-PUB-13303.

Slides

• 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.

• P. Chu, R.H. Iverson, P. Krejcik, D. Rogind, G.R. White, M. Woodley
  SLAC, Menlo Park, California

Linac En­er­gy Man­age­ment (LEM) is a con­trol sys­tem pro­gram which cal­cu­lates, and op­tion­al­ly im­ple­ments, mag­net set­point set­tings (BDESs) fol­low­ing a change in En­er­gy (such as a change in the num­ber, phase, and am­pli­tude of ac­tive klystrons). The change is made rel­a­tive to those mag­nets' ex­ist­ing BDES set­points by a fac­tor en­cod­ing the change in en­er­gy. LEM is nec­es­sary be­cause changes in the num­ber, phase, and am­pli­tude of the ac­tive klystrons (the so-called "Klystron com­ple­ment") change the beam's rigid­i­ty, and there­fore, to main­tain con­stant op­tics, one has to change fo­cus­ing gra­di­ents and bend fields. This paper de­scribes the basic pro­cess and some of the im­ple­men­ta­tion lessons learned for LEM at the LCLS.

• B. Bolzon, A. Jeremie
  IN2P3-LAPP, Annecy-le-Vieux
• S. Bai
  IHEP Beijing, Beijing
• P. Bambade
  KEK, Ibaraki
• G.R. White
  SLAC, Menlo Park, California

At the first stage of the ATF2 beam tun­ing, ver­ti­cal beam size is usu­al­ly big­ger than 3um at the IP. Beam waist mea­sure­ments using wire scan­ners and a laser wire are usu­al­ly per­formed to check the ini­tial match­ing of the beam through to the IP. These mea­sure­ments are de­scribed in this paper for the op­tics cur­rent­ly used (βx=4cm and βy=1mm). Soft­ware im­ple­ment­ed in the con­trol room to au­to­mate these mea­sure­ments with in­te­grat­ed anal­y­sis is also de­scribed. Mea­sure­ments showed that beta func­tions and emit­tances were with­in er­rors of mea­sure­ments when no re­match­ing and cou­pling cor­rec­tions were done. How­ev­er, it was ob­served that the waist in the hor­i­zon­tal (X) and ver­ti­cal (Y) plane was ab­nor­mal­ly shift­ed and sim­u­la­tions were per­formed to try to un­der­stand these shifts. They also showed that mul­ti­knobs are need­ed in the cur­rent op­tics to cor­rect si­mul­ta­ne­ous­ly αx, αy and the hor­i­zon­tal dis­per­sion (Dx). Such mul­ti­knobs were found and their lin­ear­i­ty and or­thog­o­nal­i­ty were suc­cess­ful­ly checked using MAD op­tics code. The soft­ware for these mul­ti­knobs was im­ple­ment­ed in the con­trol room and waist scan mea­sure­ments using the αy knob were suc­cess­ful­ly per­formed.

• C. Rimbault
  LAL, Orsay
• S. Kuroda, T. Tauchi, N. Terunuma
  KEK, Ibaraki
• G.R. White, M. Woodley
  SLAC, Menlo Park, California

The pur­pose of ATF2 is to de­liv­er a beam with sta­ble very small spot­sizes as re­quired for fu­ture lin­ear col­lid­ers such as ILC or CLIC. To achieve that, pre­cise con­trols of the aber­ra­tions such as dis­per­sion and cou­pling are nec­es­sary. The­o­ret­i­cal­ly, the com­plete re­con­struc­tion of the beam ma­trix is pos­si­ble from the mea­sure­ments of hor­i­zon­tal, ver­ti­cal and tilt­ed beam sizes, com­bin­ing skew quadrupole scans at sev­er­al wire-scan­ner po­si­tions. Such mea­sure­ments were per­formed in the ex­trac­tion line of ATF2 in May 2009. We pre­sent anal­y­sis re­sults at­tempt­ing to re­solve the 4X4 beam ma­trix and dis­cuss the ex­per­i­men­tal lim­i­ta­tions of 4D emit­tance mea­sure­ments with wire scan­ners.

• B. Parker, M. Anerella, J. Escallier, P. He, A.K. Jain, A. Marone, P. Wanderer, K.-C. Wu
  BNL, Upton, Long Island, New York
• P. Bambade
  LAL, Orsay
• B. Bolzon, A. Jeremie
  IN2P3-LAPP, Annecy-le-Vieux
• P.A. Coe, D. Urner
  OXFORDphysics, Oxford, Oxon
• C. Hauviller, E. Marin, R. Tomás, F. Zimmermann
  CERN, Geneva
• N. Kimura, K. Kubo, T. Kume, S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, T. Tomaru, K. Tsuchiya, J. Urakawa, A. Yamamoto
  KEK, Ibaraki
• A. Seryi, C.M. Spencer, G.R. White
  SLAC, Menlo Park, California

The KEK ATF2 fa­cil­i­ty, with a well in­stru­ment­ed beam line and Final Focus (FF), is a prov­ing ground for lin­ear col­lid­er (LC) tech­nol­o­gy to demon­strate the ex­treme beam de­mag­ni­fi­ca­tion and spot sta­bil­i­ty need­ed for a LC FF*. ATF2 uses water cooled mag­nets but the base­line ILC calls for a su­per­con­duct­ing FF**. Thus we plan to re­place some ATF2 FF mag­nets with su­per­con­duct­ing ones made via di­rect wind con­struc­tion as planned for the ILC. With no cryo­genic sup­ply at ATF2, we look to cool mag­nets and cur­rent leads with a few cry­ocool­ers. ATF2 FF coil wind­ing is un­der­way at BNL and pro­duc­tion warm mag­net­ic mea­sure­ments in­di­cate good field qual­i­ty. Hav­ing FF mag­nets with larg­er aper­ture and bet­ter field qual­i­ty than pre­sent FF might allow re­duc­ing the beta func­tion at the FF for study of fo­cus­ing regimes rel­e­vant to CLIC. Our ATF2 mag­net cryo­stat will have laser view ports for cold mass move­ment mea­sure­ment and FF sup­port and sta­bi­liza­tion re­quire­ments under study. We plan to make sta­bil­i­ty mea­sure­ments at BNL and KEK to re­late ATF2 FF mag­net per­for­mance to that of a full length ILC R&D pro­to­type at BNL. We want to be able to pre­dict LC FF per­for­mance with con­fi­dence.

* ATF2 proposal, volumes 1 and 2 at http://lcdev.kek.jp/ILC-AsiaWG/WG4notes/atf2/proposal/index.html
** International Linear Collider Reference Design Report, ILC-REPORT-2007-001, August 2007.

• E. Marin, R. Tomás
  CERN, Geneva
• P. Bambade
  LAL, Orsay
• S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• B. Parker
  BNL, Upton, Long Island, New York
• A. Seryi, G.R. White, M. Woodley
  SLAC, Menlo Park, California

The cur­rent ATF2 Ul­tra-Low beta pro­pos­al was de­signed to achieve 20nm ver­ti­cal IP beam size with­out con­sid­er­ing the mul­ti­po­lar com­po­nents of the FD mag­nets. In this paper we de­scribe dif­fer­ent sce­nar­ios that avoid the detri­men­tal ef­fect of these mul­ti­po­lar er­rors in the FD. The sim­plest ap­proach con­sists in mod­i­fy­ing the op­tics but other so­lu­tions are stud­ied as the in­tro­duc­tion of new high­er order mag­nets or the re­place­ment of the FD with SC tech­nol­o­gy. The prac­ti­cal as­pects of such an up­grade are the tun­ing per­for­mance and the com­pat­i­bil­i­ty with ex­ist­ing de­vices and in­stru­men­ta­tion. These are fully ad­dressed in the paper.